WorldWideScience

Sample records for dioxide climate forcing

  1. Carbon dioxide and climate

    International Nuclear Information System (INIS)

    1991-10-01

    Global climate change is a serious environmental concern, and the US has developed ''An Action Agenda'' to deal with it. At the heart of the US effort is the US Global Change Research Program (USGCRP), which has been developed by the Committee on Earth and Environmental Sciences (CEES) of the Federal Coordinating Council for Sciences, Engineering, and Technology (FCCSET). The USGCRP will provide the scientific basis for sound policy making on the climate-change issue. The DOE contribution to the USGCRP is the Carbon Dioxide Research Program, which now places particular emphasis on the rapid improvement of the capability to predict global and regional climate change. DOE's Carbon Dioxide Research Program has been addressing the carbon dioxide-climate change connection for more than twelve years and has provided a solid scientific foundation for the USGCRP. The expansion of the DOE effort reflects the increased attention that the Department has placed on the issue and is reflected in the National Energy Strategy (NES) that was released in 1991. This Program Summary describes projects funded by the Carbon Dioxide Research Program during FY 1991 and gives a brief overview of objectives, organization, and accomplishments. The Environmental Sciences Division of the Office of Health and Environmental Research, Office of Energy Research supports a Carbon Dioxide Research Program to determine the scientific linkage between the rise of greenhouse gases in the atmosphere, especially carbon dioxide, and climate and vegetation change. One facet is the Core CO 2 Program, a pioneering program that DOE established more than 10 years ago to understand and predict the ways that fossil-fuel burning could affect atmospheric CO 2 concentration, global climate, and the Earth's biosphere. Major research areas are: global carbon cycle; climate detection and models of climate change; vegetation research; resource analysis; and, information and integration

  2. Carbon dioxide and climate

    Energy Technology Data Exchange (ETDEWEB)

    1990-10-01

    Scientific and public interest in greenhouse gases, climate warming, and global change virtually exploded in 1988. The Department's focused research on atmospheric CO{sub 2} contributed sound and timely scientific information to the many questions produced by the groundswell of interest and concern. Research projects summarized in this document provided the data base that made timely responses possible, and the contributions from participating scientists are genuinely appreciated. In the past year, the core CO{sub 2} research has continued to improve the scientific knowledge needed to project future atmospheric CO{sub 2} concentrations, to estimate climate sensitivity, and to assess the responses of vegetation to rising concentrations of CO{sub 2} and to climate change. The Carbon Dioxide Research Program's goal is to develop sound scientific information for policy formulation and governmental action in response to changes of atmospheric CO{sub 2}. The Program Summary describes projects funded by the Carbon Dioxide Research Program during FY 1990 and gives a brief overview of objectives, organization, and accomplishments.

  3. Climate forcing by anthropogenic aerosols

    Energy Technology Data Exchange (ETDEWEB)

    Charlson, R J; Schwartz, S E; Hales, J M; Cess, R D; Coakley, Jr, J A; Hansen, J E; Hofmann, D J [University of Washington, Seattle, WA (USA). Inst. for Environmental Studies, Dept. of Atmospheric Sciences

    1992-01-24

    Although long considered to be of marginal importance to global climate change, tropospheric aerosol contributes substantially to radiative forcing, and anthropogenic sulfate aerosol in particular has imposed a major perturbation to this forcing. Both the direct scattering of short wavelength solar radiation and the modification of the shortwave reflective properties of clouds by sulfate aerosol particles increase planetary albedo, thereby exerting a cooling influence on the planet. Current climate forcing due to anthropogenic sulfate is estimated to be -1 to -2 watts per square metre, globally averaged. This perturbation is comparable in magnitude to current anthropogenic greenhouse gas forcing but opposite in sign. Thus, the aerosol forcing has likely offset global greenhouse warming to a substantial degree. However, differences in geographical and seasonal distributions of these forcings preclude any simple compensation. Aerosol effects must be taken into account in evaluating anthropogenic influences on past, current, and projected future climate and in formulating policy regarding controls on emission of greenhouse gases and sulfur dioxide. Resolution of such policy issues requires integrated research on the magnitude and geographical distribution of aerosol climate forcing and on the controlling chemical and physical processes. 73 refs., 4 figs., 2 tabs.

  4. Climate forcing by anthropogenic aerosols.

    Science.gov (United States)

    Charlson, R J; Schwartz, S E; Hales, J M; Cess, R D; Coakley, J A; Hansen, J E; Hofmann, D J

    1992-01-24

    Although long considered to be of marginal importance to global climate change, tropospheric aerosol contributes substantially to radiative forcing, and anthropogenic sulfate aerosol in particular has imposed a major perturbation to this forcing. Both the direct scattering of shortwavelength solar radiation and the modification of the shortwave reflective properties of clouds by sulfate aerosol particles increase planetary albedo, thereby exerting a cooling influence on the planet. Current climate forcing due to anthropogenic sulfate is estimated to be -1 to -2 watts per square meter, globally averaged. This perturbation is comparable in magnitude to current anthropogenic greenhouse gas forcing but opposite in sign. Thus, the aerosol forcing has likely offset global greenhouse warming to a substantial degree. However, differences in geographical and seasonal distributions of these forcings preclude any simple compensation. Aerosol effects must be taken into account in evaluating anthropogenic influences on past, current, and projected future climate and in formulating policy regarding controls on emission of greenhouse gases and sulfur dioxide. Resolution of such policy issues requires integrated research on the magnitude and geographical distribution of aerosol climate forcing and on the controlling chemical and physical processes.

  5. Carbon dioxide and future climate

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, J M

    1977-03-01

    The addition of carbon dioxide to the atmosphere due to burning fossil fuel is discussed. The release rate of carbon dioxide has been growing since at least 1950 at an average rate of 4.3% per year. If all known fossil fuel reserves in the world are consumed, a total of between 5 and 14 times the present amount of carbon dioxide in the atmosphere will be released. The oceans would then be unlikely to withdraw the proportion of perhaps 40% which they are believed to have withdrawn up to the present. The increase in the atmosphere would be in excess of 3 times or conceivably ten times the present amount. If the reserves are used up within a few hundred years, more than half the excess carbon dioxide would remain in the atmosphere after a thousand years. The ''greenhouse'' effect of carbon dioxide is explained. The simulation with numerical models of the effects of carbon dioxide on atmospheric radiation fluxes is discussed. An estimated increase in the average annual temperature of the earth of 2.4 to 2.9C is given for doubling the carbon dioxide content; also a 7% increase in global average precipitation. The effect of increasing carbon dioxide on global mean temperature is viewed in the perspective of the glacial-interglacial cycles. The warming effect of carbon dioxide may induce a ''super-interglacial'' on the present interglacial which is expected to decline toward a new ice age in the next several thousand years. Finally it is proposed that it may be necessary to phase out the use of fossil fuels before all the knowledge is acquired which would necessitate such an action.

  6. Climate Forcing Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Records of changes in solar irradiance, volcanic aerosols, atmospheric trace gases, and other properties thought to influence climate in the past. Parameter keywords...

  7. Climate hypersensitivity to solar forcing?

    Directory of Open Access Journals (Sweden)

    W. Soon

    2000-05-01

    Full Text Available We compare the equilibrium climate responses of a quasi-dynamical energy balance model to radiative forcing by equivalent changes in CO2, solar total irradiance (Stot and solar UV (SUV. The response is largest in the SUV case, in which the imposed UV radiative forcing is preferentially absorbed in the layer above 250 mb, in contrast to the weak response from global-columnar radiative loading by increases in CO2 or Stot. The hypersensitive response of the climate system to solar UV forcing is caused by strongly coupled feedback involving vertical static stability, tropical thick cirrus ice clouds and stratospheric ozone. This mechanism offers a plausible explanation of the apparent hypersensitivity of climate to solar forcing, as suggested by analyses of recent climatic records. The model hypersensitivity strongly depends on climate parameters, especially cloud radiative properties, but is effective for arguably realistic values of these parameters. The proposed solar forcing mechanism should be further confirmed using other models (e.g., general circulation models that may better capture radiative and dynamical couplings of the troposphere and stratosphere.Key words: Meteorology and atmospheric dynamics (climatology · general or miscellaneous · Solar physics · astrophysics · and astronomy (ultraviolet emissions

  8. Irreversible climate change due to carbon dioxide emissions

    Science.gov (United States)

    Solomon, Susan; Plattner, Gian-Kasper; Knutti, Reto; Friedlingstein, Pierre

    2009-01-01

    The severity of damaging human-induced climate change depends not only on the magnitude of the change but also on the potential for irreversibility. This paper shows that the climate change that takes place due to increases in carbon dioxide concentration is largely irreversible for 1,000 years after emissions stop. Following cessation of emissions, removal of atmospheric carbon dioxide decreases radiative forcing, but is largely compensated by slower loss of heat to the ocean, so that atmospheric temperatures do not drop significantly for at least 1,000 years. Among illustrative irreversible impacts that should be expected if atmospheric carbon dioxide concentrations increase from current levels near 385 parts per million by volume (ppmv) to a peak of 450–600 ppmv over the coming century are irreversible dry-season rainfall reductions in several regions comparable to those of the “dust bowl” era and inexorable sea level rise. Thermal expansion of the warming ocean provides a conservative lower limit to irreversible global average sea level rise of at least 0.4–1.0 m if 21st century CO2 concentrations exceed 600 ppmv and 0.6–1.9 m for peak CO2 concentrations exceeding ≈1,000 ppmv. Additional contributions from glaciers and ice sheet contributions to future sea level rise are uncertain but may equal or exceed several meters over the next millennium or longer. PMID:19179281

  9. Carbon dioxide and climate: an astrophysical perspective

    Energy Technology Data Exchange (ETDEWEB)

    Kandel, R S

    1979-01-01

    In this survey the earth is viewed from the astrophysical perspective, i.e. using global mean values of environmental parameters. The role of carbon dioxide is described in the processes of energy transfer from the earth's surface to space, which determine global climate as measured by the mean surface temperature. Analogies and differences between the problems of the terrestrial atmosphere and those of the solar and stellar atmospheres are examined, both in the computation of model atmospheres and in remote sensing of atmospheric temperature and composition. Subsequently, the temporal astrophysical perspective, with a review of the evolution of CO/sub 2/ abundance and climate on astrophysical or geological time scales, on earth as an Venus (the runaway greenhouse) and on Mars is introduced. Variation of CO/sub 2/ may have been critical to the maintenance of an environment in which life could originate and evolve, and may itself have been affected by life. On human time scales, the recent and continuing increase in atmospheric CO/sub 2/ raises new problems, which are briefly surveyed. It is argued, that the differential greenhouse effect of increased CO/sub 2/ in the earth's atmosphere is essentially identifical to the blanketing effect of spectral lines on the temperature structure of stellar atmospheres. The methods used by astrophysicists in such studies are reviewed and compared with those used to evaluate the differential greenhouse effect of CO/sub 2/ in radiative-convective models of the earth's atmosphere. The latter methods remain relatively crude, but recent results by different authors are in reasonably good agreement; however, the astrophysical perspective, i.e. the use of one-dimensional global mean models, remains a gross simplification of the real complexity of the earth's climate system, which is also true in stellar atmospheres.

  10. The climatic out of control. the climatic forcing

    International Nuclear Information System (INIS)

    Bony-Lena, S.; Dufresne, J.L.; Acot, P.; Friedlingstein, P.; Berger, A.; Loutre, M.L.; Raynaud, D.; Thuiller, W.; Le Treut, H.; Houssais, M.N.; Duplessy, J.C.; Royer, J.F.; Douville, H.; Barberousse, A.; Quinon, P.

    2007-01-01

    The expert group on the climate evolution affirms that the global warming is unequivocal and that the human being is the main responsible. This document broaches the climatic change under many aspects: the principle, the historical aspect of the greenhouse effect, the GIEC, the carbon cycle, the paleo-climate theory, the antarctic ices and the impacts of the climatic change on the biodiversity, the simulations and the models, the climatic indicators and the climatic forcing by human activities. (A.L.B.)

  11. Atmospheric carbon dioxide and the climate record

    International Nuclear Information System (INIS)

    Ellsaesser, H.W.

    1989-04-01

    This paper is an attempt to provide a summary review of conclusions from previous studies on this subject. Subject headings include: conceptualization of the greenhouse effect, the climatic effect of doubled CO 2 , interpretation of the climatic record, diagnosis of apparent and possible model deficiencies, and the palaeoclimatic record

  12. Atmospheric carbon dioxide and the climate record

    Energy Technology Data Exchange (ETDEWEB)

    Ellsaesser, H.W.

    1989-04-01

    This paper is an attempt to provide a summary review of conclusions from previous studies on this subject. Subject headings include: conceptualization of the greenhouse effect, the climatic effect of doubled CO/sub 2/, interpretation of the climatic record, diagnosis of apparent and possible model deficiencies, and the palaeoclimatic record.

  13. urbanization and climate chang carbon dioxide emission

    African Journals Online (AJOL)

    userpc

    t efficient public urban mass transit that involves low carbon emissi individual car usage should be discouraged. ent, automobile density, climate change, global warming, greenhou e change .... Lagos, Port Harcourt, Abuja and Kano (Federal.

  14. Irrigation as an Historical Climate Forcing

    Science.gov (United States)

    Cook, Benjamin I.; Shukla, Sonali P.; Puma, Michael J.; Nazarenko, Larissa S.

    2014-01-01

    Irrigation is the single largest anthropogenic water use, a modification of the land surface that significantly affects surface energy budgets, the water cycle, and climate. Irrigation, however, is typically not included in standard historical general circulation model (GCM) simulations along with other anthropogenic and natural forcings. To investigate the importance of irrigation as an anthropogenic climate forcing, we conduct two 5-member ensemble GCM experiments. Both are setup identical to the historical forced (anthropogenic plus natural) scenario used in version 5 of the Coupled Model Intercomparison Project, but in one experiment we also add water to the land surface using a dataset of historically estimated irrigation rates. Irrigation has a negligible effect on the global average radiative balance at the top of the atmosphere, but causes significant cooling of global average surface air temperatures over land and dampens regional warming trends. This cooling is regionally focused and is especially strong in Western North America, the Mediterranean, the Middle East, and Asia. Irrigation enhances cloud cover and precipitation in these same regions, except for summer in parts of Monsoon Asia, where irrigation causes a reduction in monsoon season precipitation. Irrigation cools the surface, reducing upward fluxes of longwave radiation (increasing net longwave), and increases cloud cover, enhancing shortwave reflection (reducing net shortwave). The relative magnitude of these two processes causes regional increases (northern India) or decreases (Central Asia, China) in energy availability at the surface and top of the atmosphere. Despite these changes in net radiation, however, climate responses are due primarily to larger magnitude shifts in the Bowen ratio from sensible to latent heating. Irrigation impacts on temperature, precipitation, and other climate variables are regionally significant, even while other anthropogenic forcings (anthropogenic aerosols

  15. How weather impacts the forced climate response

    Energy Technology Data Exchange (ETDEWEB)

    Kirtman, Ben P. [University of Miami, Division of Meteorology and Physical Oceanography, Rosenstiel School for Atmospheric and Marine Science, Miami, FL (United States); Center for Ocean-Land-Atmosphere Studies, Calverton, MD (United States); Schneider, Edwin K.; Straus, David M. [George Mason University, Department of Atmospheric, Oceanic and Earth Sciences, Fairfax, VA (United States); Center for Ocean-Land-Atmosphere Studies, Calverton, MD (United States); Min, Dughong; Burgman, Robert [University of Miami, Division of Meteorology and Physical Oceanography, Rosenstiel School for Atmospheric and Marine Science, Miami, FL (United States)

    2011-12-15

    The new interactive ensemble modeling strategy is used to diagnose how noise due to internal atmospheric dynamics impacts the forced climate response during the twentieth century (i.e., 1870-1999). The interactive ensemble uses multiple realizations of the atmospheric component model coupled to a single realization of the land, ocean and ice component models in order to reduce the noise due to internal atmospheric dynamics in the flux exchange at the interface of the component models. A control ensemble of so-called climate of the twentieth century simulations of the Community Climate Simulation Model version 3 (CCSM3) are compared with a similar simulation with the interactive ensemble version of CCSM3. Despite substantial differences in the overall mean climate, the global mean trends in surface temperature, 500 mb geopotential and precipitation are largely indistinguishable between the control ensemble and the interactive ensemble. Large differences in the forced response; however, are detected particularly in the surface temperature of the North Atlantic. Associated with the forced North Atlantic surface temperature differences are local differences in the forced precipitation and a substantial remote rainfall response in the deep tropical Pacific. We also introduce a simple variance analysis to separately compare the variance due to noise and the forced response. We find that the noise variance is decreased when external forcing is included. In terms of the forced variance, we find that the interactive ensemble increases this variance relative to the control. (orig.)

  16. Review of the recent carbon dioxide-climate controversy

    International Nuclear Information System (INIS)

    Luther, F.M.; Cess, R.D.

    1992-01-01

    Model calculations of the climatic impact of the increasing atmospheric carbon dioxide (CO 2 ) concentration consistently suggest that a doubling of the CO 2 concentration would lead to a warming of global average surface air temperatures by as much as several degrees Celsius. In this appendix, this controversy about the effect of CO 2 on climate is reviewed. Because the surface energy balance approach to estimating climate sensitivity has been the source of much of the controversy, a review of this approach is presented. It is shown that prior applications of this approach violate the law of conservation of energy (the first law of thermodynamics); therefore, these results are incorrect. Empirical data indicating the relationship between atmospheric emittance and surface vapor pressure and surface air temperature are shown to be consistent with climate model calculations. Consequently, it is not the experimental data that are the basis of the controversy, but rather the analysis and interpretation of these data

  17. The contribution of China's emissions to global climate forcing.

    Science.gov (United States)

    Li, Bengang; Gasser, Thomas; Ciais, Philippe; Piao, Shilong; Tao, Shu; Balkanski, Yves; Hauglustaine, Didier; Boisier, Juan-Pablo; Chen, Zhuo; Huang, Mengtian; Li, Laurent Zhaoxin; Li, Yue; Liu, Hongyan; Liu, Junfeng; Peng, Shushi; Shen, Zehao; Sun, Zhenzhong; Wang, Rong; Wang, Tao; Yin, Guodong; Yin, Yi; Zeng, Hui; Zeng, Zhenzhong; Zhou, Feng

    2016-03-17

    Knowledge of the contribution that individual countries have made to global radiative forcing is important to the implementation of the agreement on "common but differentiated responsibilities" reached by the United Nations Framework Convention on Climate Change. Over the past three decades, China has experienced rapid economic development, accompanied by increased emission of greenhouse gases, ozone precursors and aerosols, but the magnitude of the associated radiative forcing has remained unclear. Here we use a global coupled biogeochemistry-climate model and a chemistry and transport model to quantify China's present-day contribution to global radiative forcing due to well-mixed greenhouse gases, short-lived atmospheric climate forcers and land-use-induced regional surface albedo changes. We find that China contributes 10% ± 4% of the current global radiative forcing. China's relative contribution to the positive (warming) component of global radiative forcing, mainly induced by well-mixed greenhouse gases and black carbon aerosols, is 12% ± 2%. Its relative contribution to the negative (cooling) component is 15% ± 6%, dominated by the effect of sulfate and nitrate aerosols. China's strongest contributions are 0.16 ± 0.02 watts per square metre for CO2 from fossil fuel burning, 0.13 ± 0.05 watts per square metre for CH4, -0.11 ± 0.05 watts per square metre for sulfate aerosols, and 0.09 ± 0.06 watts per square metre for black carbon aerosols. China's eventual goal of improving air quality will result in changes in radiative forcing in the coming years: a reduction of sulfur dioxide emissions would drive a faster future warming, unless offset by larger reductions of radiative forcing from well-mixed greenhouse gases and black carbon.

  18. Modelling interactions of carbon dioxide, forests, and climate

    International Nuclear Information System (INIS)

    Luxmoore, R.J.; Baldocchi, D.D.

    1994-01-01

    Atmospheric carbon dioxide is rising and forests and climate is changing exclamation point This combination of fact and premise may be evaluated at a range of temporal and spatial scales with the aid of computer simulators describing the interrelationships between forest vegetation, litter and soil characteristics, and appropriate meteorological variables. Some insights on the effects of climate on the transfers of carbon and the converse effect of carbon transfer on climate are discussed as a basis for assessing the significance of feedbacks between vegetation and climate under conditions of rising atmospheric carbon dioxide. Three main classes of forest models are reviewed. These are physiologically-based models, forest succession simulators based on the JABOWA model, and ecosystem-carbon budget models that use compartment transfer rates with empirically estimated coefficients. Some regression modeling approaches are also outlined. Energy budget models applied to forests and grasslands are also reviewed. This review presents examples of forest models; a comprehensive discussion of all available models is not undertaken

  19. Attribution of climate forcing to economic sectors.

    Science.gov (United States)

    Unger, Nadine; Bond, Tami C; Wang, James S; Koch, Dorothy M; Menon, Surabi; Shindell, Drew T; Bauer, Susanne

    2010-02-23

    A much-cited bar chart provided by the Intergovernmental Panel on Climate Change displays the climate impact, as expressed by radiative forcing in watts per meter squared, of individual chemical species. The organization of the chart reflects the history of atmospheric chemistry, in which investigators typically focused on a single species of interest. However, changes in pollutant emissions and concentrations are a symptom, not a cause, of the primary driver of anthropogenic climate change: human activity. In this paper, we suggest organizing the bar chart according to drivers of change-that is, by economic sector. Climate impacts of tropospheric ozone, fine aerosols, aerosol-cloud interactions, methane, and long-lived greenhouse gases are considered. We quantify the future evolution of the total radiative forcing due to perpetual constant year 2000 emissions by sector, most relevant for the development of climate policy now, and focus on two specific time points, near-term at 2020 and long-term at 2100. Because sector profiles differ greatly, this approach fosters the development of smart climate policy and is useful to identify effective opportunities for rapid mitigation of anthropogenic radiative forcing.

  20. Anthropogenic radiative forcing of southern African and Southern Hemisphere climate variability and change

    CSIR Research Space (South Africa)

    Engelbrecht, FA

    2014-10-01

    Full Text Available of stratospheric ozone, greenhouse gasses, aerosols and sulphur dioxide, can improve the model's skill to simulate inter-annual variability over southern Africa. The paper secondly explores the role of different radiative forcings of future climate change over...

  1. Climatic response to a gradual increase of atmospheric carbon dioxide

    International Nuclear Information System (INIS)

    Stouffer, R.J.; Manabe, S.; Bryan, K.

    1990-01-01

    The transient response of a coupled ocean-atmosphere model to an increase of carbon dioxide has been the subject of several studies. The models used in these studies explicitly incorporate the effect of heat transport by ocean currents and are different from the model used by Hansen et al. Here the authors evaluate the climatic influence of increasing atmospheric carbon dioxide using a coupled model recently developed at the NOAA Geophysical Fluid Dynamics Laboratory. The model response exhibits a marked and unexpected interhemispheric asymmetry. In the circumpolar ocean of the southern hemisphere, a region of deep vertical mixing, the increase of surface air temperature is very slow. In the Northern hemisphere of the model, the rise of surface air temperature is faster and increases with latitude, with the exception of the northern North Atlantic, where it is relatively slow because of the weakening of the thermohaline circulation

  2. Climate Sensitivity, Sea Level, and Atmospheric Carbon Dioxide

    Science.gov (United States)

    Hansen, James; Sato, Makiko; Russell, Gary; Kharecha, Pushker

    2013-01-01

    Cenozoic temperature, sea level and CO2 covariations provide insights into climate sensitivity to external forcings and sea-level sensitivity to climate change. Climate sensitivity depends on the initial climate state, but potentially can be accurately inferred from precise palaeoclimate data. Pleistocene climate oscillations yield a fast-feedback climate sensitivity of 3+/-1deg C for a 4 W/sq m CO2 forcing if Holocene warming relative to the Last Glacial Maximum (LGM) is used as calibration, but the error (uncertainty) is substantial and partly subjective because of poorly defined LGM global temperature and possible human influences in the Holocene. Glacial-to-interglacial climate change leading to the prior (Eemian) interglacial is less ambiguous and implies a sensitivity in the upper part of the above range, i.e. 3-4deg C for a 4 W/sq m CO2 forcing. Slow feedbacks, especially change of ice sheet size and atmospheric CO2, amplify the total Earth system sensitivity by an amount that depends on the time scale considered. Ice sheet response time is poorly defined, but we show that the slow response and hysteresis in prevailing ice sheet models are exaggerated. We use a global model, simplified to essential processes, to investigate state dependence of climate sensitivity, finding an increased sensitivity towards warmer climates, as low cloud cover is diminished and increased water vapour elevates the tropopause. Burning all fossil fuels, we conclude, would make most of the planet uninhabitable by humans, thus calling into question strategies that emphasize adaptation to climate change.

  3. Carbon Dioxide Physiological Forcing Dominates Projected Eastern Amazonian Drying

    Science.gov (United States)

    Richardson, T. B.; Forster, P. M.; Andrews, T.; Boucher, O.; Faluvegi, G.; Fläschner, D.; Kasoar, M.; Kirkevâg, A.; Lamarque, J.-F.; Myhre, G.; Olivié, D.; Samset, B. H.; Shawki, D.; Shindell, D.; Takemura, T.; Voulgarakis, A.

    2018-03-01

    Future projections of east Amazonian precipitation indicate drying, but they are uncertain and poorly understood. In this study we analyze the Amazonian precipitation response to individual atmospheric forcings using a number of global climate models. Black carbon is found to drive reduced precipitation over the Amazon due to temperature-driven circulation changes, but the magnitude is uncertain. CO2 drives reductions in precipitation concentrated in the east, mainly due to a robustly negative, but highly variable in magnitude, fast response. We find that the physiological effect of CO2 on plant stomata is the dominant driver of the fast response due to reduced latent heating and also contributes to the large model spread. Using a simple model, we show that CO2 physiological effects dominate future multimodel mean precipitation projections over the Amazon. However, in individual models temperature-driven changes can be large, but due to little agreement, they largely cancel out in the model mean.

  4. More carbon dioxide is a result of climatic change, not a cause. Independent scientists correct KNMI and IPCC

    International Nuclear Information System (INIS)

    Voortman, A.J.

    2004-01-01

    Attention is paid to opponents of the carbon dioxide hypothesis, supported by the Intergovernmental Panel on Climatic Change (IPCC), in which it is stated that climatic change is caused by an increase of carbon dioxide in the atmosphere [nl

  5. Sulfur dioxide initiates global climate change in four ways

    International Nuclear Information System (INIS)

    Ward, Peter L.

    2009-01-01

    Global climate change, prior to the 20th century, appears to have been initiated primarily by major changes in volcanic activity. Sulfur dioxide (SO 2 ) is the most voluminous chemically active gas emitted by volcanoes and is readily oxidized to sulfuric acid normally within weeks. But trace amounts of SO 2 exert significant influence on climate. All major historic volcanic eruptions have formed sulfuric acid aerosols in the lower stratosphere that cooled the earth's surface ∼ 0.5 o C for typically three years. While such events are currently happening once every 80 years, there are times in geologic history when they occurred every few to a dozen years. These were times when the earth was cooled incrementally into major ice ages. There have also been two dozen times during the past 46,000 years when major volcanic eruptions occurred every year or two or even several times per year for decades. Each of these times was contemporaneous with very rapid global warming. Large volumes of SO 2 erupted frequently appear to overdrive the oxidizing capacity of the atmosphere resulting in very rapid warming. Such warming and associated acid rain becomes extreme when millions of cubic kilometers of basalt are erupted in much less than one million years. These are the times of the greatest mass extinctions. When major volcanic eruptions do not occur for decades to hundreds of years, the atmosphere can oxidize all pollutants, leading to a very thin atmosphere, global cooling and decadal drought. Prior to the 20th century, increases in atmospheric carbon dioxide (CO 2 ) followed increases in temperature initiated by changes in SO 2 . By 1962, man burning fossil fuels was adding SO 2 to the atmosphere at a rate equivalent to one 'large' volcanic eruption each 1.7 years. Global temperatures increased slowly from 1890 to 1950 as anthropogenic sulfur increased slowly. Global temperatures increased more rapidly after 1950 as the rate of anthropogenic sulfur emissions increased. By

  6. Carbon Dioxide Effects Research and Assessment Program: Proceedings of the carbon dioxide and climate research program conference

    Energy Technology Data Exchange (ETDEWEB)

    Schmitt, L E [ed.

    1980-12-01

    Papers presented at the Carbon Dioxide and Climate Research Program Conference are included in this volume. Topics discussed are: the carbon cycle; modeling the carbon system; climatic response due to increased CO2; climate modeling; the use of paleoclimatic data in understanding climate change; attitudes and implications of CO2; social responses to the CO2 problem; a scenario for atmospheric CO2 to 2025; marine photosynthesis and the global carbon cycle; and the role of tropical forests in the carbon balance of the world. Separate abstracts of nine papers have been prepared for inclusion in the Energy Data Base. (RJC)

  7. Rightsizing expectations for carbon dioxide removal towards ambitious climate goals

    Science.gov (United States)

    Mach, K. J.; Field, C. B.

    2017-12-01

    Proven approaches for reducing heat-trapping emissions are increasingly cost competitive and feasible at scale. Such approaches include renewable-energy technologies, energy efficiency, reduced deforestation, and abatement of industrial and agricultural emissions. Their pace of deployment, though, is far from sufficient to limit warming well below 2°C above preindustrial levels, the goal of the Paris Agreement. Against this backdrop, technologies for carbon removal are increasingly asserted as key to climate policy. Carbon dioxide removal (CDR), or negative emissions, technologies can compensate for ongoing emissions, helping keep ambitious warming limits in reach. The dramatic rise of CDR approaches in analysis and planning towards ambitious climate goals, however, has stirred up discomfort and debate. Focusing on rightsizing CDR expectations, this presentation will first briefly reflect on the status of the suite of CDR possibilities. The options include strategies grounded in improved ecosystem stewardship (e.g., reforestation and afforestation, conservation agriculture); strategies that are also biomass-based but with more engineering and more trade-offs (e.g., biochar additions to soils, bioenergy with carbon capture and storage); and engineered, nonbiological approaches (e.g., enhanced weathering, direct air capture). Second, the presentation will evaluate constraints surrounding CDR deployment at large scale and in peak-and-decline scenarios. These constraints involve, for example, unprecedented rates of land transformation in climate change mitigation pathways limiting warming to 2°C with high probability. They also entail the substantial, little studied risks of scenarios with temperatures peaking and then declining. Third, the presentation will review emerging lessons from CDR implementation to date, such as in legally enforceable forest-offset projects, along with near-term opportunities for catalyzing CDR, such as through low-cost opportunities for

  8. Influence of carbon dioxide clouds on early martian climate.

    Science.gov (United States)

    Mischna, M A; Kasting, J F; Pavlov, A; Freedman, R

    2000-06-01

    Recent studies have shown that clouds made of carbon dioxide ice may have warmed the surface of early Mars by reflecting not only incoming solar radiation but upwelling IR radiation as well. However, these studies have not treated scattering self-consistently in the thermal IR. Our own calculations, which treat IR scattering properly, confirm these earlier calculations but show that CO2 clouds can also cool the surface, especially if they are low and optically thick. Estimating the actual effect of CO2 clouds on early martian climate will require three-dimensional models in which cloud location, height, and optical depth, as well as surface temperature and pressure, are determined self-consistently. Our calculations further confirm that CO2 clouds should extend the outer boundary of the habitable zone around a star but that there is still a finite limit beyond which above-freezing surface temperatures cannot be maintained by a CO2-H2O atmosphere. For our own Solar System, the absolute outer edge of the habitable zone is at approximately 2.4 AU.

  9. Air pollution and climate-forcing impacts of a global hydrogen economy.

    Science.gov (United States)

    Schultz, Martin G; Diehl, Thomas; Brasseur, Guy P; Zittel, Werner

    2003-10-24

    If today's surface traffic fleet were powered entirely by hydrogen fuel cell technology, anthropogenic emissions of the ozone precursors nitrogen oxide (NOx) and carbon monoxide could be reduced by up to 50%, leading to significant improvements in air quality throughout the Northern Hemisphere. Model simulations of such a scenario predict a decrease in global OH and an increased lifetime of methane, caused primarily by the reduction of the NOx emissions. The sign of the change in climate forcing caused by carbon dioxide and methane depends on the technology used to generate the molecular hydrogen. A possible rise in atmospheric hydrogen concentrations is unlikely to cause significant perturbations of the climate system.

  10. Climate forcing growth rates: doubling down on our Faustian bargain

    Science.gov (United States)

    Hansen, James; Kharecha, Pushker; Sato, Makiko

    2013-03-01

    Rahmstorf et al 's (2012) conclusion that observed climate change is comparable to projections, and in some cases exceeds projections, allows further inferences if we can quantify changing climate forcings and compare those with projections. The largest climate forcing is caused by well-mixed long-lived greenhouse gases. Here we illustrate trends of these gases and their climate forcings, and we discuss implications. We focus on quantities that are accurately measured, and we include comparison with fixed scenarios, which helps reduce common misimpressions about how climate forcings are changing. Annual fossil fuel CO2 emissions have shot up in the past decade at about 3% yr-1, double the rate of the prior three decades (figure 1). The growth rate falls above the range of the IPCC (2001) 'Marker' scenarios, although emissions are still within the entire range considered by the IPCC SRES (2000). The surge in emissions is due to increased coal use (blue curve in figure 1), which now accounts for more than 40% of fossil fuel CO2 emissions. Figure 1. Figure 1. CO2 annual emissions from fossil fuel use and cement manufacture, an update of figure 16 of Hansen (2003) using data of British Petroleum (BP 2012) concatenated with data of Boden et al (2012). The resulting annual increase of atmospheric CO2 (12-month running mean) has grown from less than 1 ppm yr-1 in the early 1960s to an average ~2 ppm yr-1 in the past decade (figure 2). Although CO2 measurements were not made at sufficient locations prior to the early 1980s to calculate the global mean change, the close match of global and Mauna Loa data for later years suggests that Mauna Loa data provide a good approximation of global change (figure 2), thus allowing a useful estimate of annual global change beginning with the initiation of Mauna Loa measurements in 1958 by Keeling et al (1973). Figure 2. Figure 2. Annual increase of CO2 based on data from the NOAA Earth System Research Laboratory (ESRL 2012). CO2 change

  11. The climatic out of control. the climatic forcing; L'emballement climatique. Le forcage climatique

    Energy Technology Data Exchange (ETDEWEB)

    Bony-Lena, S.; Dufresne, J.L. [Laboratoire de Meteorologie Dynamique, LMD/IPSL, CNRS-UPMC, 75 - Paris (France); Acot, P. [Institut d' histoire et de philosophie des sciences et des techniques (IHPST), CNRS-Univ. Paris-1-ENS, 75 - Paris (France); Friedlingstein, P. [CEA Saclay, Lab. des Sciences du Climat et l' Environnement (LSCE), 91 - Gif-sur-Yvette (France); Berger, A.; Loutre, M.L. [Universite Catholique de Louvain (UCL), Louvain-la-Neuve (Belgium). Inst. d' Astronomie et de Geophysique G. Lemaitre; Jouzel, J. [Institut Pierre Simon Laplace, 75 - Paris (France); Raynaud, D. [Laboratoire de Glaciologie et Geophysique de l' Environnement (UMR 5183), 38 - Saint Martin d' Heres cedex (France); Thuiller, W. [Universite Joseph-Fourier, Lab. d' Ecologie Alpine, CNRS-Univ. Grenoble-1, 38 (France); Le Treut, H. [Laboratoire de Meteorologie dynamique du CNRS, 75 - Paris (France); Houssais, M.N. [Laboratoire d' Oceanographie et du Climat Experimentation et Approches Numerique (LOCEAN / IPSL), 75 - Paris (France); Duplessy, J.C. [Centre National de la Recherche Scientifique, Laboratoire des Sciences du Climat et de l' Environnement (LSCE), 91 - Gif sur Yvette (France); Royer, J.F.; Douville, H. [Centre National de Recherches Meteorologiques, 31 - Toulouse (France); Barberousse, A. [Institut d' Histoire et de Philosophie des Sciences et des Techniques, CNRS, ENS, 75 - Paris (France); Quinon, P

    2007-03-15

    The expert group on the climate evolution affirms that the global warming is unequivocal and that the human being is the main responsible. This document broaches the climatic change under many aspects: the principle, the historical aspect of the greenhouse effect, the GIEC, the carbon cycle, the paleo-climate theory, the antarctic ices and the impacts of the climatic change on the biodiversity, the simulations and the models, the climatic indicators and the climatic forcing by human activities. (A.L.B.)

  12. Feedback mechanisms in the climate system affecting future levels of carbon dioxide

    International Nuclear Information System (INIS)

    Kellogg, W.W.

    1983-01-01

    The rate of increase of concentration of atmospheric carbon dioxide depends on the consumption of fossil fuels (the major source of 'new' carbon dioxide) and the natural sinks for this trace constituent, primarily the oceans and the biosphere. (It is now fairly well established that the biosphere cannot be a major source, as has been claimed.) The rate of operation of these sinks depends on several factors determined by the state of the climate system, and they will therefore presumably change as the greenhouse effect of increasing carbon dioxide warms the earth. Five specific feedback loops are discussed, two of which are positive (amplifying the rate of increase), two are weakly negative (damping the rate of increase), and one is indeterminate but probably positive. It is concluded that it would be well to be prepared for the possibility that carbon dioxide may increase faster than predicted by models based on the current or past state of the climate system

  13. The carbon dioxide content in ice cores - climatic curves of carbon dioxide. Zu den CO sub 2 -Klimakurven aus Eisbohrkernen

    Energy Technology Data Exchange (ETDEWEB)

    Heyke, H.E.

    1992-05-01

    The 'greenhouse effect', which implies a temperature of 15 deg C as against -18 deg C, owes its effect to 80% from water (clouds and gaseous phase) and to 10% from carbon dioxide, besides other components. Whereas water is largely unaccounted for, carbon dioxide has been postulated as the main cause of anticipated climatic catastrophe. The carbon dioxide concentration in the atmosphere has risen presently to such levels that all previous figures seem to have been left far behind. The reference point is the concentration of carbon dioxide in the air bubbles trapped in ice cores of Antartic and Greenland ice dated 160 000 years ago, which show much lower values than at present. A review of the most relevant publications indicates that many basic laws of chemistry seem to have been left largely unconsidered and experimental errors have made the results rather doubtful. Appropriate arguments have been presented. The investigations considered should be repeated under improved and more careful conditions. (orig.).

  14. A Sulfur Dioxide Climate Feedback on Early Mars

    Science.gov (United States)

    Halevy, I.; Pierrehumbert, R. T.; Schrag, D. P.

    2007-12-01

    Reconciling evidence for persistent liquid water during the late Noachian with our understanding of the evolution of the Martian atmosphere and of solar luminosity remains a challenge, despite several decades of research. An optically-thicker atmosphere to supply the necessary radiative forcing would result in the existence of a carbon cycle similar to Earth's, where the release of CO2 from volcanoes is balanced by burial of calcium carbonate through silicate weathering reactions that remove protons and release alkalinity to surface waters. Existence of such a carbon cycle on Mars, even for tens of millions of years, would yield carbonate sediments in far greater abundance than has been observed, as well as residual clay minerals. The high concentration of sulfur in Martian soils and rocks indicates that Martian volcanic emissions contained abundant sulfur volatiles in addition to CO2. However, the atmospheric and aquatic chemistry of SO2 under the reducing conditions of early Mars, in contrast with the presently oxidizing and biologically-catalyzed Earth, has not been thoroughly examined. We argue that these conditions may have allowed atmospheric concentrations of SO2 high enough to augment a thick CO2-H2O greenhouse. Furthermore, early Martian climate may have been stabilized by a feedback mechanism involving SO2 and the solubility of sulfite minerals instead of CO2 and the solubility of carbonates. We present the results of a one-dimensional radiative-convective model, demonstrating the radiative importance of SO2 to the planetary energy budget. We also use a simple geochemical model to show that the presence of SO2 in the early Martian atmosphere would have dominated the aquatic chemistry on the planet's surface, and may provide an explanation for how water could have persisted for millions of years without forming massive carbonate sediments, yet allowing the formation of clay minerals.

  15. Detecting the climatic effects of increasing carbon dioxide

    Energy Technology Data Exchange (ETDEWEB)

    MacCracken, M C; Luther, F M [eds.

    1985-12-01

    This report documents what is known about detecting the CO2-induced changes in climate, and describes the uncertainties and unknowns associated with this monitoring and analysis effort. The various approaches for detecting CO2-induced climate changes are discussed first, followed by a review of applications of these strategies to the various climatic variables that are expected to be changing. Recommendations are presented for research and analysis activities. Separate abstracts have been prepared for the individual papers. (ACR)

  16. Climate forcings and climate sensitivities diagnosed from atmospheric global circulation models

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Bruce T. [Boston University, Department of Geography and Environment, Boston, MA (United States); Knight, Jeff R.; Ringer, Mark A. [Met Office Hadley Centre, Exeter (United Kingdom); Deser, Clara; Phillips, Adam S. [National Center for Atmospheric Research, Boulder, CO (United States); Yoon, Jin-Ho [University of Maryland, Cooperative Institute for Climate and Satellites, Earth System Science Interdisciplinary Center, College Park, MD (United States); Cherchi, Annalisa [Centro Euro-Mediterraneo per i Cambiamenti Climatici, and Istituto Nazionale di Geofisica e Vulcanologia, Bologna (Italy)

    2010-12-15

    Understanding the historical and future response of the global climate system to anthropogenic emissions of radiatively active atmospheric constituents has become a timely and compelling concern. At present, however, there are uncertainties in: the total radiative forcing associated with changes in the chemical composition of the atmosphere; the effective forcing applied to the climate system resulting from a (temporary) reduction via ocean-heat uptake; and the strength of the climate feedbacks that subsequently modify this forcing. Here a set of analyses derived from atmospheric general circulation model simulations are used to estimate the effective and total radiative forcing of the observed climate system due to anthropogenic emissions over the last 50 years of the twentieth century. They are also used to estimate the sensitivity of the observed climate system to these emissions, as well as the expected change in global surface temperatures once the climate system returns to radiative equilibrium. Results indicate that estimates of the effective radiative forcing and total radiative forcing associated with historical anthropogenic emissions differ across models. In addition estimates of the historical sensitivity of the climate to these emissions differ across models. However, results suggest that the variations in climate sensitivity and total climate forcing are not independent, and that the two vary inversely with respect to one another. As such, expected equilibrium temperature changes, which are given by the product of the total radiative forcing and the climate sensitivity, are relatively constant between models, particularly in comparison to results in which the total radiative forcing is assumed constant. Implications of these results for projected future climate forcings and subsequent responses are also discussed. (orig.)

  17. Carbon dioxide and climate: too much heat clouds debate

    Energy Technology Data Exchange (ETDEWEB)

    Gribben, J

    1978-12-01

    Technical feature:The possibility of a significant global warming as a result of increased atmospheric carbon dioxide from the burning of fossil fuels (the greenhouse effect) has recently received attention from climatologists and energy policy planners. The greenhouse effect has been used by the pro-nuclear lobby as an argument in favor of a massive commitment to nuclear power generation. While the CO2 problem is real, the solution does not lie in an energy strategy based on nuclear power, which involves as yet unsolved problems of radioactive waste disposal. The economic feasibility of processes for removing CO2 from waste gases should be investigated. (4 graphs, 10 references)

  18. Implications for Climate Sensitivity from the Response to Individual Forcings

    Science.gov (United States)

    Marvel, Kate; Schmidt, Gavin A.; Miller, Ron L.; Nazarenko, Larissa

    2015-01-01

    Climate sensitivity to doubled CO2 is a widely-used metric of the large-scale response to external forcing. Climate models predict a wide range for two commonly used definitions: the transient climate response (TCR: the warming after 70 years of CO2 concentrations that riseat 1 per year), and the equilibrium climate sensitivity (ECS: the equilibrium temperature change following a doubling of CO2 concentrations). Many observational datasets have been used to constrain these values, including temperature trends over the recent past 16, inferences from paleo-climate and process-based constraints from the modern satellite eras. However, as the IPCC recently reported different classes of observational constraints produce somewhat incongruent ranges. Here we show that climate sensitivity estimates derived from recent observations must account for the efficacy of each forcing active during the historical period. When we use single forcing experiments to estimate these efficacies and calculate climate sensitivity from the observed twentieth-century warming, our estimates of both TCR and ECS are revised upward compared to previous studies, improving the consistency with independent constraints.

  19. The contribution of China’s emissions to global climate forcing

    Science.gov (United States)

    Li, Bengang; Gasser, Thomas; Ciais, Philippe; Piao, Shilong; Tao, Shu; Balkanski, Yves; Hauglustaine, Didier; Boisier, Juan-Pablo; Chen, Zhuo; Huang, Mengtian; Li, Laurent Zhaoxin; Li, Yue; Liu, Hongyan; Liu, Junfeng; Peng, Shushi; Shen, Zehao; Sun, Zhenzhong; Wang, Rong; Wang, Tao; Yin, Guodong; Yin, Yi; Zeng, Hui; Zeng, Zhenzhong; Zhou, Feng

    2016-03-01

    Knowledge of the contribution that individual countries have made to global radiative forcing is important to the implementation of the agreement on “common but differentiated responsibilities” reached by the United Nations Framework Convention on Climate Change. Over the past three decades, China has experienced rapid economic development, accompanied by increased emission of greenhouse gases, ozone precursors and aerosols, but the magnitude of the associated radiative forcing has remained unclear. Here we use a global coupled biogeochemistry-climate model and a chemistry and transport model to quantify China’s present-day contribution to global radiative forcing due to well-mixed greenhouse gases, short-lived atmospheric climate forcers and land-use-induced regional surface albedo changes. We find that China contributes 10% ± 4% of the current global radiative forcing. China’s relative contribution to the positive (warming) component of global radiative forcing, mainly induced by well-mixed greenhouse gases and black carbon aerosols, is 12% ± 2%. Its relative contribution to the negative (cooling) component is 15% ± 6%, dominated by the effect of sulfate and nitrate aerosols. China’s strongest contributions are 0.16 ± 0.02 watts per square metre for CO2 from fossil fuel burning, 0.13 ± 0.05 watts per square metre for CH4, -0.11 ± 0.05 watts per square metre for sulfate aerosols, and 0.09 ± 0.06 watts per square metre for black carbon aerosols. China’s eventual goal of improving air quality will result in changes in radiative forcing in the coming years: a reduction of sulfur dioxide emissions would drive a faster future warming, unless offset by larger reductions of radiative forcing from well-mixed greenhouse gases and black carbon.

  20. Sensitivity of regional climate to global temperature and forcing

    International Nuclear Information System (INIS)

    Tebaldi, Claudia; O’Neill, Brian; Lamarque, Jean-François

    2015-01-01

    The sensitivity of regional climate to global average radiative forcing and temperature change is important for setting global climate policy targets and designing scenarios. Setting effective policy targets requires an understanding of the consequences exceeding them, even by small amounts, and the effective design of sets of scenarios requires the knowledge of how different emissions, concentrations, or forcing need to be in order to produce substantial differences in climate outcomes. Using an extensive database of climate model simulations, we quantify how differences in global average quantities relate to differences in both the spatial extent and magnitude of climate outcomes at regional (250–1250 km) scales. We show that differences of about 0.3 °C in global average temperature are required to generate statistically significant changes in regional annual average temperature over more than half of the Earth’s land surface. A global difference of 0.8 °C is necessary to produce regional warming over half the land surface that is not only significant but reaches at least 1 °C. As much as 2.5 to 3 °C is required for a statistically significant change in regional annual average precipitation that is equally pervasive. Global average temperature change provides a better metric than radiative forcing for indicating differences in regional climate outcomes due to the path dependency of the effects of radiative forcing. For example, a difference in radiative forcing of 0.5 W m −2 can produce statistically significant differences in regional temperature over an area that ranges between 30% and 85% of the land surface, depending on the forcing pathway. (letter)

  1. Projecting the climatic effects of increasing carbon dioxide

    Energy Technology Data Exchange (ETDEWEB)

    MacCracken, M C; Luther, F M [eds.

    1985-12-01

    This report presents the current knowns, unknowns, and uncertainties regarding the projected climate changes that might occur as a result of an increasing atmospheric CO/sub 2/ concentration. Further, the volume describes what research is required to estimate the magnitude and rate of a CO/sub 2/-induced clamate change with regional and seasonal resolution. Separate abstracts have been prepared for the individual papers. (ACR)

  2. Reducing the rate of carbon dioxide buildup with biomass fuel under climate change

    International Nuclear Information System (INIS)

    Peart, R.; Curry, R.; Jones, J.; Boote, K.; Allen, L.

    1993-01-01

    The authors have been working for several years on estimating, through crop simulation and crop growth chamber experiments, the changes in yield and in irrigation demand which would be brought about by a doubling of atmospheric greenhouse gases, given the results of three General Circulation Models (GCM) that simulate the climate change that would be expected. They are now beginning to study the impact this might have in relation to biomass fuels. An important question is the effect of the changed climate on crop production, would the increased carbon dioxide concentration outweigh the negative climate change effects on crop yields? Results are quite variable due to different climate change effects at different locations and the differences in historical weather and in soils in different locations. However, on balance, climate change would result in reduced yields of the crops we studied, soybean, maize and peanut. However, US production of these crops could be maintained or increased by the use of irrigation on more acres. Irrigated crops, in general, would have increased yields under climate change because of the increased photosynthetic efficiency with higher carbon dioxide levels. Results on net remediation of carbon dioxide buildup by the use of biomass fuel rather than fossil fuel are not completed, but previous work has shown that Midwest non-irrigated maize production provides much more equivalent biomass energy than is required for its production. The studies with soybean show a ratio of equivalent energy output in the seed to energy used in producing the crop ranging from 4 to almost 9 under climate change

  3. Forcings and feedbacks by land ecosystem changes on climate change

    Science.gov (United States)

    Betts, R. A.

    2006-12-01

    Vegetation change is involved in climate change through both forcing and feedback processes. Emissions of CO{2} from past net deforestation are estimated to have contributed approximately 0.22 0.51 Wm - 2 to the overall 1.46 Wm - 2 radiative forcing by anthropogenic increases in CO{2} up to the year 2000. Deforestation-induced increases in global mean surface albedo are estimated to exert a radiative forcing of 0 to -0.2 Wm - 2, and dust emissions from land use may exert a radiative forcing of between approximately +0.1 and -0.2 Wm - 2. Changes in the fluxes of latent and sensible heat due to tropical deforestation are simulated to have exerted other local warming effects which cannot be quantified in terms of a Wm - 2 radiative forcing, with the potential for remote effects through changes in atmospheric circulation. With tropical deforestation continuing rapidly, radiative forcing by surface albedo change may become less useful as a measure of the forcing of climate change by changes in the physical properties of the land surface. Although net global deforestation is continuing, future scenarios used for climate change prediction suggest that fossil fuel emissions of CO{2} may continue to increase at a greater rate than land use emissions and therefore continue to increase in dominance as the main radiative forcing. The CO{2} rise may be accelerated by up to 66% by feedbacks arising from global soil carbon loss and forest dieback in Amazonia as a consequence of climate change, and Amazon forest dieback may also exert feedbacks through changes in the local water cycle and increases in dust emissions.

  4. Climate Implications of the Heterogeneity of Anthropogenic Aerosol Forcing

    Science.gov (United States)

    Persad, Geeta Gayatri

    Short-lived anthropogenic aerosols are concentrated in regions of high human activity, where they interact with radiation and clouds, causing horizontally heterogeneous radiative forcing between polluted and unpolluted regions. Aerosols can absorb shortwave energy in the atmosphere, but deplete it at the surface, producing opposite radiative perturbations between the surface and atmosphere. This thesis investigates climate and policy implications of this horizontal and vertical heterogeneity of anthropogenic aerosol forcing, employing the Geophysical Fluid Dynamics Laboratory's AM2.1 and AM3 models, both at a global scale and using East Asia as a regional case study. The degree of difference between spatial patterns of climate change due to heterogeneous aerosol forcing versus homogeneous greenhouse gas forcing deeply impacts the detection, attribution, and prediction of regional climate change. This dissertation addresses a gap in current understanding of these two forcings' response pattern development, using AM2.1 historical forcing simulations. The results indicate that fast atmospheric and land-surface processes alone substantially homogenize the global pattern of surface energy flux response to heterogeneous aerosol forcing. Aerosols' vertical redistribution of energy significantly impacts regional climate, but is incompletely understood. It is newly identified here, via observations and historical and idealized forcing simulations, that increased aerosol-driven atmospheric absorption may explain half of East Asia's recent surface insolation decline. Further, aerosols' surface and atmospheric effects counteract each other regionally---atmospheric heating enhances summer monsoon circulation, while surface dimming suppresses it---but absorbing aerosols' combined effects reduce summer monsoon rainfall. This thesis constitutes the first vertical decomposition of aerosols' impacts in this high-emissions region and elucidates the monsoonal response to aerosols

  5. Impact of Dust Radiative Forcing upon Climate. Chapter 13

    Science.gov (United States)

    Miller, Ronald L.; Knippertz, Peter; Perez Garcia-Pando, Carlos; Perlwitz, Jan P.; Tegan, Ina

    2014-01-01

    Dust aerosols perturb the atmospheric radiative flux at both solar and thermal wavelengths, altering the energy and water cycles. The climate adjusts by redistributing energy and moisture, so that local temperature perturbations, for example, depend upon the forcing over the entire extent of the perturbed circulation. Within regions frequently mixed by deep convection, including the deep tropics, dust particles perturb the surface air temperature primarily through radiative forcing at the top of the atmosphere (TOA). Many models predict that dust reduces global precipitation. This reduction is typically attributed to the decrease of surface evaporation in response to dimming of the surface. A counterexample is presented, where greater shortwave absorption by dust increases evaporation and precipitation despite greater dimming of the surface. This is attributed to the dependence of surface evaporation upon TOA forcing through its influence upon surface temperature and humidity. Perturbations by dust to the surface wind speed and vegetation (through precipitation anomalies) feed back upon the dust aerosol concentration. The current uncertainty of radiative forcing attributed to dust and the resulting range of climate perturbations calculated by models remain a useful test of our understanding of the mechanisms relating dust radiative forcing to the climate response.

  6. Future Climate Forcings and Olive Yield in a Mediterranean Orchard

    Directory of Open Access Journals (Sweden)

    Francesco Viola

    2014-05-01

    Full Text Available The olive tree is one of the most characteristic rainfed trees in the Mediterranean region. Observed and forecasted climate modifications in this region, such as the CO2 concentration and temperature increase and the net radiation, rainfall and wind speed decrease, will likely alter vegetation water stress and modify productivity. In order to simulate how climatic change could alter soil moisture dynamic, biomass growth and fruit productivity, a water-driven crop model has been used in this study. The numerical model, previously calibrated on an olive orchard located in Sicily (Italy with a satisfactory reproduction of historical olive yield data, has been forced with future climate scenarios generated using a stochastic weather generator and a downscaling procedure of an ensemble of climate model outputs. The stochastic downscaling is carried out using simulations of some General Circulation Models adopted in the fourth Intergovernmental Panel on Climate Change (IPCC assessment report (4AR for future scenarios. The outcomes state that climatic forcings driving potential evapotranspiration compensate for each other, resulting in a slight increase of this water demand flux; moreover, the increase of CO2 concentration leads to a potential assimilation increase and, consequently, to an overall productivity increase in spite of the growth of water stress due to the rainfall reduction.

  7. Visualization study for forced convection heat transfer of supercritical carbon dioxide near pseudo-boiling point

    International Nuclear Information System (INIS)

    Sakurai, K.; Ko, H.S.; Okamoto, K.; Madarame, H.

    2001-01-01

    For development of new reactor, supercritical water is expected to be used as coolant to improve thermal efficiency. However, the thermal characteristics of supercritical fluid is not revealed completely because its difficulty for experiment. Specific phenomena tend to occur near the pseudo-boiling point which is characterised by temperature corresponding to the saturation point in ordinary fluid. Around this point, the physic properties such as density, specific heat and thermal conductivity are drastically varying. Although there is no difference between gas and liquid phases in supercritical fluids, phenomena similar to boiling (with heat transfer deterioration) can be observed round the pseudo-boiling point. Experiments of heat transfer have been done for supercritical fluid in forced convective condition. However, these experiments were mainly realised inside stainless steel cylinder pipes, for which flow visualisation is difficult. Consequently, this work has been devoted to the development of method allowing the visualisation of supercritical flows. The experiment setup is composed of main loop and test section for the visualisation. Carbon dioxide is used as test fluid. Supercritical carbon dioxide flows upward in rectangular channel and heated by one-side wall to generate forced convection heat transfer. Through window at mid-height of the test section, shadowgraphy was applied to visualize density gradient distribution. The behavior of the density wave in the channel is visualized and examined through the variation of the heat transfer coefficient. (author)

  8. Orbital forcing of climate 1.4 billion years ago

    DEFF Research Database (Denmark)

    Zhang, Shuichang; Wang, Xiaomei; Hammarlund, Emma U

    2015-01-01

    Fluctuating climate is a hallmark of Earth. As one transcends deep into Earth time, however, both the evidence for and the causes of climate change become difficult to establish. We report geochemical and sedimentological evidence for repeated, short-term climate fluctuations from the exceptionally...... well-preserved ∼1.4-billion-year-old Xiamaling Formation of the North China Craton. We observe two patterns of climate fluctuations: On long time scales, over what amounts to tens of millions of years, sediments of the Xiamaling Formation record changes in geochemistry consistent with long-term changes...... reflect what appear to be orbitally forced changes in wind patterns and ocean circulation as they influenced rates of organic carbon flux, trace metal accumulation, and the source of detrital particles to the sediment....

  9. Reconciliation of the Devils Hole climate record with orbital forcing.

    Science.gov (United States)

    Moseley, Gina E; Edwards, R Lawrence; Wendt, Kathleen A; Cheng, Hai; Dublyansky, Yuri; Lu, Yanbin; Boch, Ronny; Spötl, Christoph

    2016-01-08

    The driving force behind Quaternary glacial-interglacial cycles and much associated climate change is widely considered to be orbital forcing. However, previous versions of the iconic Devils Hole (Nevada) subaqueous calcite record exhibit shifts to interglacial values ~10,000 years before orbitally forced ice age terminations, and interglacial durations ~10,000 years longer than other estimates. Our measurements from Devils Hole 2 replicate virtually all aspects of the past 204,000 years of earlier records, except for the timing during terminations, and they lower the age of the record near Termination II by ~8000 years, removing both ~10,000-year anomalies. The shift to interglacial values now broadly coincides with the rise in boreal summer insolation, the marine termination, and the rise in atmospheric CO2, which is consistent with mechanisms ultimately tied to orbital forcing. Copyright © 2016, American Association for the Advancement of Science.

  10. Orbital Forcing driving climate variability on Tropical South Atlantic

    Science.gov (United States)

    Oliveira, A. S.; Baker, P. A.; Silva, C. G.; Dwyer, G. S.; Chiessi, C. M.; Rigsby, C. A.; Ferreira, F.

    2017-12-01

    Past research on climate response to orbital forcing in tropical South America has emphasized on high precession cycles influencing low latitude hydrologic cycles, and driving the meridional migration of Intertropical Convergence Zone (ITCZ).However, marine proxy records from the tropical Pacific Ocean showed a strong 41-ka periodicities in Pleistocene seawater temperature and productivity related to fluctuations in Earth's obliquity. It Indicates that the western Pacific ITCZ migration was influenced by combined precession and obliquity changes. To reconstruct different climate regimes over the continent and understand the orbital cycle forcing over Tropical South America climate, hydrological reconstruction have been undertaken on sediment cores located on the Brazilian continental slope, representing the past 1.6 million years. Core CDH 79 site is located on a 2345 m deep seamount on the northern Brazilian continental slope (00° 39.6853' N, 44° 20.7723' W), 320 km from modern coastline of the Maranhão Gulf. High-resolution XRF analyses of Fe, Ti, K and Ca are used to define the changes in precipitation and sedimentary input history of Tropical South America. The response of the hydrology cycle to orbital forcing was studied using spectral analysis.The 1600 ka records of dry/wet conditions presented here indicates that orbital time-scale climate change has been a dominant feature of tropical climate. We conclude that the observed oscillation reflects variability in the ITCZ activity associated with the Earth's tilt. The prevalence of the eccentricity and obliquity signals in continental hydrology proxies (Ti/Ca and Fe/K) as implicated in our precipitation records, highlights that these orbital forcings play an important role in tropics hydrologic cycles. Throughout the Quaternary abrupt shifts of tropical variability are temporally correlated with abrupt climate changes and atmospheric reorganization during Mid-Pleistocene Transition and Mid-Brunhes Events

  11. Regional aerosol emissions and temperature response: Local and remote climate impacts of regional aerosol forcing

    Science.gov (United States)

    Lewinschal, Anna; Ekman, Annica; Hansson, Hans-Christen

    2017-04-01

    Emissions of anthropogenic aerosols vary substantially over the globe and the short atmospheric residence time of aerosols leads to a highly uneven radiative forcing distribution, both spatially and temporally. Regional aerosol radiative forcing can, nevertheless, exert a large influence on the temperature field away from the forcing region through changes in heat transport or the atmospheric or ocean circulation. Moreover, the global temperature response distribution to aerosol forcing may vary depending on the geographical location of the forcing. In other words, the climate sensitivity in one region can vary depending on the location of the forcing. The surface temperature distribution response to changes in sulphate aerosol forcing caused by sulphur dioxide (SO2) emission perturbations in four different regions is investigated using the Norwegian Earth System Model (NorESM). The four regions, Europe, North America, East and South Asia, are all regions with historically high aerosol emissions and are relevant from both an air-quality and climate policy perspective. All emission perturbations are defined relative to the year 2000 emissions provided for the Coupled Model Intercomparison Project phase 5. The global mean temperature change per unit SO2 emission change is similar for all four regions for similar magnitudes of emissions changes. However, the global temperature change per unit SO2 emission in simulations where regional SO2 emission were removed is substantially higher than that obtained in simulations where regional SO2 emissions were increased. Thus, the climate sensitivity to regional SO2 emissions perturbations depends on the magnitude of the emission perturbation in NorESM. On regional scale, on the other hand, the emission perturbations in different geographical locations lead to different regional temperature responses, both locally and in remote regions. The results from the model simulations are used to construct regional temperature potential

  12. CLIMATE CHANGE. Long-term climate forcing by atmospheric oxygen concentrations.

    Science.gov (United States)

    Poulsen, Christopher J; Tabor, Clay; White, Joseph D

    2015-06-12

    The percentage of oxygen in Earth's atmosphere varied between 10% and 35% throughout the Phanerozoic. These changes have been linked to the evolution, radiation, and size of animals but have not been considered to affect climate. We conducted simulations showing that modulation of the partial pressure of oxygen (pO2), as a result of its contribution to atmospheric mass and density, influences the optical depth of the atmosphere. Under low pO2 and a reduced-density atmosphere, shortwave scattering by air molecules and clouds is less frequent, leading to a substantial increase in surface shortwave forcing. Through feedbacks involving latent heat fluxes to the atmosphere and marine stratus clouds, surface shortwave forcing drives increases in atmospheric water vapor and global precipitation, enhances greenhouse forcing, and raises global surface temperature. Our results implicate pO2 as an important factor in climate forcing throughout geologic time. Copyright © 2015, American Association for the Advancement of Science.

  13. Climate forcing and desert malaria: the effect of irrigation.

    Science.gov (United States)

    Baeza, Andres; Bouma, Menno J; Dobson, Andy P; Dhiman, Ramesh; Srivastava, Harish C; Pascual, Mercedes

    2011-07-14

    Rainfall variability and associated remote sensing indices for vegetation are central to the development of early warning systems for epidemic malaria in arid regions. The considerable change in land-use practices resulting from increasing irrigation in recent decades raises important questions on concomitant change in malaria dynamics and its coupling to climate forcing. Here, the consequences of irrigation level for malaria epidemics are addressed with extensive time series data for confirmed Plasmodium falciparum monthly cases, spanning over two decades for five districts in north-west India. The work specifically focuses on the response of malaria epidemics to rainfall forcing and how this response is affected by increasing irrigation. Remote sensing data for the Normalized Difference Vegetation Index (NDVI) are used as an integrated measure of rainfall to examine correlation maps within the districts and at regional scales. The analyses specifically address whether irrigation has decreased the coupling between malaria incidence and climate variability, and whether this reflects (1) a breakdown of NDVI as a useful indicator of risk, (2) a weakening of rainfall forcing and a concomitant decrease in epidemic risk, or (3) an increase in the control of malaria transmission. The predictive power of NDVI is compared against that of rainfall, using simple linear models and wavelet analysis to study the association of NDVI and malaria variability in the time and in the frequency domain respectively. The results show that irrigation dampens the influence of climate forcing on the magnitude and frequency of malaria epidemics and, therefore, reduces their predictability. At low irrigation levels, this decoupling reflects a breakdown of local but not regional NDVI as an indicator of rainfall forcing. At higher levels of irrigation, the weakened role of climate variability may be compounded by increased levels of control; nevertheless this leads to no significant decrease

  14. Radiative forcing in the ACCMIP historical and future climate simulations

    Directory of Open Access Journals (Sweden)

    D. T. Shindell

    2013-03-01

    Full Text Available The Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP examined the short-lived drivers of climate change in current climate models. Here we evaluate the 10 ACCMIP models that included aerosols, 8 of which also participated in the Coupled Model Intercomparison Project phase 5 (CMIP5. The models reproduce present-day total aerosol optical depth (AOD relatively well, though many are biased low. Contributions from individual aerosol components are quite different, however, and most models underestimate east Asian AOD. The models capture most 1980–2000 AOD trends well, but underpredict increases over the Yellow/Eastern Sea. They strongly underestimate absorbing AOD in many regions. We examine both the direct radiative forcing (RF and the forcing including rapid adjustments (effective radiative forcing; ERF, including direct and indirect effects. The models' all-sky 1850 to 2000 global mean annual average total aerosol RF is (mean; range −0.26 W m−2; −0.06 to −0.49 W m−2. Screening based on model skill in capturing observed AOD yields a best estimate of −0.42 W m−2; −0.33 to −0.50 W m−2, including adjustment for missing aerosol components in some models. Many ACCMIP and CMIP5 models appear to produce substantially smaller aerosol RF than this best estimate. Climate feedbacks contribute substantially (35 to −58% to modeled historical aerosol RF. The 1850 to 2000 aerosol ERF is −1.17 W m−2; −0.71 to −1.44 W m−2. Thus adjustments, including clouds, typically cause greater forcing than direct RF. Despite this, the multi-model spread relative to the mean is typically the same for ERF as it is for RF, or even smaller, over areas with substantial forcing. The largest 1850 to 2000 negative aerosol RF and ERF values are over and near Europe, south and east Asia and North America. ERF, however, is positive over the Sahara, the Karakoram, high Southern latitudes and especially the Arctic. Global aerosol RF

  15. Radiative forcing in the ACCMIP historical and future climate simulations

    Energy Technology Data Exchange (ETDEWEB)

    Shindell, D. T.; Lamarque, J. -F.; Schulz, M.; Flanner, M.; Jiao, C.; Chin, M.; Young, P. J.; Lee, Y. H.; Rotstayn, L.; Mahowald, N.; Milly, G.; Faluvegi, G.; Balkanski, Y.; Collins, W. J.; Conley, A. J.; Dalsoren, S.; Easter, R.; Ghan, S.; Horowitz, L.; Liu, X.; Myhre, G.; Nagashima, T.; Naik, V.; Rumbold, S. T.; Skeie, R.; Sudo, K.; Szopa, S.; Takemura, T.; Voulgarakis, A.; Yoon, J. -H.; Lo, F.

    2013-01-01

    The Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP) examined the short-lived drivers of climate change in current climate models. Here we evaluate the 10 ACCMIP models that included aerosols, 8 of which also participated in the Coupled Model Intercomparison Project phase 5 (CMIP5). The models reproduce present-day total aerosol optical depth (AOD) relatively well, though many are biased low. Contributions from individual aerosol components are quite different, however, and most models underestimate east Asian AOD. The models capture most 1980-2000 AOD trends well, but underpredict increases over the Yellow/Eastern Sea. They strongly underestimate absorbing AOD in many regions. We examine both the direct radiative forcing (RF) and the forcing including rapid adjustments (effective radiative forcing; ERF, including direct and indirect effects). The models’ all-sky 1850 to 2000 global mean annual average total aerosol RF is (mean; range) -0.26Wm-2-2. Screening based on model skill in capturing observed AOD yields a best estimate of -0.42Wm-2-2Climate feedbacks contribute substantially (35 to -58 %) to modeled historical aerosol RF. The 1850 to 2000 aerosol ERF is -1.17Wm-2-2forcing than direct RF. Despite this, the multi-model spread relative to the mean is typically the same for ERF as it is for RF, or even smaller, over areas with substantial forcing. The largest 1850 to 2000 negative aerosol RF and ERF values are over and near Europe, south and east Asia and North America. ERF, however, is positive over the Sahara, the Karakoram, high Southern latitudes and especially the Arctic. Global

  16. Radiative Forcing in the ACCMIP Historical and Future Climate Simulations

    Science.gov (United States)

    Shindell, Drew Todd; Lamarque, J.-F.; Schulz, M.; Flanner, M.; Jiao, C.; Chin, M.; Young, P. J.; Lee, Y. H.; Rotstayn, L.; Mahowald, N.; hide

    2013-01-01

    A primary goal of the Atmospheric Chemistry and Climate Model IntercomparisonProject (ACCMIP) was to characterize the short-lived drivers of preindustrial to 2100climate change in the current generation of climate models. Here we evaluate historicaland 5 future radiative forcing in the 10 ACCMIP models that included aerosols, 8 of whichalso participated in the Coupled Model Intercomparison Project phase 5 (CMIP5).The models generally reproduce present-day climatological total aerosol opticaldepth (AOD) relatively well. components to this total, however, and most appear to underestimate AOD over East10 Asia. The models generally capture 1980-2000 AOD trends fairly well, though theyunderpredict AOD increases over the YellowEastern Sea. They appear to strongly underestimate absorbing AOD, especially in East Asia, South and Southeast Asia, SouthAmerica and Southern Hemisphere Africa.We examined both the conventional direct radiative forcing at the tropopause (RF) and the forcing including rapid adjustments (adjusted forcing AF, including direct andindirect effects). The models calculated all aerosol all-sky 1850 to 2000 global meanannual average RF ranges from 0.06 to 0.49 W m(sup -2), with a mean of 0.26 W m(sup -2) and a median of 0.27 W m(sup -2. Adjusting for missing aerosol components in some modelsbrings the range to 0.12 to 0.62W m(sup -2), with a mean of 0.39W m(sup -2). Screen20ing the models based on their ability to capture spatial patterns and magnitudes ofAOD and AOD trends yields a quality-controlled mean of 0.42W m(sup -2) and range of0.33 to 0.50 W m(sup -2) (accounting for missing components). The CMIP5 subset of ACCMIPmodels spans 0.06 to 0.49W m(sup -2), suggesting some CMIP5 simulations likelyhave too little aerosol RF. A substantial, but not well quantified, contribution to histori25cal aerosol RF may come from climate feedbacks (35 to 58). The mean aerosol AF during this period is 1.12W m(sup -2) (median value 1.16W m(sup -2), range 0.72 to1.44W m

  17. Forcing of Climate Variations by Mev-gev Particles

    Science.gov (United States)

    Tinsley, Brian A.

    1990-01-01

    Changes in ionization production in the lower stratosphere by a few percent during Forbush decreases have been shown to correlate well with changes in winter tropospheric dynamics by a similar relatively small amount. Changes in ionization production by tens of percent on the decadal time scale have been shown to be correlated with changes in winter storm frequencies by tens of percent in the western North Atlantic. Changes in total solar irradiance or solar UV do not have time variations to match the tropospheric variations on the day to day time scales discussed here. Forcing related to magnetic activity is not supported. Thus solar wind/MeV-GeV particle changes appear to be the only viable forcing function for these day to day variations. If solar wind/particle forcing of a few percent amplitude can produce short term weather responses, then observed changes by tens of percent on the decadal and centennial time scale could produce climate changes on these longer time scales. The changes in circulation involved would produce regional climate changes, as observed. At present the relations between stratospheric ionization, electric fields and chemistry and aerosol and cloud microphysics are as poorly known as the relations between the latter and storm feedback processes. However, the capability for investigating these relationships now exists and has recently been most successfully used for elucidating the stratospheric chemistry and cloud microphysics associated with the Antarctic ozone hole. The economic benefits of being able to predict winter severity on an interannual basis, and the extent to which climate change related to solar variability will add to or substract from the greenhouse effect, should be more than adequate to justify support for research in this area.

