Linking an ecosystem model and a landscape model to study forest species response to climate warming

Science.gov (United States)

Hong S. He; David J. Mladenoff; Thomas R. Crow

1999-01-01

No single model can address forest change from single tree to regional scales. We discuss a framework linking an ecosystem process model {LINKAGES) with a spatial landscape model (LANDIS) to examine forest species responses to climate warming for a large, heterogeneous landscape in northern Wisconsin, USA. Individual species response at the ecosystem scale was...

An unexpected role for mixotrophs in the response of peatland carbon cycling to climate warming.

Science.gov (United States)

Jassey, Vincent E J; Signarbieux, Constant; Hättenschwiler, Stephan; Bragazza, Luca; Buttler, Alexandre; Delarue, Frédéric; Fournier, Bertrand; Gilbert, Daniel; Laggoun-Défarge, Fatima; Lara, Enrique; Mills, Robert T E; Mitchell, Edward A D; Payne, Richard J; Robroek, Bjorn J M

2015-11-25

Mixotrophic protists are increasingly recognized for their significant contribution to carbon (C) cycling. As phototrophs they contribute to photosynthetic C fixation, whilst as predators of decomposers, they indirectly influence organic matter decomposition. Despite these direct and indirect effects on the C cycle, little is known about the responses of peatland mixotrophs to climate change and the potential consequences for the peatland C cycle. With a combination of field and microcosm experiments, we show that mixotrophs in the Sphagnum bryosphere play an important role in modulating peatland C cycle responses to experimental warming. We found that five years of consecutive summer warming with peaks of +2 to +8°C led to a 50% reduction in the biomass of the dominant mixotrophs, the mixotrophic testate amoebae (MTA). The biomass of other microbial groups (including decomposers) did not change, suggesting MTA to be particularly sensitive to temperature. In a microcosm experiment under controlled conditions, we then manipulated the abundance of MTA, and showed that the reported 50% reduction of MTA biomass in the field was linked to a significant reduction of net C uptake (-13%) of the entire Sphagnum bryosphere. Our findings suggest that reduced abundance of MTA with climate warming could lead to reduced peatland C fixation.

Temperature response of soil respiration largely unaltered with experimental warming

Science.gov (United States)

Carey, Joanna C.; Tang, Jianwu; Templer, Pamela H.; Kroeger, Kevin D.; Crowther, Thomas W.; Burton, Andrew J.; Dukes, Jeffrey S.; Emmett, Bridget; Frey, Serita D.; Heskel, Mary A.; Jiang, Lifen; Machmuller, Megan B.; Mohan, Jacqueline; Panetta, Anne Marie; Reich, Peter B.; Reinsch, Sabine; Wang, Xin; Allison, Steven D.; Bamminger, Chris; Bridgham, Scott; Collins, Scott L.; de Dato, Giovanbattista; Eddy, William C.; Enquist, Brian J.; Estiarte, Marc; Harte, John; Henderson, Amanda; Johnson, Bart R.; Steenberg Larsen, Klaus; Luo, Yiqi; Marhan, Sven; Melillo, Jerry M.; Penuelas, Josep; Pfeifer-Meister, Laurel; Poll, Christian; Rastetter, Edward B.; Reinmann, Andrew B.; Reynolds, Lorien L.; Schmidt, Inger K.; Shaver, Gaius R.; Strong, Aaron L.; Suseela, Vidya; Tietema, Albert

2016-01-01

The respiratory release of carbon dioxide (CO2) from soil is a major yet poorly understood flux in the global carbon cycle. Climatic warming is hypothesized to increase rates of soil respiration, potentially fueling further increases in global temperatures. However, despite considerable scientific attention in recent decades, the overall response of soil respiration to anticipated climatic warming remains unclear. We synthesize the largest global dataset to date of soil respiration, moisture, and temperature measurements, totaling >3,800 observations representing 27 temperature manipulation studies, spanning nine biomes and over 2 decades of warming. Our analysis reveals no significant differences in the temperature sensitivity of soil respiration between control and warmed plots in all biomes, with the exception of deserts and boreal forests. Thus, our data provide limited evidence of acclimation of soil respiration to experimental warming in several major biome types, contrary to the results from multiple single-site studies. Moreover, across all nondesert biomes, respiration rates with and without experimental warming follow a Gaussian response, increasing with soil temperature up to a threshold of ∼25 °C, above which respiration rates decrease with further increases in temperature. This consistent decrease in temperature sensitivity at higher temperatures demonstrates that rising global temperatures may result in regionally variable responses in soil respiration, with colder climates being considerably more responsive to increased ambient temperatures compared with warmer regions. Our analysis adds a unique cross-biome perspective on the temperature response of soil respiration, information critical to improving our mechanistic understanding of how soil carbon dynamics change with climatic warming.

Provenance-specific growth responses to drought and air warming in three European oak species

Energy Technology Data Exchange (ETDEWEB)

Arend, Matthias; Kuster, Thomas; Gunthardt-Goerg, Madeleine S.; Dobbertin, Matthias

2011-03-15

This study evaluated oak growth responses to air warming through research conducted with species coming from climatically different sites submitted to differing climates including periodic drought and air warming. Results showed different responses to drought and air warming as an adaptation to the conditions, and differences in growth response from one provenance to another were found but local climate factors were not responsible. This study highlighted that provenance was important to growth responses and it will have to be taken into account for regeneration of oaks in a changed climate if these results are confirmed.

Do cities simulate climate change? A comparison of herbivore response to urban and global warming

Science.gov (United States)

Youngsteadt, Elsa; Dale, Adam G.; Terando, Adam; Dunn, Robert R.; Frank, Steven D.

2014-01-01

Cities experience elevated temperature, CO2, and nitrogen deposition decades ahead of the global average, such that biological response to urbanization may predict response to future climate change. This hypothesis remains untested due to a lack of complementary urban and long-term observations. Here, we examine the response of an herbivore, the scale insect Melanaspis tenebricosa, to temperature in the context of an urban heat island, a series of historical temperature fluctuations, and recent climate warming. We survey M. tenebricosa on 55 urban street trees in Raleigh, NC, 342 herbarium specimens collected in the rural southeastern United States from 1895 to 2011, and at 20 rural forest sites represented by both modern (2013) and historical samples. We relate scale insect abundance to August temperatures and find that M. tenebricosa is most common in the hottest parts of the city, on historical specimens collected during warm time periods, and in present-day rural forests compared to the same sites when they were cooler. Scale insects reached their highest densities in the city, but abundance peaked at similar temperatures in urban and historical datasets and tracked temperature on a decadal scale. Although urban habitats are highly modified, species response to a key abiotic factor, temperature, was consistent across urban and rural-forest ecosystems. Cities may be an appropriate but underused system for developing and testing hypotheses about biological effects of climate change. Future work should test the applicability of this model to other groups of organisms.

Differentiated responses of apple tree floral phenology to global warming in contrasting climatic regions

Directory of Open Access Journals (Sweden)

Jean-Michel eLegave

2015-12-01

Full Text Available The responses of flowering phenology to temperature increases in temperate fruit trees have rarely been investigated in contrasting climatic regions. This is an appropriate framework for highlighting varying responses to diverse warming contexts, which would potentially combine chill accumulation declines and heat accumulation increases. To examine this issue, a data set was constituted in apple tree from flowering dates collected for two phenological stages of three cultivars in seven climate-contrasting temperate regions of Western Europe and in three mild regions, one in Northern Morocco and two in Southern Brazil. Multiple change-point models were applied to flowering date series, as well as to corresponding series of mean temperature during two successive periods, respectively determining for the fulfillment of chill and heat requirements. A new overview in space and time of flowering date changes was provided in apple tree highlighting not only flowering date advances as in previous studies but also stationary flowering date series. At global scale, differentiated flowering time patterns result from varying interactions between contrasting thermal determinisms of flowering dates and contrasting warming contexts. This may explain flowering date advances in most of European regions and in Morocco vs. stationary flowering date series in the Brazilian regions. A notable exception in Europe was found in the French Mediterranean region where the flowering date series was stationary. While the flowering duration series were stationary whatever the region, the flowering durations were far longer in mild regions compared to temperate regions. Our findings suggest a new warming vulnerability in temperate Mediterranean regions, which could shift towards responding more to chill decline and consequently experience late and extended flowering under future warming scenarios.

Differentiated Responses of Apple Tree Floral Phenology to Global Warming in Contrasting Climatic Regions.

Science.gov (United States)

Legave, Jean-Michel; Guédon, Yann; Malagi, Gustavo; El Yaacoubi, Adnane; Bonhomme, Marc

2015-01-01

The responses of flowering phenology to temperature increases in temperate fruit trees have rarely been investigated in contrasting climatic regions. This is an appropriate framework for highlighting varying responses to diverse warming contexts, which would potentially combine chill accumulation (CA) declines and heat accumulation (HA) increases. To examine this issue, a data set was constituted in apple tree from flowering dates collected for two phenological stages of three cultivars in seven climate-contrasting temperate regions of Western Europe and in three mild regions, one in Northern Morocco and two in Southern Brazil. Multiple change-point models were applied to flowering date series, as well as to corresponding series of mean temperature during two successive periods, respectively determining for the fulfillment of chill and heat requirements. A new overview in space and time of flowering date changes was provided in apple tree highlighting not only flowering date advances as in previous studies but also stationary flowering date series. At global scale, differentiated flowering time patterns result from varying interactions between contrasting thermal determinisms of flowering dates and contrasting warming contexts. This may explain flowering date advances in most of European regions and in Morocco vs. stationary flowering date series in the Brazilian regions. A notable exception in Europe was found in the French Mediterranean region where the flowering date series was stationary. While the flowering duration series were stationary whatever the region, the flowering durations were far longer in mild regions compared to temperate regions. Our findings suggest a new warming vulnerability in temperate Mediterranean regions, which could shift toward responding more to chill decline and consequently experience late and extended flowering under future warming scenarios.

Changing forest water yields in response to climate warming: results from long-term experimental watershed sites across North America

Science.gov (United States)

Creed, Irena F; Spargo, Adam T; Jones, Julia A; Buttle, Jim M; Adams, Mary B; Beall, Fred D; Booth, Eric G; Campbell, John L; Clow, Dave; Elder, Kelly; Green, Mark B; Grimm, Nancy B; Miniat, Chelcy; Ramlal, Patricia; Saha, Amartya; Sebestyen, Stephen; Spittlehouse, Dave; Sterling, Shannon; Williams, Mark W; Winkler, Rita; Yao, Huaxia

2014-01-01

Climate warming is projected to affect forest water yields but the effects are expected to vary. We investigated how forest type and age affect water yield resilience to climate warming. To answer this question, we examined the variability in historical water yields at long-term experimental catchments across Canada and the United States over 5-year cool and warm periods. Using the theoretical framework of the Budyko curve, we calculated the effects of climate warming on the annual partitioning of precipitation (P) into evapotranspiration (ET) and water yield. Deviation (d) was defined as a catchment's change in actual ET divided by P [AET/P; evaporative index (EI)] coincident with a shift from a cool to a warm period – a positive d indicates an upward shift in EI and smaller than expected water yields, and a negative d indicates a downward shift in EI and larger than expected water yields. Elasticity was defined as the ratio of interannual variation in potential ET divided by P (PET/P; dryness index) to interannual variation in the EI – high elasticity indicates low d despite large range in drying index (i.e., resilient water yields), low elasticity indicates high d despite small range in drying index (i.e., nonresilient water yields). Although the data needed to fully evaluate ecosystems based on these metrics are limited, we were able to identify some characteristics of response among forest types. Alpine sites showed the greatest sensitivity to climate warming with any warming leading to increased water yields. Conifer forests included catchments with lowest elasticity and stable to larger water yields. Deciduous forests included catchments with intermediate elasticity and stable to smaller water yields. Mixed coniferous/deciduous forests included catchments with highest elasticity and stable water yields. Forest type appeared to influence the resilience of catchment water yields to climate warming, with conifer and deciduous catchments more susceptible to

Different ecophysiological responses of freshwater fish to warming and acidification.

Science.gov (United States)

Jesus, Tiago F; Rosa, Inês C; Repolho, Tiago; Lopes, Ana R; Pimentel, Marta S; Almeida-Val, Vera M F; Coelho, Maria M; Rosa, Rui

2018-02-01

Future climate change scenarios predict threatening outcomes to biodiversity. Available empirical data concerning biological response of freshwater fish to climate change remains scarce. In this study, we investigated the physiological and biochemical responses of two Iberian freshwater fish species (Squalius carolitertii and the endangered S. torgalensis), inhabiting different climatic conditions, to projected future scenarios of warming (+3°C) and acidification (ΔpH=-0.4). Herein, metabolic enzyme activities of glycolytic (citrate synthase - CS, lactate dehydrogenase - LDH) and antioxidant (glutathione S-transferase, catalase and superoxide dismutase) pathways, as well as the heat shock response (HSR) and lipid peroxidation were determined. Our results show that, under current water pH, warming causes differential interspecific changes on LDH activity, increasing and decreasing its activity in S. carolitertii and in S. torgalensis, respectively. Furthermore, the synergistic effect of warming and acidification caused an increase in LDH activity of S. torgalensis, comparing with the warming condition. As for CS activity, acidification significantly decreased its activity in S. carolitertii whereas in S. torgalensis no significant effect was observed. These results suggest that S. carolitertii is more vulnerable to climate change, possibly as the result of its evolutionary acclimatization to milder climatic condition, while S. torgalensis evolved in the warmer Mediterranean climate. However, significant changes in HSR were observed under the combined warming and acidification (S. carolitertii) or under acidification (S. torgalensis). Our results underlie the importance of conducting experimental studies and address species endpoint responses under projected climate change scenarios to improve conservation strategies, and to safeguard endangered freshwater fish. Copyright © 2017 Elsevier Inc. All rights reserved.

Soil microbial responses to climate warming in Northern Andean alpine ecosystems

Science.gov (United States)

Gallery, R. E.; Lasso, E.

2017-12-01

The historically cooler temperatures and waterlogged soils of tropical alpine grasslands (páramo) have resulted in low decomposition rates and a large buildup of organic matter, making páramo one of the most important carbon sinks in tropical biomes. The climatic factors that favored the carbon accumulation are changing, and as a result páramo could play a disproportionate role in driving climate feedbacks through increased carbon released from these large soil carbon stores. Open top chamber warming experiments were established in the Colombian Andes in 2016 to quantify the magnitude of climate change on carbon balance and identify microbial and plant traits that regulate these impacts. Two focal sites differ in mean annual temperature, precipitation, and plant community richness. Heterotrophic respiration (RH,) was measured from soil cores incubated at temperatures representing current and projected warming. The warming effect on RH was sensitive to soil moisture, which could reflect shifts in microbial community composition and/or extracellular enzyme production or efficiency as soils dry. Bacterial, archaeal, and fungal communities in ambient and warmed plots were measured through high-throughput amplicon sequencing of the 16S rRNA and ITS1 rRNA gene regions. Communities showed strong spatial structuring both within and among páramo, reflecting the topographic heterogeneity of these ecosystems. Significant differences in relative abundance of dominant microbial taxa between páramo could be largely explained by soil bulk density, water holding capacity, and non-vascular plant cover. Phototrophs common to anoxic soils (e.g., Rhodospirillaceae, Hyphomicrobiaceae) were abundant. Taxa within Euryarchaeota were recovered, suggesting methanogenesis potential. Exploration of the magnitude and temperature sensitivity of methane flux is needed in these seasonally anoxic soils whose dynamics could have significant implications for the global climate system.

Do cities simulate climate change? A comparison of herbivore response to urban and global warming.

Science.gov (United States)

Youngsteadt, Elsa; Dale, Adam G; Terando, Adam J; Dunn, Robert R; Frank, Steven D

2015-01-01

Cities experience elevated temperature, CO2 , and nitrogen deposition decades ahead of the global average, such that biological response to urbanization may predict response to future climate change. This hypothesis remains untested due to a lack of complementary urban and long-term observations. Here, we examine the response of an herbivore, the scale insect Melanaspis tenebricosa, to temperature in the context of an urban heat island, a series of historical temperature fluctuations, and recent climate warming. We survey M. tenebricosa on 55 urban street trees in Raleigh, NC, 342 herbarium specimens collected in the rural southeastern United States from 1895 to 2011, and at 20 rural forest sites represented by both modern (2013) and historical samples. We relate scale insect abundance to August temperatures and find that M. tenebricosa is most common in the hottest parts of the city, on historical specimens collected during warm time periods, and in present-day rural forests compared to the same sites when they were cooler. Scale insects reached their highest densities in the city, but abundance peaked at similar temperatures in urban and historical datasets and tracked temperature on a decadal scale. Although urban habitats are highly modified, species response to a key abiotic factor, temperature, was consistent across urban and rural-forest ecosystems. Cities may be an appropriate but underused system for developing and testing hypotheses about biological effects of climate change. Future work should test the applicability of this model to other groups of organisms. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.

Specificity Responses of Grasshoppers in Temperate Grasslands to Diel Asymmetric Warming

Science.gov (United States)

Wu, Tingjuan; Hao, Shuguang; Sun, Osbert Jianxin; Kang, Le

2012-01-01

Background Global warming is characterized by not only an increase in the daily mean temperature, but also a diel asymmetric pattern. However, most of the current studies on climate change have only concerned with the mean values of the warming trend. Although many studies have been conducted concerning the responses of insects to climate change, studies that address the issue of diel asymmetric warming under field conditions are not found in the literature. Methodology/Principal Findings We conducted a field climate manipulative experiment and investigated developmental and demographic responses to diel asymmetric warming in three grasshopper species (an early-season species Dasyhippus barbipes, a mid-season species Oedaleus asiaticus, and a late-season species Chorthippus fallax). It was found that warming generally advanced the development of eggs and nymphs, but had no apparent impacts on the hatching rate of eggs, the emergence rate of nymphs and the survival and fecundity of adults in all the three species. Nighttime warming was more effective in advancing egg development than the daytime warming. The emergence time of adults was differentially advanced by warming in the three species; it was advanced by 5.64 days in C. fallax, 3.55 days in O. asiaticus, and 1.96 days in D. barbipes. This phenological advancement was associated with increases in the effective GDDs accumulation. Conclusions/Significance Results in this study indicate that the responses of the three grasshopper species to warming are influenced by several factors, including species traits, developmental stage, and the thermal sensitivity of the species. Moreover, species with diapausing eggs are less responsive to changes in temperature regimes, suggesting that development of diapausing eggs is a protective mechanism in early-season grasshopper for avoiding the risk of pre-winter hatching. Our results highlight the need to consider the complex relationships between climate change and

Topography and age mediate the growth responses of Smith fir to climate warming in the southeastern Tibetan Plateau.

Science.gov (United States)

Liu, B; Wang, Y; Zhu, H; Liang, E; Camarero, J J

2016-10-01

The Tibetan Plateau holds some of the world's highest undisturbed natural treelines and timberlines. Such extreme environments constitute potentially valuable monitoring sites of the effects of climate warming on high-elevation forests. Here, we analyze a network of 21 Smith fir forests situated in the Sygera Mountains, southeastern Tibetan Plateau, using tree-ring width (TRW) and basal area increment (BAI) chronologies. Sampled sites encompassed a wide elevation gradient, from 3600 to 4400 m, including some treeline sites and diverse aspects and tree ages. In comparison with TRW series, BAI series better capture the long-term warming signal. Previous November and current April and summer temperatures are the dominant climatic factors controlling Smith fir radial growth. The mean inter-series correlations of TRW increased upwards, but the forest limit presented the highest potential to reconstruct past temperature variability. Moreover, the growth responses of young trees were less stable than those of trees older than 100 years. Climate warming is accelerating radial growth of Smith fir forest subjected to mesic conditions. Collectively, these findings confirm that the effects of site elevation and tree age should be considered when quantifying climate-growth relationships. The type of tree-ring data (BAI vs. TRW) is also relevant since BAI indices seem to be a better climatic proxy of low-frequency temperature signals than TRW indices. Therefore, site (e.g., elevation) and tree (e.g., age) features should be considered to properly evaluate the effects of climate warming on growth of high-elevation forests.

Topography and age mediate the growth responses of Smith fir to climate warming in the southeastern Tibetan Plateau

Science.gov (United States)

Liu, B.; Wang, Y.; Zhu, H.; Liang, E.; Camarero, J. J.

2016-10-01

The Tibetan Plateau holds some of the world's highest undisturbed natural treelines and timberlines. Such extreme environments constitute potentially valuable monitoring sites of the effects of climate warming on high-elevation forests. Here, we analyze a network of 21 Smith fir forests situated in the Sygera Mountains, southeastern Tibetan Plateau, using tree-ring width (TRW) and basal area increment (BAI) chronologies. Sampled sites encompassed a wide elevation gradient, from 3600 to 4400 m, including some treeline sites and diverse aspects and tree ages. In comparison with TRW series, BAI series better capture the long-term warming signal. Previous November and current April and summer temperatures are the dominant climatic factors controlling Smith fir radial growth. The mean inter-series correlations of TRW increased upwards, but the forest limit presented the highest potential to reconstruct past temperature variability. Moreover, the growth responses of young trees were less stable than those of trees older than 100 years. Climate warming is accelerating radial growth of Smith fir forest subjected to mesic conditions. Collectively, these findings confirm that the effects of site elevation and tree age should be considered when quantifying climate-growth relationships. The type of tree-ring data (BAI vs. TRW) is also relevant since BAI indices seem to be a better climatic proxy of low-frequency temperature signals than TRW indices. Therefore, site (e.g., elevation) and tree (e.g., age) features should be considered to properly evaluate the effects of climate warming on growth of high-elevation forests.

Global assessment of experimental climate warming on tundra vegetation: heterogeneity over space and time

Science.gov (United States)

Sarah C. Elmendorf; Gregory H.R. Henry; Robert D. Hollister; Robert G. Björk; Anne D. Bjorkman; Terry V. Callaghan; [and others] NO-VALUE; William Gould; Joel Mercado

2012-01-01

Understanding the sensitivity of tundra vegetation to climate warming is critical to forecasting future biodiversity and vegetation feedbacks to climate. In situ warming experiments accelerate climate change on a small scale to forecast responses of local plant communities. Limitations of this approach include the apparent site-specificity of results and uncertainty...

Evaluating the Dominant Components of Warming in Pliocene Climate Simulations

Science.gov (United States)

Hill, D. J.; Haywood, A. M.; Lunt, D. J.; Hunter, S. J.; Bragg, F. J.; Contoux, C.; Stepanek, C.; Sohl, L.; Rosenbloom, N. A.; Chan, W.-L.;

The European climate under a 2 °C global warming

International Nuclear Information System (INIS)

Vautard, Robert; Stegehuis, Annemiek; Gobiet, Andreas; Mendlik, Thomas; Sobolowski, Stefan; Kjellström, Erik; Nikulin, Grigory; Watkiss, Paul; Landgren, Oskar; Teichmann, Claas; Jacob, Daniela

2014-01-01

A global warming of 2 °C relative to pre-industrial climate has been considered as a threshold which society should endeavor to remain below, in order to limit the dangerous effects of anthropogenic climate change. The possible changes in regional climate under this target level of global warming have so far not been investigated in detail. Using an ensemble of 15 regional climate simulations downscaling six transient global climate simulations, we identify the respective time periods corresponding to 2 °C global warming, describe the range of projected changes for the European climate for this level of global warming, and investigate the uncertainty across the multi-model ensemble. Robust changes in mean and extreme temperature, precipitation, winds and surface energy budgets are found based on the ensemble of simulations. The results indicate that most of Europe will experience higher warming than the global average. They also reveal strong distributional patterns across Europe, which will be important in subsequent impact assessments and adaptation responses in different countries and regions. For instance, a North–South (West–East) warming gradient is found for summer (winter) along with a general increase in heavy precipitation and summer extreme temperatures. Tying the ensemble analysis to time periods with a prescribed global temperature change rather than fixed time periods allows for the identification of more robust regional patterns of temperature changes due to removal of some of the uncertainty related to the global models’ climate sensitivity. (paper)

Climate change - global warming

International Nuclear Information System (INIS)

Ciconkov, Risto

2001-01-01

An explanation about climate, weather, climate changes. What is a greenhouse effect, i.e. global warming and reasons which contribute to this effect. Greenhouse gases (GHG) and GWP (Global Warming Potential) as a factor for estimating their influence on the greenhouse effect. Indicators of the climate changes in the previous period by known international institutions, higher concentrations of global average temperature. Projecting of likely scenarios for the future climate changes and consequences of them on the environment and human activities: industry, energy, agriculture, water resources. The main points of the Kyoto Protocol and problems in its realization. The need of preparing a country strategy concerning the acts of the Kyoto Protocol, suggestions which could contribute in the preparation of the strategy. A special attention is pointed to the energy, its resources, the structure of energy consumption and the energy efficiency. (Author)

Can biomass responses to warming at plant to ecosystem levels be predicted by leaf-level responses?

Science.gov (United States)

Xia, J.; Shao, J.; Zhou, X.; Yan, W.; Lu, M.

2015-12-01

Global warming has the profound impacts on terrestrial C processes from leaf to ecosystem scales, potentially feeding back to climate dynamics. Although numerous studies had investigated the effects of warming on C processes from leaf to plant and ecosystem levels, how leaf-level responses to warming scale up to biomass responses at plant, population, and community levels are largely unknown. In this study, we compiled a dataset from 468 papers at 300 experimental sites and synthesized the warming effects on leaf-level parameters, and plant, population and ecosystem biomass. Our results showed that responses of plant biomass to warming mainly resulted from the changed leaf area rather than the altered photosynthetic capacity. The response of ecosystem biomass to warming was weaker than those of leaf area and plant biomass. However, the scaling functions from responses of leaf area to plant biomass to warming were different in diverse forest types, but functions were similar in non-forested biomes. In addition, it is challenging to scale the biomass responses from plant up to ecosystem. These results indicated that leaf area might be the appropriate index for plant biomass response to warming, and the interspecific competition might hamper the scaling of the warming effects on plant and ecosystem levels, suggesting that the acclimation capacity of plant community should be incorporated into land surface models to improve the prediction of climate-C cycle feedback.

Quantifying global soil carbon losses in response to warming.