  18. On the climate impacts from the volcanic and solar forcings

    Science.gov (United States)

    Varotsos, Costas A.; Lovejoy, Shaun

    2016-04-01

    The observed and the modelled estimations show that the main forcings on the atmosphere are of volcanic and solar origins, which act however in an opposite way. The former can be very strong and decrease at short time scales, whereas, the latter increase with time scale. On the contrary, the observed fluctuations in temperatures increase at long scales (e.g. centennial and millennial), and the solar forcings do increase with scale. The common practice is to reduce forcings to radiative equivalents assuming that their combination is linear. In order to clarify the validity of the linearity assumption and determine its range of validity, we systematically compare the statistical properties of solar only, volcanic only and combined solar and volcanic forcings over the range of time scales from one to 1000 years. Additionally, we attempt to investigate plausible reasons for the discrepancies observed between the measured and modeled anomalies of tropospheric temperatures in the tropics. For this purpose, we analyse tropospheric temperature anomalies for both the measured and modeled time series. The results obtained show that the measured temperature fluctuations reveal white noise behavior, while the modeled ones exhibit long-range power law correlations. We suggest that the persistent signal, should be removed from the modeled values in order to achieve better agreement with observations. Keywords: Scaling, Nonlinear variability, Climate system, Solar radiation

  19. Landscape dynamics and different climate forcings in eastern Mongolia

    Science.gov (United States)

    Moore, N. J.; John, R.; Chen, J.

    2017-12-01

    Central and Eastern Mongolia have witnessed significant decreasing greening from the period 2000-2012. This decline may be partially, directly due to increased grazing pressure from livestock. Our study objective is to understand how landscape change may be altering heat fluxes and precipitation. Using the RAMS 6.0 regional climate model, we simulated the spatiotemporal changes in growing-season precipitation and atmospheric behavior under: (a) observed vegetation, and (b) aggressively reduced vegetation, to prognose likely locations and changes of the regional climate that might have resulted from land cover changes (2001-2010). We simulated a dzud/drought year (using forcing from 2001) and a wet year (using forcing from 2003). Our simulations show increased cloud cover and reduced daily temperature ranges for northeastern Mongolia where forest growth has expanded. Localized differences of 60 W/m2 of sensible heat flux were found when degraded landscape cover replaced older, more dense cover. More importantly, the overall trend towards reduced vegetation cover was responsible for higher screen height temperatures and reduced soil moisture throughout much of the domain, together with a shift of moisture southward of Inner Mongolia. Thus, even with improved chances for convection, soil moisture reductions of 5-10% would lead to overall even drier conditions. In the steppe regions around the Gobi desert, more complex patterns are evident and landscape drivers are less clear.

  20. Direct and indirect climate change effects on carbon dioxide fluxes in a thawing boreal forest-wetland landscape.

    Science.gov (United States)

    Helbig, Manuel; Chasmer, Laura E; Desai, Ankur R; Kljun, Natascha; Quinton, William L; Sonnentag, Oliver

    2017-08-01

    In the sporadic permafrost zone of northwestern Canada, boreal forest carbon dioxide (CO 2 ) fluxes will be altered directly by climate change through changing meteorological forcing and indirectly through changes in landscape functioning associated with thaw-induced collapse-scar bog ('wetland') expansion. However, their combined effect on landscape-scale net ecosystem CO 2 exchange (NEE LAND ), resulting from changing gross primary productivity (GPP) and ecosystem respiration (ER), remains unknown. Here, we quantify indirect land cover change impacts on NEE LAND and direct climate change impacts on modeled temperature- and light-limited NEE LAND of a boreal forest-wetland landscape. Using nested eddy covariance flux towers, we find both GPP and ER to be larger at the landscape compared to the wetland level. However, annual NEE LAND (-20 g C m -2 ) and wetland NEE (-24 g C m -2 ) were similar, suggesting negligible wetland expansion effects on NEE LAND . In contrast, we find non-negligible direct climate change impacts when modeling NEE LAND using projected air temperature and incoming shortwave radiation. At the end of the 21st century, modeled GPP mainly increases in spring and fall due to reduced temperature limitation, but becomes more frequently light-limited in fall. In a warmer climate, ER increases year-round in the absence of moisture stress resulting in net CO 2 uptake increases in the shoulder seasons and decreases during the summer. Annually, landscape net CO 2 uptake is projected to decline by 25 ± 14 g C m -2 for a moderate and 103 ± 38 g C m -2 for a high warming scenario, potentially reversing recently observed positive net CO 2 uptake trends across the boreal biome. Thus, even without moisture stress, net CO 2 uptake of boreal forest-wetland landscapes may decline, and ultimately, these landscapes may turn into net CO 2 sources under continued anthropogenic CO 2 emissions. We conclude that NEE LAND changes are more likely to be

  1. Satellite methods underestimate indirect climate forcing by aerosols

    Science.gov (United States)

    Penner, Joyce E.; Xu, Li; Wang, Minghuai

    2011-01-01

    Satellite-based estimates of the aerosol indirect effect (AIE) are consistently smaller than the estimates from global aerosol models, and, partly as a result of these differences, the assessment of this climate forcing includes large uncertainties. Satellite estimates typically use the present-day (PD) relationship between observed cloud drop number concentrations (Nc) and aerosol optical depths (AODs) to determine the preindustrial (PI) values of Nc. These values are then used to determine the PD and PI cloud albedos and, thus, the effect of anthropogenic aerosols on top of the atmosphere radiative fluxes. Here, we use a model with realistic aerosol and cloud processes to show that empirical relationships for ln(Nc) versus ln(AOD) derived from PD results do not represent the atmospheric perturbation caused by the addition of anthropogenic aerosols to the preindustrial atmosphere. As a result, the model estimates based on satellite methods of the AIE are between a factor of 3 to more than a factor of 6 smaller than model estimates based on actual PD and PI values for Nc. Using ln(Nc) versus ln(AI) (Aerosol Index, or the optical depth times angstrom exponent) to estimate preindustrial values for Nc provides estimates for Nc and forcing that are closer to the values predicted by the model. Nevertheless, the AIE using ln(Nc) versus ln(AI) may be substantially incorrect on a regional basis and may underestimate or overestimate the global average forcing by 25 to 35%. PMID:21808047

  2. Energy supplies in view of the climatic problem with carbon dioxide

    International Nuclear Information System (INIS)

    Voigt, H.

    1988-01-01

    Climatic changes can be expected with increasing and even with stagnating carbon dioxide emissions. If they are to be restricted to an apparently bearable level, the consumption of fossil energy carriers must be reduced. This can be attained through a reduction in requirement and through increased use of non-fossil primary energy forms. Amongst these, nuclear energy and hydroelectricity are already available. Both nuclear energy and solar energy are by human standards adequate and inexhaustible sources of energy, if thorium 232 and uranium 238 are used in high temperature and breeder reactors and if the new techniques for the extensive use of solar energy are successfully developed. A possible structure for the future energy supply industry with a third of present-day carbon dioxide emissions is presented for the example of the Federal Republic of Germany and for a global model. The change in structure must begin now, because later the rates of change needed would be unrealistically high from a technical and economic point of view. Some apparently necessary and possible steps towards this objective are indicated. (orig.) [de

  3. The radiative forcing potential of different climate geoengineering options

    Directory of Open Access Journals (Sweden)

    T. M. Lenton

    2009-08-01

    Full Text Available Climate geoengineering proposals seek to rectify the Earth's current and potential future radiative imbalance, either by reducing the absorption of incoming solar (shortwave radiation, or by removing CO2 from the atmosphere and transferring it to long-lived reservoirs, thus increasing outgoing longwave radiation. A fundamental criterion for evaluating geoengineering options is their climate cooling effectiveness, which we quantify here in terms of radiative forcing potential. We use a simple analytical approach, based on energy balance considerations and pulse response functions for the decay of CO2 perturbations. This aids transparency compared to calculations with complex numerical models, but is not intended to be definitive. It allows us to compare the relative effectiveness of a range of proposals. We consider geoengineering options as additional to large reductions in CO2 emissions. By 2050, some land carbon cycle geoengineering options could be of comparable magnitude to mitigation "wedges", but only stratospheric aerosol injections, albedo enhancement of marine stratocumulus clouds, or sunshades in space have the potential to cool the climate back toward its pre-industrial state. Strong mitigation, combined with global-scale air capture and storage, afforestation, and bio-char production, i.e. enhanced CO2 sinks, might be able to bring CO2 back to its pre-industrial level by 2100, thus removing the need for other geoengineering. Alternatively, strong mitigation stabilising CO2 at 500 ppm, combined with geoengineered increases in the albedo of marine stratiform clouds, grasslands, croplands and human settlements might achieve a patchy cancellation of radiative forcing. Ocean fertilisation options are only worthwhile if sustained on a millennial timescale and phosphorus addition may have greater long-term potential than iron or nitrogen fertilisation. Enhancing ocean

  4. Impact of preindustrial to present-day changes in short-lived pollutant emissions on atmospheric composition and climate forcing

    Science.gov (United States)

    Naik, Vaishali; Horowitz, Larry W.; Fiore, Arlene M.; Ginoux, Paul; Mao, Jingqiu; Aghedo, Adetutu M.; Levy, Hiram

    2013-07-01

    We describe and evaluate atmospheric chemistry in the newly developed Geophysical Fluid Dynamics Laboratory chemistry-climate model (GFDL AM3) and apply it to investigate the net impact of preindustrial (PI) to present (PD) changes in short-lived pollutant emissions (ozone precursors, sulfur dioxide, and carbonaceous aerosols) and methane concentration on atmospheric composition and climate forcing. The inclusion of online troposphere-stratosphere interactions, gas-aerosol chemistry, and aerosol-cloud interactions (including direct and indirect aerosol radiative effects) in AM3 enables a more complete representation of interactions among short-lived species, and thus their net climate impact, than was considered in previous climate assessments. The base AM3 simulation, driven with observed sea surface temperature (SST) and sea ice cover (SIC) over the period 1981-2007, generally reproduces the observed mean magnitude, spatial distribution, and seasonal cycle of tropospheric ozone and carbon monoxide. The global mean aerosol optical depth in our base simulation is within 5% of satellite measurements over the 1982-2006 time period. We conduct a pair of simulations in which only the short-lived pollutant emissions and methane concentrations are changed from PI (1860) to PD (2000) levels (i.e., SST, SIC, greenhouse gases, and ozone-depleting substances are held at PD levels). From the PI to PD, we find that changes in short-lived pollutant emissions and methane have caused the tropospheric ozone burden to increase by 39% and the global burdens of sulfate, black carbon, and organic carbon to increase by factors of 3, 2.4, and 1.4, respectively. Tropospheric hydroxyl concentration decreases by 7%, showing that increases in OH sinks (methane, carbon monoxide, nonmethane volatile organic compounds, and sulfur dioxide) dominate over sources (ozone and nitrogen oxides) in the model. Combined changes in tropospheric ozone and aerosols cause a net negative top

  5. The role of orbital forcing, carbon dioxide and regolith in 100 kyr glacial cycles

    Directory of Open Access Journals (Sweden)

    A. Ganopolski

    2011-12-01

    Full Text Available The origin of the 100 kyr cyclicity, which dominates ice volume variations and other climate records over the past million years, remains debatable. Here, using a comprehensive Earth system model of intermediate complexity, we demonstrate that both strong 100 kyr periodicity in the ice volume variations and the timing of glacial terminations during past 800 kyr can be successfully simulated as direct, strongly nonlinear responses of the climate-cryosphere system to orbital forcing alone, if the atmospheric CO2 concentration stays below its typical interglacial value. The existence of long glacial cycles is primarily attributed to the North American ice sheet and requires the presence of a large continental area with exposed rocks. We show that the sharp, 100 kyr peak in the power spectrum of ice volume results from the long glacial cycles being synchronized with the Earth's orbital eccentricity. Although 100 kyr cyclicity can be simulated with a constant CO2 concentration, temporal variability in the CO2 concentration plays an important role in the amplification of the 100 kyr cycles.

  6. Climate change forces new ecological states in tropical Andean lakes.

    Directory of Open Access Journals (Sweden)

    Neal Michelutti

    Full Text Available Air temperatures in the tropical Andes have risen at an accelerated rate relative to the global average over recent decades. However, the effects of climate change on Andean lakes, which are vital to sustaining regional biodiversity and serve as an important water resource to local populations, remain largely unknown. Here, we show that recent climate changes have forced alpine lakes of the equatorial Andes towards new ecological and physical states, in close synchrony to the rapid shrinkage of glaciers regionally. Using dated sediment cores from three lakes in the southern Sierra of Ecuador, we record abrupt increases in the planktonic thalassiosiroid diatom Discostella stelligera from trace abundances to dominance within the phytoplankton. This unprecedented shift occurs against the backdrop of rising temperatures, changing atmospheric pressure fields, and declining wind speeds. Ecological restructuring in these lakes is linked to warming and/or enhanced water column stratification. In contrast to seasonally ice-covered Arctic and temperate alpine counterparts, aquatic production has not increased universally with warming, and has even declined in some lakes, possibly because enhanced thermal stability impedes the re-circulation of hypolimnetic nutrients to surface waters. Our results demonstrate that these lakes have already passed important ecological thresholds, with potentially far-reaching consequences for Andean water resources.

  7. Experimental evidence of reorganizing landscape under changing climatic forcing

    Science.gov (United States)

    Singh, A.; Tejedor, A.; Zaliapin, I. V.; Reinhardt, L.; Foufoula-Georgiou, E.

    2015-12-01

    Quantification of the dynamics of landscape reorganization under changing climatic forcing is important to understand geomorphic transport laws under transient conditions, assess response of landscapes to external perturbations for future predictive modeling, and for interpreting past climate from stratigraphic record. For such an analysis, however, real landscape observations are limited. To this end, a series of controlled laboratory experiments on evolving landscape were conducted at the St. Anthony Falls laboratory at the University of Minnesota. High resolution elevation data at a temporal resolution of 5 mins and spatial resolution of 0.5 mm were collected as the landscape approached steady state (constant uplift and precipitation rate) and in the transient state (under the same uplift and 5 times precipitation rate). Our results reveal rapid topographic re-organization under a five-fold increase in precipitation with the fluvial regime encroaching into the previously debris dominated regime, widening and aggradation of channels and valleys, and accelerated erosion happening at hillslope scales. To better understand the initiation of the observed reorganization, we perform a connectivity and clustering analysis of the erosional and depositional events, showing strikingly different spatial patterns on landscape evolution under steady-state (SS) and transient-state (TS), even when the time under SS is renormalized to match the total volume of eroded and deposited sediment in TS. Our results suggest a regime shift in the behavior of transport processes on the landscape at the intermediate scales i.e., from supply-limited to transport-limited.

  8. Non-Kyoto radiative forcing in long-run greenhouse gas emissions and climate change scenarios

    NARCIS (Netherlands)

    Rose, S.K.; Kriegler, E.; Bibas, R.; Calvin, K.; Popp, A.; van Vuuren, D.P.|info:eu-repo/dai/nl/11522016X; Weyant, J.

    2014-01-01

    Climate policies must consider radiative forcing from Kyoto greenhouse gases, as well as other forcing constituents, such as aerosols and tropospheric ozone that result from air pollutants. Non-Kyoto forcing constituents contribute negative, as well as positive forcing, and overall increases in

  9. Carbon dioxide emissions and climate change: policy implications for the cement industry

    International Nuclear Information System (INIS)

    Rehan, R.; Nehdi, M.

    2005-01-01

    There is growing awareness that the cement industry is a significant contributor to global carbon dioxide (CO 2 ) emissions. It is expected that this industry will come under increasing regulatory pressures to reduce its emissions and contribute more aggressively to mitigating global warming. It is important that the industry's stakeholders become more familiar with greenhouse gas (GHG) emission and associated global warming issues, along with emerging policies that may affect the future of the industry. This paper discusses climate change, the current and proposed actions for mitigating its effects, and the implications of such actions for the cement industry. International negotiations on climate change are summarized and mechanisms available under the Kyoto Protocol for reducing greenhouse gas emissions are explained. The paper examines some of the traditional and emerging policy instruments for greenhouse gas emissions and analyses their merits and drawbacks. The applicability, effectiveness and potential impact of these policy instruments for the global cement industry in general and the Canadian cement industry in particular are discussed with recommendations for possible courses of action

  10. Orbital forcing of Arctic climate: mechanisms of climate response and implications for continental glaciation

    Energy Technology Data Exchange (ETDEWEB)

    Jackson, C S [Program in Atmospheric and Oceanic Sciences, Princeton University, NJ 08542, Princeton (United States); Institute for Geophysics, The John A. and Katherine G. Jackson School of Geosciences, The University of Texas at Austin, 4412 Spicewood Springs Rd., Bldg 600, TX 78759, Austin (United States); Broccoli, A J [NOAA/Geophysical Fluid Dynamics Laboratory, NJ 08542, Princeton (United States); Department of Environmental Sciences, Rutgers University, NJ 08903, New Brunswick (United States)

    2003-12-01

    Progress in understanding how terrestrial ice volume is linked to Earth's orbital configuration has been impeded by the cost of simulating climate system processes relevant to glaciation over orbital time scales (10{sup 3}-10{sup 5} years). A compromise is usually made to represent the climate system by models that are averaged over one or more spatial dimensions or by three-dimensional models that are limited to simulating particular ''snapshots'' in time. We take advantage of the short equilibration time ({proportional_to}10 years) of a climate model consisting of a three-dimensional atmosphere coupled to a simple slab ocean to derive the equilibrium climate response to accelerated variations in Earth's orbital configuration over the past 165,000 years. Prominent decreases in ice melt and increases in snowfall are simulated during three time intervals near 26, 73, and 117 thousand years ago (ka) when aphelion was in late spring and obliquity was low. There were also significant decreases in ice melt and increases in snowfall near 97 and 142 ka when eccentricity was relatively large, aphelion was in late spring, and obliquity was high or near its long term mean. These ''glaciation-friendly'' time intervals correspond to prominent and secondary phases of terrestrial ice growth seen within the marine {delta}{sup 18}O record. Both dynamical and thermal effects contribute to the increases in snowfall during these periods, through increases in storm activity and the fraction of precipitation falling as snow. The majority of the mid- to high latitude response to orbital forcing is organized by the properties of sea ice, through its influence on radiative feedbacks that nearly double the size of the orbital forcing as well as its influence on the seasonal evolution of the latitudinal temperature gradient. (orig.)

  11. Untangling Topographic and Climatic Forcing of Earthflow Motion

    Science.gov (United States)

    Finnegan, N. J.; Nereson, A. L.

    2017-12-01

    . They also suggest that earthflow motion is more sensitive to pore-fluid pressure forcing than to topographic forcing and challenge the view that attenuation of pore fluid pressure with depth renders large landslides relatively insensitive to high frequency climate variability.

  12. Retrofitting Forced Air Combi Systems: A Cold Climate Field Assessment

    Energy Technology Data Exchange (ETDEWEB)

    Schoenbauer, Ben [NorthernSTAR, St. Paul, MN (United States); Bohac, Dave [NorthernSTAR, St. Paul, MN (United States); McAlpine, Jack [NorthernSTAR, St. Paul, MN (United States); Hewett, Martha [NorthernSTAR, St. Paul, MN (United States)

    2017-06-01

    This project analyzed combined condensing water heaters or boilers and hydronic air coils to provide high efficiency domestic hot water (DHW) and forced air space heating. Called "combi" systems, they provided similar space and water heating performance less expensively than installing two condensing appliances. The system's installed costs were cheaper than installing a condensing furnace and either a condensing tankless or condensing storage water heater. However, combi costs must mature and be reduced before they are competitive with a condensing furnace and power vented water heater (energy factor of 0.60). Better insulation and tighter envelopes are reducing space heating loads for new and existing homes. For many homes, decreased space heating loads make it possible for both space and domestic water heating loads to be provided with a single heating plant. These systems can also eliminate safety issues associated with natural draft appliances through the use of one common sealed combustion vent. The combined space and water heating approach was not a new idea. Past systems have used non-condensing heating plants, which limited their usefulness in climates with high heating loads. Previous laboratory work (Schoenbauer et al. 2012a) showed that proper installation was necessary to achieve condensing with high efficiency appliances. Careful consideration was paid to proper system sizing and minimizing the water temperature returning from the air handling unit to facilitate condensing operation.

  13. Retrofitting Forced Air Combi Systems: A Cold Climate Field Assessment

    Energy Technology Data Exchange (ETDEWEB)

    Schoenbauer, Ben [Univ. of Minnesota, St. Paul, MN (United States). NorthernSTAR Building America Partnership; Bohac, Dave [Univ. of Minnesota, St. Paul, MN (United States). NorthernSTAR Building America Partnership; McAlpine, Jake [Univ. of Minnesota, St. Paul, MN (United States). NorthernSTAR Building America Partnership; Hewett, Martha [Univ. of Minnesota, St. Paul, MN (United States). NorthernSTAR Building America Partnership

    2017-06-23

    This project analyzed combined condensing water heaters or boilers and hydronic air coils to provide high efficiency domestic hot water (DHW) and forced air space heating. Called 'combi' systems, they provided similar space and water heating performance less expensively than installing two condensing appliances. The system's installed costs were cheaper than installing a condensing furnace and either a condensing tankless or condensing storage water heater. However, combi costs must mature and be reduced before they are competitive with a condensing furnace and power vented water heater (energy factor of 0.60). Better insulation and tighter envelopes are reducing space heating loads for new and existing homes. For many homes, decreased space heating loads make it possible for both space and domestic water heating loads to be provided with a single heating plant. These systems can also eliminate safety issues associated with natural draft appliances through the use of one common sealed combustion vent. The combined space and water heating approach was not a new idea. Past systems have used non-condensing heating plants, which limited their usefulness in climates with high heating loads. Previous laboratory work (Schoenbauer et al. 2012a) showed that proper installation was necessary to achieve condensing with high efficiency appliances. Careful consideration was paid to proper system sizing and minimizing the water temperature returning from the air handling unit to facilitate condensing operation.

  14. Long-term climate monitoring by the global climate observing system: report of breakout group 1 - climate forcings and feedbacks

    International Nuclear Information System (INIS)

    Miller, C.; Bretherton, F.

    1995-01-01

    The assignment for Breakout Group A was to re-visit and expand upon the plenary session discussion on climate forcings and feedbacks and to develop a set of recommendations for each of the science disciplines or activities covered within this breakout category. Working guidelines for the group included identifying: (1) what has to be done; (2) why it has to be done, i.e. who is the customer? (3) the process for remedying deficiencies and, specifically, how to leverage the activities at operational centers; and (4) priorities (recognizing that it is premature to distinguish between major systems). The science ares addressed included: greenhouse gases (GHGs); radiation budget; water vapor; aerosols; clouds; precipitation; tropospheric ozone; and solar radiation. The role of climate satellites was also noted

  15. Recent changes in carbon dioxide, carbon monoxide and methane and the implications for global climate change

    Energy Technology Data Exchange (ETDEWEB)

    Novelli, P.C.; Conway, T.J.; Dlugokencky, E.J.; Tans, P.P. [National Oceanic and Atmospheric Administration, Boulder, CO (United States). Climate Monitoring and Diagnostics Lab.

    1995-01-01

    The article reviews figures for published data on recent changes of atmospheric levels of carbon dioxide, carbon monoxide and methane in terms of their sources and sinks. The largest source of CO{sub 2} is the combustion of fossil fuels, followed by emissions from deforestation and the oxidation of CO to CO{sub 2}. Carbon monoxide has an indirect influence on the earth`s radiative balance, as if levels of CO increase, levels of OH radicals decline which affects removal of other gases oxidised by this radical, notably CH{sub 4}. Major sources of CO are fossil fuel combustion, emissions from biomass, and oxidation of atmospheric CH{sub 4} and other non-methane hydrocarbons. The latest measurements suggest the depressed growth rates of CO{sub 2}, CO and CH{sub 4} have began to recover. Reasons for this are suggested. Future monitoring of atmospheric species in laboratories around the world, coupled with information on the isotopic signature of the trace gases, will improve our understanding of possible causes for trends in these gases. This will be invaluable in making policy decisions regarding future climate change. 34 refs., 4 figs.

  16. Relative linkages of peatland methane and carbon dioxide fluxes with climatic, environmental and ecological parameters and their inter-comparison

    Science.gov (United States)

    Banerjee, Tirtha; Hommeltenberg, Janina; Roy, Avipsa; De Roo, Frederik; Mauder, Matthias

    2016-04-01

    Although methane (CH4) is the second most important greenhouse gas (GHG) after CO2, about 80% of its global production is biogenic (wetlands, enteric fermentation and water disposal from animals) contrary to major anthropogenic sources of most other GHGs. Although on a shorter time scale, global emissions of methane are greater (10 year time frame) or about 80% (20 year time frame) of those of carbon dioxide in terms of their influence on global warming, methane emissions have been studied much less than CO2 emissions. Lakes, reservoirs and wetlands are estimated to contribute about 15-40% to the global methane source budget, which is higher than total oceanic CH4 emission. Half of the world's wetlands are represented by peatlands which cover 3% of the global total land area. Peatlands have a thick water-logged organic soil layer (peat) made up of dead and decaying plant material. Moreover, they are carbon rich, containing twice as much stock as the entire forest biomass of the world (550 Gt carbon). When disturbed, they can become significant sources of greenhouse gas emissions. The organic carbon exposed to air due to various mechanisms can release CH4 or CO2 in the atmosphere. Thus the nature of vegetation cover, radiation environment, wind turbulence, soil characteristics, water table depth etc. are expected to be important forcings that influence the emission of CH4 or CO2 in the shorter time scale. However, long term climate change can also influence these governing factors themselves over a larger time scale, which in turn can influence the wetland GHG emissions. Thus developing a predictive framework and long term source appropriation for wetland CH4 or CO2 warrants an identification of the major environmental forcings on the CH4 or CO2 flux. In the present work, we use a simple and systematic data-analytics approach to determine the relative linkages of different climate and environmental variables with the canopy level half-hourly CH4 or CO2 fluxes over a

  17. Locking of Turing patterns in the chlorine dioxide-iodine-malonic acid reaction with one-dimensional spatial periodic forcing.

    Science.gov (United States)

    Dolnik, Milos; Bánsági, Tamás; Ansari, Sama; Valent, Ivan; Epstein, Irving R

    2011-07-21

    We use the photosensitive chlorine dioxide-iodine-malonic acid reaction-diffusion system to study wavenumber locking of Turing patterns with spatial periodic forcing. Wavenumber-locked stripe patterns are the typical resonant structures that labyrinthine patterns exhibit in response to one-dimensional forcing by illumination when images of stripes are projected on a working medium. Our experimental results reveal that segmented oblique, hexagonal and rectangular patterns can also be obtained. However, these two-dimensional resonant structures only develop in a relatively narrow range of forcing parameters, where the unforced stripe pattern is in close proximity to the domain of hexagonal patterns. Numerical simulations based on a model that incorporates the forcing by illumination using an additive term reproduce well the experimental observations. These findings confirm that additive one-dimensional forcing can generate a two-dimensional resonant response. However, such a response is considerably less robust than the effect of multiplicative forcing. This journal is © the Owner Societies 2011

  18. Testing For The Linearity of Responses To Multiple Anthropogenic Climate Forcings

    Science.gov (United States)

    Forest, C. E.; Stone, P. H.; Sokolov, A. P.

    To test whether climate forcings are additive, we compare climate model simulations in which anthropogenic forcings are applied individually and in combination. Tests are performed with different values for climate system properties (climate sensitivity and rate of heat uptake by the deep ocean) as well as for different strengths of the net aerosol forcing, thereby testing for the dependence of linearity on these properties. The MIT 2D Land-Ocean Climate Model used in this study consists of a zonally aver- aged statistical-dynamical atmospheric model coupled to a mixed-layer Q-flux ocean model, with heat anomalies diffused into the deep ocean. Following our previous stud- ies, the anthropogenic forcings are the changes in concentrations of greenhouse gases (1860-1995), sulfate aerosol (1860-1995), and stratospheric and tropospheric ozone (1979-1995). The sulfate aerosol forcing is applied as a surface albedo change. For an aerosol forcing of -1.0 W/m2 and an effective ocean diffusitivity of 2.5 cm2/s, the nonlinearity of the response of global-mean surface temperatures to the combined forcing shows a strong dependence on climate sensitivity. The fractional change in decadal averages ([(TG + TS + TO) - TGSO]/TGSO) for the 1986-1995 period compared to pre-industrial times are 0.43, 0.90, and 1.08 with climate sensitiv- ities of 3.0, 4.5, and 6.2 C, respectively. The values of TGSO for these three cases o are 0.52, 0.62, and 0.76 C. The dependence of linearity on climate system properties, o the role of climate system feedbacks, and the implications for the detection of climate system's response to individual forcings will be presented. Details of the model and forcings can be found at http://web.mit.edu/globalchange/www/.

  19. Response of carbon fluxes and climate to orbital forcing changes in the Community Climate System Model

    Science.gov (United States)

    Jochum, M.; Peacock, S.; Moore, J. K.; Lindsay, K. T.

    2009-12-01

    A global general circulation model coupled to an ocean ecosystem model is used to quantify the response of carbon fluxes and climate to changes in orbital forcing. Compared to the present-day simulation, the simulation with the Earth's orbital parameters from 115,000 years ago features significantly cooler northern high latitudes, but only moderately cooler southern high latitudes. This asymmetry is explained by a 30% reduction of the strength of the Atlantic Meridional Overturning Circulation that is caused by an increased Arctic sea-ice export and a resulting freshening of the North Atlantic. The strong northern high-latitude cooling and the direct insolation induced tropical warming lead to global shifts in precipitation and winds to the order of 10-20%. These climate shifts lead to regional differences in air-sea carbon fluxes of the same order. However, the differences in global net carbon fluxes are insignificant. This surprising result is due to several effects, two of which stand out: Firstly, colder sea surface temperature leads to a more effective solubility pump but also to increased sea-ice concentration which blocks air-sea exchange; and secondly, the weakening of Southern Ocean winds, which is predicted by some idealized studies, is small compared to its interannual variability.

  20. Potentials, consequences and trade-offs of terrestrial carbon dioxide removal. Strategies for climate engineering and their limitations

    Energy Technology Data Exchange (ETDEWEB)

    Boysen, Lena R.

    2017-01-17

    For hundreds of years, humans have engineered the planet to fulfil their need for increasing energy consumption and production. Since the industrial revolution, one consequence are rising global mean temperatures which could change by 2 C to 4.5 C until 2100 if mitigation enforcement of CO{sub 2} emissions fails.To counteract this projected global warming, climate engineering techniques aim at intendedly cooling Earth's climate for example through terrestrial carbon dioxide removal (tCDR) which is commonly perceived as environmentally friendly. Here, tCDR refers to the establishment of large-scale biomass plantations (BPs) in combination with the production of long-lasting carbon products such as bioenergy with carbon capture and storage or biochar. This thesis examines the potentials and possible consequences of tCDR by analysing land-use scenarios with different spatial and temporal scales of BPs using an advanced biosphere model forced by varying climate projections. These scenario simulations were evaluated with focus on their carbon sequestration potentials, trade-offs with food production and impacts on natural ecosystems and climate itself. Synthesised, the potential of tCDR to permanently extract CO{sub 2} out of the atmosphere is found to be small, regardless of the emission scenario, the point of onset or the spatial extent. On the contrary, the aforementioned trade-offs and impacts are shown to be unfavourable in most cases. In a high emission scenario with a late onset of BPs (i.e. around 2050), even unlimited area availability for tCDR could not reverse past emissions sufficiently, e.g. BPs covering 25% of all agricultural or natural land could delay 2100's carbon budget by no more than two or three decades (equivalent to ∼550 or 800 GtC tCDR), respectively. However, simultaneous emission reductions and an earlier establishment of BPs (i.e. around 2035) could result in strong carbon extractions reversing past emissions (e.g. six or eight

  1. Potentials, consequences and trade-offs of terrestrial carbon dioxide removal. Strategies for climate engineering and their limitations

    International Nuclear Information System (INIS)

    Boysen, Lena R.

    2017-01-01

    For hundreds of years, humans have engineered the planet to fulfil their need for increasing energy consumption and production. Since the industrial revolution, one consequence are rising global mean temperatures which could change by 2 C to 4.5 C until 2100 if mitigation enforcement of CO_2 emissions fails.To counteract this projected global warming, climate engineering techniques aim at intendedly cooling Earth's climate for example through terrestrial carbon dioxide removal (tCDR) which is commonly perceived as environmentally friendly. Here, tCDR refers to the establishment of large-scale biomass plantations (BPs) in combination with the production of long-lasting carbon products such as bioenergy with carbon capture and storage or biochar. This thesis examines the potentials and possible consequences of tCDR by analysing land-use scenarios with different spatial and temporal scales of BPs using an advanced biosphere model forced by varying climate projections. These scenario simulations were evaluated with focus on their carbon sequestration potentials, trade-offs with food production and impacts on natural ecosystems and climate itself. Synthesised, the potential of tCDR to permanently extract CO_2 out of the atmosphere is found to be small, regardless of the emission scenario, the point of onset or the spatial extent. On the contrary, the aforementioned trade-offs and impacts are shown to be unfavourable in most cases. In a high emission scenario with a late onset of BPs (i.e. around 2050), even unlimited area availability for tCDR could not reverse past emissions sufficiently, e.g. BPs covering 25% of all agricultural or natural land could delay 2100's carbon budget by no more than two or three decades (equivalent to ∼550 or 800 GtC tCDR), respectively. However, simultaneous emission reductions and an earlier establishment of BPs (i.e. around 2035) could result in strong carbon extractions reversing past emissions (e.g. six or eight decades or ∼500 or

  2. Global economic effects of changes in crops, pasture, and forests due to changing climate, carbon dioxide, and ozone

    International Nuclear Information System (INIS)

    Reilly, J.; Paltsev, S.; Felzer, B.; Wang, X.; Kicklighter, D.; Melillo, J.; Prinn, R.; Sarofim, M.; Sokolov, A.; Wang, C.

    2007-01-01

    Multiple environmental changes will have consequences for global vegetation. To the extent that crop yields and pasture and forest productivity are affected, there can be important economic consequences. We examine the combined effects of changes in climate, increases in carbon dioxide (CO 2 ), and changes in tropospheric ozone on crop, pasture, and forest lands and the consequences for the global and regional economies. We examine scenarios where there is limited or little effort to control these substances, and policy scenarios that limit emissions of CO 2 and ozone precursors. We find the effects of climate and CO 2 to be generally positive, and the effects of ozone to be very detrimental. Unless ozone is strongly controlled, damage could offset CO 2 and climate benefits. We find that resource allocation among sectors in the economy, and trade among countries, can strongly affect the estimate of economic effect in a country

  3. Linking the uncertainty of low frequency variability in tropical forcing in regional climate change

    Energy Technology Data Exchange (ETDEWEB)

    Forest, Chris E. [Pennsylvania State Univ., University Park, PA (United States). Dept. of Meteorology; Barsugli, Joseph J. [Univ. of Colorado, Boulder, CO (United States). CIRES; Li, Wei [Pennsylvania State Univ., University Park, PA (United States). Dept. of Meteorology

    2015-02-20

    The project utilizes multiple atmospheric general circulation models (AGCMs) to examine the regional climate sensitivity to tropical sea surface temperature forcing through a series of ensemble experiments. The overall goal for this work is to use the global teleconnection operator (GTO) as a metric to assess the impact of model structural differences on the uncertainties in regional climate variability.

  4. Specifics of forced-convective heat transfer in supercritical carbon dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Saltanov, A.E.; Mann, B.D.; Harvel, C.G.; Pioro, D.I., E-mail: Eugene.saltanov@hotmail.com [University of Ontario Institute of Technology, Oshawa, ON (Canada)

    2015-07-01

    The appropriate description of heat-transfer to coolants at supercritical state is one of the main challenges in development of supercritical-fluids applications for the Generation-IV reactors. In this paper the basis for comparison of relatively recent experimental data on supercritical carbon dioxide (CO{sub 2}) obtained at facilities of the Korea Atomic Energy Research Institute (KAERI) and Chalk River Laboratories (CRL) of Atomic Energy of Canada Limited (AECL) is discussed, and a preliminary heat-transfer correlation for joint CRL and KAERI datasets is presented. (author)

  5. Assessing the Organizational Climate in the Belgian Armed Forces

    National Research Council Canada - National Science Library

    Mylle, Jacques

    1998-01-01

    ... are. Organizational climate is defined as the synthetic, collective perception of a set of relatively stable internal aspects of the organization as experienced and described by the members of that organization.

  6. Carbon dioxide and climate. [Appendix includes names and addresses of the Principal Investigators for the research projects funded in FY1991

    Energy Technology Data Exchange (ETDEWEB)

    1991-10-01

    Global climate change is a serious environmental concern, and the US has developed An Action Agenda'' to deal with it. At the heart of the US effort is the US Global Change Research Program (USGCRP), which has been developed by the Committee on Earth and Environmental Sciences (CEES) of the Federal Coordinating Council for Sciences, Engineering, and Technology (FCCSET). The USGCRP will provide the scientific basis for sound policy making on the climate-change issue. The DOE contribution to the USGCRP is the Carbon Dioxide Research Program, which now places particular emphasis on the rapid improvement of the capability to predict global and regional climate change. DOE's Carbon Dioxide Research Program has been addressing the carbon dioxide-climate change connection for more than twelve years and has provided a solid scientific foundation for the USGCRP. The expansion of the DOE effort reflects the increased attention that the Department has placed on the issue and is reflected in the National Energy Strategy (NES) that was released in 1991. This Program Summary describes projects funded by the Carbon Dioxide Research Program during FY 1991 and gives a brief overview of objectives, organization, and accomplishments. The Environmental Sciences Division of the Office of Health and Environmental Research, Office of Energy Research supports a Carbon Dioxide Research Program to determine the scientific linkage between the rise of greenhouse gases in the atmosphere, especially carbon dioxide, and climate and vegetation change. One facet is the Core CO{sub 2} Program, a pioneering program that DOE established more than 10 years ago to understand and predict the ways that fossil-fuel burning could affect atmospheric CO{sub 2} concentration, global climate, and the Earth's biosphere. Major research areas are: global carbon cycle; climate detection and models of climate change; vegetation research; resource analysis; and, information and integration.

  7. Climate and carbon-cycle response to astronomical forcing over the last 35 Ma.

    Science.gov (United States)

    De Vleeschouwer, D.; Palike, H.; Vahlenkamp, M.; Crucifix, M.

    2017-12-01

    On a million-year time scale, the characteristics of insolation forcing caused by cyclical variations in the astronomical parameters of the Earth remain stable. Nevertheless, Earth's climate responded very differently to this forcing during different parts of the Cenozoic. The recently-published ∂18Obenthic megasplice (De Vleeschouwer et al., 2017) allowed for a clear visualization of these changes in global climate response to astronomical forcing. However, many open questions remain regarding how carbon-cycle dynamics influence Earth's climate sensitivity to astronomical climate forcing. To provide insight into the interaction between the carbon cycle and astronomical insolation forcing, we built a benthic carbon isotope (∂13Cbenthic) megasplice for the last 35 Ma, employing the same technique used to build the ∂18Obenthic megasplice. The ∂13Cbenthic megasplice exhibits a strong imprint of the 405 and 100-kyr eccentricity cycles throughout the last 35 Ma. This is intriguing, as the oxygen isotope megasplice looses its eccentricity imprint after the mid-Miocene climatic transition (MMCT; see Fig. 1 in De Vleeschouwer et al., 2017). In other words, the carbon cycle responded completely differently to astronomical forcing, compared to global climate during the late Miocene. We visualize this difference in response by the application of a Gaussian process, which renders the dependence of one variable (here ∂18Obenthic or ∂13Cbenthic) in a multidimensional space (here precession, obliquity and eccentricity). Together, the ∂13Cbenthic and ∂18Obenthic megasplices thus provide a unique tool for paleoclimatology, allowing for the quantification and visualization of the changing paleoclimate and carbon-cycle response to astronomical forcing throughout geologic time. References De Vleeschouwer, D., Vahlenkamp, M., Crucifix, M., Pälike, H., 2017. Alternating Southern and Northern Hemisphere climate response to astronomical forcing during the past 35 m

  8. A piecewise-integration method for simulating the influence of external forcing on climate

    Institute of Scientific and Technical Information of China (English)

    Zhifu Zhang; Chongjian Qiu; Chenghai Wang

    2008-01-01

    Climate drift occurs in most general circulation models (GCMs) as a result of incomplete physical and numerical representation of the complex climate system,which may cause large uncertainty in sensitivity experiments evaluating climate response to changes in external forcing.To solve this problem,we propose a piecewise-integration method to reduce the systematic error in climate sensitivity studies.The observations are firstly assimilated into a numerical model by using the dynamic relaxation technique to relax to the current state of atmosphere,and then the assimilated fields are continuously used to reinitialize the simulation to reduce the error of climate simulation.When the numerical model is integrated with changed external forcing,the results can be split into two parts,background and perturbation fields,and the background is the state before the external forcing is changed.The piecewise-integration method is used to continuously reinitialize the model with the assimilated field,instead of the background.Therefore,the simulation error of the model with the external forcing can be reduced.In this way,the accuracy of climate sensitivity experiments is greatly improved.Tests with a simple low-order spectral model show that this approach can significantly reduce the uncertainty of climate sensitivity experiments.

  9. Driving Forces Controlling Host-Guest Recognition in Supercritical Carbon Dioxide Solvent.

    Science.gov (United States)

    Ingrosso, Francesca; Altarsha, Muhannad; Dumarçay, Florence; Kevern, Gwendal; Barth, Danielle; Marsura, Alain; Ruiz-López, Manuel F

    2016-02-24

    The formation of supramolecular host-guest complexes is a very useful and widely employed tool in chemistry. However, supramolecular chemistry in non-conventional solvents such as supercritical carbon dioxide (scCO2 ), one of the most promising sustainable solvents, is still in its infancy. In this work, we explored a successful route to the development of green processes in supercritical CO2 by combining a theoretical approach with experiments. We were able to synthesize and characterize an inclusion complex between a polar aromatic molecule (benzoic acid) and peracetylated-β-cyclodextrin, which is soluble in the supercritical medium. This finding opens the way to wide, environmental friendly, applications of scCO2 in many areas of chemistry, including supramolecular synthesis, reactivity and catalysis, micro and nano-particle formation, molecular recognition, as well as enhanced extraction processes with increased selectivity. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Economic innovation and efficiency gains as the driving force for accelerating carbon dioxide emissions

    Science.gov (United States)

    Garrett, T. J.

    2012-12-01

    It is normally assumed that gains in energy efficiency are one of the best routes that society has available to it for stabilizing future carbon dioxide emissions. For a given degree of economic productivity less energy is consumed and a smaller quantity of fossil fuels is required. While certainly this observation is true in the instant, it ignores feedbacks in the economic system such that efficiency gains ultimately lead to greater energy consumption: taken as a global whole, they permit civilization to accelerate its expansion into the energy reserves that sustain it. Here this argument is formalized from a general thermodynamic perspective. The core result is that there exists a fixed, time-independent link between a very general representation of global inflation-adjusted economic wealth (units currency) and civilization's total capacity to consume power (units energy per time). Based on 40 years of available statistics covering more than a tripling of global GDP and a doubling of wealth, this constant has a value of 7.1 +/- 0.01 Watts per one thousand 2005 US dollars. Essentially, wealth is power. Civilization grows by dissipating power in order to sustain all its current activities and to incorporate more raw material into its existing structure. Growth of its structure is related to economic production, so more energy efficient economic production facilitates growth. Growth is into the reserves that sustain civilization, in which case there is a positive feedback in the economic system whereby energy efficiency gains ultimately "backfire" if their intended purpose is to reduce energy consumption and carbon dioxide emissions. The analogy that can be made is to a growing child: a healthy child who efficiently incorporates food into her structure grows quickly and is able to consume more in following years. Economically, an argument is made that, for a range of reasons, there are good reasons to refer to efficiency gains as economic "innovation", both for

  11. Differences in the efficacy of climate forcings explained by variations in atmospheric boundary layer depth.

    Science.gov (United States)

    Davy, Richard; Esau, Igor

    2016-05-25

    The Earth has warmed in the last century and a large component of that warming has been attributed to increased anthropogenic greenhouse gases. There are also numerous processes that introduce strong, regionalized variations to the overall warming trend. However, the ability of a forcing to change the surface air temperature depends on its spatial and temporal distribution. Here we show that the efficacy of a forcing is determined by the effective heat capacity of the atmosphere, which in cold and dry climates is defined by the depth of the planetary boundary layer. This can vary by an order of magnitude on different temporal and spatial scales, and so we get a strongly amplified temperature response in shallow boundary layers. This must be accounted for to assess the efficacy of a climate forcing, and also implies that multiple climate forcings cannot be linearly combined to determine the temperature response.

  12. Plastic-covered agriculture forces the regional climate to change

    Science.gov (United States)

    Yang, D.; Chen, J.; Chen, X.; Cao, X.

    2016-12-01

    The practice of plastic-covered agriculture as a solution to moderate the dilemma of global food shortage, meanwhile, brings great pressure to the local environment. This research was conducted to reveal the impacts of plastic-covered agritulture on regional climate change by experimenting in a plastic greenhouse (PG) dominated area - Weifang district, Shandong province, China. Based on a new plastic greenhouse index (PGI) proposed in this study, we reconstructed the spatial distribution of PG across 1995-2015 in the study area. With that, land surface temperature (LST) dataset combined with surface evapotranspiration, surface reflectance and precipitation data, was applied to the probe of PG's climatic impacts. Results showed that PG, in the study area, has experienced a striking spatial expansion during the past 20 years, and more important, the expansion correlated strongly to the local climate change. It showed that the annual precipitation, in the study area, decreased during these years, which constrasts to a slightly increasing trend of the adjacent districts without PG construction. In addition, resulting from the greenhouse effect, PG area presented a harsher increase of surface temperature compared to the non-PG areas. Our study also telled that the evapotranspiration of PG area has been largely cutted down ascribing to the gas tightness of plastic materials, showing a decline around 40%. This indicates a way that the development of plastic-covered agriculture may contribute to the change of the local climate.

  13. Toward a political analysis of the consequences of a world climate change produced by increasing atmospheric carbon dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Schware, R.

    1980-01-01

    It was Hegel's extraordinarily deep and perceptive insight that mankind is caught up in a drama that cannot be fully understood until it has been played out. The owl of Minewa spreads its wings only with the falling of the dusk. On the more hopeful side is the fact that, although we cannot know the consequences of future interactions between climate and society, we can begin to work toward political solutions and gird ourselves for ominous trends that are now coming into view. The purpose of this paper is to identify one such trend, namely the increase of atmospheric temperatures due to increased carbon dioxide (CO/sub 2/) and lay some initial groundwork for political research related to climate-societal interactions.

  14. Climate Forcing Datasets for Agricultural Modeling: Merged Products for Gap-Filling and Historical Climate Series Estimation

    Science.gov (United States)

    Ruane, Alex C.; Goldberg, Richard; Chryssanthacopoulos, James

    2014-01-01

    The AgMERRA and AgCFSR climate forcing datasets provide daily, high-resolution, continuous, meteorological series over the 1980-2010 period designed for applications examining the agricultural impacts of climate variability and climate change. These datasets combine daily resolution data from retrospective analyses (the Modern-Era Retrospective Analysis for Research and Applications, MERRA, and the Climate Forecast System Reanalysis, CFSR) with in situ and remotely-sensed observational datasets for temperature, precipitation, and solar radiation, leading to substantial reductions in bias in comparison to a network of 2324 agricultural-region stations from the Hadley Integrated Surface Dataset (HadISD). Results compare favorably against the original reanalyses as well as the leading climate forcing datasets (Princeton, WFD, WFD-EI, and GRASP), and AgMERRA distinguishes itself with substantially improved representation of daily precipitation distributions and extreme events owing to its use of the MERRA-Land dataset. These datasets also peg relative humidity to the maximum temperature time of day, allowing for more accurate representation of the diurnal cycle of near-surface moisture in agricultural models. AgMERRA and AgCFSR enable a number of ongoing investigations in the Agricultural Model Intercomparison and Improvement Project (AgMIP) and related research networks, and may be used to fill gaps in historical observations as well as a basis for the generation of future climate scenarios.

  15. Impact of climate forcing uncertainty and human water use on global and continental water balance components

    Directory of Open Access Journals (Sweden)

    H. Müller Schmied

    2016-10-01

    Full Text Available The assessment of water balance components using global hydrological models is subject to climate forcing uncertainty as well as to an increasing intensity of human water use within the 20th century. The uncertainty of five state-of-the-art climate forcings and the resulting range of cell runoff that is simulated by the global hydrological model WaterGAP is presented. On the global land surface, about 62 % of precipitation evapotranspires, whereas 38 % discharges into oceans and inland sinks. During 1971–2000, evapotranspiration due to human water use amounted to almost 1 % of precipitation, while this anthropogenic water flow increased by a factor of approximately 5 between 1901 and 2010. Deviation of estimated global discharge from the ensemble mean due to climate forcing uncertainty is approximately 4 %. Precipitation uncertainty is the most important reason for the uncertainty of discharge and evapotranspiration, followed by shortwave downward radiation. At continental levels, deviations of water balance components due to uncertain climate forcing are higher, with the highest discharge deviations occurring for river discharge in Africa (−6 to 11 % from the ensemble mean. Uncertain climate forcings also affect the estimation of irrigation water use and thus the estimated human impact of river discharge. The uncertainty range of global irrigation water consumption amounts to approximately 50 % of the global sum of water consumption in the other water use sector.

  16. On multi-fingerprint detection and attribution of greenhouse gas- and aerosol forced climate change

    Energy Technology Data Exchange (ETDEWEB)

    Hegerl, G C [Max-Planck-Institut fuer Meteorologie, Hamburg (Germany); Hasselmann, K [Max-Planck-Institut fuer Meteorologie, Hamburg (Germany); Cubasch, U [Deutsches Klimarechenzentrum (DKRZ), Hamburg (Germany); Mitchell, J F.B. [Hadley Centre for Climate Prediction and Research, Bracknell (United Kingdom). Meteorological Office; Roeckner, E [Max-Planck-Institut fuer Meteorologie, Hamburg (Germany); Voss, R [Deutsches Klimarechenzentrum (DKRZ), Hamburg (Germany); Waszkewitz, J [Deutsches Klimarechenzentrum (DKRZ), Hamburg (Germany)

    1996-07-01

    A multi-fingerprint analysis is applied to the detection and attribution of anthropogenic climate change. While a single fingerprint, as applied in a previous paper by Hegerl et al. (1996), is optimal for detecting a significant climate change, the simultaneous use of several fingerprints allows one to investigate additionally the consistency between observations and model predicted climate change signals for competing candidate forcing mechanisms. Thus the multi-fingerprint method is a particularly useful technique for attributing an observed climate change to a proposed cause. Different model-predicted climate change signals are derived from three global warming simulations for the period 1880 to 2049. In one simulation, the forcing was by greenhouse gases only, while in the remaining two simulations the influence of aerosols was also included. The two dominant climate change signals derived from these simulations are optimized statistically by weighting the model-predicted climate change pattern towards low-noise directions. These optimized fingerprints are then applied to observed near surface temperature trends. The space-time structure of natural climate variability (needed to determine the signal-to-noise ratio) is estimated from several multi-century control simulations with different CGCMs and from instrumental data over the last 134 years. (orig.)

  17. Do responses to different anthropogenic forcings add linearly in climate models?

    International Nuclear Information System (INIS)

    Marvel, Kate; Schmidt, Gavin A; LeGrande, Allegra N; Nazarenko, Larissa; Shindell, Drew; Bonfils, Céline; Tsigaridis, Kostas

    2015-01-01

    Many detection and attribution and pattern scaling studies assume that the global climate response to multiple forcings is additive: that the response over the historical period is statistically indistinguishable from the sum of the responses to individual forcings. Here, we use the NASA Goddard Institute for Space Studies (GISS) and National Center for Atmospheric Research Community Climate System Model (CCSM4) simulations from the CMIP5 archive to test this assumption for multi-year trends in global-average, annual-average temperature and precipitation at multiple timescales. We find that responses in models forced by pre-computed aerosol and ozone concentrations are generally additive across forcings. However, we demonstrate that there are significant nonlinearities in precipitation responses to different forcings in a configuration of the GISS model that interactively computes these concentrations from precursor emissions. We attribute these to differences in ozone forcing arising from interactions between forcing agents. Our results suggest that attribution to specific forcings may be complicated in a model with fully interactive chemistry and may provide motivation for other modeling groups to conduct further single-forcing experiments. (letter)

  18. Climate response to changes in atmospheric carbon dioxide and solar irradiance on the time scale of days to weeks

    International Nuclear Information System (INIS)

    Cao Long; Bala, Govindasamy; Caldeira, Ken

    2012-01-01

    Recent studies show that fast climate response on time scales of less than a month can have important implications for long-term climate change. In this study, we investigate climate response on the time scale of days to weeks to a step-function quadrupling of atmospheric CO 2 and contrast this with the response to a 4% increase in solar irradiance. Our simulations show that significant climate effects occur within days of a stepwise increase in both atmospheric CO 2 content and solar irradiance. Over ocean, increased atmospheric CO 2 warms the lower troposphere more than the surface, increasing atmospheric stability, moistening the boundary layer, and suppressing evaporation and precipitation. In contrast, over ocean, increased solar irradiance warms the lower troposphere to a much lesser extent, causing a much smaller change in evaporation and precipitation. Over land, both increased CO 2 and increased solar irradiance cause rapid surface warming that tends to increase both evaporation and precipitation. However, the physiological effect of increased atmospheric CO 2 on plant stomata reduces plant transpiration, drying the boundary layer and decreasing precipitation. This effect does not occur with increased solar irradiance. Therefore, differences in climatic effects from CO 2 versus solar forcing are manifested within days after the forcing is imposed. (letter)

  19. Electric cars : The climate impact of electric cars, focusing on carbon dioxide equivalent emissions

    OpenAIRE

    Ly, Sandra; Sundin, Helena; Thell, Linda

    2012-01-01

    This bachelor thesis examines and models the emissions of carbon dioxide equivalents of the composition of automobiles in Sweden 2012. The report will be based on three scenarios of electricity valuation principles, which are a snapshot perspective, a retrospective perspective and a future perspective. The snapshot perspective includes high and low values for electricity on the margin, the retrospective perspective includes Nordic and European electricity mix and the future perspective includ...

  20. Organic condensation - a vital link connecting aerosol formation to climate forcing

    Science.gov (United States)

    Riipinen, I.; Pierce, J. R.; Yli-Juuti, T.; Nieminen, T.; Häkkinen, S.; Ehn, M.; Junninen, H.; Lehtipalo, K.; Petäjä, T.; Slowik, J.; Chang, R.; Shantz, N. C.; Abbatt, J.; Leaitch, W. R.; Kerminen, V.-M.; Worsnop, D. R.; Pandis, S. N.; Donahue, N. M.; Kulmala, M.

    2011-01-01

    Atmospheric aerosol particles influence global climate as well as impair air quality through their effects on atmospheric visibility and human health. Ultrafine (<100 nm) particles often dominate aerosol numbers, and nucleation of atmospheric vapors is an important source of these particles. To have climatic relevance, however, the freshly-nucleated particles need to grow in size. We combine observations from two continental sites (Egbert, Canada and Hyytiälä, Finland) to show that condensation of organic vapors is a crucial factor governing the lifetimes and climatic importance of the smallest atmospheric particles. We demonstrate that state-of-the-science organic gas-particle partitioning models fail to reproduce the observations, and propose a modeling approach that is consistent with the measurements. We demonstrate the large sensitivity of climatic forcing of atmospheric aerosols to these interactions between organic vapors and the smallest atmospheric nanoparticles - highlighting the need for representing this process in global climate models.

  1. Drivers of 2016 record Arctic warmth assessed using climate simulations subjected to Factual and Counterfactual forcing

    Directory of Open Access Journals (Sweden)

    Lantao Sun

    2018-03-01

    Full Text Available A suite of historical atmospheric model simulations is described that uses a hierarchy of global boundary forcings designed to inform research on the detection and attribution of weather and climate-related extremes. In addition to experiments forced by actual variations in sea surface temperature, sea ice concentration, and atmospheric chemical composition (so-called Factual experiments; additional (Counterfactual experiments are conducted in which the boundary forcings are adjusted by removing estimates of long-term climate change. A third suite of experiments are identical to the Factual runs except that sea ice concentrations are set to climatological conditions (Clim-Polar experiments. These were used to investigate the cause for extremely warm Arctic surface temperature during 2016.Much of the magnitude of surface temperature anomalies averaged poleward of 65°N in 2016 (3.2 ± 0.6 °C above a 1980–89 reference is shown to have been forced by observed global boundary conditions. The Factual experiments reveal that at least three quarters of the magnitude of 2016 annual mean Arctic warmth was forced, with considerable sensitivity to assumptions of sea ice thickness change. Results also indicate that 30–40% of the overall forced Arctic warming signal in 2016 originated from drivers outside of the Arctic. Despite such remote effects, the experiments reveal that the extreme magnitude of the 2016 Arctic warmth could not have occurred without consideration of the Arctic sea ice loss. We find a near-zero probability for Arctic surface temperature to be as warm as occurred in 2016 under late-19th century boundary conditions, and also under 2016 boundary conditions that do not include the depleted Arctic sea ice. Results from the atmospheric model experiments are reconciled with coupled climate model simulations which lead to a conclusion that about 60% of the 2016 Arctic warmth was likely attributable to human-induced climate change

  2. Expert judgments about transient climate response to alternative future trajectories of radiative forcing.

    Science.gov (United States)

    Zickfeld, Kirsten; Morgan, M Granger; Frame, David J; Keith, David W

    2010-07-13

    There is uncertainty about the response of the climate system to future trajectories of radiative forcing. To quantify this uncertainty we conducted face-to-face interviews with 14 leading climate scientists, using formal methods of expert elicitation. We structured the interviews around three scenarios of radiative forcing stabilizing at different levels. All experts ranked "cloud radiative feedbacks" as contributing most to their uncertainty about future global mean temperature change, irrespective of the specified level of radiative forcing. The experts disagreed about the relative contribution of other physical processes to their uncertainty about future temperature change. For a forcing trajectory that stabilized at 7 Wm(-2) in 2200, 13 of the 14 experts judged the probability that the climate system would undergo, or be irrevocably committed to, a "basic state change" as > or =0.5. The width and median values of the probability distributions elicited from the different experts for future global mean temperature change under the specified forcing trajectories vary considerably. Even for a moderate increase in forcing by the year 2050, the medians of the elicited distributions of temperature change relative to 2000 range from 0.8-1.8 degrees C, and some of the interquartile ranges do not overlap. Ten of the 14 experts estimated that the probability that equilibrium climate sensitivity exceeds 4.5 degrees C is > 0.17, our interpretation of the upper limit of the "likely" range given by the Intergovernmental Panel on Climate Change. Finally, most experts anticipated that over the next 20 years research will be able to achieve only modest reductions in their degree of uncertainty.

  3. Using Demonstrations Involving Combustion and Acid-Base Chemistry to Show Hydration of Carbon Dioxide, Sulfur Dioxide, and Magnesium Oxide and Their Relevance for Environmental Climate Science

    Science.gov (United States)

    Shaw, C. Frank, III; Webb, James W.; Rothenberger, Otis

    2016-01-01

    The nature of acidic and basic (alkaline) oxides can be easily illustrated via a series of three straightforward classroom demonstrations for high school and general chemistry courses. Properties of carbon dioxide, sulfur dioxide, and magnesium oxide are revealed inexpensively and safely. Additionally, the very different kinetics of hydration of…

  4. A research program on radiative, chemical, and dynamical feedback progresses influencing the carbon dioxide and trace gases climate effects

    International Nuclear Information System (INIS)

    1989-07-01

    This report summarizes the up-to-date progress. The program includes two tasks: atmospheric radiation and climatic effects and their objective is to link quantitatively the radiation forcing changes and the climate responses caused by increasing greenhouse gases. Here, the objective and approach are described. We investigate the combined atmospheric radiation characteristics of the greenhouse gases (H 2 O, CO 2 , CH 4 , N 2 O, CFCs, and O 3 ), aerosols and clouds. Since the climatic effect of increasing atmospheric greenhouse gases is initiated by perturabtion to the longwave thermal radiation, it is critical to understand better the radiation characteristics of the greenhouse gases and their relationship to radiatively-important aerosols and clouds; the latter reflect solar radiation (a cooling of the surface) and provide a greenhouse effect (a warming to the surface). Therefore, aerosol and cloud particles are an integral part of the radiation field in the atmosphere. 9 refs

  5. Cloud forming properties of ambient aerosol in the Netherlands and resultant shortwave radiative forcing of climate

    NARCIS (Netherlands)

    Khlystov, A.

    1998-01-01

    This thesis discusses properties of ambient aerosols in the Netherlands which are controlling the magnitude of the local aerosol radiative forcing. Anthropogenic aerosols influence climate by changing the radiative transfer through the atmosphere via two effects, one is direct and a second

  6. A model perspective on orbital forcing of monsoons and Mediterranean climate using EC-Earth

    NARCIS (Netherlands)

    Bosmans, J.H.C.

    2014-01-01

    This thesis focuses on orbitally forced changes of monsoons and Mediterranean climate. Changes in the shape of the Earths orbit around the Sun and its rotational axis govern the seasonal and latitudinal distribution of incoming solar radiation on time scales of thousands to millions of years. The

  7. Climate forcing due to optimization of maximal leaf conductance in subtropical vegetation under rising CO2

    NARCIS (Netherlands)

    Boer, H.J. de; Lammertsma, E.I.; Wagner-Cremer, F.; Dilcher, D.L.; Wassen, M.J.; Dekker, S.C.

    2011-01-01

    Plant physiological adaptation to the global rise in atmospheric CO 2 concentration (CO2) is identified as a crucial climatic forcing. To optimize functioning under rising CO2, plants reduce the diffusive stomatal conductance of their leaves (gs) dynamically by closing stomata and structurally by

  8. Climate variability and physical forcing of the food webs and the carbon budget on panarctic shelves

    DEFF Research Database (Denmark)

    Carmack, Eddy; Barber, David; Christensen, Jens

    2006-01-01

    , which differ for different properties and shelf types, as do the likely responses; that is, the distributions of nutrients, organic carbon, freshwater, sediments, and trace minerals will all respond differently to climate forcing. A fundamental conclusion is that the changes associated with light...

  9. Climate forcing and infectious disease transmission in urban landscapes: integrating demographic and socioeconomic heterogeneity.

    Science.gov (United States)

    Santos-Vega, Mauricio; Martinez, Pamela P; Pascual, Mercedes

    2016-10-01

    Urbanization and climate change are the two major environmental challenges of the 21st century. The dramatic expansion of cities around the world creates new conditions for the spread, surveillance, and control of infectious diseases. In particular, urban growth generates pronounced spatial heterogeneity within cities, which can modulate the effect of climate factors at local spatial scales in large urban environments. Importantly, the interaction between environmental forcing and socioeconomic heterogeneity at local scales remains an open area in infectious disease dynamics, especially for urban landscapes of the developing world. A quantitative and conceptual framework on urban health with a focus on infectious diseases would benefit from integrating aspects of climate forcing, population density, and level of wealth. In this paper, we review what is known about these drivers acting independently and jointly on urban infectious diseases; we then outline elements that are missing and would contribute to building such a framework. © 2016 New York Academy of Sciences.

  10. Deployment of Low-Cost, Carbon Dioxide Sensors throughout the Washington Metropolitan Area - The Capital Climate Initiative

    Science.gov (United States)

    Caine, Kristen M.; Bailey, D. Michelle; Houston Miller, J.

    2016-04-01

    According to the IPCC from 1995 to 2005, atmospheric carbon dioxide (CO2) concentrations increased by 19 ppm, the highest average growth rate recorded for any decade since measurements began in the 1950s. Due to its ability to influence global climate change, it is imperative to continually monitor carbon dioxide emission levels, particularly in urban areas where some estimate in excess of 75% of total greenhouse gas emissions occur. Although high-precision sensors are commercially available, these are not cost effective for mapping a large spatial area. A goal of this research is to build out a network of sensors that are accurate and precise enough to provide a valuable data tool for accessing carbon emissions from a large, urban area. This publically available greenhouse gas dataset can be used in numerous environmental assessments and as validation for remote sensing products. It will also be a valuable teaching tool for classes at our university and will promote further engagement of K-12 students and their teachers through education and outreach activities. Each of our sensors (referred to as "PiOxides") utilizes a non-dispersive infrared (NDIR) sensor for the detection of carbon dioxide along with a combination pressure/temperature/humidity sensor. The collection of pressure and temperature increases the accuracy and precision of the CO2 measurement. The sensors communicate using a serial interfaces with a Raspberry Pi microcontroller. Each PiOxide is connected to a website that leverages recent developments in open source GIS tools. In this way, data from individual sensors can be followed individually or aggregated to provide real-time, spatially-resolved data of CO2 trends across a broad area. Our goal for the network is to expand across the entire DC/Maryland/Virginia Region through partnerships with private and public schools. We are also designing GHG Bluetooth beacons that may be accessed by mobile phone users in their vicinity. In two additional

  11. Modeling Climate Responses to Spectral Solar Forcing on Centennial and Decadal Time Scales

    Science.gov (United States)

    Wen, G.; Cahalan, R.; Rind, D.; Jonas, J.; Pilewskie, P.; Harder, J.

    2012-01-01

    We report a series of experiments to explore clima responses to two types of solar spectral forcing on decadal and centennial time scales - one based on prior reconstructions, and another implied by recent observations from the SORCE (Solar Radiation and Climate Experiment) SIM (Spectral 1rradiance Monitor). We apply these forcings to the Goddard Institute for Space Studies (GISS) Global/Middle Atmosphere Model (GCMAM). that couples atmosphere with ocean, and has a model top near the mesopause, allowing us to examine the full response to the two solar forcing scenarios. We show different climate responses to the two solar forCing scenarios on decadal time scales and also trends on centennial time scales. Differences between solar maximum and solar minimum conditions are highlighted, including impacts of the time lagged reSponse of the lower atmosphere and ocean. This contrasts with studies that assume separate equilibrium conditions at solar maximum and minimum. We discuss model feedback mechanisms involved in the solar forced climate variations.

  12. Attribution of soil moisture dynamics - Initial conditions vs. atmospheric forcing and the role of climate change

    Science.gov (United States)

    Orth, Rene; Seneviratne, Sonia I.

    2014-05-01

    The world's climate has started to change more quickly in recent decades and a stronger and faster shift is expected in the future. Even if the public perception is mostly limited to a widespread warming, climate change is a complex phenomenon impacting numerous variables of the climate system in different ways, also depending on time and location. Furthermore, extreme events may change more drastically than the mean climate. There is growing evidence that climate change is mostly man-made. However, it is still a matter of debate to which extent changes of the mean climate but also of particular (extreme) events are due to human impact. These questions are addressed by the growing science of climate attribution. Pointing out the anthropogenic influence on extreme events such as the 2010 Russian heatwave or the 2002 floods in Central Europe may help to support adaptation to climate change. This study investigates soil moisture in Europe in the context of climate change, because of its role as a key variable of the land-climate system and its practical importance for instance to agriculture. To derive soil moisture dynamics from 1984-2007 we use E-OBS forcing data together with SRB radiation data and employ an observation-based approach where soil moisture is computed from a water balance equation in which runoff (normalized with precipitation) and ET (normalized with net radiation) are simple functions of soil moisture. The constant runoff function is prescribed for the whole continent, and the ET function is calibrated using temperature data. After performing a validation of the inferred soil moisture data we use it in order to analyze changes in the likelihood of droughts. Our results show increased drought risk especially in north-eastern Europe and the Mediterranean, whereby the probability of extreme droughts increases stronger as for mild dryness episodes. To assess the potential for drought forecasting we furthermore study the importance of the initial

  13. Adaptation to climatic variability and change. Report of the task force on climate adaptation

    International Nuclear Information System (INIS)

    Smit, B.

    1994-01-01

    A critique and interpretation is presented of what is known and available about adaptation to climate changes, not based on any particular climate scenario. It is assumed that variability is a fact of climate and that changes in climatic conditions are possible and are constantly occurring. Emphasis is on adaptation with regard to economic and social activities in Canada. A series of linked objectives are addressed, relating to demonstration of the significance of adaptation, consideration of case studies of adaptation (past and potential future) in Canada, clarification of the meaning of adaptation and the forms it takes, assessment of policy implications, and identification of research priorities. The basic facts on global climate change are reviewed, including long-term temperature variations, and adaptation is discussed as a public policy response. Examples of adaptation in Canada are given in the areas of Great Lakes property, power generation, and transportation; Atlantic Canada communities and fisheries; forestry; the construction industry; the energy industry; recreation and tourism; agriculture; urban areas; and national defense. Recommendations regarding adapation are made to governments, the private sector, and researchers. An inventory of adaptation strategies for agriculture, the Arctic, coastal areas, ecosystems and land use, energy supply, fisheries, forestry, urban infrastructure, and water resources is appended

  14. Transdisciplinarity Within the North American Climate Change Mitigation Research Community, Specifically the Carbon Dioxide Capture, Transportation, Utilization and Storage Community

    Science.gov (United States)

    Carpenter, Steven Michael

    This research investigates the existence of and potential challenges to the development of a transdisciplinary approach to the climate change mitigation technology research focusing on carbon dioxide capture, utilization, and storage (CCUS) in North America. The unprecedented challenge of global climate change is one that invites a transdisciplinary approach. The challenge of climate change mitigation requires an understanding of multiple disciplines, as well as the role that complexity, post-normal or post-modern science, and uncertainty play in combining these various disciplines. This research followed the general discourse of transdisciplinarity as described by Klein (2014) and Augsburg (2016) which describe it as using transcendence, problem solving, and transgression to address wicked, complex societal problems, and as taught by California School of Transdisciplinarity, where the research focuses on sustainability in the age of post-normal science (Funtowicz & Ravetz, 1993). Through the use of electronic surveys and semi-structured interviews, members of the North American climate change mitigation research community shared their views and understanding of transdisciplinarity (Kvale & Brinkmann, 2009). The data indicate that much of the research currently being conducted by members of the North American CCUS research community is in fact transdisciplinary. What is most intriguing is the manner in which researchers arrived at their current understanding of transdisciplinarity, which is in many cases without any foreknowledge or use of the term transdisciplinary. The data reveals that in many cases the researchers now understand that this transdisciplinary approach is borne out of personal beliefs or emotion, social or societal aspects, their educational process, the way in which they communicate, and in most cases, the CCUS research itself, that require this transdisciplinary approach, but had never thought about giving it a name or understanding its origin or

  15. Northern Hemisphere forcing of Southern Hemisphere climate during the last deglaciation.

    Science.gov (United States)

    He, Feng; Shakun, Jeremy D; Clark, Peter U; Carlson, Anders E; Liu, Zhengyu; Otto-Bliesner, Bette L; Kutzbach, John E

    2013-02-07

    According to the Milankovitch theory, changes in summer insolation in the high-latitude Northern Hemisphere caused glacial cycles through their impact on ice-sheet mass balance. Statistical analyses of long climate records supported this theory, but they also posed a substantial challenge by showing that changes in Southern Hemisphere climate were in phase with or led those in the north. Although an orbitally forced Northern Hemisphere signal may have been transmitted to the Southern Hemisphere, insolation forcing can also directly influence local Southern Hemisphere climate, potentially intensified by sea-ice feedback, suggesting that the hemispheres may have responded independently to different aspects of orbital forcing. Signal processing of climate records cannot distinguish between these conditions, however, because the proposed insolation forcings share essentially identical variability. Here we use transient simulations with a coupled atmosphere-ocean general circulation model to identify the impacts of forcing from changes in orbits, atmospheric CO(2) concentration, ice sheets and the Atlantic meridional overturning circulation (AMOC) on hemispheric temperatures during the first half of the last deglaciation (22-14.3 kyr BP). Although based on a single model, our transient simulation with only orbital changes supports the Milankovitch theory in showing that the last deglaciation was initiated by rising insolation during spring and summer in the mid-latitude to high-latitude Northern Hemisphere and by terrestrial snow-albedo feedback. The simulation with all forcings best reproduces the timing and magnitude of surface temperature evolution in the Southern Hemisphere in deglacial proxy records. AMOC changes associated with an orbitally induced retreat of Northern Hemisphere ice sheets is the most plausible explanation for the early Southern Hemisphere deglacial warming and its lead over Northern Hemisphere temperature; the ensuing rise in atmospheric CO(2

  16. Sensitivity of tropical carbon to climate change constrained by carbon dioxide variability.

    Science.gov (United States)

    Cox, Peter M; Pearson, David; Booth, Ben B; Friedlingstein, Pierre; Huntingford, Chris; Jones, Chris D; Luke, Catherine M

    2013-02-21

    The release of carbon from tropical forests may exacerbate future climate change, but the magnitude of the effect in climate models remains uncertain. Coupled climate-carbon-cycle models generally agree that carbon storage on land will increase as a result of the simultaneous enhancement of plant photosynthesis and water use efficiency under higher atmospheric CO(2) concentrations, but will decrease owing to higher soil and plant respiration rates associated with warming temperatures. At present, the balance between these effects varies markedly among coupled climate-carbon-cycle models, leading to a range of 330 gigatonnes in the projected change in the amount of carbon stored on tropical land by 2100. Explanations for this large uncertainty include differences in the predicted change in rainfall in Amazonia and variations in the responses of alternative vegetation models to warming. Here we identify an emergent linear relationship, across an ensemble of models, between the sensitivity of tropical land carbon storage to warming and the sensitivity of the annual growth rate of atmospheric CO(2) to tropical temperature anomalies. Combined with contemporary observations of atmospheric CO(2) concentration and tropical temperature, this relationship provides a tight constraint on the sensitivity of tropical land carbon to climate change. We estimate that over tropical land from latitude 30° north to 30° south, warming alone will release 53 ± 17 gigatonnes of carbon per kelvin. Compared with the unconstrained ensemble of climate-carbon-cycle projections, this indicates a much lower risk of Amazon forest dieback under CO(2)-induced climate change if CO(2) fertilization effects are as large as suggested by current models. Our study, however, also implies greater certainty that carbon will be lost from tropical land if warming arises from reductions in aerosols or increases in other greenhouse gases.

  17. Atmospheric carbon dioxide and the long-term control of the Earth's climate

    Directory of Open Access Journals (Sweden)

    J. H. Carver

    1995-07-01

    Full Text Available A CO2-weathering model has been used to explore the possible evolution of the Earth's climate as the Sun steadily brightened throughout geologic time. The results of the model calculations can be described in terms of three, qualitatively different, "Megaclimates". Mega-climate 1 resulted from a period of rapid outgassing in the early Archean, with high, but declining, temperatures caused by the small weathering rates on a largely water-covered planet. Mega-climate 2 began about 3 Gyear ago as major continental land masses developed, increasing the weathering rate in the early Proterozoic and thereby depleting the atmospheric CO2 concentration. This process produced the first Precambrian glaciations about 2.3 Gyear ago. During Mega-climate 2, evolutionary biological processes increased the surface weatherability in incremental steps and plate tectonics modulated the CO2 outgassing rate with an estimated period of 150 Myear (approximately one-half the period for the formation and breakup of super continents. Throughout Mega-climate 2 the surface temperature was controlled by variations in the atmospheric CO2 level allowing transitions between glacial and non-glacial conditions. The results of the model for Mega-climate 2 are in agreement with the occurrence (and absence of glaciations in the geologic record. Extending the model to the future suggests that CO2 control of the Earth's temperature will no longer be able to compensate for a solar flux that continues to increase. The present level of atmospheric CO2 is so small that further reduction in CO2 cannot prevent the Earth from experiencing Mega-climate 3 with steadily increasing surface temperatures caused by the continued brightening of the Sun. During Mega-climate 3, the main danger to the biosphere would come not from an increasing temperature but from a decreasing (rather than an increasing CO2 level which could, in time, fall below 0.5 PAL, causing serious damage to the biosphere

  18. Atmospheric carbon dioxide and the long-term control of the Earth's climate

    Directory of Open Access Journals (Sweden)

    J. H. Carver

    Full Text Available A CO2-weathering model has been used to explore the possible evolution of the Earth's climate as the Sun steadily brightened throughout geologic time. The results of the model calculations can be described in terms of three, qualitatively different, "Megaclimates". Mega-climate 1 resulted from a period of rapid outgassing in the early Archean, with high, but declining, temperatures caused by the small weathering rates on a largely water-covered planet. Mega-climate 2 began about 3 Gyear ago as major continental land masses developed, increasing the weathering rate in the early Proterozoic and thereby depleting the atmospheric CO2 concentration. This process produced the first Precambrian glaciations about 2.3 Gyear ago. During Mega-climate 2, evolutionary biological processes increased the surface weatherability in incremental steps and plate tectonics modulated the CO2 outgassing rate with an estimated period of 150 Myear (approximately one-half the period for the formation and breakup of super continents. Throughout Mega-climate 2 the surface temperature was controlled by variations in the atmospheric CO2 level allowing transitions between glacial and non-glacial conditions. The results of the model for Mega-climate 2 are in agreement with the occurrence (and absence of glaciations in the geologic record. Extending the model to the future suggests that CO2 control of the Earth's temperature will no longer be able to compensate for a solar flux that continues to increase. The present level of atmospheric CO2 is so small that further reduction in CO2 cannot prevent the Earth from experiencing Mega-climate 3 with steadily increasing surface temperatures caused by the continued brightening of the Sun. During Mega-climate 3, the main danger to the biosphere would come not from an increasing temperature but from a decreasing (rather than an increasing CO2

  19. On the Representation of Cloud Phase in Global Climate Models, and its Importance for Simulations of Climate Forcings and Feedbacks

    Science.gov (United States)

    Storelvmo, Trude; Sagoo, Navjit; Tan, Ivy

    2016-04-01

    Despite the growing effort in improving the cloud microphysical schemes in GCMs, most of this effort has not focused on improving the ability of GCMs to accurately simulate phase partitioning in mixed-phase clouds. Getting the relative proportion of liquid droplets and ice crystals in clouds right in GCMs is critical for the representation of cloud radiative forcings and cloud-climate feedbacks. Here, we first present satellite observations of cloud phase obtained by NASA's CALIOP instrument, and report on robust statistical relationships between cloud phase and several aerosols species that have been demonstrated to act as ice nuclei (IN) in laboratory studies. We then report on results from model intercomparison projects that reveal that GCMs generally underestimate the amount of supercooled liquid in clouds. For a selected GCM (NCAR 's CAM5), we thereafter show that the underestimate can be attributed to two main factors: i) the presence of IN in the mixed-phase temperature range, and ii) the Wegener-Bergeron-Findeisen process, which converts liquid to ice once ice crystals have formed. Finally, we show that adjusting these two processes such that the GCM's cloud phase is in agreement with the observed has a substantial impact on the simulated radiative forcing due to IN perturbations, as well as on the cloud-climate feedbacks and ultimately climate sensitivity simulated by the GCM.

  20. Carbon Dioxide Effects Research and Assessment Program. Environmental and societal consequences of a possible CO/sub 2//sup -/ induced climate change: a research agenda

    Energy Technology Data Exchange (ETDEWEB)

    1980-12-01

    In adding carbon dioxide to the atmosphere, mankind is unintentionally conducting a great biological and geophysical experiment. This experiment can be expected to increase scientific understanding of ecological systems and of the processes in the ocean and the atmosphere that partially determine world climate. But from the standpoint of governments and peoples, the major problem to be solved is to understand the nature of the impacts on societies of rising levels of atmospheric carbon dioxide (CO/sub 2/), with the objective of avoiding or ameliorating unfavorable impacts and gaining most benefit from favorable impacts. The research program proposed herein is designed to provide the understanding needed to achieve this objective. It is based on a recognition of the distinctive characteristics of the CO/sub 2/ problem. It is concluded that three kinds of research on the consequences of rising levels of atmospheric carbon dioxide and possible climatic changes are called for: assessment of risks; research to enhance beneficial effects and lessen harmful ones, where this is possible, and to slow down rates of carbon dioxide emission; and study of potential social and institutional responses to projected climatic changes.

  1. Easy Volcanic Aerosol (EVA v1.0: an idealized forcing generator for climate simulations

    Directory of Open Access Journals (Sweden)

    M. Toohey

    2016-11-01

    Full Text Available Stratospheric sulfate aerosols from volcanic eruptions have a significant impact on the Earth's climate. To include the effects of volcanic eruptions in climate model simulations, the Easy Volcanic Aerosol (EVA forcing generator provides stratospheric aerosol optical properties as a function of time, latitude, height, and wavelength for a given input list of volcanic eruption attributes. EVA is based on a parameterized three-box model of stratospheric transport and simple scaling relationships used to derive mid-visible (550 nm aerosol optical depth and aerosol effective radius from stratospheric sulfate mass. Precalculated look-up tables computed from Mie theory are used to produce wavelength-dependent aerosol extinction, single scattering albedo, and scattering asymmetry factor values. The structural form of EVA and the tuning of its parameters are chosen to produce best agreement with the satellite-based reconstruction of stratospheric aerosol properties following the 1991 Pinatubo eruption, and with prior millennial-timescale forcing reconstructions, including the 1815 eruption of Tambora. EVA can be used to produce volcanic forcing for climate models which is based on recent observations and physical understanding but internally self-consistent over any timescale of choice. In addition, EVA is constructed so as to allow for easy modification of different aspects of aerosol properties, in order to be used in model experiments to help advance understanding of what aspects of the volcanic aerosol are important for the climate system.

  2. Is climate change an unforeseen, irresistible and external factor - A force majeure in marine environmental law?

    Science.gov (United States)

    Saul, Roxanne; Barnes, Richard; Elliott, Michael

    2016-12-15

    Several environmental laws include provisions on natural causes or force majeure, which except States from their commitments if it can be proven that the failure to meet the commitment is due to factors outside their control. The European Union Marine Strategy Framework Directive (MSFD) has a pivotal role in managing EU marine waters. This paper analyses natural causes and force majeure provisions of the MFSD and other marine legislation, and addresses their interaction with climate change and its consequences, especially the effect on the obligation of ensuring seas are in Good Environmental Status. Climate change is an exogenic unmanaged pressure in that it emanates from outside the area being managed but in which the management authority has to respond to the consequences of climate change, such as sea level rise and temperature elevation, rather than its causes. It is suggested that a defence by a Member State of force majeure may be accepted if an event was proven to be due to an externality of control, irresistible and unforeseeable. The analysis contends that countering such a legal defence would centre on the fact that climate change is a well-accepted phenomenon, is foreseen with an accepted level of confidence and probability and is due to human actions. However, as yet, this has not been legally tested. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Improved attribution of climate forcing to emissions by pollutant and sector

    Science.gov (United States)

    Shindell, D. T.

    2009-12-01

    Evaluating multi-component climate change mitigation strategies requires knowledge of the diverse direct and indirect effects of emissions. Methane, ozone and aerosols are linked through atmospheric chemistry so that emissions of a single pollutant can affect several species. I will show new calculations of atmospheric composition changes, radiative forcing, and the global warming potential (GWP) for increased emissions of tropospheric ozone and aerosol precursors in a coupled composition-climate model. The results demonstrate that gas-aerosol interactions substantially alter the relative importance of the various emissions, suggesting revisions to the GWPs used in international carbon trading. Additionally, I will present results showing how the net climate impact of particular activities depends strongly upon non-CO2 forcing agents for some sectors. These results will be highlighted by discussing the interplay between air quality emissions controls and climate for the case of emissions from coal-fired power plants. The changing balance between CO2 and air quality pollutants from coal plants may have contributed to the 20th century spatial and temporal patterns of climate change, and is likely to continue to do so as more and more plants are constructed in Asia.

  4. Emerging patterns of simulated regional climatic changes for the 21st century due to anthropogenic forcings

    DEFF Research Database (Denmark)

    Giorgi, Filippo; Whetton, Peter H.; Jones, Richard G.

    2001-01-01

    We analyse temperature and precipitation changes for the late decades of the 21st century (with respect to present day conditions) over 23 land regions of the world from 18 recent transient, climate change experiments with coupled atmosphere-ocean General Circulation Models (AOGCMs). The analysis...... involves two different forcing scenarios and nine models, and it focuses on model agreement in the simulated regional changes for the summer and winter seasons. While to date very few conclusions have been presented on regional climatic changes, mostly limited to some broad latitudinal bands, our analysis...

  5. On the Representation of Ice Nucleation in Global Climate Models, and its Importance for Simulations of Climate Forcings and Feedbacks

    Science.gov (United States)

    Storelvmo, T.

    2015-12-01

    Substantial improvements have been made to the cloud microphysical schemes used in the latest generation of global climate models (GCMs), however, an outstanding weakness of these schemes lies in the arbitrariness of their tuning parameters. Despite the growing effort in improving the cloud microphysical schemes in GCMs, most of this effort has not focused on improving the ability of GCMs to accurately simulate phase partitioning in mixed-phase clouds. Getting the relative proportion of liquid droplets and ice crystals in clouds right in GCMs is critical for the representation of cloud radiative forcings and cloud-climate feedbacks. Here, we first present satellite observations of cloud phase obtained by NASA's CALIOP instrument, and report on robust statistical relationships between cloud phase and several aerosols species that have been demonstrated to act as ice nuclei (IN) in laboratory studies. We then report on results from model intercomparison projects that reveal that GCMs generally underestimate the amount of supercooled liquid in clouds. For a selected GCM (NCAR 's CAM5), we thereafter show that the underestimate can be attributed to two main factors: i) the presence of IN in the mixed-phase temperature range, and ii) the Wegener-Bergeron-Findeisen process, which converts liquid to ice once ice crystals have formed. Finally, we show that adjusting these two processes such that the GCM's cloud phase is in agreement with the observed has a substantial impact on the simulated radiative forcing due to IN perturbations, as well as on the cloud-climate feedbacks and ultimately climate sensitivity simulated by the GCM.

  6. Direct shortwave forcing of climate by anthropogenic sulfate aerosol: Sensitivity to particle size, composition, and relative humidity

    Energy Technology Data Exchange (ETDEWEB)

    Nemesure, S.; Wagener, R.; Schwartz, S.E. [Brookhaven National Lab., Upton, New York (United States)

    1996-04-01

    Recent estimates of global or hemispheric average forcing of climate by anthropogenic sulfate aerosol due to scattering of shortwave radiation are uncertain by more than a factor of 2. This paper examines the sensitivity of forcing to these microphysical properties for the purposes of obtaining a better understanding of the properties required to reduce the uncertainty in the forcing.

  7. Relevance of land forcings and feedbacks in the attribution of climate extremes

    Science.gov (United States)

    Seneviratne, S. I.; Davin, E.; Greve, P.; Gudmundsson, L.; Hauser, M.; Hirschi, M.; Mueller, B.; Orlowsky, B.; Orth, R.

    2014-12-01

    Land forcings and feedbacks play an important role in the climate system, in particular for the occurrence of climate extremes. Recent investigations have for instance highlighted the impacts of soil moisture-climate interactions for the development of droughts and heat waves (e.g. Seneviratne et al. 2012, Mueller and Seneviratne 2012, Seneviratne et al. 2013, Orlowsky and Seneviratne 2013). In addition, forcing from land use and land cover changes through modified albedo or turbulent fluxes can also affect the temperature variability in summer (Davin et al. 2014). These effects are important for better understanding the relationships between climate forcing and regional climate changes, and appear relevant for a recent discrepancy between trends in global mean temperature vs hot extremes over land (Seneviratne et al. 2014). This presentation will provide an overview on the underlying processes and on possible approaches for their consideration in attribution research. References:- Davin, E.L., S.I. Seneviratne, P. Ciais, A. Olioso, T. Wang, 2014: Preferential cooling of hot extremes from cropland albedo management. Proc. Natl. Acad. Sci., Published ahead of print June 23, 2014.- Mueller, B., and S.I. Seneviratne, 2012: Hot days induced by precipitation deficits at the global scale. Proceedings of the National Academy of Sciences, 109 (31), 12398-12403, doi: 10.1073/pnas.1204330109.- Orlowsky, B., and S.I. Seneviratne, 2013: Elusive drought: Uncertainty in observed trends and short- and long-term CMIP5 projections. Hydr. Earth Syst. Sci., 17, 1765-1781, doi:10.5194/hess-17-1765-2013- Seneviratne, S.I., N. Nicholls, et al., 2012: Changes in climate extremes and their impacts on the natural physical environment. In: Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation [Field, C.B., et al. (eds.)]. A Special Report of Working Groups I and II of the Intergovernmental Panel on Climate Change, pp. 109-230.- Seneviratne, S.I., et al

  8. Sensitivity of the Greenland Ice Sheet to Interglacial Climate Forcing: MIS 5e Versus MIS 11

    Science.gov (United States)

    Rachmayani, Rima; Prange, Matthias; Lunt, Daniel J.; Stone, Emma J.; Schulz, Michael

    2017-11-01

    The Greenland Ice Sheet (GrIS) is thought to have contributed substantially to high global sea levels during the interglacials of Marine Isotope Stage (MIS) 5e and 11. Geological evidence suggests that the mass loss of the GrIS was greater during the peak interglacial of MIS 11 than MIS 5e, despite a weaker boreal summer insolation. We address this conundrum by using the three-dimensional thermomechanical ice sheet model Glimmer forced by Community Climate System Model version 3 output for MIS 5e and MIS 11 interglacial time slices. Our results suggest a stronger sensitivity of the GrIS to MIS 11 climate forcing than to MIS 5e forcing. Besides stronger greenhouse gas radiative forcing, the greater MIS 11 GrIS mass loss relative to MIS 5e is attributed to a larger oceanic heat transport toward high latitudes by a stronger Atlantic meridional overturning circulation. The vigorous MIS 11 ocean overturning, in turn, is related to a stronger wind-driven salt transport from low to high latitudes promoting North Atlantic Deep Water formation. The orbital insolation forcing, which causes the ocean current anomalies, is discussed.

  9. Meeting the Radiative Forcing Targets of the Representative Concentration Pathways with Agricultural Climate Impacts

    Science.gov (United States)

    Kyle, P.; Müller, C.; Calvin, K. V.; Thomson, A. M.

    2013-12-01

    The Representative Concentration Pathways (RCPs) have formed the basis for much of the current scientific understanding of future climate change impacts and mitigation. However, the emissions scenarios underlying the RCPs were produced by integrated assessment models that did not include impacts of future climate change on the modeled evolution of the agricultural and energy systems. Given the prominent role of bioenergy in greenhouse gas emissions mitigation, and given the importance of land-use-related emissions in determining future atmospheric CO2 concentrations, it is possible that agricultural climate impacts may cause significant changes to the means and costs of mitigating greenhouse gas emissions. This study builds on several international modeling exercises aimed at improving understanding of climate change impacts--CMIP-5 and ISI-MIP--that have generated global gridded climate impacts on yields of major agricultural crops in each of the four RCPs. We use the climate outcomes from the HadGEM2-ES climate model, and the agricultural yield outcomes from the LPJmL crop growth model to inform inputs to the GCAM integrated assessment model, allowing analysis of how agricultural climate impacts may affect the long-term global and regional strategies for achieving the greenhouse gas concentration pathways of the RCPs. Our results indicate that for this combination of models and emissions scenarios, strongly negative climate impacts on several major commodity classes--prominently cereals and oil seeds, and particularly in the high-radiative-forcing RCPs--lead to a long-term increase in cropland and therefore land-use-related CO2 emissions. All else equal, this increases the emissions mitigation burden on the rest of the system, and therefore increases total net costs of emissions mitigation. However, the future climate change impacts on C4 bioenergy crops tend to be positive, limiting the shock of agricultural climate impacts on the modeled energy supply and

  10. Reduction of systematic biases in regional climate downscaling through ensemble forcing

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Hongwei; Wang, Bin [Chinese Academy of Sciences, LASG, Institute of Atmospheric Physics, Beijing (China); Wang, Bin [University of Hawaii at Manoa, Department of Meteorology, Honolulu, Hawaii (United States); University of Hawaii at Manoa, International Pacific Research Center, Honolulu, Hawaii (United States)

    2012-02-15

    Simulations of the East Asian summer monsoon for the period of 1979-2001 were carried out using the Weather Research and Forecast (WRF) model forced by three reanalysis datasets (NCEP-R2, ERA-40, and JRA-25). The experiments forced by different reanalysis data exhibited remarkable differences, primarily caused by uncertainties in the lateral boundary (LB) moisture fluxes over the Bay of Bengal and the Philippine Sea. The climatological mean water vapor convergence into the model domain computed from ERA-40 was about 24% higher than that from the NCEP-R2 reanalysis. We demonstrate that using the ensemble mean of NCEP-R2, ERA-40, and JRA-25 as LB forcing considerably reduced the biases in the model simulation. The use of ensemble forcing improved the performance in simulated mean circulation and precipitation, inter-annual variation in seasonal precipitation, and daily precipitation. The model simulated precipitation was superior to that in the reanalysis in both climatology and year-to-year variations, indicating the added value of dynamic downscaling. The results suggest that models having better performance under one set of LB forcing might worsen when another set of reanalysis data is used as LB forcing. Use of ensemble mean LB forcing for assessing regional climate model performance is recommended. (orig.)

  11. The Role of Forcing and Internal Dynamics in explaining the 'Medieval Climate Anomaly'

    Science.gov (United States)

    Goossee, Hugues; Crespin, Elisabeth; Dubinkina, Svetlana; Loutre, Marie-France; Mann, Michael E.; Renssen, Hans; Shindell, Drew

    2012-01-01

    Proxy reconstructions suggest that peak global temperature during the past warm interval known as the Medieval Climate Anomaly (MCA, roughly 950-1250 AD) has been exceeded only during the most recent decades. To better understand the origin of this warm period, we use model simulations constrained by data assimilation establishing the spatial pattern of temperature changes that is most consistent with forcing estimates, model physics and the empirical information contained in paleoclimate proxy records. These numerical experiments demonstrate that the reconstructed spatial temperature pattern of the MCA can be explained by a simple thermodynamical response of the climate system to relatively weak changes in radiative forcing combined with a modification of the atmospheric circulation, displaying some similarities with the positive phase of the so-called Arctic Oscillation, and with northward shifts in the position of the Gulf Stream and Kuroshio currents. The mechanisms underlying the MCA are thus quite different from anthropogenic mechanisms responsible for modern global warming.

  12. The impact of international shipping on European air quality and climate forcing

    Energy Technology Data Exchange (ETDEWEB)

    van Aardenne, J. [European Environment Agency (EEA), Copenhagen (Denmark); Colette, A. [INERIS (France); Degraeuwe, B.; de Vlieger, I. [VITO (Belgium); Hammingh, P. [PBL Netherlands Environmental Assessment Agency (Netherlands); Viana, M. [CSIC (Spain)

    2013-03-15

    This EEA Technical report provides an overview on the state of knowledge on the impact of international shipping in European waters to air quality and climate change. Based on literature review and model assessment studies information is provided on past and future emissions of air pollutants and greenhouse gases, monitoring of ship emissions, emission mitigation policies and impact on European air quality and radiative forcing. (Author)

  13. Recent advances in understanding secondary organic aerosol: Implications for global climate forcing

    Science.gov (United States)

    Shrivastava, Manish; Cappa, Christopher D.; Fan, Jiwen; Goldstein, Allen H.; Guenther, Alex B.; Jimenez, Jose L.; Kuang, Chongai; Laskin, Alexander; Martin, Scot T.; Ng, Nga Lee; Petaja, Tuukka; Pierce, Jeffrey R.; Rasch, Philip J.; Roldin, Pontus; Seinfeld, John H.; Shilling, John; Smith, James N.; Thornton, Joel A.; Volkamer, Rainer; Wang, Jian; Worsnop, Douglas R.; Zaveri, Rahul A.; Zelenyuk, Alla; Zhang, Qi

    2017-06-01

    Anthropogenic emissions and land use changes have modified atmospheric aerosol concentrations and size distributions over time. Understanding preindustrial conditions and changes in organic aerosol due to anthropogenic activities is important because these features (1) influence estimates of aerosol radiative forcing and (2) can confound estimates of the historical response of climate to increases in greenhouse gases. Secondary organic aerosol (SOA), formed in the atmosphere by oxidation of organic gases, represents a major fraction of global submicron-sized atmospheric organic aerosol. Over the past decade, significant advances in understanding SOA properties and formation mechanisms have occurred through measurements, yet current climate models typically do not comprehensively include all important processes. This review summarizes some of the important developments during the past decade in understanding SOA formation. We highlight the importance of some processes that influence the growth of SOA particles to sizes relevant for clouds and radiative forcing, including formation of extremely low volatility organics in the gas phase, acid-catalyzed multiphase chemistry of isoprene epoxydiols, particle-phase oligomerization, and physical properties such as volatility and viscosity. Several SOA processes highlighted in this review are complex and interdependent and have nonlinear effects on the properties, formation, and evolution of SOA. Current global models neglect this complexity and nonlinearity and thus are less likely to accurately predict the climate forcing of SOA and project future climate sensitivity to greenhouse gases. Efforts are also needed to rank the most influential processes and nonlinear process-related interactions, so that these processes can be accurately represented in atmospheric chemistry-climate models.

  14. The influence of cirrus cloud-radiative forcing on climate and climate sensitivity in a general circulation model

    International Nuclear Information System (INIS)

    Lohmann, U.; Roeckner, E.

    1994-01-01

    Six numerical experiments have been performed with a general circulation model (GCM) to study the influence of high-level cirrus clouds and global sea surface temperature (SST) perturbations on climate and climate sensitivity. The GCM used in this investigation is the third-generation ECHAM3 model developed jointly by the Max-Planck-Institute for Meteorology and the University of Hamburg. It is shown that the model is able to reproduce many features of the observed cloud-radiative forcing with considerable skill, such as the annual mean distribution, the response to seasonal forcing and the response to observed SST variations in the equatorial Pacific. In addition to a reference experiment where the cirrus emissivity is computed as a function of the cloud water content, two sensitivity experiments have been performed in which the cirrus emissivity is either set to zero everywhere above 400 hPa ('transparent cirrus') or set to one ('black cirrus'). These three experiments are repeated identically, except for prescribing a globally uniform SST warming of 4 K. (orig.)

  15. Reflections on the nature of non-linear responses of the climate to forcing

    Science.gov (United States)

    Ditlevsen, Peter

    2017-04-01

    On centennial to multi-millennial time scales the paleoclimatic record shows that climate responds in a very non-linear way to the external forcing. Perhaps most puzzling is the change in glacial period duration at the Middle Pleistocene Transition. From a dynamical systems perspective, this could be a change in frequency locking between the orbital forcing and the climatic response or it could be a non-linear resonance phenomenon. In both cases the climate system shows a non-trivial oscillatory behaviour. From the records it seems that this behaviour can be described by an effective dynamics on a low-dimensional slow manifold. These different possible dynamical behaviours will be discussed. References: Arianna Marchionne, Peter Ditlevsen, and Sebastian Wieczorek, "Three types of nonlinear resonances", arXiv:1605.00858 Peter Ashwin and Peter Ditlevsen, "The middle Pleistocene transition as a generic bifurcation on a slow manifold", Climate Dynamics, 45, 2683, 2015. Peter D. Ditlevsen, "The bifurcation structure and noise assisted transitions in the Pleistocene glacial cycles", Paleoceanography, 24, PA3204, 2009

  16. Seasonal changes in the human alteration of fire regimes beyond the climate forcing

    Science.gov (United States)

    Fréjaville, Thibaut; Curt, Thomas

    2017-03-01

    Human activities have altered fire regimes for millennia by suppressing or enhancing natural fire activity. However, whether these anthropogenic pressures on fire activity have exceeded and will surpass climate forcing still remains uncertain. We tested if, how and the extent to which seasonal fire activity in southern France has recently (1976-2009) deviated from climate-expected trends. The latter were simulated using an ensemble of detrended fire-climate models. We found both seasonal and regional contrasts in climatic effects through a mixture of drought-driven and fuel-limited fire regimes. Dry contemporary conditions chiefly drove fire frequency and burned area, although higher fire activity was related to wetter conditions in the last three years. Surprisingly, the relative importance of preceding wet conditions was higher in winter than in summer, illustrating the strong potential dependency of regional fire-climate relationships on the human use and control of fires. In the Mediterranean mountains, warm winters and springs favour extensive fires in the following dry summer. These results highlight that increasing dryness with climate change could have antagonistic effects on fire regime by leading to larger fires in summer (moisture-limited), but lower fire activity in winter (fuel-limited fire regime). Furthermore, fire trends have significantly diverged from climatic expectations, with a strong negative alteration in fire activity in the Mediterranean lowlands and the summer burned area in the mountains. In contrast, alteration of winter fire frequency in the Mediterranean and Temperate mountains has shifted from positive to negative (or null) trends during the mid-1990s, a period when fire suppression policy underwent major revisions. Our findings demonstrate that changes in land-use and fire suppression policy have probably exceeded the strength of climate change effects on changing fire regime in southern Europe, making regional predictions of future

  17. Assessment of the possible future climatic impact of carbon dioxide increases based on a coupled one-dimensional atmospheric-oceanic model

    International Nuclear Information System (INIS)

    Hunt, B.G.; Wells, N.C.

    1979-01-01

    A radiative-convective equilibrium model of the atmosphere has been coupled with a mixed layer model of the ocean to investigate the response of this one-dimensional system to increasing carbon dioxide amounts in the atmosphere. For global mean conditions a surface temperature rise of about 2 0 K was obtained for a doubling of the carbon dioxide amount, in reasonable agreement with the commonly accepted results of Manabe and Wetherald. This temperature rise was essentially invariant with season and indicates that including a shallow (300 m) ocean slab in this problem does not basically alter previous assessments. While the mixed layer depth of the ocean was only very slightly changed by the temperature increase, which extended throughout the depth of the mixed layer, the impact of this increase on the overall behavior of the ocean warrants further study. A calculation was also made of the temporal variation of the sea surface temperature for three possible carbon dioxide growth rates starting from an initial carbon dioxide content of 300 ppm. This indicated that the thermal inertia of the slab ocean provides a time lag of 8 years in the sea surface temperature response compared to a land situation. This is not considered to be of great significance as regards the likely future climatic impact of carbon dioxide increase

  18. CO2 forcing induces semi-direct effects with consequences for climate feedback interpretations

    Science.gov (United States)

    Andrews, Timothy; Forster, Piers M.

    2008-02-01

    Climate forcing and feedbacks are diagnosed from seven slab-ocean GCMs for 2 × CO2 using a regression method. Results are compared to those using conventional methodologies to derive a semi-direct forcing due to tropospheric adjustment, analogous to the semi-direct effect of absorbing aerosols. All models show a cloud semi-direct effect, indicating a rapid cloud response to CO2; cloud typically decreases, enhancing the warming. Similarly there is evidence of semi-direct effects from water-vapour, lapse-rate, ice and snow. Previous estimates of climate feedbacks are unlikely to have taken these semi-direct effects into account and so misinterpret processes as feedbacks that depend only on the forcing, but not the global surface temperature. We show that the actual cloud feedback is smaller than what previous methods suggest and that a significant part of the cloud response and the large spread between previous model estimates of cloud feedback is due to the semi-direct forcing.

  19. Trade-offs for food production, nature conservation and climate limit the terrestrial carbon dioxide removal potential.

    Science.gov (United States)

    Boysen, Lena R; Lucht, Wolfgang; Gerten, Dieter

    2017-10-01

    Large-scale biomass plantations (BPs) are a common factor in climate mitigation scenarios as they promise double benefits: extracting carbon from the atmosphere and providing a renewable energy source. However, their terrestrial carbon dioxide removal (tCDR) potentials depend on important factors such as land availability, efficiency of capturing biomass-derived carbon and the timing of operation. Land availability is restricted by the demands of future food production depending on yield increases and population growth, by requirements for nature conservation and, with respect to climate mitigation, avoiding unfavourable albedo changes. We integrate these factors in one spatially explicit biogeochemical simulation framework to explore the tCDR opportunity space on land available after these constraints are taken into account, starting either in 2020 or 2050, and lasting until 2100. We find that assumed future needs for nature protection and food production strongly limit tCDR potentials. BPs on abandoned crop and pasture areas (~1,300 Mha in scenarios of either 8.0 billion people and yield gap reductions of 25% until 2020 or 9.5 billion people and yield gap reductions of 50% until 2050) could, theoretically, sequester ~100 GtC in land carbon stocks and biomass harvest by 2100. However, this potential would be ~80% lower if only cropland was available or ~50% lower if albedo decreases were considered as a factor restricting land availability. Converting instead natural forest, shrubland or grassland into BPs could result in much larger tCDR potentials ̶ but at high environmental costs (e.g. biodiversity loss). The most promising avenue for effective tCDR seems to be improvement of efficient carbon utilization pathways, changes in dietary trends or the restoration of marginal lands for the implementation of tCDR. © 2017 John Wiley & Sons Ltd.

  20. How realistic are air quality hindcasts driven by forcings from climate model simulations?

    Science.gov (United States)

    Lacressonnière, G.; Peuch, V.-H.; Arteta, J.; Josse, B.; Joly, M.; Marécal, V.; Saint Martin, D.; Déqué, M.; Watson, L.

    2012-12-01

    Predicting how European air quality could evolve over the next decades in the context of changing climate requires the use of climate models to produce results that can be averaged in a climatologically and statistically sound manner. This is a very different approach from the one that is generally used for air quality hindcasts for the present period; analysed meteorological fields are used to represent specifically each date and hour. Differences arise both from the fact that a climate model run results in a pure model output, with no influence from observations (which are useful to correct for a range of errors), and that in a "climate" set-up, simulations on a given day, month or even season cannot be related to any specific period of time (but can just be interpreted in a climatological sense). Hence, although an air quality model can be thoroughly validated in a "realistic" set-up using analysed meteorological fields, the question remains of how far its outputs can be interpreted in a "climate" set-up. For this purpose, we focus on Europe and on the current decade using three 5-yr simulations performed with the multiscale chemistry-transport model MOCAGE and use meteorological forcings either from operational meteorological analyses or from climate simulations. We investigate how statistical skill indicators compare in the different simulations, discriminating also the effects of meteorology on atmospheric fields (winds, temperature, humidity, pressure, etc.) and on the dependent emissions and deposition processes (volatile organic compound emissions, deposition velocities, etc.). Our results show in particular how differing boundary layer heights and deposition velocities affect horizontal and vertical distributions of species. When the model is driven by operational analyses, the simulation accurately reproduces the observed values of O3, NOx, SO2 and, with some bias that can be explained by the set-up, PM10. We study how the simulations driven by climate

  1. Climate forcing of an emerging pathogenic fungus across a montane multi-host community.

    Science.gov (United States)

    Clare, Frances C; Halder, Julia B; Daniel, Olivia; Bielby, Jon; Semenov, Mikhail A; Jombart, Thibaut; Loyau, Adeline; Schmeller, Dirk S; Cunningham, Andrew A; Rowcliffe, Marcus; Garner, Trenton W J; Bosch, Jaime; Fisher, Matthew C

    2016-12-05

    Changes in the timings of seasonality as a result of anthropogenic climate change are predicted to occur over the coming decades. While this is expected to have widespread impacts on the dynamics of infectious disease through environmental forcing, empirical data are lacking. Here, we investigated whether seasonality, specifically the timing of spring ice-thaw, affected susceptibility to infection by the emerging pathogenic fungus Batrachochytrium dendrobatidis (Bd) across a montane community of amphibians that are suffering declines and extirpations as a consequence of this infection. We found a robust temporal association between the timing of the spring thaw and Bd infection in two host species, where we show that an early onset of spring forced high prevalences of infection. A third highly susceptible species (the midwife toad, Alytes obstetricans) maintained a high prevalence of infection independent of time of spring thaw. Our data show that perennially overwintering midwife toad larvae may act as a year-round reservoir of infection with variation in time of spring thaw determining the extent to which infection spills over into sympatric species. We used future temperature projections based on global climate models to demonstrate that the timing of spring thaw in this region will advance markedly by the 2050s, indicating that climate change will further force the severity of infection. Our findings on the effect of annual variability on multi-host infection dynamics show that the community-level impact of fungal infectious disease on biodiversity will need to be re-evaluated in the face of climate change.This article is part of the themed issue 'Tackling emerging fungal threats to animal health, food security and ecosystem resilience'. © 2016 The Authors.

  2. Coupling Satellite and Ground-Based Instruments to Map Climate Forcing by Anthropogenic Aerosols

    Science.gov (United States)

    Charlson, Robert J.; Anderson, Theodore L.; Hostetler, Chris (Technical Monitor)

    2000-01-01

    Climate forcing by anthropogenic aerosols is a significant but highly uncertain factor in global climate change. Only satellites can offer the global coverage essential to reducing this uncertainty; however, satellite measurements must be coupled with correlative, in situ measurements both to constrain the aerosol optical properties required in satellite retrieval algorithms and to provide chemical identification of aerosol sources. This grant funded the first two years of a three-year project which seeks to develop methodologies for combining spaceborne lidar with in-situ aerosol data sets to improve estimates of direct aerosol climate forcing. Progress under this two-year grant consisted in the development and deployment of a new in-situ capability for measuring aerosol 180' backscatter and the extinction-to-backscatter ratio. This new measurement capacity allows definitive lidar/in-situ comparisons and improves our ability to interpret lidar data in terms of climatically relevant quantities such as the extinction coefficient and optical depth. Measurements were made along the coast of Washington State, in Central Illinois, over the Indian Ocean, and in the Central Pacific. Thus, this research, combined with previous measurements by others, is rapidly building toward a global data set of extinction-to-backscatter ratio for key aerosol types. Such information will be critical to interpreting lidar data from the upcoming PICASSO-CENA, or P-C, satellite mission. Another aspect of this project is to investigate innovative ways to couple the lidar-satellite signal with targeted in-situ measurements toward a direct determination of aerosol forcing. This aspect is progressing in collaboration with NASA Langley's P-C lidar simulator and radiative transfer modeling by the University of Lille, France.

  3. Environmental forcing and Southern Ocean marine predator populations: effects of climate change and variability.

    Science.gov (United States)

    Trathan, P N; Forcada, J; Murphy, E J

    2007-12-29

    The Southern Ocean is a major component within the global ocean and climate system and potentially the location where the most rapid climate change is most likely to happen, particularly in the high-latitude polar regions. In these regions, even small temperature changes can potentially lead to major environmental perturbations. Climate change is likely to be regional and may be expressed in various ways, including alterations to climate and weather patterns across a variety of time-scales that include changes to the long interdecadal background signals such as the development of the El Niño-Southern Oscillation (ENSO). Oscillating climate signals such as ENSO potentially provide a unique opportunity to explore how biological communities respond to change. This approach is based on the premise that biological responses to shorter-term sub-decadal climate variability signals are potentially the best predictor of biological responses over longer time-scales. Around the Southern Ocean, marine predator populations show periodicity in breeding performance and productivity, with relationships with the environment driven by physical forcing from the ENSO region in the Pacific. Wherever examined, these relationships are congruent with mid-trophic-level processes that are also correlated with environmental variability. The short-term changes to ecosystem structure and function observed during ENSO events herald potential long-term changes that may ensue following regional climate change. For example, in the South Atlantic, failure of Antarctic krill recruitment will inevitably foreshadow recruitment failures in a range of higher trophic-level marine predators. Where predator species are not able to accommodate by switching to other prey species, population-level changes will follow. The Southern Ocean, though oceanographically interconnected, is not a single ecosystem and different areas are dominated by different food webs. Where species occupy different positions in

  4. Varying Influence of Different Forcings on the Indo-Pacific Warm Pool Climate

    Science.gov (United States)

    Mohtadi, M.; Huang, E.; Hollstein, M.; Chen, Y.; Schefuß, E.; Rosenthal, Y.; Prange, M.; Oppo, D.; Liu, J.; Steinke, S.; Martinez-Mendez, G.; Tian, J.; Moffa-Sanchez, P.; Lückge, A.

    2017-12-01

    Proxy records of rainfall in marine archives from the eastern and western parts of the Indo-Pacific Warm Pool (IPWP) vary at precessional band and suggest a dominant role of orbital forcing by modulating monsoon rainfall and the position of the Inter Tropical Convergence Zone. Rainfall changes recorded in marine archives from the northern South China Sea reveal a more complex history. They are largely consistent with those recorded in the Chinese cave speleothems during glacial periods, but show opposite changes during interglacial peaks that coincide with strong Northern Hemisphere summer insolation maxima. During glacial periods, the establishment of massive Northern Hemisphere ice sheets and the exposure of broad continental shelves in East and Southeast Asia alter the large-scale routes and amounts of water vapor transport onto land relative to interglacials. Precipitation over China during glacials varies at precessional band and is dominated by water vapor transport from the nearby tropical and northwest Pacific, resulting in consistent changes in precipitation over large areas. In the absence of ice forcing during peak interglacials with a strong summer insolation, the low-level southerly monsoonal winds mainly of the Indian Ocean origin penetrate further landward and rainout along their path over China. Subsurface temperatures from the IPWP lack changes on glacial-interglacial timescales but follow the obliquity cycle, and suggest that obliquity-paced climate variations at mid-latitudes remotely control subsurface temperatures in the IPWP. Temperature and rainfall in the IPWP respond primarily to abrupt climate changes in the North Atlantic on millennial timescales, and to ENSO and solar forcing on interannual to decadal timescales. In summary, results from marine records reveal that the IPWP climate is sensitive to changes in spatial and temporal distribution of heat by many types of forcing, the influence of which seems to vary in time and space.

  5. Contributions of developed and developing countries to global climate forcing and surface temperature change

    International Nuclear Information System (INIS)

    Ward, D S; Mahowald, N M

    2014-01-01

    Understanding the relative contributions of individual countries to global climate change for different time periods is essential for mitigation strategies that seek to hold nations accountable for their historical emissions. Previous assessments of this kind have compared countries by their greenhouse gas emissions, but have yet to consider the full spectrum of the short-lived gases and aerosols. In this study, we use the radiative forcing of anthropogenic emissions of long-lived greenhouse gases, ozone precursors, aerosols, and from albedo changes from land cover change together with a simple climate model to evaluate country contributions to climate change. We assess the historical contribution of each country to global surface temperature change from anthropogenic forcing ( Δ T s ), future Δ T s through year 2100 given two different emissions scenarios, and the Δ T s that each country has committed to from past activities between 1850 and 2010 (committed Δ T s ). By including forcings in addition to the long-lived greenhouse gases the contribution of developed countries, particularly the United States, to Δ T s from 1850 to 2010 (58%) is increased compared to an assessment of CO 2 -equivalent emissions for the same time period (52%). Contributions to committed Δ T s evaluated at year 2100, dominated by long-lived greenhouse gas forcing, are more evenly split between developed and developing countries (55% and 45%, respectively). The portion of anthropogenic Δ T s attributable to developing countries is increasing, led by emissions from China and India, and we estimate that this will surpass the contribution from developed countries around year 2030. (paper)

  6. Timing and climate forcing of volcanic eruptions for the past 2,500 years.

    Science.gov (United States)

    Sigl, M; Winstrup, M; McConnell, J R; Welten, K C; Plunkett, G; Ludlow, F; Büntgen, U; Caffee, M; Chellman, N; Dahl-Jensen, D; Fischer, H; Kipfstuhl, S; Kostick, C; Maselli, O J; Mekhaldi, F; Mulvaney, R; Muscheler, R; Pasteris, D R; Pilcher, J R; Salzer, M; Schüpbach, S; Steffensen, J P; Vinther, B M; Woodruff, T E

    2015-07-30

    Volcanic eruptions contribute to climate variability, but quantifying these contributions has been limited by inconsistencies in the timing of atmospheric volcanic aerosol loading determined from ice cores and subsequent cooling from climate proxies such as tree rings. Here we resolve these inconsistencies and show that large eruptions in the tropics and high latitudes were primary drivers of interannual-to-decadal temperature variability in the Northern Hemisphere during the past 2,500 years. Our results are based on new records of atmospheric aerosol loading developed from high-resolution, multi-parameter measurements from an array of Greenland and Antarctic ice cores as well as distinctive age markers to constrain chronologies. Overall, cooling was proportional to the magnitude of volcanic forcing and persisted for up to ten years after some of the largest eruptive episodes. Our revised timescale more firmly implicates volcanic eruptions as catalysts in the major sixth-century pandemics, famines, and socioeconomic disruptions in Eurasia and Mesoamerica while allowing multi-millennium quantification of climate response to volcanic forcing.

  7. Carbon dioxide emissions from a septic tank soakaway in a northern maritime climate.

    Science.gov (United States)

    Somlai-Haase, Celia; Knappe, Jan; Gill, Laurence

    2017-05-15

    Here, we present the first attempt to quantify long-term and diurnal variations of CO 2 fluxes from a soakaway of an on-site wastewater treatment system serving a single house located in a northern maritime climate (Ireland). An automated soil gas flux chamber system was deployed semi-continuously over a period of 17months, recording hourly flux measurements from the soakaway (F soak ) and a control site (F control ). Soil gas fluxes expressed seasonal and diurnal variations: F soak and F control ranged from 0.43 to 100.26μmolCO 2 m -2 s -1 and 0.45 to 19.92μmolCO 2 m -2 s -1 with median fluxes of 6.86 and 5.05μmolCO 2 m -2 s -1 , respectively. While temperature, soil water content, and atmospheric pressure were identified as the most significant environmental factors correlated to the release of CO 2 from the control site, fluxes from the soakaway showed weaker correlations in regard to environmental factors. Assuming homogeneous spatial flux distributions, the soakaway emitted 15.0kgyr -1 more CO 2 into the atmosphere in total compared to a similarly sized control site. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Report of the Defense Science Board Task Force on Trends and Implications of Climate Change on National and International Security

    Science.gov (United States)

    2011-10-01

    Honduras Senegal Ethiopia Iran Rwanda Fiji Libya Pakistan Source: World Bank 2009. 99 100 52 I CHAPTER 3 101 102 103 POTENTIAL...Southern Command Perspective Mr. Rod Snider American Red Cross American Red Cross and Climate Change MG Bob Barnes Nature Conservancy The Nature ...Model Intercomparison Project CMIP5 5th Coupled Model Intercomparison Project CO2 carbon dioxide COE Center of Excellence for Disaster Management

  9. Stratospheric sulfur and its implications for radiative forcing simulated by the chemistry climate model EMAC.

    Science.gov (United States)

    Brühl, C; Lelieveld, J; Tost, H; Höpfner, M; Glatthor, N

    2015-03-16

    Multiyear simulations with the atmospheric chemistry general circulation model EMAC with a microphysical modal aerosol module at high vertical resolution demonstrate that the sulfur gases COS and SO 2 , the latter from low-latitude and midlatitude volcanic eruptions, predominantly control the formation of stratospheric aerosol. Marine dimethyl sulfide (DMS) and other SO 2 sources, including strong anthropogenic emissions in China, are found to play a minor role except in the lowermost stratosphere. Estimates of volcanic SO 2 emissions are based on satellite observations using Total Ozone Mapping Spectrometer and Ozone Monitoring Instrument for total injected mass and Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on Envisat or Stratospheric Aerosol and Gases Experiment for the spatial distribution. The 10 year SO 2 and COS data set of MIPAS is also used for model evaluation. The calculated radiative forcing of stratospheric background aerosol including sulfate from COS and small contributions by DMS oxidation, and organic aerosol from biomass burning, is about 0.07W/m 2 . For stratospheric sulfate aerosol from medium and small volcanic eruptions between 2005 and 2011 a global radiative forcing up to 0.2W/m 2 is calculated, moderating climate warming, while for the major Pinatubo eruption the simulated forcing reaches 5W/m 2 , leading to temporary climate cooling. The Pinatubo simulation demonstrates the importance of radiative feedback on dynamics, e.g., enhanced tropical upwelling, for large volcanic eruptions.

  10. Climate catastrophes

    Science.gov (United States)

    Budyko, Mikhail

    1999-05-01

    Climate catastrophes, which many times occurred in the geological past, caused the extinction of large or small populations of animals and plants. Changes in the terrestrial and marine biota caused by the catastrophic climate changes undoubtedly resulted in considerable fluctuations in global carbon cycle and atmospheric gas composition. Primarily, carbon dioxide and other greenhouse gas contents were affected. The study of these catastrophes allows a conclusion that climate system is very sensitive to relatively small changes in climate-forcing factors (transparency of the atmosphere, changes in large glaciations, etc.). It is important to take this conclusion into account while estimating the possible consequences of now occurring anthropogenic warming caused by the increase in greenhouse gas concentration in the atmosphere.

  11. 75 FR 43944 - Defense Science Board; Task Force on Trends and Implications of Climate Change for National and...

    Science.gov (United States)

    2010-07-27

    ... DEPARTMENT OF DEFENSE Office of the Secretary Defense Science Board; Task Force on Trends and Implications of Climate Change for National and International Security AGENCY: Department of Defense (DoD... and Implications of Climate Change for National and International Security will meet in closed session...

  12. 75 FR 34438 - Defense Science Board Task Force on Trends and Implications of Climate Change for National and...

    Science.gov (United States)

    2010-06-17

    ... DEPARTMENT OF DEFENSE Office of the Secretary Defense Science Board Task Force on Trends and Implications of Climate Change for National and International Security AGENCY: Department of Defense (DoD... and Implications of Climate Change for National and International Security will meet in closed session...

  13. Molecular dynamics study of combustion reactions in supercritical environment. Part 1: Carbon dioxide and water force field parameters refitting and critical isotherms of binary mixtures

    International Nuclear Information System (INIS)

    Masunov, Artem E.; Atlanov, Arseniy Alekseyevich; Vasu, Subith S.

    2016-01-01

    Oxy-fuel combustion process is expected to drastically increase the energy efficiency and enable easy carbon sequestration. In this technology the combustion products (carbon dioxide and water) are used to control the temperature and nitrogen is excluded from the combustion chamber, so that nitrogen oxide pollutants do not form. Therefore, in oxycombustion the carbon dioxide and water are present in large concentrations in their transcritical state, and may play an important role in kinetics. The computational chemistry methods may assist in understanding these effects, and Molecular Dynamics with ReaxFF force field seem to be a suitable tool for such a study. Here we investigate applicability of the ReaxFF to describe the critical phenomena in carbon dioxide and water and find that several nonbonding parameters need adjustment. We report the new parameter set, capable to reproduce the critical temperatures and pressures. Furthermore, the critical isotherms of CO 2 /H 2 O binary mixtures are computationally studied here for the first time and their critical parameters are reported.

  14. Carbon dioxide, climate and the deep ocean circulation: Carbon chemistry model

    International Nuclear Information System (INIS)

    Menawat, A.S.

    1992-01-01

    The objective of this study was to investigate the role of oceanic carbon chemistry in modulating the atmospheric levels of CO 2 . It is well known that the oceans are the primary sink of the excess carbon pumped into the atmosphere since the beginning of the industrial period. The suspended particulate and the dissolved organic matters in the deep ocean play important roles as carriers of carbon and other elements critical to the fate of CO 2 . In addition, the suspended particulate matter provides sites for oxidation-reduction reactions and microbial activities. The problem is of an intricate system with complex chemical, physical and biological processes. This report describes a methodology to describe the interconversions of different forms of the organic and inorganic nutrients, that may be incorporated in the ocean circulation models. Our approach includes the driving force behind the transfers in addition to balancing the elements. Such thermodynamic considerations of describing the imbalance in the chemical potentials is a new and unique feature of our approach

  15. Response of air-sea carbon fluxes and climate to orbital forcing changes in the Community Climate System Model

    Science.gov (United States)

    Jochum, M.; Peacock, S.; Moore, K.; Lindsay, K.

    2010-07-01

    A global general circulation model coupled to an ocean ecosystem model is used to quantify the response of carbon fluxes and climate to changes in orbital forcing. Compared to the present-day simulation, the simulation with the Earth's orbital parameters from 115,000 years ago features significantly cooler northern high latitudes but only moderately cooler southern high latitudes. This asymmetry is explained by a 30% reduction of the strength of the Atlantic Meridional Overturning Circulation that is caused by an increased Arctic sea ice export and a resulting freshening of the North Atlantic. The strong northern high-latitude cooling and the direct insolation induced tropical warming lead to global shifts in precipitation and winds to the order of 10%-20%. These climate shifts lead to regional differences in air-sea carbon fluxes of the same order. However, the differences in global net air-sea carbon fluxes are small, which is due to several effects, two of which stand out: first, colder sea surface temperature leads to a more effective solubility pump but also to increased sea ice concentration which blocks air-sea exchange, and second, the weakening of Southern Ocean winds that is predicted by some idealized studies occurs only in part of the basin, and is compensated by stronger winds in other parts.

  16. Force majeure: Will climate change affect our ability to attain Good Environmental Status for marine biodiversity?

    Science.gov (United States)

    Elliott, Michael; Borja, Ángel; McQuatters-Gollop, Abigail; Mazik, Krysia; Birchenough, Silvana; Andersen, Jesper H; Painting, Suzanne; Peck, Myron

    2015-06-15

    The EU Marine Strategy Framework Directive (MSFD) requires that Good Environmental Status (GEnS), is achieved for European seas by 2020. These may deviate from GEnS, its 11 Descriptors, targets and baselines, due to endogenic managed pressures (from activities within an area) and externally due to exogenic unmanaged pressures (e.g. climate change). Conceptual models detail the likely or perceived changes expected on marine biodiversity and GEnS Descriptors in the light of climate change. We emphasise that marine management has to accommodate 'shifting baselines' caused by climate change particularly during GEnS monitoring, assessment and management and 'unbounded boundaries' given the migration and dispersal of highly-mobile species. We suggest climate change may prevent GEnS being met, but Member States may rebut legal challenges by claiming that this is outside its control, force majeure or due to 'natural causes' (Article 14 of the MSFD). The analysis is relevant to management of other global seas. Copyright © 2015 Elsevier Ltd. All rights reserved.

  17. Northern Hemisphere Winter Climate Response to Greenhouse Gas, Ozone, Solar and Volcanic Forcing

    Science.gov (United States)

    Shindell, Drew T.; Schmidt, Gavin A.; Miller, Ron L.; Rind, David; Hansen, James E. (Technical Monitor)

    2001-01-01

    The Goddard Institute for Space Studies (GISS) climate/middle atmosphere model has been used to study the impacts of increasing greenhouse gases, polar ozone depletion, volcanic eruptions, and solar cycle variability. We focus on the projection of the induced responses onto Northern Hemisphere winter surface climate. Changes in the model's surface climate take place largely through enhancement of existing variability patterns, with greenhouse gases, polar ozone depletion and volcanic eruptions primarily affecting the Arctic Oscillation (AO) pattern. Perturbations descend from the stratosphere to the surface in the model by altering the propagation of planetary waves coming up from the surface, in accord with observational evidence. Models lacking realistic stratospheric dynamics fail to capture these wave flux changes. The results support the conclusion that the stratosphere plays a crucial role in recent AO trends. We show that in our climate model, while ozone depletion has a significant effect, greenhouse gas forcing is the only one capable of causing the large, sustained increase in the AO observed over recent decades. This suggests that the AO trend, and a concurrent strengthening of the stratospheric vortex over the Arctic, are very likely anthropogenic in origin.

  18. Climate extremes, land-climate feedbacks and land-use forcing at 1.5°C.

    Science.gov (United States)

    Seneviratne, Sonia I; Wartenburger, Richard; Guillod, Benoit P; Hirsch, Annette L; Vogel, Martha M; Brovkin, Victor; van Vuuren, Detlef P; Schaller, Nathalie; Boysen, Lena; Calvin, Katherine V; Doelman, Jonathan; Greve, Peter; Havlik, Petr; Humpenöder, Florian; Krisztin, Tamas; Mitchell, Daniel; Popp, Alexander; Riahi, Keywan; Rogelj, Joeri; Schleussner, Carl-Friedrich; Sillmann, Jana; Stehfest, Elke

    2018-05-13

    This article investigates projected changes in temperature and water cycle extremes at 1.5°C of global warming, and highlights the role of land processes and land-use changes (LUCs) for these projections. We provide new comparisons of changes in climate at 1.5°C versus 2°C based on empirical sampling analyses of transient simulations versus simulations from the 'Half a degree Additional warming, Prognosis and Projected Impacts' (HAPPI) multi-model experiment. The two approaches yield similar overall results regarding changes in climate extremes on land, and reveal a substantial difference in the occurrence of regional extremes at 1.5°C versus 2°C. Land processes mediated through soil moisture feedbacks and land-use forcing play a major role for projected changes in extremes at 1.5°C in most mid-latitude regions, including densely populated areas in North America, Europe and Asia. This has important implications for low-emissions scenarios derived from integrated assessment models (IAMs), which include major LUCs in ambitious mitigation pathways (e.g. associated with increased bioenergy use), but are also shown to differ in the simulated LUC patterns. Biogeophysical effects from LUCs are not considered in the development of IAM scenarios, but play an important role for projected regional changes in climate extremes, and are thus of high relevance for sustainable development pathways.This article is part of the theme issue 'The Paris Agreement: understanding the physical and social challenges for a warming world of 1.5°C above pre-industrial levels'. © 2018 The Authors.

  19. Climate extremes, land–climate feedbacks and land-use forcing at 1.5°C

    Science.gov (United States)

    Wartenburger, Richard; Guillod, Benoit P.; Hirsch, Annette L.; Vogel, Martha M.; Brovkin, Victor; van Vuuren, Detlef P.; Schaller, Nathalie; Boysen, Lena; Calvin, Katherine V.; Doelman, Jonathan; Greve, Peter; Havlik, Petr; Humpenöder, Florian; Krisztin, Tamas; Mitchell, Daniel; Popp, Alexander; Riahi, Keywan; Rogelj, Joeri; Schleussner, Carl-Friedrich; Sillmann, Jana; Stehfest, Elke

    2018-01-01

    This article investigates projected changes in temperature and water cycle extremes at 1.5°C of global warming, and highlights the role of land processes and land-use changes (LUCs) for these projections. We provide new comparisons of changes in climate at 1.5°C versus 2°C based on empirical sampling analyses of transient simulations versus simulations from the ‘Half a degree Additional warming, Prognosis and Projected Impacts’ (HAPPI) multi-model experiment. The two approaches yield similar overall results regarding changes in climate extremes on land, and reveal a substantial difference in the occurrence of regional extremes at 1.5°C versus 2°C. Land processes mediated through soil moisture feedbacks and land-use forcing play a major role for projected changes in extremes at 1.5°C in most mid-latitude regions, including densely populated areas in North America, Europe and Asia. This has important implications for low-emissions scenarios derived from integrated assessment models (IAMs), which include major LUCs in ambitious mitigation pathways (e.g. associated with increased bioenergy use), but are also shown to differ in the simulated LUC patterns. Biogeophysical effects from LUCs are not considered in the development of IAM scenarios, but play an important role for projected regional changes in climate extremes, and are thus of high relevance for sustainable development pathways. This article is part of the theme issue ‘The Paris Agreement: understanding the physical and social challenges for a warming world of 1.5°C above pre-industrial levels'. PMID:29610382

  20. Climate extremes, land-climate feedbacks and land-use forcing at 1.5°C

    Science.gov (United States)

    Seneviratne, Sonia I.; Wartenburger, Richard; Guillod, Benoit P.; Hirsch, Annette L.; Vogel, Martha M.; Brovkin, Victor; van Vuuren, Detlef P.; Schaller, Nathalie; Boysen, Lena; Calvin, Katherine V.; Doelman, Jonathan; Greve, Peter; Havlik, Petr; Humpenöder, Florian; Krisztin, Tamas; Mitchell, Daniel; Popp, Alexander; Riahi, Keywan; Rogelj, Joeri; Schleussner, Carl-Friedrich; Sillmann, Jana; Stehfest, Elke

    2018-05-01

    This article investigates projected changes in temperature and water cycle extremes at 1.5°C of global warming, and highlights the role of land processes and land-use changes (LUCs) for these projections. We provide new comparisons of changes in climate at 1.5°C versus 2°C based on empirical sampling analyses of transient simulations versus simulations from the `Half a degree Additional warming, Prognosis and Projected Impacts' (HAPPI) multi-model experiment. The two approaches yield similar overall results regarding changes in climate extremes on land, and reveal a substantial difference in the occurrence of regional extremes at 1.5°C versus 2°C. Land processes mediated through soil moisture feedbacks and land-use forcing play a major role for projected changes in extremes at 1.5°C in most mid-latitude regions, including densely populated areas in North America, Europe and Asia. This has important implications for low-emissions scenarios derived from integrated assessment models (IAMs), which include major LUCs in ambitious mitigation pathways (e.g. associated with increased bioenergy use), but are also shown to differ in the simulated LUC patterns. Biogeophysical effects from LUCs are not considered in the development of IAM scenarios, but play an important role for projected regional changes in climate extremes, and are thus of high relevance for sustainable development pathways. This article is part of the theme issue `The Paris Agreement: understanding the physical and social challenges for a warming world of 1.5°C above pre-industrial levels'.

  1. A double-integration hypothesis to explain ocean ecosystem response to climate forcing

    Science.gov (United States)

    Di Lorenzo, Emanuele; Ohman, Mark D.

    2013-01-01

    Long-term time series of marine ecological indicators often are characterized by large-amplitude state transitions that can persist for decades. Understanding the significance of these variations depends critically on the underlying hypotheses characterizing expected natural variability. Using a linear autoregressive model in combination with long-term zooplankton observations off the California coast, we show that cumulative integrations of white-noise atmospheric forcing can generate marine population responses that are characterized by strong transitions and prolonged apparent state changes. This model provides a baseline hypothesis for explaining ecosystem variability and for interpreting the significance of abrupt responses and climate change signatures in marine ecosystems. PMID:23341628

  2. 20th-century industrial black carbon emissions altered Arctic climate forcing.

    Science.gov (United States)

    McConnell, Joseph R; Edwards, Ross; Kok, Gregory L; Flanner, Mark G; Zender, Charles S; Saltzman, Eric S; Banta, J Ryan; Pasteris, Daniel R; Carter, Megan M; Kahl, Jonathan D W

    2007-09-07

    Black carbon (BC) from biomass and fossil fuel combustion alters chemical and physical properties of the atmosphere and snow albedo, yet little is known about its emission or deposition histories. Measurements of BC, vanillic acid, and non-sea-salt sulfur in ice cores indicate that sources and concentrations of BC in Greenland precipitation varied greatly since 1788 as a result of boreal forest fires and industrial activities. Beginning about 1850, industrial emissions resulted in a sevenfold increase in ice-core BC concentrations, with most change occurring in winter. BC concentrations after about 1951 were lower but increasing. At its maximum from 1906 to 1910, estimated surface climate forcing in early summer from BC in Arctic snow was about 3 watts per square meter, which is eight times the typical preindustrial forcing value.

  3. Carbon dioxide and climate impulse response functions for the computation of greenhouse gas metrics: a multi-model analysis

    Directory of Open Access Journals (Sweden)

    F. Joos

    2013-03-01

    Full Text Available The responses of carbon dioxide (CO2 and other climate variables to an emission pulse of CO2 into the atmosphere are often used to compute the Global Warming Potential (GWP and Global Temperature change Potential (GTP, to characterize the response timescales of Earth System models, and to build reduced-form models. In this carbon cycle-climate model intercomparison project, which spans the full model hierarchy, we quantify responses to emission pulses of different magnitudes injected under different conditions. The CO2 response shows the known rapid decline in the first few decades followed by a millennium-scale tail. For a 100 Gt-C emission pulse added to a constant CO2 concentration of 389 ppm, 25 ± 9% is still found in the atmosphere after 1000 yr; the ocean has absorbed 59 ± 12% and the land the remainder (16 ± 14%. The response in global mean surface air temperature is an increase by 0.20 ± 0.12 °C within the first twenty years; thereafter and until year 1000, temperature decreases only slightly, whereas ocean heat content and sea level continue to rise. Our best estimate for the Absolute Global Warming Potential, given by the time-integrated response in CO2 at year 100 multiplied by its radiative efficiency, is 92.5 × 10−15 yr W m−2 per kg-CO2. This value very likely (5 to 95% confidence lies within the range of (68 to 117 × 10−15 yr W m−2 per kg-CO2. Estimates for time-integrated response in CO2 published in the IPCC First, Second, and Fourth Assessment and our multi-model best estimate all agree within 15% during the first 100 yr. The integrated CO2 response, normalized by the pulse size, is lower for pre-industrial conditions, compared to present day, and lower for smaller pulses than larger pulses. In contrast, the response in temperature, sea level and ocean heat content is less sensitive to these choices. Although, choices in pulse size, background concentration, and model lead to uncertainties, the most important and

  4. Future local and remote influences on Mediterranean ozone air quality and climate forcing

    Science.gov (United States)

    Arnold, Steve; Martin, Maria Val; Emmons, Louisa; Rap, Alex; Heald, Colette; Lamarque, Jean-Francois; Tilmes, Simone

    2013-04-01

    The Mediterranean region is expected to display large increases in population over the coming decades, and to exhibit strong sensitivity to projected climate change, with increasing frequency of extreme summer temperatures and decreases in precipitation. Understanding of how these changes will affect atmospheric composition in the region is limited. The eastern Mediterranean basin has been shown to exhibit a pronounced summertime local maximum in tropospheric ozone, which impacts both local air quality and the atmospheric radiation balance. In summer, the region is subject to import of pollution from Northern Europe in the boundary layer and lower troposphere, from North American sources in the large-scale westerly flow of the free mid and upper-troposphere, as well as import of pollution lofted in the Asian monsoon and carried west to the eastern Mediterranean in anticyclonic flow in the upper troposphere over north Africa. In addition, interactions with the land-surface through biogenic emission sources and dry deposition play important roles in the Mediterranean ozone budget. Here we use the NCAR Community Earth System Model (CESM) to investigate how tropospheric ozone in the Mediterranean region responds to climate, land surface and global emissions changes between present day and 2050. We simulate climate and atmospheric composition for the year 2050, based on greenhouse gas abundances, trace gas and aerosol emissions and land cover and use from two representative concentration pathway (RCP) scenarios (RCP4.5 & RCP8.5), designed for use by the Coupled Model Intercomparison Project Phase 5(CMIP5) experiments in support of the IPCC. By comparing these simulations with a present-day scenario, we investigate the effects of predicted changes in climate and emissions on air quality and climate forcing over the Mediterranean region. The simulations suggest decreases in boundary layer ozone and sulfate aerosol throughout the tropospheric column over the Mediterranean

  5. Silver birch and climate change: variable growth and carbon allocation responses to elevated concentrations of carbon dioxide and ozone

    International Nuclear Information System (INIS)

    Riikonen, J.; Holopainen, T.; Oksanen, E.; Lindsberg, M-M.; Lappi, J.; Peltonen, P.; Vapaavuori, E.

    2004-01-01

    The effects of elevated concentrations of carbon dioxide and ozone were studied on growth, biomass allocation and leaf area of field-grown ozone-tolerant (Clone 4) and ozone-sensitive (Clone 80) European silver birch trees. Seven-year old trees of both types were exposed for three years to outside and chamber control, (1) twice ambient ozone, (2) twice ambient carbon dioxide, and (3) twice ambient carbon dioxide and twice ambient ozone. No effect on biomass allocation was observed when results of the two clones were analyzed together. Total leaf area showed an increase, and leaf abscission appeared delayed in response to elevated carbon dioxide. Elevated ozone caused the dry mass of roots, branches and mean leaf size to decrease, and autumnal leaf abscission occurred earlier than usual in both clones. In general. the effects of elevated ozone were small, however, the interaction between elevated carbon dioxide and elevated oxygen were significant. When results from the two clones were analyzed separately, stem diameter, volume growth and total biomass of Clone 80 increased when exposed to elevated concentrations of carbon dioxide; elevated concentrations of ozone appeared to have no effect. In Clone 4 elevated ozone caused significant decrease in root and branch biomass, but the effects of elevated carbon dioxide were minimal. Responses to elevated ozone exposure were observed only under ambient carbon dioxide conditions. This response is believed to reflect the greater quantity of carbohydrates available for detoxification and repair under elevated carbon dioxide conditions. Alternatively, the response may be due to decreased stomatal conductance, thus decreased ozone uptake under elevated carbon dioxide conditions. 45 refs., 6 tabs., 4 figs

  6. A statistical mechanical approach for the computation of the climatic response to general forcings

    Directory of Open Access Journals (Sweden)

    V. Lucarini

    2011-01-01

    Full Text Available The climate belongs to the class of non-equilibrium forced and dissipative systems, for which most results of quasi-equilibrium statistical mechanics, including the fluctuation-dissipation theorem, do not apply. In this paper we show for the first time how the Ruelle linear response theory, developed for studying rigorously the impact of perturbations on general observables of non-equilibrium statistical mechanical systems, can be applied with great success to analyze the climatic response to general forcings. The crucial value of the Ruelle theory lies in the fact that it allows to compute the response of the system in terms of expectation values of explicit and computable functions of the phase space averaged over the invariant measure of the unperturbed state. We choose as test bed a classical version of the Lorenz 96 model, which, in spite of its simplicity, has a well-recognized prototypical value as it is a spatially extended one-dimensional model and presents the basic ingredients, such as dissipation, advection and the presence of an external forcing, of the actual atmosphere. We recapitulate the main aspects of the general response theory and propose some new general results. We then analyze the frequency dependence of the response of both local and global observables to perturbations having localized as well as global spatial patterns. We derive analytically several properties of the corresponding susceptibilities, such as asymptotic behavior, validity of Kramers-Kronig relations, and sum rules, whose main ingredient is the causality principle. We show that all the coefficients of the leading asymptotic expansions as well as the integral constraints can be written as linear function of parameters that describe the unperturbed properties of the system, such as its average energy. Some newly obtained empirical closure equations for such parameters allow to define such properties as an explicit function of the unperturbed forcing

  7. Homogeneous nucleation in supersaturated vapors of methane, ethane, and carbon dioxide predicted by brute force molecular dynamics.

    Science.gov (United States)

    Horsch, Martin; Vrabec, Jadran; Bernreuther, Martin; Grottel, Sebastian; Reina, Guido; Wix, Andrea; Schaber, Karlheinz; Hasse, Hans

    2008-04-28

    Molecular dynamics (MD) simulation is applied to the condensation process of supersaturated vapors of methane, ethane, and carbon dioxide. Simulations of systems with up to a 10(6) particles were conducted with a massively parallel MD program. This leads to reliable statistics and makes nucleation rates down to the order of 10(30) m(-3) s(-1) accessible to the direct simulation approach. Simulation results are compared to the classical nucleation theory (CNT) as well as the modification of Laaksonen, Ford, and Kulmala (LFK) which introduces a size dependence of the specific surface energy. CNT describes the nucleation of ethane and carbon dioxide excellently over the entire studied temperature range, whereas LFK provides a better approach to methane at low temperatures.

  8. Synchronous fire activity in the tropical high Andes: an indication of regional climate forcing.

    Science.gov (United States)

    Román-Cuesta, R M; Carmona-Moreno, C; Lizcano, G; New, M; Silman, M; Knoke, T; Malhi, Y; Oliveras, I; Asbjornsen, H; Vuille, M

    2014-06-01

    Global climate models suggest enhanced warming of the tropical mid and upper troposphere, with larger temperature rise rates at higher elevations. Changes in fire activity are amongst the most significant ecological consequences of rising temperatures and changing hydrological properties in mountainous ecosystems, and there is a global evidence of increased fire activity with elevation. Whilst fire research has become popular in the tropical lowlands, much less is known of the tropical high Andean region (>2000 masl, from Colombia to Bolivia). This study examines fire trends in the high Andes for three ecosystems, the Puna, the Paramo and the Yungas, for the period 1982-2006. We pose three questions: (i) is there an increased fire response with elevation? (ii) does the El Niño- Southern Oscillation control fire activity in this region? (iii) are the observed fire trends human driven (e.g., human practices and their effects on fuel build-up) or climate driven? We did not find evidence of increased fire activity with elevation but, instead, a quasicyclic and synchronous fire response in Ecuador, Peru and Bolivia, suggesting the influence of high-frequency climate forcing on fire responses on a subcontinental scale, in the high Andes. ENSO variability did not show a significant relation to fire activity for these three countries, partly because ENSO variability did not significantly relate to precipitation extremes, although it strongly did to temperature extremes. Whilst ENSO did not individually lead the observed regional fire trends, our results suggest a climate influence on fire activity, mainly through a sawtooth pattern of precipitation (increased rainfall before fire-peak seasons (t-1) followed by drought spells and unusual low temperatures (t0), which is particularly common where fire is carried by low fuel loads (e.g., grasslands and fine fuel). This climatic sawtooth appeared as the main driver of fire trends, above local human influences and fuel build

  9. Insight to forcing of late Quaternary climate change from aeolian dust archives in eastern Australia

    Science.gov (United States)

    McGowan, H. A.; Marx, S.; Soderholm, J.; Denholm, J.; Petherick, L.

    2010-12-01

    The Australian continent is the largest source of dust in the Southern Hemisphere. Historical dust emissions records display inter-annual variability in response to the El Niño Southern Oscillation (ENSO) phenomenon and inter-decadal variability which has been linked to the Pacific Decadal Oscillation (PDO). These reflect change in hydrometeorology of the continents two major dust source regions, the Murray-Darling Basin and the Lake Eyre Basin. The historical records do not allow longer term variability of ENSO and the PDO and their influence on Australia to be quantified. Importantly, sub-Milankovitch centennial to multi-millennial scale climate cycles and their impacts are not represented in the historical records. In this paper we present summary results from the analysis of two aeolain dust records spanning 7 ka and 45 ka. These were developed from ombrotrophic mire and lacustrine sediment cores collected from the Australian Alps and southeast Queensland. Both sites are located in the southeast Australian dust transport pathway and provide rare insight to forcings of climate variability and its impacts on eastern Australia through the late Quaternary. Age controls for the cores were established using 14C and 210Pb dating [McGowan et al. 2008, 2010]. The cores were sliced into 2 to 5 mm segments with a sub-sample of each segment combusted at 450°C for 12 hrs to destroy organic material and allow recovery of mineral dust. Geochemical fingerprinting of the global climate variability and the impact of forcings originating from the North Hemisphere. These results highlight the potential for adverse impacts on the climate of Australia by disturbance to North Atlantic Ocean circulation. References Marx, S. K., et al. 2005: Provenance of long travelled dust determined with ultra trace element composition: A pilot study with samples from New Zealand glaciers. Earth Surf. Processes Landforms, 30, 699-716. McGowan, H.A., et al. 2008: An ultra-high resolution record of

  10. The influence of atmospheric grid resolution in a climate model-forced ice sheet simulation

    Science.gov (United States)

    Lofverstrom, Marcus; Liakka, Johan

    2018-04-01

    Coupled climate-ice sheet simulations have been growing in popularity in recent years. Experiments of this type are however challenging as ice sheets evolve over multi-millennial timescales, which is beyond the practical integration limit of most Earth system models. A common method to increase model throughput is to trade resolution for computational efficiency (compromise accuracy for speed). Here we analyze how the resolution of an atmospheric general circulation model (AGCM) influences the simulation quality in a stand-alone ice sheet model. Four identical AGCM simulations of the Last Glacial Maximum (LGM) were run at different horizontal resolutions: T85 (1.4°), T42 (2.8°), T31 (3.8°), and T21 (5.6°). These simulations were subsequently used as forcing of an ice sheet model. While the T85 climate forcing reproduces the LGM ice sheets to a high accuracy, the intermediate resolution cases (T42 and T31) fail to build the Eurasian ice sheet. The T21 case fails in both Eurasia and North America. Sensitivity experiments using different surface mass balance parameterizations improve the simulations of the Eurasian ice sheet in the T42 case, but the compromise is a substantial ice buildup in Siberia. The T31 and T21 cases do not improve in the same way in Eurasia, though the latter simulates the continent-wide Laurentide ice sheet in North America. The difficulty to reproduce the LGM ice sheets in the T21 case is in broad agreement with previous studies using low-resolution atmospheric models, and is caused by a substantial deterioration of the model climate between the T31 and T21 resolutions. It is speculated that this deficiency may demonstrate a fundamental problem with using low-resolution atmospheric models in these types of experiments.