Science.gov (United States)

Crowther, T W; Todd-Brown, K E O; Rowe, C W; Wieder, W R; Carey, J C; Machmuller, M B; Snoek, B L; Fang, S; Zhou, G; Allison, S D; Blair, J M; Bridgham, S D; Burton, A J; Carrillo, Y; Reich, P B; Clark, J S; Classen, A T; Dijkstra, F A; Elberling, B; Emmett, B A; Estiarte, M; Frey, S D; Guo, J; Harte, J; Jiang, L; Johnson, B R; Kröel-Dulay, G; Larsen, K S; Laudon, H; Lavallee, J M; Luo, Y; Lupascu, M; Ma, L N; Marhan, S; Michelsen, A; Mohan, J; Niu, S; Pendall, E; Peñuelas, J; Pfeifer-Meister, L; Poll, C; Reinsch, S; Reynolds, L L; Schmidt, I K; Sistla, S; Sokol, N W; Templer, P H; Treseder, K K; Welker, J M; Bradford, M A

2016-11-30

The majority of the Earth's terrestrial carbon is stored in the soil. If anthropogenic warming stimulates the loss of this carbon to the atmosphere, it could drive further planetary warming. Despite evidence that warming enhances carbon fluxes to and from the soil, the net global balance between these responses remains uncertain. Here we present a comprehensive analysis of warming-induced changes in soil carbon stocks by assembling data from 49 field experiments located across North America, Europe and Asia. We find that the effects of warming are contingent on the size of the initial soil carbon stock, with considerable losses occurring in high-latitude areas. By extrapolating this empirical relationship to the global scale, we provide estimates of soil carbon sensitivity to warming that may help to constrain Earth system model projections. Our empirical relationship suggests that global soil carbon stocks in the upper soil horizons will fall by 30 ± 30 petagrams of carbon to 203 ± 161 petagrams of carbon under one degree of warming, depending on the rate at which the effects of warming are realized. Under the conservative assumption that the response of soil carbon to warming occurs within a year, a business-as-usual climate scenario would drive the loss of 55 ± 50 petagrams of carbon from the upper soil horizons by 2050. This value is around 12-17 per cent of the expected anthropogenic emissions over this period. Despite the considerable uncertainty in our estimates, the direction of the global soil carbon response is consistent across all scenarios. This provides strong empirical support for the idea that rising temperatures will stimulate the net loss of soil carbon to the atmosphere, driving a positive land carbon-climate feedback that could accelerate climate change.

Large extents of intensive land use limit community reorganization during climate warming.

Science.gov (United States)

Oliver, Tom H; Gillings, Simon; Pearce-Higgins, James W; Brereton, Tom; Crick, Humphrey Q P; Duffield, Simon J; Morecroft, Michael D; Roy, David B

2017-06-01

Climate change is increasingly altering the composition of ecological communities, in combination with other environmental pressures such as high-intensity land use. Pressures are expected to interact in their effects, but the extent to which intensive human land use constrains community responses to climate change is currently unclear. A generic indicator of climate change impact, the community temperature index (CTI), has previously been used to suggest that both bird and butterflies are successfully 'tracking' climate change. Here, we assessed community changes at over 600 English bird or butterfly monitoring sites over three decades and tested how the surrounding land has influenced these changes. We partitioned community changes into warm- and cold-associated assemblages and found that English bird communities have not reorganized successfully in response to climate change. CTI increases for birds are primarily attributable to the loss of cold-associated species, whilst for butterflies, warm-associated species have tended to increase. Importantly, the area of intensively managed land use around monitoring sites appears to influence these community changes, with large extents of intensively managed land limiting 'adaptive' community reorganization in response to climate change. Specifically, high-intensity land use appears to exacerbate declines in cold-adapted bird and butterfly species, and prevent increases in warm-associated birds. This has broad implications for managing landscapes to promote climate change adaptation. © 2017 John Wiley & Sons Ltd.

Global assessment of experimental climate warming on tundra vegetation: heterogeneity over space and time.

Science.gov (United States)

Elmendorf, Sarah C; Henry, Gregory H R; Hollister, Robert D; Björk, Robert G; Bjorkman, Anne D; Callaghan, Terry V; Collier, Laura Siegwart; Cooper, Elisabeth J; Cornelissen, Johannes H C; Day, Thomas A; Fosaa, Anna Maria; Gould, William A; Grétarsdóttir, Járngerður; Harte, John; Hermanutz, Luise; Hik, David S; Hofgaard, Annika; Jarrad, Frith; Jónsdóttir, Ingibjörg Svala; Keuper, Frida; Klanderud, Kari; Klein, Julia A; Koh, Saewan; Kudo, Gaku; Lang, Simone I; Loewen, Val; May, Jeremy L; Mercado, Joel; Michelsen, Anders; Molau, Ulf; Myers-Smith, Isla H; Oberbauer, Steven F; Pieper, Sara; Post, Eric; Rixen, Christian; Robinson, Clare H; Schmidt, Niels Martin; Shaver, Gaius R; Stenström, Anna; Tolvanen, Anne; Totland, Orjan; Troxler, Tiffany; Wahren, Carl-Henrik; Webber, Patrick J; Welker, Jeffery M; Wookey, Philip A

2012-02-01

Understanding the sensitivity of tundra vegetation to climate warming is critical to forecasting future biodiversity and vegetation feedbacks to climate. In situ warming experiments accelerate climate change on a small scale to forecast responses of local plant communities. Limitations of this approach include the apparent site-specificity of results and uncertainty about the power of short-term studies to anticipate longer term change. We address these issues with a synthesis of 61 experimental warming studies, of up to 20 years duration, in tundra sites worldwide. The response of plant groups to warming often differed with ambient summer temperature, soil moisture and experimental duration. Shrubs increased with warming only where ambient temperature was high, whereas graminoids increased primarily in the coldest study sites. Linear increases in effect size over time were frequently observed. There was little indication of saturating or accelerating effects, as would be predicted if negative or positive vegetation feedbacks were common. These results indicate that tundra vegetation exhibits strong regional variation in response to warming, and that in vulnerable regions, cumulative effects of long-term warming on tundra vegetation - and associated ecosystem consequences - have the potential to be much greater than we have observed to date. © 2011 Blackwell Publishing Ltd/CNRS.

Personal efficacy, the information environment, and attitudes toward global warming and climate change in the United States.

Science.gov (United States)

Kellstedt, Paul M; Zahran, Sammy; Vedlitz, Arnold

2008-02-01

Despite the growing scientific consensus about the risks of global warming and climate change, the mass media frequently portray the subject as one of great scientific controversy and debate. And yet previous studies of the mass public's subjective assessments of the risks of global warming and climate change have not sufficiently examined public informedness, public confidence in climate scientists, and the role of personal efficacy in affecting global warming outcomes. By examining the results of a survey on an original and representative sample of Americans, we find that these three forces-informedness, confidence in scientists, and personal efficacy-are related in interesting and unexpected ways, and exert significant influence on risk assessments of global warming and climate change. In particular, more informed respondents both feel less personally responsible for global warming, and also show less concern for global warming. We also find that confidence in scientists has unexpected effects: respondents with high confidence in scientists feel less responsible for global warming, and also show less concern for global warming. These results have substantial implications for the interaction between scientists and the public in general, and for the public discussion of global warming and climate change in particular.

Amount and timing of permafrost carbon release in response to climate warming

Energy Technology Data Exchange (ETDEWEB)

Schaefer, Kevin; Zhang, Tingjun; Barrett, Andrew P. (National Snow and Ice Data Center, Cooperative Inst. for Research in Environmental Sciences, Univ. of Colorado at Boulder, Boulder (United States)), e-mail: kevin.schaefer@nsidc.org; Bruhwiler, Lori (National Oceanic and Atmospheric Administration, Earth System Research Laboratory, Boulder (United States))

2011-04-15

The thaw and release of carbon currently frozen in permafrost will increase atmospheric CO{sub 2} concentrations and amplify surface warming to initiate a positive permafrost carbon feedback (PCF) on climate.We use surface weather from three global climate models based on the moderate warming, A1B Intergovernmental Panel on Climate Change emissions scenario and the SiBCASA land surface model to estimate the strength and timing of the PCF and associated uncertainty. By 2200, we predict a 29-59% decrease in permafrost area and a 53-97 cm increase in active layer thickness. By 2200, the PCF strength in terms of cumulative permafrost carbon flux to the atmosphere is 190 +- 64 Gt C. This estimate may be low because it does not account for amplified surface warming due to the PCF itself and excludes some discontinuous permafrost regions where SiBCASA did not simulate permafrost. We predict that the PCF will change the arctic from a carbon sink to a source after the mid-2020s and is strong enough to cancel 42-88% of the total global land sink. The thaw and decay of permafrost carbon is irreversible and accounting for the PCF will require larger reductions in fossil fuel emissions to reach a target atmospheric CO{sub 2} concentration

Is man responsible for global warming?; L'homme est-il responsable du rechauffement climatique?

Energy Technology Data Exchange (ETDEWEB)

Legendre, A

2009-07-01

According to politicians, ecologists and mass media, it is now certain that with our CO{sub 2} emissions, we are all responsible for a major global warming to come with dramatic consequences. But, is this affirmation indisputable? Are we all responsible for the rise of sea level and the summer thawing of the arctic ice shelf? Is this expected global warming without precedent? And is CO{sub 2}, necessary for life, the cause of our misfortune? The answers commonly claimed are maybe more complex in reality and the climate question more subtle than it looks like. This book tries to decode the wheels of the climate machine and the share of human responsibility in climate change. (J.S.)

Doubled volatile organic compound emissions from subarctic tundra under simulated climate warming.

Science.gov (United States)

Faubert, Patrick; Tiiva, Päivi; Rinnan, Asmund; Michelsen, Anders; Holopainen, Jarmo K; Rinnan, Riikka

2010-07-01

*Biogenic volatile organic compound (BVOC) emissions from arctic ecosystems are important in view of their role in global atmospheric chemistry and unknown feedbacks to global warming. These cold ecosystems are hotspots of climate warming, which will be more severe here than averaged over the globe. We assess the effects of climatic warming on non-methane BVOC emissions from a subarctic heath. *We performed ecosystem-based chamber measurements and gas chromatography-mass spectrometry (GC-MS) analyses of the BVOCs collected on adsorbent over two growing seasons at a wet subarctic tundra heath hosting a long-term warming and mountain birch (Betula pubescens ssp. czerepanovii) litter addition experiment. *The relatively low emissions of monoterpenes and sesquiterpenes were doubled in response to an air temperature increment of only 1.9-2.5 degrees C, while litter addition had a minor influence. BVOC emissions were seasonal, and warming combined with litter addition triggered emissions of specific compounds. *The unexpectedly high rate of release of BVOCs measured in this conservative warming scenario is far above the estimates produced by the current models, which underlines the importance of a focus on BVOC emissions during climate change. The observed changes have implications for ecological interactions and feedback effects on climate change via impacts on aerosol formation and indirect greenhouse effects.

Native temperature regime influences soil response to simulated warming

Science.gov (United States)

Timothy G. Whitby; Michael D. Madritch

2013-01-01

Anthropogenic climate change is expected to increase global temperatures and potentially increase soil carbon (C) mineralization, which could lead to a positive feedback between global warming and soil respiration. However the magnitude and spatial variability of belowground responses to warming are not yet fully understood. Some of the variability may depend...

The impact of global warming on the range distribution of different climatic groups of Aspidoscelis costata costata.

Science.gov (United States)

Güizado-Rodríguez, Martha Anahí; Ballesteros-Barrera, Claudia; Casas-Andreu, Gustavo; Barradas-Miranda, Victor Luis; Téllez-Valdés, Oswaldo; Salgado-Ugarte, Isaías Hazarmabeth

2012-12-01

The ectothermic nature of reptiles makes them especially sensitive to global warming. Although climate change and its implications are a frequent topic of detailed studies, most of these studies are carried out without making a distinction between populations. Here we present the first study of an Aspidoscelis species that evaluates the effects of global warming on its distribution using ecological niche modeling. The aims of our study were (1) to understand whether predicted warmer climatic conditions affect the geographic potential distribution of different climatic groups of Aspidoscelis costata costata and (2) to identify potential altitudinal changes of these groups under global warming. We used the maximum entropy species distribution model (MaxEnt) to project the potential distributions expected for the years 2020, 2050, and 2080 under a single simulated climatic scenario. Our analysis suggests that some climatic groups of Aspidoscelis costata costata will exhibit reductions and in others expansions in their distribution, with potential upward shifts toward higher elevation in response to climate warming. Different climatic groups were revealed in our analysis that subsequently showed heterogeneous responses to climatic change illustrating the complex nature of species geographic responses to environmental change and the importance of modeling climatic or geographic groups and/or populations instead of the entire species' range treated as a homogeneous entity.

Dependence of Arctic climate on the latitudinal position of stationary waves and to high-latitudes surface warming

Science.gov (United States)

Shin, Yechul; Kang, Sarah M.; Watanabe, Masahiro

2017-12-01

Previous studies suggest large uncertainties in the stationary wave response under global warming. Here, we investigate how the Arctic climate responds to changes in the latitudinal position of stationary waves, and to high-latitudes surface warming that mimics the effect of Arctic sea ice loss under global warming. To generate stationary waves in an atmospheric model coupled to slab ocean, a series of experiments is performed where the thermal forcing with a zonal wavenumber-2 (with zero zonal-mean) is prescribed at the surface at different latitude bands in the Northern Hemisphere. When the stationary waves are generated in the subtropics, the cooling response dominates over the warming response in the lower troposphere due to cloud radiative effects. Then, the low-level baroclinicity is reduced in the subtropics, which gives rise to a poleward shift of the eddy driven jet, thereby inducing substantial cooling in the northern high latitudes. As the stationary waves are progressively generated at higher latitudes, the zonal-mean climate state gradually becomes more similar to the integration with no stationary waves. These differences in the mean climate affect the Arctic climate response to high-latitudes surface warming. Additional surface heating over the Arctic is imposed to the reference climates in which the stationary waves are located at different latitude bands. When the stationary waves are positioned at lower latitudes, the eddy driven jet is located at higher latitude, closer to the prescribed Arctic heating. As baroclinicity is more effectively perturbed, the jet shifts more equatorward that accompanies a larger reduction in the poleward eddy transport of heat and momentum. A stronger eddy-induced descending motion creates greater warming over the Arctic. Our study calls for a more accurate simulation of the present-day stationary wave pattern to enhance the predictability of the Arctic warming response in a changing climate.

The climate response of the Indo-Pacific warm pool to glacial sea level

Science.gov (United States)

Di Nezio, Pedro N.; Timmermann, Axel; Tierney, Jessica E.; Jin, Fei-Fei; Otto-Bliesner, Bette; Rosenbloom, Nan; Mapes, Brian; Neale, Rich; Ivanovic, Ruza F.; Montenegro, Alvaro

2016-06-01

Growing climate proxy evidence suggests that changes in sea level are important drivers of tropical climate change on glacial-interglacial timescales. These paleodata suggest that rainfall patterns over the Indo-Pacific warm pool (IPWP) are highly sensitive to the landmass configuration of the Maritime Continent and that lowered sea level contributed to large-scale drying during the Last Glacial Maximum (LGM, approximately 21,000 years B.P.). Using the Community Earth System Model Version 1.2 (CESM1), we investigate the mechanisms by which lowered sea level influenced the climate of the IPWP during the LGM. The CESM1 simulations show that, in agreement with previous hypotheses, changes in atmospheric circulation are initiated by the exposure of the Sunda and Sahul shelves. Ocean dynamical processes amplify the changes in atmospheric circulation by increasing the east-west sea surface temperature (SST) gradient along the equatorial Indian Ocean. The coupled mechanism driving this response is akin to the Bjerknes feedback and results in a large-scale climatic reorganization over the Indian Ocean with impacts extending from east Africa to the western tropical Pacific. Unlike exposure of the Sunda shelf, exposure of Sahul shelf and the associated changes in surface albedo play a key role because of the positive feedback. This mechanism could explain the pattern of dry (wet) eastern (western) Indian Ocean identified in climate proxies and LGM simulations. However, this response also requires a strengthened SST gradient along the equatorial Indian Ocean, a pattern that is not evident in marine paleoreconstructions. Strategies to resolve this issue are discussed.

Fungal decomposition of terrestrial organic matter accelerated Early Jurassic climate warming

Science.gov (United States)

Pieńkowski, Grzegorz; Hodbod, Marta; Ullmann, Clemens V.

2016-08-01

Soils - constituting the largest terrestrial carbon pool - are vulnerable to climatic warming. Currently existing uncertainties regarding carbon fluxes within terrestrial systems can be addressed by studies of past carbon cycle dynamics and related climate change recorded in sedimentary successions. Here we show an example from the Early Jurassic (early Toarcian, c. 183 mya) marginal-marine strata from Poland, tracking the hinterland response to climatic changes through a super-greenhouse event. In contrast to anoxia-related enhanced carbon storage in coeval open marine environments, Total Organic Carbon (TOC) concentrations in the Polish successions are substantially reduced during this event. Increasing temperature favoured fungal-mediated decomposition of plant litter - specifically of normally resistant woody tissues. The associated injection of oxidized organic matter into the atmosphere corresponds to abrupt changes in standing vegetation and may have contributed significantly to the amplified greenhouse climate on Earth. The characteristic Toarcian signature of multiple warm pulses coinciding with rapidly decreasing carbon isotope ratios may in part be the result of a radical reduction of the terrestrial carbon pool as a response to climate change.

Tropical forest soil microbes and climate warming: An Andean-Amazon gradient and `SWELTR'

Science.gov (United States)

Nottingham, A.; Turner, B. L.; Fierer, N.; Whitaker, J.; Ostle, N. J.; McNamara, N. P.; Bardgett, R.; Silman, M.; Bååth, E.; Salinas, N.; Meir, P.

2017-12-01

Climate warming predicted for the tropics in the coming century will result in average temperatures under which no closed canopy forest exists today. There is, therefore, great uncertainty associated with the direction and magnitude of feedbacks between tropical forests and our future climate - especially relating to the response of soil microbes and the third of global soil carbon contained in tropical forests. While warming experiments are yet to be performed in tropical forests, natural temperature gradients are powerful tools to investigate temperature effects on soil microbes. Here we draw on studies from a 3.5 km elevation gradient - and 20oC mean annual temperature gradient - in Peruvian tropical forest, to investigate how temperature affects the structure of microbial communities, microbial metabolism, enzymatic activity and soil organic matter cycling. With decreased elevation, soil microbial diversity increased and community composition shifted, from taxa associated with oligotrophic towards copiotrophic traits. A key role for temperature in shaping these patterns was demonstrated by a soil translocation experiment, where temperature-manipulation altered the relative abundance of specific taxa. Functional implications of these community composition shifts were indicated by changes in enzyme activities, the temperature sensitivity of bacterial and fungal growth rates, and the presence of temperature-adapted iso-enzymes at different elevations. Studies from a Peruvian elevation transect indicated that soil microbial communities are adapted to long-term (differences with elevation) and short-term (translocation responses) temperature changes. These findings indicate the potential for adaptation of soil microbes in tropical soils to future climate warming. However, in order to evaluate the sensitivity of these processes to climate warming in lowland forests, in situ experimentation is required. Finally, we describe SWELTR (Soil Warming Experiment in Lowland

Regional climate change and national responsibilities

Science.gov (United States)

Hansen, James; Sato, Makiko

2016-03-01

Global warming over the past several decades is now large enough that regional climate change is emerging above the noise of natural variability, especially in the summer at middle latitudes and year-round at low latitudes. Despite the small magnitude of warming relative to weather fluctuations, effects of the warming already have notable social and economic impacts. Global warming of 2 °C relative to preindustrial would shift the ‘bell curve’ defining temperature anomalies a factor of three larger than observed changes since the middle of the 20th century, with highly deleterious consequences. There is striking incongruity between the global distribution of nations principally responsible for fossil fuel CO2 emissions, known to be the main cause of climate change, and the regions suffering the greatest consequences from the warming, a fact with substantial implications for global energy and climate policies.

Insolation driven biomagnetic response to Holocene Warm Period in semi-arid East Asia

NARCIS (Netherlands)

Liu, S.; Deng, Chenglong; Xiao, Jule; Li, Jinhua; Paterson, Greig; Chang, Liao; Yi, Liang; Qin, Huafeng; Pan, Yongxin; Zhu, Rixiang

2015-01-01

The Holocene Warm Period (HWP) provides valuable insights into the climate system and biotic responses to environmental variability and thus serves as an excellent analogue for future global climate changes. Here we document, for the first time, that warm and wet HWP conditions were highly

Study of landscape change under forest harvesting and climate warming-induced fire disturbance

Science.gov (United States)

S. He Hong; David J. Mladenoff; Eric J. Gustafson

2002-01-01

We examined tree species responses under forest harvesting and an increased fire disturbance scenario due to climate warming in northern Wisconsin where northern hardwood and boreal forests are currently predominant. Individual species response at the ecosystem scale was simulated with a gap model, which integrates soil, climate and species data, stratified by...

Nonlinear Response of the Stratosphere and the North Atlantic-European Climate to Global Warming

Science.gov (United States)

Manzini, E.; Karpechko, A. Yu.; Kornblueh, L.

2018-05-01

The response of the northern winter atmospheric circulation for two consecutive global warming periods of 2 K is examined in a grand ensemble (68 members) of idealized CO2 increase experiments performed with the same climate model. The comparison of the atmospheric responses for the two periods shows remarkable differences, indicating the nonlinearity of the response. The nonlinear signature of the atmospheric and surface responses is reminiscent of the positive phase of the annular mode of variability. The stratospheric vortex response shifts from an easterly wind change for the first 2 K to a westerly wind change for the second 2 K. The North Atlantic storm track shifts poleward only in the second period. A weaker November Arctic amplification during the second period suggests that differences in Arctic sea ice changes can act to trigger the atmospheric nonlinear response. Stratosphere-troposphere coupling thereafter can provide for the persistence of this nonlinearity throughout the winter.

Impact of climate warming on upper layer of the Bering Sea

Science.gov (United States)

Lee, Hyun-Chul; Delworth, Thomas L.; Rosati, Anthony; Zhang, Rong; Anderson, Whit G.; Zeng, Fanrong; Stock, Charles A.; Gnanadesikan, Anand; Dixon, Keith W.; Griffies, Stephen M.

2013-01-01

The impact of climate warming on the upper layer of the Bering Sea is investigated by using a high-resolution coupled global climate model. The model is forced by increasing atmospheric CO2 at a rate of 1% per year until CO2 reaches double its initial value (after 70 years), after which it is held constant. In response to this forcing, the upper layer of the Bering Sea warms by about 2°C in the southeastern shelf and by a little more than 1°C in the western basin. The wintertime ventilation to the permanent thermocline weakens in the western Bering Sea. After CO2 doubling, the southeastern shelf of the Bering Sea becomes almost ice-free in March, and the stratification of the upper layer strengthens in May and June. Changes of physical condition due to the climate warming would impact the pre-condition of spring bio-productivity in the southeastern shelf.

Forecasting wildlife response to rapid warming in the Alaskan Arctic

Science.gov (United States)

Van Hemert, Caroline R.; Flint, Paul L.; Udevitz, Mark S.; Koch, Joshua C.; Atwood, Todd C.; Oakley, Karen L.; Pearce, John M.

2015-01-01

Arctic wildlife species face a dynamic and increasingly novel environment because of climate warming and the associated increase in human activity. Both marine and terrestrial environments are undergoing rapid environmental shifts, including loss of sea ice, permafrost degradation, and altered biogeochemical fluxes. Forecasting wildlife responses to climate change can facilitate proactive decisions that balance stewardship with resource development. In this article, we discuss the primary and secondary responses to physical climate-related drivers in the Arctic, associated wildlife responses, and additional sources of complexity in forecasting wildlife population outcomes. Although the effects of warming on wildlife populations are becoming increasingly well documented in the scientific literature, clear mechanistic links are often difficult to establish. An integrated science approach and robust modeling tools are necessary to make predictions and determine resiliency to change. We provide a conceptual framework and introduce examples relevant for developing wildlife forecasts useful to management decisions.

Dynamical response of the Arctic winter stratosphere to global warming

Science.gov (United States)

Karpechko, A.; Manzini, E.

2017-12-01

Climate models often simulate dynamical warming of the Arctic stratosphere as a response to global warming in association with a strengthening of the deep branch of the Brewer-Dobson circulation; however until now, no satisfactory mechanism for such a response has been suggested. Here we investigate the role of stationary planetary waves in the dynamical response of the Arctic winter stratosphere circulation to global warming by analysing simulations performed with atmosphere-only Coupled Model Intercomparison Project Phase 5 (CMIP5) models driven by prescribed sea surface temperatures (SSTs). We focus on December-February (DJF) because this is the period when the troposphere and stratosphere are strongly coupled. When forced by increased SSTs, all the models analysed here simulate Arctic stratosphere dynamical warming, mostly due to increased upward propagation of quasi-stationary wave number 1, as diagnosed by the meridional eddy heat flux. By analysing intermodel spread in the response we show that the stratospheric warming and increased wave flux to the stratosphere correlate with the strengthening of the zonal winds in subtropics and mid-latitudes near the tropopause- a robust response to global warming. These results support previous studies of future Arctic stratosphere changes and suggest a dynamical warming of the Arctic wintertime polar vortex as the most likely response to global warming.

Changing forest water yields in response to climate warming: results from long-term experimental watershed sites across North America

Science.gov (United States)

Irena F. Creed; Adam T. Spargo; Julia A. Jones; Jim M. Buttle; Mary B. Adams; Fred D. Beall; Eric G. Booth; John L. Campbell; Dave Clow; Kelly Elder; Mark B. Green; Nancy B. Grimm; Chelcy Miniat; Patricia Ramlal; Amartya Saha; Stephen Sebestyen; Dave Spittlehouse; Shannon Sterling; Mark W. Williams; Rita Winkler; Huaxia. Yao

2014-01-01

Climate warming is projected to affect forest water yields but the effects are expected to vary.We investigated how forest type and age affect water yield resilience to climate warming. To answer this question, we examined the variability in historical water yields at long-term experimental catchments across Canada and the United States over 5-year cool and warm...