  11. Does Carbon Dioxide Predict Temperature?

    OpenAIRE

    Mytty, Tuukka

    2013-01-01

    Does carbon dioxide predict temperature? No it does not, in the time period of 1880-2004 with the carbon dioxide and temperature data used in this thesis. According to the Inter Governmental Panel on Climate Change(IPCC) carbon dioxide is the most important factor in raising the global temperature. Therefore, it is reasonable to assume that carbon dioxide truly predicts temperature. Because this paper uses observational data it has to be kept in mind that no causality interpretation can be ma...

  12. Framing Climate Goals in Terms of Cumulative CO2-Forcing-Equivalent Emissions

    Science.gov (United States)

    Jenkins, S.; Millar, R. J.; Leach, N.; Allen, M. R.

    2018-03-01

    The relationship between cumulative CO2 emissions and CO2-induced warming is determined by the Transient Climate Response to Emissions (TCRE), but total anthropogenic warming also depends on non-CO2 forcing, complicating the interpretation of emissions budgets based on CO2 alone. An alternative is to frame emissions budgets in terms of CO2-forcing-equivalent (CO2-fe) emissions—the CO2 emissions that would yield a given total anthropogenic radiative forcing pathway. Unlike conventional "CO2-equivalent" emissions, these are directly related to warming by the TCRE and need to fall to zero to stabilize warming: hence, CO2-fe emissions generalize the concept of a cumulative carbon budget to multigas scenarios. Cumulative CO2-fe emissions from 1870 to 2015 inclusive are found to be 2,900 ± 600 GtCO2-fe, increasing at a rate of 67 ± 9.5 GtCO2-fe/yr. A TCRE range of 0.8-2.5°C per 1,000 GtC implies a total budget for 0.6°C of additional warming above the present decade of 880-2,750 GtCO2-fe, with 1,290 GtCO2-fe implied by the Coupled Model Intercomparison Project Phase 5 median response, corresponding to 19 years' CO2-fe emissions at the current rate.

  13. The vertical distribution of climate forcings and feedbacks from the surface to top of atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Previdi, Michael [Columbia University, Lamont-Doherty Earth Observatory, Palisades, NY (United States); Liepert, Beate G. [NorthWest Research Associates, Redmond, WA (United States)

    2012-08-15

    The radiative forcings and feedbacks that determine Earth's climate sensitivity are typically defined at the top-of-atmosphere (TOA) or tropopause, yet climate sensitivity itself refers to a change in temperature at the surface. In this paper, we describe how TOA radiative perturbations translate into surface temperature changes. It is shown using first principles that radiation changes at the TOA can be equated with the change in energy stored by the oceans and land surface. This ocean and land heat uptake in turn involves an adjustment of the surface radiative and non-radiative energy fluxes, with the latter being comprised of the turbulent exchange of latent and sensible heat between the surface and atmosphere. We employ the radiative kernel technique to decompose TOA radiative feedbacks in the IPCC Fourth Assessment Report climate models into components associated with changes in radiative heating of the atmosphere and of the surface. (We consider the equilibrium response of atmosphere-mixed layer ocean models subjected to an instantaneous doubling of atmospheric CO{sub 2}). It is shown that most feedbacks, i.e., the temperature, water vapor and cloud feedbacks, (as well as CO{sub 2} forcing) affect primarily the turbulent energy exchange at the surface rather than the radiative energy exchange. Specifically, the temperature feedback increases the surface turbulent (radiative) energy loss by 2.87 W m{sup -2} K{sup -1} (0.60 W m{sup -2} K{sup -1}) in the multimodel mean; the water vapor feedback decreases the surface turbulent energy loss by 1.07 W m{sup -2} K{sup -1} and increases the surface radiative heating by 0.89 W m{sup -2} K{sup -1}; and the cloud feedback decreases both the turbulent energy loss and the radiative heating at the surface by 0.43 and 0.24 W m{sup -2} K{sup -1}, respectively. Since changes to the surface turbulent energy exchange are dominated in the global mean sense by changes in surface evaporation, these results serve to highlight

  14. Probabilistic estimates of 1.5-degree carbon budgets based on uncertainty in transient climate response and aerosol forcing

    Science.gov (United States)

    Partanen, A. I.; Mengis, N.; Jalbert, J.; Matthews, D.

    2017-12-01

    Nations agreed to limit the increase in global mean surface temperature relative to the preindustrial era below 2 degrees Celsius and pursue efforts to a more ambitious goal of 1.5 degrees Celsius. To achieve these goals, it is necessary to assess the amount of cumulative carbon emissions compatible with these temperature targets, i.e. so called carbon budgets. In this work, we use the intermediate complexity University of Victoria Earth System Climate Model (UVic ESCM) to assess how uncertainty in aerosol forcing and transient climate response transfers to uncertainty in future carbon budgets for burning fossil fuels. We create a perturbed parameter ensemble of model simulations by scaling aerosol forcing and transient climate response, and assess the likelihood of each simulation by comparing the simulated historical cumulative carbon emissions, CO2 concentration and radiative balance to observations. By weighting the results of each simulation with the likelihood of the simulation, the preliminary results give a carbon budget of 48 Pg C to reach 1.5 degree Celsius temperature increase. The small weighted mean is due to large fraction of simulations with strong aerosol forcing and transient climate response giving negative carbon budgets for this time period. The probability of the carbon budget being over 100 Pg C was 38% and 23% for over 200 Pg carbon budget. The carbon budgets after temperature stabilization at 1.5 degrees are even smaller with a weighted mean of -100 Pg C until the year 2200. The main reason for the negative carbon budgets after temperature stabilization is an assumed strong decrease in aerosol forcing in the 21st century. Conversely, simulations with weak aerosol forcing and transient climate response give positive carbon budgets. Our results highlight both the importance of reducing uncertainty in aerosol forcing and transient climate response, and of taking the non-CO2 forcers into account when estimating carbon budgets.

  15. Differential and enhanced response to climate forcing in diarrheal disease due to rotavirus across a megacity of the developing world.

    Science.gov (United States)

    Martinez, Pamela P; King, Aaron A; Yunus, Mohammad; Faruque, A S G; Pascual, Mercedes

    2016-04-12

    The role of climate forcing in the population dynamics of infectious diseases has typically been revealed via retrospective analyses of incidence records aggregated across space and, in particular, over whole cities. Here, we focus on the transmission dynamics of rotavirus, the main diarrheal disease in infants and young children, within the megacity of Dhaka, Bangladesh. We identify two zones, the densely urbanized core and the more rural periphery, that respond differentially to flooding. Moreover, disease seasonality differs substantially between these regions, spanning variation comparable to the variation from tropical to temperate regions. By combining process-based models with an extensive disease surveillance record, we show that the response to climate forcing is mainly seasonal in the core, where a more endemic transmission resulting from an asymptomatic reservoir facilitates the response to the monsoons. The force of infection in this monsoon peak can be an order of magnitude larger than the force of infection in the more epidemic periphery, which exhibits little or no postmonsoon outbreak in a pattern typical of nearby rural areas. A typically smaller peak during the monsoon season nevertheless shows sensitivity to interannual variability in flooding. High human density in the core is one explanation for enhanced transmission during troughs and an associated seasonal monsoon response in this diarrheal disease, which unlike cholera, has not been widely viewed as climate-sensitive. Spatial demographic, socioeconomic, and environmental heterogeneity can create reservoirs of infection and enhance the sensitivity of disease systems to climate forcing, especially in the populated cities of the developing world.

  16. Climatic driving forces in inter-annual variation of global FPAR

    Science.gov (United States)

    Peng, Dailiang; Liu, Liangyun; Yang, Xiaohua; Zhou, Bin

    2012-09-01

    Fraction of Absorbed Photosynthetically Active Radiation (FPAR) characterizes vegetation canopy functioning and its energy absorption capacity. In this paper, we focus on climatic driving forces in inter-annual variation of global FPAR from 1982 to 2006 by Global Historical Climatology Network (GHCN-Monthly) data. Using FPAR-Simple Ratio Vegetation Index (SR) relationship, Advanced Very High Resolution Radiometer (AVHRR) Global Inventory Modeling and Mapping Studies (GIMMS) Normalized Difference Vegetation Index (NDVI) was used to estimate FPAR at the global scale. The correlation between inter-annual variation of FPAR and temperature, precipitation derived from GHCN-Monthly was examined, during the periods of March-May (MAM), June-August (JJA), September-November (SON), and December-February (DJF) over from 1982 to 2006. The analysis of climatic influence on global FPAR revealed the significant correlation with temperature and precipitation in some meteorological stations area, and a more significant correlation with precipitation was found than which with temperature. Some stations in the regions between 30° N and 60° N and around 30° S in South America, where the annual FPAR variation showed a significant positive correlation with temperature (P forest of Africa and Amazon during the dry season of JJA and SON.

  17. Multi-level emulation of complex climate model responses to boundary forcing data

    Science.gov (United States)

    Tran, Giang T.; Oliver, Kevin I. C.; Holden, Philip B.; Edwards, Neil R.; Sóbester, András; Challenor, Peter

    2018-04-01

    Climate model components involve both high-dimensional input and output fields. It is desirable to efficiently generate spatio-temporal outputs of these models for applications in integrated assessment modelling or to assess the statistical relationship between such sets of inputs and outputs, for example, uncertainty analysis. However, the need for efficiency often compromises the fidelity of output through the use of low complexity models. Here, we develop a technique which combines statistical emulation with a dimensionality reduction technique to emulate a wide range of outputs from an atmospheric general circulation model, PLASIM, as functions of the boundary forcing prescribed by the ocean component of a lower complexity climate model, GENIE-1. Although accurate and detailed spatial information on atmospheric variables such as precipitation and wind speed is well beyond the capability of GENIE-1's energy-moisture balance model of the atmosphere, this study demonstrates that the output of this model is useful in predicting PLASIM's spatio-temporal fields through multi-level emulation. Meaningful information from the fast model, GENIE-1 was extracted by utilising the correlation between variables of the same type in the two models and between variables of different types in PLASIM. We present here the construction and validation of several PLASIM variable emulators and discuss their potential use in developing a hybrid model with statistical components.

  18. Future climate forcing potentially without precedent in the last 420 million years.

    Science.gov (United States)

    Foster, Gavin L; Royer, Dana L; Lunt, Daniel J

    2017-04-04

    The evolution of Earth's climate on geological timescales is largely driven by variations in the magnitude of total solar irradiance (TSI) and changes in the greenhouse gas content of the atmosphere. Here we show that the slow ∼50 Wm -2 increase in TSI over the last ∼420 million years (an increase of ∼9 Wm -2 of radiative forcing) was almost completely negated by a long-term decline in atmospheric CO 2 . This was likely due to the silicate weathering-negative feedback and the expansion of land plants that together ensured Earth's long-term habitability. Humanity's fossil-fuel use, if unabated, risks taking us, by the middle of the twenty-first century, to values of CO 2 not seen since the early Eocene (50 million years ago). If CO 2 continues to rise further into the twenty-third century, then the associated large increase in radiative forcing, and how the Earth system would respond, would likely be without geological precedent in the last half a billion years.

  19. Impact of evolving greenhouse gas forcing on the warming signal in regional climate model experiments.

    Science.gov (United States)

    Jerez, S; López-Romero, J M; Turco, M; Jiménez-Guerrero, P; Vautard, R; Montávez, J P

    2018-04-03

    Variations in the atmospheric concentrations of greenhouse gases (GHG) may not be included as external forcing when running regional climate models (RCMs); at least, this is a non-regulated, non-documented practice. Here we investigate the so far unexplored impact of considering the rising evolution of the CO 2 , CH 4 , and N 2 O atmospheric concentrations on near-surface air temperature (TAS) trends, for both the recent past and the near future, as simulated by a state-of-the-art RCM over Europe. The results show that the TAS trends are significantly affected by 1-2 K century -1 , which under 1.5 °C global warming translates into a non-negligible impact of up to 1 K in the regional projections of TAS, similarly affecting projections for maximum and minimum temperatures. In some cases, these differences involve a doubling signal, laying further claim to careful reconsideration of the RCM setups with regard to the inclusion of GHG concentrations as an evolving external forcing which, for the sake of research reproducibility and reliability, should be clearly documented in the literature.

  20. Constraining Carbonaceous Aerosol Climate Forcing by Bridging Laboratory, Field and Modeling Studies

    Science.gov (United States)

    Dubey, M. K.; Aiken, A. C.; Liu, S.; Saleh, R.; Cappa, C. D.; Williams, L. R.; Donahue, N. M.; Gorkowski, K.; Ng, N. L.; Mazzoleni, C.; China, S.; Sharma, N.; Yokelson, R. J.; Allan, J. D.; Liu, D.

    2014-12-01

    Biomass and fossil fuel combustion emits black (BC) and brown carbon (BrC) aerosols that absorb sunlight to warm climate and organic carbon (OC) aerosols that scatter sunlight to cool climate. The net forcing depends strongly on the composition, mixing state and transformations of these carbonaceous aerosols. Complexities from large variability of fuel types, combustion conditions and aging processes have confounded their treatment in models. We analyse recent laboratory and field measurements to uncover fundamental mechanism that control the chemical, optical and microphysical properties of carbonaceous aerosols that are elaborated below: Wavelength dependence of absorption and the single scattering albedo (ω) of fresh biomass burning aerosols produced from many fuels during FLAME-4 was analysed to determine the factors that control the variability in ω. Results show that ω varies strongly with fire-integrated modified combustion efficiency (MCEFI)—higher MCEFI results in lower ω values and greater spectral dependence of ω (Liu et al GRL 2014). A parameterization of ω as a function of MCEFI for fresh BB aerosols is derived from the laboratory data and is evaluated by field data, including BBOP. Our laboratory studies also demonstrate that BrC production correlates with BC indicating that that they are produced by a common mechanism that is driven by MCEFI (Saleh et al NGeo 2014). We show that BrC absorption is concentrated in the extremely low volatility component that favours long-range transport. We observe substantial absorption enhancement for internally mixed BC from diesel and wood combustion near London during ClearFlo. While the absorption enhancement is due to BC particles coated by co-emitted OC in urban regions, it increases with photochemical age in rural areas and is simulated by core-shell models. We measure BrC absorption that is concentrated in the extremely low volatility components and attribute it to wood burning. Our results support

  1. North American Monsoon Response to Eemian Climate Forcings and its Effect on Rocky Mountain Forests

    Science.gov (United States)

    Insel, N.; Berkelhammer, M. B.

    2017-12-01

    The key to recognizing and predicting future changes in regional climate and ecosystems lies in understanding the causes and characteristics of paleovariations. The Last Interglacial (LIG: 130-116 ka) is the most recent period in Earth history when temperatures are believed to have exceeded those of today. In this study, we are focusing on the response of the North American monsoon (NAM) to shifts in orbital forcings during LIG. In particular, we are using regional climate model (RegCM) simulations under LIG (115ka, 125 ka and 135 ka) and modern forcings to evaluate changes in the strength, timing, duration, and amount of moisture transported from different sources during the NAM season. Understanding these variations is critical to forecast seasonal supply of water to the southwestern U.S. under current warming conditions. In addition, cellulose extracted stable isotopes from Rocky Mountain Eemian wood samples provides both a tool to diagnose the model simulations and to evaluate the response of western U.S. tree species to changes in temperature and moisture availability. Our preliminary results indicate enhanced summer precipitation, wind shifts and changes in NAM characteristics in response to increased Northern Hemisphere insolation. The following features were observed: (1) The NAM strengthens and extends slightly more northward during the Eemian due to a shift in upper-level divergence. (2) The onset and duration of the NAM seems to be similar between modern and Eemian simulations. (3) Consistent with modern observations, simulations suggest a western NAM region in Arizona that receives most of its monsoonal moisture from the Gulf of California, while the eastern NAM region in New Mexico obtains most of its summer rains from the Gulf of Mexico. In the Eemian, we see a spatial shift from more depleted to more enriched source waters throughout the monsoon season. These changes in the summer climate are confirmed by the tree ring isotope data, which show a

  2. Global impact of road traffic on atmospheric chemical composition and on ozone climate forcing

    Science.gov (United States)

    Niemeier, Ulrike; Granier, Claire; Kornblueh, Luis; Walters, Stacy; Brasseur, Guy P.

    2006-05-01

    Automobile emissions are known to contribute to local air pollution and to photochemical smog in urban areas. The impact of road traffic on the chemical composition of the troposphere at the global scale and on climate forcing is less well quantified. Calculations performed with the chemical transport MOZART-2 model show that the concentrations of ozone and its precursors (NOx, CO, and hydrocarbons) are considerably enhanced in most regions of the Northern Hemisphere in response to current surface traffic. During summertime in the Northern Hemisphere, road traffic has increased the zonally averaged ozone concentration by more than 10% in the boundary layer and in the extratropics by approximately 6% at 500 hPa and 2.5% at 300 hPa. The summertime surface ozone concentrations have increased by typically 1-5 ppbv in the remote regions and by 5-20 ppbv in industrialized regions of the Northern Hemisphere. The corresponding ozone-related radiative forcing is 0.05 Wm-2. In order to assess the sensitivity of potential changes in road traffic intensity, two additional model cases were considered, in which traffic-related emissions in all regions of the world were assumed to be on a per capita basis the same as in Europe and in the United States, respectively. In the second and most dramatic case, the surface ozone concentration increases by 30-50 ppbv (50-100%) in south Asia as compared to the present situation. Under this assumption, the global radiative forcing due to traffic-generated ozone reaches 0.27 Wm-2.

  3. Climatic Forcing on Black Sigatoka Disease of Banana Crops in Urabá, Colombia

    Science.gov (United States)

    Ochoa, A.; Álvarez, P.; Poveda, G.; Buriticá, P.; Mira, J.

    2012-12-01

    Bananas are widely the most consumed fruit in the world and Colombia is one of the major producers and exporters of bananas worldwide. We analyzed the climatic forcing agents on banana crops in the Urabá region, the largest banana producer in Colombia. Although this crop is harvested continuously throughout the entire year, it exhibits climate driven seasonality. Black Sigatoka Disease (BSD) has been the most important threat for banana production worldwide. BSD attacks plant leaves producing small spots of dead material. When BSD is not treated, it can grow enough to damage the entire leaf, reducing both growth and developmental rates which may result in the loss of the plant. BSD is caused by Mycosphaerella fijiensis. This fungus is dispersed by wind with its inoculation occurring when there is water on the leaf. Thus, climatic variables such as wind, relative humidity of air (RH) and leaf wetness duration (LWD) all affect phenological phases of the banana crop (suckering, growing, flowering and harvesting). This study was carried out at the Cenibanano Experimental Plot located in Carepa (Urabá, Colombia) during 2007-2012. We used phytopathologic and weather data from the Cenibanano database along with climatic data from the North American Regional Reanalysis (NARR). BSD was diagnosed using the Biological Forecasting method. Results show that rainfall drives both plant and disease development rate. During wet periods the Foliar Emission Rate exceeds rates measured during dry periods. Although wetness is a positive factor for fungal reproduction (and BSD), it also heightens the chance for the plant to create more foliar tissue to fight against BSD. Hence, during wet periods the Severity Index of BSD is reduced in relation to dry periods. This effect was also observed at the inter-annual scale of the El Niño - South Oscillation (ENSO) phenomenon. During the ENSO warm/cold phase (El Niño/La Niña) rainfall anomalies in Colombia were observed as negative

  4. Biennial-Aligned Lunisolar-Forcing of ENSO: Implications for Simplified Climate Models

    Science.gov (United States)

    Pukite, P. R.

    2017-12-01

    implications for vastly simplifying global climate models due to the straightforward application of a well-known and well-calibrated forcing. [1] Na, Sung-Ho, et al. "Characteristics of Perturbations in Recent Length of Day and Polar Motion." Journal of Astronomy and Space Sciences 30 (2013): 33-41.

  5. The ocean's role in polar climate change: asymmetric Arctic and Antarctic responses to greenhouse gas and ozone forcing.

    Science.gov (United States)

    Marshall, John; Armour, Kyle C; Scott, Jeffery R; Kostov, Yavor; Hausmann, Ute; Ferreira, David; Shepherd, Theodore G; Bitz, Cecilia M

    2014-07-13

    In recent decades, the Arctic has been warming and sea ice disappearing. By contrast, the Southern Ocean around Antarctica has been (mainly) cooling and sea-ice extent growing. We argue here that interhemispheric asymmetries in the mean ocean circulation, with sinking in the northern North Atlantic and upwelling around Antarctica, strongly influence the sea-surface temperature (SST) response to anthropogenic greenhouse gas (GHG) forcing, accelerating warming in the Arctic while delaying it in the Antarctic. Furthermore, while the amplitude of GHG forcing has been similar at the poles, significant ozone depletion only occurs over Antarctica. We suggest that the initial response of SST around Antarctica to ozone depletion is one of cooling and only later adds to the GHG-induced warming trend as upwelling of sub-surface warm water associated with stronger surface westerlies impacts surface properties. We organize our discussion around 'climate response functions' (CRFs), i.e. the response of the climate to 'step' changes in anthropogenic forcing in which GHG and/or ozone-hole forcing is abruptly turned on and the transient response of the climate revealed and studied. Convolutions of known or postulated GHG and ozone-hole forcing functions with their respective CRFs then yield the transient forced SST response (implied by linear response theory), providing a context for discussion of the differing warming/cooling trends in the Arctic and Antarctic. We speculate that the period through which we are now passing may be one in which the delayed warming of SST associated with GHG forcing around Antarctica is largely cancelled by the cooling effects associated with the ozone hole. By mid-century, however, ozone-hole effects may instead be adding to GHG warming around Antarctica but with diminished amplitude as the ozone hole heals. The Arctic, meanwhile, responding to GHG forcing but in a manner amplified by ocean heat transport, may continue to warm at an accelerating rate.

  6. Climate responses to SATIRE and SIM-based spectral solar forcing in a 3D atmosphere-ocean coupled GCM

    Directory of Open Access Journals (Sweden)

    Wen Guoyong

    2017-01-01

    Full Text Available We apply two reconstructed spectral solar forcing scenarios, one SIM (Spectral Irradiance Monitor based, the other the SATIRE (Spectral And Total Irradiance REconstruction modeled, as inputs to the GISS (Goddard Institute for Space Studies GCMAM (Global Climate Middle Atmosphere Model to examine climate responses on decadal to centennial time scales, focusing on quantifying the difference of climate response between the two solar forcing scenarios. We run the GCMAM for about 400 years with present day trace gas and aerosol for the two solar forcing inputs. We find that the SIM-based solar forcing induces much larger long-term response and 11-year variation in global averaged stratospheric temperature and column ozone. We find significant decreasing trends of planetary albedo for both forcing scenarios in the 400-year model runs. However the mechanisms for the decrease are very different. For SATIRE solar forcing, the decreasing trend of planetary albedo is associated with changes in cloud cover. For SIM-based solar forcing, without significant change in cloud cover on centennial and longer time scales, the apparent decreasing trend of planetary albedo is mainly due to out-of-phase variation in shortwave radiative forcing proxy (downwelling flux for wavelength >330 nm and total solar irradiance (TSI. From the Maunder Minimum to present, global averaged annual mean surface air temperature has a response of ~0.1 °C to SATIRE solar forcing compared to ~0.04 °C to SIM-based solar forcing. For 11-year solar cycle, the global surface air temperature response has 3-year lagged response to either forcing scenario. The global surface air 11-year temperature response to SATIRE forcing is about 0.12 °C, similar to recent multi-model estimates, and comparable to the observational-based evidence. However, the global surface air temperature response to 11-year SIM-based solar forcing is insignificant and inconsistent with observation-based evidence.

  7. Emergent reorganization of an evolving experimental landscape under changing climatic forcing

    Science.gov (United States)

    Singh, A.; Tejedor, A.; Zaliapin, I. V.; Reinhardt, L.; Foufoula-Georgiou, E.

    2014-12-01

    Understanding landscape re-organization under changing climatic forcing is fundamental to advancing our understanding of geomorphic transport laws under transient conditions, developing predictive models of landscape response to external perturbations, and interpreting the stratigraphic record for past climates by incorporating possible regime shifts. Real landscape observations for long-term analysis are limited and to this end a high resolution controlled laboratory experiment was conducted at the St. Anthony Falls laboratory at the University of Minnesota. Elevation data were collected at temporal resolution of 5 mins and spatial resolution of 0.5 mm as the landscape approached steady state (for a constant uplift and precipitation rate) and in the transient state (under the same uplift and 5x precipitation). The results reveal rapid topographic re-organization under a five-fold precipitation increase with the fluvial regime expanding into previously debris dominated regime, accelerated erosion happening at hillslope scales, and rivers shifting from an erosion-limited to a transport-limited regime. By studying the space-time structure of the individual erosional and depositional events in terms of their size, location, clustering, and total volume we report complex space-time patterns of change which are scale-dependent and bounded by the river network topology. At the same time, the river network topology itself adjusts at smaller scales, with new channels added to accommodate increased hillslope erosional transport, further adjusting the landscape. Some new ideas related to landscape variability and entropy evolution at different scales during steady and transient states and the possibility of analyzing the self-organization with Optimal Mass Transport (OMT) metrics to infer possible underlying "optimality" principles governing the re-organization will also be presented.

  8. Tectonics, orbital forcing, global climate change, and human evolution in Africa: introduction to the African paleoclimate special volume.

    Science.gov (United States)

    Maslin, Mark A; Christensen, Beth

    2007-11-01

    The late Cenozoic climate of Africa is a critical component for understanding human evolution. African climate is controlled by major tectonic changes, global climate transitions, and local variations in orbital forcing. We introduce the special African Paleoclimate Issue of the Journal of Human Evolution by providing a background for and synthesis of the latest work relating to the environmental context for human evolution. Records presented in this special issue suggest that the regional tectonics, appearance of C(4) plants in East Africa, and late Cenozoic global cooling combined to produce a long-term drying trend in East Africa. Of particular importance is the uplift associated with the East African Rift Valley formation, which altered wind flow patterns from a more zonal to more meridinal direction. Results in this volume suggest a marked difference in the climate history of southern and eastern Africa, though both are clearly influenced by the major global climate thresholds crossed in the last 3 million years. Papers in this volume present lake, speleothem, and marine paleoclimate records showing that the East African long-term drying trend is punctuated by episodes of short, alternating periods of extreme wetness and aridity. These periods of extreme climate variability are characterized by the precession-forced appearance and disappearance of large, deep lakes in the East African Rift Valley and paralleled by low and high wind-driven dust loads reaching the adjacent ocean basins. Dating of these records show that over the last 3 million years such periods only occur at the times of major global climatic transitions, such as the intensification of Northern Hemisphere Glaciation (2.7-2.5 Ma), intensification of the Walker Circulation (1.9-1.7 Ma), and the Mid-Pleistocene Revolution (1-0.7 Ma). Authors in this volume suggest this onset occurs as high latitude forcing in both Hemispheres compresses the Intertropical Convergence Zone so that East Africa

  9. Evaluating the effects of terrestrial ecosystems, climate and carbon dioxide on weathering over geological time: a global-scale process-based approach

    Science.gov (United States)

    Taylor, Lyla L.; Banwart, Steve A.; Valdes, Paul J.; Leake, Jonathan R.; Beerling, David J.

    2012-01-01

    Global weathering of calcium and magnesium silicate rocks provides the long-term sink for atmospheric carbon dioxide (CO2) on a timescale of millions of years by causing precipitation of calcium carbonates on the seafloor. Catchment-scale field studies consistently indicate that vegetation increases silicate rock weathering, but incorporating the effects of trees and fungal symbionts into geochemical carbon cycle models has relied upon simple empirical scaling functions. Here, we describe the development and application of a process-based approach to deriving quantitative estimates of weathering by plant roots, associated symbiotic mycorrhizal fungi and climate. Our approach accounts for the influence of terrestrial primary productivity via nutrient uptake on soil chemistry and mineral weathering, driven by simulations using a dynamic global vegetation model coupled to an ocean–atmosphere general circulation model of the Earth's climate. The strategy is successfully validated against observations of weathering in watersheds around the world, indicating that it may have some utility when extrapolated into the past. When applied to a suite of six global simulations from 215 to 50 Ma, we find significantly larger effects over the past 220 Myr relative to the present day. Vegetation and mycorrhizal fungi enhanced climate-driven weathering by a factor of up to 2. Overall, we demonstrate a more realistic process-based treatment of plant fungal–geosphere interactions at the global scale, which constitutes a first step towards developing ‘next-generation’ geochemical models. PMID:22232768

  10. Sub-Saharan Northern African climate at the end of the twenty-first century: forcing factors and climate change processes

    Energy Technology Data Exchange (ETDEWEB)

    Patricola, C.M. [Cornell University, Department of Earth and Atmospheric Sciences, Ithaca, NY (United States); Texas A and M University, Department of Atmospheric Sciences, College Station, TX (United States); Cook, K.H. [The University of Texas at Austin, Department of Geological Sciences, Jackson School of Geosciences, Austin, TX (United States)

    2011-09-15

    A regional climate model, the Weather Research and Forecasting (WRF) Model, is forced with increased atmospheric CO{sub 2} and anomalous SSTs and lateral boundary conditions derived from nine coupled atmosphere-ocean general circulation models to produce an ensemble set of nine future climate simulations for northern Africa at the end of the twenty-first century. A well validated control simulation, agreement among ensemble members, and a physical understanding of the future climate change enhance confidence in the predictions. The regional model ensembles produce consistent precipitation projections over much of northern tropical Africa. A moisture budget analysis is used to identify the circulation changes that support future precipitation anomalies. The projected midsummer drought over the Guinean Coast region is related partly to weakened monsoon flow. Since the rainfall maximum demonstrates a southward bias in the control simulation in July-August, this may be indicative of future summer drying over the Sahel. Wetter conditions in late summer over the Sahel are associated with enhanced moisture transport by the West African westerly jet, a strengthening of the jet itself, and moisture transport from the Mediterranean. Severe drought in East Africa during August and September is accompanied by a weakened Indian monsoon and Somali jet. Simulations with projected and idealized SST forcing suggest that overall SST warming in part supports this regional model ensemble agreement, although changes in SST gradients are important over West Africa in spring and fall. Simulations which isolate the role of individual climate forcings suggest that the spatial distribution of the rainfall predictions is controlled by the anomalous SST and lateral boundary conditions, while CO{sub 2} forcing within the regional model domain plays an important secondary role and generally produces wetter conditions. (orig.)

  11. What's so local about global climate change? Testing social theories of environmental degradation to quantify the demographic, economic, and governmental factors associated with energy consumption and carbon dioxide emissions in U.S. metropolitan areas and counties

    Science.gov (United States)

    Tribbia, John Luke

    This research investigates the consequence of a crucial and not yet fully explored problem: the reluctance of the United States to sign and ratify international agreements, like Kyoto, that aim to mitigate climate change and its underlying social and ecological impacts. This unwillingness has inspired local governments, mayors, metropolitan area governance consortia, state governments, and governors to take on the climate challenge without the directive of the federal government. Local areas of the U.S. are experiencing climate-change-related impacts such as receding beach lines due to sea level rise and intense storms, fresh water shortages, and extreme weather events. As a result, researchers have begun to explore the human dimensions of climate change through an inquiry in: among many other topics, the vulnerability of local areas to the impacts of climate change and the forces shaping local areas' contribution to climate change. This study addresses the latter issue using the STIRPAT framework - a reformulated version of the I=(P)(A)(T) formulation that relates environmental impacts (I) to population growth (P), affluence (A), and technology (T). I address three questions that have thus far been poorly answered in prior research: "across the U.S., do local areas differ in the extent of their contribution to climate change?", "what are the causes of variation in energy use and carbon dioxide (CO2) emissions across local areas?" and "which social theories best explain the causes of variation in energy use and CO2 emissions across local areas?" To make strides in answering these questions and contribute to the understanding of local level drivers of energy consumption and emissions, this research analyzes the causes of variation in: energy use and CO2 emissions in the 100 largest U.S. metropolitan areas in chapter 4, the change in energy consumption between 2000 and 2005 for these metropolitan areas in chapter 5, and CO2 emissions in all U.S. counties in chapter 6

  12. A modeling study of effective radiative forcing and climate response due to increased methane concentration

    Directory of Open Access Journals (Sweden)

    Bing Xie

    2016-12-01

    Full Text Available An atmospheric general circulation model BCC_AGCM2.0 and observation data from ARIS were used to calculate the effective radiative forcing (ERF due to increased methane concentration since pre-industrial times and its impacts on climate. The ERF of methane from 1750 to 2011 was 0.46 W m−2 by taking it as a well-mixed greenhouse gas, and the inhomogeneity of methane increased its ERF by about 0.02 W m−2. The change of methane concentration since pre-industrial led to an increase of 0.31 °C in global mean surface air temperature and 0.02 mm d−1 in global mean precipitation. The warming was prominent over the middle and high latitudes of the Northern Hemisphere (with a maximum increase exceeding 1.4 °C. The precipitation notably increased (maximum increase of 1.8 mm d−1 over the ocean between 10°N and 20°N and significantly decreased (maximum decrease >–0.6 mm d−1 between 10°S and 10°N. These changes caused a northward movement of precipitation cell in the Intertropical Convergence Zone (ITCZ. Cloud cover significantly increased (by approximately 4% in the high latitudes in both hemispheres, and sharply decreased (by approximately 3% in tropical areas.

  13. Experimental evidence of dynamic re-organization of evolving landscapes under changing climatic forcing

    Science.gov (United States)

    Singh, Arvind; Tejedor, Alejandro; Zaliapin, Ilya; Reinhardt, Liam; Foufoula-Georgiou, Efi

    2015-04-01

    The aim of this study is to better understand the dynamic re-organization of an evolving landscape under a scenario of changing climatic forcing for improving our knowledge of geomorphic transport laws under transient conditions and developing predictive models of landscape response to external perturbations. Real landscape observations for long-term analysis are limited and to this end a high resolution controlled laboratory experiment was conducted at the St. Anthony Falls laboratory at the University of Minnesota. Elevation data were collected at temporal resolution of 5 mins and spatial resolution of 0.5 mm as the landscape approached steady state (constant uplift and precipitation rate) and in the transient state (under the same uplift and 5x precipitation). The results reveal rapid topographic re-organization under a five-fold precipitation increase with the fluvial regime expanding into the previously debris dominated regime, accelerated erosion happening at hillslope scales, and rivers shifting from an erosion-limited to a transport-limited regime. From a connectivity and clustering analysis of the erosional and depositional events, we demonstrate the strikingly different spatial patterns of landscape evolution under steady-state (SS) and transient-state (TS), even when the time under SS is "stretched" compared to that under TS such as to match the total volume and PDF of erosional and depositional amounts. We quantify the spatial coupling of hillslopes and channels and demonstrate that hillslopes lead and channels follow in re-organizing the whole landscape under such an amplified precipitation regime.

  14. Climate vs. carbon dioxide controls on biomass burning: a model analysis of the glacial-interglacial contrast

    Science.gov (United States)

    Calvo, M. Martin; Prentice, I. C.; Harrison, S. P.

    2014-02-01

    Climate controls fire regimes through its influence on the amount and types of fuel present and their dryness; CO2 availability, in turn, constrains primary production by limiting photosynthetic activity in plants. However, although fuel accumulation depends on biomass production, and hence CO2 availability, the links between atmospheric CO2 and biomass burning are not well known. Here a fire-enabled dynamic global vegetation model (the Land surface Processes and eXchanges model, LPX) is used to attribute glacial-interglacial changes in biomass burning to CO2 increase, which would be expected to increase primary production and therefore fuel loads even in the absence of climate change, vs. climate change effects. Four general circulation models provided Last Glacial Maximum (LGM) climate anomalies - that is, differences from the pre-industrial (PI) control climate - from the Palaeoclimate Modelling Intercomparison Project Phase 2, allowing the construction of four scenarios for LGM climate. Modelled carbon fluxes in biomass burning were corrected for the model's observed biases in contemporary biome-average values. With LGM climate and low CO2 (185 ppm) effects included, the modelled global flux was 70 to 80% lower at the LGM than in PI time. LGM climate with pre-industrial CO2 (280 ppm) however yielded unrealistic results, with global and Northern Hemisphere biomass burning fluxes greater than in the pre-industrial climate. Using the PI CO2 concentration increased the modelled LGM biomass burning fluxes for all climate models and latitudinal bands to between four and ten times their values under LGM CO2 concentration. It is inferred that a substantial part of the increase in biomass burning after the LGM must be attributed to the effect of increasing CO2 concentration on productivity and fuel load. Today, by analogy, both rising CO2 and global warming must be considered as risk factors for increasing biomass burning. Both effects need to be included in models to

  15. The polity and politics of carbon-dioxide taxation in small European states

    DEFF Research Database (Denmark)

    Andersen, Mikael Skou

    to the adoption of carbon dioxide taxation in only smaller countries in Europe. The research questions addressed by the present paper are how and why is it that small countries that in terms of emissions are virtually irrelevant to climate change and which are more open to forces of international competition...... are more susceptible to introduce carbon dioxide taxes ? It is hypothesized that features of the institutionalized patterns of policy-making, the polity of small states, can provide explanations for their climate politics, and ultimately the outcome policy in question....

  16. Feather retention force in broilers ante-, peri-, and post-mortem as influenced by electrical and carbon dioxide stunning.

    Science.gov (United States)

    Buhr, R J; Cason, J A; Rowland, G N

    1997-11-01

    Stunning and slaughter trials were conducted to evaluate the influence of stunning method (electrical 50 V alternating current, CO2 gas: 0 to 40% for 90 s or 40 to 60% for 30 s) on feather retention force (FRF) in commercial broilers. Feathers from the pectoral, sternal, and femoral feather tracts were sampled with a force gauge before stunning (ante-mortem) and contralaterally either after stunning (peri-mortem from 0.5 to 4 min) or after stunning and bleeding (post-mortem from 2 to 6 min). Prior to stunning, ante-mortem FRF values varied among assigned stunning methods only for the pectoral (7%) feather tract. After stunning, peri-mortem FRF values were higher only for the sternal tract (11% for 40 to 60% CO2 for 30 s); whereas after stunning and bleeding, post-mortem FRF values were lower than ante- or peri-mortem only for the sternal tract (10% lower for 40 to 60% CO2 for 30 s). Peri- and post-mortem FRF values did not differ among stunning methods for the pectoral and femoral feather tracts. Small changes in FRF values occurred from ante-mortem to peri-mortem (-1 to +12%), and from ante-mortem to post-mortem (-2 to +8%) across stunning methods. A significant increase was determined for only the pectoral tract (7%) from ante- to peri-mortem across stunning methods. Electrically stunned broilers that were not bled gained weight in excess of the 36 feathers removed (0.16%), apparently due to body surface water pickup during the brine-stunning process, whereas CO2-stunned broilers lost weight due to excretion of cloacal contents (-0.31 to -0.98%). The change in body weight among stunning methods was significant (P defeathering efficiency may not differ after scalding.

  17. Climate versus carbon dioxide controls on biomass burning: a model analysis of the glacial-interglacial contrast

    Science.gov (United States)

    Calvo, M. Martin; Prentice, I. C.; Harrison, S. P.

    2014-11-01

    Climate controls fire regimes through its influence on the amount and types of fuel present and their dryness. CO2 concentration constrains primary production by limiting photosynthetic activity in plants. However, although fuel accumulation depends on biomass production, and hence on CO2 concentration, the quantitative relationship between atmospheric CO2 concentration and biomass burning is not well understood. Here a fire-enabled dynamic global vegetation model (the Land surface Processes and eXchanges model, LPX) is used to attribute glacial-interglacial changes in biomass burning to an increase in CO2, which would be expected to increase primary production and therefore fuel loads even in the absence of climate change, vs. climate change effects. Four general circulation models provided last glacial maximum (LGM) climate anomalies - that is, differences from the pre-industrial (PI) control climate - from the Palaeoclimate Modelling Intercomparison Project Phase~2, allowing the construction of four scenarios for LGM climate. Modelled carbon fluxes from biomass burning were corrected for the model's observed prediction biases in contemporary regional average values for biomes. With LGM climate and low CO2 (185 ppm) effects included, the modelled global flux at the LGM was in the range of 1.0-1.4 Pg C year-1, about a third less than that modelled for PI time. LGM climate with pre-industrial CO2 (280 ppm) yielded unrealistic results, with global biomass burning fluxes similar to or even greater than in the pre-industrial climate. It is inferred that a substantial part of the increase in biomass burning after the LGM must be attributed to the effect of increasing CO2 concentration on primary production and fuel load. Today, by analogy, both rising CO2 and global warming must be considered as risk factors for increasing biomass burning. Both effects need to be included in models to project future fire risks.

  18. Economic Value of Narrowing the Uncertainty in Climate Sensitivity: Decadal Change in Shortwave Cloud Radiative Forcing and Low Cloud Feedback

    Science.gov (United States)

    Wielicki, B. A.; Cooke, R. M.; Golub, A. A.; Mlynczak, M. G.; Young, D. F.; Baize, R. R.

    2016-12-01

    Several previous studies have been published on the economic value of narrowing the uncertainty in climate sensitivity (Cooke et al. 2015, Cooke et al. 2016, Hope, 2015). All three of these studies estimated roughly 10 Trillion U.S. dollars for the Net Present Value and Real Option Value at a discount rate of 3%. This discount rate is the nominal discount rate used in the U.S. Social Cost of Carbon Memo (2010). The Cooke et al studies approached this problem by examining advances in accuracy of global temperature measurements, while the Hope 2015 study did not address the type of observations required. While temperature change is related to climate sensitivity, large uncertainties of a factor of 3 in current anthropogenic radiative forcing (IPCC, 2013) would need to be solved for advanced decadal temperature change observations to assist the challenge of narrowing climate sensitivity. The present study takes a new approach by extending the Cooke et al. 2015,2016 papers to replace observations of temperature change to observations of decadal change in the effects of changing clouds on the Earths radiative energy balance, a measurement known as Cloud Radiative Forcing, or Cloud Radiative Effect. Decadal change in this observation is direclty related to the largest uncertainty in climate sensitivity which is cloud feedback from changing amount of low clouds, primarily low clouds over the world's oceans. As a result, decadal changes in shortwave cloud radiative forcing are more directly related to cloud feedback uncertainty which is the dominant uncertainty in climate sensitivity. This paper will show results for the new approach, and allow an examination of the sensitivity of economic value results to different observations used as a constraint on uncertainty in climate sensitivity. The analysis suggests roughly a doubling of economic value to 20 Trillion Net Present Value or Real Option Value at 3% discount rate. The higher economic value results from two changes: a

  19. Global Climate Forcing from Albedo Change Caused by Large-scale Deforestation and Reforestation: Quantification and Attribution of Geographic Variation

    Science.gov (United States)

    Jiao, Tong; Williams, Christopher A.; Ghimire, Bardan; Masek, Jeffrey; Gao, Feng; Schaaf, Crystal

    2017-01-01

    Large-scale deforestation and reforestation have contributed substantially to historical and contemporary global climate change in part through albedo-induced radiative forcing, with meaningful implications for forest management aiming to mitigate climate change. Associated warming or cooling varies widely across the globe due to a range of factors including forest type, snow cover, and insolation, but resulting geographic variation remain spoorly described and has been largely based on model assessments. This study provides an observation-based approach to quantify local and global radiative forcings from large-scale deforestation and reforestation and further examines mechanisms that result in the spatial heterogeneity of radiative forcing. We incorporate a new spatially and temporally explicit land cover-specific albedo product derived from Moderate Resolution Imaging Spectroradiometer with a historical land use data set (Land Use Harmonization product). Spatial variation in radiative forcing was attributed to four mechanisms, including the change in snow-covered albedo, change in snow-free albedo, snow cover fraction, and incoming solar radiation. We find an albedo-only radiative forcing (RF) of -0.819 W m(exp -2) if year 2000 forests were completely deforested and converted to croplands. Albedo RF from global reforestation of present-day croplands to recover year 1700 forests is estimated to be 0.161 W m)exp -2). Snow-cover fraction is identified as the primary factor in determining the spatial variation of radiative forcing in winter, while the magnitude of the change in snow-free albedo is the primary factor determining variations in summertime RF. Findings reinforce the notion that, for conifers at the snowier high latitudes, albedo RF diminishes the warming from forest loss and the cooling from forest gain more so than for other forest types, latitudes, and climate settings.

  20. A Step towards Sustainable Society: The Awareness of Carbon Dioxide Emissions, Climate Change and Carbon Capture in Malaysia

    OpenAIRE

    Ghazali, Zulkipli; Zahid, Muhammad; Kee, Tan Siok; Ibrahim, M. Yussoff

    2016-01-01

    Public awareness is crucial to mitigate negative impacts on the environment. The aim of the study is to explore the level of public awareness in five states of Malaysia (Perak, Melaka, Johor, Pahang and Terengganu) regarding CO2 emissions, climate change and carbon capture and storage (CCS). A questionnaire floated for exploring public awareness regarding CO2 emissions, climate change and CCS. Based on the questionnaire data was collected from five states (Perak, Melaka, Johor, Pahang and Ter...

  1. Carbonaceous aerosols over China--review of observations, emissions, and climate forcing.

    Science.gov (United States)

    Wang, Linpeng; Zhou, Xuehua; Ma, Yujie; Cao, Zhaoyu; Wu, Ruidong; Wang, Wenxing

    2016-01-01

    Carbonaceous aerosols have been attracting attention due to the influence on visibility, air quality, and regional climate. Statistical analyses based on concentration levels, spatial-temporal variations, correlations, and organic carbon (OC) to element carbon (EC) ratios from published data of OC and EC in particulate matter (PM2.5 and PM10) were carried out in order to give a carbonaceous aerosol profile in China. The results showed maxima for OC of 29.5 ± 18.2 μg C m(-3) and for EC of 8.4 ± 6.3 μg C m(-3) in winter and minima for OC of 12.9 ± 7.7 μg C m(-3) in summer and for EC of 4.6 ± 2.8 μg C m(-3) in spring. In addition, OC and EC both had higher concentrations in urban than those in rural sites. Carbonaceous aerosol levels in China are about three to seven times higher compared to those in the USA and Europe. OC and EC occupied 20 ± 6 and 7 ± 3% of PM2.5 mass and 17 ± 7 and 5 ± 3% of PM10 mass, respectively, implying that carbonaceous aerosols are the main component of PM, especially OC. Secondary organic carbon (SOC) was a significant portion of PM and contributed 41 ± 26% to OC and 8 ± 6% to PM2.5 mass. The OC/EC ratio was 3.63 ± 1.73, which, along with the good correlation between OC and EC and the OC to EC slope of 2.29, signifies that coal combustion and/or vehicular exhaust is the dominated carbonaceous aerosol source in China. These provide a primary observation-based understanding of carbonaceous aerosol pollution in China and have a great significance in improving the emission inventory and climate forcing evaluation.

  2. Radiative forcing and climate metrics for ozone precursor emissions: the impact of multi-model averaging

    Directory of Open Access Journals (Sweden)

    C. R. MacIntosh

    2015-04-01

    Full Text Available Multi-model ensembles are frequently used to assess understanding of the response of ozone and methane lifetime to changes in emissions of ozone precursors such as NOx, VOCs (volatile organic compounds and CO. When these ozone changes are used to calculate radiative forcing (RF (and climate metrics such as the global warming potential (GWP and global temperature-change potential (GTP there is a methodological choice, determined partly by the available computing resources, as to whether the mean ozone (and methane concentration changes are input to the radiation code, or whether each model's ozone and methane changes are used as input, with the average RF computed from the individual model RFs. We use data from the Task Force on Hemispheric Transport of Air Pollution source–receptor global chemical transport model ensemble to assess the impact of this choice for emission changes in four regions (East Asia, Europe, North America and South Asia. We conclude that using the multi-model mean ozone and methane responses is accurate for calculating the mean RF, with differences up to 0.6% for CO, 0.7% for VOCs and 2% for NOx. Differences of up to 60% for NOx 7% for VOCs and 3% for CO are introduced into the 20 year GWP. The differences for the 20 year GTP are smaller than for the GWP for NOx, and similar for the other species. However, estimates of the standard deviation calculated from the ensemble-mean input fields (where the standard deviation at each point on the model grid is added to or subtracted from the mean field are almost always substantially larger in RF, GWP and GTP metrics than the true standard deviation, and can be larger than the model range for short-lived ozone RF, and for the 20 and 100 year GWP and 100 year GTP. The order of averaging has most impact on the metrics for NOx, as the net values for these quantities is the residual of the sum of terms of opposing signs. For example, the standard deviation for the 20 year GWP is 2–3

  3. The cohesive energy of uranium dioxide and thorium dioxide

    International Nuclear Information System (INIS)

    Childs, B.G.

    1958-08-01

    Theoretical values have been calculated of the heats of formation of uranium dioxide and thorium dioxide on the assumption that the atomic binding forces in these solids are predominantly ionic in character. The good agreement found between the theoretical and observed values shows that the ionic model may, with care, be used in calculating the energies of defects in the uranium and thorium dioxide crystal structures. (author)

  4. The role of forcing and internal dynamics in explaining the ''Medieval Climate Anomaly''

    Energy Technology Data Exchange (ETDEWEB)

    Goosse, Hugues; Crespin, Elisabeth; Dubinkina, Svetlana; Loutre, Marie-France; Sallaz-Damaz, Yoann [Universite Catholique de Louvain, Earth and Life Institute, Georges Lemaitre Centre for Earth and Climate Research, Louvain-la-Neuve (Belgium); Mann, Michael E. [Pennsylvania State University, Department of Meteorology and Earth and Environmental Systems Institute, University Park, PA (United States); Renssen, Hans [Vrije Universiteit Amsterdam, Section Climate Change and Landscape Dynamics, Department of Earth Sciences, Amsterdam (Netherlands); Shindell, Drew [NASA Goddard Institute for Space Studies, New York City, NY (United States)

    2012-12-15

    Proxy reconstructions suggest that peak global temperature during the past warm interval known as the Medieval Climate Anomaly (MCA, roughly 950-1250 AD) has been exceeded only during the most recent decades. To better understand the origin of this warm period, we use model simulations constrained by data assimilation establishing the spatial pattern of temperature changes that is most consistent with forcing estimates, model physics and the empirical information contained in paleoclimate proxy records. These numerical experiments demonstrate that the reconstructed spatial temperature pattern of the MCA can be explained by a simple thermodynamical response of the climate system to relatively weak changes in radiative forcing combined with a modification of the atmospheric circulation, displaying some similarities with the positive phase of the so-called Arctic Oscillation, and with northward shifts in the position of the Gulf Stream and Kuroshio currents. The mechanisms underlying the MCA are thus quite different from anthropogenic mechanisms responsible for modern global warming. (orig.)

  5. Climate-forced variability of suboxia and associated N-loses in the Pacific Ocean

    Science.gov (United States)

    Yang, S.; Gruber, N.; Long, M. C.; Vogt, M.

    2017-12-01

    The Eastern Tropical Pacific (ETP) hosts two of the world's three Oxygen Deficient Zones (ODZs), large bodies of suboxic water that are subject to high rates of water column denitrification. In the mean, these two ODZs are responsible for about 15 to 40% of all fixed N loss in the ocean, but little is known about how this loss varies in time. Here, we use a hindcast simulation with the ocean component of the NCAR Community Earth System Model over the period 1960 to 2009 to show that Pacific ODZ structures and their associated rates of N-loss are subject to strong climate forced variability and change. In particular, El Niño-Southern Oscillation (ENSO) drives large interannual variations in the rate of water column denitrification such that mature La Niña conditions exhibit peak denitrification rates that are up to 70% higher than the mean rates, and vice versa during El Niños. At the same time, we simulate large decadal trends in the rate of Pacific N-loss, which decreases by 10 Tg y-1 from the 1960s to the 1980s and subsequently increases by 30 Tg y-1 towards 2009. We demonstrate that this large variability is the result of wind-driven changes in circulation and isopycnal structure concurrently modifying the thermocline distribution of O2 and organic matter export. Finally, we show that the decadal trends in denitrification are recorded by the isotopic signature of particulate organic nitrogen in the ETP but that the interpretation of the signals is non trivial, reflecting both physical and biogeochemical changes as well as contamination by atmospheric pollutants.

  6. Future atmospheric abundances and climate forcings from scenarios of global and regional hydrofluorocarbon (HFC) emissions

    Science.gov (United States)

    Velders, Guus J. M.; Fahey, David W.; Daniel, John S.; Andersen, Stephen O.; McFarland, Mack

    2015-12-01

    Hydrofluorocarbons (HFCs) are manufactured for use as substitutes for ozone-depleting substances that are being phased out globally under Montreal Protocol regulations. While HFCs do not deplete ozone, many are potent greenhouse gases that contribute to climate change. Here, new global scenarios show that baseline emissions of HFCs could reach 4.0-5.3 GtCO2-eq yr-1 in 2050. The new baseline (or business-as-usual) scenarios are formulated for 10 HFC compounds, 11 geographic regions, and 13 use categories. The scenarios rely on detailed data reported by countries to the United Nations; projections of gross domestic product and population; and recent observations of HFC atmospheric abundances. In the baseline scenarios, by 2050 China (31%), India and the rest of Asia (23%), the Middle East and northern Africa (11%), and the USA (10%) are the principal source regions for global HFC emissions; and refrigeration (40-58%) and stationary air conditioning (21-40%) are the major use sectors. The corresponding radiative forcing could reach 0.22-0.25 W m-2 in 2050, which would be 12-24% of the increase from business-as-usual CO2 emissions from 2015 to 2050. National regulations to limit HFC use have already been adopted in the European Union, Japan and USA, and proposals have been submitted to amend the Montreal Protocol to substantially reduce growth in HFC use. Calculated baseline emissions are reduced by 90% in 2050 by implementing the North America Montreal Protocol amendment proposal. Global adoption of technologies required to meet national regulations would be sufficient to reduce 2050 baseline HFC consumption by more than 50% of that achieved with the North America proposal for most developed and developing countries.

  7. A simple framework for assessing the trade-off between the climate impact of aviation carbon dioxide emissions and contrails for a single flight

    International Nuclear Information System (INIS)

    A Irvine, E; J Hoskins, B; P Shine, K

    2014-01-01

    Persistent contrails are an important climate impact of aviation which could potentially be reduced by re-routing aircraft to avoid contrailing; however this generally increases both the flight length and its corresponding CO 2 emissions. Here, we provide a simple framework to assess the trade-off between the climate impact of CO 2 emissions and contrails for a single flight, in terms of the absolute global warming potential and absolute global temperature potential metrics for time horizons of 20, 50 and 100 years. We use the framework to illustrate the maximum extra distance (with no altitude changes) that can be added to a flight and still reduce its overall climate impact. Small aircraft can fly up to four times further to avoid contrailing than large aircraft. The results have a strong dependence on the applied metric and time horizon. Applying a conservative estimate of the uncertainty in the contrail radiative forcing and climate efficacy leads to a factor of 20 difference in the maximum extra distance that could be flown to avoid a contrail. The impact of re-routing on other climatically-important aviation emissions could also be considered in this framework. (letters)

  8. Carbon dioxide enhances fragility of ice crystals

    International Nuclear Information System (INIS)

    Qin Zhao; Buehler, Markus J

    2012-01-01

    Ice caps and glaciers cover 7% of the Earth, greater than the land area of Europe and North America combined, and play an important role in global climate. The small-scale failure mechanisms of ice fracture, however, remain largely elusive. In particular, little understanding exists about how the presence and concentration of carbon dioxide molecules, a significant component in the atmosphere, affects the propensity of ice to fracture. Here we use atomic simulations with the first-principles based ReaxFF force field capable of describing the details of chemical reactions at the tip of a crack, applied to investigate the effects of the presence of carbon dioxide molecules on ice fracture. Our result shows that increasing concentrations of carbon dioxide molecules significantly decrease the fracture toughness of the ice crystal, making it more fragile. Using enhanced molecular sampling with metadynamics we reconstruct the free energy landscape in varied chemical microenvironments and find that carbon dioxide molecules affect the bonds between water molecules at the crack tip and decrease their strength by altering the dissociation energy of hydrogen bonds. In the context of glacier dynamics our findings may provide a novel viewpoint that could aid in understanding the breakdown and melting of glaciers, suggesting that the chemical composition of the atmosphere can be critical to mediate the large-scale motion of large volumes of ice.

  9. Effects of climatic changes on carbon dioxide and water vapor fluxes in boreal forest ecosystems of European part of Russia

    International Nuclear Information System (INIS)

    Olchev, A; Kurbatova, J; Novenko, E; Desherevskaya, O; Krasnorutskaya, K

    2009-01-01

    Effects of possible climatic and vegetation changes on H 2 O and CO 2 fluxes in boreal forest ecosystems of the central part of European Russia were quantified using modeling and experimental data. The future pattern of climatic conditions for the period up to 2100 was derived using the global climatic model ECHAM5 (Roeckner et al 2003 The Atmospheric General Circulation Model ECHAM 5. PART I: Model Description, Report 349 (Hamburg: Max-Planck Institute for Meteorology) p 127) with the A1B emission scenario. The possible trends of future vegetation changes were obtained by reconstructions of vegetation cover and paleoclimatic conditions in the Late Pleistocene and Holocene, as provided from pollen and plant macrofossil analysis of profiles in the Central Forest State Natural Biosphere Reserve (CFSNBR). Applying the method of paleoanalogues demonstrates that increasing the mean annual temperature, even by 1-2 deg. C, could result in reducing the proportion of spruce in boreal forest stands by up to 40%. Modeling experiments, carried out using a process-based Mixfor-SVAT model, show that the expected future climatic and vegetation changes lead to a significant increase of net ecosystem exchange (NEE) and gross primary productivity (GPP) of the boreal forests. Despite the expected warming and moistening of the climate, the modeling experiments indicate a relatively weak increase of annual evapotranspiration (ET) and even a reduction of transpiration (TR) rates of forest ecosystems compared to present conditions.

  10. Elucidating dynamic responses of North Pacific fish populations to climatic forcing: Influence of life-history strategy

    Science.gov (United States)

    Yatsu, A.; Aydin, K. Y.; King, J. R.; McFarlane, G. A.; Chiba, S.; Tadokoro, K.; Kaeriyama, M.; Watanabe, Y.

    2008-05-01

    In order to explore mechanistic linkages between low-frequency ocean/climate variability, and fish population responses, we undertook comparative studies of time-series of recruitment-related productivity and the biomass levels of fish stocks representing five life-history strategies in the northern North Pacific between the 1950s and the present. We selected seven species: Japanese sardine ( Sardinopus melanostictus) and California sardine ( Sardinopus sagax) (opportunistic strategists), walleye pollock ( Theragra chalcogramma, intermediate strategist), pink salmon ( Oncorhynchus gorbuscha, salmonic strategist), sablefish ( Anoplopoma fimbria) and Pacific halibut ( Hippoglossus stenolepis) (periodic strategists) and spiny dogfish ( Squalus acanthias, equilibrium strategist). The responses in terms of productivity of sardine, pink salmon, sablefish and halibut to climatic regime shifts were generally immediate, delayed, or no substantial responses depending on the particular regime shift year and fish stock (population). In walleye pollock, there were some periods of high productivity and low productivity, but not coincidental to climatic regime shifts, likely due to indirect climate forcing impacts on both bottom-up and top-down processes. Biomass of zooplankton and all fish stocks examined, except for spiny dogfish whose data were limited, indicated a decadal pattern with the most gradual changes in periodic strategists and most intensive and rapid changes in opportunistic strategists. Responses of sardine productivity to regime shifts were the most intense, probably due to the absence of density-dependent effects and the availability of refuges from predators when sardine biomass was extremely low. Spiny dogfish were least affected by environmental variability. Conversely, spiny dogfish are likely to withstand only modest harvest rates due to their very low intrinsic rate of increase. Thus, each life-history strategy type had a unique response to climatic

  11. Reproducing multi-model ensemble average with Ensemble-averaged Reconstructed Forcings (ERF) in regional climate modeling

    Science.gov (United States)

    Erfanian, A.; Fomenko, L.; Wang, G.

    2016-12-01

    Multi-model ensemble (MME) average is considered the most reliable for simulating both present-day and future climates. It has been a primary reference for making conclusions in major coordinated studies i.e. IPCC Assessment Reports and CORDEX. The biases of individual models cancel out each other in MME average, enabling the ensemble mean to outperform individual members in simulating the mean climate. This enhancement however comes with tremendous computational cost, which is especially inhibiting for regional climate modeling as model uncertainties can originate from both RCMs and the driving GCMs. Here we propose the Ensemble-based Reconstructed Forcings (ERF) approach to regional climate modeling that achieves a similar level of bias reduction at a fraction of cost compared with the conventional MME approach. The new method constructs a single set of initial and boundary conditions (IBCs) by averaging the IBCs of multiple GCMs, and drives the RCM with this ensemble average of IBCs to conduct a single run. Using a regional climate model (RegCM4.3.4-CLM4.5), we tested the method over West Africa for multiple combination of (up to six) GCMs. Our results indicate that the performance of the ERF method is comparable to that of the MME average in simulating the mean climate. The bias reduction seen in ERF simulations is achieved by using more realistic IBCs in solving the system of equations underlying the RCM physics and dynamics. This endows the new method with a theoretical advantage in addition to reducing computational cost. The ERF output is an unaltered solution of the RCM as opposed to a climate state that might not be physically plausible due to the averaging of multiple solutions with the conventional MME approach. The ERF approach should be considered for use in major international efforts such as CORDEX. Key words: Multi-model ensemble, ensemble analysis, ERF, regional climate modeling

  12. A Study of Direct and Cloud-Mediated Radiative Forcing of Climate Due to Aerosols

    Science.gov (United States)

    Yu, Shao-Cai

    1999-01-01

    The Intergovernmental Panel on Climate Change (IPCC) has reported that in the southeastern US and eastern China, the general greenhouse warming due to anthropogenic gaseous emissions is dominated by the cooling effect of anthropogenic aerosols. To verify this model prediction in eastern China and southeastern US, we analyzed regional patterns of climate changes at 72 stations in eastern China during 1951- 94 (44 years), and at 52 stations in the southeastern US during 1949-94 (46 years) to detect the fingerprint of aerosol radiative forcing. It was found that the mean rates of change of annual mean daily, maximum, minimum temperatures and diurnal temperature range (DTR) in eastern China were 0.8, -0.2, 1.8, and -2.0 C/100 years respectively, while the mean rates of change of annual mean daily, maximum, minimum temperatures and DTR in the southeastern US were -0.2, -0.6, 0.2, and -0.8 C/100 years, respectively. This indicates that the high rate of increase in annual mean minimum temperature in eastern China results in a slightly warming trend of daily temperature, while the high rate of decrease in annual mean maximum temperature and low rate of increase in annual mean minimum temperature lead to the cooling trend of daily temperature in the southeastern US. We found that the warming from the longwave forcing due to both greenhouse gases and aerosols was completely counteracted by the shortwave aerosol forcing in the southeastern US in the past 46 years. A slightly overall warming trend in eastern China is evident; winters have become milder. This finding is explained by hypothesizing that increasing energy usage during the past 44 years has resulted in more coal and biomass burning, thus increasing the emission of absorbing soot and organic aerosols in eastern China. Such emissions, in addition to well-known Asia dust and greenhouse gases, may be responsible for the winter warming trend in eastern China that we have reported here. The sensitivity of aerosol

  13. Future Climate Impacts of Direct Radiative Forcing Anthropogenic Aerosols, Tropospheric Ozone, and Long-lived Greenhouse Gases

    Science.gov (United States)

    Chen, Wei-Ting; Liao, Hong; Seinfeld, John H.

    2007-01-01

    Long-lived greenhouse gases (GHGs) are the most important driver of climate change over the next century. Aerosols and tropospheric ozone (O3) are expected to induce significant perturbations to the GHG-forced climate. To distinguish the equilibrium climate responses to changes in direct radiative forcing of anthropogenic aerosols, tropospheric ozone, and GHG between present day and year 2100, four 80-year equilibrium climates are simulated using a unified tropospheric chemistry-aerosol model within the Goddard Institute for Space Studies (GISS) general circulation model (GCM) 110. Concentrations of sulfate, nitrate, primary organic (POA) carbon, secondary organic (SOA) carbon, black carbon (BC) aerosols, and tropospheric ozone for present day and year 2100 are obtained a priori by coupled chemistry-aerosol GCM simulations, with emissions of aerosols, ozone, and precursors based on the Intergovernmental Panel on Climate Change (IPCC) Special Report on Emissions Scenario (SRES) A2. Changing anthropogenic aerosols, tropospheric ozone, and GHG from present day to year 2100 is predicted to perturb the global annual mean radiative forcing by +0.18 (considering aerosol direct effects only), +0.65, and +6.54 W m(sup -2) at the tropopause, and to induce an equilibrium global annual mean surface temperature change of +0.14, +0.32, and +5.31 K, respectively, with the largest temperature response occurring at northern high latitudes. Anthropogenic aerosols, through their direct effect, are predicted to alter the Hadley circulation owing to an increasing interhemispheric temperature gradient, leading to changes in tropical precipitation. When changes in both aerosols and tropospheric ozone are considered, the predicted patterns of change in global circulation and the hydrological cycle are similar to those induced by aerosols alone. GHG-induced climate changes, such as amplified warming over high latitudes, weakened Hadley circulation, and increasing precipitation over the

  14. a Study of the Impact of Doubling Carbon Dioxide and Solar Radiation Variations on the Climate System.

    Science.gov (United States)

    Chu, Shaoping

    The exchange of moisture and heat between the atmosphere and the Earth's surface fundamentally affect the dynamics and thermodynamics of the climate system. In order to trace moisture flow through the climate system and examine its impact on climate, a hydrologic cycle and a land energy balance have been developed and incorporated into a coupled climate-thermodynamic sea ice (CCSI) model. The expanded CCSI model has been tested by comparing computed climate parameters with available observations and GCM modeling results. In general, the expanded model does a good job in simulating the large scale features of the atmospheric circulation and precipitation in both space and time. The expanded model has been used to examine the possibility that increased levels of CO_2 in the atmosphere may induce the growth of Northern Hemisphere ice sheets. Results of the study indicate that if summer ice albedo is high enough, and there is some mechanism for initially maintaining ice through the summer season, then it may be possible to have ice sheet growth under the conditions CO_2 induced warming, mainly the result of decreased summer ice melt in response to the higher land ice albedo, and not an increase in precipitation. The expanded model has also been used to examine the impact of Milankovitch solar radiation variations on the climate system, to study the mechanisms that produce glacial-interglacial cycles, especially with respect to the initiation of ice sheets. The results show the Milankovitch solar radiation variations affect the climate system most in the polar regions with the mean annual surface air temperature varying directly in response to changes in the annually averaged incoming solar radiation. However, the seasonal variations in the surface air temperatures are much more complex with large magnitude variations for brief times during the year. The study indicates that ice sheets may start to grow under the conditions of low insolation that occurred at 25, 70, and

  15. The impacts of future climate and carbon dioxide changes on the average and variability of US maize yields under two emission scenarios

    International Nuclear Information System (INIS)

    Urban, Daniel W; Lobell, David B; Sheffield, Justin

    2015-01-01

    The United States is the largest producer of maize in the world, a crop for which demand continues to rise rapidly. Past studies have projected that climate change will negatively impact mean maize yields in this region, while at the same time increasing yield variability. However, some have questioned the accuracy of these projections because they are often based on indirect measures of soil moisture, have failed to explicitly capture the potential interactions between temperature and soil moisture availability, and often omit the beneficial effects of elevated carbon dioxide (CO 2 ) on transpiration efficiency. Here we use a new detailed dataset on field-level yields in Iowa, Indiana, and Illinois, along with fine-resolution daily weather data and moisture reconstructions, to evaluate the combined effects of moisture and heat on maize yields in the region. Projected climate change scenarios over this region from a suite of CMIP5 models are then used to assess future impacts and the differences between two contrasting emissions scenarios (RCP 4.5 and RCP 8.5). We show that (i) statistical models which explicitly account for interactions between heat and moisture, which have not been represented in previous empirical models, lead to significant model improvement and significantly higher projected yield variability under warming and drying trends than when accounting for each factor independently; (ii) inclusion of the benefits of elevated CO 2 significantly reduces impacts, particularly for yield variability; and (iii) net damages from climate change and CO 2 become larger for the higher emission scenario in the latter half of the 21st century, and significantly so by the end of century. (paper)

  16. Simulating future wheat yield under climate change, carbon dioxide enrichment and technology improvement in Iran. Case study: Azarbaijan region

    Energy Technology Data Exchange (ETDEWEB)

    Mansouri, H.; Raei, Y.; Zaeim, A.N.

    2015-07-01

    Climate change and technology development can affect crop productivity in future conditions. Precise estimation of crops yield change as affected by climate and technology in the future is an effective approach for management strategies. The aim of this study was to estimate the impacts of climate change, technology improvement, CO2 enrichment, and overall impacts on wheat yield under future conditions. Wheat yield was projected for three future time periods (2020, 2050 and 2080) compared to baseline year (2011) under two scenarios of IPCC Special Report on Emission Scenarios (SRES) including SRES-A2 as regional economic scenario and SRES-B1 as global environmental scenario in Azarbaijan region (NW of Iran). A linear regression model, describing the relationship between wheat yield and historical year, was developed to investigate technology development effect. The decision support system for agro-technology transfer (DSSAT4.5) was used to evaluate the influence of climate change on wheat yield. The most positive effects were found for wheat yield as affected by technology in all studied regions. Under future climate change, the SRES projected a decrease in yield, especially in West Azarbaijan region. When the effects of elevated CO2 were considered, all regions resulted to increase in wheat yield. Considering all components effect in comparison with baseline (2011), yield increase would range from 5% to 38% across all times, scenarios and regions. According to our findings, it seems that we may expect a higher yield of wheat in NW Iran in the future if technology development continues as well as past years. (Author)

  17. Unexpected weak seasonal climate in the western Mediterranean region during MIS 31, a high-insolation forced interglacial

    Science.gov (United States)

    Oliveira, Dulce; Sánchez Goñi, Maria Fernanda; Naughton, Filipa; Polanco-Martínez, J. M.; Jimenez-Espejo, Francisco J.; Grimalt, Joan O.; Martrat, Belen; Voelker, Antje H. L.; Trigo, Ricardo; Hodell, David; Abrantes, Fátima; Desprat, Stéphanie

    2017-04-01

    Marine Isotope Stage 31 (MIS 31) is an important analogue for ongoing and projected global warming, yet key questions remain about the regional signature of its extreme orbital forcing and intra-interglacial variability. Based on a new direct land-sea comparison in SW Iberian margin IODP Site U1385 we examine the climatic variability between 1100 and 1050 ka including the ;super interglacial; MIS 31, a period dominated by the 41-ky obliquity periodicity. Pollen and biomarker analyses at centennial-scale-resolution provide new insights into the regional vegetation, precipitation regime and atmospheric and oceanic temperature variability on orbital and suborbital timescales. Our study reveals that atmospheric and SST warmth during MIS 31 was not exceptional in this region highly sensitive to precession. Unexpectedly, this warm stage stands out as a prolonged interval of a temperate and humid climate regime with reduced seasonality, despite the high insolation (precession minima values) forcing. We find that the dominant forcing on the long-term temperate forest development was obliquity, which may have induced a decrease in summer dryness and associated reduction in seasonal precipitation contrast. Moreover, this study provides the first evidence for persistent atmospheric millennial-scale variability during this interval with multiple forest decline events reflecting repeated cooling and drying episodes in SW Iberia. Our direct land-sea comparison shows that the expression of the suborbital cooling events on SW Iberian ecosystems is modulated by the predominance of high or low-latitude forcing depending on the glacial/interglacial baseline climate states. Severe dryness and air-sea cooling is detected under the larger ice volume during glacial MIS 32 and MIS 30. The extreme episodes, which in their climatic imprint are similar to the Heinrich events, are likely related to northern latitude ice-sheet instability and a disruption of the Atlantic Meridional Overturning

  18. Assessing the role of North Atlantic freshwater forcing in millennial scale climate variability: a tropical Atlantic perspective

    Energy Technology Data Exchange (ETDEWEB)

    Dahl, Kristina A [Massachusetts Institute of Technology/Woods Hole Oceanographic Institution Joint Program, Woods Hole, MA (United States); Broccoli, Anthony J [Rutgers University, Department of Environmental Sciences, New Brunswick, NJ (United States); Stouffer, Ronald J [Geophysical Fluid Dynamics Laboratory, Princeton, NJ (United States)

    2005-03-01

    This study analyzes a three-member ensemble of experiments, in which 0.1 Sv of freshwater was applied to the North Atlantic for 100 years in order to address the potential for large freshwater inputs in the North Atlantic to drive abrupt climate change. The model used is the GFDL R30 coupled ocean-atmosphere general circulation model. We focus in particular on the effects of this forcing on the tropical Atlantic region, which has been studied extensively by paleoclimatologists. In response to the freshwater forcing, North Atlantic meridional overturning circulation is reduced to roughly 40% by the end of the 100 year freshwater pulse. Consequently, the North Atlantic region cools by up to 8 C. The extreme cooling of the North Atlantic increases the pole-to-equator temperature gradient and requires more heat be provided to the high latitude Atlantic from the tropical Atlantic. To accommodate the increased heat requirement, the ITCZ shifts southward to allow for greater heat transport across the equator. Accompanying this southward ITCZ shift, the Northeast trade winds strengthen and precipitation patterns throughout the tropical Atlantic are altered. Specifically, precipitation in Northeast Brazil increases, and precipitation in Africa decreases slightly. In addition, we find that surface air temperatures warm over the tropical Atlantic and over Africa, but cool over northern South America. Sea-surface temperatures in the tropical Atlantic warm slightly with larger warm anomalies developing in the thermocline. These responses are robust for each member of the ensemble, and have now been identified by a number of freshwater forcing studies using coupled OAGCMs. The model responses to freshwater forcing are generally smaller in magnitude, but have the same direction, as paleoclimate data from the Younger Dryas suggest. In certain cases, however, the model responses and the paleoclimate data directly contradict one another. Discrepancies between the model simulations

  19. Forced Climate Changes in West Antarctica and the Indo-Pacific by Northern Hemisphere Ice Sheet Topography

    Science.gov (United States)

    Jones, T. R.; Roberts, W. H. G.; Steig, E. J.; Cuffey, K. M.; Markle, B. R.; White, J. W. C.