Temperature response of soil respiration largely unaltered with experimental warming

DEFF Research Database (Denmark)

Carey, Joanna C; Tang, Jianwu; Templer, Pamela H

2016-01-01

The respiratory release of carbon dioxide (CO2) from soil is a major yet poorly understood flux in the global carbon cycle. Climatic warming is hypothesized to increase rates of soil respiration, potentially fueling further increases in global temperatures. However, despite considerable scientific...... attention in recent decades, the overall response of soil respiration to anticipated climatic warming remains unclear. We synthesize the largest global dataset to date of soil respiration, moisture, and temperature measurements, totaling >3,800 observations representing 27 temperature manipulation studies......, spanning nine biomes and over 2 decades of warming. Our analysis reveals no significant differences in the temperature sensitivity of soil respiration between control and warmed plots in all biomes, with the exception of deserts and boreal forests. Thus, our data provide limited evidence of acclimation...

Permafrost degradation and methane: low risk of biogeochemical climate-warming feedback

International Nuclear Information System (INIS)

Gao Xiang; Adam Schlosser, C; Sokolov, Andrei; Anthony, Katey Walter; Zhuang Qianlai; Kicklighter, David

2013-01-01

Climate change and permafrost thaw have been suggested to increase high latitude methane emissions that could potentially represent a strong feedback to the climate system. Using an integrated earth-system model framework, we examine the degradation of near-surface permafrost, temporal dynamics of inundation (lakes and wetlands) induced by hydro-climatic change, subsequent methane emission, and potential climate feedback. We find that increases in atmospheric CH 4 and its radiative forcing, which result from the thawed, inundated emission sources, are small, particularly when weighed against human emissions. The additional warming, across the range of climate policy and uncertainties in the climate-system response, would be no greater than 0.1 ° C by 2100. Further, for this temperature feedback to be doubled (to approximately 0.2 ° C) by 2100, at least a 25-fold increase in the methane emission that results from the estimated permafrost degradation would be required. Overall, this biogeochemical global climate-warming feedback is relatively small whether or not humans choose to constrain global emissions. (letter)

Experimental warming decreases arbuscular mycorrhizal fungal colonization in prairie plants along a Mediterranean climate gradient

Directory of Open Access Journals (Sweden)

Hannah Wilson

2016-06-01

Full Text Available Background: Arbuscular mycorrhizal fungi (AMF provide numerous services to their plant symbionts. Understanding climate change effects on AMF, and the resulting plant responses, is crucial for predicting ecosystem responses at regional and global scales. We investigated how the effects of climate change on AMF-plant symbioses are mediated by soil water availability, soil nutrient availability, and vegetation dynamics. Methods: We used a combination of a greenhouse experiment and a manipulative climate change experiment embedded within a Mediterranean climate gradient in the Pacific Northwest, USA to examine this question. Structural equation modeling (SEM was used to determine the direct and indirect effects of experimental warming on AMF colonization. Results: Warming directly decreased AMF colonization across plant species and across the climate gradient of the study region. Other positive and negative indirect effects of warming, mediated by soil water availability, soil nutrient availability, and vegetation dynamics, canceled each other out. Discussion: A warming-induced decrease in AMF colonization would likely have substantial consequences for plant communities and ecosystem function. Moreover, predicted increases in more intense droughts and heavier rains for this region could shift the balance among indirect causal pathways, and either exacerbate or mitigate the negative, direct effect of increased temperature on AMF colonization.

Climate warming: a loss of variation in populations can accompany reproductive shifts.

Science.gov (United States)

Massot, Manuel; Legendre, Stéphane; Fédérici, Pierre; Clobert, Jean

2017-09-01

The most documented response of organisms to climate warming is a change in the average timing of seasonal activities (phenology). Although we know that these average changes can differ among species and populations, we do not know whether climate warming impacts within-population variation in phenology. Using data from five study sites collected during a 13-year survey, we found that the increase in spring temperatures is associated with a reproductive advance of 10 days in natural populations of common lizards (Zootoca vivipara). Interestingly, we show a correlated loss of variation in reproductive dates within populations. As illustrated by a model, this shortening of the reproductive period can have significant negative effects on population dynamics. Consequently, we encourage tests in other species to assess the generality of decreased variation in phenological responses to climate change. © 2017 The Authors Ecology Letters published by CNRS and John Wiley & Sons Ltd.

Research on trend of warm-humid climate in Central Asia

Science.gov (United States)

Gong, Zhi; Peng, Dailiang; Wen, Jingyi; Cai, Zhanqing; Wang, Tiantian; Hu, Yuekai; Ma, Yaxin; Xu, Junfeng

2017-07-01

Central Asia is a typical arid area, which is sensitive and vulnerable part of climate changes, at the same time, Central Asia is the Silk Road Economic Belt of the core district, the warm-humid climate change will affect the production and economic development of neighboring countries. The average annual precipitation, average anneal temperature and evapotranspiration are the important indexes to weigh the climate change. In this paper, the annual precipitation, annual average temperature and evapotranspiration data of every pixel point in Central Asia are analyzed by using long-time series remote sensing data to analyze the trend of warm and humid conditions. Finally, using the model to analyzed the distribution of warm-dry trend, the warm-wet trend, the cold-dry trend and the cold-wet trend in Central Asia and Xinjiang area. The results showed that most of the regions of Central Asia were warm-humid and warm-dry trends, but only a small number of regions showed warm-dry and cold-dry trends. It is of great significance to study the climatic change discipline and guarantee the ecological safety and improve the ability to cope with climate change in the region. It also provide scientific basis for the formulation of regional climate change program. The first section in your paper

Terrestrial carbon cycle affected by non-uniform climate warming

International Nuclear Information System (INIS)

Jianyang Xia; Yiqi Luo; Jiquan Chen; Shilong Piao; Ciais, Philippe; Shiqiang Wan

2014-01-01

Feedbacks between the terrestrial carbon cycle and climate change could affect many ecosystem functions and services, such as food production, carbon sequestration and climate regulation. The rate of climate warming varies on diurnal and seasonal timescales. A synthesis of global air temperature data reveals a greater rate of warming in winter than in summer in northern mid and high latitudes, and the inverse pattern in some tropical regions. The data also reveal a decline in the diurnal temperature range over 51% of the global land area and an increase over only 13%, because night-time temperatures in most locations have risen faster than daytime temperatures. Analyses of satellite data, model simulations and in situ observations suggest that the impact of seasonal warming varies between regions. For example, spring warming has largely stimulated ecosystem productivity at latitudes between 30 degrees and 90 degrees N, but suppressed productivity in other regions. Contrasting impacts of day- and night-time warming on plant carbon gain and loss are apparent in many regions. We argue that ascertaining the effects of non-uniform climate warming on terrestrial ecosystems is a key challenge in carbon cycle research. (authors)

Climate. Meeting the challenge of global warming

International Nuclear Information System (INIS)

Masson-Delmotte, Valerie; Mann, Michael; Greene, Charles; Salas y Melia, David; Dufresne, Jean-Louis; Journe, Venance; Guegan, Jean-Francois; ); Bopp, Laurent; Magnan, Alexandre; Gattuso, Jean-Pierre; Bally, Rene; Duponnois, Robin; Giodda, Alain; MOATTI, JEAN-PAUL; Recio, Carlos; Santana, Luis; Hulot, Nicolas; Criqui, Patrick; Meritet, Sophie; Jacobson, Mark; Delucchi, Mark; Julliard, Romain; Balibar, Sebastien; Prevot, Anne-Caroline; Colleony, Agathe; Mangin, Loic

2015-01-01

The contributions of this publication first discuss and comment the cost of inaction in front of global warming. The authors deny the existence of a climate pause, explain the existence of harsh winters in Europe in the context of global warming, outline that models developed and used in the 1960 already predicted the present trend, discuss the complex relationships between climate change and health, outline the threats on the oceans (acidification, impact on marine species, level rise) and consequently on mankind. A second set of contributions addresses opportunities to be implemented now: to plant trees along the Sahara, the example of an ecologic island (El Hierro, Canaries Islands), the commitment of communities, associations and citizens, the necessary energy transition, innovation at the service of climate, the role of finances and investments. The third set of contributions addresses perspectives: to do without fossil energies, how to reduce the impact of global warming in cities (by planting trees and closing shutters), the emergence of participative science, arguments against climate sceptics, a difficult change of behaviours

How much would five trillion tonnes of carbon warm the climate?

Science.gov (United States)

Tokarska, Katarzyna Kasia; Gillett, Nathan P.; Weaver, Andrew J.; Arora, Vivek K.

2016-04-01

While estimates of fossil fuel reserves and resources are very uncertain, and the amount which could ultimately be burnt under a business as usual scenario would depend on prevailing economic and technological conditions, an amount of five trillion tonnes of carbon (5 EgC), corresponding to the lower end of the range of estimates of the total fossil fuel resource, is often cited as an estimate of total cumulative emissions in the absence of mitigation actions. The IPCC Fifth Assessment Report indicates that an approximately linear relationship between warming and cumulative carbon emissions holds only up to around 2 EgC emissions. It is typically assumed that at higher cumulative emissions the warming would tend to be less than that predicted by such a linear relationship, with the radiative saturation effect dominating the effects of positive carbon-climate feedbacks at high emissions, as predicted by simple carbon-climate models. We analyze simulations from four state-of-the-art Earth System Models (ESMs) from the Coupled Model Intercomparison Project Phase 5 (CMIP5) and seven Earth System Models of Intermediate Complexity (EMICs), driven by the Representative Concentration Pathway 8.5 Extension scenario (RCP 8.5 Ext), which represents a very high emission scenario of increasing greenhouse gas concentrations in absence of climate mitigation policies. Our results demonstrate that while terrestrial and ocean carbon storage varies between the models, the CO2-induced warming continues to increase approximately linearly with cumulative carbon emissions even for higher levels of cumulative emissions, in all four ESMs. Five of the seven EMICs considered simulate a similarly linear response, while two exhibit less warming at higher cumulative emissions for reasons we discuss. The ESMs simulate global mean warming of 6.6-11.0°C, mean Arctic warming of 15.3-19.7°C, and mean regional precipitation increases and decreases by more than a factor of four, in response to 5Eg

Can warming particles enter global climate discussions?

International Nuclear Information System (INIS)

Bond, Tami C

2007-01-01

'Soot' or 'black carbon', which comes from incomplete combustion, absorbs light and warms the atmosphere. Although there have been repeated suggestions that reduction of black carbon could be a viable part of decreasing global warming, it has not yet been considered when choosing actions to reduce climatic impact. In this paper, I examine four conceptual barriers to the consideration of aerosols in global agreements. I conclude that some of the major objections to considering aerosols under hemispheric or global agreements are illusory because: (1) a few major sources will be addressed by local regulations, but the remainder may not be addressed by traditional air quality management; (2) climate forcing by carbon particles is not limited to 'hot spots'-about 90% of it occurs at relatively low concentrations; (3) while aerosol science is complex, the most salient characteristics of aerosol behavior can be condensed into tractable metrics including, but not limited to, the global warming potential; (4) despite scientific uncertainties, reducing all aerosols from major sources of black carbon will reduce direct climate warming with a very high probability. This change in climate forcing accounts for at least 25% of the accompanying CO 2 forcing with significant probability (25% for modern diesel engines, 90% for superemitting diesels, and 55% for cooking with biofuels). Thus, this fraction of radiative forcing should not be ignored

Incubation under Climate Warming Affects Behavioral Lateralisation in Port Jackson Sharks

Directory of Open Access Journals (Sweden)

Catarina Vila Pouca

2018-05-01

Full Text Available Climate change is warming the world’s oceans at an unprecedented rate. Under predicted end-of-century temperatures, many teleosts show impaired development and altered critical behaviors, including behavioral lateralisation. Since laterality is an expression of brain functional asymmetries, changes in the strength and direction of lateralisation suggest that rapid climate warming might impact brain development and function. However, despite the implications for cognitive functions, the potential effects of elevated temperature in lateralisation of elasmobranch fishes are unknown. We incubated and reared Port Jackson sharks at current and projected end-of-century temperatures and measured preferential detour responses to left or right. Sharks incubated at elevated temperature showed stronger absolute laterality and were significantly biased towards the right relative to sharks reared at current temperature. We propose that animals reared under elevated temperatures might have more strongly lateralized brains to cope with deleterious effects of climate change on brain development and growth. However, far more research in elasmobranch lateralisation is needed before the significance of these results can be fully comprehended. This study provides further evidence that elasmobranchs are susceptible to the effects of future ocean warming, though behavioral mechanisms might allow animals to compensate for some of the challenges imposed by climate change.

The long-term fate of permafrost peatlands under rapid climate warming

DEFF Research Database (Denmark)

Swindles, Graeme T.; Morris, Paul J.; Mullan, Donal

2015-01-01

Permafrost peatlands contain globally important amounts of soil organic carbon, owing to cold conditions which suppress anaerobic decomposition. However, climate warming and permafrost thaw threaten the stability of this carbon store. The ultimate fate of permafrost peatlands and their carbon...... stores is unclear because of complex feedbacks between peat accumulation, hydrology and vegetation. Field monitoring campaigns only span the last few decades and therefore provide an incomplete picture of permafrost peatland response to recent rapid warming. Here we use a high-resolution palaeoecological...... approach to understand the longer-term response of peatlands in contrasting states of permafrost degradation to recent rapid warming. At all sites we identify a drying trend until the late-twentieth century; however, two sites subsequently experienced a rapid shift to wetter conditions as permafrost thawed...

Evaluating the accuracy of climate change pattern emulation for low warming targets

Science.gov (United States)

Tebaldi, Claudia; Knutti, Reto

2018-05-01

Global climate policy is increasingly debating the value of very low warming targets, yet not many experiments conducted with global climate models in their fully coupled versions are currently available to help inform studies of the corresponding impacts. This raises the question whether a map of warming or precipitation change in a world 1.5 °C warmer than preindustrial can be emulated from existing simulations that reach higher warming targets, or whether entirely new simulations are required. Here we show that also for this type of low warming in strong mitigation scenarios, climate change signals are quite linear as a function of global temperature. Therefore, emulation techniques amounting to linear rescaling on the basis of global temperature change ratios (like simple pattern scaling) provide a viable way forward. The errors introduced are small relative to the spread in the forced response to a given scenario that we can assess from a multi-model ensemble. They are also small relative to the noise introduced into the estimates of the forced response by internal variability within a single model, which we can assess from either control simulations or initial condition ensembles. Challenges arise when scaling inadvertently reduces the inter-model spread or suppresses the internal variability, both important sources of uncertainty for impact assessment, or when the scenarios have very different characteristics in the composition of the forcings. Taking advantage of an available suite of coupled model simulations under low-warming and intermediate scenarios, we evaluate the accuracy of these emulation techniques and show that they are unlikely to represent a substantial contribution to the total uncertainty.

Leap frog in slow motion: Divergent responses of tree species and life stages to climatic warming in Great Basin subalpine forests

Science.gov (United States)

Brian V. Smithers; Malcolm P. North; Constance I. Millar; Andrew M. Latimer

2017-01-01

In response to climate warming, subalpine treelines are expected to move up in elevation since treelines are generally controlled by growing season temperature. Where treeline is advancing, dispersal differences and early life stage environmental tolerances are likely to affect how species expand their ranges. Species with an establishment advantage will...

Reductions in labour capacity from heat stress under climate warming

Science.gov (United States)

Dunne, John P.; Stouffer, Ronald J.; John, Jasmin G.

2013-06-01

A fundamental aspect of greenhouse-gas-induced warming is a global-scale increase in absolute humidity. Under continued warming, this response has been shown to pose increasingly severe limitations on human activity in tropical and mid-latitudes during peak months of heat stress. One heat-stress metric with broad occupational health applications is wet-bulb globe temperature. We combine wet-bulb globe temperatures from global climate historical reanalysis and Earth System Model (ESM2M) projections with industrial and military guidelines for an acclimated individual's occupational capacity to safely perform sustained labour under environmental heat stress (labour capacity)--here defined as a global population-weighted metric temporally fixed at the 2010 distribution. We estimate that environmental heat stress has reduced labour capacity to 90% in peak months over the past few decades. ESM2M projects labour capacity reduction to 80% in peak months by 2050. Under the highest scenario considered (Representative Concentration Pathway 8.5), ESM2M projects labour capacity reduction to less than 40% by 2200 in peak months, with most tropical and mid-latitudes experiencing extreme climatological heat stress. Uncertainties and caveats associated with these projections include climate sensitivity, climate warming patterns, CO2 emissions, future population distributions, and technological and societal change.

Global patterns in lake ecosystem responses to warming based on the temperature dependence of metabolism.

Science.gov (United States)

Kraemer, Benjamin M; Chandra, Sudeep; Dell, Anthony I; Dix, Margaret; Kuusisto, Esko; Livingstone, David M; Schladow, S Geoffrey; Silow, Eugene; Sitoki, Lewis M; Tamatamah, Rashid; McIntyre, Peter B

2017-05-01

Climate warming is expected to have large effects on ecosystems in part due to the temperature dependence of metabolism. The responses of metabolic rates to climate warming may be greatest in the tropics and at low elevations because mean temperatures are warmer there and metabolic rates respond exponentially to temperature (with exponents >1). However, if warming rates are sufficiently fast in higher latitude/elevation lakes, metabolic rate responses to warming may still be greater there even though metabolic rates respond exponentially to temperature. Thus, a wide range of global patterns in the magnitude of metabolic rate responses to warming could emerge depending on global patterns of temperature and warming rates. Here we use the Boltzmann-Arrhenius equation, published estimates of activation energy, and time series of temperature from 271 lakes to estimate long-term (1970-2010) changes in 64 metabolic processes in lakes. The estimated responses of metabolic processes to warming were usually greatest in tropical/low-elevation lakes even though surface temperatures in higher latitude/elevation lakes are warming faster. However, when the thermal sensitivity of a metabolic process is especially weak, higher latitude/elevation lakes had larger responses to warming in parallel with warming rates. Our results show that the sensitivity of a given response to temperature (as described by its activation energy) provides a simple heuristic for predicting whether tropical/low-elevation lakes will have larger or smaller metabolic responses to warming than higher latitude/elevation lakes. Overall, we conclude that the direct metabolic consequences of lake warming are likely to be felt most strongly at low latitudes and low elevations where metabolism-linked ecosystem services may be most affected. © 2016 John Wiley & Sons Ltd.

Responses of microbial biomass carbon and nitrogen to experimental warming: a meta-analysis

Science.gov (United States)

Xu, W.; Yuan, W.

2017-12-01

Soil microbes play important roles in regulating terrestrial carbon and nitrogen cycling and strongly influence feedbacks of ecosystem to global warming. However, the inconsistent responses of microbial biomass carbon (MBC) and nitrogen (MBN) to experimental warming have been observed, and the response on ratio between MBC and MBN (MBC:MBN) has not been identified. This meta-analysis synthesized the warming experiments at 58 sites globally to investigate the responses of MBC:MBN to climate warming. Our results showed that warming significantly increased MBC by 3.61 ± 0.80% and MBN by 5.85 ± 0.90% and thus decreased the MBC:MBN by 3.34 ± 0.66%. MBC showed positive responses to warming but MBN exhibited negative responses to warming at low warming magnitude (2°C) the results were inverted. The different effects of warming magnitude on microbial biomass resulted from the warming-induced decline in soil moisture and substrate supply. Moreover, MBC and MBN had strong positive responses to warming at the mid-term (3-4 years) or short-term (1-2 years) duration, but the responses tended to decrease at long-term (≥ 5 years) warming duration. This study fills the knowledge gap on the responses of MBC:MBN to warming and may benefit the development of coupled carbon and nitrogen models.

Seventh Grade Students' Conceptions of Global Warming and Climate Change

Science.gov (United States)

Shepardson, Daniel P.; Niyogi, Dev; Choi, Soyoung; Charusombat, Umarporn

2009-01-01

The purpose of this study was to investigate seventh grade students' conceptions of global warming and climate change. The study was descriptive in nature and involved the collection of qualitative data from 91 seventh grade students from three different schools in the Midwest, USA. An open response and draw and explain assessment instrument was…

Climate warming drives local extinction: Evidence from observation and experimentation.

Science.gov (United States)

Panetta, Anne Marie; Stanton, Maureen L; Harte, John

2018-02-01

Despite increasing concern about elevated extinction risk as global temperatures rise, it is difficult to confirm causal links between climate change and extinction. By coupling 25 years of in situ climate manipulation with experimental seed introductions and both historical and current plant surveys, we identify causal, mechanistic links between climate change and the local extinction of a widespread mountain plant ( Androsace septentrionalis ). Climate warming causes precipitous declines in population size by reducing fecundity and survival across multiple life stages. Climate warming also purges belowground seed banks, limiting the potential for the future recovery of at-risk populations under ameliorated conditions. Bolstered by previous reports of plant community shifts in this experiment and in other habitats, our findings not only support the hypothesis that climate change can drive local extinction but also foreshadow potentially widespread species losses in subalpine meadows as climate warming continues.

Climate change, irrigation, and Israeli agriculture. Will warming be harmful?

Energy Technology Data Exchange (ETDEWEB)

Fleischer, Aliza; Lichtman, Ivgenia [Hebrew University of Jerusalem, Jerusalem (Israel); Mendelsohn, Robert [Yale University, New Haven, Connecticut (United States)

2008-04-15

This paper utilizes a Ricardian model to test the relationship between annual net revenues and climate across Israeli farms. The study finds that it is important to include the amount of irrigation water available to each farm in order to measure the response of farms to climate. With irrigation water omitted, the model predicts climate change is strictly beneficial. However, with water included, the model predicts that only modest climate changes are beneficial while drastic climate change in the long run will be harmful. Using the AOGCM Scenarios we show that farm net revenue is expected to increase. Although Israel has a relatively warm climate a mild increase in temperature is beneficial due to the ability to supply international markets with farm product early in the season. (author)

Climate change, irrigation, and Israeli agriculture. Will warming be harmful?

International Nuclear Information System (INIS)

Fleischer, Aliza; Lichtman, Ivgenia; Mendelsohn, Robert

2008-01-01

This paper utilizes a Ricardian model to test the relationship between annual net revenues and climate across Israeli farms. The study finds that it is important to include the amount of irrigation water available to each farm in order to measure the response of farms to climate. With irrigation water omitted, the model predicts climate change is strictly beneficial. However, with water included, the model predicts that only modest climate changes are beneficial while drastic climate change in the long run will be harmful. Using the AOGCM Scenarios we show that farm net revenue is expected to increase. Although Israel has a relatively warm climate a mild increase in temperature is beneficial due to the ability to supply international markets with farm product early in the season. (author)

Climate warming drives local extinction: Evidence from observation and experimentation

Science.gov (United States)

Panetta, Anne Marie; Stanton, Maureen L.; Harte, John

2018-01-01

Despite increasing concern about elevated extinction risk as global temperatures rise, it is difficult to confirm causal links between climate change and extinction. By coupling 25 years of in situ climate manipulation with experimental seed introductions and both historical and current plant surveys, we identify causal, mechanistic links between climate change and the local extinction of a widespread mountain plant (Androsace septentrionalis). Climate warming causes precipitous declines in population size by reducing fecundity and survival across multiple life stages. Climate warming also purges belowground seed banks, limiting the potential for the future recovery of at-risk populations under ameliorated conditions. Bolstered by previous reports of plant community shifts in this experiment and in other habitats, our findings not only support the hypothesis that climate change can drive local extinction but also foreshadow potentially widespread species losses in subalpine meadows as climate warming continues. PMID:29507884

Climate change, global warming and coral reefs: modelling the effects of temperature.

Science.gov (United States)

Crabbe, M James C

2008-10-01

Climate change and global warming have severe consequences for the survival of scleractinian (reef-building) corals and their associated ecosystems. This review summarizes recent literature on the influence of temperature on coral growth, coral bleaching, and modelling the effects of high temperature on corals. Satellite-based sea surface temperature (SST) and coral bleaching information available on the internet is an important tool in monitoring and modelling coral responses to temperature. Within the narrow temperature range for coral growth, corals can respond to rate of temperature change as well as to temperature per se. We need to continue to develop models of how non-steady-state processes such as global warming and climate change will affect coral reefs.

Does Climate Literacy Matter? A Case Study of U.S. Students' Level of Concern about Anthropogenic Global Warming

Science.gov (United States)

Bedford, Daniel

2016-01-01

Educators seeking to address global warming in their classrooms face numerous challenges, including the question of whether student opinions about anthropogenic global warming (AGW) can change in response to increased knowledge about the climate system. This article analyzes survey responses from 458 students at a primarily undergraduate…

Plants, birds and butterflies: short-term responses of species communities to climate warming vary by taxon and with altitude.

Science.gov (United States)

Roth, Tobias; Plattner, Matthias; Amrhein, Valentin

2014-01-01

As a consequence of climate warming, species usually shift their distribution towards higher latitudes or altitudes. Yet, it is unclear how different taxonomic groups may respond to climate warming over larger altitudinal ranges. Here, we used data from the national biodiversity monitoring program of Switzerland, collected over an altitudinal range of 2500 m. Within the short period of eight years (2003-2010), we found significant shifts in communities of vascular plants, butterflies and birds. At low altitudes, communities of all species groups changed towards warm-dwelling species, corresponding to an average uphill shift of 8 m, 38 m and 42 m in plant, butterfly and bird communities, respectively. However, rates of community changes decreased with altitude in plants and butterflies, while bird communities changed towards warm-dwelling species at all altitudes. We found no decrease in community variation with respect to temperature niches of species, suggesting that climate warming has not led to more homogenous communities. The different community changes depending on altitude could not be explained by different changes of air temperatures, since during the 16 years between 1995 and 2010, summer temperatures in Switzerland rose by about 0.07°C per year at all altitudes. We discuss that land-use changes or increased disturbances may have prevented alpine plant and butterfly communities from changing towards warm-dwelling species. However, the findings are also consistent with the hypothesis that unlike birds, many alpine plant species in a warming climate could find suitable habitats within just a few metres, due to the highly varied surface of alpine landscapes. Our results may thus support the idea that for plants and butterflies and on a short temporal scale, alpine landscapes are safer places than lowlands in a warming world.

Insolation driven biomagnetic response to Holocene Warm Period in semi-arid East Asia

OpenAIRE

Liu, S.; Deng, Chenglong; Xiao, Jule; Li, Jinhua; Paterson, Greig; Chang, Liao; Yi, Liang; Qin, Huafeng; Pan, Yongxin; Zhu, Rixiang

2015-01-01

The Holocene Warm Period (HWP) provides valuable insights into the climate system and biotic responses to environmental variability and thus serves as an excellent analogue for future global climate changes. Here we document, for the first time, that warm and wet HWP conditions were highly favourable for magnetofossil proliferation in the semi-arid Asian interior. The pronounced increase of magnetofossil concentrations at ~9.8 ka and decrease at ~5.9 ka in Dali Lake coincided respectively wit...

El Nino/Southern Oscillation response to global warming.

Science.gov (United States)

Latif, M; Keenlyside, N S

2009-12-08

The El Niño/Southern Oscillation (ENSO) phenomenon, originating in the Tropical Pacific, is the strongest natural interannual climate signal and has widespread effects on the global climate system and the ecology of the Tropical Pacific. Any strong change in ENSO statistics will therefore have serious climatic and ecological consequences. Most global climate models do simulate ENSO, although large biases exist with respect to its characteristics. The ENSO response to global warming differs strongly from model to model and is thus highly uncertain. Some models simulate an increase in ENSO amplitude, others a decrease, and others virtually no change. Extremely strong changes constituting tipping point behavior are not simulated by any of the models. Nevertheless, some interesting changes in ENSO dynamics can be inferred from observations and model integrations. Although no tipping point behavior is envisaged in the physical climate system, smooth transitions in it may give rise to tipping point behavior in the biological, chemical, and even socioeconomic systems. For example, the simulated weakening of the Pacific zonal sea surface temperature gradient in the Hadley Centre model (with dynamic vegetation included) caused rapid Amazon forest die-back in the mid-twenty-first century, which in turn drove a nonlinear increase in atmospheric CO(2), accelerating global warming.

Contrasting growth responses of dominant peatland plants to warming and vegetation composition.

Science.gov (United States)

Walker, Tom N; Ward, Susan E; Ostle, Nicholas J; Bardgett, Richard D

2015-05-01

There is growing recognition that changes in vegetation composition can strongly influence peatland carbon cycling, with potential feedbacks to future climate. Nevertheless, despite accelerated climate and vegetation change in this ecosystem, the growth responses of peatland plant species to combined warming and vegetation change are unknown. Here, we used a field warming and vegetation removal experiment to test the hypothesis that dominant species from the three plant functional types present (dwarf-shrubs: Calluna vulgaris; graminoids: Eriophorum vaginatum; bryophytes: Sphagnum capillifolium) contrast in their growth responses to warming and the presence or absence of other plant functional types. Warming was accomplished using open top chambers, which raised air temperature by approximately 0.35 °C, and we measured air and soil microclimate as potential mechanisms through which both experimental factors could influence growth. We found that only Calluna growth increased with experimental warming (by 20%), whereas the presence of dwarf-shrubs and bryophytes increased growth of Sphagnum (46%) and Eriophorum (20%), respectively. Sphagnum growth was also negatively related to soil temperature, which was lower when dwarf-shrubs were present. Dwarf-shrubs may therefore promote Sphagnum growth by cooling the peat surface. Conversely, the effect of bryophyte presence on Eriophorum growth was not related to any change in microclimate, suggesting other factors play a role. In conclusion, our findings reveal contrasting abiotic and biotic controls over dominant peatland plant growth, suggesting that community composition and carbon cycling could be modified by simultaneous climate and vegetation change.

Effects of in situ climate warming on monarch caterpillar (Danaus plexippus development

Directory of Open Access Journals (Sweden)

Nathan P. Lemoine

2015-10-01

Full Text Available Climate warming will fundamentally alter basic life history strategies of many ectothermic insects. In the lab, rising temperatures increase growth rates of lepidopteran larvae but also reduce final pupal mass and increase mortality. Using in situ field warming experiments on their natural host plants, we assessed the impact of climate warming on development of monarch (Danaus plexippus larvae. Monarchs were reared on Asclepias tuberosa grown under ‘Ambient’ and ‘Warmed’ conditions. We quantified time to pupation, final pupal mass, and survivorship. Warming significantly decreased time to pupation, such that an increase of 1 °C corresponded to a 0.5 day decrease in pupation time. In contrast, survivorship and pupal mass were not affected by warming. Our results indicate that climate warming will speed the developmental rate of monarchs, influencing their ecological and evolutionary dynamics. However, the effects of climate warming on larval development in other monarch populations and at different times of year should be investigated.

Why tropical forest lizards are vulnerable to climate warming

Science.gov (United States)

Huey, Raymond B.; Deutsch, Curtis A.; Tewksbury, Joshua J.; Vitt, Laurie J.; Hertz, Paul E.; Álvarez Pérez, Héctor J.; Garland, Theodore

2009-01-01

Biological impacts of climate warming are predicted to increase with latitude, paralleling increases in warming. However, the magnitude of impacts depends not only on the degree of warming but also on the number of species at risk, their physiological sensitivity to warming and their options for behavioural and physiological compensation. Lizards are useful for evaluating risks of warming because their thermal biology is well studied. We conducted macrophysiological analyses of diurnal lizards from diverse latitudes plus focal species analyses of Puerto Rican Anolis and Sphaerodactyus. Although tropical lowland lizards live in environments that are warm all year, macrophysiological analyses indicate that some tropical lineages (thermoconformers that live in forests) are active at low body temperature and are intolerant of warm temperatures. Focal species analyses show that some tropical forest lizards were already experiencing stressful body temperatures in summer when studied several decades ago. Simulations suggest that warming will not only further depress their physiological performance in summer, but will also enable warm-adapted, open-habitat competitors and predators to invade forests. Forest lizards are key components of tropical ecosystems, but appear vulnerable to the cascading physiological and ecological effects of climate warming, even though rates of tropical warming may be relatively low. PMID:19324762

Short term response of a peatland to warming and drought - climate manipulation experiment in W Poland

Science.gov (United States)

Juszczak, Radosław; Chojnicki, Bogdan; Urbaniak, Marek; Leśny, Jacek; Silvennoinen, Hanna; Lamentowicz, Mariusz; Basińska, Anna; Gąbka, Maciej; Stróżecki, Marcin; Samson, Mateusz; Łuców, Dominika; Józefczyk, Damian; Hoffmann, Mathias; Olejnik, Janusz

2016-04-01

conditions led to increases in NDVI and LAI, whilst the site exposed to only drought exhibited the lowest LAI. Warming shifted the vegetation species composition by promoting vascular plants (mainly Carex rostrata and C. limosa), which result also correlates positively with nutrient (Ptot, Mn, F, Na, Zn) availability in the peat water. Here, we report short-term responses to increased temperature and diminished precipitation, showing that the combination of these to stressors leads to very different scenario than their individual impacts. Our results further emphasize the need for long term records from field manipulation site on peatland response to climate changes. The Research was co-founded by the Polish National Centre for Research and Development within the Polish-Norwegian Research Programme within the WETMAN project (Central European Wetland Ecosystem Feedbacks to Changing Climate - Field Scale Manipulation, Project ID: 203258, contract No. Pol-Nor/203258/31/2013 (www.wetman.pl). References Fenner N., Freeman Ch. (2011). Nature Geoscience, 4, 895-900 Hoffmann M., et al. (2015). Agricultural and Forest Meteorology, 200, 30-45 Kimball BA. (2005). Global Change Biology, 11, 2041-2056

Initial response of the nitrogen cycle to soil warming in Northern Minnesota peatlands

Science.gov (United States)

Peatlands store 30% of global soil carbon. Many of these peatlands are located in boreal regions which are expected to have the highest temperature increases in response to climate change. As climate warms, peat decomposition may accelerate and release greenhouse gases. Spruce a...

Indian Ocean warming modulates Pacific climate change

Science.gov (United States)

Luo, Jing-Jia; Sasaki, Wataru; Masumoto, Yukio

2012-01-01

It has been widely believed that the tropical Pacific trade winds weakened in the last century and would further decrease under a warmer climate in the 21st century. Recent high-quality observations, however, suggest that the tropical Pacific winds have actually strengthened in the past two decades. Precise causes of the recent Pacific climate shift are uncertain. Here we explore how the enhanced tropical Indian Ocean warming in recent decades favors stronger trade winds in the western Pacific via the atmosphere and hence is likely to have contributed to the La Niña-like state (with enhanced east–west Walker circulation) through the Pacific ocean–atmosphere interactions. Further analysis, based on 163 climate model simulations with centennial historical and projected external radiative forcing, suggests that the Indian Ocean warming relative to the Pacific’s could play an important role in modulating the Pacific climate changes in the 20th and 21st centuries. PMID:23112174

Indian Ocean warming modulates Pacific climate change.

Science.gov (United States)

Luo, Jing-Jia; Sasaki, Wataru; Masumoto, Yukio

2012-11-13

It has been widely believed that the tropical Pacific trade winds weakened in the last century and would further decrease under a warmer climate in the 21st century. Recent high-quality observations, however, suggest that the tropical Pacific winds have actually strengthened in the past two decades. Precise causes of the recent Pacific climate shift are uncertain. Here we explore how the enhanced tropical Indian Ocean warming in recent decades favors stronger trade winds in the western Pacific via the atmosphere and hence is likely to have contributed to the La Niña-like state (with enhanced east-west Walker circulation) through the Pacific ocean-atmosphere interactions. Further analysis, based on 163 climate model simulations with centennial historical and projected external radiative forcing, suggests that the Indian Ocean warming relative to the Pacific's could play an important role in modulating the Pacific climate changes in the 20th and 21st centuries.

Tuning the climate sensitivity of a global model to match 20th Century warming

Science.gov (United States)

Mauritsen, T.; Roeckner, E.

2015-12-01

A climate models ability to reproduce observed historical warming is sometimes viewed as a measure of quality. Yet, for practical reasons historical warming cannot be considered a purely empirical result of the modelling efforts because the desired result is known in advance and so is a potential target of tuning. Here we explain how the latest edition of the Max Planck Institute for Meteorology Earth System Model (MPI-ESM1.2) atmospheric model (ECHAM6.3) had its climate sensitivity systematically tuned to about 3 K; the MPI model to be used during CMIP6. This was deliberately done in order to improve the match to observed 20th Century warming over the previous model generation (MPI-ESM, ECHAM6.1) which warmed too much and had a sensitivity of 3.5 K. In the process we identified several controls on model cloud feedback that confirm recently proposed hypotheses concerning trade-wind cumulus and high-latitude mixed-phase clouds. We then evaluate the model fidelity with centennial global warming and discuss the relative importance of climate sensitivity, forcing and ocean heat uptake efficiency in determining the response as well as possible systematic biases. The activity of targeting historical warming during model development is polarizing the modeling community with 35 percent of modelers stating that 20th Century warming was rated very important to decisive, whereas 30 percent would not consider it at all. Likewise, opinions diverge as to which measures are legitimate means for improving the model match to observed warming. These results are from a survey conducted in conjunction with the first WCRP Workshop on Model Tuning in fall 2014 answered by 23 modelers. We argue that tuning or constructing models to match observed warming to some extent is practically unavoidable, and as such, in many cases might as well be done explicitly. For modeling groups that have the capability to tune both their aerosol forcing and climate sensitivity there is now a unique

Physiological effects of climate warming on flowering plants and insect pollinators and potential consequences for their interactions

Directory of Open Access Journals (Sweden)

Victoria L. SCAVEN, Nicole E. RAFFERTY

2013-06-01

Full Text Available Growing concern about the influence of climate change on flowering plants, pollinators, and the mutualistic interactions between them has led to a recent surge in research. Much of this research has addressed the consequences of warming for phenological and distributional shifts. In contrast, relatively little is known about the physiological responses of plants and insect pollinators to climate warming and, in particular, how these responses might affect plant-pollinator interactions. Here, we summarize the direct physiological effects of temperature on flowering plants and pollinating insects to highlight ways in which plant and pollinator responses could affect floral resources for pollinators, and pollination success for plants, respectively. We also consider the overall effects of these responses on plant-pollinator interaction networks. Plant responses to warming, which include altered flower, nectar, and pollen production, could modify floral resource availability and reproductive output of pollinating insects. Similarly, pollinator responses, such as altered foraging activity, body size, and life span, could affect patterns of pollen flow and pollination success of flowering plants. As a result, network structure could be altered as interactions are gained and lost, weakened and strengthened, even without the gain or loss of species or temporal overlap. Future research that addresses not only how plant and pollinator physiology are affected by warming but also how responses scale up to affect interactions and networks should allow us to better understand and predict the effects of climate change on this important ecosystem service [Current Zoolo­gy 59 (3: 418–426, 2013].

Combining observations and models to reduce uncertainty in the cloud response to global warming

Science.gov (United States)

Norris, J. R.; Myers, T.; Chellappan, S.

2017-12-01

Currently there is large uncertainty on how subtropical low-level clouds will respond to global warming and whether they will act as a positive feedback or negative feedback. Global climate models substantially agree on what changes in atmospheric structure and circulation will occur with global warming but greatly disagree over how clouds will respond to these changes in structure and circulation. An examination of models with the most realistic simulations of low-level cloudiness indicates that the model cloud response to atmospheric changes associated with global warming is quantitatively similar to the model cloud response to atmospheric changes at interannual time scales. For these models, the cloud response to global warming predicted by multilinear regression using coefficients derived from interannual time scales is quantitatively similar to the cloud response to global warming directly simulated by the model. Since there is a large spread among cloud response coefficients even among models with the most realistic cloud simulations, substitution of coefficients derived from satellite observations reduces the uncertainty range of the low-level cloud feedback. Increased sea surface temperature associated with global warming acts to reduce low-level cloudiness, which is partially offset by increased lower tropospheric stratification that acts to enhance low-level cloudiness. Changes in free-tropospheric relative humidity, subsidence, and horizontal advection have only a small impact on low-level cloud. The net reduction in subtropical low-level cloudiness increases absorption of solar radiation by the climate system, thus resulting in a weak positive feedback.

Climate Warming Can Increase Soil Carbon Fluxes Without Decreasing Soil Carbon Stocks in Boreal Forests

Science.gov (United States)

Ziegler, S. E.; Benner, R. H.; Billings, S. A.; Edwards, K. A.; Philben, M. J.; Zhu, X.; Laganiere, J.

2016-12-01

Ecosystem C fluxes respond positively to climate warming, however, the net impact of changing C fluxes on soil organic carbon (SOC) stocks over decadal scales remains unclear. Manipulative studies and global-scale observations have informed much of the existing knowledge of SOC responses to climate, providing insights on relatively short (e.g. days to years) and long (centuries to millennia) time scales, respectively. Natural climate gradient studies capture integrated ecosystem responses to climate on decadal time scales. Here we report the soil C reservoirs, fluxes into and out of those reservoirs, and the chemical composition of inputs and soil organic matter pools along a mesic boreal forest climate transect. The sites studied consist of similar forest composition, successional stage, and soil moisture but differ by 5.2°C mean annual temperature. Carbon fluxes through these boreal forest soils were greatest in the lowest latitude regions and indicate that enhanced C inputs can offset soil C losses with warming in these forests. Respiration rates increased by 55% and the flux of dissolved organic carbon from the organic to mineral soil horizons tripled across this climate gradient. The 2-fold increase in litterfall inputs to these soils coincided with a significant increase in the organic horizon C stock with warming, however, no significant difference in the surface mineral soil C stocks was observed. The younger mean age of the mineral soil C ( 70 versus 330 YBP) provided further evidence for the greater turnover of SOC in the warmer climate soils. In spite of these differences in mean radiocarbon age, mineral SOC exhibited chemical characteristics of highly decomposed material across all regions. In contrast with depth trends in soil OM diagenetic indices, diagenetic shifts with latitude were limited to increases in C:N and alkyl to O-alkyl ratios in the overlying organic horizons in the warmer relative to the colder regions. These data indicate that the

Deep time evidence for climate sensitivity increase with warming

DEFF Research Database (Denmark)

Shaffer, Gary; Huber, Matthew; Rondanelli, Roberto

2016-01-01

warming analogue. We obtain constrained estimates of CO2 and climate sensitivity before and during the PETM and of the PETM carbon input amount and nature. Sensitivity increased from 3.3-5.6 to 3.7-6.5K (Kelvin) into the PETM. When taken together with Last Glacial Maximum and modern estimates, this result...... world, but past warming events may provide insight. Here we employ paleoreconstructions and new climate-carbon model simulations in a novel framework to explore a wide scenario range for the Paleocene-Eocene Thermal Maximum (PETM) carbon release and global warming event 55.8Ma ago, a possible future...

Impacts of climate extremes on gross primary production under global warming

International Nuclear Information System (INIS)

Williams, I N; Torn, M S; Riley, W J; Wehner, M F

2014-01-01

The impacts of historical droughts and heat-waves on ecosystems are often considered indicative of future global warming impacts, under the assumption that water stress sets in above a fixed high temperature threshold. Historical and future (RCP8.5) Earth system model (ESM) climate projections were analyzed in this study to illustrate changes in the temperatures for onset of water stress under global warming. The ESMs examined here predict sharp declines in gross primary production (GPP) at warm temperature extremes in historical climates, similar to the observed correlations between GPP and temperature during historical heat-waves and droughts. However, soil moisture increases at the warm end of the temperature range, and the temperature at which soil moisture declines with temperature shifts to a higher temperature. The temperature for onset of water stress thus increases under global warming and is associated with a shift in the temperature for maximum GPP to warmer temperatures. Despite the shift in this local temperature optimum, the impacts of warm extremes on GPP are approximately invariant when extremes are defined relative to the optimal temperature within each climate period. The GPP sensitivity to these relative temperature extremes therefore remains similar between future and present climates, suggesting that the heat- and drought-induced GPP reductions seen recently can be expected to be similar in the future, and may be underestimates of future impacts given model projections of increased frequency and persistence of heat-waves and droughts. The local temperature optimum can be understood as the temperature at which the combination of water stress and light limitations is minimized, and this concept gives insights into how GPP responds to climate extremes in both historical and future climate periods. Both cold (temperature and light-limited) and warm (water-limited) relative temperature extremes become more persistent in future climate projections

Twentieth century North Atlantic climate change. Part II: Understanding the effect of Indian Ocean warming

Energy Technology Data Exchange (ETDEWEB)

Hoerling, M.P.; Xu, T.; Bates, G.T. [Climate Diagnostics Center NOAA, Boulder, CO 80305-3328 (United States); Hurrell, J.W.; Phillips, A.S. [National Center for Atmospheric Research, Boulder, CO (United States)

2004-09-01

Ensembles of atmospheric general circulation model (AGCM) experiments are used in an effort to understand the boreal winter Northern Hemisphere (NH) extratropical climate response to the observed warming of tropical sea surface temperatures (SSTs) over the last half of the twentieth Century. Specifically, we inquire about the origins of unusual, if not unprecedented, changes in the wintertime North Atlantic and European climate that are well described by a linear trend in most indices of the North Atlantic Oscillation (NAO). The simulated NH atmospheric response to the linear trend component of tropic-wide SST change since 1950 projects strongly onto the positive polarity of the NAO and is a hemispheric pattern distinguished by decreased (increased) Arctic (middle latitude) sea level pressure. Progressive warming of the Indian Ocean is the principal contributor to this wintertime extratropical response, as shown through additional AGCM ensembles forced with only the SST trend in that sector. The Indian Ocean influence is further established through the reproducibility of results across three different models forced with identical, idealized patterns of the observed warming. Examination of the transient atmospheric adjustment to a sudden ''switch-on'' of an Indian Ocean SST anomaly reveals that the North Atlantic response is not consistent with linear theory and most likely involves synoptic eddy feedbacks associated with changes in the North Atlantic storm track. The tropical SST control exerted over twentieth century regional climate underlies the importance of determining the future course of tropical SST for regional climate change and its uncertainty. Better understanding of the extratropical responses to different, plausible trajectories of the tropical oceans is key to such efforts. (orig.)

Global warming-setting the stages

International Nuclear Information System (INIS)

1994-01-01

Most of us have heard or read about global warming. However, the messages we receive are often in conflict, raising more questions than answer. Is global warming a good or a bad thing? has it already started or is it part of our future? Are we, or are we not doing anything about it? Should we be concerned? This primer on Global Warming is designed to clear up some of this confusion by providing basic scientific information on global warming issue. It is clear that there is still much to learn about global warming. However, it is also clear that there is a lot that we already know - and that dose provide cause for concern. We must understand the global warming issue if we are to make wise decisions and take responsible actions in response to the challenges and opportunities posed by global warming. Chapter 1 of 'the primer on global Warming' set the stage with a brief overview of science of global warming within the context of climate change. In addition, it introduces the specific issues that surround the global warming problem. As far as the science of global warming is concerned the following questions are discussed. What is global climate? Is climate change natural? What causes climate to vary on a global scale? How does the composition of the atmosphere relate to climate change. but there are also certain issues discussed here which surround the global warming such as: If climate varies naturally, why is there a concern about 'global warming'? What are the potential consequences of 'global warning'. What human activities contribute to 'global warming'. (Author)

Insolation driven biomagnetic response to the Holocene Warm Period in semi-arid East Asia

OpenAIRE

Liu, Suzhen; Deng, Chenglong; Xiao, Jule; Li, Jinhua; Paterson, Greig A.; Chang, Liao; Yi, Liang; Qin, Huafeng; Pan, Yongxin; Zhu, Rixiang

2015-01-01

The Holocene Warm Period (HWP) provides valuable insights into the climate system and biotic responses to environmental variability and thus serves as an excellent analogue for future global climate changes. Here we document, for the first time, that warm and wet HWP conditions were highly favourable for magnetofossil proliferation in the semi-arid Asian interior. The pronounced increase of magnetofossil concentrations at ~9.8?ka and decrease at ~5.9?ka in Dali Lake coincided respectively wit...

Ecosystem responses to warming and watering in typical and desert steppes

Science.gov (United States)

Xu, Zhenzhu; Hou, Yanhui; Zhang, Lihua; Liu, Tao; Zhou, Guangsheng

2016-10-01

Global warming is projected to continue, leading to intense fluctuations in precipitation and heat waves and thereby affecting the productivity and the relevant biological processes of grassland ecosystems. Here, we determined the functional responses to warming and altered precipitation in both typical and desert steppes. The results showed that watering markedly increased the aboveground net primary productivity (ANPP) in a typical steppe during a drier year and in a desert steppe over two years, whereas warming manipulation had no significant effect. The soil microbial biomass carbon (MBC) and the soil respiration (SR) were increased by watering in both steppes, but the SR was significantly decreased by warming in the desert steppe only. The inorganic nitrogen components varied irregularly, with generally lower levels in the desert steppe. The belowground traits of soil total organic carbon (TOC) and the MBC were more closely associated with the ANPP in the desert than in the typical steppes. The results showed that the desert steppe with lower productivity may respond strongly to precipitation changes, particularly with warming, highlighting the positive effect of adding water with warming. Our study implies that the habitat- and year-specific responses to warming and watering should be considered when predicting an ecosystem’s functional responses under climate change scenarios.

A farm-level analysis of economic and agronomic impacts of gradual climate warming

International Nuclear Information System (INIS)

Kaiser, H.M.; Sampath, R.; Riha, S.J.; Wilks, D.S.; Rossiter, D.G.

1993-01-01

The potential economic and agronomic impacts of gradual climate warming are examined at the farm level. Three models of the relevant climatic, agronomic, and economic processes are developed and linked to address climate change impacts and agricultural adaptability. Several climate warming severity. The results indicate that grain farmers in southern Minnesota can effectively adapt to a gradually changing climate (warmer and either wetter or drier) by adopting later maturing cultivars, changing crop mix, and altering the timing of field operations to take advantage of a longer growing season resulting from climate warming

Climatic irregular staircases: generalized acceleration of global warming.

Science.gov (United States)

De Saedeleer, Bernard

2016-01-27

Global warming rates mentioned in the literature are often restricted to a couple of arbitrary periods of time, or of isolated values of the starting year, lacking a global view. In this study, we perform on the contrary an exhaustive parametric analysis of the NASA GISS LOTI data, and also of the HadCRUT4 data. The starting year systematically varies between 1880 and 2002, and the averaging period from 5 to 30 yr - not only decades; the ending year also varies . In this way, we uncover a whole unexplored space of values for the global warming rate, and access the full picture. Additionally, stairstep averaging and linear least squares fitting to determine climatic trends have been sofar exclusive. We propose here an original hybrid method which combines both approaches in order to derive a new type of climatic trend. We find that there is an overall acceleration of the global warming whatever the value of the averaging period, and that 99.9% of the 3029 Earth's climatic irregular staircases are rising. Graphical evidence is also given that choosing an El Niño year as starting year gives lower global warming rates - except if there is a volcanic cooling in parallel. Our rates agree and generalize several results mentioned in the literature.

Climate variability slows evolutionary responses of Colias butterflies to recent climate change.

Science.gov (United States)

Kingsolver, Joel G; Buckley, Lauren B

2015-03-07

How does recent climate warming and climate variability alter fitness, phenotypic selection and evolution in natural populations? We combine biophysical, demographic and evolutionary models with recent climate data to address this question for the subalpine and alpine butterfly, Colias meadii, in the southern Rocky Mountains. We focus on predicting patterns of selection and evolution for a key thermoregulatory trait, melanin (solar absorptivity) on the posterior ventral hindwings, which affects patterns of body temperature, flight activity, adult and egg survival, and reproductive success in Colias. Both mean annual summer temperatures and thermal variability within summers have increased during the past 60 years at subalpine and alpine sites. At the subalpine site, predicted directional selection on wing absorptivity has shifted from generally positive (favouring increased wing melanin) to generally negative during the past 60 years, but there is substantial variation among years in the predicted magnitude and direction of selection and the optimal absorptivity. The predicted magnitude of directional selection at the alpine site declined during the past 60 years and varies substantially among years, but selection has generally been positive at this site. Predicted evolutionary responses to mean climate warming at the subalpine site since 1980 is small, because of the variability in selection and asymmetry of the fitness function. At both sites, the predicted effects of adaptive evolution on mean population fitness are much smaller than the fluctuations in mean fitness due to climate variability among years. Our analyses suggest that variation in climate within and among years may strongly limit evolutionary responses of ectotherms to mean climate warming in these habitats. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Forest Plant community changes during 1989-2007 in response to climate warming in the Jura Mountains (France and Switzerland)

DEFF Research Database (Denmark)

Lenoir, Jonathan; Gégout, J.C.; Dupouey, J.L.