    2017-12-01

    The behavior of the Indo-Pacific climate system across the last deglaciation is widely debated. Resolving these debates requires long term and continuous climate proxy records. Here, we use an ultra-high resolution and continuous water isotope record from an ice core in the Pacific sector of West Antarctica. In conjunction with the HadCM3 coupled ocean-atmosphere GCM, we demonstrate that the climate of both West Antarctica and the Indo-Pacific were substantially altered during the last deglaciation by the same forcing mechanism. Critically, these changes are not dependent on ENSO strength, but rather the location of deep tropical convection, which shifts at 16 ka in response to climate perturbations induced by the Laurentide Ice Sheet. The changed rainfall patterns in the tropics explain the deglacial shift from expanded-grasslands to rainforest-dominated ecosystems in Indonesia. High-frequency climate variability in the Southern Hemisphere is also changed, through a tropical Pacific teleconnection link dependent on the propogration of Rossby Waves.

  20. Holocene climate change and the evidence for solar and other forcings

    NARCIS (Netherlands)

    Beer, J.; van Geel, B.; Battarbee, R.W.; Binney, H.A.

    2008-01-01

    Future climate change may have considerable effects on the hydrologic cycle and temperature, with significant consequences for sea level, food production, world economy, health, and biodiversity. How and why does the natural climate system vary on decadal to millennial time-scales? Do we

  1. BECCS as a climate measure. A report on carbon dioxide storage from biomass in a Swedish-Norwegian perspective; BECCS som klimataatgaerd. En rapport om koldioxidlagring fraan biomassa i ett svensk-norskt perspektiv

    Energy Technology Data Exchange (ETDEWEB)

    Karlsson, Henrik; Bystroem, Lennart; Wiklund, Josef

    2010-09-15

    As the economic costs for combating the threat of climate change are considerable, accurate priorities have to be set and economic efficiency must be sought. On this basis, this report aims at examining the Swedish and Norwegian opportunities and potential for geologic storage of carbon dioxide from biomass, or BECCS (Bio Energy with Carbon Capture and Storage). So-called biogenic carbon dioxide is part of the renewable carbon cycle. Carbon dioxide is extracted from the atmosphere into trees and crops as they grow, and is released when they are combusted or decompose. Therefore, biogenic carbon dioxide does not contribute to the increase of greenhouse gases in the atmosphere. On the contrary, these emissions may become part of the solution to the climate problem. When carbon dioxide that has been captured from the atmosphere by biomass is stored geologically, a flow of carbon from the atmosphere into the underground is created. With a scientific term, this is called negative emissions, or permanent carbon dioxide sinks. Since we already today have a level of 390 ppm of carbon dioxide in the atmosphere, and this level is rising by 2 ppm per year, negative emissions are vital if we are to achieve climate targets such as 350 or 400 ppm. Due to the large amount of biomass that is processed in the pulp industry as well as the use of biomass for energy production, there are several and large point sources of biogenic carbon dioxide emissions in Sweden. The 61 largest Swedish plants are together emitting more than 31 million tons of biogenic carbon dioxide per year. In Norway, these industries are significantly smaller with the major point emissions of biogenic carbon amounting to less than 2 million tons per year. Because of this the continued analysis focuses on Swedish emissions. However, there are very good opportunities for carbon dioxide storage in the Norwegian part of the North Sea. This is not the case in Sweden. Suitable conditions for carbon dioxide storage are

  2. Analytically tractable climate-carbon cycle feedbacks under 21st century anthropogenic forcing

    Science.gov (United States)

    Lade, Steven J.; Donges, Jonathan F.; Fetzer, Ingo; Anderies, John M.; Beer, Christian; Cornell, Sarah E.; Gasser, Thomas; Norberg, Jon; Richardson, Katherine; Rockström, Johan; Steffen, Will

    2018-05-01

    Changes to climate-carbon cycle feedbacks may significantly affect the Earth system's response to greenhouse gas emissions. These feedbacks are usually analysed from numerical output of complex and arguably opaque Earth system models. Here, we construct a stylised global climate-carbon cycle model, test its output against comprehensive Earth system models, and investigate the strengths of its climate-carbon cycle feedbacks analytically. The analytical expressions we obtain aid understanding of carbon cycle feedbacks and the operation of the carbon cycle. Specific results include that different feedback formalisms measure fundamentally the same climate-carbon cycle processes; temperature dependence of the solubility pump, biological pump, and CO2 solubility all contribute approximately equally to the ocean climate-carbon feedback; and concentration-carbon feedbacks may be more sensitive to future climate change than climate-carbon feedbacks. Simple models such as that developed here also provide workbenches for simple but mechanistically based explorations of Earth system processes, such as interactions and feedbacks between the planetary boundaries, that are currently too uncertain to be included in comprehensive Earth system models.

  3. Nonlinearities, scale-dependence, and individualism of boreal forest trees to climate forcing

    Science.gov (United States)

    Wolken, J. M.; Mann, D. H.; Grant, T. A., III; Lloyd, A. H.; Hollingsworth, T. N.

    2013-12-01

    Our understanding of the climate-growth relationships of trees are complicated by the nonlinearity and variability of these responses through space and time. Furthermore, trees growing at the same site may exhibit opposing growth responses to climate, a phenomenon termed growth divergence. To date the majority of dendrochronological studies in Interior Alaska have involved white spruce growing at treeline, even though black spruce is the most abundant tree species. Although changing climate-growth relationships have been observed in black spruce, there is little known about the multivariate responses of individual trees to temperature and precipitation and whether or not black spruce exhibits growth divergences similar to those documented for white spruce. To evaluate the occurrence of growth divergences in black spruce, we collected cores from trees growing on a steep, north-facing toposequence having a gradient in environmental parameters. Our overall goal was to assess how the climate-growth relationships of black spruce change over space and time. Specifically, we evaluated how topography influences the climate-growth relationships of black spruce and if the growth responses to climate are homogeneous. At the site-level most trees responded negatively to temperature and positively to precipitation, while at the tree-level black spruce exhibited heterogenous growth responses to climate that varied in both space (i.e., between sites) and time (i.e., seasonally and annually). There was a dominant response-type at each site, but there was also considerable variability in the proportion of trees exhibiting each response-type combination. Even in a climatically extreme setting like Alaska's boreal forest, tree responses to climate variability are spatially and temporally complex, as well as highly nonlinear.

  4. Chemical and climatic drivers of radiative forcing due to changes in stratospheric and tropospheric ozone over the 21st century

    Science.gov (United States)

    Banerjee, Antara; Maycock, Amanda C.; Pyle, John A.

    2018-02-01

    The ozone radiative forcings (RFs) resulting from projected changes in climate, ozone-depleting substances (ODSs), non-methane ozone precursor emissions and methane between the years 2000 and 2100 are calculated using simulations from the UM-UKCA chemistry-climate model (UK Met Office's Unified Model containing the United Kingdom Chemistry and Aerosols sub-model). Projected measures to improve air-quality through reductions in non-methane tropospheric ozone precursor emissions present a co-benefit for climate, with a net global mean ozone RF of -0.09 W m-2. This is opposed by a positive ozone RF of 0.05 W m-2 due to future decreases in ODSs, which is driven by an increase in tropospheric ozone through stratosphere-to-troposphere transport of air containing higher ozone amounts. An increase in methane abundance by more than a factor of 2 (as projected by the RCP8.5 scenario) is found to drive an ozone RF of 0.18 W m-2, which would greatly outweigh the climate benefits of non-methane tropospheric ozone precursor reductions. A small fraction (˜ 15 %) of the ozone RF due to the projected increase in methane results from increases in stratospheric ozone. The sign of the ozone RF due to future changes in climate (including the radiative effects of greenhouse gases, sea surface temperatures and sea ice changes) is shown to be dependent on the greenhouse gas emissions pathway, with a positive RF (0.05 W m-2) for RCP4.5 and a negative RF (-0.07 W m-2) for the RCP8.5 scenario. This dependence arises mainly from differences in the contribution to RF from stratospheric ozone changes. Considering the increases in tropopause height under climate change causes only small differences (≤ |0.02| W m-2) for the stratospheric, tropospheric and whole-atmosphere RFs.

  5. Atmosphere, water, sun, carbon dioxide, weather, climate, living - some fundamental terms; Atmosphaere, Wasser, Sonne, Kohlenstoffdioxid, Wetter, Klima, Leben - einige Grundbegriffe

    Energy Technology Data Exchange (ETDEWEB)

    Hopp, Vollrath

    2012-07-01

    The author of the book under consideration explains the physical, chemical and meteorological principles. The knowledge of these fundamentals is necessary in order to understand the weather in its manifold manifestations. Solar energy, atmosphere, oceans and continents are interrelated. Large amounts of energy are exchanged at their interfaces causing high temperature differences and strong materials flows. A historical review shows that the climatic change is determined by changes in solar activity, cosmic radiation, inclination of the earth's axis (from about 24.5 to 22.5 ) in periods of up to 41,000 years, the Earth's magnetic field, the gravitation and by large volcanic eruptions.

  6. Synchronous fire activity in the tropical high Andes: an indication of regional climate forcing

    NARCIS (Netherlands)

    Roman-Cuesta, R.M.; Carmona-Moreno, C.; Lizcano, G.; New, M.; Silman, M.R.; Knoke, T.; Malhi, Y.; Oliveras Menor, I.; Asbjornsen, H.; Vuille, M.

    2014-01-01

    Global climate models suggest enhanced warming of the tropical mid and upper troposphere, with larger temperature rise rates at higher elevations. Changes in fire activity are amongst the most significant ecological consequences of rising temperatures and changing hydrological properties in

  7. Carbon Disulfide (CS2) Mechanisms in Formation of Atmospheric Carbon Dioxide (CO2) Formation from Unconventional Shale Gas Extraction and Processing Operations and Global Climate Change.

    Science.gov (United States)

    Rich, Alisa L; Patel, Jay T

    2015-01-01

    Carbon disulfide (CS2) has been historically associated with the production of rayon, cellophane, and carbon tetrachloride. This study identifies multiple mechanisms by which CS2 contributes to the formation of CO2 in the atmosphere. CS2 and other associated sulfide compounds were found by this study to be present in emissions from unconventional shale gas extraction and processing (E&P) operations. The breakdown products of CS2; carbonyl sulfide (COS), carbon monoxide (CO), and sulfur dioxide (SO2) are indirect greenhouse gases (GHGs) that contribute to CO2 levels in the atmosphere. The heat-trapping nature of CO2 has been found to increase the surface temperature, resulting in regional and global climate change. The purpose of this study is to identify five mechanisms by which CS2 and the breakdown products of CS2 contribute to atmospheric concentrations of CO2. The five mechanisms of CO2 formation are as follows: Chemical Interaction of CS2 and hydrogen sulfide (H2S) present in natural gas at high temperatures, resulting in CO2 formation;Combustion of CS2 in the presence of oxygen producing SO2 and CO2;Photolysis of CS2 leading to the formation of COS, CO, and SO2, which are indirect contributors to CO2 formation;One-step hydrolysis of CS2, producing reactive intermediates and ultimately forming H2S and CO2;Two-step hydrolysis of CS2 forming the reactive COS intermediate that reacts with an additional water molecule, ultimately forming H2S and CO2. CS2 and COS additionally are implicated in the formation of SO2 in the stratosphere and/or troposphere. SO2 is an indirect contributor to CO2 formation and is implicated in global climate change.

  8. Comparison of hybrid spectral-decomposition artificial neural network models for understanding climatic forcing of groundwater levels

    Science.gov (United States)

    Abrokwah, K.; O'Reilly, A. M.

    2017-12-01

    Groundwater is an important resource that is extracted every day because of its invaluable use for domestic, industrial and agricultural purposes. The need for sustaining groundwater resources is clearly indicated by declining water levels and has led to modeling and forecasting accurate groundwater levels. In this study, spectral decomposition of climatic forcing time series was used to develop hybrid wavelet analysis (WA) and moving window average (MWA) artificial neural network (ANN) models. These techniques are explored by modeling historical groundwater levels in order to provide understanding of potential causes of the observed groundwater-level fluctuations. Selection of the appropriate decomposition level for WA and window size for MWA helps in understanding the important time scales of climatic forcing, such as rainfall, that influence water levels. Discrete wavelet transform (DWT) is used to decompose the input time-series data into various levels of approximate and details wavelet coefficients, whilst MWA acts as a low-pass signal-filtering technique for removing high-frequency signals from the input data. The variables used to develop and validate the models were daily average rainfall measurements from five National Atmospheric and Oceanic Administration (NOAA) weather stations and daily water-level measurements from two wells recorded from 1978 to 2008 in central Florida, USA. Using different decomposition levels and different window sizes, several WA-ANN and MWA-ANN models for simulating the water levels were created and their relative performances compared against each other. The WA-ANN models performed better than the corresponding MWA-ANN models; also higher decomposition levels of the input signal by the DWT gave the best results. The results obtained show the applicability and feasibility of hybrid WA-ANN and MWA-ANN models for simulating daily water levels using only climatic forcing time series as model inputs.

  9. Climate change convention : reallocation of carbon dioxide emissions; Convenzione sui cambiamenti climatici: ipotesi per una assegnazione di quote di emissioni di anidride carbonica

    Energy Technology Data Exchange (ETDEWEB)

    Turchetti, P; Venanzi, M [ENEA, Centro Ricerche Casaccia, Rome (Italy). Dip. Ambiente

    1995-07-01

    In 1992, during the United Nation`s Conference on Environment and Development, held in Rio de Janeiro, the Framework Convention on Climate Change was signed. The ultimate objective of this Convention is the control and the reduction of greenhouse gas releases from human activities, to achieve stabilization of greenhouse gas concentrations in the atmosphere. The purpose of this research is to provide a reallocation of carbon dioxide important greenhouse gas, among nine countries representing the different geopolitical worldwide situations. Demographic, socioeconomic and environmental criteria have been taken into account. Some of these issues have been proposed in the international negotiating context. In order to apportion emissions the Analytic Hierarchy Process (AHP) has been used. The AHP is a multi objective decision-making technique employing a method of pairwise comparisons to rank order alternatives of a problem formulated in a hierarchic structure by computing the largest eigenvalue of the pairwise comparisons matrix. Moreover, the AHP approach enables one to deal with both quantitative and qualitative factors in a logical fashion. The findings summarize the different indicators considered representing the proposals of the parties involved in the international debate.

  10. Influence of various forcings on global climate in historical times using a coupled atmosphere-ocean general circulation model

    DEFF Research Database (Denmark)

    Stendel, Martin; Mogensen, Irene A.; Christensen, Jens H.

    2006-01-01

    The results of a simulation of the climate of the last five centuries with a state-of-the-art coupled atmosphere-ocean general circulation model are presented. The model has been driven with most relevant forcings, both natural (solar variability, volcanic aerosol) and anthropogenic (greenhouse...... gases, sulphate aerosol, land-use changes). In contrast to previous GCM studies, we have taken into account the latitudinal dependence of volcanic aerosol and the changing land cover for a period covering several centuries. We find a clear signature of large volcanic eruptions in the simulated...

  11. Recent advances in understanding secondary organic aerosol: Implications for global climate forcing: Advances in Secondary Organic Aerosol

    Energy Technology Data Exchange (ETDEWEB)

    Shrivastava, Manish [Pacific Northwest National Laboratory, Richland Washington USA; Cappa, Christopher D. [Department of Civil and Environmental Engineering, University of California, Davis California USA; Fan, Jiwen [Pacific Northwest National Laboratory, Richland Washington USA; Goldstein, Allen H. [Department of Environmental Science, Policy and Management and Department of Civil and Environmental Engineering, University of California, Berkeley California USA; Guenther, Alex B. [Department of Earth System Science, University of California, Irvine California USA; Jimenez, Jose L. [Cooperative Institute for Research in Environmental Sciences and Department of Chemistry and Biochemistry, University of Colorado Boulder, Boulder Colorado USA; Kuang, Chongai [Brookhaven National Laboratory, Upton New York USA; Laskin, Alexander [Pacific Northwest National Laboratory, Richland Washington USA; Martin, Scot T. [School of Engineering and Applied Sciences and Department of Earth and Planetary Sciences, Harvard University, Cambridge Massachusetts USA; Ng, Nga Lee [School of Chemical and Biomolecular Engineering and School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta Georgia USA; Petaja, Tuukka [Department of Physics, University of Helsinki, Helsinki Finland; Pierce, Jeffrey R. [Department of Atmospheric Science, Colorado State University, Fort Collins Colorado USA; Rasch, Philip J. [Pacific Northwest National Laboratory, Richland Washington USA; Roldin, Pontus [Department of Physics, Lund University, Lund Sweden; Seinfeld, John H. [Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena California USA; Shilling, John [Pacific Northwest National Laboratory, Richland Washington USA; Smith, James N. [Department of Earth System Science, University of California, Irvine California USA; Thornton, Joel A. [Department of Atmospheric Sciences, University of Washington, Seattle Washington USA; Volkamer, Rainer [Cooperative Institute for Research in Environmental Sciences and Department of Chemistry and Biochemistry, University of Colorado Boulder, Boulder Colorado USA; Wang, Jian [Brookhaven National Laboratory, Upton New York USA; Worsnop, Douglas R. [Aerodyne Research, Inc., Billerica Massachusetts USA; Zaveri, Rahul A. [Pacific Northwest National Laboratory, Richland Washington USA; Zelenyuk, Alla [Pacific Northwest National Laboratory, Richland Washington USA; Zhang, Qi [Department of Environmental Toxicology, University of California, Davis California USA

    2017-06-01

    Anthropogenic emissions and land-use changes have modified atmospheric aerosol concentrations and size distributions over time. Understanding pre-industrial conditions and changes in organic aerosol due to anthropogenic activities is important because these features 1) influence estimates of aerosol radiative forcing and 2) can confound estimates of the historical response of climate to increases in greenhouse gases (e.g. the ‘climate sensitivity’). Secondary organic aerosol (SOA), formed in the atmosphere by oxidation of organic gases, represents a major fraction of global submicron-sized atmospheric organic aerosol. Over the past decade, significant advances in understanding SOA properties and formation mechanisms have occurred through a combination of laboratory and field measurements, yet current climate models typically do not comprehensively include all important SOA-relevant processes. Therefore, major gaps exist at present between current measurement-based knowledge on the one hand and model implementation of organic aerosols on the other. The critical review herein summarizes some of the important developments in understanding SOA formation that could potentially have large impacts on our understanding of aerosol radiative forcing and climate. We highlight the importance of some recently discovered processes and properties that influence the growth of SOA particles to sizes relevant for clouds and radiative forcing, including: formation of extremely low-volatility organics in the gas-phase; isoprene epoxydiols (IEPOX) multi-phase chemistry; particle-phase oligomerization; and physical properties such as viscosity. In addition, this review also highlights some of the important processes that involve interactions between natural biogenic emissions and anthropogenic emissions, such as the role of sulfate and oxides of nitrogen (NOx) on SOA formation from biogenic volatile organic compounds. Studies that relate the observed evolution of organic aerosol

  12. Toward explaining the Holocene carbon dioxide and carbon isotope records: Results from transient ocean carbon cycle-climate simulations

    Science.gov (United States)

    Menviel, L.; Joos, F.

    2012-03-01

    The Bern3D model was applied to quantify the mechanisms of carbon cycle changes during the Holocene (last 11,000 years). We rely on scenarios from the literature to prescribe the evolution of shallow water carbonate deposition and of land carbon inventory changes over the glacial termination (18,000 to 11,000 years ago) and the Holocene and modify these scenarios within uncertainties. Model results are consistent with Holocene records of atmospheric CO2 and δ13C as well as the spatiotemporal evolution of δ13C and carbonate ion concentration in the deep sea. Deposition of shallow water carbonate, carbonate compensation of land uptake during the glacial termination, land carbon uptake and release during the Holocene, and the response of the ocean-sediment system to marine changes during the termination contribute roughly equally to the reconstructed late Holocene pCO2 rise of 20 ppmv. The 5 ppmv early Holocene pCO2 decrease reflects terrestrial uptake largely compensated by carbonate deposition and ocean sediment responses. Additional small contributions arise from Holocene changes in sea surface temperature, ocean circulation, and export productivity. The Holocene pCO2 variations result from the subtle balance of forcings and processes acting on different timescales and partly in opposite direction as well as from memory effects associated with changes occurring during the termination. Different interglacial periods with different forcing histories are thus expected to yield different pCO2 evolutions as documented by ice cores.

  13. Response of a tundra ecosytem to elevated atmospheric carbon dioxide and CO2-induced climate change. Final report

    International Nuclear Information System (INIS)

    Oechel, W.C.

    1996-11-01

    The overall objective of this research was to document current patterns of CO 2 flux in selected locations of the circumpolar arctic, and to develop the information necessary to predict how these fluxes may be affected by climate change. In fulfillment of these objectives, net CO 2 flux was measured at several sites on the North Slope of Alaska during the 1990-94 growing season (June-August) to determine the local and regional patterns, of seasonal CO 2 exchange. In addition, net CO 2 flux was measured in the Russian and Icelandic Arctic to determine if the patterns of CO 2 exchange observed in Arctic Alaska were representative of the circumpolar arctic, while cold-season CO 2 flux measurements were carried out during the 1993-94 winter season to determine the magnitude of CO 2 efflux not accounted for by the growing season measurements. Manipulations of soil water table depth and surface temperature, which were identified from the extensive measurements as being the most important variables in determining the magnitude and direction of net CO 2 exchange, were carried out during the 1993-94 growing seasons in tussock and wet sedge tundra ecosystems. Finally, measurements of CH 4 flux were also measured at several of the North Slope study sites during the 1990-91 growing seasons. Measurements were made on small (e.g. 0.5 m 2 ) plots using a portable gas-exchange system and cuvette. The sample design allowed frequent measurements of net CO 2 exchange and respiration over diurnal and seasonal cycles, and a large spatial extent that incorporated both locally and regionally diverse tundra surface types. Measurements both within and between ecosystem types typically extended over soil water table depth and temperature gradients, allowing for the indirect analysis of the effects of anticipated climate change scenarios on net CO 2 exchange. In situ experiments provided a direct means for testing hypotheses

  14. Cholera and shigellosis in Bangladesh: similarities and differences in population dynamics under climate forcing

    Science.gov (United States)

    Pascual, M.; Cash, B.; Reiner, R.; King, A.; Emch, M.; Yunus, M.; Faruque, A. S.

    2012-12-01

    The influence of climate variability on the population dynamics of infectious diseases is considered a large scale, regional, phenomenon, and as such, has been previously addressed for cholera with temporal models that do not incorporate fine-scale spatial structure. In our previous work, evidence for a role of ENSO (El Niño Southern Oscillation) on cholera in Bangladesh was elucidated, and shown to influence the regional climate through precipitation. With a probabilistic spatial model for cholera dynamics in the megacity of Dhaka, we found that the action of climate variability (ENSO and flooding) is localized: there is a climate-sensitive urban core that acts to propagate risk to the rest of the city. Here, we consider long-term surveillance data for shigellosis, another diarrheal disease that coexists with cholera in Bangladesh. We compare the patterns of association with climate variables for these two diseases in a rural setting, as well as the spatial structure in their spatio-temporal dynamics in an urban one. Evidence for similar patterns is presented, and discussed in the context of the differences in the routes of transmission of the two diseases and the proposed role of an environmental reservoir in cholera. The similarities provide evidence for a more general influence of hydrology and of socio-economic factors underlying human susceptibility and sanitary conditions.

  15. Interannual to multidecadal climate forcings on groundwater resources of the U.S. West Coast

    Science.gov (United States)

    Velasco, Elzie M.; Gurdak, Jason J.; Dickinson, Jesse; Ferré, T.P.A.; Corona, Claudia

    2017-01-01

    Study regionThe U.S. West Coast, including the Pacific Northwest and California Coastal Basins aquifer systems.Study focusGroundwater response to interannual to multidecadal climate variability has important implications for security within the water–energy–food nexus. Here we use Singular Spectrum Analysis to quantify the teleconnections between AMO, PDO, ENSO, and PNA and precipitation and groundwater level fluctuations. The computer program DAMP was used to provide insight on the influence of soil texture, depth to water, and mean and period of a surface infiltration flux on the damping of climate signals in the vadose zone.New hydrological insights for the regionWe find that PDO, ENSO, and PNA have significant influence on precipitation and groundwater fluctuations across a north-south gradient of the West Coast, but the lower frequency climate modes (PDO) have a greater influence on hydrologic patterns than higher frequency climate modes (ENSO and PNA). Low frequency signals tend to be preserved better in groundwater fluctuations than high frequency signals, which is a function of the degree of damping of surface variable fluxes related to soil texture, depth to water, mean and period of the infiltration flux. The teleconnection patterns that exist in surface hydrologic processes are not necessarily the same as those preserved in subsurface processes, which are affected by damping of some climate variability signals within infiltrating water.

  16. Study of Radiative Forcing of Dust Aerosols and its impact on Climate Characteristics

    KAUST Repository

    Qureshi, Fawwad H

    2012-01-01

    The purpose of following project is to study the effect of dust aerosols on the radiative forcing which is directly related to the surface temperature. A single column radiative convective model is used for simulation purpose. A series

  17. Influence of the side functionalization of quinquethiophene-S,S-dioxides on the morphology of blends with poly(3-hexylthiophene): scanning force microscopy reveals.

    Science.gov (United States)

    Ridolfi, Giovanni; Favaretto, Laura; Barbarella, Giovanna; Camaioni, Nadia; Samorì, Paolo

    2006-06-01

    Blends of an electron donor, i.e. a regioregular poly(3-hexylthiophene) (P3HT), with electron acceptors, a series of soluble quinquethiophene-S,S-dioxides (T5Os) bearing different alkyl side groups were self-assembled at surfaces. Scanning Force Microscopy (SFM) studies revealed that while the T5O symmetrically functionalized with two hexyl groups in the central thiophene (1) self-organizes into micrometer sized crystals embedded in a grainy matrix of P3HT, by substituting the central thiophene of 1 with one hexyl and one methyl unit (2) smaller and less anisotropic crystals of the acceptor having a sub-micrometer scale size were formed. The generation of these crystals is due to the joint effect of different non-covalent intermolecular interactions between the T5Os that self-segregate from the P3HT. By derivatizing the compound 1 with cyclo-hexyl moieties in the four external thiophenes molecule 3 was obtained. Such system was found to assemble into grainy disordered structures when co-deposited with P3HT, providing evidence for the absence of a phase segregation between the two components. Generally, the self-assembly at surfaces is governed by the interplay of intramolecular as well as intermolecular and interfacial interactions. In the present case, the cyclo-hexyl side groups in 3 both induce an intramolecular loss of planarity of the thiophene rings and hinders intermolecular interactions, reducing the tendency of the molecules to self-associate forming large crystals, whereas the symmetrical functionalization of the two central thiophenes with hexyl chains favours the crystallization of the T5O. The reported results demonstrate that subtle differences in the chemical functionalization can lead to different types of molecular architectures at surfaces. This is of importance since controlling the self-organization of pi-conjugated molecules at surfaces towards pre-programmed assemblies is a viable approach to enhance their electronic and luminescent properties

  18. Climatic effects of 1950–2050 changes in US anthropogenic aerosols – Part 1: Aerosol trends and radiative forcing

    Directory of Open Access Journals (Sweden)

    D. G. Streets

    2012-04-01

    Full Text Available We calculate decadal aerosol direct and indirect (warm cloud radiative forcings from US anthropogenic sources over the 1950–2050 period. Past and future aerosol distributions are constructed using GEOS-Chem and historical emission inventories and future projections from the IPCC A1B scenario. Aerosol simulations are evaluated with observed spatial distributions and 1980–2010 trends of aerosol concentrations and wet deposition in the contiguous US. Direct and indirect radiative forcing is calculated using the GISS general circulation model and monthly mean aerosol distributions from GEOS-Chem. The radiative forcing from US anthropogenic aerosols is strongly localized over the eastern US. We find that its magnitude peaked in 1970–1990, with values over the eastern US (east of 100° W of −2.0 W m−2 for direct forcing including contributions from sulfate (−2.0 W m−2, nitrate (−0.2 W m−2, organic carbon (−0.2 W m−2, and black carbon (+0.4 W m−2. The uncertainties in radiative forcing due to aerosol radiative properties are estimated to be about 50%. The aerosol indirect effect is estimated to be of comparable magnitude to the direct forcing. We find that the magnitude of the forcing declined sharply from 1990 to 2010 (by 0.8 W m−2 direct and 1.0 W m−2 indirect, mainly reflecting decreases in SO2 emissions, and project that it will continue declining post-2010 but at a much slower rate since US SO2 emissions have already declined by almost 60% from their peak. This suggests that much of the warming effect of reducing US anthropogenic aerosol sources has already been realized. The small positive radiative forcing from US BC emissions (+0.3 W m−2 over the eastern US in 2010; 5% of the global forcing from anthropogenic BC emissions worldwide suggests that a US emission control strategy focused on BC would have only limited climate benefit.

  19. Climatic Effects of 1950-2050 Changes in US Anthropogenic Aerosols. Part 1; Aerosol Trends and Radiative Forcing

    Science.gov (United States)

    Leibensperger, E. M.; Mickley, L. J.; Jacob, D. J.; Chen, W.-T.; Seinfeld, J. H.; Nenes, A.; Adams, P. J.; Streets, D. G.; Kumar, N.; Rind, D.

    2012-01-01

    We calculate decadal aerosol direct and indirect (warm cloud) radiative forcings from US anthropogenic sources over the 1950-2050 period. Past and future aerosol distributions are constructed using GEOS-Chem and historical emission inventories and future projections from the IPCC A1B scenario. Aerosol simulations are evaluated with observed spatial distributions and 1980-2010 trends of aerosol concentrations and wet deposition in the contiguous US. Direct and indirect radiative forcing is calculated using the GISS general circulation model and monthly mean aerosol distributions from GEOS-Chem. The radiative forcing from US anthropogenic aerosols is strongly localized over the eastern US. We find that its magnitude peaked in 1970-1990, with values over the eastern US (east of 100 deg W) of -2.0Wm(exp-2 for direct forcing including contributions from sulfate (-2.0Wm-2), nitrate (-0.2Wm(exp-2), organic carbon (-0.2Wm(exp-2), and black carbon (+0.4Wm(exp-2). The uncertainties in radiative forcing due to aerosol radiative properties are estimated to be about 50 %. The aerosol indirect effect is estimated to be of comparable magnitude to the direct forcing. We find that the magnitude of the forcing declined sharply from 1990 to 2010 (by 0.8Wm(exp-2) direct and 1.0Wm(exp-2 indirect), mainly reflecting decreases in SO2 emissions, and project that it will continue declining post-2010 but at a much slower rate since US SO2 emissions have already declined by almost 60% from their peak. This suggests that much of the warming effect of reducing US anthropogenic aerosol sources has already been realized. The small positive radiative forcing from US BC emissions (+0.3Wm(exp-2 over the eastern US in 2010; 5% of the global forcing from anthropogenic BC emissions worldwide) suggests that a US emission control strategy focused on BC would have only limited climate benefit.

  20. Investigating the Linear Dependence of Direct and Indirect Radiative Forcing on Emission of Carbonaceous Aerosols in a Global Climate Model

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yanju [Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana IL USA; Wang, Hailong [Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland WA USA; Singh, Balwinder [Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland WA USA; Ma, Po-Lun [Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland WA USA; Rasch, Philip J. [Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland WA USA; Bond, Tami C. [Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana IL USA

    2018-02-02

    The linearity of dependence of aerosol direct and indirect radiative forcing (DRF and IRF) on emissions is essential to answer the policy-relevant question on how the change in forcing would result from a change in emission. In this study, the forcing-to-emission relationship is investigated for black carbon (BC) and primary organic carbon (OC) emitted from North America and Asia. Direct and indirect radiative forcing of BC and OC are simulated with the Community Atmosphere Model (CAM5.1). Two diagnostics are introduced to aid in policy-relevant discussion: emission-normalized forcing (ENF) and linearity (R). DRF is linearly related to emission for both BC and OC from the two regions and emission-normalized DRF is similar, within 15%. IRF is linear to emissions for weaker sources and regions far from source (North American BC and OC), while for large emission sources and near source regions (Asian OC) the response of forcing to emission is sub-linear. In North America emission-normalized IRF (ENIRF) is 2-4 times higher than that in Asia. The difference among regions and species is primarily caused by failure of accumulation mode particles to become CCN, and then to activate into CDNC. Optimal aggregation area (30ºx 30º) has been used to communicate the regional variation of forcing-to-emission relationship. For IRF, only 15-40% of the Earth’s surface is significantly affected by the two emission regions, but the forcing in these regions comprises most of the global impact. Linearity of IRF occurs in about two-thirds of the significant regions except for Asian OC. ENF is an effective tool to estimate forcing changes due to reduction of surface emissions, as long as there is sufficient attention to the causes of nonlinearity in the simulations used to derive ENIRF (emission into polluted regions and emission elevation). The differences in ENIRF have important implications for policy decisions. Lower ENIRF in more polluted region like Asia means that reductions of

  1. Elevated atmospheric CO2 negatively impacts photosynthesis through radiative forcing and physiology-mediated climate feedback

    Science.gov (United States)

    Zhu, Peng; Zhuang, Qianlai; Ciais, Philippe; Welp, Lisa; Li, Wenyu; Xin, Qinchuan

    2017-02-01

    Increasing atmospheric CO2 affects photosynthesis involving directly increasing leaf carboxylation rates, stomatal closure, and climatic effects. The direct effects are generally thought to be positive leading to increased photosynthesis, while its climatic effects can be regionally positive or negative. These effects are usually considered to be independent from each other, but they are in fact coupled through interactions between land surface exchanges of gases and heat and the physical climate system. In particular, stomatal closure reduces evapotranspiration and increases sensible heat emissions from ecosystems, leading to decreased atmospheric moisture and precipitation and local warming. We use a coupled earth system model to attribute the influence of the increase in CO2 on gross primary productivity (GPP) during the period of 1930-2011. In our model, CO2 radiative effects cause climate change that has only a negligible effect on global GPP (a reduction of 0.9 ± 2% during the last 80 years) because of opposite responses between tropical and northern biomes. On the other hand, CO2 physiological effects on GPP are both positive, by increased carboxylation rates and water use efficiency (7.1 ± 0.48% increase), and negative, by vegetation-climate feedback reducing precipitation, as a consequence of decreased transpiration and increased sensible heat in areas without water limitation (2.7 ± 1.76% reduction).When considering the coupled atmosphere-vegetation system, negative climate feedback on photosynthesis and plant growth due to the current level of CO2 opposes 29-38% of the gains from direct fertilization effects.

  2. Response of a tundra ecosytem to elevated atmospheric carbon dioxide and CO{sub 2}-induced climate change. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Oechel, W.C.

    1996-11-01

    The overall objective of this research was to document current patterns of CO{sub 2} flux in selected locations of the circumpolar arctic, and to develop the information necessary to predict how these fluxes may be affected by climate change. In fulfillment of these objectives, net CO{sub 2} flux was measured at several sites on the North Slope of Alaska during the 1990-94 growing season (June-August) to determine the local and regional patterns, of seasonal CO{sub 2} exchange. In addition, net CO{sub 2} flux was measured in the Russian and Icelandic Arctic to determine if the patterns of CO{sub 2} exchange observed in Arctic Alaska were representative of the circumpolar arctic, while cold-season CO{sub 2} flux measurements were carried out during the 1993-94 winter season to determine the magnitude of CO{sub 2} efflux not accounted for by the growing season measurements. Manipulations of soil water table depth and surface temperature, which were identified from the extensive measurements as being the most important variables in determining the magnitude and direction of net CO{sub 2} exchange, were carried out during the 1993-94 growing seasons in tussock and wet sedge tundra ecosystems. Finally, measurements of CH{sub 4} flux were also measured at several of the North Slope study sites during the 1990-91 growing seasons. Measurements were made on small (e.g. 0.5 m{sup 2}) plots using a portable gas-exchange system and cuvette. The sample design allowed frequent measurements of net CO{sub 2} exchange and respiration over diurnal and seasonal cycles, and a large spatial extent that incorporated both locally and regionally diverse tundra surface types. Measurements both within and between ecosystem types typically extended over soil water table depth and temperature gradients, allowing for the indirect analysis of the effects of anticipated climate change scenarios on net CO{sub 2} exchange. In situ experiments provided a direct means for testing hypotheses.

  3. Response of a tundra ecosystem to elevated atmospheric carbon dioxide and CO{sub 2}-induced climate change. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Oechel, W.C.

    1996-11-01

    The overall objective of this research was to document current patterns of CO{sub 2} flux in selected locations of the circumpolar arctic, and to develop the information necessary to predict how these fluxes may be affected by climate change. In fulfillment of these objectives, net CO{sub 2} flux was measured at several sites on the North Slope of Alaska during the 1990--94 growing season (June--August) to determine the local and regional patterns of seasonal CO{sub 2} exchange. In addition, net CO{sub 2} flux was measured in the Russian and Icelandic Arctic to determine if the patterns of CO{sub 2} exchange observed in Arctic Alaska were representative of the circumpolar Arctic, while cold-season CO{sub 2} flux measurements were carried out during the 1993--94 winter season to determine the magnitude of CO{sub 2} efflux not accounted for by the growing season measurements. Manipulations of soil water table depth and surface temperature, which were identified from the extensive measurements as being the most important variables in determining the magnitude and direction of net CO{sub 2} exchange, were carried out during the 1993--94 growing seasons in tussock and wet sedge tundra ecosystems. Finally, measurements of CH{sub 4} flux were also measured at several of the North Slope study sites during the 1990--91 growing seasons.

  4. Forcing of a photochemical air quality model with atmospheric fields simulated by a regional climate model

    CSIR Research Space (South Africa)

    Naidoo, M

    2010-10-01

    Full Text Available to the enhanced greenhouse effect (e.g. Engelbrecht et al, 2009). Such changes are likely to influence the future transport and chemistry of air pollutants over the region. The complexity in which climate change may affect regional air quality is evident...

  5. Climatic forcing before, during, and after the 8.2 Kyr B.P. global ...

    Indian Academy of Sciences (India)

    This paper attempts at full characterization of the unique global 8.2 Kyr B.P. cooling event. Signifi- ... of its global character and magnitude and occur- rence in the ... in the 1 A.U. interplanetary space, and is inversely correlated with solar activity. It is not influenced by any changes in the geomagnetic field strength or climate.

  6. The CSIRO Mk3L climate system model version 1.0 – Part 2: Response to external forcings

    Directory of Open Access Journals (Sweden)

    S. J. Phipps

    2012-05-01

    Full Text Available The CSIRO Mk3L climate system model is a coupled general circulation model, designed primarily for millennial-scale climate simulation and palaeoclimate research. Mk3L includes components which describe the atmosphere, ocean, sea ice and land surface, and combines computational efficiency with a stable and realistic control climatology. It is freely available to the research community. This paper evaluates the response of the model to external forcings which correspond to past and future changes in the climate system.

    A simulation of the mid-Holocene climate is performed, in which changes in the seasonal and meridional distribution of incoming solar radiation are imposed. Mk3L correctly simulates increased summer temperatures at northern mid-latitudes and cooling in the tropics. However, it is unable to capture some of the regional-scale features of the mid-Holocene climate, with the precipitation over Northern Africa being deficient. The model simulates a reduction of between 7 and 15% in the amplitude of El Niño-Southern Oscillation, a smaller decrease than that implied by the palaeoclimate record. However, the realism of the simulated ENSO is limited by the model's relatively coarse spatial resolution.

    Transient simulations of the late Holocene climate are then performed. The evolving distribution of insolation is imposed, and an acceleration technique is applied and assessed. The model successfully captures the temperature changes in each hemisphere and the upward trend in ENSO variability. However, the lack of a dynamic vegetation scheme does not allow it to simulate an abrupt desertification of the Sahara.

    To assess the response of Mk3L to other forcings, transient simulations of the last millennium are performed. Changes in solar irradiance, atmospheric greenhouse gas concentrations and volcanic emissions are applied to the model. The model is again broadly successful at simulating larger-scale changes in the

  7. Carbon Sequestration in Arable Soils is Likely to Increase Nitrous Oxide Emissions, Offsetting Reductions in Climate Radiative Forcing

    International Nuclear Information System (INIS)

    Li, Changsheng Li; Frolking, S.; Butterbach-Bahl, K.

    2005-01-01

    Strategies for mitigating the increasing concentration of carbon dioxide (CO2) in the atmosphere include sequestering carbon (C) in soils and vegetation of terrestrial ecosystems. Carbon and nitrogen (N) move through terrestrial ecosystems in coupled biogeochemical cycles, and increasing C stocks in soils and vegetation will have an impact on the N cycle. We conducted simulations with a biogeochemical model to evaluate the impact of different cropland management strategies on the coupled cycles of C and N, with special emphasis on C-sequestration and emission of the greenhouse gases methane (CH4) and nitrous oxide (N2O). Reduced tillage, enhanced crop residue incorporation, and farmyard manure application each increased soil C-sequestration, increased N2O emissions, and had little effect on CH4 uptake. Over 20 years, increases in N2O emissions, which were converted into CO2-equivalent emissions with 100-year global warming potential multipliers, offset 75-310% of the carbon sequestered, depending on the scenario. Quantification of these types of biogeochemical interactions must be incorporated into assessment frameworks and trading mechanisms to accurately evaluate the value of agricultural systems in strategies for climate protection

  8. Balancing atmospheric carbon dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Goreau, T.J. (Discovery Bay Marine Laboratory, Univ. of the West Indies (JM))

    1990-01-01

    Rising carbon dioxide and global temperatures are causing increasing worldwide concern, and pressure towards an international law of the atmosphere is rapidly escalating, yet widespread misconceptions about the greenhouse effect's inevitability, time scale, and causes have inhibited effective consensus and action. Observations from Antarctic ice cores, Amazonian rain forests, and Carribean coral reefs suggest that the biological effects of climate change may be more severe than climate models predict. Efforts to limit emissions from fossil-fuel combustion alone are incapable of stabilizing levels of carbon dioxide in the atmosphere. Stabilizing atmospheric carbon dioxide requires coupled measures to balance sources and sinks of the gas, and will only be viable with large-scale investments in increased sustainable productivity on degraded tropical soils, and in long-term research on renewable energy and biomass product development in the developing countries. A mechanism is outlined which directly links fossil-fuel combustion sources of carbon dioxide to removal via increasing biotic productivity and storage. A preliminary cost-benefit analysis suggests that such measures are very affordable, costing far less than inaction. (With 88 refs.).

  9. Balancing atmospheric carbon dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Goreau, T J [Discovery Bay Marine Laboratory, Univ. of the West Indies (JM)

    1990-01-01

    Rising carbon dioxide and global temperatures are causing increasing worldwide concern, and pressure towards an international law of the atmosphere is rapidly escalating, yet widespread misconceptions about the greenhouse effect's inevitability, time scale, and causes have inhibited effective consensus and action. Observations from Antarctic ice cores, Amazonian rain forests, and Carribean coral reefs suggest that the biological effects of climate change may be more severe than climate models predict. Efforts to limit emissions from fossil-fuel combustion alone are incapable of stabilizing levels of carbon dioxide in the atmosphere. Stabilizing atmospheric carbon dioxide requires coupled measures to balance sources and sinks of the gas, and will only be viable with large-scale investments in increased sustainable productivity on degraded tropical soils, and in long-term research on renewable energy and biomass product development in the developing countries. A mechanism is outlined which directly links fossil-fuel combustion sources of carbon dioxide to removal via increasing biotic productivity and storage. A preliminary cost-benefit analysis suggests that such measures are very affordable, costing far less than inaction. (With 88 refs.).

  10. Study of Radiative Forcing of Dust Aerosols and its impact on Climate Characteristics

    KAUST Repository

    Qureshi, Fawwad H

    2012-12-01

    The purpose of following project is to study the effect of dust aerosols on the radiative forcing which is directly related to the surface temperature. A single column radiative convective model is used for simulation purpose. A series of simulations have been performed by varying the amount of dust aerosols present in the atmosphere to study the trends in ground temperature, heating rate and radiative forcing for both its longwave and shortwave components. A case study for dust storm is also performed as dust storms are common in Arabian Peninsula. A sensitivity analyses is also performed to study the relationship of surface temperature minimum and maximum against aerosol concentration, single scattering albedo and asymmetry factor. These analyses are performed to get more insight into the role of dust aerosols on radiative forcing.

  11. Man -made greenhouse gases trigger unified force to start global warming impacts referred to as climate change

    International Nuclear Information System (INIS)

    Karishnan, K.J.; Kalam, A.

    2011-01-01

    Global warming problems due to man-made greenhouse gases (GHGs), appear to be a serious concern and threat to the globe. CO/sub 2/, O/sub 3, NOx and HFC's are the main greenhouse gases and CO/sub 2/ is one of the main cause of global warming. CO/sub 2/ is emitted from burning fossil fuels to produce electricity from power plants and burning of gasoline in vehicles and airplanes. Global greenhouse gases and its sources in regions are discussed in this paper. This paper initially discusses the CO/sub 2/ emissions and the recycle of CO/sub 2/ in biodiesel. This paper mainly focuses on 'Unified Force'. The increase of H/sub 2/O in the sea due to warming of the globe triggers the 'Unified Force' or 'Self-Compressive Surrounding Pressure Force' which is proportional to the H/sub 2/O level in the sea to start global warming impacts referred to as climate change. This paper also points out the climate change and the ten surprising results of global warming. Finally, this paper suggests switching from fossil fuel technology to green energy technologies like biodiesel which recycles CO/sub 2/ emissions and also Hydrogen Energy and Fuel Cell Technologies which eradicates global warming impacts. The benefits of switching from fossil fuel to biodiesel and Hydrogen Energy utilization includes reduction of greenhouse gas emissions and pollution, economic independence by having distributed production and burning of biodiesel does not add extra CO/sub 2/ to the air that contributes global warming impacts. (author)

  12. Modeling glacial climates

    Science.gov (United States)

    North, G. R.; Crowley, T. J.

    1984-01-01

    Mathematical climate modelling has matured as a discipline to the point that it is useful in paleoclimatology. As an example a new two dimensional energy balance model is described and applied to several problems of current interest. The model includes the seasonal cycle and the detailed land-sea geographical distribution. By examining the changes in the seasonal cycle when external perturbations are forced upon the climate system it is possible to construct hypotheses about the origin of midlatitude ice sheets and polar ice caps. In particular the model predicts a rather sudden potential for glaciation over large areas when the Earth's orbital elements are only slightly altered. Similarly, the drift of continents or the change of atmospheric carbon dioxide over geological time induces radical changes in continental ice cover. With the advance of computer technology and improved understanding of the individual components of the climate system, these ideas will be tested in far more realistic models in the near future.

  13. Geological and climatic forces driving speciation in the continentally distributed trilling chorus frogs (Pseudacris).

    Science.gov (United States)

    Lemmon, Emily Moriarty; Lemmon, Alan R; Cannatella, David C

    2007-09-01

    Tertiary geological events and Quaternary climatic fluctuations have been proposed as important factors of speciation in the North American flora and fauna. Few studies, however, have rigorously tested hypotheses regarding the specific factors driving divergence of taxa. Here, we test explicit speciation hypotheses by correlating geologic events with divergence times among species in the continentally distributed trilling chorus frogs (Pseudacris). In particular, we ask whether marine inundation of the Mississippi Embayment, uplift of the Appalachian Mountains, or modification of the ancient Teays-Mahomet River system contributed to speciation. To examine the plausibility of ancient rivers causing divergence, we tested whether modern river systems inhibit gene flow. Additionally, we compared the effects of Quaternary climatic factors (glaciation and aridification) on levels of genetic variation. Divergence time estimates using penalized likelihood and coalescent approaches indicate that the major lineages of chorus frogs diversified during the Tertiary, and also exclude Quaternary climate change as a factor in speciation of chorus frogs. We show the first evidence that inundation of the Mississippi Embayment contributed to speciation. We reject the hypotheses that Cenozoic uplift of the Appalachians and that diversion of the Teays-Mahomet River contributed to speciation in this clade. We find that by reducing gene flow, rivers have the potential to cause divergence of lineages. Finally, we demonstrate that populations in areas affected by Quaternary glaciation and aridification have reduced levels of genetic variation compared to those from more equable regions, suggesting recent colonization.

  14. Climate forcing and response to idealized changes in surface latent and sensible heat

    International Nuclear Information System (INIS)

    Ban-Weiss, George A; Cao Long; Pongratz, Julia; Caldeira, Ken; Bala, Govindasamy

    2011-01-01

    Land use and land cover changes affect the partitioning of latent and sensible heat, which impacts the broader climate system. Increased latent heat flux to the atmosphere has a local cooling influence known as 'evaporative cooling', but this energy will be released back to the atmosphere wherever the water condenses. However, the extent to which local evaporative cooling provides a global cooling influence has not been well characterized. Here, we perform a highly idealized set of climate model simulations aimed at understanding the effects that changes in the balance between surface sensible and latent heating have on the global climate system. We find that globally adding a uniform 1 W m -2 source of latent heat flux along with a uniform 1 W m -2 sink of sensible heat leads to a decrease in global mean surface air temperature of 0.54 ± 0.04 K. This occurs largely as a consequence of planetary albedo increases associated with an increase in low elevation cloudiness caused by increased evaporation. Thus, our model results indicate that, on average, when latent heating replaces sensible heating, global, and not merely local, surface temperatures decrease.

  15. The Flux-Anomaly-Forced Model Intercomparison Project (FAFMIP) Contribution to CMIP6: Investigation of Sea-Level and Ocean Climate Change in Response to CO2 Forcing

    Science.gov (United States)

    Gregory, Jonathan M.; Bouttes, Nathaelle; Griffies, Stephen M.; Haak, Helmuth; Hurlin, William J.; Jungclaus, Johann; Kelley, Maxwell; Lee, Warren G.; Marshall, John; Romanou, Anastasia; hide

    2016-01-01

    The Flux-Anomaly-Forced Model Intercomparison Project (FAFMIP) aims to investigate the spread in simulations of sea-level and ocean climate change in response to CO2 forcing by atmosphere-ocean general circulation models (AOGCMs). It is particularly motivated by the uncertainties in projections of ocean heat uptake, global-mean sealevel rise due to thermal expansion and the geographical patterns of sea-level change due to ocean density and circulation change. FAFMIP has three tier-1 experiments, in which prescribed surface flux perturbations of momentum, heat and freshwater respectively are applied to the ocean in separate AOGCM simulations. All other conditions are as in the pre-industrial control. The prescribed fields are typical of pattern and magnitude of changes in these fluxes projected by AOGCMs for doubled CO2 concentration. Five groups have tested the experimental design with existing AOGCMs. Their results show diversity in the pattern and magnitude of changes, with some common qualitative features. Heat and water flux perturbation cause the dipole in sea-level change in the North Atlantic, while momentum and heat flux perturbation cause the gradient across the Antarctic Circumpolar Current. The Atlantic meridional overturning circulation (AMOC) declines in response to the heat flux perturbation, and there is a strong positive feedback on this effect due to the consequent cooling of sea-surface temperature in the North Atlantic, which enhances the local heat input to the ocean. The momentum and water flux perturbations do not substantially affect the AMOC. Heat is taken up largely as a passive tracer in the Southern Ocean, which is the region of greatest heat input, while the weakening of the AMOC causes redistribution of heat towards lower latitudes. Future analysis of these and other phenomena with the wider range of CMIP6 FAFMIP AOGCMs will benefit from new diagnostics of temperature and salinity tendencies, which will enable investigation of the model

  16. Energy and climatic change

    International Nuclear Information System (INIS)

    Cadena, Angela Ines

    2000-01-01

    Human intervention in the carbon cycle has become a relevant concern in recent times. Global warming is a phenomenon due to the atmospheric concentration of greenhouse gases (GHG-s) carbon dioxide, methane, nitrous oxide and chlorofluorocarbons, believed to be irreversible. CO 2 is the most important GHG its contribution to the radioactive forcing of climate is estimated in about 70%. Changes in the global concentration of these gases depend on the level of emissions as a by-product of economic activities, the natural assimilative capacity of the global ecosystem, and the abatement activities. The paper include the Colombian situation

  17. Chemical and climatic drivers of radiative forcing due to changes in stratospheric and tropospheric ozone over the 21st century

    Directory of Open Access Journals (Sweden)

    A. Banerjee

    2018-02-01

    Full Text Available The ozone radiative forcings (RFs resulting from projected changes in climate, ozone-depleting substances (ODSs, non-methane ozone precursor emissions and methane between the years 2000 and 2100 are calculated using simulations from the UM-UKCA chemistry–climate model (UK Met Office's Unified Model containing the United Kingdom Chemistry and Aerosols sub-model. Projected measures to improve air-quality through reductions in non-methane tropospheric ozone precursor emissions present a co-benefit for climate, with a net global mean ozone RF of −0.09 W m−2. This is opposed by a positive ozone RF of 0.05 W m−2 due to future decreases in ODSs, which is driven by an increase in tropospheric ozone through stratosphere-to-troposphere transport of air containing higher ozone amounts. An increase in methane abundance by more than a factor of 2 (as projected by the RCP8.5 scenario is found to drive an ozone RF of 0.18 W m−2, which would greatly outweigh the climate benefits of non-methane tropospheric ozone precursor reductions. A small fraction (∼ 15 % of the ozone RF due to the projected increase in methane results from increases in stratospheric ozone. The sign of the ozone RF due to future changes in climate (including the radiative effects of greenhouse gases, sea surface temperatures and sea ice changes is shown to be dependent on the greenhouse gas emissions pathway, with a positive RF (0.05 W m−2 for RCP4.5 and a negative RF (−0.07 W m−2 for the RCP8.5 scenario. This dependence arises mainly from differences in the contribution to RF from stratospheric ozone changes. Considering the increases in tropopause height under climate change causes only small differences (≤ |0.02| W m−2 for the stratospheric, tropospheric and whole-atmosphere RFs.

  18. Climate Response to Negative Greenhouse Gas Radiative Forcing in Polar Winter

    Science.gov (United States)

    Flanner, M. G.; Huang, X.; Chen, X.; Krinner, G.

    2018-02-01

    Greenhouse gas (GHG) additions to Earth's atmosphere initially reduce global outgoing longwave radiation, thereby warming the planet. In select environments with temperature inversions, however, increased GHG concentrations can actually increase local outgoing longwave radiation. Negative top of atmosphere and effective radiative forcing (ERF) from this situation give the impression that local surface temperatures could cool in response to GHG increases. Here we consider an extreme scenario in which GHG concentrations are increased only within the warmest layers of winter near-surface inversions of the Arctic and Antarctic. We find, using a fully coupled Earth system model, that the underlying surface warms despite the GHG addition exerting negative ERF and cooling the troposphere in the vicinity of the GHG increase. This unique radiative forcing and thermal response is facilitated by the high stability of the polar winter atmosphere, which inhibit thermal mixing and amplify the impact of surface radiative forcing on surface temperature. These findings also suggest that strategies to exploit negative ERF via injections of short-lived GHGs into inversion layers would likely be unsuccessful in cooling the planetary surface.

  19. Global warming and climate forcing by recent albedo changes on Mars

    Science.gov (United States)

    Fenton, L.K.; Geissler, P.E.; Haberle, R.M.

    2007-01-01

    For hundreds of years, scientists have tracked the changing appearance of Mars, first by hand drawings and later by photographs. Because of this historical record, many classical albedo patterns have long been known to shift in appearance over time. Decadal variations of the martian surface albedo are generally attributed to removal and deposition of small amounts of relatively bright dust on the surface. Large swaths of the surface (up to 56 million km2) have been observed to darken or brighten by 10 per cent or more. It is unknown, however, how these albedo changes affect wind circulation, dust transport and the feedback between these processes and the martian climate. Here we present predictions from a Mars general circulation model, indicating that the observed interannual albedo alterations strongly influence the martian environment. Results indicate enhanced wind stress in recently darkened areas and decreased wind stress in brightened areas, producing a positive feedback system in which the albedo changes strengthen the winds that generate the changes. The simulations also predict a net annual global warming of surface air temperatures by ???0.65 K, enhancing dust lifting by increasing the likelihood of dust devil generation. The increase in global dust lifting by both wind stress and dust devils may affect the mechanisms that trigger large dust storm initiation, a poorly understood phenomenon, unique to Mars. In addition, predicted increases in summertime air temperatures at high southern latitudes would contribute to the rapid and steady scarp retreat that has been observed in the south polar residual ice for the past four Mars years. Our results suggest that documented albedo changes affect recent climate change and large-scale weather patterns on Mars, and thus albedo variations are a necessary component of future atmospheric and climate studies. ??2007 Nature Publishing Group.

  20. Water Security, Climate Forcings and Public Health Impacts in Emerging Regions

    Science.gov (United States)

    Serman, E. A.; Akanda, A. S.; Craver, V.; Boving, T. B.

    2014-12-01

    Our world is rapidly urbanizing, with more than 80% of world's population is expected to be living in a city by the end of the century. A majority of these nations are rapidly urbanizing due to massive rural-to-urban migratory trends, with rapid development of unplanned urban settlements, or slums, with lack of adequate water or sanitation facilities and other municipal amenities. With global environmental change, natural disasters will expose millions more to drought, floods, and disease epidemics, and existing vulnerabilities will worsen. At the same time, rapid urbanization and fast changing land-use leads to widespread damage of infrastructure by stormwater, especially in lowlands and economically poor areas. The factor that consistently stands out among different cities from both the developed and the developing worlds is that the slums are typically the most vulnerable to water related natural hazards and climatic threats, such as water scarcity and quality issues in drought conditions, or water and sanitation breakdown and stormwater contamination problems. Onsite or decentralized water, wastewater and stormwater treatment as well as point-of-use water treatment options can be an economic, safe, and reliable alternative to conventional large-scale treatment especially, in urban fringes as well as rural areas. These systems can be designed to fit communities in terms of their economic, cultural, environmental, and demographic resources. As part of this study, we develop a database of urban water quality and quantity indices such as with urban land-use, water usage, climate, and socio-economic characteristics in various emerging regions in the world. We analyze past and current data to identify and quantify long-term trends and the impacts of large-scale climatic and anthropogenic changes on urban hydrology and health impacts. We specifically focus on five major cities from distinct groups of countries and geographies: Providence, RI, USA from the developed

  1. Solar forcing of climate during the last millennium recorded in lake sediments from northern Sweden

    DEFF Research Database (Denmark)

    Kokfelt, Ulla; Muscheler, Raimund

    2013-01-01

    century. Periods of low solar activity are associated with minima in minerogenic material and vice versa. A comparison between the sunspot cycle and a long instrumental series of summer precipitation further reveals a link between the 11-year solar cycle and summer precipitation variability since around...... 1960. Solar minima are in this period associated with minima in summer precipitation, whereas the amount of summer precipitation increases during periods with higher solar activity. Our results suggest that the climate responds to both the 11-year solar cycle and to long-term changes in solar activity...... and in particular solar minima, causing dry conditions with resulting decreased runoff....

  2. Future discharge drought across climate regions around the world modelled with a synthetic hydrological modelling approach forced by three general circulation models

    Science.gov (United States)

    Wanders, N.; Van Lanen, H. A. J.

    2015-03-01

    Hydrological drought characteristics (drought in groundwater and streamflow) likely will change in the 21st century as a result of climate change. The magnitude and directionality of these changes and their dependency on climatology and catchment characteristics, however, is uncertain. In this study a conceptual hydrological model was forced by downscaled and bias-corrected outcome from three general circulation models for the SRES A2 emission scenario (GCM forced models), and the WATCH Forcing Data set (reference model). The threshold level method was applied to investigate drought occurrence, duration and severity. Results for the control period (1971-2000) show that the drought characteristics of each GCM forced model reasonably agree with the reference model for most of the climate types, suggesting that the climate models' results after post-processing produce realistic outcomes for global drought analyses. For the near future (2021-2050) and far future (2071-2100) the GCM forced models show a decrease in drought occurrence for all major climates around the world and increase of both average drought duration and deficit volume of the remaining drought events. The largest decrease in hydrological drought occurrence is expected in cold (D) climates where global warming results in a decreased length of the snow season and an increased precipitation. In the dry (B) climates the smallest decrease in drought occurrence is expected to occur, which probably will lead to even more severe water scarcity. However, in the extreme climate regions (desert and polar), the drought analysis for the control period showed that projections of hydrological drought characteristics are most uncertain. On a global scale the increase in hydrological drought duration and severity in multiple regions will lead to a higher impact of drought events, which should motivate water resource managers to timely anticipate the increased risk of more severe drought in groundwater and streamflow

  3. Relationship between sea level and climate forcing by CO2 on geological timescales.

    Science.gov (United States)

    Foster, Gavin L; Rohling, Eelco J

    2013-01-22

    On 10(3)- to 10(6)-year timescales, global sea level is determined largely by the volume of ice stored on land, which in turn largely reflects the thermal state of the Earth system. Here we use observations from five well-studied time slices covering the last 40 My to identify a well-defined and clearly sigmoidal relationship between atmospheric CO(2) and sea level on geological (near-equilibrium) timescales. This strongly supports the dominant role of CO(2) in determining Earth's climate on these timescales and suggests that other variables that influence long-term global climate (e.g., topography, ocean circulation) play a secondary role. The relationship between CO(2) and sea level we describe portrays the "likely" (68% probability) long-term sea-level response after Earth system adjustment over many centuries. Because it appears largely independent of other boundary condition changes, it also may provide useful long-range predictions of future sea level. For instance, with CO(2) stabilized at 400-450 ppm (as required for the frequently quoted "acceptable warming" of 2 °C), or even at AD 2011 levels of 392 ppm, we infer a likely (68% confidence) long-term sea-level rise of more than 9 m above the present. Therefore, our results imply that to avoid significantly elevated sea level in the long term, atmospheric CO(2) should be reduced to levels similar to those of preindustrial times.

  4. Modeling very large-fire occurrences over the continental United States from weather and climate forcing

    International Nuclear Information System (INIS)

    Barbero, R; Abatzoglou, J T; Steel, E A; K Larkin, Narasimhan

    2014-01-01

    Very large-fires (VLFs) have widespread impacts on ecosystems, air quality, fire suppression resources, and in many regions account for a majority of total area burned. Empirical generalized linear models of the largest fires (>5000 ha) across the contiguous United States (US) were developed at ∼60 km spatial and weekly temporal resolutions using solely atmospheric predictors. Climate−fire relationships on interannual timescales were evident, with wetter conditions than normal in the previous growing season enhancing VLFs probability in rangeland systems and with concurrent long-term drought enhancing VLFs probability in forested systems. Information at sub-seasonal timescales further refined these relationships, with short-term fire weather being a significant predictor in rangelands and fire danger indices linked to dead fuel moisture being a significant predictor in forested lands. Models demonstrated agreement in capturing the observed spatial and temporal variability including the interannual variability of VLF occurrences within most ecoregions. Furthermore the model captured the observed increase in VLF occurrences across parts of the southwestern and southeastern US from 1984 to 2010 suggesting that, irrespective of changes in fuels and land management, climatic factors have become more favorable for VLF occurrence over the past three decades in some regions. Our modeling framework provides a basis for simulations of future VLF occurrences from climate projections. (letter)

  5. The Greenhouse Effect and Climate Feedbacks

    Science.gov (United States)

    Covey, C.; Haberle, R. M.; McKay, C. P.; Titov, D. V.

    This chapter reviews the theory of the greenhouse effect and climate feedback. It also compares the theory with observations, using examples taken from all four known terrestrial worlds with substantial atmospheres: Venus, Earth, Mars, and Titan. The greenhouse effect traps infrared radiation in the atmosphere, thereby increasing surface temperature. It is one of many factors that affect a world's climate. (Others include solar luminosity and the atmospheric scattering and absorption of solar radiation.) A change in these factors — defined as climate forcing — may change the climate in a way that brings other processes — defined as feedbacks — into play. For example, when Earth's atmospheric carbon dioxide increases, warming the surface, the water vapor content of the atmosphere increases. This is a positive feedback on global warming because water vapor is itself a potent greenhouse gas. Many positive and negative feedback processes are significant in determining Earth's climate, and probably the climates of our terrestrial neighbors.

  6. Organic condensation: A vital link connecting aerosol formation to climate forcing (Invited)

    Science.gov (United States)

    Riipinen, I.; Pierce, J. R.; Yli-Juuti, T.; Nieminen, T.; Häkkinen, S.; Ehn, M.; Junninen, H.; Lehtipalo, K.; Petdjd, T. T.; Slowik, J. G.; Chang, R. Y.; Shantz, N. C.; Abbatt, J.; Leaitch, W. R.; Kerminen, V.; Worsnop, D. R.; Pandis, S. N.; Donahue, N. M.; Kulmala, M. T.

    2010-12-01

    Aerosol-cloud interactions represent the largest uncertainty in calculations of Earth’s radiative forcing. Number concentrations of atmospheric aerosol particles are in the core of this uncertainty, as they govern the numbers of cloud condensation nuclei (CCN) and influence the albedo and lifetime of clouds. Aerosols also impair air quality through their adverse effects on atmospheric visibility and human health. The ultrafine fraction ( 100 nm) and enhance the loss of ultrafine particles. Primary organic aerosol (POA) contributes to the large end of the aerosol size distribution, enhancing the scavenging of the ultrafine particles.

  7. The asymmetric evolution of the Colombian Eastern Cordillera. Tectonic inheritance or climatic forcing? New evidence from thermochronology and sedimentology

    Science.gov (United States)

    Ramirez-Arias, Juan Carlos; Mora, Andrés; Rubiano, Jorge; Duddy, Ian; Parra, Mauricio; Moreno, Nestor; Stockli, Daniel; Casallas, Wilson

    2012-11-01

    New thermochronological data, facies, paleocurrents and provenance allow us to refine the chronology of deformation in the central segment of the Colombian Eastern Cordillera. Based on a new extensive AFT dataset, we document the spatial evolution of active deformation, from the axial zone of the Eastern Cordillera at about 50 Ma in to active growth of the frontal thin skinned structures in Late Miocene time. Paleocurrents allow us to push backwards into the Middle to Early Late-Miocene the emergence of the easternmost frontal thrust; whereas careful assessment of exposure gates tied to AFT data enable to refine the unroofing history for Eocene to Miocene times. Based on that, we produced a kinematically restored cross section with higher resolution than previous assessments. Using these datasets, we compare the evolution of the central segment of the Eastern Cordillera in this region with the evolution of adjacent areas in the context of climatic forcing of orogenic evolution. We find that in this region and, in the Eastern Cordillera in general, tectonic inheritance and transpression exert an initial dominant control on the initial orogen asymmetry, which is later enhanced due to an orographically-focused erosion. We therefore suggest that it is not climate alone the factor controlling orogenic asymmetry in the Eastern Cordillera of Colombia.

  8. Climate

    International Nuclear Information System (INIS)

    Fellous, J.L.

    2005-02-01

    This book starts with a series of about 20 preconceived ideas about climate and climatic change and analyses each of them in the light of the present day knowledge. Using this approach, it makes a status of the reality of the climatic change, of its causes and of the measures to be implemented to limit its impacts and reduce its most harmful consequences. (J.S.)

  9. The large contribution of projected HFC emissions to future climate forcing.

    Science.gov (United States)

    Velders, Guus J M; Fahey, David W; Daniel, John S; McFarland, Mack; Andersen, Stephen O

    2009-07-07

    The consumption and emissions of hydrofluorocarbons (HFCs) are projected to increase substantially in the coming decades in response to regulation of ozone depleting gases under the Montreal Protocol. The projected increases result primarily from sustained growth in demand for refrigeration, air-conditioning (AC) and insulating foam products in developing countries assuming no new regulation of HFC consumption or emissions. New HFC scenarios are presented based on current hydrochlorofluorocarbon (HCFC) consumption in leading applications, patterns of replacements of HCFCs by HFCs in developed countries, and gross domestic product (GDP) growth. Global HFC emissions significantly exceed previous estimates after 2025 with developing country emissions as much as 800% greater than in developed countries in 2050. Global HFC emissions in 2050 are equivalent to 9-19% (CO(2)-eq. basis) of projected global CO(2) emissions in business-as-usual scenarios and contribute a radiative forcing equivalent to that from 6-13 years of CO(2) emissions near 2050. This percentage increases to 28-45% compared with projected CO(2) emissions in a 450-ppm CO(2) stabilization scenario. In a hypothetical scenario based on a global cap followed by 4% annual reductions in consumption, HFC radiative forcing is shown to peak and begin to decline before 2050.

  10. Historical versus contemporary climate forcing on the annual nesting variability of loggerhead sea turtles in the Northwest Atlantic Ocean.

    Directory of Open Access Journals (Sweden)

    Michael D Arendt

    Full Text Available A recent analysis suggested that historical climate forcing on the oceanic habitat of neonate sea turtles explained two-thirds of interannual variability in contemporary loggerhead (Caretta caretta sea turtle nest counts in Florida, where nearly 90% of all nesting by this species in the Northwest Atlantic Ocean occurs. Here, we show that associations between annual nest counts and climate conditions decades prior to nest counts and those conditions one year prior to nest counts were not significantly different. Examination of annual nest count and climate data revealed that statistical artifacts influenced the reported 31-year lag association with nest counts. The projected importance of age 31 neophytes to annual nest counts between 2020 and 2043 was modeled using observed nest counts between 1989 and 2012. Assuming consistent survival rates among cohorts for a 5% population growth trajectory and that one third of the mature female population nests annually, the 41% decline in annual nest counts observed during 1998-2007 was not projected for 2029-2038. This finding suggests that annual nest count trends are more influenced by remigrants than neophytes. Projections under the 5% population growth scenario also suggest that the Peninsular Recovery Unit could attain the demographic recovery criteria of 106,100 annual nests by 2027 if nest counts in 2019 are at least comparable to 2012. Because the first year of life represents only 4% of the time elapsed through age 31, cumulative survival at sea across decades explains most cohort variability, and thus, remigrant population size. Pursuant to the U.S. Endangered Species Act, staggered implementation of protection measures for all loggerhead life stages has taken place since the 1970s. We suggest that the 1998-2007 nesting decline represented a lagged perturbation response to historical anthropogenic impacts, and that subsequent nest count increases since 2008 reflect a potential recovery response.

  11. Sensitivity of Pliocene Arctic climate to orbital forcing, atmospheric CO2 and sea ice albedo parameterisation

    Science.gov (United States)

    Howell, Fergus W.; Haywood, Alan M.; Dowsett, Harry J.; Pickering, Steven J.