2010-01-01

Question: How strong are climate warming-driven changes within mid-elevation forest communities? Observations of plant community change within temperate mountain forest ecosystems in response to recent warming are scarce in comparison to high-elevation alpine and nival ecosystems, perhaps...... reflecting the confounding influence of forest stand dynamics. Location: Jura Mountains (France and Switzerland). Methods: We assessed changes in plant community composition by surveying 154 Abies alba forest vegetation relevés (550-1,350 m a.s.l.) in 1989 and 2007. Over this period, temperatures increased...... while precipitation did not change. Correspondence analysis (CA) and ecological indicator values were used to measure changes in plant community composition. Relevés in even- and uneven-aged stands were analysed separately to determine the influence of forest stand dynamics. We also analysed changes...

Climate warming: what we can actually expect

International Nuclear Information System (INIS)

Delbecq, Denis; Lemarchand, Fabienne; Boucher, Olivier; Dessus, Benjamin; Laponche, Bernard; Le Treut, Herve

2013-01-01

As the next IPCC (Intergovernmental Panel on Climate Change) report is soon to be published, a paleo-climatologist answers few questions about issues related to climate change (recent climate events, slower temperature increase during the past ten years, lessons learned from the previous IPCC report, evolutions of models, remaining opportunities to limit temperature increase to 2 degrees). A second article comments climate modelling improvements (finer description of oceans, atmosphere and ice field, introduction of new mechanisms in IPCC models such as carbon cycle, vegetation evolution, aerosols and atmospheric chemistry, models relying on greenhouse gas emission principles and not on socioeconomic scenarios any longer). A third article outlines that Earth has never been so warm since 1850 and proposes some explanations about the fact that warming has slowed down during the last ten years. A fourth article discusses how greenhouse gas emissions can be reduced, notices that their accounting underestimates the short-term and medium-term impact of methane emission reduction, and stresses the importance of an increased attention to methane emissions

GLOBAL WARMING, CLIMATE CHANGE AND TOURISM: A REVIEW OF LITERATURE

OpenAIRE

Ramasamy, Rajesh; Swamy, Anjaneya

2015-01-01

Global warming, climate change and tourism of late, have taken the centre stage of academic research. A raging debate is on apart from the popular writings and research articles published on the theme. According to the Intergovernmental Panel on Climate Change “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 since the mid 20th century”. This conceptual paper discussed...

Developing a module for estimating climate warming effects on hydropower pricing in California

International Nuclear Information System (INIS)

Guégan, Marion; Uvo, Cintia B.; Madani, Kaveh

2012-01-01

Climate warming is expected to alter hydropower generation in California through affecting the annual stream-flow regimes and reducing snowpack. On the other hand, increased temperatures are expected to increase hydropower demand for cooling in warm periods while decreasing demand for heating in winter, subsequently altering the annual hydropower pricing patterns. The resulting variations in hydropower supply and pricing regimes necessitate changes in reservoir operations to minimize the revenue losses from climate warming. Previous studies in California have only explored the effects of hydrological changes on hydropower generation and revenues. This study builds a long-term hydropower pricing estimation tool, based on artificial neural network (ANN), to develop pricing scenarios under different climate warming scenarios. Results suggest higher average hydropower prices under climate warming scenarios than under historical climate. The developed tool is integrated with California's Energy-Based Hydropower Optimization Model (EBHOM) to facilitate simultaneous consideration of climate warming on hydropower supply, demand and pricing. EBHOM estimates an additional 5% drop in annual revenues under a dry warming scenario when climate change impacts on pricing are considered, with respect to when such effects are ignored, underlining the importance of considering changes in hydropower demand and pricing in future studies and policy making. - Highlights: ► Addressing the major gap in previous climate change and hydropower studies in California. ► Developing an ANN-based long-term hydropower price estimation tool. ► Estimating climate change effects on hydropower demand and pricing in California. ► Investigating the sensitivity of hydropower operations to future price changes. ► Underlining the importance of consideration of climate change impacts on electricity pricing.

A Robust Response of Precipitation to Global Warming from CMIP5 Models

Science.gov (United States)

Lau, K. -M.; Wu, H. -T.; Kim, K. -M.

2012-01-01

How precipitation responds to global warming is a major concern to society and a challenge to climate change research. Based on analyses of rainfall probability distribution functions of 14 state-of-the-art climate models, we find a robust, canonical global rainfall response to a triple CO2 warming scenario, featuring 100 250% more heavy rain, 5-10% less moderate rain, and 10-15% more very light or no-rain events. Regionally, a majority of the models project a consistent response with more heavy rain events over climatologically wet regions of the deep tropics, and more dry events over subtropical and tropical land areas. Results suggest that increased CO2 emissions induce basic structural changes in global rain systems, increasing risks of severe floods and droughts in preferred geographic locations worldwide.

Long-term ecophysiological responses to climate change

DEFF Research Database (Denmark)

Boesgaard, Kristine Stove; Ro-Poulsen, Helge

Plant physiology is affected by climate change. Acclimations of photosynthetic processes are induced by short-term changes in climatic conditions. Further acclimation can be caused by longterm adjustments to climate change due to ecosystem-feedbacks. The aim of this PhD was to investigate plant...... term responses of plant physiology to the climate change factors were investigated. In the CLIMAITE-experiment it has been shown that 2 years of treatment altered physiological responses in Deschampsiaand Calluna. In the work of this PhD similar responses were observed after 6 years of treatment...... physiological responses to climate change in a seasonal and long-term perspective. The effects of elevated CO2, passive night time warming and periodic summer drought as single factor and in combination, on plant physiology were investigated in the long-term multifactorial field experiment CLIMAITE in a Danish...

Biomass production in experimental grasslands of different species richness during three years of climate warming

Science.gov (United States)

de Boeck, H. J.; Lemmens, C. M. H. M.; Zavalloni, C.; Gielen, B.; Malchair, S.; Carnol, M.; Merckx, R.; van den Berge, J.; Ceulemans, R.; Nijs, I.

2008-04-01

Here we report on the single and combined impacts of climate warming and species richness on the biomass production in experimental grassland communities. Projections of a future warmer climate have stimulated studies on the response of terrestrial ecosystems to this global change. Experiments have likewise addressed the importance of species numbers for ecosystem functioning. There is, however, little knowledge on the interplay between warming and species richness. During three years, we grew experimental plant communities containing one, three or nine grassland species in 12 sunlit, climate-controlled chambers in Wilrijk, Belgium. Half of these chambers were exposed to ambient air temperatures (unheated), while the other half were warmed by 3°C (heated). Equal amounts of water were added to heated and unheated communities, so that warming would imply drier soils if evapotranspiration was higher. Biomass production was decreased due to warming, both aboveground (-29%) and belowground (-25%), as negative impacts of increased heat and drought stress in summer prevailed. Complementarity effects, likely mostly through both increased aboveground spatial complementarity and facilitative effects of legumes, led to higher shoot and root biomass in multi-species communities, regardless of the induced warming. Surprisingly, warming suppressed productivity the most in 9-species communities, which may be attributed to negative impacts of intense interspecific competition for resources under conditions of high abiotic stress. Our results suggest that warming and the associated soil drying could reduce primary production in many temperate grasslands, and that this will not necessarily be mitigated by efforts to maintain or increase species richness.

ASM Lecture Series: Global Warming and Climate Change

International Nuclear Information System (INIS)

Rowland, F. S.

2010-01-01

The melting of ice and permafrost in the north polar region and the shrinking of the tropical glaciers are signals that global warming is no longer solely a warning about the future, but changes which have already arrived. The initial effects of this warming are noticeably present, and the concerns are now of substantial climate change in the near future. Modeling of the consequences on the future atmosphere from increased release of greenhouse gases and some of the possible consequences of climate change, such as rising sea levels and melting of the north polar ice, are discussed. (author)

Response of climate to regional emissions of ozone precursors: sensitivities and warming potentials

International Nuclear Information System (INIS)

Berntsen, T.K.; Fuglestvedt, J.S.; Joshi, M.M.; Shine, K.P.; Hauglustaine, D.A.; Li, L.

2005-01-01

The response of climate to ozone perturbations caused by regional emissions of NO x or CO has been studied through a sequence of model simulations. Changes C and OH concentrations due to emission perturbations in Europe and southeast Asia have been calculated with two global 3-D chemical tracer models(CTMs; LMDzINCA and Oslo-CTM2). The radiative transfer codes of three general circulation models (GCMs; ECHAM4, UREAD and LMD) have been used to calculate the radiative forcing of the O 3 perturbations, and for a subset of the cases full GCM simulations have been performed with ECHAM4 and UREAD. The results have been aggregated to a global number in two ways: first, through integrating the global-mean radiative forcing of a sustained step change in emissions, and second through a modified concept (SGWP*) which includes possible differences in the climate sensitivity of O 3 , CH 4 and CO 2 changes. In terms of change in global tropospheric O 3 burden the two CTMs differ by less than 30%. Both CTMs show a higher north/south gradient in the sensitivity to changes in NO x emission than for CO. We are not able to conclude whether real O 3 perturbations in general have a different climate sensitivity from CO 2 . However, in both GCMs high-latitude emission perturbations lead to climate perturbations with higher (10-30%) climate sensitivities. The calculated SGWP*, for a 100 yr time horizon, are negative for three of the four CTM/GCM combinations for European emissions (-9.6 to +6.9), while for the Asian emissions the SGWP* (H=100) is always positive (+2.9 to +25) indicating a warming. For CO the SGWP* values (3.8 and 4.4 for European and Asian emissions respectively, with only the Oslo-CTM2/ECHAM4 model combination) are less regionally dependent. Our results support the view that for NO x , regionally different weighting factors for the emissions are necessary. For CO the results are more robust and one global number may be acceptable

Ecological responses to recent climate change

Energy Technology Data Exchange (ETDEWEB)

Walther, Gian-Reto [Hannover Univ., Inst. of Geobotany, Hannover (Germany); Post, Eric [Pennsylvania State Univ., Dept. of Biology, University Park, PA (United States); Convey, Peter [British Antarctic Survey, Natural Environment Research Council, Cambridge (United Kingdom); Menzel, Annette [Technical Univ. Munich, Dept. of Ecology, Freising (Germany); Parmesan, Camille [Texas Univ., Patterson Labs., Integrative Biology Dept., Austin, TX (United States); Beebee, Trevor J.C. [Sussex Univ., School of Biological Sciences, Brighton (United Kingdom); Fromentin, Jean-Marc [IFREMER, Centre Halieutique Mediterraneen et Tropical, Sete, 34 (France); Hoegh-Guldberg, Ove [Queensland Univ., Centre for Marine Studies, St Lucia, QLD (Australia); Bairlein, Franz [Institute for Avian Research ' Vogelwarte Helgoland' , Wilhelmshaven (Germany)

2002-03-28

There is now ample evidence of the ecological impacts of recent climate change, from polar terrestrial to tropical marine environments. The responses of both flora and fauna span an array of ecosystems and organisational hierarchies, from the species to the community levels. Despite continued uncertainty as to community and ecosystem trajectories under global change, our review exposes a coherent pattern of ecological change across systems. Although we are only at an early stage in the projected trends of global warming, ecological responses to recent climate change are already clearly visible. (Author)

Plant community structure regulates responses of prairie soil respiration to decadal experimental warming.

Science.gov (United States)

Xu, Xia; Shi, Zheng; Li, Dejun; Zhou, Xuhui; Sherry, Rebecca A; Luo, Yiqi

2015-10-01

Soil respiration is recognized to be influenced by temperature, moisture, and ecosystem production. However, little is known about how plant community structure regulates responses of soil respiration to climate change. Here, we used a 13-year field warming experiment to explore the mechanisms underlying plant community regulation on feedbacks of soil respiration to climate change in a tallgrass prairie in Oklahoma, USA. Infrared heaters were used to elevate temperature about 2 °C since November 1999. Annual clipping was used to mimic hay harvest. Our results showed that experimental warming significantly increased soil respiration approximately from 10% in the first 7 years (2000-2006) to 30% in the next 6 years (2007-2012). The two-stage warming stimulation of soil respiration was closely related to warming-induced increases in ecosystem production over the years. Moreover, we found that across the 13 years, warming-induced increases in soil respiration were positively affected by the proportion of aboveground net primary production (ANPP) contributed by C3 forbs. Functional composition of the plant community regulated warming-induced increases in soil respiration through the quantity and quality of organic matter inputs to soil and the amount of photosynthetic carbon (C) allocated belowground. Clipping, the interaction of clipping with warming, and warming-induced changes in soil temperature and moisture all had little effect on soil respiration over the years (all P > 0.05). Our results suggest that climate warming may drive an increase in soil respiration through altering composition of plant communities in grassland ecosystems. © 2015 John Wiley & Sons Ltd.

Insolation driven biomagnetic response to the Holocene Warm Period in semi-arid East Asia

Science.gov (United States)

Liu, Suzhen; Deng, Chenglong; Xiao, Jule; Li, Jinhua; Paterson, Greig A.; Chang, Liao; Yi, Liang; Qin, Huafeng; Pan, Yongxin; Zhu, Rixiang

2015-01-01

The Holocene Warm Period (HWP) provides valuable insights into the climate system and biotic responses to environmental variability and thus serves as an excellent analogue for future global climate changes. Here we document, for the first time, that warm and wet HWP conditions were highly favourable for magnetofossil proliferation in the semi-arid Asian interior. The pronounced increase of magnetofossil concentrations at ~9.8 ka and decrease at ~5.9 ka in Dali Lake coincided respectively with the onset and termination of the HWP, and are respectively linked to increased nutrient supply due to postglacial warming and poor nutrition due to drying at ~6 ka in the Asian interior. The two-stage transition at ~7.7 ka correlates well with increased organic carbon in middle HWP and suggests that improved climate conditions, leading to high quality nutrient influx, fostered magnetofossil proliferation. Our findings represent an excellent lake record in which magnetofossil abundance is, through nutrient availability, controlled by insolation driven climate changes.

Sustained climate warming drives declining marine biological productivity

Science.gov (United States)

Moore, J. Keith; Fu, Weiwei; Primeau, Francois; Britten, Gregory L.; Lindsay, Keith; Long, Matthew; Doney, Scott C.; Mahowald, Natalie; Hoffman, Forrest; Randerson, James T.

2018-03-01

Climate change projections to the year 2100 may miss physical-biogeochemical feedbacks that emerge later from the cumulative effects of climate warming. In a coupled climate simulation to the year 2300, the westerly winds strengthen and shift poleward, surface waters warm, and sea ice disappears, leading to intense nutrient trapping in the Southern Ocean. The trapping drives a global-scale nutrient redistribution, with net transfer to the deep ocean. Ensuing surface nutrient reductions north of 30°S drive steady declines in primary production and carbon export (decreases of 24 and 41%, respectively, by 2300). Potential fishery yields, constrained by lower–trophic-level productivity, decrease by more than 20% globally and by nearly 60% in the North Atlantic. Continued high levels of greenhouse gas emissions could suppress marine biological productivity for a millennium.

A meta-analysis of the response of soil moisture to experimental warming

International Nuclear Information System (INIS)

Xu, Wenfang; Yuan, Wenping; Dong, Wenjie; Xia, Jiangzhou; Liu, Dan; Chen, Yang

2013-01-01

Soil moisture is an important variable for regulating carbon, water and energy cycles of terrestrial ecosystems. However, numerous inconsistent conclusions have been reported regarding the responses of soil moisture to warming. In this study, we conducted a meta-analysis for examination of the response of soil moisture to experimental warming across global warming sites including several ecosystem types. The results showed that soil moisture decreased in response to warming treatments when compared with control treatments in most ecosystem types. The largest reduction of soil moisture was observed in forests, while intermediate reductions were observed in grassland and cropland, and they were both larger than the reductions observed in shrubland and tundra ecosystems. Increases (or no change) in soil moisture also occurred in some ecosystems. Taken together, these results showed a trend of soil drying in most ecosystems, which may have exerted profound impacts on a variety of terrestrial ecosystem processes as well as feedbacks to the climate system. (letter)

Isolating the atmospheric circulation response to Arctic sea-ice loss in the coupled climate system

Science.gov (United States)

Kushner, Paul; Blackport, Russell

2017-04-01

In the coupled climate system, projected global warming drives extensive sea-ice loss, but sea-ice loss drives warming that amplifies and can be confounded with the global warming process. This makes it challenging to cleanly attribute the atmospheric circulation response to sea-ice loss within coupled earth-system model (ESM) simulations of greenhouse warming. In this study, many centuries of output from coupled ocean/atmosphere/land/sea-ice ESM simulations driven separately by sea-ice albedo reduction and by projected greenhouse-dominated radiative forcing are combined to cleanly isolate the hemispheric scale response of the circulation to sea-ice loss. To isolate the sea-ice loss signal, a pattern scaling approach is proposed in which the local multidecadal mean atmospheric response is assumed to be separately proportional to the total sea-ice loss and to the total low latitude ocean surface warming. The proposed approach estimates the response to Arctic sea-ice loss with low latitude ocean temperatures fixed and vice versa. The sea-ice response includes a high northern latitude easterly zonal wind response, an equatorward shift of the eddy driven jet, a weakening of the stratospheric polar vortex, an anticyclonic sea level pressure anomaly over coastal Eurasia, a cyclonic sea level pressure anomaly over the North Pacific, and increased wintertime precipitation over the west coast of North America. Many of these responses are opposed by the response to low-latitude surface warming with sea ice fixed. However, both sea-ice loss and low latitude surface warming act in concert to reduce storm track strength throughout the mid and high latitudes. The responses are similar in two related versions of the National Center for Atmospheric Research earth system models, apart from the stratospheric polar vortex response. Evidence is presented that internal variability can easily contaminate the estimates if not enough independent climate states are used to construct them

Temperature-induced water stress in high-latitude forests in response to natural and anthropogenic warming.

Science.gov (United States)

Trahan, Matthew W; Schubert, Brian A

2016-02-01

The Arctic is particularly sensitive to climate change, but the independent effects of increasing atmospheric CO2 concentration (pCO2 ) and temperature on high-latitude forests are poorly understood. Here, we present a new, annually resolved record of stable carbon isotope (δ(13) C) data determined from Larix cajanderi tree cores collected from far northeastern Siberia in order to investigate the physiological response of these trees to regional warming. The tree-ring record, which extends from 1912 through 1961 (50 years), targets early twentieth-century warming (ETCW), a natural warming event in the 1920s to 1940s that was limited to Northern hemisphere high latitudes. Our data show that net carbon isotope fractionation (Δ(13) C), decreased by 1.7‰ across the ETCW, which is consistent with increased water stress in response to climate warming and dryer soils. To investigate whether this signal is present across the northern boreal forest, we compiled published carbon isotope data from 14 high-latitude sites within Europe, Asia, and North America. The resulting dataset covered the entire twentieth century and spanned both natural ETCW and anthropogenic Late Twentieth-Century Warming (~0.7 °C per decade). After correcting for a ~1‰ increase in Δ(13) C in response to twentieth century pCO2 rise, a significant negative relationship (r = -0.53, P forests across the twentieth century, of which approximately half is attributed to a decrease in stomatal conductance in order to conserve water in response to drying conditions, with the other half being attributed to increasing pCO2 . We conclude that annual tree-ring records from northern high-latitude forests record the effects of climate warming and pCO2 rise across the twentieth century. © 2015 John Wiley & Sons Ltd.

Effects of climate warming on net primary productivity in China during 1961-2010.

Science.gov (United States)

Gu, Fengxue; Zhang, Yuandong; Huang, Mei; Tao, Bo; Guo, Rui; Yan, Changrong

2017-09-01

The response of ecosystems to different magnitudes of climate warming and corresponding precipitation changes during the last few decades may provide an important reference for predicting the magnitude and trajectory of net primary productivity (NPP) in the future. In this study, a process-based ecosystem model, Carbon Exchange between Vegetation, Soil and Atmosphere (CEVSA), was used to investigate the response of NPP to warming at both national and subregional scales during 1961-2010. The results suggest that a 1.3°C increase in temperature stimulated the positive changing trend in NPP at national scale during the past 50 years. Regardless of the magnitude of temperature increase, warming enhanced the increase in NPP; however, the positive trend of NPP decreased when warming exceeded 2°C. The largest increase in NPP was found in regions where temperature increased by 1-2°C, and this rate of increase also contributed the most to the total increase in NPP in China's terrestrial ecosystems. Decreasing precipitation depressed the positive trend in NPP that was stimulated by warming. In northern China, warming depressed the increasing trend of NPP and warming that was accompanied by decreasing precipitation led to negative changing trends in NPP in large parts of northern China, especially when warming exceeded 2°C. However, warming stimulated the increase in NPP until warming was greater than 2°C, and decreased precipitation helped to increase the NPP in southern China.

Response of the North Pacific Oscillation to global warming in the models of the Intergovernmental Panel on Climate Change Fourth Assessment Report

Science.gov (United States)

Chen, Zheng; Gan, Bolan; Wu, Lixin

2017-09-01

Based on 22 of the climate models from phase 3 of the Coupled Model Intercomparison Project, we investigate the ability of the models to reproduce the spatiotemporal features of the wintertime North Pacific Oscillation (NPO), which is the second most important factor determining the wintertime sea level pressure field in simulations of the pre-industrial control climate, and evaluate the NPO response to the future most reasonable global warming scenario (the A1B scenario). We reveal that while most models simulate the geographic distribution and amplitude of the NPO pattern satisfactorily, only 13 models capture both features well. However, the temporal variability of the simulated NPO could not be significantly correlated with the observations. Further analysis indicates the weakened NPO intensity for a scenario of strong global warming is attributable to the reduced lower-tropospheric baroclinicity at mid-latitudes, which is anticipated to disrupt large-scale and low-frequency atmospheric variability, resulting in the diminished transfer of energy to the NPO, together with its northward shift.

Regional Climate Impacts of Stabilizing Global Warming at 1.5 K Using Solar Geoengineering

Science.gov (United States)

Jones, Anthony C.; Hawcroft, Matthew K.; Haywood, James M.; Jones, Andy; Guo, Xiaoran; Moore, John C.

2018-02-01

The 2015 Paris Agreement aims to limit global warming to well below 2 K above preindustrial levels, and to pursue efforts to limit global warming to 1.5 K, in order to avert dangerous climate change. However, current greenhouse gas emissions targets are more compatible with scenarios exhibiting end-of-century global warming of 2.6-3.1 K, in clear contradiction to the 1.5 K target. In this study, we use a global climate model to investigate the climatic impacts of using solar geoengineering by stratospheric aerosol injection to stabilize global-mean temperature at 1.5 K for the duration of the 21st century against three scenarios spanning the range of plausible greenhouse gas mitigation pathways (RCP2.6, RCP4.5, and RCP8.5). In addition to stabilizing global mean temperature and offsetting both Arctic sea-ice loss and thermosteric sea-level rise, we find that solar geoengineering could effectively counteract enhancements to the frequency of extreme storms in the North Atlantic and heatwaves in Europe, but would be less effective at counteracting hydrological changes in the Amazon basin and North Atlantic storm track displacement. In summary, solar geoengineering may reduce global mean impacts but is an imperfect solution at the regional level, where the effects of climate change are experienced. Our results should galvanize research into the regionality of climate responses to solar geoengineering.

Herbarium specimens show contrasting phenological responses to Himalayan climate.

Science.gov (United States)

Hart, Robbie; Salick, Jan; Ranjitkar, Sailesh; Xu, Jianchu

2014-07-22

Responses by flowering plants to climate change are complex and only beginning to be understood. Through analyses of 10,295 herbarium specimens of Himalayan Rhododendron collected by plant hunters and botanists since 1884, we were able to separate these responses into significant components. We found a lack of directional change in mean flowering time over the past 45 y of rapid warming. However, over the full 125 y of collections, mean flowering time shows a significant response to year-to-year changes in temperature, and this response varies with season of warming. Mean flowering advances with annual warming (2.27 d earlier per 1 °C warming), and also is delayed with fall warming (2.54 d later per 1 °C warming). Annual warming may advance flowering through positive effects on overwintering bud formation, whereas fall warming may delay flowering through an impact on chilling requirements. The lack of a directional response suggests that contrasting phenological responses to temperature changes may obscure temperature sensitivity in plants. By drawing on large collections from multiple herbaria, made over more than a century, we show how these data may inform studies even of remote localities, and we highlight the increasing value of these and other natural history collections in understanding long-term change.

Ocean cleaning stations under a changing climate: biological responses of tropical and temperate fish-cleaner shrimp to global warming.

Science.gov (United States)

Rosa, Rui; Lopes, Ana Rita; Pimentel, Marta; Faleiro, Filipa; Baptista, Miguel; Trübenbach, Katja; Narciso, Luis; Dionísio, Gisela; Pegado, Maria Rita; Repolho, Tiago; Calado, Ricardo; Diniz, Mário

2014-10-01

Cleaning symbioses play an important role in the health of certain coastal marine communities. These interspecific associations often occur at specific sites (cleaning stations) where a cleaner organism (commonly a fish or shrimp) removes ectoparasites/damaged tissue from a 'client' (a larger cooperating fish). At present, the potential impact of climate change on the fitness of cleaner organisms remains unknown. This study investigated the physiological and biochemical responses of tropical (Lysmata amboinensis) and temperate (L. seticaudata) cleaner shrimp to global warming. Specifically, thermal limits (CTMax), metabolic rates, thermal sensitivity, heat shock response (HSR), lipid peroxidation [malondialdehyde (MDA) concentration], lactate levels, antioxidant (GST, SOD and catalase) and digestive enzyme activities (trypsin and alkaline phosphatase) at current and warming (+3 °C) temperature conditions. In contrast to the temperate species, CTMax values decreased significantly from current (24-27 °C) to warming temperature conditions (30 °C) for the tropical shrimp, where metabolic thermal sensitivity was affected and the HSR was significantly reduced. MDA levels in tropical shrimp increased dramatically, indicating extreme cellular lipid peroxidation, which was not observed in the temperate shrimp. Lactate levels, GST and SOD activities were significantly enhanced within the muscle tissue of the tropical species. Digestive enzyme activities in the hepatopancreas of both species were significantly decreased by warmer temperatures. Our data suggest that the tropical cleaner shrimp will be more vulnerable to global warming than the temperate Lysmata seticaudata; the latter evolved in a relatively unstable environment with seasonal thermal variations that may have conferred greater adaptive plasticity. Thus, tropical cleaning symbioses may be challenged at a greater degree by warming-related anthropogenic forcing, with potential cascading effects on the health

Changes in Concurrent Risk of Warm and Dry Years under Impact of Climate Change

Science.gov (United States)

Sarhadi, A.; Wiper, M.; Touma, D. E.; Ausín, M. C.; Diffenbaugh, N. S.

2017-12-01

Anthropogenic global warming has changed the nature and the risk of extreme climate phenomena. The changing concurrence of multiple climatic extremes (warm and dry years) may result in intensification of undesirable consequences for water resources, human and ecosystem health, and environmental equity. The present study assesses how global warming influences the probability that warm and dry years co-occur in a global scale. In the first step of the study a designed multivariate Mann-Kendall trend analysis is used to detect the areas in which the concurrence of warm and dry years has increased in the historical climate records and also climate models in the global scale. The next step investigates the concurrent risk of the extremes under dynamic nonstationary conditions. A fully generalized multivariate risk framework is designed to evolve through time under dynamic nonstationary conditions. In this methodology, Bayesian, dynamic copulas are developed to model the time-varying dependence structure between the two different climate extremes (warm and dry years). The results reveal an increasing trend in the concurrence risk of warm and dry years, which are in agreement with the multivariate trend analysis from historical and climate models. In addition to providing a novel quantification of the changing probability of compound extreme events, the results of this study can help decision makers develop short- and long-term strategies to prepare for climate stresses now and in the future.

The responses of microbial temperature relationships to seasonal change and winter warming in a temperate grassland.

Science.gov (United States)

Birgander, Johanna; Olsson, Pål Axel; Rousk, Johannes

2018-01-18

Microorganisms dominate the decomposition of organic matter and their activities are strongly influenced by temperature. As the carbon (C) flux from soil to the atmosphere due to microbial activity is substantial, understanding temperature relationships of microbial processes is critical. It has been shown that microbial temperature relationships in soil correlate with the climate, and microorganisms in field experiments become more warm-tolerant in response to chronic warming. It is also known that microbial temperature relationships reflect the seasons in aquatic ecosystems, but to date this has not been investigated in soil. Although climate change predictions suggest that temperatures will be mostly affected during winter in temperate ecosystems, no assessments exist of the responses of microbial temperature relationships to winter warming. We investigated the responses of the temperature relationships of bacterial growth, fungal growth, and respiration in a temperate grassland to seasonal change, and to 2 years' winter warming. The warming treatments increased winter soil temperatures by 5-6°C, corresponding to 3°C warming of the mean annual temperature. Microbial temperature relationships and temperature sensitivities (Q 10 ) could be accurately established, but did not respond to winter warming or to seasonal temperature change, despite significant shifts in the microbial community structure. The lack of response to winter warming that we demonstrate, and the strong response to chronic warming treatments previously shown, together suggest that it is the peak annual soil temperature that influences the microbial temperature relationships, and that temperatures during colder seasons will have little impact. Thus, mean annual temperatures are poor predictors for microbial temperature relationships. Instead, the intensity of summer heat-spells in temperate systems is likely to shape the microbial temperature relationships that govern the soil-atmosphere C

Shifts in the microbial community structure explain the response of soil respiration to land-use change but not to climate warming

DEFF Research Database (Denmark)

Nazaries, Loïc; Tottey, William; Robinson, Lucinda

2015-01-01

Soil stores more carbon (C) than plants and atmosphere combined and it is vulnerable to increased microbial respiration under projected global changes including land-use change and future climate scenarios (mainly elevated temperature). Land-use change is known to have a direct impact on soil...... of this feedback response of Rs to global change. To identify the mechanisms of Rs response to land-use change and climate warming, we first investigated Rs from different land use types. Soil respiration was estimated seasonally from four different Scottish land uses: moorland, birch woodland, grassland and pine......, estimated by Multiplex Terminal-Restriction Fragment Length Polymorphism (MT-RFLP) and 454 pyrosequencing, was significantly different under each land use type. A strong correlation of Rs with soil properties (pH, inorganic N, C:N ratio and moisture) and with microbial community structure was identified...

Ethical choices and global climate warming

Energy Technology Data Exchange (ETDEWEB)

Dotto, L

1994-01-01

The ethical implications of global warming are discussed, and a summary is presented of a study on ethics and climate change. Deciding the 'best' approaches depends on point of view, whether this be of a Canadian, a Somali, great grandchildren, the Amazon rain forest or a kangaroo. The spectrum of possible actions runs from avoidance to adaptation. Avoidance focuses on strategies to reduce the greenhouse effect by curtailing greenhouse gas emissions or preventing these emissions from reaching the atmosphere. Adaptation strategies help to cope with the negative consequences of allowing emissions to continue. Philosophers and ethicists have expressed a wide range of opinions on the consequences, responsibilities, limitations, and legal mechanisms involved in determining global warming action. A profound shift in corporate thinking is called for, with less emphasis on short-term bottom line. The role of governments and other institutions is debated, and questions are raised about the economic strategies that will best protect the interests of future generations. Energy efficiency and conservation must be reflected in the economic equation. Public cynicism with regard to political leaders is such that they are unlikely to credited with any degree of ethical motivation, a view that may be unwarranted. Ethical principles must become more central in the formulation of policies.

High-resolution paleolimnology opens new management perspectives for lakes adaptation to climate warming

Directory of Open Access Journals (Sweden)

Marie-Elodie ePerga

2015-07-01

Full Text Available Varved lake sediments provide opportunities for high-resolution paleolimnological investigations that may extend monitoring surveys in order to target priority management actions under climate warming. This paper provides the synthesis of an international research program relying on >150 years-long, varved records for three managed perialpine lakes in Europe (Lakes Geneva, Annecy and Bourget. The dynamics of the dominant, local human pressures, as well as the ecological responses in the pelagic, benthic and littoral habitats were reconstructed using classical and newly developed paleo-proxies. Statistical modelling achieved the hierarchization of the drivers of their ecological trajectories. All three lakes underwent different levels of eutrophication in the first half of the XXth century, followed by re-oligotrophication. Climate warming came along with a 2°C increase in air temperature over the last century, to which lakes were unequally thermally vulnerable. Unsurprisingly, phosphorous concentration has been the dominant ecological driver over the last century. Yet, other human-influenced, local environmental drivers (fisheries management practices, river regulations have also significantly inflected ecological trajectories. Climate change has been impacting all habitats at rates that, in some cases, exceeded those of local factors. The amplitude and ecological responses to similar climate change varied between lakes, but, at least for pelagic habitats, rather depended on the intensity of local human pressures than on the thermal effect of climate change. Deep habitats yet showed higher sensitivity to climate change but substantial influence of river flows. As a consequence, adapted local management strategies, fully integrating nutrient inputs, fisheries management and hydrological regulations, may enable mitigating the deleterious consequences of ongoing climate change on these ecosystems.

El Niño/Southern Oscillation response to global warming

Science.gov (United States)

Latif, M.; Keenlyside, N. S.

2009-01-01

The El Niño/Southern Oscillation (ENSO) phenomenon, originating in the Tropical Pacific, is the strongest natural interannual climate signal and has widespread effects on the global climate system and the ecology of the Tropical Pacific. Any strong change in ENSO statistics will therefore have serious climatic and ecological consequences. Most global climate models do simulate ENSO, although large biases exist with respect to its characteristics. The ENSO response to global warming differs strongly from model to model and is thus highly uncertain. Some models simulate an increase in ENSO amplitude, others a decrease, and others virtually no change. Extremely strong changes constituting tipping point behavior are not simulated by any of the models. Nevertheless, some interesting changes in ENSO dynamics can be inferred from observations and model integrations. Although no tipping point behavior is envisaged in the physical climate system, smooth transitions in it may give rise to tipping point behavior in the biological, chemical, and even socioeconomic systems. For example, the simulated weakening of the Pacific zonal sea surface temperature gradient in the Hadley Centre model (with dynamic vegetation included) caused rapid Amazon forest die-back in the mid-twenty-first century, which in turn drove a nonlinear increase in atmospheric CO2, accelerating global warming. PMID:19060210

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.

Lagging adaptation to warming climate in Arabidopsis thaliana.

Science.gov (United States)

Wilczek, Amity M; Cooper, Martha D; Korves, Tonia M; Schmitt, Johanna

2014-06-03

If climate change outpaces the rate of adaptive evolution within a site, populations previously well adapted to local conditions may decline or disappear, and banked seeds from those populations will be unsuitable for restoring them. However, if such adaptational lag has occurred, immigrants from historically warmer climates will outperform natives and may provide genetic potential for evolutionary rescue. We tested for lagging adaptation to warming climate using banked seeds of the annual weed Arabidopsis thaliana in common garden experiments in four sites across the species' native European range: Valencia, Spain; Norwich, United Kingdom; Halle, Germany; and Oulu, Finland. Genotypes originating from geographic regions near the planting site had high relative fitness in each site, direct evidence for broad-scale geographic adaptation in this model species. However, genotypes originating in sites historically warmer than the planting site had higher average relative fitness than local genotypes in every site, especially at the northern range limit in Finland. This result suggests that local adaptive optima have shifted rapidly with recent warming across the species' native range. Climatic optima also differed among seasonal germination cohorts within the Norwich site, suggesting that populations occurring where summer germination is common may have greater evolutionary potential to persist under future warming. If adaptational lag has occurred over just a few decades in banked seeds of an annual species, it may be an important consideration for managing longer-lived species, as well as for attempts to conserve threatened populations through ex situ preservation.

Study of tropical clouds feedback to a climate warming as simulated by climate models

International Nuclear Information System (INIS)

Brient, Florent

2012-01-01

The last IPCC report affirms the predominant role of low cloud-radiative feedbacks in the inter-model spread of climate sensitivity. Understanding the mechanisms that control the behavior of low-level clouds is thus crucial. However, the complexity of coupled ocean-atmosphere models and the large number of processes potentially involved make the analysis of this response difficult. To simplify the analysis and to identify the most critical controls of cloud feedbacks, we analyze the cloud response to climate change simulated by the IPSL-CM5A model in a hierarchy of configurations. A comparison between three model configurations (coupled, atmospheric and aqua-planet) using the same physical parametrizations shows that the cloud response to global warming is dominated by a decrease of low clouds in regimes of moderate subsidence. Using a Single Column Model, forced by weak subsidence large-scale forcing, allows us to reproduce the vertical cloud profile predicted in the 3D model, as well as its response to climate change (if a stochastic forcing is added on vertical velocity). We analyze the sensitivity of this low-cloud response to external forcing and also to uncertain parameters of physical parameterizations involved on the atmospheric model. Through a moist static energy (MSE) budget, we highlight several mechanisms: (1) Robust: Over weak subsidence regimes, the Clausius-Clapeyron relationship predicts that a warmer atmosphere leads to a increase of the vertical MSE gradient, resulting on a strengthening of the import of low-MSE from the free atmosphere into the cloudy boundary layer. The MSE budget links changes of vertical advection and cloud radiative effects. (2) Physics Model Dependent: The coupling between shallow convection, turbulence and cloud schemes allows the intensification of low-MSE transport so that cloud radiative cooling becomes 'less necessary' to balance the energy budget (Robust positive low cloud-radiative feedback for the model). The

Permafrost response to increasing Arctic shrub abundance depends on the relative influence of shrubs on local soil cooling versus large-scale climate warming

International Nuclear Information System (INIS)

Lawrence, David M; Swenson, Sean C

2011-01-01

Deciduous shrub abundance is increasing across the Arctic in response to climatic warming. In a recent field manipulation experiment in which shrubs were removed from a plot and compared to a control plot with shrubs, Blok et al (2010 Glob. Change Biol. 16 1296–305) found that shrubs protect the ground through shading, resulting in a ∼ 9% shallower active layer thickness (ALT) under shrubs compared to grassy-tundra, which led them to argue that continued Arctic shrub expansion could mitigate future permafrost thaw. We utilize the Community Land Model (CLM4) coupled to the Community Atmosphere Model (CAM4) to evaluate this hypothesis. CLM4 simulates shallower ALT (∼− 11 cm) under shrubs, consistent with the field manipulation study. However, in an idealized pan-Arctic + 20% shrub area experiment, atmospheric heating, driven mainly by surface albedo changes related to protrusion of shrub stems above the spring snowpack, leads to soil warming and deeper ALT (∼+ 10 cm). Therefore, if climate feedbacks are considered, shrub expansion may actually increase rather than decrease permafrost vulnerability. When we account for blowing-snow redistribution from grassy-tundra to shrubs, shifts in snowpack distribution in low versus high shrub area simulations counter the climate warming impact, resulting in a grid cell mean ALT that is unchanged. These results reinforce the need to consider vegetation dynamics and blowing-snow processes in the permafrost thaw model projections.

Snowmelt response to simulated warming across a large elevation gradient, southern Sierra Nevada, California

Directory of Open Access Journals (Sweden)

K. N. Musselman

2017-12-01

Full Text Available In a warmer climate, the fraction of annual meltwater produced at high melt rates in mountainous areas is projected to decline due to a contraction of the snow-cover season, causing melt to occur earlier and under lower energy conditions. How snowmelt rates, including extreme events relevant to flood risk, may respond to a range of warming over a mountain front is poorly known. We present a model sensitivity study of snowmelt response to warming across a 3600 m elevation gradient in the southern Sierra Nevada, USA. A snow model was run for three distinct years and verified against extensive ground observations. To simulate the impact of climate warming on meltwater production, measured meteorological conditions were modified by +1 to +6 °C. The total annual snow water volume exhibited linear reductions (−10 % °C−1 consistent with previous studies. However, the sensitivity of snowmelt rates to successive degrees of warming varied nonlinearly with elevation. Middle elevations and years with more snowfall were prone to the largest reductions in snowmelt rates, with lesser changes simulated at higher elevations. Importantly, simulated warming causes extreme daily snowmelt (99th percentiles to increase in spatial extent and intensity, and shift from spring to winter. The results offer insight into the sensitivity of mountain snow water resources and how the rate and timing of water availability may change in a warmer climate. The identification of future climate conditions that may increase extreme melt events is needed to address the climate resilience of regional flood control systems.

Multi-scale responses to warming in an experimental insect metacommunity.

Science.gov (United States)

Grainger, Tess Nahanni; Gilbert, Benjamin

2017-12-01

In metacommunities, diversity is the product of species interactions at the local scale and dispersal between habitat patches at the regional scale. Although warming can alter both species interactions and dispersal, the combined effects of warming on these two processes remains uncertain. To determine the independent and interactive effects of warming-induced changes to local species interactions and dispersal, we constructed experimental metacommunities consisting of enclosed milkweed patches seeded with five herbivorous milkweed specialist insect species. We treated metacommunities with two levels of warming (unwarmed and warmed) and three levels of connectivity (isolated, low connectivity, high connectivity). Based on metabolic theory, we predicted that if plant resources were limited, warming would accelerate resource drawdown, causing local insect declines and increasing both insect dispersal and the importance of connectivity to neighboring patches for insect persistence. Conversely, given abundant resources, warming could have positive local effects on insects, and the risk of traversing a corridor to reach a neighboring patch could outweigh the benefits of additional resources. We found support for the latter scenario. Neither resource drawdown nor the weak insect-insect associations in our system were affected by warming, and most insect species did better locally in warmed conditions and had dispersal responses that were unchanged or indirectly affected by warming. Dispersal across the matrix posed a species-specific risk that led to declines in two species in connected metacommunities. Combined, this scaled up to cause an interactive effect of warming and connectivity on diversity, with unwarmed metacommunities with low connectivity incurring the most rapid declines in diversity. Overall, this study demonstrates the importance of integrating the complex outcomes of species interactions and spatial structure in understanding community response to climate

Warming patterns in regional climate change projections over the Iberian Peninsula

Energy Technology Data Exchange (ETDEWEB)

Gomez-Navarro, J.J.; Montavez, J.P.; Jimenez-Guerrero, P.; Jerez, S. [Murcia Univ. (Spain). Dept. de Fisica; Garcia-Valero, J.A. [Murcia Univ. (Spain). Dept. de Fisica; Delegacion Territorial en Murcia (ES). Agencia Estatal de Meteorologia (AEMET); Gonzalez-Rouco, J.F. [Univ. Complutense, Madrid (Spain). Dept. de Astrofisica y CC. de la Atmosfera

2010-06-15

A set of four regional climate change projections over the Iberian Peninsula has been performed. Simulations were driven by two General Circulation Models (consisting of two versions of the same atmospheric model coupled to two different ocean models) under two different SRES scenario. The XXI century has been simulated following a full-transient approach with a climate version of the mesoscale model MM5. An Empirical Orthogonal Function analysis (EOF) is applied to the monthly mean series of daily maximum and minimum 2-metre temperature to extract the warming signal. The first EOF is able to capture the spatial structure of the warming. The obtained warming patterns are fairly dependent on the month, but hardly change with the tested scenarios and GCM versions. Their shapes are related to geographical parameters, such as distance to the sea and orography. The main differences among simulations mostly concern the temporal evolution of the warming. The temperature trend is stronger for maximum temperatures and depends on the scenario and the driving GCM. This asymmetry, as well as the different warming rates in summer and winter, leads to a continentalization of the climate over the IP. (orig.)

Tributaries affect the thermal response of lakes to climate change

Science.gov (United States)

Råman Vinnå, Love; Wüest, Alfred; Zappa, Massimiliano; Fink, Gabriel; Bouffard, Damien

2018-01-01

Thermal responses of inland waters to climate change varies on global and regional scales. The extent of warming is determined by system-specific characteristics such as fluvial input. Here we examine the impact of ongoing climate change on two alpine tributaries, the Aare River and the Rhône River, and their respective downstream peri-alpine lakes: Lake Biel and Lake Geneva. We propagate regional atmospheric temperature effects into river discharge projections. These, together with anthropogenic heat sources, are in turn incorporated into simple and efficient deterministic models that predict future water temperatures, river-borne suspended sediment concentration (SSC), lake stratification and river intrusion depth/volume in the lakes. Climate-induced shifts in river discharge regimes, including seasonal flow variations, act as positive and negative feedbacks in influencing river water temperature and SSC. Differences in temperature and heating regimes between rivers and lakes in turn result in large seasonal shifts in warming of downstream lakes. The extent of this repressive effect on warming is controlled by the lakes hydraulic residence time. Previous studies suggest that climate change will diminish deep-water oxygen renewal in lakes. We find that climate-related seasonal variations in river temperatures and SSC shift deep penetrating river intrusions from summer towards winter. Thus potentially counteracting the otherwise negative effects associated with climate change on deep-water oxygen content. Our findings provide a template for evaluating the response of similar hydrologic systems to on-going climate change.

Tributaries affect the thermal response of lakes to climate change

Directory of Open Access Journals (Sweden)

L. Råman Vinnå

2018-01-01

Full Text Available Thermal responses of inland waters to climate change varies on global and regional scales. The extent of warming is determined by system-specific characteristics such as fluvial input. Here we examine the impact of ongoing climate change on two alpine tributaries, the Aare River and the Rhône River, and their respective downstream peri-alpine lakes: Lake Biel and Lake Geneva. We propagate regional atmospheric temperature effects into river discharge projections. These, together with anthropogenic heat sources, are in turn incorporated into simple and efficient deterministic models that predict future water temperatures, river-borne suspended sediment concentration (SSC, lake stratification and river intrusion depth/volume in the lakes. Climate-induced shifts in river discharge regimes, including seasonal flow variations, act as positive and negative feedbacks in influencing river water temperature and SSC. Differences in temperature and heating regimes between rivers and lakes in turn result in large seasonal shifts in warming of downstream lakes. The extent of this repressive effect on warming is controlled by the lakes hydraulic residence time. Previous studies suggest that climate change will diminish deep-water oxygen renewal in lakes. We find that climate-related seasonal variations in river temperatures and SSC shift deep penetrating river intrusions from summer towards winter. Thus potentially counteracting the otherwise negative effects associated with climate change on deep-water oxygen content. Our findings provide a template for evaluating the response of similar hydrologic systems to on-going climate change.

Climate warming and the decline of amphibians and reptiles in Europe

DEFF Research Database (Denmark)

Araújo, Miguel B.; Thuiller, W.; Pearson, R. G.

2006-01-01

deleterious than previously postulated; indeed, climate cooling would be more deleterious for the persistence of amphibian and reptile species than warming. The ability of species to cope with climate warming may, however, be offset by projected decreases in the availability of water. This should......-east are projected to gain suitable climate. This is because dry conditions in the south-west are projected to increase, approaching the levels found in North Africa, where few amphibian species are able to persist. Main conclusions The impact of increasing temperatures on amphibian and reptile species may be less...

The impact of possible climate catastrophes on global warming policy

International Nuclear Information System (INIS)

Baranzini, Andrea; Chesney, Marc; Morisset, Jacques

2003-01-01

Recent studies on global warming have introduced the inherent uncertainties associated with the costs and benefits of climate policies and have often shown that abatement policies are likely to be less aggressive or postponed in comparison to those resulting from traditional cost-benefit analyses (CBA). Yet, those studies have failed to include the possibility of sudden climate catastrophes. The aim of this paper is to account simultaneously for possible continuous and discrete damages resulting from global warming, and to analyse their implications on the optimal path of abatement policies. Our approach is related to the new literature on investment under uncertainty, and relies on some recent developments of the real option in which we incorporated negative jumps (climate catastrophes) in the stochastic process corresponding to the net benefits associated with the abatement policies. The impacts of continuous and discrete climatic risks can therefore be considered separately. Our numerical applications lead to two main conclusions: (i) gradual, continuous uncertainty in the global warming process is likely to delay the adoption of abatement policies as found in previous studies, with respect to the standard CBA; however (ii) the possibility of climate catastrophes accelerates the implementation of these policies as their net discounted benefits increase significantly

Climate warming and interannual variability of phytoplankton phenology in the Northern Red Sea

KAUST Repository

Gittings, John

2016-12-01

In agreement with global patterns of climate change and increasing temperatures in the tropical oceans, the Northern Red Sea (NRS) has been warming over the last few decades. Using 18 years of remotely-sensed chlorophyll-a data (Chl-a, an index of phytoplankton biomass), we investigate the potential impacts of climate warming on phytoplankton abundance and phenology in the Northern Red Sea by exploring the mechanistic links with the regional physical environment. The results of the analysis reveal that, in accordance with other tropical ecosystems, phytoplankton biomass in the NRS will decrease in response to warmer climate scenarios. This is attributed to lower heat fluxes (heat loss to the atmosphere) during the bloom period, and enhanced vertical stratification, which prevents vertical mixing of nutrients into the euphotic layer. In addition, we show that during warmer conditions (when heat fluxes are weakened), the winter bloom initiates significantly later (by up to 10 weeks) and its duration is considerably reduced. The biological implications of alterations to phytoplankton phenology may include increased larval mortality of pelagic species, reduced recruitment, fisheries impacts and changes to community structure.

Responses of mycorrhizal fungi and other rootassociated fungi to climate change

DEFF Research Database (Denmark)

Merrild, Marie Porret

Climate change is expected to affect many terrestrial ecosystem processes. Mycorrhizal fungi are important to soil carbon (C) and nutrient cycling thus changes in abundance of mycorrhizal fungi could alter ecosystem functioning. The aim of the present thesis was therefore to investigate responses...... of mycorrhizal fungi to climate change in a seasonal and long-term perspective. Effects of elevated CO2 (510 ppm), night-time warming and extended summer drought were investigated in the long-term field experiment CLIMAITE located in a Danish semi-natural heathland. Mycorrhizal colonization was investigated...... levels. Colonization by arbuscular mycorrhizal (AM) fungi increased under elevated CO2 and warming in spring while ericoid mycorrhiza (ErM) colonisation decreased in response to drought and warming. Increased AM colonization correlated with higher phosphorus and nitrogen root pools. Dark septate...

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.

Contrasted demographic responses facing future climate change in Southern Ocean seabirds.

Science.gov (United States)

Barbraud, Christophe; Rivalan, Philippe; Inchausti, Pablo; Nevoux, Marie; Rolland, Virginie; Weimerskirch, Henri

2011-01-01

1. Recent climate change has affected a wide range of species, but predicting population responses to projected climate change using population dynamics theory and models remains challenging, and very few attempts have been made. The Southern Ocean sea surface temperature and sea ice extent are projected to warm and shrink as concentrations of atmospheric greenhouse gases increase, and several top predator species are affected by fluctuations in these oceanographic variables. 2. We compared and projected the population responses of three seabird species living in sub-tropical, sub-Antarctic and Antarctic biomes to predicted climate change over the next 50 years. Using stochastic population models we combined long-term demographic datasets and projections of sea surface temperature and sea ice extent for three different IPCC emission scenarios (from most to least severe: A1B, A2, B1) from general circulation models of Earth's climate. 3. We found that climate mostly affected the probability to breed successfully, and in one case adult survival. Interestingly, frequent nonlinear relationships in demographic responses to climate were detected. Models forced by future predicted climatic change provided contrasted population responses depending on the species considered. The northernmost distributed species was predicted to be little affected by a future warming of the Southern Ocean, whereas steep declines were projected for the more southerly distributed species due to sea surface temperature warming and decrease in sea ice extent. For the most southerly distributed species, the A1B and B1 emission scenarios were respectively the most and less damaging. For the two other species, population responses were similar for all emission scenarios. 4. This is among the first attempts to study the demographic responses for several populations with contrasted environmental conditions, which illustrates that investigating the effects of climate change on core population dynamics

Response of precipitation extremes to idealized global warming in an aqua-planet climate model: Towards robust projection across different horizontal resolutions

Energy Technology Data Exchange (ETDEWEB)

Li, F.; Collins, W.D.; Wehner, M.F.; Williamson, D.L.; Olson, J.G.

2011-04-15

Current climate models produce quite heterogeneous projections for the responses of precipitation extremes to future climate change. To help understand the range of projections from multimodel ensembles, a series of idealized 'aquaplanet' Atmospheric General Circulation Model (AGCM) runs have been performed with the Community Atmosphere Model CAM3. These runs have been analysed to identify the effects of horizontal resolution on precipitation extreme projections under two simple global warming scenarios. We adopt the aquaplanet framework for our simulations to remove any sensitivity to the spatial resolution of external inputs and to focus on the roles of model physics and dynamics. Results show that a uniform increase of sea surface temperature (SST) and an increase of low-to-high latitude SST gradient both lead to increase of precipitation and precipitation extremes for most latitudes. The perturbed SSTs generally have stronger impacts on precipitation extremes than on mean precipitation. Horizontal model resolution strongly affects the global warming signals in the extreme precipitation in tropical and subtropical regions but not in high latitude regions. This study illustrates that the effects of horizontal resolution have to be taken into account to develop more robust projections of precipitation extremes.