    2016-01-01

    General circulation model (GCM) simulations of the mid-Pliocene Warm Period (mPWP, 3.264 to 3.025 Myr ago) do not reproduce the magnitude of Northern Hemisphere high latitude surface air and sea surface temperature (SAT and SST) warming that proxy data indicate. There is also large uncertainty regarding the state of sea ice cover in the mPWP. Evidence for both perennial and seasonal mPWP Arctic sea ice is found through analyses of marine sediments, whilst in a multi-model ensemble of mPWP climate simulations, half of the ensemble simulated ice-free summer Arctic conditions. Given the strong influence that sea ice exerts on high latitude temperatures, an understanding of the nature of mPWP Arctic sea ice would be highly beneficial.

  12. A global classification of coastal flood hazard climates associated with large-scale oceanographic forcing.

    Science.gov (United States)

    Rueda, Ana; Vitousek, Sean; Camus, Paula; Tomás, Antonio; Espejo, Antonio; Losada, Inigo J; Barnard, Patrick L; Erikson, Li H; Ruggiero, Peter; Reguero, Borja G; Mendez, Fernando J

    2017-07-11

    Coastal communities throughout the world are exposed to numerous and increasing threats, such as coastal flooding and erosion, saltwater intrusion and wetland degradation. Here, we present the first global-scale analysis of the main drivers of coastal flooding due to large-scale oceanographic factors. Given the large dimensionality of the problem (e.g. spatiotemporal variability in flood magnitude and the relative influence of waves, tides and surge levels), we have performed a computer-based classification to identify geographical areas with homogeneous climates. Results show that 75% of coastal regions around the globe have the potential for very large flooding events with low probabilities (unbounded tails), 82% are tide-dominated, and almost 49% are highly susceptible to increases in flooding frequency due to sea-level rise.

  13. Equilibrium climate response of the East Asian summer monsoon to forcing of anthropogenic aerosol species

    Science.gov (United States)

    Wang, Zhili; Wang, Qiuyan; Zhang, Hua

    2017-12-01

    We used an online aerosol-climate model to study the equilibrium climate response of the East Asian summer monsoon (EASM) to increases in anthropogenic emissions of sulfate, organic carbon, and black carbon aerosols from 1850 to 2000. Our results show that each of these aerosol species has a different effect on the EASM as a result of changes in the local sea-land thermal contrast and atmospheric circulation. The increased emission of sulfate aerosol leads to a decrease in the thermal contrast between the land and ocean, a southward shift of the East Asian subtropical jet, and significant northerly wind anomalies at 850 hPa over eastern China and the ambient oceans, markedly dampening the EASM. An increase in organic carbon aerosol results in pronounced surface cooling and the formation of an anomalous anticyclone over the oceans north of 30°N. These effects cause a slight increase in the sea-land thermal contrast and southerly flow anomalies to the west of the anticyclonic center, strengthening the northern EASM. An increase in organic carbon emission decreases the sea-land thermal contrast over southern China, which weakens the southern EASM. The response of the summer 850-hPa winds and rainfall over the East Asian monsoon region to an increase in black carbon emission is generally consistent with the response to an increase in organic carbon. The increase in black carbon emission leads to a strengthening of the northern EASM north of 35°N and a slight weakening of the southern EASM south of 35°N. The simulated response of the EASM to the increase in black carbon emission is unchanged when the emission of black carbon is scaled up by five times its year 2000 levels, although the intensities of the response is enhanced. The increase in sulfate emission primarily weakens the EASM, whereas the increases in black carbon and organic carbon emissions mitigate weakening of the northern EASM.

  14. Vertical microphysical profiles of convective clouds as a tool for obtaining aerosol cloud-mediated climate forcings

    Energy Technology Data Exchange (ETDEWEB)

    Rosenfeld, Daniel [Hebrew Univ. of Jerusalem (Israel)

    2015-12-23

    Quantifying the aerosol/cloud-mediated radiative effect at a global scale requires simultaneous satellite retrievals of cloud condensation nuclei (CCN) concentrations and cloud base updraft velocities (Wb). Hitherto, the inability to do so has been a major cause of high uncertainty regarding anthropogenic aerosol/cloud-mediated radiative forcing. This can be addressed by the emerging capability of estimating CCN and Wb of boundary layer convective clouds from an operational polar orbiting weather satellite. Our methodology uses such clouds as an effective analog for CCN chambers. The cloud base supersaturation (S) is determined by Wb and the satellite-retrieved cloud base drop concentrations (Ndb), which is the same as CCN(S). Developing and validating this methodology was possible thanks to the ASR/ARM measurements of CCN and vertical updraft profiles. Validation against ground-based CCN instruments at the ARM sites in Oklahoma, Manaus, and onboard a ship in the northeast Pacific showed a retrieval accuracy of ±25% to ±30% for individual satellite overpasses. The methodology is presently limited to boundary layer not raining convective clouds of at least 1 km depth that are not obscured by upper layer clouds, including semitransparent cirrus. The limitation for small solar backscattering angles of <25º restricts the satellite coverage to ~25% of the world area in a single day. This methodology will likely allow overcoming the challenge of quantifying the aerosol indirect effect and facilitate a substantial reduction of the uncertainty in anthropogenic climate forcing.

  15. The Flux-Anomaly-Forced Model Intercomparison Project (FAFMIP contribution to CMIP6: investigation of sea-level and ocean climate change in response to CO2 forcing

    Directory of Open Access Journals (Sweden)

    J. M. Gregory

    2016-11-01

    Full Text Available The Flux-Anomaly-Forced Model Intercomparison Project (FAFMIP aims to investigate the spread in simulations of sea-level and ocean climate change in response to CO2 forcing by atmosphere–ocean general circulation models (AOGCMs. It is particularly motivated by the uncertainties in projections of ocean heat uptake, global-mean sea-level rise due to thermal expansion and the geographical patterns of sea-level change due to ocean density and circulation change. FAFMIP has three tier-1 experiments, in which prescribed surface flux perturbations of momentum, heat and freshwater respectively are applied to the ocean in separate AOGCM simulations. All other conditions are as in the pre-industrial control. The prescribed fields are typical of pattern and magnitude of changes in these fluxes projected by AOGCMs for doubled CO2 concentration. Five groups have tested the experimental design with existing AOGCMs. Their results show diversity in the pattern and magnitude of changes, with some common qualitative features. Heat and water flux perturbation cause the dipole in sea-level change in the North Atlantic, while momentum and heat flux perturbation cause the gradient across the Antarctic Circumpolar Current. The Atlantic meridional overturning circulation (AMOC declines in response to the heat flux perturbation, and there is a strong positive feedback on this effect due to the consequent cooling of sea-surface temperature in the North Atlantic, which enhances the local heat input to the ocean. The momentum and water flux perturbations do not substantially affect the AMOC. Heat is taken up largely as a passive tracer in the Southern Ocean, which is the region of greatest heat input, while the weakening of the AMOC causes redistribution of heat towards lower latitudes. Future analysis of these and other phenomena with the wider range of CMIP6 FAFMIP AOGCMs will benefit from new diagnostics of temperature and salinity tendencies, which will enable

  16. Sensitivity of wetland hydrology to external climate forcing in central Florida

    Science.gov (United States)

    Lammertsma, Emmy I.; Donders, Timme H.; Pearce, Christof; Cremer, Holger; Gaiser, Evelyn E.; Wagner-Cremer, Friederike

    2015-11-01

    Available proxy records from the Florida peninsula give a varying view on hydrological changes during the late Holocene. Here we evaluate the consistency and sensitivity of local wetland records in relation to hydrological changes over the past 5 ka based on pollen and diatom proxies from peat cores in Highlands Hammock State Park, central Florida. Around 5 cal ka BP, a dynamic floodplain environment is present. Subsequently, a wetland forest establishes, followed by a change to persistent wet conditions between 2.5 and 2.0 ka. Long hydroperiods remain despite gradual succession and basin infilling with maximum wet conditions between 1.3 and 1.0 ka. The wet phase and subsequent strong drying over the last millennium, as indicated by shifts in both pollen and diatom assemblages, can be linked to the early Medieval Warm Period and Little Ice Age, respectively, driven by regionally higher sea-surface temperatures and a temporary northward migration of the Intertropical Convergence Zone. Changes during the 20th century are the result of constructions intended to protect the Highlands Hammock State Park from wildfires. The multiple cores and proxies allow distinguishing local and regional hydrological changes. The peat records reflect relatively subtle climatic changes that are not evident from regional pollen records from lakes.

  17. Weak Hydrological Sensitivity to Temperature Change over Land, Independent of Climate Forcing

    Science.gov (United States)

    Samset, B. H.; Myhre, G.; Forster, P. M.; Hodnebrog, O.; Andrews, T.; Boucher, O.; Faluvegi, G.; Flaeschner, D.; Kasoar, M.; Kharin, V.; hide

    2018-01-01

    We present the global and regional hydrological sensitivity (HS) to surface temperature changes, for perturbations to CO2, CH4, sulfate and black carbon concentrations, and solar irradiance. Based on results from ten climate models, we show how modeled global mean precipitation increases by 2-3% per kelvin of global mean surface warming, independent of driver, when the effects of rapid adjustments are removed. Previously reported differences in response between drivers are therefore mainly ascribable to rapid atmospheric adjustment processes. All models show a sharp contrast in behavior over land and over ocean, with a strong surface temperature-driven (slow) ocean HS of 3-5%/K, while the slow land HS is only 0-2%/K. Separating the response into convective and large-scale cloud processes, we find larger inter-model differences, in particular over land regions. Large-scale precipitation changes are most relevant at high latitudes, while the equatorial HS is dominated by convective precipitation changes. Black carbon stands out as the driver with the largest inter-model slow HS variability, and also the strongest contrast between a weak land and strong sea response. We identify a particular need for model investigations and observational constraints on convective precipitation in the Arctic, and large-scale precipitation around the Equator.

  18. Tropospheric ozone changes, radiative forcing and attribution to emissions in the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP

    Directory of Open Access Journals (Sweden)

    D. S. Stevenson

    2013-03-01

    Full Text Available Ozone (O3 from 17 atmospheric chemistry models taking part in the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP has been used to calculate tropospheric ozone radiative forcings (RFs. All models applied a common set of anthropogenic emissions, which are better constrained for the present-day than the past. Future anthropogenic emissions follow the four Representative Concentration Pathway (RCP scenarios, which define a relatively narrow range of possible air pollution emissions. We calculate a value for the pre-industrial (1750 to present-day (2010 tropospheric ozone RF of 410 mW m−2. The model range of pre-industrial to present-day changes in O3 produces a spread (±1 standard deviation in RFs of ±17%. Three different radiation schemes were used – we find differences in RFs between schemes (for the same ozone fields of ±10%. Applying two different tropopause definitions gives differences in RFs of ±3%. Given additional (unquantified uncertainties associated with emissions, climate-chemistry interactions and land-use change, we estimate an overall uncertainty of ±30% for the tropospheric ozone RF. Experiments carried out by a subset of six models attribute tropospheric ozone RF to increased emissions of methane (44±12%, nitrogen oxides (31 ± 9%, carbon monoxide (15 ± 3% and non-methane volatile organic compounds (9 ± 2%; earlier studies attributed more of the tropospheric ozone RF to methane and less to nitrogen oxides. Normalising RFs to changes in tropospheric column ozone, we find a global mean normalised RF of 42 mW m−2 DU−1, a value similar to previous work. Using normalised RFs and future tropospheric column ozone projections we calculate future tropospheric ozone RFs (mW m−2; relative to 1750 for the four future scenarios (RCP2.6, RCP4.5, RCP6.0 and RCP8.5 of 350, 420, 370 and 460 (in 2030, and 200, 300, 280 and 600 (in 2100. Models show some coherent responses of ozone to climate change

  19. Future climate and surface mass balance of Svalbard glaciers in an RCP8.5 climate scenario: a study with the regional climate model MAR forced by MIROC5

    Science.gov (United States)

    Lang, C.; Fettweis, X.; Erpicum, M.

    2015-05-01

    We have performed a future projection of the climate and surface mass balance (SMB) of Svalbard with the MAR (Modèle Atmosphérique Régional) regional climate model forced by MIROC5 (Model for Interdisciplinary Research on Climate), following the RCP8.5 scenario at a spatial resolution of 10 km. MAR predicts a similar evolution of increasing surface melt everywhere in Svalbard followed by a sudden acceleration of melt around 2050, with a larger melt increase in the south compared to the north of the archipelago. This melt acceleration around 2050 is mainly driven by the albedo-melt feedback associated with the expansion of the ablation/bare ice zone. This effect is dampened in part as the solar radiation itself is projected to decrease due to a cloudiness increase. The near-surface temperature is projected to increase more in winter than in summer as the temperature is already close to 0 °C in summer. The model also projects a stronger winter west-to-east temperature gradient, related to the large decrease of sea ice cover around Svalbard. By 2085, SMB is projected to become negative over all of Svalbard's glaciated regions, leading to the rapid degradation of the firn layer.

  20. Responses of stream nitrate and DOC loadings to hydrological forcing and climate change in an upland forest of the northeastern United States

    Science.gov (United States)

    Stephen D. Sebestyen; Elizabeth W. Boyer; James B. Shanley

    2009-01-01

    In coming decades, higher annual temperatures, increased growing season length, and increased dormant season precipitation are expected across the northeastern United States in response to anthropogenic forcing of global climate. We synthesized long-term stream hydrochemical data from the Sleepers River Research Watershed in Vermont, United States, to explore the...

  1. Importance of Preserving Cross-correlation in developing Statistically Downscaled Climate Forcings and in estimating Land-surface Fluxes and States

    Science.gov (United States)

    Das Bhowmik, R.; Arumugam, S.

    2015-12-01

    Multivariate downscaling techniques exhibited superiority over univariate regression schemes in terms of preserving cross-correlations between multiple variables- precipitation and temperature - from GCMs. This study focuses on two aspects: (a) develop an analytical solutions on estimating biases in cross-correlations from univariate downscaling approaches and (b) quantify the uncertainty in land-surface states and fluxes due to biases in cross-correlations in downscaled climate forcings. Both these aspects are evaluated using climate forcings available from both historical climate simulations and CMIP5 hindcasts over the entire US. The analytical solution basically relates the univariate regression parameters, co-efficient of determination of regression and the co-variance ratio between GCM and downscaled values. The analytical solutions are compared with the downscaled univariate forcings by choosing the desired p-value (Type-1 error) in preserving the observed cross-correlation. . For quantifying the impacts of biases on cross-correlation on estimating streamflow and groundwater, we corrupt the downscaled climate forcings with different cross-correlation structure.

  2. Carbon dioxide flux and net primary production of a boreal treed bog: Responses to warming and water-table-lowering simulations of climate change

    Science.gov (United States)

    Munir, T. M.; Perkins, M.; Kaing, E.; Strack, M.

    2015-02-01

    Midlatitude treed bogs represent significant carbon (C) stocks and are highly sensitive to global climate change. In a dry continental treed bog, we compared three sites: control, recent (1-3 years; experimental) and older drained (10-13 years), with water levels at 38, 74 and 120 cm below the surface, respectively. At each site we measured carbon dioxide (CO2) fluxes and estimated tree root respiration (Rr; across hummock-hollow microtopography of the forest floor) and net primary production (NPP) of trees during the growing seasons (May to October) of 2011-2013. The CO2-C balance was calculated by adding the net CO2 exchange of the forest floor (NEff-Rr) to the NPP of the trees. From cooler and wetter 2011 to the driest and the warmest 2013, the control site was a CO2-C sink of 92, 70 and 76 g m-2, the experimental site was a CO2-C source of 14, 57 and 135 g m-2, and the drained site was a progressively smaller source of 26, 23 and 13 g CO2-C m-2. The short-term drainage at the experimental site resulted in small changes in vegetation coverage and large net CO2 emissions at the microforms. In contrast, the longer-term drainage and deeper water level at the drained site resulted in the replacement of mosses with vascular plants (shrubs) on the hummocks and lichen in the hollows leading to the highest CO2 uptake at the drained hummocks and significant losses in the hollows. The tree NPP (including above- and below-ground growth and litter fall) in 2011 and 2012 was significantly higher at the drained site (92 and 83 g C m-2) than at the experimental (58 and 55 g C m-2) and control (52 and 46 g C m-2) sites. We also quantified the impact of climatic warming at all water table treatments by equipping additional plots with open-top chambers (OTCs) that caused a passive warming on average of ~ 1 °C and differential air warming of ~ 6 °C at midday full sun over the study years. Warming significantly enhanced shrub growth and the CO2 sink function of the drained

  3. Progress report of the Interagency Climate Change Adaptation Task Force : recommended actions in support of a national climate change adaptation strategy

    Science.gov (United States)

    2010-10-05

    The scope, severity, and pace of : future climate change impacts are : difficult to predict. However, : observations and long-term scientific : trends indicate that the potential : impacts of a changing climate on : society and the environment will b...

  4. On Effective Radiative Forcing of Partial Internally and Externally Mixed Aerosols and Their Effects on Global Climate

    Science.gov (United States)

    Zhou, Chen; Zhang, Hua; Zhao, Shuyun; Li, Jiangnan

    2018-01-01

    The total effective radiative forcing (ERF) due to partial internally mixed (PIM) and externally mixed (EM) anthropogenic aerosols, as well as their climatic effects since the year of 1850, was evaluated and compared using the aerosol-climate online coupled model of BCC_AGCM2.0_CUACE/Aero. The influences of internal mixing (IM) on aerosol hygroscopicity parameter, optical properties, and concentration were considered. Generally, IM could markedly weaken the negative ERF and cooling effects of anthropogenic aerosols. The global annual mean ERF of EM anthropogenic aerosols from 1850 to 2010 was -1.87 W m-2, of which the aerosol-radiation interactive ERF (ERFari) and aerosol-cloud interactive ERF (ERFaci) were -0.49 and -1.38 W m-2, respectively. The global annual mean ERF due to PIM anthropogenic aerosols from 1850 to 2010 was -1.23 W m-2, with ERFari and ERFaci of -0.23 and -1.01 W m-2, respectively. The global annual mean surface temperature and water evaporation and precipitation were reduced by 1.74 K and 0.14 mm d-1 for EM scheme and 1.28 K and 0.11 mm d-1 for PIM scheme, respectively. However, the relative humidity near the surface was slightly increased for both mixing cases. The Intertropical Convergence Zone was southwardly shifted for both EM and PIM cases but was less southwardly shifted in PIM scheme due to the less reduction in atmospheric temperature in the midlatitude and low latitude of the Northern Hemisphere.

  5. Carbon dioxide: emissions and effects

    Energy Technology Data Exchange (ETDEWEB)

    Smith, I M

    1982-01-01

    This review provides a comprehensive guide to work carried out since 1978 in the many disciplines involved in this complex issue. Possible scenarios for carbon dioxide emissions, sources and sinks in the carbon cycle and for climatic changes are examined. The current concensus (by no means unanimous) of specialists on this issue appears to be that a continuation of reduced trends in energy consumption since 1973 is likely to double the atmospheric carbon dioxide concentration to 600 ppmv during the latter part of the next century. However, a higher demand scenario, requiring an upper limit of coal production, would bring forward the doubling to about the middle of the next century. Current climatic models predict that such a concentration of carbon dioxide would cause an average global warming of from 1.0 to 4.5/sup 0/C which might be delayed by the thermal inertia of the oceans. A warming due to estimated increases in carbon dioxide should, if the model results are correct, become apparent at the end of this century. Regional climatic changes are likely to vary considerably and prove disadvantageous to some regions and beneficial to others. Different strategies for dealing with the carbon dioxide issue are considered: no response, alleviation, countermeasures and prevention. It is concluded that uncertainties do not justify either the use of carbon dioxide disposal and other technical fixes at present or a policy of no further growth in fossil fuel consumption. On the other hand, major efforts to conserve energy would give more time to adapt to changes. The alleviation of climatic impacts and other desirable dual-benefit measures are advocated in addition to continuing international, interdisciplinary research on all aspects.

  6. Particulate sulfur in the upper troposphere and lowermost stratosphere – sources and climate forcing

    Directory of Open Access Journals (Sweden)

    B. G. Martinsson

    2017-09-01

    Full Text Available This study is based on fine-mode aerosol samples collected in the upper troposphere (UT and the lowermost stratosphere (LMS of the Northern Hemisphere extratropics during monthly intercontinental flights at 8.8–12 km altitude of the IAGOS-CARIBIC platform in the time period 1999–2014. The samples were analyzed for a large number of chemical elements using the accelerator-based methods PIXE (particle-induced X-ray emission and PESA (particle elastic scattering analysis. Here the particulate sulfur concentrations, obtained by PIXE analysis, are investigated. In addition, the satellite-borne lidar aboard CALIPSO is used to study the stratospheric aerosol load. A steep gradient in particulate sulfur concentration extends several kilometers into the LMS, as a result of increasing dilution towards the tropopause of stratospheric, particulate sulfur-rich air. The stratospheric air is diluted with tropospheric air, forming the extratropical transition layer (ExTL. Observed concentrations are related to the distance to the dynamical tropopause. A linear regression methodology handled seasonal variation and impact from volcanism. This was used to convert each data point into stand-alone estimates of a concentration profile and column concentration of particulate sulfur in a 3 km altitude band above the tropopause. We find distinct responses to volcanic eruptions, and that this layer in the LMS has a significant contribution to the stratospheric aerosol optical depth and thus to its radiative forcing. Further, the origin of UT particulate sulfur shows strong seasonal variation. We find that tropospheric sources dominate during the fall as a result of downward transport of the Asian tropopause aerosol layer (ATAL formed in the Asian monsoon, whereas transport down from the Junge layer is the main source of UT particulate sulfur in the first half of the year. In this latter part of the year, the stratosphere is the clearly dominating source of

  7. Global distribution and climate forcing of marine organic aerosol: 1. Model improvements and evaluation

    Directory of Open Access Journals (Sweden)

    N. Meskhidze

    2011-11-01

    marine organics are internally-mixed with sea-salt provides diverse results with increases and decreases in the concentration of CCN over different parts of the ocean. The sign of the CCN change due to the addition of marine organics to sea-salt aerosol is determined by the relative significance of the increase in mean modal diameter due to addition of mass, and the decrease in particle hygroscopicity due to compositional changes in marine aerosol. Based on emerging evidence for increased CCN concentration over biologically active surface ocean areas/periods, our study suggests that treatment of sea spray in global climate models (GCMs as an internal mixture of marine organic aerosols and sea-salt will likely lead to an underestimation in CCN number concentration.

  8. A role for land surface forcing of North Atlantic climate and isotope signals during the 8.2kyr event?

    Science.gov (United States)

    Hopcroft, Peter; Valdes, Paul

    2014-05-01

    An important example of abrupt climate change occurred 8200 years ago in the North Atlantic and is generally known as the 8.2kyr event. This abrupt ~160 year cooling appears to coincide with the final drainage of the ice-dammed Lakes Agassiz and Ojibway. The resultant influx of meltwater to the North Atlantic is assumed to have perturbed the Atlantic Meridional Overturning circulation, reducing northward heat transport and causing widespread cooling. Numerous lines of evidence support this theory, with reconstructions showing changes in deep water formation, reductions in salinity and evidence of sea-level rise. Coupled general circulation model (GCM) simulations driven with realistic estimates of the meltwater flux show a regional cooling but fail to replicate the duration or the magnitude of this event in comparison with proxy archives. Meltwater injection was not the only rapid climate forcing in operation at this time. Drainage of the pro-glacial lakes would have had a profound effect on the boundary layer heat fluxes over North America, with potential teleconnections further afield. In this work we use an isotope-enabled version of the coupled GCM HadCM3 with boundary conditions appropriate for the time period of 9kyr (including ice sheets, greenhouse gases and orbital parameters). This model tracks oxygen isotopes throughout the hydrological cycle allowing more robust comparison with proxy archives. We analyse the impact of the removal of a lake area corresponding to Lakes Agassiz and Ojibway at this time and present sensitivity tests designed to analyse the contributions from lake removal, orographic change and the assumed isotopic content of the pro-glacial lakes. The results show a distinct pattern of cooling across North America (in the annual mean) with an apparent teleconnection to the Barents Sea, where there is warming associated with sea-ice reduction. The isotopic implications depend on the initial isotopic content of the pro-glacial lake. Assuming

  9. Detection of greenhouse-gas-induced climatic change

    International Nuclear Information System (INIS)

    Wigley, T.M.L.; Jones, P.D.

    1992-01-01

    The aims of the US Department of Energy's Carbon Dioxide Research Program are to improve assessments of greenhouse-gas-induced climatic change and to define and reduce uncertainties through selected research. This project will address: The regional and seasonal details of the expected climatic changes; how rapidly will these changes occur; how and when will the climatic effects of CO 2 and other greenhouse gases be first detected; and the relationships between greenhouse-gas-induced climatic change and changes caused by other external and internal factors. The present project addresses all of these questions. Many of the diverse facets of greenhouse-gas-related climate research can be grouped under three interlinked subject areas: modeling, first detection and supporting data. This project will include the analysis of climate forcing factors, the development and refinement of transient response climate models, and the use of instrumental data in validating General Circulation Models (GCMs)

  10. Recent climate warming forces contrasting growth responses of white spruce at treeline in Alaska through temperature thresholds

    Science.gov (United States)

    Martin Wilmking; Glenn P. Juday; Valerie A. Barber; Harold S.J. Zald

    2004-01-01

    Northern and high-latitude alpine treelines are generally thought to be limited by available warmth. Most studies of tree-growth-climate interaction at treeline as well as climate reconstructions using dendrochronology report positive growth response of treeline trees to warmer temperatures. However, population-wide responses of treeline trees to climate remain largely...

  11. Fluxes of Methane and Carbon Dioxide from a Subarctic Lake

    DEFF Research Database (Denmark)

    Jammet, Mathilde Manon

    ) and carbon dioxide (CO2) with the atmosphere. Yet uncertainties in the magnitude and drivers of these fluxes remain, partly due to a lack of direct observations covering all seasons of the year, but also because of the diversity in measurement methods that often miss components of the transport processes......Ongoing climate warming is expected to affect the carbon functioning of subarctic ecosystems. Lakes and wetlands, which are common ecosystems of the high northern latitudes, are of utmost interest in this context because they exchange large amounts of the climate-forcing gases methane (CH4......-out and the release of CH4 and CO2 was established. These results underline the crucial importance of shoulder seasons in the annual carbon emissions from seasonally frozen lakes. Overall, the lake was an important annual source of carbon to the atmosphere, partially compensating the higher, annual sink function...

  12. Influence of shear forces on the aggregation and sedimentation behavior of cerium dioxide (CeO{sub 2}) nanoparticles under different hydrochemical conditions

    Energy Technology Data Exchange (ETDEWEB)

    Lv, Bowen; Wang, Chao; Hou, Jun, E-mail: hhuhjyhj@126.com; Wang, Peifang, E-mail: pfwang2005@hhu.edu.cn; Miao, Lingzhan; Li, Yi; Ao, Yanhui; Yang, Yangyang; You, Guoxiang; Xu, Yi [Hohai University, Key Laboratory of Integrated Regulation and Resources Development on Shallow Lakes, Ministry of Education (China)

    2016-07-15

    This study contributed to a better understanding of the behavior of nanoparticles (NPs) in dynamic water. First, the aggregation behavior of CeO{sub 2} NPs at different pH values in various salt solutions was examined to determine the appropriate hydrochemical conditions for hydrodynamics study. Second, the aggregation behavior of CeO{sub 2} NPs under different shear forces was investigated at pH 4 and ionic strength 0 in various salt solutions to find out whether shear forces could influence the stability of the nanoparticles and if yes, how. Also, five-stage sedimentation tests were conducted to understand the influence of shear stress on the vertical distribution of CeO{sub 2} NPs in natural waters. The aggregation test showed that the shear force could increase the collision efficiency between NPs during aggregation and cause a relatively large mass of NPs to remain in suspension. Consequently, the nanoparticles had a greater possibility of continued aggregation. The sedimentation test under static conditions indicated that a large mass of NPs (>1000 nm) sink to the bottom layer, leaving only small aggregates dispersed in the upper or middle layer of the solution. However, later sedimentation studies under stirring conditions demonstrated that shear forces can disrupt this stratification phenomenon. These results suggest that shear forces can influence the spatial distribution of NPs in natural waters, which might lead to different toxicities of CeO{sub 2} NPs to aquatic organisms distributed in the different water layers. This study contributes to a better understanding of nanomaterial toxicology and provides a way for further research.Graphical Abstract.

  13. Local Climate Changes Forced by Changes in Land Use and topography in the Aburrá Valley, Colombia.

    Science.gov (United States)

    Zapata Henao, M. Z.; Hoyos Ortiz, C. D.

    2017-12-01

    One of the challenges in the numerical weather models is the adequate representation of soil-vegetation-atmosphere interaction at different spatial scales, including scenarios with heterogeneous land cover and complex mountainous terrain. The interaction determines the energy, mass and momentum exchange at the surface and could affect different variables including precipitation, temperature and wind. In order to quantify the long-term climate impact of changes in local land use and to assess the role of topography, two numerical experiments were examined. The first experiment allows assessing the continuous growth of urban areas within the Aburrá Valley, a complex terrain region located in Colombian Andes. The Weather Research Forecast model (WRF) is used as the basis of the experiment. The basic setup involves two nested domains, one representing the continental scale (18 km) and the other the regional scale (2 km). The second experiment allows drastic topography modification, including changing the valley configuration to a plateau. The control run for both experiments corresponds to a climatological scenario. In both experiments the boundary conditions correspond to the climatological continental domain output. Surface temperature, surface winds and precipitation are used as the main variables to compare both experiments relative to the control run. The results of the first experiment show a strong relationship between land cover and the variables, specially for surface temperature and wind speed, due to the strong forcing land cover imposes on the albedo, heat capacity and surface roughness, changing temperature and wind speed magnitudes. The second experiment removes the winds spatial variability related with hill slopes, the direction and magnitude are modulated only by the trade winds and roughness of land cover.

  14. Environmental effects of increased atmospheric carbon dioxide

    International Nuclear Information System (INIS)

    Soon, W.; Baliunas, S.L.; Robinson, A.B.; Robinson, Z.W.

    1999-01-01

    A review of the literature concerning the environmental consequences of increased levels of atmospheric carbon dioxide leads to the conclusion that increases during the 20th century have produced no deleterious effects upon global climate or temperature. Increased carbon dioxide has, however, markedly increased plant growth rates as inferred from numerous laboratory and field experiments. There is no clear evidence, nor unique attribution, of the global effects of anthropogenic CO 2 on climate. Meaningful integrated assessments of the environmental impacts of anthropogenic CO 2 are not yet possible because model estimates of global and regional climate changes on interannual, decadal and centennial timescales remain highly uncertain.(author)

  15. Statistical framework for evaluation of climate model simulations by use of climate proxy data from the last millennium – Part 2: A pseudo-proxy study addressing the amplitude of solar forcing

    Directory of Open Access Journals (Sweden)

    A. Hind

    2012-08-01

    Full Text Available The statistical framework of Part 1 (Sundberg et al., 2012, for comparing ensemble simulation surface temperature output with temperature proxy and instrumental records, is implemented in a pseudo-proxy experiment. A set of previously published millennial forced simulations (Max Planck Institute – COSMOS, including both "low" and "high" solar radiative forcing histories together with other important forcings, was used to define "true" target temperatures as well as pseudo-proxy and pseudo-instrumental series. In a global land-only experiment, using annual mean temperatures at a 30-yr time resolution with realistic proxy noise levels, it was found that the low and high solar full-forcing simulations could be distinguished. In an additional experiment, where pseudo-proxies were created to reflect a current set of proxy locations and noise levels, the low and high solar forcing simulations could only be distinguished when the latter served as targets. To improve detectability of the low solar simulations, increasing the signal-to-noise ratio in local temperature proxies was more efficient than increasing the spatial coverage of the proxy network. The experiences gained here will be of guidance when these methods are applied to real proxy and instrumental data, for example when the aim is to distinguish which of the alternative solar forcing histories is most compatible with the observed/reconstructed climate.

  16. Potential forcing of CO2, technology and climate changes in maize (Zea mays) and bean (Phaseolus vulgaris) yield in southeast Brazil

    International Nuclear Information System (INIS)

    Costa, L C; Justino, F; Oliveira, L J C; Sediyama, G C; Lemos, C F; Ferreira, W P M

    2009-01-01

    Based upon sensitivity experiments, this study aims to investigate the impact of increased atmospheric CO 2 concentration, climate changes, and ongoing technological advancements on bean (Phaseolus vulgaris) and maize (Zea mays) yield. This investigation assumes that the atmospheric CO 2 concentration evolves according to the A2 scenario. For these analyses we have used climate data as projected by climate simulations conducted with the HadCM3 climate model for both present day and greenhouse warming conditions. The results demonstrated that warming conditions associated with increased greenhouse gases as delivered by the HadCM3 model lead to reductions in the potential productivity of maize and beans for the years 2050 and 2080 by up to 30%. This thermal response is, however, damped by the highly efficient CO 2 fertilization effect which is expected to increase bean productivity as compared to present day conditions. A similar investigation for maize yield revealed a different picture. It has been found that the CO 2 fertilization feedback is much weaker and cannot cancel out the thermal effect. We have found, therefore, that climate changes as simulated to occur in the future are not favorable for increasing the maize yield in southeast Brazil. By the inclusion of the third forcing evaluated, representing technological advancements, it is demonstrated that improvements in the crop system reduce the negative effect associated with warmer climate conditions for both crops. We conclude that appropriate soil and technological management as well as genetic improvements may very likely induce an increase in bean and maize yield despite the unfavorable future climate conditions.

  17. Potential forcing of CO{sub 2}, technology and climate changes in maize (Zea mays) and bean (Phaseolus vulgaris) yield in southeast Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Costa, L C; Justino, F; Oliveira, L J C; Sediyama, G C; Lemos, C F [Department of Agricultural Engineering, Federal University of Vicosa, PH Rolfs S/N, Vicosa, MG, 36570 000 (Brazil); Ferreira, W P M [Embrapa Milho e Sorgo, Rodovia MG 424, km 45, Caixa Postal 285, CEP 35701-970 Sete Lagoas, MG (Brazil)], E-mail: fjustino@ufv.br

    2009-01-15

    Based upon sensitivity experiments, this study aims to investigate the impact of increased atmospheric CO{sub 2} concentration, climate changes, and ongoing technological advancements on bean (Phaseolus vulgaris) and maize (Zea mays) yield. This investigation assumes that the atmospheric CO{sub 2} concentration evolves according to the A2 scenario. For these analyses we have used climate data as projected by climate simulations conducted with the HadCM3 climate model for both present day and greenhouse warming conditions. The results demonstrated that warming conditions associated with increased greenhouse gases as delivered by the HadCM3 model lead to reductions in the potential productivity of maize and beans for the years 2050 and 2080 by up to 30%. This thermal response is, however, damped by the highly efficient CO{sub 2} fertilization effect which is expected to increase bean productivity as compared to present day conditions. A similar investigation for maize yield revealed a different picture. It has been found that the CO{sub 2} fertilization feedback is much weaker and cannot cancel out the thermal effect. We have found, therefore, that climate changes as simulated to occur in the future are not favorable for increasing the maize yield in southeast Brazil. By the inclusion of the third forcing evaluated, representing technological advancements, it is demonstrated that improvements in the crop system reduce the negative effect associated with warmer climate conditions for both crops. We conclude that appropriate soil and technological management as well as genetic improvements may very likely induce an increase in bean and maize yield despite the unfavorable future climate conditions.

  18. Radiative forcing estimates of sulfate aerosol in coupled climate-chemistry models with emphasis on the role of the temporal variability

    Directory of Open Access Journals (Sweden)

    C. Déandreis

    2012-06-01

    Full Text Available This paper describes the impact on the sulfate aerosol radiative effects of coupling the radiative code of a global circulation model with a chemistry-aerosol module. With this coupling, temporal variations of sulfate aerosol concentrations influence the estimate of aerosol radiative impacts. Effects of this coupling have been assessed on net fluxes, radiative forcing and temperature for the direct and first indirect effects of sulfate.

    The direct effect respond almost linearly to rapid changes in concentrations whereas the first indirect effect shows a strong non-linearity. In particular, sulfate temporal variability causes a modification of the short wave net fluxes at the top of the atmosphere of +0.24 and +0.22 W m−2 for the present and preindustrial periods, respectively. This change is small compared to the value of the net flux at the top of the atmosphere (about 240 W m−2. The effect is more important in regions with low-level clouds and intermediate sulfate aerosol concentrations (from 0.1 to 0.8 μg (SO4 m−3 in our model.

    The computation of the aerosol direct radiative forcing is quite straightforward and the temporal variability has little effect on its mean value. In contrast, quantifying the first indirect radiative forcing requires tackling technical issues first. We show that the preindustrial sulfate concentrations have to be calculated with the same meteorological trajectory used for computing the present ones. If this condition is not satisfied, it introduces an error on the estimation of the first indirect radiative forcing. Solutions are proposed to assess radiative forcing properly. In the reference method, the coupling between chemistry and climate results in a global average increase of 8% in the first indirect radiative forcing. This change reaches 50% in the most sensitive regions. However, the reference method is not suited to run long climate

  19. Combined fishing and climate forcing in the southern Benguela upwelling ecosystem: an end-to-end modelling approach reveals dampened effects.

    Directory of Open Access Journals (Sweden)

    Morgane Travers-Trolet

    Full Text Available The effects of climate and fishing on marine ecosystems have usually been studied separately, but their interactions make ecosystem dynamics difficult to understand and predict. Of particular interest to management, the potential synergism or antagonism between fishing pressure and climate forcing is analysed in this paper, using an end-to-end ecosystem model of the southern Benguela ecosystem, built from coupling hydrodynamic, biogeochemical and multispecies fish models (ROMS-N2P2Z2D2-OSMOSE. Scenarios of different intensities of upwelling-favourable wind stress combined with scenarios of fishing top-predator fish were tested. Analyses of isolated drivers show that the bottom-up effect of the climate forcing propagates up the food chain whereas the top-down effect of fishing cascades down to zooplankton in unfavourable environmental conditions but dampens before it reaches phytoplankton. When considering both climate and fishing drivers together, it appears that top-down control dominates the link between top-predator fish and forage fish, whereas interactions between the lower trophic levels are dominated by bottom-up control. The forage fish functional group appears to be a central component of this ecosystem, being the meeting point of two opposite trophic controls. The set of combined scenarios shows that fishing pressure and upwelling-favourable wind stress have mostly dampened effects on fish populations, compared to predictions from the separate effects of the stressors. Dampened effects result in biomass accumulation at the top predator fish level but a depletion of biomass at the forage fish level. This should draw our attention to the evolution of this functional group, which appears as both structurally important in the trophic functioning of the ecosystem, and very sensitive to climate and fishing pressures. In particular, diagnoses considering fishing pressure only might be more optimistic than those that consider combined effects

  20. 10 Facts on Climate Change and Health

    Science.gov (United States)

    ... sufficient quantities of carbon dioxide and other greenhouse gases to affect the global climate. The atmospheric concentration of carbon dioxide has increased by more than 30% since pre-industrial times, trapping more heat in the lower atmosphere. ...

  1. Forecasting carbon dioxide emissions.

    Science.gov (United States)

    Zhao, Xiaobing; Du, Ding

    2015-09-01

    This study extends the literature on forecasting carbon dioxide (CO2) emissions by applying the reduced-form econometrics approach of Schmalensee et al. (1998) to a more recent sample period, the post-1997 period. Using the post-1997 period is motivated by the observation that the strengthening pace of global climate policy may have been accelerated since 1997. Based on our parameter estimates, we project 25% reduction in CO2 emissions by 2050 according to an economic and population growth scenario that is more consistent with recent global trends. Our forecasts are conservative due to that we do not have sufficient data to fully take into account recent developments in the global economy. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Research Progress in Carbon Dioxide Storage and Enhanced Oil Recovery

    Science.gov (United States)

    Wang, Keliang; Wang, Gang; Lu, Chunjing

    2018-02-01

    With the rapid development of global economy, human beings have become highly dependent upon fossil fuel such as coal and petroleum. Much fossil fuel is consumed in industrial production and human life. As a result, carbon dioxide emissions have been increasing, and the greenhouse effects thereby generated are posing serious threats to environment of the earth. These years, increasing average global temperature, frequent extreme weather events and climatic changes cause material disasters to the world. After scientists’ long-term research, ample evidences have proven that emissions of greenhouse gas like carbon dioxide have brought about tremendous changes to global climate. To really reduce carbon dioxide emissions, governments of different countries and international organizations have invested much money and human resources in performing research related to carbon dioxide emissions. Manual underground carbon dioxide storage and carbon dioxide-enhanced oil recovery are schemes with great potential and prospect for reducing carbon dioxide emissions. Compared with other schemes for reducing carbon dioxide emissions, aforementioned two schemes exhibit high storage capacity and yield considerable economic benefits, so they have become research focuses for reducing carbon dioxide emissions. This paper introduces the research progress in underground carbon dioxide storage and enhanced oil recovery, pointing out the significance and necessity of carbon dioxide-driven enhanced oil recovery.

  3. Global Climatic Change.

    Science.gov (United States)

    Houghton, Richard A.; Woodwell, George M.

    1989-01-01

    Cites some of the evidence which suggests that the production of carbon dioxide and methane from human activities has begun to change the climate. Describes some measures which should be taken to stop or slow this progression. (RT)

  4. Radiolarian abundance - A monsoon proxy responding to the Earth`s orbital forcing: Inferences on the mid-Brunhes climate shift

    Digital Repository Service at National Institute of Oceanography (India)

    Gupta, S.M.

    stream_size 32348 stream_content_type text/plain stream_name Earth_Sci_India_2_1.pdf.txt stream_source_info Earth_Sci_India_2_1.pdf.txt Content-Encoding UTF-8 Content-Type text/plain; charset=UTF-8 Gupta http://www....earthscienceindia.info/Gupta.htm 1 of 8 1/28/2009 3:14 PM Earth Science India Vol.2 (I),January, 2009, pp. 1-20 http://www.earthscienceindia.info/ Radiolarian abundance - a monsoon proxy responding to the Earth’s orbital forcing: Inferences on the mid-Brunhes climate shift Shyam...

  5. Response and adaptation of grapevine cultivars to hydrological conditions forced by a changing climate in a complex landscape

    Science.gov (United States)

    De Lorenzi, Francesca; Bonfante, Antonello; Alfieri, Silvia Maria; Monaco, Eugenia; De Mascellis, Roberto; Manna, Piero; Menenti, Massimo

    2014-05-01

    Soil water availability is one of the main components of the terroir concept, influencing crop yield and fruit composition in grapes. The aim of this work is to analyze some elements of the "natural environment" of terroir (climate and soil) in combination with the intra-specific biodiversity of yield responses of grapevine to water availability. From a reference (1961-90) to a future (2021-50) climate case, the effects of climate evolution on soil water availability are assessed and, regarding soil water regime as a predictor variable, the potential spatial distribution of wine-producing cultivars is determined. In a region of Southern Italy (Valle Telesina, 20,000 ha), where a terroir classification has been produced (Bonfante et al., 2011), we applied an agro-hydrological model to determine water availability indicators. Simulations were performed in 60 soil typological units, over the entire study area, and water availability (= hydrological) indicators were determined. Two climate cases were considered: reference (1961-90) and future (2021-2050), the former from climatic statistics on observed variables, and the latter from statistical downscaling of predictions by general circulation models (AOGCM) under A1B SRES scenario. Climatic data consist of daily time series of maximum and minimum temperature, and daily rainfall on a grid with a spatial resolution of 35 km. Spatial and temporal variability of hydrological indicators was addressed. With respect to temporal variability, both inter-annual and intra-annual (i.e. at different stages of crop cycle) variability were analyzed. Some cultivar-specific relations between hydrological indicators and characteristics of must quality were established. Moreover, for several wine-producing cultivars, hydrological requirements were determined by means of yield response functions to soil water availability, through the re-analysis of experimental data derived from scientific literature. The standard errors of estimated

  6. Evaluation of different freshwater forcing scenarios for the 8.2 ka BP event in a coupled climate model

    Energy Technology Data Exchange (ETDEWEB)

    Wiersma, A.P.; Renssen, H. [Vrije Universiteit Amsterdam, Faculty of Earth and Life Sciences, Amsterdam (Netherlands); Goosse, H.; Fichefet, T. [Universite Catholique de Louvain, Institut d' Astronomie et de Geophysique George Lemaitre, Louvain-la-Neuve (Belgium)

    2006-12-15

    To improve our understanding of the mechanism causing the 8.2 ka BP event, we investigated the response of ocean circulation in the ECBilt-CLIO-VECODE (Version 3) model to various freshwater fluxes into the Labrador Sea. Starting from an early Holocene climate state we released freshwater pulses varying in volume and duration based on published estimates. In addition we tested the effect of a baseline flow (0.172 Sv) in the Labrador Sea to account for the background-melting of the Laurentide ice-sheet on the early Holocene climate and on the response of the overturning circulation. Our results imply that the amount of freshwater released is the decisive factor in the response of the ocean, while the release duration only plays a minor role, at least when considering the short release durations (1, 2 and 5 years) of the applied freshwater pulses. Furthermore, the experiments with a baseline flow produce a more realistic early Holocene climate state without Labrador Sea Water formation. Meltwater pulses introduced into this climate state produce a prolonged weakening of the overturning circulation compared to an early Holocene climate without baseline flow, and therefore less freshwater is needed to produce an event of similar duration. (orig.)

  7. Future climate

    International Nuclear Information System (INIS)

    La Croce, A.

    1991-01-01

    According to George Woodwell, founder of the Woods Hole Research Center, due the combustion of fossil fuels, deforestation and accelerated respiration, the net annual increase of carbon, in the form of carbon dioxide, to the 750 billion tonnes already present in the earth's atmosphere, is in the order of 3 to 5 billion tonnes. Around the world, scientists, investigating the probable effects of this increase on the earth's future climate, are now formulating coupled air and ocean current models which take account of water temperature and salinity dependent carbon dioxide exchange mechanisms acting between the atmosphere and deep layers of ocean waters

  8. Detection and Attribution of Anthropogenic Climate Change Impacts

    Science.gov (United States)

    Rosenzweig, Cynthia; Neofotis, Peter

    2013-01-01

    Human-influenced climate change is an observed phenomenon affecting physical and biological systems across the globe. The majority of observed impacts are related to temperature changes and are located in the northern high- and midlatitudes. However, new evidence is emerging that demonstrates that impacts are related to precipitation changes as well as temperature, and that climate change is impacting systems and sectors beyond the Northern Hemisphere. In this paper, we highlight some of this new evidence-focusing on regions and sectors that the Intergovernmental Panel on Climate Change Fourth Assessment Report (IPCC AR4) noted as under-represented-in the context of observed climate change impacts, direct and indirect drivers of change (including carbon dioxide itself), and methods of detection. We also present methods and studies attributing observed impacts to anthropogenic forcing. We argue that the expansion of methods of detection (in terms of a broader array of climate variables and data sources, inclusion of the major modes of climate variability, and incorporation of other drivers of change) is key to discerning the climate sensitivities of sectors and systems in regions where the impacts of climate change currently remain elusive. Attributing such changes to human forcing of the climate system, where possible, is important for development of effective mitigation and adaptation. Current challenges in documenting adaptation and the role of indigenous knowledge in detection and attribution are described.

  9. Social Roots of Global Environmental Change: A World-Systems Analysis of Carbon Dioxide Emissions

    Directory of Open Access Journals (Sweden)

    J. Timmons Roberts

    2015-08-01

    Full Text Available Carbon dioxide is understood to be the most important greenhouse gas believed to be altering the global climate. This article applies world-system theory to environmental damage. An analysis of 154 countries examines the contribution of both position in the world economy and internal class and political forces in determining a nation's CO, intensity. CO, intensity is defined here as the amount of carbon dioxide released per unit of economic output. An inverted U distribution of CO, intensity across the range of countries in the global stratification system is identified and discussed. Ordinary Least Squares regression suggests that the least efficient consumers of fossil fuels are some countries within the semi-periphery and upper periphery, spe-cifically those nations which are high exporters, those highly in debt, nations with higher military spending, and those with a repressive social structure.

  10. The Net Climate Impact of Coal-Fired Power Plant Emissions

    Science.gov (United States)

    Shindell, D.; Faluvegi, G.

    2010-01-01

    Coal-fired power plants influence climate via both the emission of long-lived carbon dioxide (CO2) and short-lived ozone and aerosol precursors. Using a climate model, we perform the first study of the spatial and temporal pattern of radiative forcing specifically for coal plant emissions. Without substantial pollution controls, we find that near-term net global mean climate forcing is negative due to the well-known aerosol masking of the effects of CO2. Imposition of pollution controls on sulfur dioxide and nitrogen oxides leads to a rapid realization of the full positive forcing from CO2, however. Long-term global mean forcing from stable (constant) emissions is positive regardless of pollution controls. Emissions from coal-fired power plants until 1970, including roughly 1/3 of total anthropogenic CO2 emissions, likely contributed little net global mean climate forcing during that period though they may have induce weak Northern Hemisphere mid-latitude (NHml) cooling. After that time many areas imposed pollution controls or switched to low sulfur coal. Hence forcing due to emissions from 1970 to 2000 and CO2 emitted previously was strongly positive and contributed to rapid global and especially NHml warming. Most recently, new construction in China and India has increased rapidly with minimal application of pollution controls. Continuation of this trend would add negative near-term global mean climate forcing but severely degrade air quality. Conversely, following the Western and Japanese pattern of imposing air quality pollution controls at a later time could accelerate future warming rates, especially at NHmls. More broadly, our results indicate that due to spatial and temporal inhomogeneities in forcing, climate impacts of multi-pollutant emissions can vary strongly from region to region and can include substantial effects on maximum rate-of-change, neither of which are captured by commonly used global metrics. The method we introduce here to estimate

  11. The radiative heating response to climate change

    Science.gov (United States)

    Maycock, Amanda

    2016-04-01

    The structure and magnitude of radiative heating rates in the atmosphere can change markedly in response to climate forcings; diagnosing the causes of these changes can aid in understanding parts of the large-scale circulation response to climate change. This study separates the relative drivers of projected changes in longwave and shortwave radiative heating rates over the 21st century into contributions from radiatively active gases, such as carbon dioxide, ozone and water vapour, and from changes in atmospheric and surface temperatures. Results are shown using novel radiative diagnostics applied to timeslice experiments from the UM-UKCA chemistry-climate model; these online estimates are compared to offline radiative transfer calculations. Line-by-line calculations showing spectrally-resolved changes in heating rates due to different gases will also be presented.

  12. Lake Baikal climatic record between 310 and 50 ky BP: Interplay between diatoms, watershed weathering and orbital forcing

    Czech Academy of Sciences Publication Activity Database

    Grygar, Tomáš; Bláhová, Anna; Hradil, David; Bezdička, Petr; Kadlec, Jaroslav; Schnabl, Petr; Swann, G.; Oberhänsli, H.

    2007-01-01

    Roč. 250, 1-4 (2007), s. 50-67 ISSN 0031-0182 R&D Projects: GA AV ČR IAA3032401 Institutional research plan: CEZ:AV0Z40320502; CEZ:AV0Z3013912 Keywords : lake sediments * climate change * spectroscopy Subject RIV: CA - Inorganic Chemistry Impact factor: 2.162, year: 2007

  13. Implications of the methodological choices for hydrologic portrayals of climate change over the contiguous United States: Statistically downscaled forcing data and hydrologic models

    Science.gov (United States)

    Mizukami, Naoki; Clark, Martyn P.; Gutmann, Ethan D.; Mendoza, Pablo A.; Newman, Andrew J.; Nijssen, Bart; Livneh, Ben; Hay, Lauren E.; Arnold, Jeffrey R.; Brekke, Levi D.

    2016-01-01

    Continental-domain assessments of climate change impacts on water resources typically rely on statistically downscaled climate model outputs to force hydrologic models at a finer spatial resolution. This study examines the effects of four statistical downscaling methods [bias-corrected constructed analog (BCCA), bias-corrected spatial disaggregation applied at daily (BCSDd) and monthly scales (BCSDm), and asynchronous regression (AR)] on retrospective hydrologic simulations using three hydrologic models with their default parameters (the Community Land Model, version 4.0; the Variable Infiltration Capacity model, version 4.1.2; and the Precipitation–Runoff Modeling System, version 3.0.4) over the contiguous United States (CONUS). Biases of hydrologic simulations forced by statistically downscaled climate data relative to the simulation with observation-based gridded data are presented. Each statistical downscaling method produces different meteorological portrayals including precipitation amount, wet-day frequency, and the energy input (i.e., shortwave radiation), and their interplay affects estimations of precipitation partitioning between evapotranspiration and runoff, extreme runoff, and hydrologic states (i.e., snow and soil moisture). The analyses show that BCCA underestimates annual precipitation by as much as −250 mm, leading to unreasonable hydrologic portrayals over the CONUS for all models. Although the other three statistical downscaling methods produce a comparable precipitation bias ranging from −10 to 8 mm across the CONUS, BCSDd severely overestimates the wet-day fraction by up to 0.25, leading to different precipitation partitioning compared to the simulations with other downscaled data. Overall, the choice of downscaling method contributes to less spread in runoff estimates (by a factor of 1.5–3) than the choice of hydrologic model with use of the default parameters if BCCA is excluded.

  14. Grassland gross carbon dioxide uptake based on an improved model tree ensemble approach considering human interventions: global estimation and covariation with climate.

    Science.gov (United States)

    Liang, Wei; Lü, Yihe; Zhang, Weibin; Li, Shuai; Jin, Zhao; Ciais, Philippe; Fu, Bojie; Wang, Shuai; Yan, Jianwu; Li, Junyi; Su, Huimin

    2017-07-01

    Grassland ecosystems act as a crucial role in the global carbon cycle and provide vital ecosystem services for many species. However, these low-productivity and water-limited ecosystems are sensitive and vulnerable to climate perturbations and human intervention, the latter of which is often not considered due to lack of spatial information regarding the grassland management. Here by the application of a model tree ensemble (MTE-GRASS) trained on local eddy covariance data and using as predictors gridded climate and management intensity field (grazing and cutting), we first provide an estimate of global grassland gross primary production (GPP). GPP from our study compares well (modeling efficiency NSE = 0.85 spatial; NSE between 0.69 and 0.94 interannual) with that from flux measurement. Global grassland GPP was on average 11 ± 0.31 Pg C yr -1 and exhibited significantly increasing trend at both annual and seasonal scales, with an annual increase of 0.023 Pg C (0.2%) from 1982 to 2011. Meanwhile, we found that at both annual and seasonal scale, the trend (except for northern summer) and interannual variability of the GPP are primarily driven by arid/semiarid ecosystems, the latter of which is due to the larger variation in precipitation. Grasslands in arid/semiarid regions have a stronger (33 g C m -2  yr -1 /100 mm) and faster (0- to 1-month time lag) response to precipitation than those in other regions. Although globally spatial gradients (71%) and interannual changes (51%) in GPP were mainly driven by precipitation, where most regions with arid/semiarid climate zone, temperature and radiation together shared half of GPP variability, which is mainly distributed in the high-latitude or cold regions. Our findings and the results of other studies suggest the overwhelming importance of arid/semiarid regions as a control on grassland ecosystems carbon cycle. Similarly, under the projected future climate change, grassland ecosystems in these regions will

  15. Carbon Dioxide Effects Research and Assessment Program. Workshop on environmental and societal consequences of a possible CO/sub 2/-induced climate change

    Energy Technology Data Exchange (ETDEWEB)

    None

    1980-10-01

    The Workshop was part of a process of elucidating areas of uncertainty where research is needed before meaningful forecasts and sound decisions can be made about the CO/sub 2/ issue. The conferees were divided into five panels dealing with the ocean and the cryosphere: the less managed biosphere; the managed biosphere (chiefly agricultural, forest, and grazing lands); the ways society and its institutions might respond to climate changes; and issues involving the economic and geopolitical consequences of CO/sub 2/ build-up. Also, 28 papers or discussion drafts dealing with a wide variety of topics were contributed to the conference.

  16. The greenhouse effect and climate warming up

    International Nuclear Information System (INIS)

    Leygonie, R.

    1992-01-01

    The present article is a follow-up to a previous article, under the same title, which describes the scientific bases of the greenhouse effect and the prospect, based on climatic global models, of a potential climate warming up. The conclusions of the Intergovernmental Panel on Climate Change (IPCC, August 1990) were summarized, predicting a mean global temperature increase between 2.4 and 5.1 deg C in 2070, among other changes. The recent IPCC work confirms 1990 conclusions but states that the decline of ozone in the lower stratosphere could neutralize the radiative forcing of chlorofluorocarbons. At least ten more years of investigation are needed to ascertain an increase of the greenhouse effect. Information is given on recent events which may be connected with the global climate problem, in particular the spectacular eruption of the Pinatubo volcano, in mid 1991, cause of a probable cooling of the atmosphere and a potential decrease of radiative forcing due to anthropogenic dioxide emissions. The most important recent events in the political field is a directive proposal by the European Commission aimed at a taxation of both energy in general and of carbon dioxide emissions by fossil fuels. Another event is the United Nations Convention on climate change, signed by 155 countries at the Rio de Janeiro Conference on Environment and Development, which pledges signatories to decrease their greenhouse gas - emissions but no figures are given on percentages and calendar of reduction. At last, a short chapter is devoted to the French ECLAT programme on climate change which consists both in participating in world programmes and in performing original investigations by French Scientists

  17. Nr 470 - Report on the behalf of the Commission of foreign affairs, defence and armed forces on the bill project authorizing the approval of amendments of appendices II and III to the OSPAR convention for the protection of the marine environment of the North-East Atlantic related to the storage of carbon dioxide fluxes in geological structures

    International Nuclear Information System (INIS)

    Aichi, Leila

    2013-01-01

    This report first discusses the necessity to protect the marine environment of the north-east Atlantic Ocean. It briefly recalls the content and objectives of the OSPAR convention, and outlines the need of a permanent update of this convention to take measures of struggle against climate change into account. Notably, two amendments introduced the interdiction of storage of carbon dioxide fluxes. It highlights the need to protect the Arctic Ocean area. In a second part, the report discusses the emergence of a new technique for the storage of CO 2 (the injection in geological structures), and shows that this technique complies with the objective of struggle against climate change. However, the authors also mention the worrying potential risk for the ecosystem, and the fact that this technique should complement but not replace other measures against climate change

  18. More bad news about carbon dioxide emissions

    International Nuclear Information System (INIS)

    Stonehouse, D.

    2000-01-01

    The affect that increased carbon dioxide concentrations has on plants and animals was discussed. Most research focuses on the impacts that carbon dioxide concentrations has on climatic change. Recent studies, however, have shown that elevated levels of carbon dioxide in the atmosphere caused by burning fossils fuels changes the chemical structure of plants and could lead to significant disruptions in ecological food chains. High carbon dioxide levels cause plants to speed up photosynthesis, take in the gas, and use the carbon to produce more fibre and starch while giving off oxygen as a byproduct. As plants produce more carbon, their levels of nitrogen diminish making them less nutritious for the insects and animals that feed on them. This has serious implications for farmers, as pests would have to eat more of their crops to survive. In addition, farmers would have to supplement livestock with nutrients

  19. A record of astronomically forced climate change in a late Ordovician (Sandbian) deep marine sequence, Ordos Basin, North China

    Science.gov (United States)

    Fang, Qiang; Wu, Huaichun; Hinnov, Linda A.; Wang, Xunlian; Yang, Tianshui; Li, Haiyan; Zhang, Shihong

    2016-07-01

    The late Ordovician Pingliang Formation on the southwestern margin of the Ordos Basin, North China, consists of rhythmic alternations of shale, limestone, and siliceous beds. To explore the possible astronomical forcing preserved in this lithological record, continuous lithological rank and magnetic susceptibility (MS) stratigraphic series were obtained from a 34 m thick section of the Pingliang Formation at Guanzhuang. Power spectral analysis of the MS and rank series reveal 85.5 cm to 124 cm, 23 cm to 38 cm, and 15 cm to 27 cm thick sedimentary cycles that in ratio match that of late Ordovician short eccentricity, obliquity and precession astronomical cycles. The power spectrum of the MS time series, calibrated to interpreted short orbital eccentricity cycles, aligns with spectral peaks to astronomical parameters, including 95 kyr short orbital eccentricity, 35.3 kyr and 30.6 kyr obliquity, and 19.6 kyr and 16.3 kyr precession cycles. The 15 cm to 27 cm thick limestone-shale couplets mainly represent precession cycles, and siliceous bed deposition may be related to both precession and obliquity forcing. We propose that precession-forced sea-level fluctuations mainly controlled production of lime mud in a shallow marine environment, and transport to the basin. Precession and obliquity controlled biogenic silica productivity, and temperature-dependent preservation of silica may have been influenced by obliquity forcing.

  20. Extinction risks forced by climatic change and intraspecific variation in the thermal physiology of a tropical lizard.

    Science.gov (United States)

    Pontes-da-Silva, Emerson; Magnusson, William E; Sinervo, Barry; Caetano, Gabriel H; Miles, Donald B; Colli, Guarino R; Diele-Viegas, Luisa M; Fenker, Jessica; Santos, Juan C; Werneck, Fernanda P

    2018-04-01

    Temperature increases can impact biodiversity and predicting their effects is one of the main challenges facing global climate-change research. Ectotherms are sensitive to temperature change and, although predictions indicate that tropical species are highly vulnerable to global warming, they remain one of the least studied groups with respect to the extent of physiological variation and local extinction risks. We model the extinction risks for a tropical heliothermic teiid lizard (Kentropyx calcarata) integrating previously obtained information on intraspecific phylogeographic structure, eco-physiological traits and contemporary species distributions in the Amazon rainforest and its ecotone to the Cerrado savannah. We also investigated how thermal-biology traits vary throughout the species' geographic range and the consequences of such variation for lineage vulnerability. We show substantial variation in thermal tolerance of individuals among thermally distinct sites. Thermal critical limits were highly correlated with operative environmental temperatures. Our physiological/climatic model predicted relative extinction risks for local populations within clades of K. calcarata for 2050 ranging between 26.1% and 70.8%, while for 2070, extinction risks ranged from 52.8% to 92.8%. Our results support the hypothesis that tropical-lizard taxa are at high risk of local extinction caused by increasing temperatures. However, the thermo-physiological differences found across the species' distribution suggest that local adaptation may allow persistence of this tropical ectotherm in global warming scenarios. These results will serve as basis to further research to investigate the strength of local adaptation to climate change. Persistence of Kentropyx calcarata also depends on forest preservation, but the Amazon rainforest is currently under high deforestation rates. We argue that higher conservation priority is necessary so the Amazon rainforest can fulfill its capacity to

  1. Long-term hydrodynamic response induced by past climatic and geo-morphologic forcing: The case of the Paris basin, France

    International Nuclear Information System (INIS)

    Jost, A.; Violette, S.; Goncalves, J.; Ledoux, E.; Guyomard, Y.; Guillocheau, F.; Kageyama, M.; Ramstein, G.; Suc, J.P.

    2007-01-01

    In the framework of safe underground storage of radioactive waste in low-permeability layers, it is essential to evaluate the mobility of deep groundwaters over timescales of several million years. On these timescales, the environmental evolution of a repository should depend upon a range of natural processes that are primarily driven by climate and geo-morphologic variations. In this paper, the response of the Paris basin groundwater system to variations in its hydrodynamic boundary conditions induced by past climate and geodynamic changes over the last five million years is investigated. A three-dimensional transient modelling of the Paris basin aquifer/aquitard system was developed using the code NEWSAM (Ecole des Mines de Paris, ENSMP). The geometry and hydrodynamic parameters of the model originate from a basin model, NEWBAS (ENSMP), built to simulate the geological history of the basin. Geo-morphologic evolution is deduced from digital elevation model analysis, which allows to estimate river-valley incision and alpine uplift. Climate forcing results from paleo-climate modelling experiments using the LMDz atmospheric general circulation model (Institut Pierre Simon Laplace) with a refined spatial resolution, for the present, the Last Glacial Maximum (21 ka) and the Middle Pliocene Warmth (similar to 3 Ma). The water balance is computed by the distributed hydrological model MODSUR (ENSMP). Results about the simulated evolution of piezometric heads in the system in response to the altered boundary conditions are presented, in particular in the vicinity of ANDRA's Bure potential repository site within the Callovo-Oxfordian argillaceous layer. For the present, the comparison of head patterns between steady state and time dependent simulation shows little differences for aquifer layers close to the surface but suggests a transient state of the current system in the main aquitards of the basin and in the deep aquifers, characterized by abnormally low fluid

  2. Comparison of Water and Nutrient Cycles in the North China Plain and U.S. High Plains related to Climate Forcing

    Science.gov (United States)

    Scanlon, B. R.; Pei, H.; Shen, Y.

    2014-12-01

    The North China Plain (NCP) and U.S. High Plains play critical roles in food production, which relies heavily on groundwater resources for irrigation and nutrients. Here we evaluate food production in terms of resource availability (water and nutrients) and impacts on resources (groundwater quantity and quality) within the context of climate forcing. Double cropping of corn and wheat in the NCP under intensive irrigation (80 - 90% of cropland) and massive N fertilization (384 kg/ha) resulted in total corn plus wheat yields of 13.4 kg/ha (2002 - 2011). In contrast, single cropping of corn on the USHP under less intensive irrigation (40% of cropland) and N fertilization (90 kg/ha) resulted in only 15% lower yield in the USHP (11.7 kg/ha) than in the NCP. However, irrigation essentially decouples crop production from climate extremes. Average corn and wheat yield in the NCP over the past three decades is not correlated with precipitation. Irrigated corn yield in the north and central USHP was actually higher during the recent 2012 drought by up to ~ 30% relative to the 30 year long-term mean yield whereas rainfed corn yield decreased by ~50% during the drought. The main impact of climate extremes on the aquifers is indirect through increased irrigation pumpage for crop production rather than direct through changes in recharge. Effects of crop production on groundwater quality should be much greater in the NCP because of ~4 times higher fertilizer application relative to that in the USHP. Field research experiments in the NCP indicate that much of this fertilizer application (> 200 kg N/ha) does not impact yield and could potentially leach into underlying aquifers. Projected groundwater depletion in these aquifers should result in a shift from intensive irrigation to more rainfed crop production, increasing vulnerability of crop production to climate extremes.

  3. Post-glacial climate forcing of surface processes in the Ganges-Brahmaputra river basin and implications for carbon sequestration

    Science.gov (United States)

    Hein, Christopher J.; Galy, Valier; Galy, Albert; France-Lanord, Christian; Kudrass, Hermann; Schwenk, Tilmann

    2017-11-01

    Climate has been proposed to control both the rate of terrestrial silicate weathering and the export rate of associated sediments and terrestrial organic carbon to river-dominated margins - and thus the rate of sequestration of atmospheric CO2 in the coastal ocean - over glacial-interglacial timescales. Focused on the Ganges-Brahmaputra rivers, this study presents records of post-glacial changes in basin-scale Indian summer monsoon intensity and vegetation composition based on stable hydrogen (δD) and carbon (δ13C) isotopic compositions of terrestrial plant wax compounds preserved in the channel-levee system of the Bengal Fan. It then explores the role of these changes in controlling the provenance and degree of chemical weathering of sediments exported by these rivers, and the potential climate feedbacks through organic-carbon burial in the Bengal Fan. An observed 40‰ shift in δD and a 3-4‰ shift in both bulk organic-carbon and plant-wax δ13C values between the late glacial and mid-Holocene, followed by a return to more intermediate values during the late Holocene, correlates well with regional post-glacial paleoclimate records. Sediment provenance proxies (Sr, Nd isotopic compositions) reveal that these changes likely coincided with a subtle focusing of erosion on the southern flank of the Himalayan range during periods of greater monsoon strength and enhanced sediment discharge. However, grain-size-normalized organic-carbon concentrations in the Bengal Fan remained constant through time, despite order-of-magnitude level changes in catchment-scale monsoon precipitation and enhanced chemical weathering (recorded as a gradual increase in K/Si* and detrital carbonate content, and decrease in H2O+/Si*, proxies) throughout the study period. These findings demonstrate a partial decoupling of climate change and silicate weathering during the Holocene and that marine organic-carbon sequestration rates primary reflect rates of physical erosion and sediment export

  4. Climate change and our responsibilities as chemists

    Directory of Open Access Journals (Sweden)

    Bassam Z. Shakhashiri

    2014-01-01

    Full Text Available For almost all of 4.5 billion years, natural forces have shaped Earth’s environment. But, during the past century, as a result of the Industrial Revolution, which has had enormous benefits for humans, the effects of human activities have become the main driver for climate change. The increase of atmospheric carbon dioxide caused by burning fossil fuels for energy to power the revolution causes an energy imbalance between incoming solar radiation and outgoing planetary emission. The imbalance is warming the planet and causing the atmosphere and oceans to warm, ice to melt, sea level to rise, and weather extremes to increase. In addition, dissolution of part of the carbon dioxide in the oceans is causing them to acidify, with possible negative effects on marine biota. As citizens of an interconnected global society and scientists who have the background to understand climate change, we have a responsibility first to understand the science. One resource that is available to help is the American Chemical Society Climate Science Toolkit, www.acs.org/climatescience. With this understanding our further responsibility as citizen scientists is to engage others in deliberative discussions on the science, to take actions ourselves to adapt to and mitigate human-caused climate change, and urge others to follow our example.

  5. Carbon dioxide capture and air quality

    NARCIS (Netherlands)

    Horssen, A. van; Ramirez, C.A.; Harmelen, T. van; Koornneef, J.

    2011-01-01

    Carbon dioxide (CO2) is one of the most important greenhouse gases (GHG). The most dominant source of anthropogenic CO2 contributing to the rise in atmospheric concentration since the industrial revolution is the combustion of fossil fuels. These emissions are expected to result in global climate

  6. Climate change

    International Nuclear Information System (INIS)

    Anon.

    1990-01-01

    In this paper, the authors discuss in brief the magnitude and rate of past changes in climate and examine the various factors influencing climate in order to place the potential warming due to increasing greenhouse gas concentrations in context. Feedback mechanisms that can amplify or lessen imposed climate changes are discussed next. The overall sensitivity of climate to changes in forcing is then considered, followed by a discussion of the time-dependent response of the Earth system. The focus is on global temperature as an indicator for the magnitude of climatic change

  7. Long-term ice sheet-climate interactions under anthropogenic greenhouse forcing simulated with a complex Earth System Model

    Energy Technology Data Exchange (ETDEWEB)

    Vizcaino, Miren [Max-Planck-Institut fuer Meteorologie, Hamburg (Germany); University of California, Department of Geography, Berkeley, CA (United States); Mikolajewicz, Uwe; Maier-Reimer, Ernst [Max-Planck-Institut fuer Meteorologie, Hamburg (Germany); Groeger, Matthias [Max-Planck-Institut fuer Meteorologie, Hamburg (Germany); IFM-GEOMAR, Kiel (Germany); Schurgers, Guy [Max-Planck-Institut fuer Meteorologie, Hamburg (Germany); Lund University, Department of Physical Geography and Ecosystems Analysis, Lund (Sweden); Winguth, Arne M.E. [Center for Climatic Research, Department of Atmospheric and Oceanic Sciences, Madison (United States)

    2008-11-15

    Several multi-century and multi-millennia simulations have been performed with a complex Earth System Model (ESM) for different anthropogenic climate change scenarios in order to study the long-term evolution of sea level and the impact of ice sheet changes on the climate system. The core of the ESM is a coupled coarse-resolution Atmosphere-Ocean General Circulation Model (AOGCM). Ocean biogeochemistry, land vegetation and ice sheets are included as components of the ESM. The Greenland Ice Sheet (GrIS) decays in all simulations, while the Antarctic ice sheet contributes negatively to sea level rise, due to enhanced storage of water caused by larger snowfall rates. Freshwater flux increases from Greenland are one order of magnitude smaller than total freshwater flux increases into the North Atlantic basin (the sum of the contribution from changes in precipitation, evaporation, run-off and Greenland meltwater) and do not play an important role in changes in the strength of the North Atlantic Meridional Overturning Circulation (NAMOC). The regional climate change associated with weakening/collapse of the NAMOC drastically reduces the decay rate of the GrIS. The dynamical changes due to GrIS topography modification driven by mass balance changes act first as a negative feedback for the decay of the ice sheet, but accelerate the decay at a later stage. The increase of surface temperature due to reduced topographic heights causes a strong acceleration of the decay of the ice sheet in the long term. Other feedbacks between ice sheet and atmosphere are not important for the mass balance of the GrIS until it is reduced to 3/4 of the original size. From then, the reduction in the albedo of Greenland strongly accelerates the decay of the ice sheet. (orig.)

  8. Response of a tundra ecosystem to elevated atmospheric carbon dioxide and CO{sub 2}-induced climate change. Annual technical report

    Energy Technology Data Exchange (ETDEWEB)

    Oechel, W.C.