Prediction of thermal sensation in non-air-conditioned buildings in warm climates

DEFF Research Database (Denmark)

Fanger, Povl Ole; Toftum, Jørn

2002-01-01

The PMV model agrees well with high-quality field studies in buildings with HVAC systems, situated in cold, temperate and warm climates, studied during both summer and winter. In non-air-conditioned buildings in warm climates, occupants may sense the warmth as being less severe than the PMV...... predicts. The main reason is low expectations, but a metabolic rate that is estimated too high can also contribute to explaining the difference. An extension of the PMV model that includes an expectancy factor is introduced for use in non-air-conditioned buildings in warm climates. The extended PMV model...... agrees well with quality field studies in non-air-conditioned buildings of three continents....

Climate warming: answering some basic questions

International Nuclear Information System (INIS)

Jancovici, J.M.

2009-01-01

Illustrated by many graphs, drawings, figures and tables, this long publication offers a detailed overview of the physical aspects of climatic change (definition of the greenhouse effect, explanation and assessment of warming, relationship and differences between greenhouse effect and ozone depletion, between climate change and greenhouse effect induced by human activity, and between meteorology and climate) and states some generalities on greenhouse effect gases. The author then discusses prospective issues on climatic change (notion of average temperature, role and liability of climate models, evolutions of temperatures and precipitations in different places, influence of greenhouse gas reduction), the various risks associated with climatic change (changes of sea currents, impact on ecosystems, diseases, ozone depletion, geographical differences, threat from methane hydrate). After a presentation of the carbon cycle, the next chapters are discussing the scientific discourses, the assessment of greenhouse effect in our everyday life, the impact of possible collective and individual actions, the relationship between greenhouse effect and economy, and strategic choices in France on airports and on nuclear energy

Acclimation of foliar respiration and photosynthesis in response to experimental warming in a temperate steppe in northern China.

Directory of Open Access Journals (Sweden)

Yonggang Chi

Full Text Available BACKGROUND: Thermal acclimation of foliar respiration and photosynthesis is critical for projection of changes in carbon exchange of terrestrial ecosystems under global warming. METHODOLOGY/PRINCIPAL FINDINGS: A field manipulative experiment was conducted to elevate foliar temperature (Tleaf by 2.07°C in a temperate steppe in northern China. Rd/Tleaf curves (responses of dark respiration to Tleaf, An/Tleaf curves (responses of light-saturated net CO2 assimilation rates to Tleaf, responses of biochemical limitations and diffusion limitations in gross CO2 assimilation rates (Ag to Tleaf, and foliar nitrogen (N concentration in Stipa krylovii Roshev. were measured in 2010 (a dry year and 2011 (a wet year. Significant thermal acclimation of Rd to 6-year experimental warming was found. However, An had a limited ability to acclimate to a warmer climate regime. Thermal acclimation of Rd was associated with not only the direct effects of warming, but also the changes in foliar N concentration induced by warming. CONCLUSIONS/SIGNIFICANCE: Warming decreased the temperature sensitivity (Q10 of the response of Rd/Ag ratio to Tleaf. Our findings may have important implications for improving ecosystem models in simulating carbon cycles and advancing understanding on the interactions between climate change and ecosystem functions.

Initial Response of the Nitrogen Cycle to Soil Warming and Elevated CO2 in Northern Minnesota Peatlands

Science.gov (United States)

Peatlands store 30% of global soil carbon. Many of these peatlands are located in boreal regions which are expected to have the highest temperature increases in response to climate change. As climate warms, peat decomposition may accelerate and release greenhouse gases. Spruce an...

Responses of lichen communities to 18 years of natural and experimental warming.

Science.gov (United States)

Alatalo, Juha M; Jägerbrand, Annika K; Chen, Shengbin; Molau, Ulf

2017-07-01

Climate change is expected to have major impacts on high alpine and arctic ecosystems in the future, but empirical data on the impact of long-term warming on lichen diversity and richness are sparse. This study report the effects of 18 years of ambient and experimental warming on lichens and vascular plant cover in two alpine plant communities, a dry heath with sparse canopy cover (54 %) and a mesic meadow with a more developed (67 %) canopy cover, in sub-arctic Sweden. The effects of long-term passive experimental warming using open top chambers (OTCs) on lichens and total vascular plant cover, and the impact of plant cover on lichen community parameters, were analysed. Between 1993 and 2013, mean annual temperature increased about 2 °C. Both site and experimental warming had a significant effect on cover, species richness, effective number of species evenness of lichens, and total plant canopy cover. Lichen cover increased in the heath under ambient conditions, and remained more stable under experimental warming. The negative effect on species richness and effective number of species was driven by a decrease in lichens under experimental warming in the meadow. Lichen cover, species richness, effective number of species evenness were negatively correlated with plant canopy cover. There was a significant negative impact on one species and a non-significant tendency of lower abundance of the most common species in response to experimental warming. The results from the long-term warming study imply that arctic and high alpine lichen communities are likely to be negatively affected by climate change and an increase in plant canopy cover. Both biotic and abiotic factors are thus important for future impacts of climate change on lichens. © The Author 2017. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com

Potential change in forest types and stand heights in central Siberia in a warming climate

International Nuclear Information System (INIS)

Tchebakova, N M; Parfenova, E I; Korets, M A; Conard, S G

2016-01-01

Previous regional studies in Siberia have demonstrated climate warming and associated changes in distribution of vegetation and forest types, starting at the end of the 20th century. In this study we used two regional bioclimatic envelope models to simulate potential changes in forest types distribution and developed new regression models to simulate changes in stand height in tablelands and southern mountains of central Siberia under warming 21st century climate. Stand height models were based on forest inventory data (2850 plots). The forest type and stand height maps were superimposed to identify how heights would change in different forest types in future climates. Climate projections from the general circulation model Hadley HadCM3 for emission scenarios B1 and A2 for 2080s were paired with the regional bioclimatic models. Under the harsh A2 scenario, simulated changes included: a 80%–90% decrease in forest-tundra and tundra, a 30% decrease in forest area, a ∼400% increase in forest-steppe, and a 2200% increase in steppe, forest-steppe and steppe would cover 55% of central Siberia. Under sufficiently moist conditions, the southern and middle taiga were simulated to benefit from 21st century climate warming. Habitats suitable for highly-productive forests (≥30–40 m stand height) were simulated to increase at the expense of less productive forests (10–20 m). In response to the more extreme A2 climate the area of these highly-productive forests would increase 10%–25%. Stand height increases of 10 m were simulated over 35%–50% of the current forest area in central Siberia. In the extremely warm A2 climate scenario, the tall trees (25–30 m) would occur over 8%–12% of area in all forest types except forest-tundra by the end of the century. In forest-steppe, trees of 30–40 m may cover some 15% of the area under sufficient moisture. (letter)

Australian climate extremes at 1.5 °C and 2 °C of global warming

Science.gov (United States)

King, Andrew D.; Karoly, David J.; Henley, Benjamin J.

2017-06-01

To avoid more severe impacts from climate change, there is international agreement to strive to limit warming to below 1.5 °C. However, there is a lack of literature assessing climate change at 1.5 °C and the potential benefits in terms of reduced frequency of extreme events. Here, we demonstrate that existing model simulations provide a basis for rapid and rigorous analysis of the effects of different levels of warming on large-scale climate extremes, using Australia as a case study. We show that limiting warming to 1.5 °C, relative to 2 °C, would perceptibly reduce the frequency of extreme heat events in Australia. The Australian continent experiences a variety of high-impact climate extremes that result in loss of life, and economic and environmental damage. Events similar to the record-hot summer of 2012-2013 and warm seas associated with bleaching of the Great Barrier Reef in 2016 would be substantially less likely, by about 25% in both cases, if warming is kept to lower levels. The benefits of limiting warming on hydrometeorological extremes are less clear. This study provides a framework for analysing climate extremes at 1.5 °C global warming.

Thermal Effectiveness of Wall Indoor Fountain in Warm Humid Climate

Science.gov (United States)

Seputra, J. A. P.

2018-03-01

Nowadays, many buildings wield indoor water features such as waterfalls, fountains, and water curtains to improve their aesthetical value. Despite the provision of air cooling due to water evaporation, this feature also has adverse effect if applied in warm humid climate since evaporation might increase air humidity beyond the comfort level. Yet, there are no specific researches intended to measure water feature’s effect upon its thermal condition. In response, this research examines the influence of evaporative cooling on indoor wall fountain toward occupant’s thermal comfort in warm humid climate. To achieve this goal, case study is established in Waroeng Steak Restaurant’s dining room in Surakarta-Indonesia. In addition, SNI 03-6572-2001 with comfort range of 20.5–27.1°C and 40-60% of relative humidity is utilized as thermal criterion. Furthermore, Computational Fluid Dynamics (CFD) is employed to process the data and derive conclusions. Research variables are; feature’s height, obstructions, and fan types. As results, Two Bumps Model (ToB) is appropriate when employs natural ventilation. However, if the room is mechanically ventilated, Three Bumps Model (TeB) becomes the best choice. Moreover, application of adaptive ventilation is required to maintain thermal balance.

Understanding the varied response of the extratropical storm tracks to climate change.

Science.gov (United States)

O'Gorman, Paul A

2010-11-09

Transient eddies in the extratropical storm tracks are a primary mechanism for the transport of momentum, energy, and water in the atmosphere, and as such are a major component of the climate system. Changes in the extratropical storm tracks under global warming would impact these transports, the ocean circulation and carbon cycle, and society through changing weather patterns. I show that the southern storm track intensifies in the multimodel mean of simulations of 21st century climate change, and that the seasonal cycle of storm-track intensity increases in amplitude in both hemispheres. I use observations of the present-day seasonal cycle to confirm the relationship between storm-track intensity and the mean available potential energy of the atmosphere, and show how this quantitative relationship can be used to account for much of the varied response in storm-track intensity to global warming, including substantially different responses in simulations with different climate models. The results suggest that storm-track intensity is not related in a simple way to global-mean surface temperature, so that, for example, a stronger southern storm track in response to present-day global warming does not imply it was also stronger in hothouse climates of the past.

A new mechanism for warm-season precipitation response to global warming based on convection-permitting simulations

Science.gov (United States)

Dai, Aiguo; Rasmussen, Roy M.; Liu, Changhai; Ikeda, Kyoko; Prein, Andreas F.

2017-08-01

Climate models project increasing precipitation intensity but decreasing frequency as greenhouse gases increase. However, the exact mechanism for the frequency decrease remains unclear. Here we investigate this by analyzing hourly data from regional climate change simulations with 4 km grid spacing covering most of North America using the Weather Research and Forecasting model. The model was forced with present and future boundary conditions, with the latter being derived by adding the CMIP5 19-model ensemble mean changes to the ERA-interim reanalysis. The model reproduces well the observed seasonal and spatial variations in precipitation frequency and histograms, and the dry interval between rain events over the contiguous US. Results show that overall precipitation frequency indeed decreases during the warm season mainly due to fewer light-moderate precipitation (0.1 2.0 mm/h) events, while heavy (2 10 mm/h) events increase. Dry spells become longer and more frequent, together with a reduction in time-mean relative humidity (RH) in the lower troposphere during the warm season. The increased dry hours and decreased RH lead to a reduction in overall precipitation frequency and also for light-moderate precipitation events, while water vapor-induced increases in precipitation intensity and the positive latent heating feedback in intense storms may be responsible for the large increase in intense precipitation. The size of intense storms increases while their number decreases in the future climate, which helps explain the increase in local frequency of heavy precipitation. The results generally support a new hypothesis for future warm-season precipitation: each rainstorm removes ≥7% more moisture from the air per 1 K local warming, and surface evaporation and moisture advection take slightly longer than currently to replenish the depleted moisture before the next storm forms, leading to longer dry spells and a reduction in precipitation frequency, as well as

Global warming from an energy perspective

International Nuclear Information System (INIS)

Edwards, A.G.

1991-01-01

Global climate change and energy are integrally related. The majority of greenhouse gas emissions are the result of energy production and use; at the same time, warming will affect energy patterns in California through physical increases in energy demand, physical changes in energy supply, and changes in both energy end-use patterns and supplies resulting from climate-change policies. There seems to be a growing political consensus that the world (as well as the state) needs to act soon to minimize further commitment to future warming. While California is not likely to experience the physical changes resulting from a warmer climate for years or perhaps decades, policy responses to the warming issue may cause more immediate impacts. This chapter will discuss how policy response to potential warming may be the most significant early impact of the issue on California's energy system. Makers of energy policy face the dilemma of deciding how to respond to the climate warming issue in the face of scientific uncertainties about its timing and seriousness. The chapter will conclude by presenting a conceptual framework for dealing with this dilemma, along with general recommendations for action

Comparing and contrasting Holocene and Eemian warm periods with greenhouse-gas-induced warming

International Nuclear Information System (INIS)

MacCracken, M.C.; Kutzbach, J.

1990-01-01

Periods of the past that are estimated to have been warmer than present are of great potential interest for comparison with simulations of future climates associated with greenhouse-gas-induced warming. Certain features of the climates of the mid-Holocene and Eemian periods, both interglacial maxima, are described. The simulated climatic responses to both types of forcing, in terms of land/ocean and latitudinal averages, are also compared. The zonal average and annual (or seasonal) average radiation fluxes associated with the different-from-present orbital conditions that existed for those interglacials are compared to the radiation flux associated with CO 2 -induced warming. There are some similarities but also significant differences in the two types of radiation flux perturbations, and there are both similarities and differences in the simulated climatic responses

Environmental Progression: The Psychological Justification for Reframing Climate Change and Global Warming

Science.gov (United States)

Veldey, S. H.

2016-12-01

On-going research in climate science communication through environmental media has uncovered critical barriers to reducing denial and increasing agency in addressing the threat of climate change. Similar to framing of our changing environment as "global warming", the term "climate change" also fails to properly frame the most critical challenge our species has faced. In a set of preliminary studies, significant changes in climate crisis denial, both positive and negative, have resulted from different media messaging. Continuation of this research utilizes social judgement theory (SJT) to classify a broader spectrum of effective avenues for environmental communication. The specificity of the terms global warming and climate change limit inclusion of issues critical to understanding their impacts. Now that the masses know what climate change is, it's time to teach them what it means.

Artificial climate warming positively affects arbuscular mycorrhizae but decreases soil aggregate water stability in an annual grassland

Energy Technology Data Exchange (ETDEWEB)

Rillig, M.C.; Wright, S.F.; Shaw, M.R.; Field, C.B.

2002-04-01

Despite the importance of arbuscular mycorrhizae to the functioning of terrestrial ecosystems (e.g. nutrient uptake, soil aggregation), and the increasing evidence of global warming, responses of arbuscular mycorrhizal fungi (AMF) to climate warming are poorly understood. In a field experiment using infrared heaters, we found effects of warming on AMF after one growing season in an annual grassland, in the absence of any effects on measured root parameters (weight, length, average diameter). AMF soil hyphal length was increased by over 40% in the warmed plots, accompanied by a strong trend for AMF root colonization increase. In the following year, root weight was again not significantly changed, and AMF root colonization increased significantly in the warmed plots. Concentration of the soil protein glomalin, a glycoprotein produced by AMF hyphae with importance in soil aggregation, was decreased in the warmed plots. Soil aggregate water stability, measured for five diameter size classes, was also decreased significantly. In the following year, soil aggregate weight in two size classes was decreased significantly, but the effect size was very small. These results indicate that ecosystem warming may have stimulated carbon allocation to AMF. Other factors either influenced glomalin decomposition or production, hence influencing the role of these symbionts in soil aggregation. The observed small changes in soil aggregation, if widespread among terrestrial ecosystems, could have important consequences for soil carbon storage and erosion in a warmed climate, especially if there are cumulative effects of warming. (au)

On the mechanisms of warming the mid-Pliocene and the inference of a hierarchy of climate sensitivities with relevance to the understanding of climate futures

Directory of Open Access Journals (Sweden)

D. Chandan

2018-06-01

Full Text Available We present results from our investigation into the physical mechanisms through which the mid-Pliocene, with a pCO2 of only  ∼  400 ppmv, could have supported the same magnitude of global warmth as has been projected for the climate at the end of the 21st century when pCO2 is expected to be 3 times higher. These mechanisms allow us to understand the warming in terms of changes to the radiative properties of the surface, the clouds, greenhouse gases, and changes to the meridional heat transport. We find that two-thirds of the warming pervasive during the mid-Pliocene, compared to the preindustrial, could be attributed to the reduction in the planetary emissivity owing to the higher concentrations of the greenhouse gases CO2 and water vapor, and the remaining one-third to the reduction in planetary albedo. We also find that changes to the orography and the pCO2 are the leading causes of the warming with each contributing in roughly equal parts to a total of 87 % of the warming and changes to the polar ice sheets responsible for the remaining warming. Furthermore, we provide a mid-Pliocene perspective on ongoing efforts to understand the climate system's sensitivity at various timescales and using multiple lines of evidence. The similarities in the boundary conditions between the mid-Pliocene and the present day, together with the globally elevated temperatures, make the mid-Pliocene an ideal paleo time period from which to derive inferences of climate sensitivity and assess the impacts of various timescale-dependent feedback processes. We assess a hierarchy of climate sensitivities of increasing complexity in order to explore the response of the climate over a very large range of timescales. The picture that emerges is as follows: on the short timescale, owing to the influence of fast feedback processes, the climate sensitivity is 3.25 °C per doubling of CO2; sensitivity increases to 4.16 °C per doubling of CO2 on an intermediate

Range position and climate sensitivity: The structure of among-population demographic responses to climatic variation

Science.gov (United States)

Amburgey, Staci M.; Miller, David A. W.; Grant, Evan H. Campbell; Rittenhouse, Tracy A. G.; Benard, Michael F.; Richardson, Jonathan L.; Urban, Mark C.; Hughson, Ward; Brand, Adrianne B,; Davis, Christopher J.; Hardin, Carmen R.; Paton, Peter W. C.; Raithel, Christopher J.; Relyea, Rick A.; Scott, A. Floyd; Skelly, David K.; Skidds, Dennis E.; Smith, Charles K.; Werner, Earl E.

2018-01-01

Species’ distributions will respond to climate change based on the relationship between local demographic processes and climate and how this relationship varies based on range position. A rarely tested demographic prediction is that populations at the extremes of a species’ climate envelope (e.g., populations in areas with the highest mean annual temperature) will be most sensitive to local shifts in climate (i.e., warming). We tested this prediction using a dynamic species distribution model linking demographic rates to variation in temperature and precipitation for wood frogs (Lithobates sylvaticus) in North America. Using long-term monitoring data from 746 populations in 27 study areas, we determined how climatic variation affected population growth rates and how these relationships varied with respect to long-term climate. Some models supported the predicted pattern, with negative effects of extreme summer temperatures in hotter areas and positive effects on recruitment for summer water availability in drier areas. We also found evidence of interacting temperature and precipitation influencing population size, such as extreme heat having less of a negative effect in wetter areas. Other results were contrary to predictions, such as positive effects of summer water availability in wetter parts of the range and positive responses to winter warming especially in milder areas. In general, we found wood frogs were more sensitive to changes in temperature or temperature interacting with precipitation than to changes in precipitation alone. Our results suggest that sensitivity to changes in climate cannot be predicted simply by knowing locations within the species’ climate envelope. Many climate processes did not affect population growth rates in the predicted direction based on range position. Processes such as species-interactions, local adaptation, and interactions with the physical landscape likely affect the responses we observed. Our work highlights the

Climate: a planet and men: what human influence on climate warming?

International Nuclear Information System (INIS)

Orsenna, E.; Petit, M.; Chabreuil, A. and others

2011-01-01

The authors, all members of the 'Argonauts club', have decided with other scientists, to write this book in order to allow the reader to make his own opinion about the influence of human activities on global warming. The book presents and supplies precise answers to the questions about the climate machine and its complex mechanisms according to the present day state of scientific knowledge. It takes stock of the actual climate situation and of the overall possible means at our disposal to limit the extent of the harmful anthropic impact. (J.S.)

Extension of the PMV model to non-air-conditioned building in warm climates

DEFF Research Database (Denmark)

Fanger, Povl Ole; Toftum, Jørn

2002-01-01

The PMV model agrees well with high-quality field studies in buildings with HVAC systems, situated in cold, temperate and warm climates, studied during both summer and winter. In non-air-conditioned buildings in warm climates, occupants may sense the warmth as being less severe than the PMV...... predicts. The main reason is low expectations, but a metabolic rate that is estimated too high can also contribute to explaining the difference. An extension of the PMV model that includes an expectancy factor is introduced for use in non-air-conditioned buildings in warm climates. The extended PMV model...... agrees well with quality field studies in non-air-conditioned buildings of three continents....

Life on a warmer earth: possible climatic consequences of man made global warming

Energy Technology Data Exchange (ETDEWEB)

Flohn, H

1981-01-01

The interaction between energy and climate is explored, including the impact on global climate of three main energy sources: solar, nuclear and fossil fuels. The global warming problem is introduced. Comprehensive analogies with warmer times are made. From the best models available, the future global average surface temperature is found and modified, describing the global warming effects caused by greenhouse effect caused by gases other than carbon dioxide, released into the atmosphere by man, i.e. nitrous oxide, methane, ammonia, and the chlorofluoromethanes. Paleoclimatic scenarios are reviewed, showing possible effects of global warming. An 800 to 1100 ppm CO/sub 2/ concentration causes irreversible Arctic melting, leading to displacement of present climatic zones by 400 to 800 km.

Temporal and Spatial Variation in Peatland Carbon Cycling and Implications for Interpreting Responses of an Ecosystem-Scale Warming Experiment

Science.gov (United States)

Natalie A. Griffiths; Paul J. Hanson; Daniel M. Ricciuto; Colleen M. Iversen; Anna M. Jensen; Avni Malhotra; Karis J. McFarlane; Richard J. Norby; Khachik Sargsyan; Stephen D. Sebestyen; Xiaoying Shi; Anthony P. Walker; Eric J. Ward; Jeffrey M. Warren; David J. Weston

2017-01-01

We are conducting a large-scale, long-term climate change response experiment in an ombrotrophic peat bog in Minnesota to evaluate the effects of warming and elevated CO2 on ecosystem processes using empirical and modeling approaches. To better frame future assessments of peatland responses to climate change, we characterized and compared spatial...

The climate response to five trillion tonnes of carbon

Science.gov (United States)

Tokarska, Katarzyna B.; Gillett, Nathan P.; Weaver, Andrew J.; Arora, Vivek K.; Eby, Michael

2016-09-01

Concrete actions to curtail greenhouse gas emissions have so far been limited on a global scale, and therefore the ultimate magnitude of climate change in the absence of further mitigation is an important consideration for climate policy. Estimates of fossil fuel reserves and resources are highly uncertain, and the amount used under a business-as-usual scenario would depend on prevailing economic and technological conditions. In the absence of global mitigation actions, five trillion tonnes of carbon (5 EgC), corresponding to the lower end of the range of estimates of the total fossil fuel resource, is often cited as an estimate of total cumulative emissions. An approximately linear relationship between global warming and cumulative CO2 emissions is known to hold up to 2 EgC emissions on decadal to centennial timescales; however, in some simple climate models the predicted warming at higher cumulative emissions is less than that predicted by such a linear relationship. Here, using simulations from four comprehensive Earth system models, we demonstrate that CO2-attributable warming continues to increase approximately linearly up to 5 EgC emissions. These models simulate, in response to 5 EgC of CO2 emissions, global mean warming of 6.4-9.5 °C, mean Arctic warming of 14.7-19.5 °C, and mean regional precipitation increases by more than a factor of four. These results indicate that the unregulated exploitation of the fossil fuel resource could ultimately result in considerably more profound climate changes than previously suggested.

Phytoplankton response to winter warming modified by large-bodied zooplankton: an experimental microcosm study

Directory of Open Access Journals (Sweden)

Hu He

2015-03-01

Full Text Available While several field investigations have demonstrated significant effects of cool season (winter or spring warming on phytoplankton development, the role played by large-bodied zooplankton grazers for the responses of phytoplankton to winter warming is ambiguous. We conducted an outdoor experiment to compare the effect of winter warming (heating by 3°C in combination with presence and absence of Daphnia grazing (D. similis on phytoplankton standing crops and community structure under eutrophic conditions. When Daphnia were absent, warming was associated with significant increases in phytoplankton biomass and cyanobacterial dominance. In contrast, when Daphnia were present, warming effects on phytoplankton dynamics were offset by warming-enhanced grazing, resulting in no significant change in biomass or taxonomic dominance. These results emphasize that large-bodied zooplankton like Daphnia spp. may play an important role in modulating the interactions between climate warming and phytoplankton dynamics in nutrient rich lake ecosystems.

Transient regional climate change: analysis of the summer climate response in a high-resolution, century-scale, ensemble experiment over the continental United States

Science.gov (United States)

Diffenbaugh, Noah S.; Ashfaq, Moetasim; Scherer, Martin

2013-01-01

Integrating the potential for climate change impacts into policy and planning decisions requires quantification of the emergence of sub-regional climate changes that could occur in response to transient changes in global radiative forcing. Here we report results from a high-resolution, century-scale, ensemble simulation of climate in the United States, forced by atmospheric constituent concentrations from the Special Report on Emissions Scenarios (SRES) A1B scenario. We find that 21st century summer warming permanently emerges beyond the baseline decadal-scale variability prior to 2020 over most areas of the continental U.S. Permanent emergence beyond the baseline annual-scale variability shows much greater spatial heterogeneity, with emergence occurring prior to 2030 over areas of the southwestern U.S., but not prior to the end of the 21st century over much of the southcentral and southeastern U.S. The pattern of emergence of robust summer warming contrasts with the pattern of summer warming magnitude, which is greatest over the central U.S. and smallest over the western U.S. In addition to stronger warming, the central U.S. also exhibits stronger coupling of changes in surface air temperature, precipitation, and moisture and energy fluxes, along with changes in atmospheric circulation towards increased anticylonic anomalies in the mid-troposphere and a poleward shift in the mid-latitude jet aloft. However, as a fraction of the baseline variability, the transient warming over the central U.S. is smaller than the warming over the southwestern or northeastern U.S., delaying the emergence of the warming signal over the central U.S. Our comparisons with observations and the Coupled Model Intercomparison Project Phase 3 (CMIP3) ensemble of global climate model experiments suggest that near-term global warming is likely to cause robust sub-regional-scale warming over areas that exhibit relatively little baseline variability. In contrast, where there is greater

Implications of climate change (global warming) for the healthcare system.