    1992-04-01

    Northern ecosystems contain up to 455 Gt of C in the soil active layer and upper permafrost. The soil carbon in these layers is equivalent to approximately 60% of the carbon currently in the atmosphere as CO{sub 2}. Much of this carbon is stored in the soil as dead organic matter. Its fate is subject to the net effects of global change on the plant and soil systems of northern ecosystems. The arctic alone contains about 60 Gt C, 90% of which is present in the soil active layer and upper permafrost. The arctic is assumed to have been a sink for CO{sub 2} during the historic and recent geologic past. The arctic has the potential to be a very large, long-term source or sink of CO{sub 2} with respect to the atmosphere. In situ experimental manipulations of atmospheric CO{sub 2}, indicated that there is little effect of elevated atmospheric CO{sub 2} on leaf level photosynthesis or whole-ecosystem CO{sub 2} flux over the course of weeks to years, respectively. However, there may be longer- term ecosystem responses to elevated CO{sub 2} that could ultimately affect ecosystem CO{sub 2} balance. In addition to atmospheric CO{sub 2}, climate may affect net ecosystem carbon balance. Recent results indicate that the arctic has become a source of CO{sub 2} to the atmosphere. This change coincides with recent climatic variation in the arctic, and suggests a positive feedback of arctic ecosystems on atmospheric CO{sub 2} and global change. The research proposed in this application has four principal aspects: (A) Long-term response of arctic plants and ecosystems to elevated atmospheric CO{sub 2}; (B) Circumpolar patterns of net ecosystem CO{sub 2} flux; (C) In situ controls by temperature and moisture on net ecosystem CO{sub 2} flux; (D) Scaling of CO{sub 2} flux from plot, to landscape, to regional scales (In conjunction with research proposed for NSF support).

  9. Reconstructing Middle Eocene Climate and Atmospheric Carbon Dioxide Concentration: Application of a mechanistic theoretical approach to fossil plants from the Messel Pit (Germany)

    Science.gov (United States)

    Grein, M.; Roth-Nebelsick, A.; Wilde, V.; Konrad, W.; Utescher, T.

    2009-12-01

    It is assumed that changes in atmospheric CO2 concentrations (from now on expressed as Ca) strongly influenced the development of global temperatures during parts of the Cenozoic. Thus, detailed knowledge of ancient Ca and its variations is of utmost importance for exploring the coupling of atmospheric CO2 and global climate change. Numerous techniques (such as carbon and boron isotopes) were applied in order to obtain Ca, with varying and sometimes even conflicting results. Stomatal density (number of stomata per leaf area) represents another promising proxy for the calculation of ancient Ca since many plants reduce the number of stomata (pores on the leaf surface used for gas exchange) under increasing Ca. As a reason it is assumed that plants try to adjust stomatal conductance in order to optimize their gas exchange (which means maximal assimilation at minimal transpiration). The common technique for calculating Ca from fossil stomatal frequency is to create empirical transfer functions of living plants derived from herbar material or greenhouse experiments. In the presented project, Ca of the Middle Eocene is calculated by applying a different approach which utilizes a mechanistic-theoretical calibration. It couples the processes of a) C3-photosynthesis, b) diffusion and c) transpiration with palaeoclimatic and leaf-anatomical data. The model also includes an optimisation principle supported by ecophysiological data. According to this optimisation principle, plants adjust their stomatal conductance in such a way that photosynthesis rates are constrained by optimal water use (transpiration). This model was applied in the present study to fossil plants from the Messel Pit near Darmstadt (Germany). In order to reconstruct Ca by using fossil plant taxa from Messel, numerous parameters which represent model input have to be estimated from measurements of living representatives. Furthermore, since climate parameters are also required by the model, quantitative

  10. Climate Forcing of Ripple Migration and Crest Alignment in the Last 400 kyr in Meridiani Planum, Mars

    Science.gov (United States)

    Fenton, Lori K.; Carson, Helen C.; Michaels, Timothy I.

    2018-04-01

    The plains ripples of Meridiani Planum are the first paleo-aeolian bedforms on Mars to have had their last migration episode constrained in time (to 50-200 ka). Here we test how variations in orbital configuration, air pressure, and atmospheric dust loading over the past 400 kyr affect bedform mobility and crest alignment. Using the National Aeronautics and Space Administration Ames Mars Global Climate Model, we ran a series of sensitivity tests under a number of different conditions, seeking changes in wind patterns relative to those modeled for present-day conditions. Results indicate that enhanced sand drift potential in Meridiani Planum correlates with (1) high axial obliquity, (2) a longitude of perihelion (Lp) near southern summer solstice, and (3) a greater air pressure. The last pulse of westward plains ripple migration likely occurred during the most recent obliquity (relative) maximum, from 111 to 86 ka. At Lp coinciding with southern summer solstice, the Mars Global Climate Model produced a westward resultant drift direction, consistent with the observed north-south plains ripple crest alignment. However, smaller superposed ripples, aligned NNE-SSW, are consistent with a strengthened northern summer Hadley return flow, occurring when Lp coincided with northern summer solstice. The superposed NNE-SSW ripples likely formed as the axial obliquity decreased during the last relative maximum and Lp swung toward northern summer, from 86 to 72 ka. The timeline of bedform activity supports the proposed sequence of CO2 sequestration in the south polar residual cap over the past 400 kyr.

  11. Climatic change

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1977-02-15

    In spite of man's remarkable advances in technology, ultimately he is still dependent on the Earth's climatic system for food and fresh water. The recent occurrences in certain regions of the world of climatic extremes such as excessive rain or droughts and unseasonably high or low temperatures have led to speculation that a major climatic change is occurring on a global scale. Some point to the recent drop in temperatures in the northern hemisphere as an indication that the Earth is entering a new ice age. Others see a global warming trend that may be due to a build-up of carbon dioxide in the atmosphere. An authoritative report on the subject has been prepared by a World Meteorological Organization Panel of Experts on Climatic Change. Excerpts from the report are given. (author)

  12. Climatic change

    International Nuclear Information System (INIS)

    1977-01-01

    In spite of man's remarkable advances in technology, ultimately he is still dependent on the Earth's climatic system for food and fresh water. The recent occurrences in certain regions of the world of climatic extremes such as excessive rain or droughts and unseasonably high or low temperatures have led to speculation that a major climatic change is occurring on a global scale. Some point to the recent drop in temperatures in the northern hemisphere as an indication that the Earth is entering a new ice age. Others see a global warming trend that may be due to a build-up of carbon dioxide in the atmosphere. An authoritative report on the subject has been prepared by a World Meteorological Organization Panel of Experts on Climatic Change. Excerpts from the report are given. (author)

  13. Cogeneration and carbon dioxide emissions of a city - Legal aspects and distributed heat and power production; L'impact des couplages chaleur-force sur les emissions de CO{sub 2} d'une ville. Cadre institutionnel et productions decentralisees

    Energy Technology Data Exchange (ETDEWEB)

    Cherix, G. [Centre de Recherches Energetiques et Municipales (CREM), Martigny (Switzerland)

    2010-07-01

    This article reviews the impacts of combined generation of heat and power in urban areas on energy consumption and carbon dioxide emissions and emphasises the necessity of accelerating the implementation of such systems, given the present climate change and its negative consequences. The author describes in particular the relevance of distributed cogeneration units with natural gas or biogas engines. These units efficiently reduce the primary energy consumption. Local, regional and national authorities should create the framework conditions favorable to the rapid development of this technology.

  14. Response of a tundra ecosystem to elevated atmospheric carbon dioxide and CO{sub 2}-induced climate change. Annual technical report

    Energy Technology Data Exchange (ETDEWEB)

    Oechel, W.C.

    1993-02-01

    Northern ecosystems contain up to 455 Gt of C in the soil active layer and upper permafrost, which is equivalent to approximately 60% of the carbon currently in the atmosphere as CO{sub 2}. Much of this carbon is stored in the soil as dead organic matter. Its fate is subject to the net effects of global change on the plant and soil systems of northern ecosystems. The arctic alone contains about 60 Gt C, 90% of which is present in the soil active layer and upper permafrost, and is assumed to have been a sink for CO{sub 2} during the historic and recent geologic past. Depending on the nature, rate, and magnitude of global environmental change, the arctic may have a positive or negative feedback on global change. Results from the DOE- funded research efforts of 1990 and 1991 indicate that the arctic has become a source of CO{sub 2} to the atmosphere. Measurements made in the Barrow, Alaska region during 1992 support these results. This change coincides with recent climatic variation in the arctic, and suggests a positive feedback of arctic ecosystems on atmospheric CO{sub 2} and global change. There are obvious potential errors in scaling plot level measurements to landscape, mesoscale, and global spatial scales. In light of the results from the recent DOE-funded research, and the remaining uncertainties regarding the change in arctic ecosystem function due to high latitude warming, a revised set of research goals is proposed for the 1993--94 year. The research proposed in this application has four principal aspects: (A) Long- term response of arctic plants and ecosystems to elevated atmospheric CO{sub 2}. (B) Circumpolar patterns of net ecosystem CO{sub 2} flux. (C) In situ controls by temperature and moisture on net ecosystem CO{sub 2} flux. (D) Scaling of CO{sub 2} flux from plot, to landscape, to regional scales.

  15. Arctic climate response to forcing from light-absorbing particles in snow and sea ice in CESM

    Directory of Open Access Journals (Sweden)

    N. Goldenson

    2012-09-01

    Full Text Available The presence of light-absorbing aerosol particles deposited on arctic snow and sea ice influences the surface albedo, causing greater shortwave absorption, warming, and loss of snow and sea ice, lowering the albedo further. The Community Earth System Model version 1 (CESM1 now includes the radiative effects of light-absorbing particles in snow on land and sea ice and in sea ice itself. We investigate the model response to the deposition of black carbon and dust to both snow and sea ice. For these purposes we employ a slab ocean version of CESM1, using the Community Atmosphere Model version 4 (CAM4, run to equilibrium for year 2000 levels of CO2 and fixed aerosol deposition. We construct experiments with and without aerosol deposition, with dust or black carbon deposition alone, and with varying quantities of black carbon and dust to approximate year 1850 and 2000 deposition fluxes. The year 2000 deposition fluxes of both dust and black carbon cause 1–2 °C of surface warming over large areas of the Arctic Ocean and sub-Arctic seas in autumn and winter and in patches of Northern land in every season. Atmospheric circulation changes are a key component of the surface-warming pattern. Arctic sea ice thins by on average about 30 cm. Simulations with year 1850 aerosol deposition are not substantially different from those with year 2000 deposition, given constant levels of CO2. The climatic impact of particulate impurities deposited over land exceeds that of particles deposited over sea ice. Even the surface warming over the sea ice and sea ice thinning depends more upon light-absorbing particles deposited over land. For CO2 doubled relative to year 2000 levels, the climate impact of particulate impurities in snow and sea ice is substantially lower than for the year 2000 equilibrium simulation.

  16. Carbon dioxide capture and storage

    International Nuclear Information System (INIS)

    Durand, B.

    2011-01-01

    The author first highlights the reasons why storing carbon dioxide in geological formations could be a solution in the struggle against global warming and climate change. Thus, he comments various evolutions and prospective data about carbon emissions or fossil energy consumption as well as various studies performed by international bodies and agencies which show the interest of carbon dioxide storage. He comments the evolution of CO 2 contributions of different industrial sectors and activities, notably in France. He presents the different storage modes and methods which concern different geological formations (saline aquifers, abandoned oil or gas fields, not exploitable coal seams) and different processes (sorption, carbonation). He discusses the risks associated with these storages, the storable quantities, evokes some existing installations in different countries. He comments different ways to capture carbon dioxide (in post-combustion, through oxy-combustion, by pre-combustion) and briefly evokes some existing installations. He evokes the issue of transport, and discusses efficiency and cost aspects, and finally has few words on legal aspects and social acceptability

  17. Sensitivity of monthly streamflow forecasts to the quality of rainfall forcing: When do dynamical climate forecasts outperform the Ensemble Streamflow Prediction (ESP) method?

    Science.gov (United States)

    Tanguy, M.; Prudhomme, C.; Harrigan, S.; Smith, K. A.; Parry, S.

    2017-12-01

    Forecasting hydrological extremes is challenging, especially at lead times over 1 month for catchments with limited hydrological memory and variable climates. One simple way to derive monthly or seasonal hydrological forecasts is to use historical climate data to drive hydrological models using the Ensemble Streamflow Prediction (ESP) method. This gives a range of possible future streamflow given known initial hydrologic conditions alone. The degree of skill of ESP depends highly on the forecast initialisation month and catchment type. Using dynamic rainfall forecasts as driving data instead of historical data could potentially improve streamflow predictions. A lot of effort is being invested within the meteorological community to improve these forecasts. However, while recent progress shows promise (e.g. NAO in winter), the skill of these forecasts at monthly to seasonal timescales is generally still limited, and the extent to which they might lead to improved hydrological forecasts is an area of active research. Additionally, these meteorological forecasts are currently being produced at 1 month or seasonal time-steps in the UK, whereas hydrological models require forcings at daily or sub-daily time-steps. Keeping in mind these limitations of available rainfall forecasts, the objectives of this study are to find out (i) how accurate monthly dynamical rainfall forecasts need to be to outperform ESP, and (ii) how the method used to disaggregate monthly rainfall forecasts into daily rainfall time series affects results. For the first objective, synthetic rainfall time series were created by increasingly degrading observed data (proxy for a `perfect forecast') from 0 % to +/-50 % error. For the second objective, three different methods were used to disaggregate monthly rainfall data into daily time series. These were used to force a simple lumped hydrological model (GR4J) to generate streamflow predictions at a one-month lead time for over 300 catchments

  18. The Effects of Volcano-Induced Ozone Depletion on Short-lived Climate Forcing in the Arctic

    Science.gov (United States)

    Ward, P. L.

    2012-12-01

    Photodissociation of oxygen maintains the stratopause ~50°C warmer than the tropopause. Photodissociation of ozone warms the lower stratosphere, preventing most of this high-energy DNA-damaging solar radiation from reaching the troposphere. Ozone depletion allows more UV energy to reach the lower troposphere causing photodissociation of anthropogenic ozone and nitrogen dioxide. UV energy also penetrates the ocean >10 m where it is absorbed more efficiently than infrared radiation that barely penetrates the surface. Manmade chlorofluorocarbons caused ozone depletion from 1965 to 1994 with slow recovery predicted over the next 50+ years. But the lowest levels of ozone followed the eruptions of Pinatubo (1991 VEI=6), Eyjafjallajökull (2010 VEI=4), and Grímsvötn (2011 VEI=4). Each of the relatively small, basaltic eruptions in Iceland caused more ozone depletion than the long-term effects of chlorofluorocarbons, although total ozone appears to return to pre-eruption levels within a decade. Ozone depletion by 20% increases energy flux thru the lowermost troposphere by 0.7 W m-2 for overhead sun causing temperatures in the lower stratosphere to drop >2°C since 1958 in steps after the 3 largest volcanic eruptions: Agung 1963, El Chichón 1982, and Pinatubo. Temperatures at the surface increased primarily in the regions and at the times of the greatest observed ozone depletion. The greatest warming observed was along the Western Antarctic Peninsula (65.4°S) where minimum temperatures rose 6.7°C from 1951 to 2003 while maximum temperatures remained relatively constant. Minimum total column ozone in September-October was 40-56% lower than in 1972 almost every year since 1987, strongly anti-correlated with observed minimum temperatures. Sea ice decreased 10%, 7 ice shelves separated, 87% of the glaciers retreated and the Antarctic Circumpolar Current warmed. Elsewhere under the ozone hole, warming of continental Antarctica was limited by the high albedo (0.86) of

  19. Internal and external North Atlantic Sector variability in the Kiel climate model

    Energy Technology Data Exchange (ETDEWEB)

    Latif, Mojib; Park, Wonsun; Ding, Hui; Keenlyside, Noel S. [Leibniz-Inst. fuer Meereswissenschaften, Kiel (Germany)

    2009-08-15

    The internal and external North Atlantic Sector variability is investigated by means of a multimillennial control run and forced experiments with the Kiel Climate Model (KCM). The internal variability is studied by analyzing the control run. The externally forced variability is investigated in a run with periodic millennial solar forcing and in greenhouse warming experiments with enhanced carbon dioxide concentrations. The surface air temperature (SAT) averaged over the Northern Hemisphere simulated in the control run displays enhanced variability relative to the red background at decadal, centennial, and millennial timescales. Special emphasis is given to the variability of the Meridional Overturning Circulation (MOC). The MOC plays an important role in the generation of internal climate modes. Furthermore, the MOC provides a strong negative feedback on the Northern Hemisphere SAT in both the solar and greenhouse warming experiments, thereby moderating the direct effects of the external forcing in the North Atlantic. The implications of the results for decadal predictability are discussed. (orig.)

  20. Response of a comprehensive climate model to a broad range of external forcings: relevance for deep ocean ventilation and the development of late Cenozoic ice ages

    Science.gov (United States)

    Galbraith, Eric; de Lavergne, Casimir

    2018-03-01

    Over the past few million years, the Earth descended from the relatively warm and stable climate of the Pliocene into the increasingly dramatic ice age cycles of the Pleistocene. The influences of orbital forcing and atmospheric CO2 on land-based ice sheets have long been considered as the key drivers of the ice ages, but less attention has been paid to their direct influences on the circulation of the deep ocean. Here we provide a broad view on the influences of CO2, orbital forcing and ice sheet size according to a comprehensive Earth system model, by integrating the model to equilibrium under 40 different combinations of the three external forcings. We find that the volume contribution of Antarctic (AABW) vs. North Atlantic (NADW) waters to the deep ocean varies widely among the simulations, and can be predicted from the difference between the surface densities at AABW and NADW deep water formation sites. Minima of both the AABW-NADW density difference and the AABW volume occur near interglacial CO2 (270-400 ppm). At low CO2, abundant formation and northward export of sea ice in the Southern Ocean contributes to very salty and dense Antarctic waters that dominate the global deep ocean. Furthermore, when the Earth is cold, low obliquity (i.e. a reduced tilt of Earth's rotational axis) enhances the Antarctic water volume by expanding sea ice further. At high CO2, AABW dominance is favoured due to relatively warm subpolar North Atlantic waters, with more dependence on precession. Meanwhile, a large Laurentide ice sheet steers atmospheric circulation as to strengthen the Atlantic Meridional Overturning Circulation, but cools the Southern Ocean remotely, enhancing Antarctic sea ice export and leading to very salty and expanded AABW. Together, these results suggest that a `sweet spot' of low CO2, low obliquity and relatively small ice sheets would have poised the AMOC for interruption, promoting Dansgaard-Oeschger-type abrupt change. The deep ocean temperature and

  1. Aerosol optical properties and radiative forcing in the high Himalaya based on measurements at the Nepal Climate Observatory-Pyramid site (5079 m a.s.l.

    Directory of Open Access Journals (Sweden)

    S. Marcq

    2010-07-01

    Full Text Available Intense anthropogenic emissions over the Indian sub-continent lead to the formation of layers of particulate pollution that can be transported to the high altitude regions of the Himalaya-Hindu-Kush (HKH. Aerosol particles contain a substantial fraction of strongly absorbing material, including black carbon (BC, organic compounds (OC, and dust all of which can contribute to atmospheric warming, in addition to greenhouse gases. Using a 3-year record of continuous measurements of aerosol optical properties, we present a time series of key climate relevant aerosol properties including the aerosol absorption (σap and scattering (σsp coefficients as well as the single-scattering albedo (w0. Results of this investigation show substantial seasonal variability of these properties, with long range transport during the pre- and post-monsoon seasons and efficient precipitation scavenging of aerosol particles during the monsoon season. The monthly averaged scattering coefficients range from 0.1 Mm−1 (monsoon to 20 Mm−1 while the average absorption coefficients range from 0.5 Mm−1 to 3.5 Mm−1. Both have their maximum values during the pre-monsoon period (April and reach a minimum during Monsoon (July–August. This leads to dry w0 values from 0.86 (pre-monsoon to 0.79 (monsoon seasons. Significant diurnal variability due to valley wind circulation is also reported. Using aerosol optical depth (AOD measurements, we calculated the resulting direct local radiative forcing due to aerosols for selected air mass cases. We found that the presence of absorbing particulate material can locally induce an additional top of the atmosphere (TOA forcing of 10 to 20 W m−2 for the first atmospheric layer (500 m above surface. The TOA positive forcing depends on the presence of snow at the surface, and takes place preferentially during episodes of

  2. Carbon dioxide as chemical feedstock

    National Research Council Canada - National Science Library

    Aresta, M

    2010-01-01

    ... Dioxide as an Inert Solvent for Chemical Syntheses 15 Alessandro Galia and Giuseppe Filardo Introduction 15 Dense Carbon Dioxide as Solvent Medium for Chemical Processes 15 Enzymatic Catalysis in Dense Carbon Dioxide 18 Other Reactions in Dense Carbon Dioxide 19 Polymer Synthesis in Supercritical Carbon Dioxide 20 Chain Polymerizations: Synt...

  3. The Relationship Between Radiative Forcing and Temperature. What Do Statistical Analyses of the Instrumental Temperature Record Measure?

    International Nuclear Information System (INIS)

    Kaufmann, R.K.; Kauppi, H.; Stock, J.H.

    2006-01-01

    Comparing statistical estimates for the long-run temperature effect of doubled CO2 with those generated by climate models begs the question, is the long-run temperature effect of doubled CO2 that is estimated from the instrumental temperature record using statistical techniques consistent with the transient climate response, the equilibrium climate sensitivity, or the effective climate sensitivity. Here, we attempt to answer the question, what do statistical analyses of the observational record measure, by using these same statistical techniques to estimate the temperature effect of a doubling in the atmospheric concentration of carbon dioxide from seventeen simulations run for the Coupled Model Intercomparison Project 2 (CMIP2). The results indicate that the temperature effect estimated by the statistical methodology is consistent with the transient climate response and that this consistency is relatively unaffected by sample size or the increase in radiative forcing in the sample

  4. Evaluation of preindustrial to present-day black carbon and its albedo forcing from Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP

    Directory of Open Access Journals (Sweden)

    Y. H. Lee

    2013-03-01

    Full Text Available As part of the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP, we evaluate the historical black carbon (BC aerosols simulated by 8 ACCMIP models against observations including 12 ice core records, long-term surface mass concentrations, and recent Arctic BC snowpack measurements. We also estimate BC albedo forcing by performing additional simulations using offline models with prescribed meteorology from 1996–2000. We evaluate the vertical profile of BC snow concentrations from these offline simulations using the recent BC snowpack measurements. Despite using the same BC emissions, the global BC burden differs by approximately a factor of 3 among models due to differences in aerosol removal parameterizations and simulated meteorology: 34 Gg to 103 Gg in 1850 and 82 Gg to 315 Gg in 2000. However, the global BC burden from preindustrial to present-day increases by 2.5–3 times with little variation among models, roughly matching the 2.5-fold increase in total BC emissions during the same period. We find a large divergence among models at both Northern Hemisphere (NH and Southern Hemisphere (SH high latitude regions for BC burden and at SH high latitude regions for deposition fluxes. The ACCMIP simulations match the observed BC surface mass concentrations well in Europe and North America except at Ispra. However, the models fail to predict the Arctic BC seasonality due to severe underestimations during winter and spring. The simulated vertically resolved BC snow concentrations are, on average, within a factor of 2–3 of the BC snowpack measurements except for Greenland and the Arctic Ocean. For the ice core evaluation, models tend to adequately capture both the observed temporal trends and the magnitudes at Greenland sites. However, models fail to predict the decreasing trend of BC depositions/ice core concentrations from the 1950s to the 1970s in most Tibetan Plateau ice cores. The distinct temporal trend at the Tibetan

  5. Evaluation of preindustrial to present-day black carbon and its albedo forcing from Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP)

    Science.gov (United States)

    Lee, Y. H.; Lamarque, J.-F.; Flanner, M. G.; Jiao, C.; Shindell, D. T.; Bernsten, T.; Bisiaux, M. M.; Cao, J.; Collins, W. J.; Curran, M.; hide

    2013-01-01

    As part of the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP), we evaluate the historical black carbon (BC) aerosols simulated by 8 ACCMIP models against observations including 12 ice core records, long-term surface mass concentrations, and recent Arctic BC snowpack measurements. We also estimate BC albedo forcing by performing additional simulations using offline models with prescribed meteorology from 1996-2000. We evaluate the vertical profile of BC snow concentrations from these offline simulations using the recent BC snowpack measurements. Despite using the same BC emissions, the global BC burden differs by approximately a factor of 3 among models due to differences in aerosol removal parameterizations and simulated meteorology: 34 Gg to 103 Gg in 1850 and 82 Gg to 315 Gg in 2000. However, the global BC burden from preindustrial to present-day increases by 2.5-3 times with little variation among models, roughly matching the 2.5-fold increase in total BC emissions during the same period.We find a large divergence among models at both Northern Hemisphere (NH) and Southern Hemisphere (SH) high latitude regions for BC burden and at SH high latitude regions for deposition fluxes. The ACCMIP simulations match the observed BC surface mass concentrations well in Europe and North America except at Ispra. However, the models fail to predict the Arctic BC seasonality due to severe underestimations during winter and spring. The simulated vertically resolved BC snow concentrations are, on average, within a factor of 2-3 of the BC snowpack measurements except for Greenland and the Arctic Ocean. For the ice core evaluation, models tend to adequately capture both the observed temporal trends and the magnitudes at Greenland sites. However, models fail to predict the decreasing trend of BC depositions/ice core concentrations from the 1950s to the 1970s in most Tibetan Plateau ice cores. The distinct temporal trend at the Tibetan Plateau ice cores

  6. Time-dependent climate benefits of using forest residues to substitute fossil fuels

    International Nuclear Information System (INIS)

    Sathre, Roger; Gustavsson, Leif

    2011-01-01

    In this study we analyze and compare the climate impacts from the recovery, transport and combustion of forest residues (harvest slash and stumps), versus the climate impacts that would have occurred if the residues were left in the forest and fossil fuels used instead. We use cumulative radiative forcing (CRF) as an indicator of climate impacts, and we explicitly consider the temporal dynamics of atmospheric carbon dioxide and biomass decomposition. Over a 240-year period, we find that CRF is significantly reduced when forest residues are used instead of fossil fuels. The type of fossil fuel replaced is important, with coal replacement giving the greatest CRF reduction. Replacing oil and fossil gas also gives long-term CRF reduction, although CRF is positive during the first 10-25 years when these fuels are replaced. Biomass productivity is also important, with more productive forests giving greater CRF reduction per hectare. The decay rate for biomass left in the forest is found to be less significant. Fossil energy inputs for biomass recovery and transport have very little impact on CRF. -- Highlights: → Cumulative radiative forcing (CRF) can measure climate impacts of dynamic systems. → Climate impact is reduced when forest slash and stumps are used to replace fossil fuels. → Forest biofuels may cause short-term climate impact, followed by long-term climate benefit. → Forest residues should replace coal to avoid short-term climate impact. → Fossil energy used for biofuel recovery and transport has very little climate impact.

  7. Overview of the Chemistry-Aerosol Mediterranean Experiment/Aerosol Direct Radiative Forcing on the Mediterranean Climate (ChArMEx/ADRIMED summer 2013 campaign

    Directory of Open Access Journals (Sweden)

    M. Mallet

    2016-01-01

    direct forcing, in situ surface and aircraft observations have been merged and used as inputs in 1-D radiative transfer codes for calculating the aerosol direct radiative forcing (DRF. Results show significant surface SW instantaneous forcing (up to −90 W m−2 at noon. Aircraft observations provide also original estimates of the vertical structure of SW and LW radiative heating revealing significant instantaneous values of about 5° K per day in the solar spectrum (for a solar angle of 30° within the dust layer. Associated 3-D modeling studies from regional climate (RCM and chemistry transport (CTM models indicate a relatively good agreement for simulated AOD compared with observations from the AERONET/PHOTONS network and satellite data, especially for long-range dust transport. Calculations of the 3-D SW (clear-sky surface DRF indicate an average of about −10 to −20 W m−2 (for the whole period over the Mediterranean Sea together with maxima (−50 W m−2 over northern Africa. The top of the atmosphere (TOA DRF is shown to be highly variable within the domain, due to moderate absorbing properties of dust and changes in the surface albedo. Indeed, 3-D simulations indicate negative forcing over the Mediterranean Sea and Europe and positive forcing over northern Africa. Finally, a multi-year simulation, performed for the 2003 to 2009 period and including an ocean–atmosphere (O–A coupling, underlines the impact of the aerosol direct radiative forcing on the sea surface temperature, O–A fluxes and the hydrological cycle over the Mediterranean.

  8. Uranium dioxide pellets

    International Nuclear Information System (INIS)

    Zawidzki, T.W.

    1979-01-01

    Sintered uranium dioxide pellets composed of particles of size > 50 microns suitable for power reactor use are made by incorporating a small amount of sulphur into the uranium dioxide before sintering. The increase in grain size achieved results in an improvement in overall efficiency when such pellets are used in a power reactor. (author)

  9. Classification of titanium dioxide

    International Nuclear Information System (INIS)

    Macias B, L.R.; Garcia C, R.M.; Maya M, M.E.; Ita T, A. De; Palacios G, J.

    2002-01-01

    In this work the X-ray diffraction (XRD), Scanning Electron Microscopy (Sem) and the X-ray Dispersive Energy Spectroscopy techniques are used with the purpose to achieve a complete identification of phases and mixture of phases of a crystalline material as titanium dioxide. The problem for solving consists of being able to distinguish a sample of titanium dioxide being different than a titanium dioxide pigment. A standard sample of titanium dioxide with NIST certificate is used, which indicates a purity of 99.74% for the TiO 2 . The following way is recommended to proceed: a)To make an analysis by means of X-ray diffraction technique to the sample of titanium dioxide pigment and on the standard of titanium dioxide waiting not find differences. b) To make a chemical analysis by the X-ray Dispersive Energy Spectroscopy via in a microscope, taking advantage of the high vacuum since it is oxygen which is analysed and if it is concluded that the aluminium oxide appears in a greater proportion to 1% it is established that is a titanium dioxide pigment, but if it is lesser then it will be only titanium dioxide. This type of analysis is an application of the nuclear techniques useful for the tariff classification of merchandise which is considered as of difficult recognition. (Author)

  10. Climate change, pink salmon, and the nexus between bottom-up and top-down forcing in the subarctic Pacific Ocean and Bering Sea.

    Science.gov (United States)

    Springer, Alan M; van Vliet, Gus B

    2014-05-06

    Climate change in the last century was associated with spectacular growth of many wild Pacific salmon stocks in the North Pacific Ocean and Bering Sea, apparently through bottom-up forcing linking meteorology to ocean physics, water temperature, and plankton production. One species in particular, pink salmon, became so numerous by the 1990s that they began to dominate other species of salmon for prey resources and to exert top-down control in the open ocean ecosystem. Information from long-term monitoring of seabirds in the Aleutian Islands and Bering Sea reveals that the sphere of influence of pink salmon is much larger than previously known. Seabirds, pink salmon, other species of salmon, and by extension other higher-order predators, are tightly linked ecologically and must be included in international management and conservation policies for sustaining all species that compete for common, finite resource pools. These data further emphasize that the unique 2-y cycle in abundance of pink salmon drives interannual shifts between two alternate states of a complex marine ecosystem.

  11. Anthropogenic sulfur dioxide emissions: 1850–2005

    Directory of Open Access Journals (Sweden)

    S. J. Smith

    2011-02-01

    Full Text Available Sulfur aerosols impact human health, ecosystems, agriculture, and global and regional climate. A new annual estimate of anthropogenic global and regional sulfur dioxide emissions has been constructed spanning the period 1850–2005 using a bottom-up mass balance method, calibrated to country-level inventory data. Global emissions peaked in the early 1970s and decreased until 2000, with an increase in recent years due to increased emissions in China, international shipping, and developing countries in general. An uncertainty analysis was conducted including both random and systemic uncertainties. The overall global uncertainty in sulfur dioxide emissions is relatively small, but regional uncertainties ranged up to 30%. The largest contributors to uncertainty at present are emissions from China and international shipping. Emissions were distributed on a 0.5° grid by sector for use in coordinated climate model experiments.

  12. Visual and reversible carbon dioxide sensing enabled by doctor blade coated macroporous photonic crystals.

    Science.gov (United States)

    Lin, Yi-Han; Suen, Shing-Yi; Yang, Hongta

    2017-11-15

    With significant impacts of carbon dioxide on global climate change, carbon dioxide sensing is of great importance. However, most of the existing sensing technologies are prone to interferences from carbon monoxide, or suffer from the use of sophisticated instruments. This research reports the development of reproducible carbon dioxide sensor using roll-to-roll compatible doctor blade coated three-dimensional macroporous photonic crystals. The pores are functionalized with amine groups to allow the reaction with carbon dioxide in the presence of humidity. The adsorption of carbon dioxide leads to red-shift and amplitude reduction of the optical stop bands, resulting in carbon dioxide detection with visible readout. The dependences of the diffraction wavelength on carbon dioxide partial pressure for various amine-functionalized photonic crystals and different humidities in the environment are systematically investigated. In addition, the reproducibility of carbon dioxide sensing has also been demonstrated in this research. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. Impacts of climate change on the global forest sector

    Science.gov (United States)

    Perez-Garcia, J.; Joyce, L.A.; McGuire, A.D.; Xiao, X.

    2002-01-01

    The path and magnitude of future anthropogenic emissions of carbon dioxide will likely influence changes in climate that may impact the global forest sector. These responses in the global forest sector may have implications for international efforts to stabilize the atmospheric concentration of carbon dioxide. This study takes a step toward including the role of global forest sector in integrated assessments of the global carbon cycle by linking global models of climate dynamics, ecosystem processes and forest economics to assess the potential responses of the global forest sector to different levels of greenhouse gas emissions. We utilize three climate scenarios and two economic scenarios to represent a range of greenhouse gas emissions and economic behavior. At the end of the analysis period (2040), the potential responses in regional forest growing stock simulated by the global ecosystem model range from decreases and increases for the low emissions climate scenario to increases in all regions for the high emissions climate scenario. The changes in vegetation are used to adjust timber supply in the softwood and hardwood sectors of the economic model. In general, the global changes in welfare are positive, but small across all scenarios. At the regional level, the changes in welfare can be large and either negative or positive. Markets and trade in forest products play important roles in whether a region realizes any gains associated with climate change. In general, regions with the lowest wood fiber production cost are able to expand harvests. Trade in forest products leads to lower prices elsewhere. The low-cost regions expand market shares and force higher-cost regions to decrease their harvests. Trade produces different economic gains and losses across the globe even though, globally, economic welfare increases. The results of this study indicate that assumptions within alternative climate scenarios and about trade in forest products are important factors

  14. Low-frequency and high-frequency changes in temperature and effective humidity during the Holocene in south-central Sweden: implications for atmospheric and oceanic forcings of climate

    Energy Technology Data Exchange (ETDEWEB)

    Seppae, H. [University of Helsinki, Department of Geology, 64, Helsinki (Finland); Hammarlund, D. [Lund University, GeoBiosphere Science Centre, Quaternary Sciences, Lund (Sweden); Antonsson, K. [Uppsala University, Department of Earth Sciences, Uppsala (Sweden)

    2005-08-01

    An integrated use of independent palaeoclimatological proxy techniques that reflect different components of the climate system provides a potential key for functional analysis of past climate changes. Here we report a 10,000 year quantitative record of annual mean temperature (T{sub ann}), based on pollen-climate transfer functions and pollen-stratigraphical data from Lake Flarken, south-central Sweden. The pollen-based temperature reconstruction is compared with a reconstruction of effective humidity, as reflected by a {delta}{sup 18}O record obtained on stratigraphy of lacustrine carbonates from Lake Igelsjoen, c. 10 km from Lake Flarken, which gives evidence of pronounced changes in effective humidity. The relatively low T{sub ann}, and high effective humidity as reflected by a low evaporation/inflow ratio suggest a maritime early Holocene climate (10,000-8,300 cal year BP), seemingly incompatible with the highly seasonal solar insolation configuration. We argue that the maritime climate was due to the stronger-than-present zonal flow, enhanced by the high early Holocene sea-surface temperatures in the North Atlantic. The maritime climate mode was disrupted by the abrupt cold event at 8,200 cal year BP, followed at 8,000 cal year BP by a stable Holocene Thermal Maximum. The latter was characterized by T{sub ann} values about 2.5 C higher than at present and markedly dry conditions, indicative of stable summer-time anti-cyclonic circulation, possibly corresponding with modern blocking anticyclonic conditions. The last 4,300 year period is characterized by an increasingly cold, moist, and unstable climate. The results demonstrate the value of combining two independent palaeoclimatic proxies in enhancing the reliability, generality, and interpretability of the palaeoclimatic results. Further methodological refinements especially in resolving past seasonal climatic contrasts are needed to better understand the role of different forcing factors in driving millennial

  15. Electrochemical processing of carbon dioxide.

    Science.gov (United States)

    Oloman, Colin; Li, Hui

    2008-01-01

    With respect to the negative role of carbon dioxide on our climate, it is clear that the time is ripe for the development of processes that convert CO(2) into useful products. The electroreduction of CO(2) is a prime candidate here, as the reaction at near-ambient conditions can yield organics such as formic acid, methanol, and methane. Recent laboratory work on the 100 A scale has shown that reduction of CO(2) to formate (HCO(2)(-)) may be carried out in a trickle-bed continuous electrochemical reactor under industrially viable conditions. Presuming the problems of cathode stability and formate crossover can be overcome, this type of reactor is proposed as the basis for a commercial operation. The viability of corresponding processes for electrosynthesis of formate salts and/or formic acid from CO(2) is examined here through conceptual flowsheets for two process options, each converting CO(2) at the rate of 100 tonnes per day.

  16. Large contribution of natural aerosols to uncertainty in indirect forcing

    Science.gov (United States)

    Carslaw, K. S.; Lee, L. A.; Reddington, C. L.; Pringle, K. J.; Rap, A.; Forster, P. M.; Mann, G. W.; Spracklen, D. V.; Woodhouse, M. T.; Regayre, L. A.; Pierce, J. R.

    2013-11-01

    The effect of anthropogenic aerosols on cloud droplet concentrations and radiative properties is the source of one of the largest uncertainties in the radiative forcing of climate over the industrial period. This uncertainty affects our ability to estimate how sensitive the climate is to greenhouse gas emissions. Here we perform a sensitivity analysis on a global model to quantify the uncertainty in cloud radiative forcing over the industrial period caused by uncertainties in aerosol emissions and processes. Our results show that 45 per cent of the variance of aerosol forcing since about 1750 arises from uncertainties in natural emissions of volcanic sulphur dioxide, marine dimethylsulphide, biogenic volatile organic carbon, biomass burning and sea spray. Only 34 per cent of the variance is associated with anthropogenic emissions. The results point to the importance of understanding pristine pre-industrial-like environments, with natural aerosols only, and suggest that improved measurements and evaluation of simulated aerosols in polluted present-day conditions will not necessarily result in commensurate reductions in the uncertainty of forcing estimates.

  17. Large contribution of natural aerosols to uncertainty in indirect forcing.

    Science.gov (United States)

    Carslaw, K S; Lee, L A; Reddington, C L; Pringle, K J; Rap, A; Forster, P M; Mann, G W; Spracklen, D V; Woodhouse, M T; Regayre, L A; Pierce, J R

    2013-11-07

    The effect of anthropogenic aerosols on cloud droplet concentrations and radiative properties is the source of one of the largest uncertainties in the radiative forcing of climate over the industrial period. This uncertainty affects our ability to estimate how sensitive the climate is to greenhouse gas emissions. Here we perform a sensitivity analysis on a global model to quantify the uncertainty in cloud radiative forcing over the industrial period caused by uncertainties in aerosol emissions and processes. Our results show that 45 per cent of the variance of aerosol forcing since about 1750 arises from uncertainties in natural emissions of volcanic sulphur dioxide, marine dimethylsulphide, biogenic volatile organic carbon, biomass burning and sea spray. Only 34 per cent of the variance is associated with anthropogenic emissions. The results point to the importance of understanding pristine pre-industrial-like environments, with natural aerosols only, and suggest that improved measurements and evaluation of simulated aerosols in polluted present-day conditions will not necessarily result in commensurate reductions in the uncertainty of forcing estimates.

  18. Evaluation of Preindustrial to Present-day Black Carbon and its Albedo Forcing from Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP)

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Y. H.; Lamarque, J.-F.; Flanner, M. G.; Jiao, C.; Shindell, Drew; Berntsen, T.; Bisiauxs, M.; Cao, J.; Collins, W. J.; Curran, M.; Edwards, R.; Faluvegi, G.; Ghan, Steven J.; Horowitz, L.; McConnell, J.R.; Ming, J.; Myhre, G.; Nagashima, T.; Naik, Vaishali; Rumbold, S.; Skeie, R. B.; Sudo, K.; Takemura, T.; Thevenon, F.; Xu, B.; Yoon, Jin-Ho

    2013-03-05

    As a part of the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP), we evaluate the historical black carbon (BC) aerosols simulated by 8 ACCMIP models against the observations including 12 ice core records, a long-term surface mass concentrations and recent Arctic BC snowpack measurements. We also estimate BC albedo forcing by performing additional simulations using the NCAR Community Land and Sea-Ice model 4 with prescribed meteorology from 1996-2000, which includes the SNICAR BC-snow model. We evaluated the vertical profile of BC snow concentrations from these offline simulations to using recent BC snowpack measurements. Despite using the same BC emissions, global BC burden differs by approximately a factor of 3 among models due to the differences in aerosol removal parameterizations and simulated meteorology among models; 34 Gg to 103 Gg in 1850 and 82 Gg to 315 Gg in 2000. However,models agree well on 2.5~3 times increase in the global BC burden from preindustrial to present-day, which matches with the 2.5 times increase in BC emissions. We find a large model diversity at both NH and SH high latitude regions for BC burden and at SH high latitude regions for deposition fluxes. The ACCMIP simulations match the observed BC mass concentrations well in Europe and North America except at Jungfrauch and Ispra. However, the models fail to capture the Arctic BC seasonality due tosevere underestimations during winter and spring. Compared to recent snowpack measurements, the simulated vertically resolved BC snow concentrations are, on average, within a factor of 2-3 of observations except for Greenland and Arctic Ocean. However, model and observation differ widely due to missing interannual variations in emissions and possibly due to the choice of the prescribed meteorology period (i.e., 1996-2000).

  19. Uranium dioxide. Sintering test

    International Nuclear Information System (INIS)

    Anon.

    Description of a sintering method and of the equipment devoted to uranium dioxide powder caracterization and comparison between different samples. Determination of the curve giving specific volume versus pressure and micrographic examination of a pellet at medium pressure [fr

  20. Collaborative Research. Quantifying Climate Feedbacks of the Terrestrial Biosphere under Thawing Permafrost Conditions in the Arctic

    Energy Technology Data Exchange (ETDEWEB)

    Zhuang, Qianlai [Purdue Univ., West Lafayette, IN (United States); Schlosser, Courtney [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Melillo, Jerry [Marine Biological Lab. (MBL), Woods Hole, MA (United States); Walter, Katey [Univ. of Alaska, Fairbanks, AK (United States)

    2015-09-15

    Our overall goal is to quantify the potential for threshold changes in natural emission rates of trace gases, particularly methane and carbon dioxide, from pan-arctic terrestrial systems under the spectrum of anthropogenically-forced climate warming, and the conditions under which these emissions provide a strong feedback mechanism to global climate warming. This goal is motivated under the premise that polar amplification of global climate warming will induce widespread thaw and degradation of the permafrost, and would thus cause substantial changes to the landscape of wetlands and lakes, especially thermokarst (thaw) lakes, across the Arctic. Through a suite of numerical experiments that encapsulate the fundamental processes governing methane emissions and carbon exchanges – as well as their coupling to the global climate system - we intend to test the following hypothesis in the proposed research: There exists a climate warming threshold beyond which permafrost degradation becomes widespread and stimulates large increases in methane emissions (via thermokarst lakes and poorly-drained wetland areas upon thawing permafrost along with microbial metabolic responses to higher temperatures) and increases in carbon dioxide emissions from well-drained areas. Besides changes in biogeochemistry, this threshold will also influence global energy dynamics through effects on surface albedo, evapotranspiration and water vapor. These changes would outweigh any increased uptake of carbon (e.g. from peatlands and higher plant photosynthesis) and would result in a strong, positive feedback to global climate warming.

  1. Climate control of terrestrial carbon exchange across biomes and continents

    NARCIS (Netherlands)

    Yi, C.; Ricciuto, D.; Li, R.; Hendriks, D.M.D.; Moors, E.J.; Valentini, R.

    2010-01-01

    Understanding the relationships between climate and carbon exchange by terrestrial ecosystems is critical to predict future levels of atmospheric carbon dioxide because of the potential accelerating effects of positive climate-carbon cycle feedbacks. However, directly observed relationships between

  2. A commentary on the Atlantic meridional overturning circulation stability in climate models

    Science.gov (United States)

    Gent, Peter R.

    2018-02-01

    The stability of the Atlantic meridional overturning circulation (AMOC) in ocean models depends quite strongly on the model formulation, especially the vertical mixing, and whether it is coupled to an atmosphere model. A hysteresis loop in AMOC strength with respect to freshwater forcing has been found in several intermediate complexity climate models and in one fully coupled climate model that has very coarse resolution. Over 40% of modern climate models are in a bistable AMOC state according to the very frequently used simple stability criterion which is based solely on the sign of the AMOC freshwater transport across 33° S. In a recent freshwater hosing experiment in a climate model with an eddy-permitting ocean component, the change in the gyre freshwater transport across 33° S is larger than the AMOC freshwater transport change. This casts very strong doubt on the usefulness of this simple AMOC stability criterion. If a climate model uses large surface flux adjustments, then these adjustments can interfere with the atmosphere-ocean feedbacks, and strongly change the AMOC stability properties. AMOC can be shut off for many hundreds of years in modern fully coupled climate models if the hosing or carbon dioxide forcing is strong enough. However, in one climate model the AMOC recovers after between 1000 and 1400 years. Recent 1% increasing carbon dioxide runs and RCP8.5 future scenario runs have shown that the AMOC reduction is smaller using an eddy-resolving ocean component than in the comparable standard 1° ocean climate models.

  3. Integrated Assessment of Carbon Dioxide Removal

    Science.gov (United States)

    Rickels, W.; Reith, F.; Keller, D.; Oschlies, A.; Quaas, M. F.

    2018-03-01

    To maintain the chance of keeping the average global temperature increase below 2°C and to limit long-term climate change, removing carbon dioxide from the atmosphere (carbon dioxide removal, CDR) is becoming increasingly necessary. We analyze optimal and cost-effective climate policies in the dynamic integrated assessment model (IAM) of climate and the economy (DICE2016R) and investigate (1) the utilization of (ocean) CDR under different climate objectives, (2) the sensitivity of policies with respect to carbon cycle feedbacks, and (3) how well carbon cycle feedbacks are captured in the carbon cycle models used in state-of-the-art IAMs. Overall, the carbon cycle model in DICE2016R shows clear improvements compared to its predecessor, DICE2013R, capturing much better long-term dynamics and also oceanic carbon outgassing due to excess oceanic storage of carbon from CDR. However, this comes at the cost of a (too) tight short-term remaining emission budget, limiting the model suitability to analyze low-emission scenarios accurately. With DICE2016R, the compliance with the 2°C goal is no longer feasible without negative emissions via CDR. Overall, the optimal amount of CDR has to take into account (1) the emission substitution effect and (2) compensation for carbon cycle feedbacks.

  4. Climate change reference guide

    Science.gov (United States)

    2009-01-01

    At the heart of climate change is the greenhouse effect, in which molecules of various gases trap heat in Earths atmosphere and keep it warm enough to support life. Carbon dioxide and other greenhouse gases (GHGs) are an important part of Ea...

  5. Plio-Pleistocene climate sensitivity evaluated using high-resolution CO2 records

    Science.gov (United States)

    Martínez-Botí, M. A.; Foster, G. L.; Chalk, T. B.; Rohling, E. J.; Sexton, P. F.; Lunt, D. J.; Pancost, R. D.; Badger, M. P. S.; Schmidt, D. N.

    2015-02-01

    Theory and climate modelling suggest that the sensitivity of Earth's climate to changes in radiative forcing could depend on the background climate. However, palaeoclimate data have thus far been insufficient to provide a conclusive test of this prediction. Here we present atmospheric carbon dioxide (CO2) reconstructions based on multi-site boron-isotope records from the late Pliocene epoch (3.3 to 2.3 million years ago). We find that Earth's climate sensitivity to CO2-based radiative forcing (Earth system sensitivity) was half as strong during the warm Pliocene as during the cold late Pleistocene epoch (0.8 to 0.01 million years ago). We attribute this difference to the radiative impacts of continental ice-volume changes (the ice-albedo feedback) during the late Pleistocene, because equilibrium climate sensitivity is identical for the two intervals when we account for such impacts using sea-level reconstructions. We conclude that, on a global scale, no unexpected climate feedbacks operated during the warm Pliocene, and that predictions of equilibrium climate sensitivity (excluding long-term ice-albedo feedbacks) for our Pliocene-like future (with CO2 levels up to maximum Pliocene levels of 450 parts per million) are well described by the currently accepted range of an increase of 1.5 K to 4.5 K per doubling of CO2.

  6. Plio-Pleistocene climate sensitivity evaluated using high-resolution CO2 records.

    Science.gov (United States)

    Martínez-Botí, M A; Foster, G L; Chalk, T B; Rohling, E J; Sexton, P F; Lunt, D J; Pancost, R D; Badger, M P S; Schmidt, D N

    2015-02-05

    Theory and climate modelling suggest that the sensitivity of Earth's climate to changes in radiative forcing could depend on the background climate. However, palaeoclimate data have thus far been insufficient to provide a conclusive test of this prediction. Here we present atmospheric carbon dioxide (CO2) reconstructions based on multi-site boron-isotope records from the late Pliocene epoch (3.3 to 2.3 million years ago). We find that Earth's climate sensitivity to CO2-based radiative forcing (Earth system sensitivity) was half as strong during the warm Pliocene as during the cold late Pleistocene epoch (0.8 to 0.01 million years ago). We attribute this difference to the radiative impacts of continental ice-volume changes (the ice-albedo feedback) during the late Pleistocene, because equilibrium climate sensitivity is identical for the two intervals when we account for such impacts using sea-level reconstructions. We conclude that, on a global scale, no unexpected climate feedbacks operated during the warm Pliocene, and that predictions of equilibrium climate sensitivity (excluding long-term ice-albedo feedbacks) for our Pliocene-like future (with CO2 levels up to maximum Pliocene levels of 450 parts per million) are well described by the currently accepted range of an increase of 1.5 K to 4.5 K per doubling of CO2.

  7. Effects of climatic variability and change

    Science.gov (United States)

    Michael G. Ryan; James M. Vose

    2012-01-01

    Climate profoundly shapes forests. Forest species composition, productivity, availability of goods and services, disturbance regimes, and location on the landscape are all regulated by climate. Much research attention has focused on the problem of projecting the response of forests to changing climate, elevated atmospheric carbon dioxide (CO2)...

  8. Organic matter recycling in a shallow coastal zone (NW Mediterranean): The influence of local and global climatic forcing and organic matter lability on hydrolytic enzyme activity

    Science.gov (United States)

    Misic, Cristina; Harriague, Anabella Covazzi

    2008-12-01

    Seawater and sediment were collected on a monthly basis from a shallow (10.5 m depth) coastal site in the Ligurian Sea (NW Mediterranean) from November 1993 to December 1994 to determine the main environmental forces that influenced the biogeochemical processes and to study the relationships between the availability and lability of the organic matter (OM) and hydrolytic enzymatic activity. The current direction throughout the sampling year was influenced by the climatic conditions, which showed significant correlations with north atlantic oscillation (NAO) index values. The current generally flowed northwards in spring. This could cause significantly lower transparency values than in the summer, when an eastward current probably reduced the allochthonous input of material from the main local watercourse and contributed to turning the conditions from mesotrophic to oligotrophic. Spring and summer were separated by transitional periods more than by the canonical autumn and winter seasons. These transitions were characterised by a reduction in salinity values and by resuspension caused by water column mixing and a current flowing towards the southwest. The significant inverse correlations of the chlorophyll- a and protein concentrations, bacterial abundance and proteolysis of the bottom seawater and transparency showed the direct influence of resuspension on the organic matter dynamics. Moreover, OM trophic quality influenced the bacterial parameters and the enzymatic activities. The glycolytic β glucosidase and chitinase activities and their bacterial cell-specific hydrolytic rates were higher when substrates such as hydrolysable proteins were available, while they decreased when refractory compounds were abundant. The low leucine aminopeptidase: β glucosidase ratio values observed in the water column were presumably related to the potential ease with which microbes obtained protein-derived materials and energy, the protein hydrolysable fraction being estimated at

  9. Carbon dioxide and the 'greenhouse effect': an unresolved problem

    Energy Technology Data Exchange (ETDEWEB)

    Smith, I

    1978-01-01

    This executive review evaluates current scientific literature concerned with the accumulation of carbon dioxide in the atmosphere. The extent and possible causes of natural variations in global climate are outlined as a background to potential variations due to human activity. Estimates are given on relative contributions of carbon dioxide to the atmosphere due to fossil fuel combustion, deforestation and other land modifications. The possibility of a rise in global temperature as a result of increasing the amount of carbon dioxide in the atmosphere is dicusssed including model predictions, natural factors which could compensate for or emphasize a warming effect, and the implications if extensive warming actually occurred. Carbon dioxide disposal is discussed, but there appears to be no practicable long-term means of accomplishing this. It is concluded that there is no evidence of a rise in global temperature due to carbon dioxide at present. Predictions, which involve a high degree of uncertainty, indicate that the global temperature could rise appreciably in the next century. An increase in precipitation rate is also expected. If these changes result in a redistribution of climatic zones, there may be problems in adapting agricultural belts in some regions. Complete melting of all the ice sheets would take several millenia. A partial melting of continental ice sheets would not necessarily occur in view of the increase in precipitation rates, but if it did, there would be a rise in sea level of a few metres. Melting of the Arctic sea ice would affect climate, but not sea level.

  10. Deposition of carbon dioxide

    International Nuclear Information System (INIS)

    2001-01-01

    In Norway, there is currently a debate about whether or not to build gas power stations. To meet the possibility of reduced emission quotas for carbon dioxide in the future, current interest focuses on the incorporation of large-scale separation and deposition of carbon dioxide when such plants are planned. A group of experts concludes that this technology will become self-financing by means of environmental taxes. From the environmental point of view, taxes upon production are to be preferred over taxes on consumption

  11. Climate Change in Myanmar: Impacts and Adaptation

    Science.gov (United States)

    2014-12-01

    Intelligence Agency CO2 carbon dioxide CO2e carbon dioxide equivalent EIA environmental impact assessment ENSO El Nino southern oscillation EPA...therefore exposed to long-term climatic impacts such 25 Central Intelligence Agency [CIA], “The World...economy as well as result in human suffering through increased rates of malnutrition , health problems, and mortality. The IPCC and the global

  12. Adaptability and climate change

    International Nuclear Information System (INIS)

    Sprague, M.W.

    1991-01-01

    The potential social, economic and environmental impacts of climate change are reviewed, with emphasis on agricultural implications. Impact analyses must be done on the scale of watersheds or river basins. For agriculture, climate change effects on water resources are likely to be more important than temperature changes, and climatic variability is also equally important. Another set of critical climatic variables are the frequencies, magnitudes and timing of extreme events such as floods, droughts, etc. A carbon dioxide enriched atmosphere will increase water use efficiency and confer increased tolerance to drought, salinity and air pollution. Better understanding and accounting is required for the effects of increased carbon dioxide on all plant life, including crops. Adaptability of agriculture to change must be taken into account in predicting impacts of climate change, with technological innovation and infrastructure giving agriculture a dynamic nature. Limitations and adaptations must be considered when formulating public policy, to ensure that marginal costs do not exceed marginal benefits. Monoculture plantation forests may be the most efficient sinks of atmospheric carbon dioxide, yet widespread reliance on them may harm biological diversity. Actions the U.S. is currently taking under a no-regrets policy are summarized

  13. Persistence of climate changes due to a range of greenhouse gases.

    Science.gov (United States)

    Solomon, Susan; Daniel, John S; Sanford, Todd J; Murphy, Daniel M; Plattner, Gian-Kasper; Knutti, Reto; Friedlingstein, Pierre

    2010-10-26

    Emissions of a broad range of greenhouse gases of varying lifetimes contribute to global climate change. Carbon dioxide displays exceptional persistence that renders its warming nearly irreversible for more than 1,000 y. Here we show that the warming due to non-CO(2) greenhouse gases, although not irreversible, persists notably longer than the anthropogenic changes in the greenhouse gas concentrations themselves. We explore why the persistence of warming depends not just on the decay of a given greenhouse gas concentration but also on climate system behavior, particularly the timescales of heat transfer linked to the ocean. For carbon dioxide and methane, nonlinear optical absorption effects also play a smaller but significant role in prolonging the warming. In effect, dampening factors that slow temperature increase during periods of increasing concentration also slow the loss of energy from the Earth's climate system if radiative forcing is reduced. Approaches to climate change mitigation options through reduction of greenhouse gas or aerosol emissions therefore should not be expected to decrease climate change impacts as rapidly as the gas or aerosol lifetime, even for short-lived species; such actions can have their greatest effect if undertaken soon enough to avoid transfer of heat to the deep ocean.

  14. Measurements of carbon dioxide and heat fluxes during monsoon ...

    Indian Academy of Sciences (India)

    An increase in carbon dioxide (CO2) concentrations in the atmosphere due to ... The changes in land ... the air quality and climate models. 2. ... soon period of 2011 as a part Cloud Aerosol .... density effects due to heat and water vapour trans-.

  15. 2001-2002 carbon dioxide emissions in OECD

    International Nuclear Information System (INIS)

    2004-11-01

    This document provides carbon dioxide emissions data, from energy uses and production, from 2001 to 2002 in the OECD. It concerns the climate corrected CO 2 emissions in France, the non corrected CO 2 emissions (M tons), the emissions intensity / the Gross Domestic Product and the emissions intensity / the population (tons per inhabitant). (A.L.B.)

  16. Electrochemical carbon dioxide reduction on rough copper surfaces

    NARCIS (Netherlands)

    Kas, Recep

    2016-01-01

    Sustainable development and climate change is considered to be one of the top challenges of humanity. Electrochemical carbon dioxide (CO2) reduction to fuels or fuel precursor using renewable electricity is a very promising way to recycle CO2 and store the electricity. This would also provide

  17. Direct weakening of tropical circulations from masked CO2 radiative forcing.

    Science.gov (United States)

    Merlis, Timothy M

    2015-10-27

    Climate models robustly simulate weakened mean circulations of the tropical atmosphere in direct response to increased carbon dioxide (CO2). The direct response to CO2, defined by the response to radiative forcing in the absence of changes in sea surface temperature, affects tropical precipitation and tropical cyclone genesis, and these changes have been tied to the weakening of the mean tropical circulation. The mechanism underlying this direct CO2-forced circulation change has not been elucidated. Here, I demonstrate that this circulation weakening results from spatial structure in CO2's radiative forcing. In regions of ascending circulation, such as the intertropical convergence zone, the CO2 radiative forcing is reduced, or "masked," by deep-convective clouds and high humidity; in subsiding regions, such as the subtropics, the CO2 radiative forcing is larger because the atmosphere is drier and deep-convective clouds are infrequent. The spatial structure of the radiative forcing reduces the need for the atmosphere to transport energy. This, in turn, weakens the mass overturning of the tropical circulation. The previously unidentified mechanism is demonstrated in a hierarchy of atmospheric general circulation model simulations with altered radiative transfer to suppress the cloud masking of the radiative forcing. The mechanism depends on the climatological distribution of clouds and humidity, rather than uncertain changes in these quantities. Masked radiative forcing thereby offers an explanation for the robustness of the direct circulation weakening under increased CO2.

  18. Global Climate Change: Three Policy Perspectives

    National Research Council Canada - National Science Library

    Parker, Larry; Blodgett, John

    2008-01-01

    The 1992 U.N. Framework Convention on Climate Change requires that signatories, including the United States, establish policies for constraining future emission levels of greenhouse gases, including carbon dioxide (CO2). The George H. W...

  19. Climate change science - beyond IPCC

    International Nuclear Information System (INIS)

    Nicholls, N.

    2007-01-01

    Full text: Full text: The main conclusions of the IPCC Working Group I assessment of the physical science of climate change, from the Fourth IPCC Assessment, will be presented, along with the evidence supporting these conclusions. These conclusions include: Global atmospheric concentrations of carbon dioxide, methane and nitrous oxide have increased markedly as a result of human activities since 1750 and now far exceed pre-industrial values determined from ice cores spanning many thousands of years. The global increases in carbon dioxide concentration are due primarily to fossil fuel use and land use change, while those of methane and nitrous oxide are primarily due to agriculture; The understanding of anthropogenic warming and cooling influences on climate has improved since the Third Assessment Report, leading to very high confidence that the global average net effect of human activities since 1750 has been one of warming, with a radiative forcing of +1.6 [+0.6 to +2.4] Wm-2; Warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global average sea level; At continental, regional and ocean basin scales, numerous long-term changes in climate have been observed. These include changes in arctic temperatures and ice, widespread changes in precipitation amounts, ocean salinity, wind patterns and aspects of extreme weather including droughts, heavy precipitation, heat waves and the intensity of tropical cyclones. Palaeo-climatic information supports the interpretation that the warmth of the last half-century is unusual in at least the previous 1,300 years; Most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations; Discernible human influences now extend to other aspects of climate, including ocean warming, continental

  20. The Effects of Discrimination on Job Satisfaction in the Military: Comparing Evidence from the Armed Forces Equal Opportunity Survey and the Military Equal Opportunity Climate Survey

    National Research Council Canada - National Science Library

    Stewart, James

    2001-01-01

    ...) are analyzed separately. Comparison of the two analyses confirms positive relations among racial/ethnic groups or, more generally, a healthy climate for equal opportunity is associated with higher levels of satisfaction...

  1. Vegetation dynamics and its driving forces from climate change and human activities in the Three-River Source Region, China from 1982 to 2012

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Ying; Zhang, Chaobin; Wang, Zhaoqi; Chen, Yizhao; Gang, Chengcheng [School of Life Science, Nanjing University, Xianlin Road 163, Qixia District, Nanjing, 210046 (China); An, Ru [School of Earth Science and Engineering, Hohai University, Xikang Road 129, Nanjing, 210098 (China); Li, Jianlong, E-mail: lijianlongnju@163.com [School of Life Science, Nanjing University, Xianlin Road 163, Qixia District, Nanjing, 210046 (China)

    2016-09-01

    The Three-River Source Region (TRSR), a region with key importance to the ecological security of China, has undergone climate changes and a shift in human activities driven by a series of ecological restoration projects in recent decades. To reveal the spatiotemporal dynamics of vegetation dynamics and calculate the contributions of driving factors in the TRSR across different periods from 1982 to 2012, net primary productivity (NPP) estimated using the Carnegie–Ames–Stanford approach model was used to assess the status of vegetation. The actual effects of different climatic variation trends on interannual variation in NPP were analyzed. Furthermore, the relationships of NPP with different climate factors and human activities were analyzed quantitatively. Results showed the following: from 1982 to 2012, the average NPP in the study area was 187.37 g cm{sup −2} yr{sup −1}. The average NPP exhibited a fluctuation but presented a generally increasing trend over the 31-year study period, with an increase rate of 1.31 g cm{sup −2} yr{sup −2}. During the entire study period, the average contributions of temperature, precipitation, and solar radiation to NPP interannual variation over the entire region were 0.58, 0.73, and 0.09 g cm{sup −2} yr{sup −2}, respectively. Radiation was the climate factor with the greatest influence on NPP interannual variation. The factor that restricted NPP increase changed from temperature and radiation to precipitation. The average contributions of climate change and human activities to NPP interannual variation were 1.40 g cm{sup −2} yr{sup −2} and − 0.08 g cm{sup −2} yr{sup −2}, respectively. From 1982 to 2000, the general climate conditions were favorable to vegetation recovery, whereas human activities had a weaker negative impact on vegetation growth. From 2001 to 2012, climate conditions began to have a negative impact on vegetation growth, whereas human activities made a favorable impact on vegetation

  2. Vegetation dynamics and its driving forces from climate change and human activities in the Three-River Source Region, China from 1982 to 2012

    International Nuclear Information System (INIS)

    Zhang, Ying; Zhang, Chaobin; Wang, Zhaoqi; Chen, Yizhao; Gang, Chengcheng; An, Ru; Li, Jianlong

    2016-01-01

    The Three-River Source Region (TRSR), a region with key importance to the ecological security of China, has undergone climate changes and a shift in human activities driven by a series of ecological restoration projects in recent decades. To reveal the spatiotemporal dynamics of vegetation dynamics and calculate the contributions of driving factors in the TRSR across different periods from 1982 to 2012, net primary productivity (NPP) estimated using the Carnegie–Ames–Stanford approach model was used to assess the status of vegetation. The actual effects of different climatic variation trends on interannual variation in NPP were analyzed. Furthermore, the relationships of NPP with different climate factors and human activities were analyzed quantitatively. Results showed the following: from 1982 to 2012, the average NPP in the study area was 187.37 g cm"−"2 yr"−"1. The average NPP exhibited a fluctuation but presented a generally increasing trend over the 31-year study period, with an increase rate of 1.31 g cm"−"2 yr"−"2. During the entire study period, the average contributions of temperature, precipitation, and solar radiation to NPP interannual variation over the entire region were 0.58, 0.73, and 0.09 g cm"−"2 yr"−"2, respectively. Radiation was the climate factor with the greatest influence on NPP interannual variation. The factor that restricted NPP increase changed from temperature and radiation to precipitation. The average contributions of climate change and human activities to NPP interannual variation were 1.40 g cm"−"2 yr"−"2 and − 0.08 g cm"−"2 yr"−"2, respectively. From 1982 to 2000, the general climate conditions were favorable to vegetation recovery, whereas human activities had a weaker negative impact on vegetation growth. From 2001 to 2012, climate conditions began to have a negative impact on vegetation growth, whereas human activities made a favorable impact on vegetation recovery. - Highlights: • Partitioned the

  3. Carbon Dioxide Sensor Technology.

    Science.gov (United States)

    1983-04-01

    second gas permeable membrane separates a compartment containing the non-aqueous " solvent dimethylsulfoxide , ( DMSO ), from the aqueous solution...compartment. In DMSO carbon dioxide can be irreversibly reduced electrochemically to * non-interfering products...current due to its reduction in the DMSO solution is proportional to the partial pressure of CO2 in the gas phase. Overall, the linear response and

  4. Carbon dioxide sensor

    Science.gov (United States)

    Dutta, Prabir K [Worthington, OH; Lee, Inhee [Columbus, OH; Akbar, Sheikh A [Hilliard, OH

    2011-11-15

    The present invention generally relates to carbon dioxide (CO.sub.2) sensors. In one embodiment, the present invention relates to a carbon dioxide (CO.sub.2) sensor that incorporates lithium phosphate (Li.sub.3PO.sub.4) as an electrolyte and sensing electrode comprising a combination of lithium carbonate (Li.sub.2CO.sub.3) and barium carbonate (BaCO.sub.3). In another embodiment, the present invention relates to a carbon dioxide (CO.sub.2) sensor has a reduced sensitivity to humidity due to a sensing electrode with a layered structure of lithium carbonate and barium carbonate. In still another embodiment, the present invention relates to a method of producing carbon dioxide (CO.sub.2) sensors having lithium phosphate (Li.sub.3PO.sub.4) as an electrolyte and sensing electrode comprising a combination of lithium carbonate (Li.sub.2CO.sub.3) and barium carbonate (BaCO.sub.3).

  5. Are the impacts of land use on warming underestimated in climate policy?

    Science.gov (United States)

    Mahowald, Natalie M.; Ward, Daniel S.; Doney, Scott C.; Hess, Peter G.; Randerson, James T.

    2017-09-01

    While carbon dioxide emissions from energy use must be the primary target of climate change mitigation efforts, land use and land cover change (LULCC) also represent an important source of climate forcing. In this study we compute time series of global surface temperature change separately for LULCC and non-LULCC sources (primarily fossil fuel burning), and show that because of the extra warming associated with the co-emission of methane and nitrous oxide with LULCC carbon dioxide emissions, and a co-emission of cooling aerosols with non-LULCC emissions of carbon dioxide, the linear relationship between cumulative carbon dioxide emissions and temperature has a two-fold higher slope for LULCC than for non-LULCC activities. Moreover, projections used in the Intergovernmental Panel on Climate Change (IPCC) for the rate of tropical land conversion in the future are relatively low compared to contemporary observations, suggesting that the future projections of land conversion used in the IPCC may underestimate potential impacts of LULCC. By including a ‘business as usual’ future LULCC scenario for tropical deforestation, we find that even if all non-LULCC emissions are switched off in 2015, it is likely that 1.5 °C of warming relative to the preindustrial era will occur by 2100. Thus, policies to reduce LULCC emissions must remain a high priority if we are to achieve the low to medium temperature change targets proposed as a part of the Paris Agreement. Future studies using integrated assessment models and other climate simulations should include more realistic deforestation rates and the integration of policy that would reduce LULCC emissions.

  6. DOE Final Report on Collaborative Research. Quantifying Climate Feedbacks of the Terrestrial Biosphere under Thawing Permafrost Conditions in the Arctic

    Energy Technology Data Exchange (ETDEWEB)

    Zhuang, Qianlai [Purdue Univ., West Lafayette, IN (United States); Schlosser, C. Adam [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Melillo, Jerry M. [Marine Biological Lab. (MBL), Woods Hole, MA (United States); Anthony, Katey Walter [Univ. of Alaska, Fairbanks, AK (United States); Kicklighter, David [Marine Biological Lab. (MBL), Woods Hole, MA (United States); Gao, Xiang [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

    2015-11-03

    Our overall goal is to quantify the potential for threshold changes in natural emission rates of trace gases, particularly methane and carbon dioxide, from pan-arctic terrestrial systems under the spectrum of anthropogenically-forced climate warming, and the conditions under which these emissions provide a strong feedback mechanism to global climate warming. This goal is motivated under the premise that polar amplification of global climate warming will induce widespread thaw and degradation of the permafrost, and would thus cause substantial changes to the landscape of wetlands and lakes, especially thermokarst (thaw) lakes, across the Arctic. Through a suite of numerical experiments that encapsulate the fundamental processes governing methane emissions and carbon exchanges – as well as their coupling to the global climate system - we intend to test the following hypothesis in the proposed research: There exists a climate warming threshold beyond which permafrost degradation becomes widespread and stimulates large increases in methane emissions (via thermokarst lakes and poorly-drained wetland areas upon thawing permafrost along with microbial metabolic responses to higher temperatures) and increases in carbon dioxide emissions from well-drained areas. Besides changes in biogeochemistry, this threshold will also influence global energy dynamics through effects on surface albedo, evapotranspiration and water vapor. These changes would outweigh any increased uptake of carbon (e.g. from peatlands and higher plant photosynthesis) and would result in a strong, positive feedback to global climate warming.

  7. Climate change and climate policy

    International Nuclear Information System (INIS)

    Alfsen, Knut H.; Kolshus, Hans H.; Torvanger, Asbjoern

    2000-08-01

    The climate issue is a great political and scientific challenge for several reasons: (1) There are many uncertain aspects of the climate problem, such as future emission of climate gases, the response of the climate system upon these gases, and the effects of climate changes. (2) It is probable, however, that anthropogenic emission of climate gases, deforestation etc. will cause noticeable climate changes in the future. This might be observed as increased frequency of extreme weather situations. This appears to be a greater threat than a gradual increase of temperature and precipitation. (3) Since the climate system is large and react only relatively slowly on changes in for instance the emission of climate gases, the climate problem can only be solved by means of long-term measures. (4) The climate changes may be irreversible. A rational short-term strategy is to ensure maximum flexibility, which can be done by ''slowing down'' (curtailing emissions) and by avoiding irreversible actions as much as possible. The long-term challenge is to develop an economically responsible alternative to the present fossil-based energy system that permits carbon-efficient technologies to compete on price with coal and unconventional oil and gas. Norway is in a special position by being a large exporter of fossil fuel and at the same time wanting to appear responsible in environmental matters. This combination may incur considerable expenses upon Norway and it is therefore important that environmental commitments like the Kyoto agreement can be honoured to the lowest possible cost. The costs can be minimized by: (1) minimizing the measure costs in Norway, (2) working to make the international quota price as low as possible, and (3) reducing the loss of petroleum income as much as possible. This report describes the earth's climate history, the forces behind climatic changes and what the prospects for the future look like. It also reviews what is being done to curtail the emission of

  8. Nuclear energy significantly reduces carbon dioxide emissions

    International Nuclear Information System (INIS)

    Koprda, V.

    2006-01-01

    This article is devoted to nuclear energy, to its acceptability, compatibility and sustainability. Nuclear energy is non-dispensable part of energy sources with vast innovation potential. The safety of nuclear energy, radioactive waste deposition, and prevention of risk from misuse of nuclear material have to be very seriously adjudged and solved. Nuclear energy is one of the ways how to decrease the contamination of atmosphere with carbon dioxide and it solves partially also the problem of global increase of temperature and climate changes. Given are the main factors responsible for the renaissance of nuclear energy. (author)

  9. The carbon dioxide capture and geological storage

    International Nuclear Information System (INIS)

    2006-06-01

    This road-map proposes by the Group Total aims to inform the public on the carbon dioxide capture and geological storage. One possible means of climate change mitigation consists of storing the CO 2 generated by the greenhouse gases emission in order to stabilize atmospheric concentrations. This sheet presents the CO 2 capture from lage fossil-fueled combustion installations, the three capture techniques and the CO 2 transport options, the geological storage of the CO 2 and Total commitments in the domain. (A.L.B.)

  10. Impacts of climate change on range expansion by the mountain pine beetle

    Energy Technology Data Exchange (ETDEWEB)

    Carroll, A.L.; Taylor, S.W. [Canadian Forest Service, Victoria, BC (Canada). Pacific Forestry Centre; Regniere, J. [Canadian Forest Service, Quebec, PQ (Canada). Laurentian Forestry Centre; Logan, J.A.; Bentz, B.J. [United States Dept. of Agriculture, Logan, UT (United States). Logan Forestry Sciences Laboratory; Powell, J.A. [Utah State Univ., Logan, UT (United States). Dept. of Mathematics and Statistics

    2006-07-01

    The elevational and latitudinal range of mountain pine beetle (MPB) has been limited by climatic conditions that are currently unfavorable for brood development. This study examined the impact of climatic conditions on the establishment and persistence of MPB using a spatially explicit, climate-driven simulation tool. Historic weather records were also used to create maps of past habitats for MPB in British Columbia. Map overlays were then created to determine if MPB has expanded its range due to changes in the province's climate. The distribution of climatically suitable habitats was examined in 10-year increments. Results of the study showed an increase in benign habitats. MPB populations have expanded into new areas as a result of changes in climate. Additional range expansion for MPB was then assessed using a global circulation model along with a conservative forcing scenario that forecast a doubling of carbon dioxide (CO{sub 2}) by 2050. Weather conditions were then combined with a climatic suitability model in order to examine areas of climatically suitable habitats. It was concluded that continued eastward expansion by MPB is probable. 44 refs., 4 tabs., 7 figs.

  11. Carbon dioxide dangers demonstration model

    Science.gov (United States)

    Venezky, Dina; Wessells, Stephen

    2010-01-01

    Carbon dioxide is a dangerous volcanic gas. When carbon dioxide seeps from the ground, it normally mixes with the air and dissipates rapidly. However, because carbon dioxide gas is heavier than air, it can collect in snowbanks, depressions, and poorly ventilated enclosures posing a potential danger to people and other living things. In this experiment we show how carbon dioxide gas displaces oxygen as it collects in low-lying areas. When carbon dioxide, created by mixing vinegar and baking soda, is added to a bowl with candles of different heights, the flames are extinguished as if by magic.

  12. Regional and Global Climate Response to Anthropogenic SO2 Emissions from China in Three Climate Models

    Science.gov (United States)

    Kasoar, M.; Voulgarakis, Apostolos; Lamarque, Jean-Francois; Shindell, Drew T.; Bellouin, Nicholas; Collins, William J.; Faluvegi, Greg; Tsigaridis, Kostas

    2016-01-01

    We use the HadGEM3-GA4, CESM1, and GISS ModelE2 climate models to investigate the global and regional aerosol burden, radiative flux, and surface temperature responses to removing anthropogenic sulfur dioxide (SO2) emissions from China. We find that the models differ by up to a factor of 6 in the simulated change in aerosol optical depth (AOD) and shortwave radiative flux over China that results from reduced sulfate aerosol, leading to a large range of magnitudes in the regional and global temperature responses. Two of the three models simulate a near-ubiquitous hemispheric warming due to the regional SO2 removal, with similarities in the local and remote pattern of response, but overall with a substantially different magnitude. The third model simulates almost no significant temperature response. We attribute the discrepancies in the response to a combination of substantial differences in the chemical conversion of SO2 to sulfate, translation of sulfate mass into AOD, cloud radiative interactions, and differences in the radiative forcing efficiency of sulfate aerosol in the models. The model with the strongest response (HadGEM3-GA4) compares best with observations of AOD regionally, however the other two models compare similarly (albeit poorly) and still disagree substantially in their simulated climate response, indicating that total AOD observations are far from sufficient to determine which model response is more plausible. Our results highlight that there remains a large uncertainty in the representation of both aerosol chemistry as well as direct and indirect aerosol radiative effects in current climate models, and reinforces that caution must be applied when interpreting the results of modelling studies of aerosol influences on climate. Model studies that implicate aerosols in climate responses should ideally explore a range of radiative forcing strengths representative of this uncertainty, in addition to thoroughly evaluating the models used against

  13. Role of Atmospheric Chemistry in the Climate Impacts of Stratospheric Volcanic Injections

    Science.gov (United States)

    Legrande, Allegra N.; Tsigaridis, Kostas; Bauer, Susanne E.

    2016-01-01

    The climate impact of a volcanic eruption is known to be dependent on the size, location and timing of the eruption. However, the chemistry and composition of the volcanic plume also control its impact on climate. It is not just sulfur dioxide gas, but also the coincident emissions of water, halogens and ash that influence the radiative and climate forcing of an eruption. Improvements in the capability of models to capture aerosol microphysics, and the inclusion of chemistry and aerosol microphysics modules in Earth system models, allow us to evaluate the interaction of composition and chemistry within volcanic plumes in a new way. These modeling efforts also illustrate the role of water vapor in controlling the chemical evolution, and hence climate impacts, of the plume. A growing realization of the importance of the chemical composition of volcanic plumes is leading to a more sophisticated and realistic representation of volcanic forcing in climate simulations, which in turn aids in reconciling simulations and proxy reconstructions of the climate impacts of past volcanic eruptions. More sophisticated simulations are expected to help, eventually, with predictions of the impact on the Earth system of any future large volcanic eruptions.

  14. The Ideological Divide Concerning Climate Change Opinion: Integrating Top-Down and Bottom-Up Approaches

    Directory of Open Access Journals (Sweden)

    Jennifer eJacquet

    2014-12-01

    Full Text Available The United States wields disproportionate global influence in terms of carbon dioxide emissions and international climate policy. This renders it an especially important context in which to examine the interplay among social, psychological, and political factors in shaping attitudes and behaviors about climate change. In this article, we review the emerging literature addressing the liberal-conservative divide in the U.S. with respect to thought, communication, and action concerning climate change. Because of its theoretical and practical significance, we focus on the motivational basis for skepticism and inaction on the part of some, including top-down institutional forces, such as corporate strategy, and bottom-up psychological factors, such as ego, group, and system justification. Although more research is needed to elucidate fully the social, cognitive, and motivational bases of environmental attitudes and behavior, a great deal has been learned in just a few years by focusing on specific ideological factors in addition to general psychological principles.

  15. Climate change

    International Nuclear Information System (INIS)

    1998-01-01

    The indicators in this bulletin are part of a national set of environmental indicators designed to provide a profile of the state of Canada's environment and measure progress towards sustainable development. A review of potential impacts on Canada shows that such changes would have wide-ranging implications for its economic sectors, social well-being including human health, and ecological systems. This document looks at the natural state of greenhouse gases which help regulate the Earth's climate. Then it looks at human influence and what is being done about it. The document then examines some indicators: Carbon dioxide emissions from fossil fuel use; global atmospheric concentrations of greenhouse gases; and global and Canadian temperature variations

  16. Assessing the metrics of climate change. Current methods and future possibilities

    Energy Technology Data Exchange (ETDEWEB)

    Fuglestveit, Jan S.; Berntsen, Terje K.; Godal, Odd; Sausen, Robert; Shine, Keith P.; Skodvin, Tora

    2001-07-01

    With the principle of comprehensiveness embedded in the UN Framework Convention on Climate Change (Art. 3), a multi-gas abatement strategy with emphasis also on non-CO2 greenhouse gases as targets for reduction and control measures has been adopted in the international climate regime. In the Kyoto Protocol, the comprehensive approach is made operative as the aggregate anthropogenic carbon dioxide equivalent emissions of six specified greenhouse gases or groups of gases (Art. 3). With this operationalisation, the emissions of a set of greenhouse gases with very different atmospheric lifetimes and radiative properties are transformed into one common unit - CO2 equivalents. This transformation is based on the Global Warming Potential (GWP) index, which in turn is based on the concept of radiative forcing. The GWP metric and its application in policy making has been debated, and several other alternative concepts have been suggested. In this paper, we review existing and alternative metrics of climate change, with particular emphasis on radiative forcing and GWPs, in terms of their scientific performance. This assessment focuses on questions such as the climate impact (end point) against which gases are weighted; the extent to which and how temporality is included, both with regard to emission control and with regard to climate impact; how cost issues are dealt with; and the sensitivity of the metrics to various assumptions. It is concluded that the radiative forcing concept is a robust and useful metric of the potential climatic impact of various agents and that there are prospects for improvement by weighing different forcings according to their effectiveness. We also find that although the GWP concept is associated with serious shortcomings, it retains advantages over any of the proposed alternatives in terms of political feasibility. Alternative metrics, however, make a significant contribution to addressing important issues, and this contribution should be taken

  17. Assessing the metrics of climate change. Current methods and future possibilities

    International Nuclear Information System (INIS)

    Fuglestveit, Jan S.; Berntsen, Terje K.; Godal, Odd; Sausen, Robert; Shine, Keith P.; Skodvin, Tora

    2001-01-01

    With the principle of comprehensiveness embedded in the UN Framework Convention on Climate Change (Art. 3), a multi-gas abatement strategy with emphasis also on non-CO2 greenhouse gases as targets for reduction and control measures has been adopted in the international climate regime. In the Kyoto Protocol, the comprehensive approach is made operative as the aggregate anthropogenic carbon dioxide equivalent emissions of six specified greenhouse gases or groups of gases (Art. 3). With this operationalisation, the emissions of a set of greenhouse gases with very different atmospheric lifetimes and radiative properties are transformed into one common unit - CO2 equivalents. This transformation is based on the Global Warming Potential (GWP) index, which in turn is based on the concept of radiative forcing. The GWP metric and its application in policy making has been debated, and several other alternative concepts have been suggested. In this paper, we review existing and alternative metrics of climate change, with particular emphasis on radiative forcing and GWPs, in terms of their scientific performance. This assessment focuses on questions such as the climate impact (end point) against which gases are weighted; the extent to which and how temporality is included, both with regard to emission control and with regard to climate impact; how cost issues are dealt with; and the sensitivity of the metrics to various assumptions. It is concluded that the radiative forcing concept is a robust and useful metric of the potential climatic impact of various agents and that there are prospects for improvement by weighing different forcings according to their effectiveness. We also find that although the GWP concept is associated with serious shortcomings, it retains advantages over any of the proposed alternatives in terms of political feasibility. Alternative metrics, however, make a significant contribution to addressing important issues, and this contribution should be taken

  18. Incorporating changes in albedo in estimating the climate mitigation benefits of land use change projects

    Science.gov (United States)

    Bird, D. N.; Kunda, M.; Mayer, A.; Schlamadinger, B.; Canella, L.; Johnston, M.

    2008-04-01

    Some climate scientists are questioning whether the practice of converting of non-forest lands to forest land (afforestation or reforestation) is an effective climate change mitigation option. The discussion focuses particularly on areas where the new forest is primarily coniferous and there is significant amount of snow since the increased climate forcing due to the change in albedo may counteract the decreased climate forcing due to carbon dioxide removal. In this paper, we develop a stand-based model that combines changes in surface albedo, solar radiation, latitude, cloud cover and carbon sequestration. As well, we develop a procedure to convert carbon stock changes to equivalent climatic forcing or climatic forcing to equivalent carbon stock changes. Using the model, we investigate the sensitivity of combined affects of changes in surface albedo and carbon stock changes to model parameters. The model is sensitive to amount of cloud, atmospheric absorption, timing of canopy closure, carbon sequestration rate among other factors. The sensitivity of the model is investigated at one Canadian site, and then the model is tested at numerous sites across Canada. In general, we find that the change in albedo reduces the carbon sequestration benefits by approximately 30% over 100 years, but this is not drastic enough to suggest that one should not use afforestation or reforestation as a climate change mitigation option. This occurs because the forests grow in places where there is significant amount of cloud in winter. As well, variations in sequestration rate seem to be counterbalanced by the amount and timing of canopy closure. We close by speculating that the effects of albedo may also be significant in locations at lower latitudes, where there are less clouds, and where there are extended dry seasons. These conditions make grasses light coloured and when irrigated crops, dark forests or other vegetation such as biofuels replace the grasses, the change in carbon

  19. Modification of pure oxygen absorption equipment for concurrent stripping of carbon dioxide

    Science.gov (United States)

    Watten, B.J.; Sibrell, P.L.; Montgomery, G.A.; Tsukuda, S.M.

    2004-01-01

    The high solubility of carbon dioxide precludes significant desorption within commercial oxygen absorption equipment. This operating characteristic of the equipment limits its application in recirculating water culture systems despite its ability to significantly increase allowable fish loading rates (kg/(L min)). Carbon dioxide (DC) is typically removed by air stripping. This process requires a significant energy input for forced air movement, air heating in cold climates and water pumping. We developed a modification for a spray tower that provides for carbon dioxide desorption as well as oxygen absorption. Elimination of the air-stripping step reduces pumping costs while allowing dissolved nitrogen to drop below saturation concentrations. This latter response provides for an improvement in oxygen absorption efficiency within the spray tower. DC desorption is achieved by directing head-space gases from the spray tower (O2, N2, CO2) through a sealed packed tower scrubber receiving a 2 N NaOH solution. Carbon dioxide is selectively removed from the gas stream, by chemical reaction, forming the product Na 2CO3. Scrubber off-gas, lean with regard to carbon dioxide but still rich with oxygen, is redirected through the spray tower for further stripping of DC and absorption of oxygen. Make-up NaOH is metered into the scrubbing solution sump on an as needed basis as directed by a feedback control loop programmed to maintain a scrubbing solution pH of 11.4-11.8. The spent NaOH solution is collected, then regenerated for reuse, in a batch process that requires relatively inexpensive hydrated lime (Ca(OH)2). A by-product of the regeneration step is an alkaline filter cake, which may have use in bio-solids stabilization. Given the enhanced gas transfer rates possible with chemical reaction, the required NaOH solution flow rate through the scrubber represents a fraction of the spray tower water flow rate. Further, isolation of the water being treated from the atmosphere (1

  20. Targets for Global Climate Policy: An Overview

    OpenAIRE

    Richard S.J. Tol

    2012-01-01

    A survey of the economic impact of climate change and the marginal damage costs shows that carbon dioxide emissions are a negative externality. The estimated Pigou tax and its growth rate are too low to justify the climate policy targets set by political leaders. A lower discount rate or greater concern for the global distribution of income would justify more stringent climate policy, but would imply an overhaul of other public policy. Catastrophic risk justifies more stringent climate policy...

  1. Decadal vegetation changes in a northern peatland, greenhouse gas fluxes and net radiative forcing

    DEFF Research Database (Denmark)

    Johansson, Torbjörn; Malmer, Nils; Crill, Patrick M

    2006-01-01

    SUB-ARCTIC MIRE; CLIMATE-CHANGE; BOREAL PEATLANDS; METHANE EMISSIONS; VASCULAR PLANTS; CARBON-DIOXIDE; PERMAFROST THAW; CO2 EXCHANGE; WATER-TABLE......SUB-ARCTIC MIRE; CLIMATE-CHANGE; BOREAL PEATLANDS; METHANE EMISSIONS; VASCULAR PLANTS; CARBON-DIOXIDE; PERMAFROST THAW; CO2 EXCHANGE; WATER-TABLE...

  2. Methanation of Carbon Dioxide

    OpenAIRE

    Goodman, Daniel Jacob

    2013-01-01

    The emission of greenhouse gases into the atmosphere has been linked to global warming. Carbon dioxide's (CO2) one of the most abundant greenhouse gases. Natural gas, mainly methane, is the cleanest fossil fuel for electricity production helping meet the United States ever growing energy needs. The methanation of CO2 has the potential to address both of these problems if a catalyst can be developed that meets the activity, economic and environmental requirements to industrialize the process. ...

  3. CARBON DIOXIDE FIXATION.

    Energy Technology Data Exchange (ETDEWEB)

    FUJITA,E.

    2000-01-12

    Solar carbon dioxide fixation offers the possibility of a renewable source of chemicals and fuels in the future. Its realization rests on future advances in the efficiency of solar energy collection and development of suitable catalysts for CO{sub 2} conversion. Recent achievements in the efficiency of solar energy conversion and in catalysis suggest that this approach holds a great deal of promise for contributing to future needs for fuels and chemicals.

  4. Production of uranium dioxide

    International Nuclear Information System (INIS)

    Hart, J.E.; Shuck, D.L.; Lyon, W.L.

    1977-01-01

    A continuous, four stage fluidized bed process for converting uranium hexafluoride (UF 6 ) to ceramic-grade uranium dioxide (UO 2 ) powder suitable for use in the manufacture of fuel pellets for nuclear reactors is disclosed. The process comprises the steps of first reacting UF 6 with steam in a first fluidized bed, preferably at about 550 0 C, to form solid intermediate reaction products UO 2 F 2 , U 3 O 8 and an off-gas including hydrogen fluoride (HF). The solid intermediate reaction products are conveyed to a second fluidized bed reactor at which the mol fraction of HF is controlled at low levels in order to prevent the formation of uranium tetrafluoride (UF 4 ). The first intermediate reaction products are reacted in the second fluidized bed with steam and hydrogen at a temperature of about 630 0 C. The second intermediate reaction product including uranium dioxide (UO 2 ) is conveyed to a third fluidized bed reactor and reacted with additional steam and hydrogen at a temperature of about 650 0 C producing a reaction product consisting essentially of uranium dioxide having an oxygen-uranium ratio of about 2 and a low residual fluoride content. This product is then conveyed to a fourth fluidized bed wherein a mixture of air and preheated nitrogen is introduced in order to further reduce the fluoride content of the UO 2 and increase the oxygen-uranium ratio to about 2.25

  5. Future discharge drought across climate regions around the world modelled with a synthetic hydrological modelling approach forced by three general circulation models

    NARCIS (Netherlands)

    Wanders, N.; Van Lanen, H. A J

    2015-01-01

    Hydrological drought characteristics (drought in groundwater and streamflow) likely will change in the 21st century as a result of climate change. The magnitude and directionality of these changes and their dependency on climatology and catchment characteristics, however, is uncertain. In this study

  6. Airborne DOAS retrievals of methane, carbon dioxide, and water vapor concentrations at high spatial resolution: application to AVIRIS-NG

    Directory of Open Access Journals (Sweden)

    A. K. Thorpe

    2017-10-01

    Full Text Available At local scales, emissions of methane and carbon dioxide are highly uncertain. Localized sources of both trace gases can create strong local gradients in its columnar abundance, which can be discerned using absorption spectroscopy at high spatial resolution. In a previous study, more than 250 methane plumes were observed in the San Juan Basin near Four Corners during April 2015 using the next-generation Airborne Visible/Infrared Imaging Spectrometer (AVIRIS-NG and a linearized matched filter. For the first time, we apply the iterative maximum a posteriori differential optical absorption spectroscopy (IMAP-DOAS method to AVIRIS-NG data and generate gas concentration maps for methane, carbon dioxide, and water vapor plumes. This demonstrates a comprehensive greenhouse gas monitoring capability that targets methane and carbon dioxide, the two dominant anthropogenic climate-forcing agents. Water vapor results indicate the ability of these retrievals to distinguish between methane and water vapor despite spectral interference in the shortwave infrared. We focus on selected cases from anthropogenic and natural sources, including emissions from mine ventilation shafts, a gas processing plant, tank, pipeline leak, and natural seep. In addition, carbon dioxide emissions were mapped from the flue-gas stacks of two coal-fired power plants and a water vapor plume was observed from the combined sources of cooling towers and cooling ponds. Observed plumes were consistent with known and suspected emission sources verified by the true color AVIRIS-NG scenes and higher-resolution Google Earth imagery. Real-time detection and geolocation of methane plumes by AVIRIS-NG provided unambiguous identification of individual emission source locations and communication to a ground team for rapid follow-up. This permitted verification of a number of methane emission sources using a thermal camera, including a tank and buried natural gas pipeline.

  7. Airborne DOAS retrievals of methane, carbon dioxide, and water vapor concentrations at high spatial resolution: application to AVIRIS-NG

    Science.gov (United States)

    Thorpe, Andrew K.; Frankenberg, Christian; Thompson, David R.; Duren, Riley M.; Aubrey, Andrew D.; Bue, Brian D.; Green, Robert O.; Gerilowski, Konstantin; Krings, Thomas; Borchardt, Jakob; Kort, Eric A.; Sweeney, Colm; Conley, Stephen; Roberts, Dar A.; Dennison, Philip E.

    2017-10-01

    At local scales, emissions of methane and carbon dioxide are highly uncertain. Localized sources of both trace gases can create strong local gradients in its columnar abundance, which can be discerned using absorption spectroscopy at high spatial resolution. In a previous study, more than 250 methane plumes were observed in the San Juan Basin near Four Corners during April 2015 using the next-generation Airborne Visible/Infrared Imaging Spectrometer (AVIRIS-NG) and a linearized matched filter. For the first time, we apply the iterative maximum a posteriori differential optical absorption spectroscopy (IMAP-DOAS) method to AVIRIS-NG data and generate gas concentration maps for methane, carbon dioxide, and water vapor plumes. This demonstrates a comprehensive greenhouse gas monitoring capability that targets methane and carbon dioxide, the two dominant anthropogenic climate-forcing agents. Water vapor results indicate the ability of these retrievals to distinguish between methane and water vapor despite spectral interference in the shortwave infrared. We focus on selected cases from anthropogenic and natural sources, including emissions from mine ventilation shafts, a gas processing plant, tank, pipeline leak, and natural seep. In addition, carbon dioxide emissions were mapped from the flue-gas stacks of two coal-fired power plants and a water vapor plume was observed from the combined sources of cooling towers and cooling ponds. Observed plumes were consistent with known and suspected emission sources verified by the true color AVIRIS-NG scenes and higher-resolution Google Earth imagery. Real-time detection and geolocation of methane plumes by AVIRIS-NG provided unambiguous identification of individual emission source locations and communication to a ground team for rapid follow-up. This permitted verification of a number of methane emission sources using a thermal camera, including a tank and buried natural gas pipeline.

  8. Thermal Oxidation of Structured Silicon Dioxide

    DEFF Research Database (Denmark)

    Christiansen, Thomas Lehrmann; Hansen, Ole; Jensen, Jørgen Arendt

    2014-01-01

    The topography of thermally oxidized, structured silicon dioxide is investigated through simulations, atomic force microscopy, and a proposed analytical model. A 357 nm thick oxide is structured by removing regions of the oxide in a masked etch with either reactive ion etching or hydrofluoric acid....... Subsequent thermal oxidation is performed in both dry and wet ambients in the temperature range 950◦C to 1100◦C growing a 205 ± 12 nm thick oxide in the etched mask windows. Lifting of the original oxide near the edge of the mask in the range 6 nm to 37 nm is seen with increased lifting for increasing...

  9. Record annual increase of carbon dioxide observed at Mauna Loa for 2015 |

    Science.gov (United States)

    Climate Oceans & Coasts Fisheries Satellites Research Marine & Aviation Charting Sanctuaries Research Record annual increase of carbon dioxide observed at Mauna Loa for 2015 Climate Research Share Niño weather pattern, as forests, plantlife and other terrestrial systems responded to changes in

  10. Bounding the Role of Black Carbon in the Climate System: a Scientific Assessment

    Science.gov (United States)

    Bond, T. C.; Doherty, S. J.; Fahey, D. W.; Forster, P. M.; Bernsten, T.; DeAngelo, B. J.; Flanner, M. G.; Ghan, S.; Karcher, B.; Koch, D.; hide

    2013-01-01

    and warm the climate. We estimate that black carbon, with a total climate forcing of +1.1 W/sq m, is the second most important human emission in terms of its climate forcing in the present-day atmosphere; only carbon dioxide is estimated to have a greater forcing. Sources that emit black carbon also emit other short-lived species that may either cool or warm climate. Climate forcings from co-emitted species are estimated and used in the framework described herein. When the principal effects of short-lived co-emissions, including cooling agents such as sulfur dioxide, are included in net forcing, energy-related sources (fossil fuel and biofuel) have an industrial-era climate forcing of +0.22 (0.50 to +1.08) W/sq m during the first year after emission. For a few of these sources, such as diesel engines and possibly residential biofuels, warming is strong enough that eliminating all short-lived emissions from these sources would reduce net climate forcing (i.e., produce cooling). When open burning emissions, which emit high levels of organic matter, are included in the total, the best estimate of net industrial-era climate forcing by all short-lived species from black-carbon-rich sources becomes slightly negative (0.06 W/sq m with 90% uncertainty bounds of 1.45 to +1.29 W/sq m). The uncertainties in net climate forcing from black-carbon-rich sources are substantial, largely due to lack of knowledge about cloud interactions with both black carbon and co-emitted organic carbon. In prioritizing potential black-carbon mitigation actions, non-science factors, such as technical feasibility, costs, policy design, and implementation feasibility play important roles. The major sources of black carbon are presently in different stages with regard to the feasibility for near-term mitigation. This assessment, by evaluating the large number and complexity of the associated physical and radiative processes in black-carbon climate forcing, sets a baseline from which to improve future

  11. Greenhouse effect and climate

    International Nuclear Information System (INIS)

    Flohn, H.

    1987-01-01

    Model calculations with different marginal conditions and different physical processes do, on the basis of realistic assumptions, result in a temperature rise of 3 ± 1.5degC at doubling carbon dioxide concentrations. Temperatures are increasing even more due to the presence of trace gases contributing to the greenhouse effect. They are assumed to be having a share of 100% in the carbon dioxide effect (additive) in 30-40 years from now. According to the model calculations the CO 2 increase from about 280 ppm around 1850 to 345 ppm (1985) is equal to a globally averaged temperature rise of 0.5-0.7degC. As the data obtained before 1900 were incomplete and little representative climatic analyses cannot be considered to have been effective but after that time. However, considering the additional influence of other climatic effects such as vulcanism the temperature rise satisfactorily corresponds to the values obtained since 1900. (orig./HP) [de

  12. Molybdenum dioxide-molybdenite roasting

    International Nuclear Information System (INIS)

    Sabacky, B.J.; Hepworth, M.T.

    1984-01-01

    A process is disclosed for roasting molybdenite concentrates directly to molybdenum dioxide. The process comprises establishing a roasting zone having a temperature of about 700 0 C. to about 800 0 C., introducing into the roasting zone particulate molybdenum dioxide and molybdenite in a weight ratio of at least about 2:1 along with an oxygen-containing gas in amount sufficient to oxidize the sulfur content of the molybdenite to molybdenum dioxide

  13. Evaluating the Contribution of Climate Forcing and Forest Dynamics to Accelerating Carbon Sequestration by Forest Ecosystems in the Northeastern U.S.: Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Munger, J. William [Harvard University, SEAS; Foster, David R. [Harvard University, Harvard Forest; Richardson, Andrew D. [Harvard University, OEB

    2014-10-01

    This report summarizes work to improve quantitative understanding of the terrestrial ecosystem processes that control carbon sequestration in unmanaged forests It builds upon the comprehensive long-term observations of CO2 fluxes, climate and forest structure and function at the Harvard Forest in Petersham, MA. This record includes the longest CO2 flux time series in the world. The site is a keystone for the AmeriFlux network. Project Description The project synthesizes observations made at the Harvard Forest HFEMS and Hemlock towers, which represent the dominant mixed deciduous and coniferous forest types in the northeastern United States. The 20+ year record of carbon uptake at Harvard Forest and the associated comprehensive meteorological and biometric data, comprise one of the best data sets to challenge ecosystem models on time scales spanning hourly, daily, monthly, interannual and multi-decadal intervals, as needed to understand ecosystem change and climate feedbacks.

  14. Regional hydrological impacts of climate change: implications for water management in India

    Directory of Open Access Journals (Sweden)

    A. Mondal

    2015-04-01

    Full Text Available Climate change is most likely to introduce an additional stress to already stressed water systems in developing countries. Climate change is inherently linked with the hydrological cycle and is expected to cause significant alterations in regional water resources systems necessitating measures for adaptation and mitigation. Increasing temperatures, for example, are likely to change precipitation patterns resulting in alterations of regional water availability, evapotranspirative water demand of crops and vegetation, extremes of floods and droughts, and water quality. A comprehensive assessment of regional hydrological impacts of climate change is thus necessary. Global climate model simulations provide future projections of the climate system taking into consideration changes in external forcings, such as atmospheric carbon-dioxide and aerosols, especially those resulting from anthropogenic emissions. However, such simulations are typically run at a coarse scale, and are not equipped to reproduce regional hydrological processes. This paper summarizes recent research on the assessment of climate change impacts on regional hydrology, addressing the scale and physical processes mismatch issues. Particular attention is given to changes in water availability, irrigation demands and water quality. This paper also includes description of the methodologies developed to address uncertainties in the projections resulting from incomplete knowledge about future evolution of the human-induced emissions and from using multiple climate models. Approaches for investigating possible causes of historically observed changes in regional hydrological variables are also discussed. Illustrations of all the above-mentioned methods are provided for Indian regions with a view to specifically aiding water management in India.

  15. Interannual Variability of Carbon Dioxide, Methane and Nitrous Oxide Fluxes in Subarctic European Russian Tundra

    Science.gov (United States)

    Marushchak, M. E.; Voigt, C.; Gil, J.; Lamprecht, R. E.; Trubnikova, T.; Virtanen, T.; Kaverin, D.; Martikainen, P. J.; Biasi, C.

    2017-12-01

    Southern tundra landscapes are particularly vulnerable to climate warming, permafrost thaw and associated landscape rearrangement due to near-zero permafrost temperatures. The large soil C and N stocks of subarctic tundra may create a positive feedback for warming if released to the atmosphere at increased rates. Subarctic tundra in European Russia is a mosaic of land cover types, which all play different roles in the regional greenhouse gas budget. Peat plateaus - massive upheaved permafrost peatlands - are large storehouses of soil carbon and nitrogen, but include also bare peat surfaces that act as hot-spots for both carbon dioxide and nitrous oxide emissions. Tundra wetlands are important for the regional greenhouse gas balance since they show high rates of methane emissions and carbon uptake. The most dominant land-form is upland tundra vegetated by shrubs, lichens and mosses, which displays a close-to-neutral balance with respect to all three greenhouse gases. The study site Seida (67°03'N, 62°56'E), located in the discontinuous permafrost zone of Northeast European Russia, incorporates all these land forms and has been an object for greenhouse gas investigations since 2007. Here, we summarize the growing season fluxes of carbon dioxide, methane and nitrous oxide measured by chamber techniques over the study years. We analyzed the flux time-series together with the local environmental data in order to understand the drivers of interannual variability. Detailed soil profile measurements of greenhouse gas concentrations, soil moisture and temperature provide insights into soil processes underlying the net emissions to the atmosphere. The multiannual time-series allows us to assess the importance of the different greenhouse gases and landforms to the overall climate forcing of the study region.

  16. Subatomic forces

    International Nuclear Information System (INIS)

    Sutton, C.

    1989-01-01

    Inside the atom, particles interact through two forces which are never felt in the everyday world. But they may hold the key to the Universe. These ideas on subatomic forces are discussed with respect to the strong force, the electromagnetic force and the electroweak force. (author)

  17. Climate saver atomic energy?

    International Nuclear Information System (INIS)

    1992-12-01

    According to the Schleswig-Holstein Land government nuclear power phaseout is compatible with measures designed to protect world climate. Only efforts aimed at quickly reducing energy demand by means of thermal insulation, energy conservation techniques, cogeneration systems and application of renewable energies are necessary. The Schleswig-Holstein energy concept is given as an example of making possible a worldwide carbon dioxide reduction. (DG) [de

  18. Lessons on climate sensitivity from past climate changes

    NARCIS (Netherlands)

    von der Heydt, A.S.; Dijkstra, H.A.; van de Wal, R.S.W.; Caballero, R.; Crucifix, M.; Foster, G.L.; Huber, M.; Kohler, P.; Rohling, E.; Valdes, P.J.; Ashwin, P.; Bathiany, S.; Berends, T.; van Bree, L.G.J.; Ditlevsen, P.; Ghil, M.; Haywood, A.; Katzav, J.K.; Lohmann, G.; Lohmann, J.; Lucarini, V.; Marzocchi, A.; Palike, H.; Ruvalcaba Baroni, I.; Simon, D.; Sluijs, A.; Stap, L.B.; Tantet, A.; Viebahn, J.; Ziegler, M.

    2016-01-01

    Over the last decade, our understanding of climate sensitivity has improved considerably. The climate system shows variability on many timescales, is subject to non-stationary forcing and it is most likely out of equilibrium with the changes in the radiative forcing. Slow and fast feedbacks

  19. The carbon dioxide problem - a challenge to environmental protection

    International Nuclear Information System (INIS)

    Hlubek, W.; Spalthoff, F.J.

    1989-01-01

    Over the last century, man's activities on earth have sent off trace gases into the planet's atmosphere that have been concentrating to a level posing a threat to the global climate. Since scientists particularly spotted carbon dioxide as the main contributor to what we now call the greenhouse effect, there is urgent need for measures reducing carbon dioxide emission worldwide, may be on the basis of a global convention to be signed by both the industrialised and the developing countries. The industrialised countries, which certainly are the main pollutors, also will have the technological and financial resources to respond to the challenge of global warning more directly and faster than the developing countries. The power industry's management in the FRG is taking the problem seriously and has already come out with strategies for curbing carbon dioxide emissions from fossil-fuel power plant. (orig.) [de

  20. Influence of roughness on capillary forces between hydrophilic surfaces

    NARCIS (Netherlands)

    van Zwol, P. J.; Palasantzas, G.; De Hosson, J. Th. M.

    Capillary forces have been measured by atomic force microscopy in the plate-sphere setup between gold, borosilicate glass, GeSbTe, titanium, and UV-irradiated amorphous titanium-dioxide surfaces. The force measurements were performed as a function contact time and surface roughness in the range

  1. Process for sequestering carbon dioxide and sulfur dioxide

    Science.gov (United States)

    Maroto-Valer, M Mercedes [State College, PA; Zhang, Yinzhi [State College, PA; Kuchta, Matthew E [State College, PA; Andresen, John M [State College, PA; Fauth, Dan J [Pittsburgh, PA

    2009-10-20

    A process for sequestering carbon dioxide, which includes reacting a silicate based material with an acid to form a suspension, and combining the suspension with carbon dioxide to create active carbonation of the silicate-based material, and thereafter producing a metal salt, silica and regenerating the acid in the liquid phase of the suspension.

  2. Western forests, fire risk, and climate change.

    Science.gov (United States)

    Valerie. Rapp

    2004-01-01

    Climate warming may first show up in forests as increased growth, which occurs as warmer temperatures, increased carbon dioxide, and more precipitation encourage higher rates of photosynthesis. The second way that climate change may show up in forests is through changes in disturbance regimes—the long-term patterns of fire, drought, insects, and diseases that are basic...

  3. Western forest, fire risk, and climate change

    Science.gov (United States)

    Valerie Rapp

    2004-01-01

    Climate warming may first show up in forests as increased growth, which occurs as warmer temperatures, increased carbon dioxide, and more precipitation encourage higher rates of photosynthesis. The second way that climate change may show up in forests is through changes in disturbance regimes—the long-term patterns of fire, drought, insects, and diseases that are basic...

  4. Targets for global climate policy : An overview

    NARCIS (Netherlands)

    Tol, Richard S.J.

    A survey of the economic impact of climate change and the marginal damage costs shows that carbon dioxide emissions are a negative externality. The estimated Pigou tax and its growth rate are too low to justify the climate policy targets set by political leaders. A lower discount rate or greater

  5. Intensification of Chile-Peru upwelling under climate change: diagnosing the impact of natural and anthropogenic forcing from the IPSL-CM5 model.

    Science.gov (United States)

    Jebri, B.; Khodri, M.; Gastineau, G.; Echevin, V.; Thiria, S.

    2017-12-01

    Upwelling is critical to the biological production, acidification, and deoxygenation of the ocean's major eastern boundary current ecosystems. A conceptual hypothesis suggests that the winds that favour coastal upwelling intensify with anthropogenic global warming due to increased land-sea temperature contrast. We examine this hypothesis for the dynamics of the Peru-Chile upwelling using a set of four large ensembles of coupled, ocean-atmosphere model simulations with the IPSL model covering the 1940-2014 period. In one large ensemble we prescribe the standard CMIP5 greenhouse gas (GHG) concentrations, anthropogenic aerosol, ozone and volcanic forcings, following the historical experiments through 2005 and RCP8.5 from 2006-2014, while the other ensembles consider separately the GHG, ozone and volcanic forcings. We find evidence for intensification of upwelling-favourable winds with however little evidence of atmospheric pressure gradients in response to increasing land-sea temperature differences. Our analyses reveal poleward migration and intensification of the South Pacific Anticyclone near poleward boundaries of climatological Peruvian and Chilean upwelling zones. This contribution further investigates the physical mechanisms for the Peru-Chile upwelling intensification and the relative role of natural and anthropogenic forcings.

  6. Transport impacts on atmosphere and climate: Shipping

    Science.gov (United States)

    Eyring, Veronika; Isaksen, Ivar S. A.; Berntsen, Terje; Collins, William J.; Corbett, James J.; Endresen, Oyvind; Grainger, Roy G.; Moldanova, Jana; Schlager, Hans; Stevenson, David S.

    2010-12-01

    Emissions of exhaust gases and particles from oceangoing ships are a significant and growing contributor to the total emissions from the transportation sector. We present an assessment of the contribution of gaseous and particulate emissions from oceangoing shipping to anthropogenic emissions and air quality. We also assess the degradation in human health and climate change created by these emissions. Regulating ship emissions requires comprehensive knowledge of current fuel consumption and emissions, understanding of their impact on atmospheric composition and climate, and projections of potential future evolutions and mitigation options. Nearly 70% of ship emissions occur within 400 km of coastlines, causing air quality problems through the formation of ground-level ozone, sulphur emissions and particulate matter in coastal areas and harbours with heavy traffic. Furthermore, ozone and aerosol precursor emissions as well as their derivative species from ships may be transported in the atmosphere over several hundreds of kilometres, and thus contribute to air quality problems further inland, even though they are emitted at sea. In addition, ship emissions impact climate. Recent studies indicate that the cooling due to altered clouds far outweighs the warming effects from greenhouse gases such as carbon dioxide (CO 2) or ozone from shipping, overall causing a negative present-day radiative forcing (RF). Current efforts to reduce sulphur and other pollutants from shipping may modify this. However, given the short residence time of sulphate compared to CO 2, the climate response from sulphate is of the order decades while that of CO 2 is centuries. The climatic trade-off between positive and negative radiative forcing is still a topic of scientific research, but from what is currently known, a simple cancellation of global mean forcing components is potentially inappropriate and a more comprehensive assessment metric is required. The CO 2 equivalent emissions using

  7. Limited impact on decadal-scale climate change from increased use of natural gas.

    Science.gov (United States)

    McJeon, Haewon; Edmonds, Jae; Bauer, Nico; Clarke, Leon; Fisher, Brian; Flannery, Brian P; Hilaire, Jérôme; Krey, Volker; Marangoni, Giacomo; Mi, Raymond; Riahi, Keywan; Rogner, Holger; Tavoni, Massimo

    2014-10-23

    The most important energy development of the past decade has been the wide deployment of hydraulic fracturing technologies that enable the production of previously uneconomic shale gas resources in North America. If these advanced gas production technologies were to be deployed globally, the energy market could see a large influx of economically competitive unconventional gas resources. The climate implications of such abundant natural gas have been hotly debated. Some researchers have observed that abundant natural gas substituting for coal could reduce carbon dioxide (CO2) emissions. Others have reported that the non-CO2 greenhouse gas emissions associated with shale gas production make its lifecycle emissions higher than those of coal. Assessment of the full impact of abundant gas on climate change requires an integrated approach to the global energy-economy-climate systems, but the literature has been limited in either its geographic scope or its coverage of greenhouse gases. Here we show that market-driven increases in global supplies of unconventional natural gas do not discernibly reduce the trajectory of greenhouse gas emissions or climate forcing. Our results, based on simulations from five state-of-the-art integrated assessment models of energy-economy-climate systems independently forced by an abundant gas scenario, project large additional natural gas consumption of up to +170 per cent by 2050. The impact on CO2 emissions, however, is found to be much smaller (from -2 per cent to +11 per cent), and a majority of the models reported a small increase in climate forcing (from -0.3 per cent to +7 per cent) associated with the increased use of abundant gas. Our results show that although market penetration of globally abundant gas may substantially change the future energy system, it is not necessarily an effective substitute for climate change mitigation policy.

  8. Changes of Air Pollution and Climate Forcing Emissions due to Fuel Switching to Gasohol in Motorcycle Fleet in an Urban Area of Thailand

    Directory of Open Access Journals (Sweden)

    Rattapon Onchang

    2017-07-01

    Full Text Available This research aims to examine the exhaust emission changed due to fuel switching to gasohol in actual motorcycles (MC fleet in Nakhon Pathom municipality, Thailand. International Vehicle Emissions (IVE model was applied by specifying the year 2010 as a base case and the target year of 2020 as Business as Usual (BAU. The parking lot survey, GPS monitoring and MC counting on selected roads during weekday and weekend were conducted. Fuel switching from gasoline octane number 91 to gasohol in all MC fleet in the municipality was set as a scenario according to current Thailand’s transport energy policies. Total pollution emissions reduction of the following pollutants after switching to gasohol E10 (10% of ethanol for all MC in the fleet compared to BAU were obtained: benzene (86%, 1,3-butadiene (69%, VOC (including evaporation (31% and CO (29%, while the following pollutants increased: acetaldehydes (>100%, formaldehydes (51%, NOx (9% and PM (5%. Gasohol use scenario produced larger amount of CO2 (29% and CH4 (9%. Only a small deviation of climate forcer emissions in CO2-equivalent (reduced by 8% for 20-year and increased by 2% for 100-year horizon were obtained. Switching to gasohol in MC fleet in Nakhon Pathom municipality unable to achieve air quality and climate co-benefit. Restriction of the local emission factors (EFs available for adjusting the model’s EFs can be influence to the emission calculation. Also, as PM was excluded from the calculation of GWP due to lack of OC and EC information, this can affect the analysis of climate forcer emissions.

  9. Long-term growth-increment chronologies reveal diverse influences of climate forcing on freshwater and forest biota in the Pacific Northwest.

    Science.gov (United States)

    Black, Bryan A; Dunham, Jason B; Blundon, Brett W; Brim-Box, Jayne; Tepley, Alan J

    2015-02-01

    Analyses of how organisms are likely to respond to a changing climate have focused largely on the direct effects of warming temperatures, though changes in other variables may also be important, particularly the amount and timing of precipitation. Here, we develop a network of eight growth-increment width chronologies for freshwater mussel species in the Pacific Northwest, United States and integrate them with tree-ring data to evaluate how terrestrial and aquatic indicators respond to hydroclimatic variability, including river discharge and precipitation. Annual discharge averaged across water years (October 1-September 30) was highly synchronous among river systems and imparted a coherent pattern among mussel chronologies. The leading principal component of the five longest mussel chronologies (1982-2003; PC1(mussel)) accounted for 47% of the dataset variability and negatively correlated with the leading principal component of river discharge (PC1(discharge); r = -0.88; P < 0.0001). PC1(mussel) and PC1(discharge) were closely linked to regional wintertime precipitation patterns across the Pacific Northwest, the season in which the vast majority of annual precipitation arrives. Mussel growth was also indirectly related to tree radial growth, though the nature of the relationships varied across the landscape. Negative correlations occurred in forests where tree growth tends to be limited by drought while positive correlations occurred in forests where tree growth tends to be limited by deep or lingering snowpack. Overall, this diverse assemblage of chronologies illustrates the importance of winter precipitation to terrestrial and freshwater ecosystems and suggests that a complexity of climate responses must be considered when estimating the biological impacts of climate variability and change. © 2014 John Wiley & Sons Ltd.

  10. Report of the workshop on Climate Sensitivity

    International Nuclear Information System (INIS)

    2004-01-01

    The IPCC Working Group I (WGI) held this Workshop on Climate Sensitivity as a major keystone in activities preparing for the WGI contribution to the IPCC Fourth Assessment Report (AR4). One of the most important parameters in climate science is the 'climate sensitivity', broadly defined as the global mean temperature change for a given forcing, often that of a doubling of atmospheric carbon dioxide. Climate sensitivity has played a central role throughout the history of IPCC in interpretation of model outputs, in evaluation of future climate changes expected from various scenarios, and it is closely linked to attribution of currently observed climate changes. An ongoing challenge to models and to climate projections has been to better define this key parameter, and to understand the differences in computed values between various models. Throughout the last three IPCC assessments the climate sensitivity has been estimated as being in the range 1.5 to 4.5 deg. C for CO 2 doubling (i.e., uncertain by a factor of three), making this parameter central to discussions of uncertainty in climate change. The aims of the workshop were to: - Evaluate a range of climate model results so as to relate different climate sensitivity estimates to differences descriptions of physical processes, particularly those related to atmospheric water vapor, clouds, lapse rate changes, ocean heat uptake, treatment of evapotranspiration, land-atmosphere coupling, etc.; - Obtain a more comprehensive picture of the relationships between climate sensitivity and other model features such as resolution, numerical approach, radiative transfer parameters, etc.; - Consider how current, historical, and paleo-climatic data can aid in the determination of the likely range of climate sensitivity; - Improve the understanding of the interpretation and limits of the climate sensitivity concept, including for example possible dependencies upon different forcing agents, predictability questions, and transient

  11. Report of the workshop on Climate Sensitivity

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2004-07-01

    The IPCC Working Group I (WGI) held this Workshop on Climate Sensitivity as a major keystone in activities preparing for the WGI contribution to the IPCC Fourth Assessment Report (AR4). One of the most important parameters in climate science is the 'climate sensitivity', broadly defined as the global mean temperature change for a given forcing, often that of a doubling of atmospheric carbon dioxide. Climate sensitivity has played a central role throughout the history of IPCC in interpretation of model outputs, in evaluation of future climate changes expected from various scenarios, and it is closely linked to attribution of currently observed climate changes. An ongoing challenge to models and to climate projections has been to better define this key parameter, and to understand the differences in computed values between various models. Throughout the last three IPCC assessments the climate sensitivity has been estimated as being in the range 1.5 to 4.5 deg. C for CO{sub 2} doubling (i.e., uncertain by a factor of three), making this parameter central to discussions of uncertainty in climate change. The aims of the workshop were to: - Evaluate a range of climate model results so as to relate different climate sensitivity estimates to differences descriptions of physical processes, particularly those related to atmospheric water vapor, clouds, lapse rate changes, ocean heat uptake, treatment of evapotranspiration, land-atmosphere coupling, etc.; - Obtain a more comprehensive picture of the relationships between climate sensitivity and other model features such as resolution, numerical approach, radiative transfer parameters, etc.; - Consider how current, historical, and paleo-climatic data can aid in the determination of the likely range of climate sensitivity; - Improve the understanding of the interpretation and limits of the climate sensitivity concept, including for example possible dependencies upon different forcing agents, predictability questions

  12. Report of the workshop on Climate Sensitivity

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2004-07-01

    The IPCC Working Group I (WGI) held this Workshop on Climate Sensitivity as a major keystone in activities preparing for the WGI contribution to the IPCC Fourth Assessment Report (AR4). One of the most important parameters in climate science is the 'climate sensitivity', broadly defined as the global mean temperature change for a given forcing, often that of a doubling of atmospheric carbon dioxide. Climate sensitivity has played a central role throughout the history of IPCC in interpretation of model outputs, in evaluation of future climate changes expected from various scenarios, and it is closely linked to attribution of currently observed climate changes. An ongoing challenge to models and to climate projections has been to better define this key parameter, and to understand the differences in computed values between various models. Throughout the last three IPCC assessments the climate sensitivity has been estimated as being in the range 1.5 to 4.5 deg. C for CO{sub 2} doubling (i.e., uncertain by a factor of three), making this parameter central to discussions of uncertainty in climate change. The aims of the workshop were to: - Evaluate a range of climate model results so as to relate different climate sensitivity estimates to differences descriptions of physical processes, particularly those related to atmospheric water vapor, clouds, lapse rate changes, ocean heat uptake, treatment of evapotranspiration, land-atmosphere coupling, etc.; - Obtain a more comprehensive picture of the relationships between climate sensitivity and other model features such as resolution, numerical approach, radiative transfer parameters, etc.; - Consider how current, historical, and paleo-climatic data can aid in the determination of the likely range of climate sensitivity; - Improve the understanding of the interpretation and limits of the climate sensitivity concept, including for example possible dependencies upon different forcing agents, predictability questions, and

  13. Public Perceptions of How Long Air Pollution and Carbon Dioxide Remain in the Atmosphere.

    Science.gov (United States)

    Dryden, Rachel; Morgan, M Granger; Bostrom, Ann; Bruine de Bruin, Wändi

    2018-03-01

    The atmospheric residence time of carbon dioxide is hundreds of years, many orders of magnitude longer than that of common air pollution, which is typically hours to a few days. However, randomly selected respondents in a mail survey in Allegheny County, PA (N = 119) and in a national survey conducted with MTurk (N = 1,013) judged the two to be identical (in decades), considerably overestimating the residence time of air pollution and drastically underestimating that of carbon dioxide. Moreover, while many respondents believed that action is needed today to avoid climate change (regardless of cause), roughly a quarter held the view that if climate change is real and serious, we will be able to stop it in the future when it happens, just as we did with common air pollution. In addition to assessing respondents' understanding of how long carbon dioxide and common air pollution stay in the atmosphere, we also explored the extent to which people correctly identified causes of climate change and how their beliefs affect support for action. With climate change at the forefront of politics and mainstream media, informing discussions of policy is increasingly important. Confusion about the causes and consequences of climate change, and especially about carbon dioxide's long atmospheric residence time, could have profound implications for sustained support of policies to achieve reductions in carbon dioxide emissions and other greenhouse gases. © 2017 Society for Risk Analysis.

  14. Contrasting regional versus global radiative forcing by megacity pollution emissions

    Science.gov (United States)

    Dang, H.; Unger, N.

    2015-10-01

    We assess the regional and global integrated radiative forcing on 20- and 100-year time horizons caused by a one-year pulse of present day pollution emissions from 10 megacity areas: Los Angeles, Mexico City, New York City, Sao Paulo, Lagos, Cairo, New Delhi, Beijing, Shanghai and Manila. The assessment includes well-mixed greenhouse gases: carbon dioxide (CO2), nitrous oxide (N2O), methane (CH4); and short-lived climate forcers: tropospheric ozone (O3) and fine mode aerosol particles (sulfate, nitrate, black carbon, primary and secondary organic aerosol). All megacities contribute net global warming on both time horizons. Most of the 10 megacity areas exert a net negative effect on their own regional radiation budget that is 10-100 times larger in magnitude than their global radiative effects. Of the cities examined, Beijing, New Delhi, Shanghai and New York contribute most to global warming with values ranging from +0.03 to 0.05 Wm-2yr on short timescales and +0.07-0.10 Wm-2yr on long timescales. Regional net 20-year radiative effects are largest for Mexico City (-0.84 Wm-2yr) and Beijing (-0.78 Wm-2yr). Megacity reduction of non-CH4 O3 precursors to improve air quality offers zero co-benefits to global climate. Megacity reduction of aerosols to improve air quality offers co-benefits to the regional radiative budget but minimal or no co-benefits to global climate with the exception of black carbon reductions in a few cities, especially Beijing and New Delhi. Results suggest that air pollution and global climate change mitigation can be treated as separate environmental issues in policy at the megacity level with the exception of CH4 action. Individual megacity reduction of CO2 and CH4 emissions can mitigate global warming and therefore offers climate safety improvements to the entire planet.

  15. Phytoplankton and Climate

    Science.gov (United States)

    Moisan, John R.

    2009-01-01

    Ocean phytoplankton supply about half of the oxygen that humans utilize to sustain life. In this lecture, we will explore how phytoplankton plays a critical role in modulating the Earth's climate. These tiny organisms are the base of the Ocean's food web. They can modulate the rate at which solar heat is absorbed by the ocean, either through direct absorption or through production of highly scattering cellular coverings. They take up and help sequester carbon dioxide, a key greenhouse gas that modulated the Earth's climate. They are the source of cloud nucleation gases that are key to cloud formation/processes. They are also able to modify the nutrient budgets of the ocean through active uptake of inert atmospheric nitrogen. Climate variations have a pronounced impact on phytoplankton dynamics. Long term variations in the climate have been studied through geological interpretations on its influence on phytoplankton populations. The presentation will focus on presenting the numerous linkages that have been observed between climate and phytoplankton and further discuss how present climate change scenarios are likely to impact phytoplankton populations as well as present findings from several studies that have tried to understand how the climate might react to the feedbacks from these numerous climate-phytop|ankton linkages.

  16. The changing world of climate change: Oregon leads the states

    International Nuclear Information System (INIS)

    Carver, P.H.; Sadler, S.; Kosloff, L.H.; Trexler, M.C.

    1997-01-01

    Following on the heels of recent national and international developments in climate change policy, Oregon's open-quote best-of-batch close-quote proceeding has validated the use of CO 2 offsets as a cost-effective means of advancing climate change mitigation goals. The proceeding was a first in several respects and represents a record commitment of funds to CO 2 mitigation by a private entity. In December 1995, the Intergovernmental Panel on Climate Change (IPCC), issued its Second Assessment Report. The IPCC's conclusion that open-quotes[t]he balance of evidence suggests a discernible human influence on global climateclose quotes fundamentally changed the tenor of the policy debate regarding potential threats associated with global climate change. At the Climate Change Convention's Conference of the Parties (COP) in Geneva in July 1996, most countries, including the United States, advocated adopting the IPCC report as the basis for swift policy movement toward binding international emissions targets. The next COP, in December 1997, is scheduled to be the venue for the signing of a treaty protocol incorporating such targets. Binding targets would have major consequences for power plant operators in the US and around the world. Recent developments in the state of Oregon show the kinds of measures that may become commonplace at the state level in addressing climate change mitigation. First, Oregon recently completed the first administrative proceeding in the US aimed at offsetting the greenhouse gas emissions of a new power plant. Second, a legislatively mandated energy facility siting task force recently recommended that Oregon adopt a carbon dioxide (CO 2 ) standard for new power plant construction and drop use of the open-quotes need for powerclose quotes standard. This article reviews these two policy milestones and their implications for climate change mitigation in the United States

  17. Predator-induced reduction of freshwater carbon dioxide emissions

    Science.gov (United States)

    Atwood, Trisha B.; Hammill, Edd; Greig, Hamish S.; Kratina, Pavel; Shurin, Jonathan B.; Srivastava, Diane S.; Richardson, John S.

    2013-03-01

    Predators can influence the exchange of carbon dioxide between ecosystems and the atmosphere by altering ecosystem processes such as decomposition and primary production, according to food web theory. Empirical knowledge of such an effect in freshwater systems is limited, but it has been suggested that predators in odd-numbered food chains suppress freshwater carbon dioxide emissions, and predators in even-numbered food chains enhance emissions. Here, we report experiments in three-tier food chains in experimental ponds, streams and bromeliads in Canada and Costa Rica in the presence or absence of fish (Gasterosteus aculeatus) and invertebrate (Hesperoperla pacifica and Mecistogaster modesta) predators. We monitored carbon dioxide fluxes along with prey and primary producer biomass. We found substantially reduced carbon dioxide emissions in the presence of predators in all systems, despite differences in predator type, hydrology, climatic region, ecological zone and level of in situ primary production. We also observed lower amounts of prey biomass and higher amounts of algal and detrital biomass in the presence of predators. We conclude that predators have the potential to markedly influence carbon dioxide dynamics in freshwater systems.

  18. Carbon dioxide and the greenhouse effect: an unresolved problem

    Energy Technology Data Exchange (ETDEWEB)

    Smith, I M

    1978-01-01

    This paper evaluates current scientific literature concerned with the accumulation of carbon dioxide in the atmosphere. The extent and possible causes of natural variations in global climate are outlined as a background to potential variations due to human activity. Estimates are given on relative contributions of carbon dioxide to the atmosphere due to fossil fuel combustion, deforestation and other land modifications. The possibility of a rise in global temperature as a result of increasing the amount of carbon dioxide in the atmosphere is discussed including model predictions, natural factors which could compensate for or emphasize a warming effect, and the implications if extensive warming actually occurred. Carbon dioxide disposal is discussed but there appears to be no practicable long-term means of accomplishing this. It is concluded that there is no evidence of a rise in global temperature due to carbon dioxide at present. Predictions, which involve a high degree of uncertainty, indicate that the global temperature could rise appreciably in the next century. An increase in precipitation rate is also expected.

  19. Evaluating climatic response to external radiative forcing during the late Miocene to early Pliocene: New perspectives from eastern equatorial Pacific (IODP U1338) and North Atlantic (ODP 982) locations

    Science.gov (United States)

    Drury, Anna Joy; John, Cédric M.; Shevenell, Amelia E.

    2016-01-01

    Orbital-scale climate variability during the latest Miocene-early Pliocene is poorly understood due to a lack of high-resolution records spanning 8.0-3.5 Ma, which resolve all orbital cycles. Assessing this variability improves understanding of how Earth's system sensitivity to insolation evolves and provides insight into the factors driving the Messinian Salinity Crisis (MSC) and the Late Miocene Carbon Isotope Shift (LMCIS). New high-resolution benthic foraminiferal Cibicidoides mundulus δ18O and δ13C records from equatorial Pacific International Ocean Drilling Program Site U1338 are correlated to North Atlantic Ocean Drilling Program Site 982 to obtain a global perspective. Four long-term benthic δ18O variations are identified: the Tortonian-Messinian, Miocene-Pliocene, and Early-Pliocene Oxygen Isotope Lows (8-7, 5.9-4.9, and 4.8-3.5 Ma) and the Messinian Oxygen Isotope High (MOH; 7-5.9 Ma). Obliquity-paced variability dominates throughout, except during the MOH. Eleven new orbital-scale isotopic stages are identified between 7.4 and 7.1 Ma. Cryosphere and carbon cycle sensitivities, estimated from δ18O and δ13C variability, suggest a weak cryosphere-carbon cycle coupling. The MSC termination coincided with moderate cryosphere sensitivity and reduced global ice sheets. The LMCIS coincided with reduced carbon cycle sensitivity, suggesting a driving force independent of insolation changes. The response of the cryosphere and carbon cycle to obliquity forcing is established, defined as Earth System Response (ESR). Observations reveal that two late Miocene-early Pliocene climate states existed. The first is a prevailing dynamic state with moderate ESR and obliquity-driven Antarctic ice variations, associated with reduced global ice volumes. The second is a stable state, which occurred during the MOH, with reduced ESR and lower obliquity-driven variability, associated with expanded global ice volumes.

  20. Climate control of terrestrial carbon exchange across biomes and continents

    Science.gov (United States)

    Chuixiang Yi; Daniel Ricciuto; Runze Li; John Wolbeck; Xiyan Xu; Mats Nilsson; John Frank; William J. Massman

    2010-01-01

    Understanding the relationships between climate and carbon exchange by terrestrial ecosystems is critical to predict future levels of atmospheric carbon dioxide because of the potential accelerating effects of positive climate-carbon cycle feedbacks. However, directly observed relationships between climate and terrestrial CO2 exchange with the atmosphere across biomes...

  1. An analysis of the daily precipitation variability in the Himalayan orogen using a statistical parameterisation and its potential in driving landscape evolution models with stochastic climatic forcing

    Science.gov (United States)

    Deal, Eric; Braun, Jean

    2015-04-01

    A current challenge in landscape evolution modelling is to integrate realistic precipitation patterns and behaviour into longterm fluvial erosion models. The effect of precipitation on fluvial erosion can be subtle as well as nonlinear, implying that changes in climate (e.g. precipitation magnitude or storminess) may have unexpected outcomes in terms of erosion rates. For example Tucker and Bras (2000) show theoretically that changes in the variability of precipitation (storminess) alone can influence erosion rate across a landscape. To complicate the situation further, topography, ultimately driven by tectonic uplift but shaped by erosion, has a major influence on the distribution and style of precipitation. Therefore, in order to untangle the coupling between climate, erosion and tectonics in an actively uplifting orogen where fluvial erosion is dominant it is important to understand how the 'rain dial' used in a landscape evolution model (LEM) corresponds to real precipitation patterns. One issue with the parameterisation of rainfall for use in an LEM is the difference between the timescales for precipitation (≤ 1 year) and landscape evolution (> 103 years). As a result, precipitation patterns must be upscaled before being integrated into a model. The relevant question then becomes: What is the most appropriate measure of precipitation on a millennial timescale? Previous work (Tucker and Bras, 2000; Lague, 2005) has shown that precipitation can be properly upscaled by taking into account its variable nature, along with its average magnitude. This captures the relative size and frequency of extreme events, ensuring a more accurate characterisation of the integrated effects of precipitation on erosion over long periods of time. In light of this work, we present a statistical parameterisation that accurately models the mean and daily variability of ground based (APHRODITE) and remotely sensed (TRMM) precipitation data in the Himalayan orogen with only a few

  2. Cosmic Rays and Climate

    CERN Document Server

    Kirkby, Jasper

    2007-01-01

    Among the most puzzling questions in climate change is that of solar-climate variability, which has attracted the attention of scientists for more than two centuries. Until recently, even the existence of solar-climate variability has been controversial—perhaps because the observations had largely involved correlations between climate and the sunspot cycle that had persisted for only a few decades. Over the last few years, however, diverse reconstructions of past climate change have revealed clear associations with cosmic ray variations recorded in cosmogenic isotope archives, providing persuasive evidence for solar or cosmic ray forcing of the climate. However, despite the increasing evidence of its importance, solar-climate variability is likely to remain controversial until a physical mechanism is established. Although this remains a mystery, observations suggest that cloud cover may be influenced by cosmic rays, which are modulated by the solar wind and, on longer time scales, by the geomagnetic fiel...

  3. A continuous latitudinal energy balance model to explore non-uniform climate engineering strategies

    Science.gov (United States)

    Bonetti, F.; McInnes, C. R.

    2016-12-01

    Current concentrations of atmospheric CO2 exceed measured historical levels in modern times, largely attributed to anthropogenic forcing since the industrial revolution. The required decline in emissions rates has never been achieved leading to recent interest in climate engineering for future risk-mitigation strategies. Climate engineering aims to offset human-driven climate change. It involves techniques developed both to reduce the concentration of CO2 in the atmosphere (Carbon Dioxide Removal (CDR) methods) and to counteract the radiative forcing that it generates (Solar Radiation Management (SRM) methods). In order to investigate effects of SRM technologies for climate engineering, an analytical model describing the main dynamics of the Earth's climate has been developed. The model is a time-dependent Energy Balance Model (EBM) with latitudinal resolution and allows for the evaluation of non-uniform climate engineering strategies. A significant disadvantage of climate engineering techniques involving the management of solar radiation is regional disparities in cooling. This model offers an analytical approach to design multi-objective strategies that counteract climate change on a regional basis: for example, to cool the Artic and restrict undesired impacts at mid-latitudes, or to control the equator-to-pole temperature gradient. Using the Green's function approach the resulting partial differential equation allows for the computation of the surface temperature as a function of time and latitude when a 1% per year increase in the CO2 concentration is considered. After the validation of the model through comparisons with high fidelity numerical models, it will be used to explore strategies for the injection of the aerosol precursors in the stratosphere. In particular, the model involves detailed description of the optical properties of the particles, the wash-out dynamics and the estimation of the radiative cooling they can generate.

  4. 76 FR 56982 - Announcement of Federal Underground Injection Control (UIC) Class VI Program for Carbon Dioxide (CO2

    Science.gov (United States)

    2011-09-15

    ...-9465-1] Announcement of Federal Underground Injection Control (UIC) Class VI Program for Carbon Dioxide... Injection Control (UIC) Class VI Program for Carbon Dioxide (CO 2 ) Geologic Sequestration (GS) Wells under... highlighted in the ``Report of the Interagency Task Force on Carbon Capture and Storage'' (August 2010), it is...

  5. Climatic forcing and larval dispersal capabilities shape the replenishment of fishes and their habitat-forming biota on a tropical coral reef.

    Science.gov (United States)

    Wilson, Shaun K; Depcyznski, Martial; Fisher, Rebecca; Holmes, Thomas H; Noble, Mae M; Radford, Ben T; Rule, Michael; Shedrawi, George; Tinkler, Paul; Fulton, Christopher J

    2018-02-01

    Fluctuations in marine populations often relate to the supply of recruits by oceanic currents. Variation in these currents is typically driven by large-scale changes in climate, in particular ENSO (El Nino Southern Oscillation). The dependence on large-scale climatic changes may, however, be modified by early life history traits of marine taxa. Based on eight years of annual surveys, along 150 km of coastline, we examined how ENSO influenced abundance of juvenile fish, coral spat, and canopy-forming macroalgae. We then investigated what traits make populations of some fish families more reliant on the ENSO relationship than others. Abundance of juvenile fish and coral recruits was generally positively correlated with the Southern Oscillation Index (SOI), higher densities recorded during La Niña years, when the ENSO-influenced Leeuwin Current is stronger and sea surface temperature higher. The relationship is typically positive and stronger among fish families with shorter pelagic larval durations and stronger swimming abilities. The relationship is also stronger at sites on the coral back reef, although the strongest of all relationships were among the lethrinids ( r  = .9), siganids ( r  = .9), and mullids ( r  = .8), which recruit to macroalgal meadows in the lagoon. ENSO effects on habitat seem to moderate SOI-juvenile abundance relationship. Macroalgal canopies are higher during La Niña years, providing more favorable habitat for juvenile fish and strengthening the SOI effect on juvenile abundance. Conversely, loss of coral following a La Niña-related heat wave may have compromised postsettlement survival of coral dependent species, weakening the influence of SOI on their abundance. This assessment of ENSO effects on tropical fish and habitat-forming biota and how it is mediated by functional ecology improves our ability to predict and manage changes in the replenishment of marine populations.

  6. Uranium dioxide electrolysis

    Science.gov (United States)

    Willit, James L [Batavia, IL; Ackerman, John P [Prescott, AZ; Williamson, Mark A [Naperville, IL

    2009-12-29

    This is a single stage process for treating spent nuclear fuel from light water reactors. The spent nuclear fuel, uranium oxide, UO.sub.2, is added to a solution of UCl.sub.4 dissolved in molten LiCl. A carbon anode and a metallic cathode is positioned in the molten salt bath. A power source is connected to the electrodes and a voltage greater than or equal to 1.3 volts is applied to the bath. At the anode, the carbon is oxidized to form carbon dioxide and uranium chloride. At the cathode, uranium is electroplated. The uranium chloride at the cathode reacts with more uranium oxide to continue the reaction. The process may also be used with other transuranic oxides and rare earth metal oxides.

  7. Uranium dioxide pellets

    International Nuclear Information System (INIS)

    Zawidzki, T.W.

    1982-01-01

    A process for the preparation of a sintered, high density, large crystal grain size uranium dioxide pellet is described which involves: (i) reacting a uranyl nitrate of formula UO 2 (NO 3 ) 2 .6H 2 O with a sulphur source, at a temperature of from about 300 deg. C to provide a sulphur-containing uranium trioxide; (ii) reacting the thus-obtained modified uranium trioxide with ammonium nitrate to form an insoluble sulphur-containing ammonium uranate; (iii) neutralizing the thus-formed slurry with ammonium hydroxide to precipitate out as an insoluble ammonium uranate the remaining dissolved uranium; (iv) recovering the thus-formed precipitates in a dry state; (v) reducing the dry precipitate to UO 2 , and forming it into 'green' pellets; and (vi) sintering the pellets in a hydrogen atmosphere at an elevated temperature

  8. Uranium dioxide calcining apparatus

    International Nuclear Information System (INIS)

    Cole, E.A.; Peterson, R.S.

    1978-01-01

    This invention relates to an improved continuous calcining apparatus for consistently and controllably producing from calcinable reactive solid compounds of uranium, such as ammonium diuranate, uranium dioxide (UO 2 ) having an oxygen to uranium ratio of less than 2.2. The apparatus comprises means at the outlet end of a calciner kiln for receiving hot UO 2 , means for cooling the UO 2 to a temperature of below 100 deg C and conveying the cooled UO 2 to storage or to subsequent UO 2 processing apparatus where it finally comes into contact with air, the means for receiving cooling and conveying being sealed to the outlet end of the calciner and being maintained full of UO 2 and so operable as to exclude atmospheric oxygen from coming into contact with any UO 2 which is at elevated temperatures where it would readily oxidize, without the use of extra hydrogen gas in said means. (author)

  9. Paleoclimate from ice cores : abrupt climate change and the prolonged Holocene

    International Nuclear Information System (INIS)

    White, J.W.C.

    2001-01-01

    Ice cores provide valuable information about the Earth's past climates and past environments. They can also help in predicting future climates and the nature of climate change. Recent findings in ice cores have shown large and abrupt climate changes in the past. This paper addressed abrupt climate changes and the peculiar nature of the Holocene. An abrupt climate change is a shift of 5 degrees C in mean annual temperature in less than 50 years. This is considered to be the most threatening aspect of potential future climate change since it leaves very little time for adaptation by humans or any other part of the Earth's ecosystem. This paper also discussed the arrival of the next glacial period. In the past 50 years, scientists have recognized the importance of the Earth's orbit around the sun in pacing the occurrence of large ice sheets. The timing of orbital forcing suggests that the Earth is overdue for the next major glaciation. The reason for this anomaly was discussed. Abrupt climate shifts seem to be caused by mode changes in sensitive points in the climate system, such as the North Atlantic Deep Water Formation and its impact on sea ice cover in the North Atlantic. These changes have been observed in ice cores in Greenland but they are not restricted to Greenland. Evidence from Antarctic ice cores suggest that abrupt climate change may also occur in the Southern Hemisphere. The Vostok ice core in Antarctica indicates that the 11,000 year long interglacial period that we are in right now is longer than the previous four interglacial periods. The Holocene epoch is unique because both methane and carbon dioxide rise in the last 6,000 years, an atypical response from these greenhouse gases during an interglacial period. It was suggested that the rise in methane can be attributed to human activities. 13 refs., 2 figs

  10. Climate change effects on regions of Canada

    International Nuclear Information System (INIS)

    Bruce, J.P.

    2002-01-01

    This report describes the major effects of climatic change being experienced in different parts of Canada, and emphasizes those that they are likely to become so severe that they may disrupt social, ecological and economic systems. The report notes that the driving force behind these impacts is change in temperature, precipitation, and in extreme weather events. The report strongly suggests that greenhouse gas emissions, particularly carbon dioxide, methane and nitrous oxide will likely continue to increase due to human activities such as burning of fossil fuels for heating, cooling and transportation. Loss of tropical forests is also listed as a cause for increased greenhouse gases. In order to reduce greenhouse gas emissions into the atmosphere, Canada must use energy much more efficiently, use more alternative renewable energy source and substitute natural gas for coal and oil whenever possible. It was emphasized that the ratification of the Kyoto Protocol would slow down the rate of increase of the world's greenhouse gas emissions, which in turn affect atmospheric concentrations. The author states that Canada's ratification of the Kyoto Protocol is key to global success, particularly since some countries have backed away from it and some are wavering. The report outlined the following major impacts of climate change in various parts of Canada: sea ice, permafrost, forest fires, transportation, toxic contaminants, storminess, precipitation, water supply, water quality, fisheries, hydropower, agriculture and human adaptation. refs., tabs

  11. Environmental and societal consequences of a possible CO/sub 2/-induced climate change. Volume II, Part 8. Impacts of rising atmospheric carbon dioxide levels on agricultural growing seasons and crop water use efficiencies

    Energy Technology Data Exchange (ETDEWEB)

    Newman, J. E.

    1982-09-01

    The researchable areas addressed relate to the possible impacts of climate change on agricultural growing seasons and crop adaptation responses on a global basis. The research activities proposed are divided into the following two main areas of investigation: anticipated climate change impacts on the physical environmental characteristics of the agricultural growing seasons and, the most probable food crop responses to the possible changes in atmospheric CO/sub 2/ levels in plant environments. The main physical environmental impacts considered are the changes in temperature, or more directly, thermal energy levels and the growing season evapotranspiration-precipitation balances. The resulting food crop, commercial forest and rangeland species response impacts addressed relate to potential geographical shifts in agricultural growing seasons as determined by the length in days of the frost free period, thermal energy changes and water balance changes. In addition, the interaction of possible changes in plant water use efficiencies during the growing season in relationship to changing atmospheric CO/sub 2/ concentrations, is also considered under the scenario of global warming due to increases in atmospheric CO/sub 2/ concentration. These proposed research investigations are followed by adaptive response evaluations.

  12. Secular trends and climate drift in coupled ocean-atmosphere general circulation models

    Science.gov (United States)

    Covey, Curt; Gleckler, Peter J.; Phillips, Thomas J.; Bader, David C.

    2006-02-01

    Coupled ocean-atmosphere general circulation models (coupled GCMs) with interactive sea ice are the primar