Science.gov (United States)

Raffa, R B; Eltoukhy, N S; Raffa, K F

2012-10-01

Temperature-sensitive pathogenic species and their vectors and hosts are emerging in previously colder regions as a consequence of several factors, including global warming. As a result, an increasing number of people will be exposed to pathogens against which they have not previously needed defences. We illustrate this with a specific example of recent emergence of Cryptococcus gattii infections in more temperate climates. The outbreaks in more temperate climates of the highly virulent--but usually tropically restricted--C. gattii is illustrative of an anticipated growing challenge for the healthcare system. There is a need for preparedness by healthcare professionals in anticipation and for management of such outbreaks, including other infections whose recent increased prevalence in temperate climates can be at least partly associated with global warming. (Re)emergence of temperature-sensitive pathogenic species in more temperate climates will present new challenges for healthcare systems. Preparation for outbreaks should precede their occurrence. © 2012 Blackwell Publishing Ltd.

National contributions to observed global warming

International Nuclear Information System (INIS)

Matthews, H Damon; Graham, Tanya L; Keverian, Serge; Lamontagne, Cassandra; Seto, Donny; Smith, Trevor J

2014-01-01

There is considerable interest in identifying national contributions to global warming as a way of allocating historical responsibility for observed climate change. This task is made difficult by uncertainty associated with national estimates of historical emissions, as well as by difficulty in estimating the climate response to emissions of gases with widely varying atmospheric lifetimes. Here, we present a new estimate of national contributions to observed climate warming, including CO 2 emissions from fossil fuels and land-use change, as well as methane, nitrous oxide and sulfate aerosol emissions While some countries’ warming contributions are reasonably well defined by fossil fuel CO 2 emissions, many countries have dominant contributions from land-use CO 2 and non-CO 2 greenhouse gas emissions, emphasizing the importance of both deforestation and agriculture as components of a country’s contribution to climate warming. Furthermore, because of their short atmospheric lifetime, recent sulfate aerosol emissions have a large impact on a country’s current climate contribution We show also that there are vast disparities in both total and per-capita climate contributions among countries, and that across most developed countries, per-capita contributions are not currently consistent with attempts to restrict global temperature change to less than 2 °C above pre-industrial temperatures. (paper)

The upper end of climate model temperature projections is inconsistent with past warming

International Nuclear Information System (INIS)

Stott, Peter; Good, Peter; Jones, Gareth; Gillett, Nathan; Hawkins, Ed

2013-01-01

Climate models predict a large range of possible future temperatures for a particular scenario of future emissions of greenhouse gases and other anthropogenic forcings of climate. Given that further warming in coming decades could threaten increasing risks of climatic disruption, it is important to determine whether model projections are consistent with temperature changes already observed. This can be achieved by quantifying the extent to which increases in well mixed greenhouse gases and changes in other anthropogenic and natural forcings have already altered temperature patterns around the globe. Here, for the first time, we combine multiple climate models into a single synthesized estimate of future warming rates consistent with past temperature changes. We show that the observed evolution of near-surface temperatures appears to indicate lower ranges (5–95%) for warming (0.35–0.82 K and 0.45–0.93 K by the 2020s (2020–9) relative to 1986–2005 under the RCP4.5 and 8.5 scenarios respectively) than the equivalent ranges projected by the CMIP5 climate models (0.48–1.00 K and 0.51–1.16 K respectively). Our results indicate that for each RCP the upper end of the range of CMIP5 climate model projections is inconsistent with past warming. (letter)

Grasshopper community response to climatic change: variation along an elevational gradient.

Science.gov (United States)

Nufio, César R; McGuire, Chris R; Bowers, M Deane; Guralnick, Robert P

2010-09-23

The impacts of climate change on phenological responses of species and communities are well-documented; however, many such studies are correlational and so less effective at assessing the causal links between changes in climate and changes in phenology. Using grasshopper communities found along an elevational gradient, we present an ideal system along the Front Range of Colorado USA that provides a mechanistic link between climate and phenology. This study utilizes past (1959-1960) and present (2006-2008) surveys of grasshopper communities and daily temperature records to quantify the relationship between amount and timing of warming across years and elevations, and grasshopper timing to adulthood. Grasshopper communities were surveyed at four sites, Chautauqua Mesa (1752 m), A1 (2195 m), B1 (2591 m), and C1 (3048 m), located in prairie, lower montane, upper montane, and subalpine life zones, respectively. Changes to earlier first appearance of adults depended on the degree to which a site warmed. The lowest site showed little warming and little phenological advancement. The next highest site (A1) warmed a small, but significant, amount and grasshopper species there showed inconsistent phenological advancements. The two highest sites warmed the most, and at these sites grasshoppers showed significant phenological advancements. At these sites, late-developing species showed the greatest advancements, a pattern that correlated with an increase in rate of late-season warming. The number of growing degree days (GDDs) associated with the time to adulthood for a species was unchanged across the past and present surveys, suggesting that phenological advancement depended on when a set number of GDDs is reached during a season. Our analyses provide clear evidence that variation in amount and timing of warming over the growing season explains the vast majority of phenological variation in this system. Our results move past simple correlation and provide a stronger process

Grasshopper community response to climatic change: variation along an elevational gradient.

Directory of Open Access Journals (Sweden)

César R Nufio

2010-09-01

Full Text Available The impacts of climate change on phenological responses of species and communities are well-documented; however, many such studies are correlational and so less effective at assessing the causal links between changes in climate and changes in phenology. Using grasshopper communities found along an elevational gradient, we present an ideal system along the Front Range of Colorado USA that provides a mechanistic link between climate and phenology.This study utilizes past (1959-1960 and present (2006-2008 surveys of grasshopper communities and daily temperature records to quantify the relationship between amount and timing of warming across years and elevations, and grasshopper timing to adulthood. Grasshopper communities were surveyed at four sites, Chautauqua Mesa (1752 m, A1 (2195 m, B1 (2591 m, and C1 (3048 m, located in prairie, lower montane, upper montane, and subalpine life zones, respectively. Changes to earlier first appearance of adults depended on the degree to which a site warmed. The lowest site showed little warming and little phenological advancement. The next highest site (A1 warmed a small, but significant, amount and grasshopper species there showed inconsistent phenological advancements. The two highest sites warmed the most, and at these sites grasshoppers showed significant phenological advancements. At these sites, late-developing species showed the greatest advancements, a pattern that correlated with an increase in rate of late-season warming. The number of growing degree days (GDDs associated with the time to adulthood for a species was unchanged across the past and present surveys, suggesting that phenological advancement depended on when a set number of GDDs is reached during a season.Our analyses provide clear evidence that variation in amount and timing of warming over the growing season explains the vast majority of phenological variation in this system. Our results move past simple correlation and provide a stronger

Arctic ecosystem responses to a warming climate

DEFF Research Database (Denmark)

Mortensen, Lars O.

sheet, loss of multiannual sea-ice and significant advances in snowmelt days. The biotic components of the arctic ecosystem have also been affected by the rapid changes in climate, for instance resulting in the collapse of the collared lemming cycle, advances in spring flowering and changes in the intra...... biotic interactions. Hence, through the use of up-to-date multivariate statistical tools, this Ph.D. study has been concerned with analyzing how the observed rapid climate changes are affecting the arctic ecosystems. The primary tool has been the implementation of structural equation modeling (SEM) which....... Additionally, the study demonstrated that climate effects had distinct direct and indirect effects on different trophic levels, indicating cascading effects of climate through the trophic system. Results suggest that the Arctic is being significantly affected by the observed climate changes and depending...

Dominance of climate warming effects on recent drying trends over wet monsoon regions

Science.gov (United States)

Park, Chang-Eui; Jeong, Su-Jong; Ho, Chang-Hoi; Park, Hoonyoung; Piao, Shilong; Kim, Jinwon; Feng, Song

2017-09-01

Understanding changes in background dryness over land is key information for adapting to climate change because of its critical socioeconomic consequences. However, causes of continental dryness changes remain uncertain because various climate parameters control dryness. Here, we verify dominant climate variables determining dryness trends over continental eastern Asia, which is characterized by diverse hydroclimate regimes ranging from arid to humid, by quantifying the relative effects of changes in precipitation, solar radiation, wind speed, surface air temperature, and relative humidity on trends in the aridity index based on observed data from 189 weather stations for the period of 1961-2010. Before the early 1980s (1961-1983), change in precipitation is a primary condition for determining aridity trends. In the later period (1984-2010), the dominant climate parameter for aridity trends varies according to the hydroclimate regime. Drying trends in arid regions are mostly explained by reduced precipitation. In contrast, the increase in potential evapotranspiration due to increased atmospheric water-holding capacity, a secondary impact of warming, works to increase aridity over the humid monsoon region despite an enhanced water supply and relatively less warming. Our results show significant drying effects of warming over the humid monsoon region in recent decades; this also supports the drying trends over warm and water-sufficient regions in future climate.

Precipitation response to the current ENSO variability in a warming world

Science.gov (United States)

Bonfils, C.; Santer, B. D.; Phillips, T. J.; Marvel, K.; Leung, L.

2013-12-01

The major triggers of past and recent droughts include large modes of variability, such as ENSO, as well as specific and persistent patterns of sea surface temperature anomalies (SSTAs; Hoerling and Kumar, 2003, Shin et al. 2010, Schubert et al. 2009). However, alternative drought initiators are also anticipated in response to increasing greenhouse gases, potentially changing the relative contribution of ocean variability as drought initiator. They include the intensification of the current zonal wet-dry patterns (the thermodynamic mechanism, Held and Soden, 2006), a latitudinal redistribution of global precipitation (the dynamical mechanism, Seager et al. 2007, Seidel et al. 2008, Scheff and Frierson 2008) and a reduction of local soil moisture and precipitation recycling (the land-atmosphere argument). Our ultimate goal is to investigate whether the relative contribution of those mechanisms change over time in response to global warming. In this study, we first perform an EOF analysis of the 1900-1999 time series of observed global SST field and identify a simple ENSO-like (ENSOL) mode of SST variability. We show that this mode is well spatially and temporally correlated with observed worldwide regional precipitation and drought variability. We then develop concise metrics to examine the fidelity with which the CMIP5 coupled global climate models (CGCMs) capture this particular ENSO-like mode in the current climate, and their ability to replicate the observed teleconnections with precipitation. Based on the CMIP5 model projections of future climate change, we finally analyze the potential temporal variations in ENSOL to be anticipated under further global warming, as well as their associated teleconnections with precipitation (pattern, amplitude, and total response). Overall, our approach allows us to determine what will be the effect of the current ENSO-like variability (i.e., as measured with instrumental observations) on precipitation in a warming world. This

N cycling in SPRUCE (Spruce Peatlands Response Under Climatic and Environmental Changes)

Science.gov (United States)

Peatlands located in boreal regions make up a third of global wetland area and are expected to have the highest temperature increases in response to climate change. As climate warms, we expect peat decomposition may accelerate, altering the cycling of nitrogen. Alterations in th...

Climate change and global warming potentials

International Nuclear Information System (INIS)

Vate, J.F. van de

1996-01-01

Climate change and the global budgets of the two main energy consumption related greenhouse gases, CO 2 and CH 4 , are discussed. The global warming potential (GWP) of the non-CO 2 greenhouse gases is defined and the large range of GWPs of CH 4 in the literature is discussed. GWPs are expected to play an important role in energy policies and negotiations concerning lowering greenhouse gas emissions. (author). 20 refs, 4 figs, 4 tabs

The regions and global warming: Impacts and response strategies

International Nuclear Information System (INIS)

1991-01-01

To date, much of the attention given to global warming in scientific research as well as in policy development has focused on the global picture. International negotiations and agreements to stabilize, and eventually reduce, greenhouse gas emissions are very important. By themselves, however, they are not sufficient to address global warming. Regional strategies are also needed. They can help reduce greenhouse gas emissions, and they will be the most effective way to mitigate the consequences of global warming. Adaptive strategies must respond to local and regional conditions. In many countries, subnational jurisdictions such as states and provinces or community organizations can already take effective actions without direction from their national government or waiting for international agreements. An important factor in defining regional approaches is the disparate consequences of climate change for developed and developing areas. Different strategies will also be needed for industrial and agricultural regions. Wealthy industrial regions may be better able to develop capital-intensive, adaptive infrastructure than regions with fewer discretionary resources where people are more vulnerable to the vagaries of weather patterns. On the other hand, regions that rely on indigenous knowledge and local resources may be better equipped to make incremental adaptations and more willing to modify life-styles. Ultimately, all climate change effects are experienced in specific places and effective response depends upon local action. We recognize that individual localities cannot solve a problem of global proportions by acting alone. However, a regional strategy can supplement international and national action and be the focal point for addressing risks in the unique social and economic context of a particular area. These meetings discussions dealt with the impacts and implications of climate change on such things as agriculture, forestry, and policy

Common metrics. Comparing the warming effect of climate forcers in climate policy; Common metrics. Laempenemiseen vaikuttavien paeaestoejen yhteismitallistaminen ilmastopolitiikassa

Energy Technology Data Exchange (ETDEWEB)

Lindroos, T. J.; Ekholm, T.; Savolainen, I.

2012-11-15

Climate policy needs a relatively simple method to compare the warming effect of different greenhouse gases (GHGs). Otherwise it would be necessary to negotiate a different reduction target for each gas. At the moment, Global Warming Potential (GWP) concept is used to compare different GHGs. Numerical values of GWP factors have been updated alongside with scientific understanding and majority seems content to the GWP. From 2005 onwards there have been many proposals of optional metrics. The most well known is Global Temperature change Potential (GTP) concept which measures the change of temperature as does global climate policies. The decision between metrics is a multicriteria decision which should include at least the coherence with climate policy and cost efficiency. The GWP concept may be a little more difficult to understand than the GTP but it is more cost efficient. Alongside with new metrics, scientists and politicians have started to discuss of new emission which have an effect on warming. These Short Lived Climate Forcers (SLCFs) have either warming or cooling effect. Their effect can be presented with GWP and GTP but the uncertainties in the emission factors are large. In total, SLCFs reduce overall emissions of EU approximately 1% in year 2000. NO{sub x}, SO{sub x} (cooling) and black carbon (warming) emissions were the biggest factors. EU is planning to reduce the SLCF emissions to achieve health and environmental benefits, but at the same time this reduces the effect of EU's climate policies by approximately 10%. Uncertainties in the estimates are large. (orig.)

New use of global warming potentials to compare cumulative and short-lived climate pollutants

Science.gov (United States)

Allen, Myles R.; Fuglestvedt, Jan S.; Shine, Keith P.; Reisinger, Andy; Pierrehumbert, Raymond T.; Forster, Piers M.

2016-08-01

Parties to the United Nations Framework Convention on Climate Change (UNFCCC) have requested guidance on common greenhouse gas metrics in accounting for Nationally determined contributions (NDCs) to emission reductions. Metric choice can affect the relative emphasis placed on reductions of `cumulative climate pollutants' such as carbon dioxide versus `short-lived climate pollutants' (SLCPs), including methane and black carbon. Here we show that the widely used 100-year global warming potential (GWP100) effectively measures the relative impact of both cumulative pollutants and SLCPs on realized warming 20-40 years after the time of emission. If the overall goal of climate policy is to limit peak warming, GWP100 therefore overstates the importance of current SLCP emissions unless stringent and immediate reductions of all climate pollutants result in temperatures nearing their peak soon after mid-century, which may be necessary to limit warming to ``well below 2 °C'' (ref. ). The GWP100 can be used to approximately equate a one-off pulse emission of a cumulative pollutant and an indefinitely sustained change in the rate of emission of an SLCP. The climate implications of traditional CO2-equivalent targets are ambiguous unless contributions from cumulative pollutants and SLCPs are specified separately.

Climate change affects low trophic level marine consumers: warming decreases copepod size and abundance.

Science.gov (United States)

Garzke, Jessica; Ismar, Stefanie M H; Sommer, Ulrich

2015-03-01

Concern about climate change has re-ignited interest in universal ecological responses to temperature variations: (1) biogeographical shifts, (2) phenology changes, and (3) size shifts. In this study we used copepods as model organisms to study size responses to temperature because of their central role in the pelagic food web and because of the ontogenetic length constancy between molts, which facilitates the definition of size of distinct developmental stages. In order to test the expected temperature-induced shifts towards smaller body size and lower abundances under warming conditions, a mesocosm experiment using plankton from the Baltic Sea at three temperature levels (ambient, ambient +4 °C, ambient -4 °C) was performed in summer 2010. Overall copepod and copepodit abundances, copepod size at all life stages, and adult copepod size in particular, showed significant temperature effects. As expected, zooplankton peak abundance was lower in warm than in ambient treatments. Copepod size-at-immature stage significantly increased in cold treatments, while adult size significantly decreased in warm treatments.

Investigations of the Climate System Response to Climate Engineering in a Hierarchy of Models

Science.gov (United States)

McCusker, Kelly E.

Global warming due to anthropogenic emissions of greenhouse gases is causing negative impacts on diverse ecological and human systems around the globe, and these impacts are projected to worsen as climate continues to warm. In the absence of meaningful greenhouse gas emissions reductions, new strategies have been proposed to engineer the climate, with the aim of preventing further warming and avoiding associated climate impacts. We investigate one such strategy here, falling under the umbrella of `solar radiation management', in which sulfate aerosols are injected into the stratosphere. We use a global climate model with a coupled mixed-layer depth ocean and with a fully-coupled ocean general circulation model to simulate the stabilization of climate by balancing increasing carbon dioxide with increasing stratospheric sulfate concentrations. We evaluate whether or not severe climate impacts, such as melting Arctic sea ice, tropical crop failure, or destabilization of the West Antarctic ice sheet, could be avoided. We find that while tropical climate emergencies might be avoided by use of stratospheric aerosol injections, avoiding polar emergencies cannot be guaranteed due to large residual climate changes in those regions, which are in part due to residual atmospheric circulation anomalies. We also find that the inclusion of a fully-coupled ocean is important for determining the regional climate response because of its dynamical feedbacks. The efficacy of stratospheric sulfate aerosol injections, and solar radiation management more generally, depends on its ability to be maintained indefinitely, without interruption from a variety of possible sources, such as technological failure, a breakdown in global cooperation, lack of funding, or negative unintended consequences. We next consider the scenario in which stratospheric sulfate injections are abruptly terminated after a multi- decadal period of implementation while greenhouse gas emissions have continued unabated

A real-time Global Warming Index.

Science.gov (United States)

Haustein, K; Allen, M R; Forster, P M; Otto, F E L; Mitchell, D M; Matthews, H D; Frame, D J

2017-11-13

We propose a simple real-time index of global human-induced warming and assess its robustness to uncertainties in climate forcing and short-term climate fluctuations. This index provides improved scientific context for temperature stabilisation targets and has the potential to decrease the volatility of climate policy. We quantify uncertainties arising from temperature observations, climate radiative forcings, internal variability and the model response. Our index and the associated rate of human-induced warming is compatible with a range of other more sophisticated methods to estimate the human contribution to observed global temperature change.

Fine Root Growth and Vertical Distribution in Response to Elevated CO2, Warming and Drought in a Mixed Heathland–Grassland

DEFF Research Database (Denmark)

Arndal, Marie Frost; Tolver, Anders; Larsen, Klaus Steenberg

2018-01-01

in single-factor experiments. In a Danish heathland ecosystem, we investigated both individual and combined effects of elevated CO2, warming and drought on fine root length, net production and standing biomass by the use of minirhizotrons, ingrowth cores and soil coring. Warming increased the net root...... production from ingrowth cores, but decreased fine root number and length in minirhizotrons, whereas there were no significant main effects of drought. Across all treatments and soil depths, CO2 stimulated both the total fine root length (+44%) and the number of roots observed (+39%), with highest relative......Belowground plant responses have received much less attention in climate change experiments than aboveground plant responses, thus hampering a holistic understanding of climate change effects on plants and ecosystems. In addition, responses of plant roots to climate change have mostly been studied...

Dominance of climate warming effects on recent drying trends over wet monsoon regions

Directory of Open Access Journals (Sweden)

C.-E. Park

2017-09-01

Full Text Available Understanding changes in background dryness over land is key information for adapting to climate change because of its critical socioeconomic consequences. However, causes of continental dryness changes remain uncertain because various climate parameters control dryness. Here, we verify dominant climate variables determining dryness trends over continental eastern Asia, which is characterized by diverse hydroclimate regimes ranging from arid to humid, by quantifying the relative effects of changes in precipitation, solar radiation, wind speed, surface air temperature, and relative humidity on trends in the aridity index based on observed data from 189 weather stations for the period of 1961–2010. Before the early 1980s (1961–1983, change in precipitation is a primary condition for determining aridity trends. In the later period (1984–2010, the dominant climate parameter for aridity trends varies according to the hydroclimate regime. Drying trends in arid regions are mostly explained by reduced precipitation. In contrast, the increase in potential evapotranspiration due to increased atmospheric water-holding capacity, a secondary impact of warming, works to increase aridity over the humid monsoon region despite an enhanced water supply and relatively less warming. Our results show significant drying effects of warming over the humid monsoon region in recent decades; this also supports the drying trends over warm and water-sufficient regions in future climate.

Glacial changes in warm pool climate dominated by shelf exposure and ice sheet albedo

Science.gov (United States)

Di Nezio, P. N.; Tierney, J. E.; Otto-Bliesner, B. L.; Timmermann, A.; Bhattacharya, T.; Brady, E. C.; Rosenbloom, N. A.

2017-12-01

The mechanisms driving glacial-interglacial changes in the climate of the Indo-Pacific warm pool (IPWP) are unclear. We addressed this issue combining model simulations and paleoclimate reconstructions of the Last Glacial Maximum (LGM). Two drivers - the exposure of tropical shelves due to lower sea level and a monsoonal response to ice sheet albedo - explain the proxy-inferred patterns of hydroclimate change. Shelf exposure influences IPWP climate by weakening the ascending branch of the Walker circulation. This response is amplified by coupled interactions akin to the Bjerknes feedback involving a stronger sea-surface temperature (SST) gradient along the equatorial Indian Ocean (IO). Ice sheet albedo enhances the import of cold, dry air into the tropics, weakening the Afro-Asian monsoon system. This "ventilation" mechanism alters temperature contrasts between the Arabian Sea and surrounding land leading to further monsoon weakening. Additional simulations show that the altered SST patterns associated with these responses are essential for explaining the proxy-inferred changes. Together our results show that ice sheets are a first order driver of tropical climate on glacial-interglacial timescales. While glacial climates are not a straightforward analogue for the future, our finding of an active Bjerknes feedback deserves further attention in the context of future climate projections.

Atlantic Warm Pool Trigger for the Younger Dryas Climate Event

Science.gov (United States)

Abdul, N. A.; Mortlock, R. A.; Wright, J. D.; Fairbanks, R. G.; Teneva, L. T.

2011-12-01

There is growing evidence that variability in the size and heat content of the tropical Atlantic Warm Pool impacts circum-North Atlantic climate via the Atlantic Multi-decadal Oscillation mode (Wang et al., 2008). The Atlantic Warm Pool spans the Gulf of Mexico, Caribbean Sea and the western tropical North Atlantic. Barbados is located near the center of the tropical Atlantic Warm Pool and coupled ocean models suggest that Barbados remains near the center of the tropical Atlantic Warm Pool under varying wind stress simulations. Measurements of the oxygen isotope paleothermometer in Acropora palmata coral species recovered from cores offshore Barbados, show a 3oC monotonic decrease in sea surface temperature from 13106 ± 83 to 12744 ± 61 years before present (errors given as 2 sigma). This interval corresponds to a sea level rise from 71.4 meters to 67.1 meters below present levels at Barbados. The 3oC temperature decrease is captured in eight A. palmata specimens that are in stratigraphic sequence, 230Th/234U dated, and analyzed for oxygen isotopes. All measurements are replicated. We are confident that this is the warm pool equivalent of the Younger Dryas climate event. The initiation of this temperature drop in the Atlantic Warm Pool predates the Younger Dryas start in Greenland ice cores, reported to start at 12896 ± 138 years (relative to AD 2000) (Rasmussen et al., 2006), while few other Younger Dryas climate records are dated with similar accuracy to make the comparison. Rasmussen, S.O., Andersen, K.K., Svensson, A.M., Steffensen, J.P., Vinther, B.M., Clausen, H.B., Siggaard-Andersen, M.L., Johnsen, S.J., Larsen, L.B., Dahl-Jensen, D., Bigler, M., Röthlisberger, R., Fischer, H., Goto-Azuma, K., Hansson, M.E., and Ruth, U., 2006, A new Greenland ice core chronology for the last glacial termination: J. Geophys. Res., v. 111, p. D06102. Wang, C., Lee, S.-K., and Enfield, D.B., 2008, Atlantic Warm Pool acting as a link between Atlantic Multidecadal

Frequency of Deep Convective Clouds and Global Warming

Science.gov (United States)

Aumann, Hartmut H.; Teixeira, Joao

2008-01-01

This slide presentation reviews the effect of global warming on the formation of Deep Convective Clouds (DCC). It concludes that nature responds to global warming with an increase in strong convective activity. The frequency of DCC increases with global warming at the rate of 6%/decade. The increased frequency of DCC with global warming alone increases precipitation by 1.7%/decade. It compares the state of the art climate models' response to global warming, and concludes that the parametrization of climate models need to be tuned to more closely emulate the way nature responds to global warming.

Climatic warming increases winter wheat yield but reduces grain nitrogen concentration in east China.

Directory of Open Access Journals (Sweden)

Yunlu Tian

Full Text Available Climatic warming is often predicted to reduce wheat yield and grain quality in China. However, direct evidence is still lacking. We conducted a three-year experiment with a Free Air Temperature Increase (FATI facility to examine the responses of winter wheat growth and plant N accumulation to a moderate temperature increase of 1.5°C predicted to prevail by 2050 in East China. Three warming treatments (AW: all-day warming; DW: daytime warming; NW: nighttime warming were applied for an entire growth period. Consistent warming effects on wheat plant were recorded across the experimental years. An increase of ca. 1.5°C in daily, daytime and nighttime mean temperatures shortened the length of pre-anthesis period averagely by 12.7, 8.3 and 10.7 d (P<0.05, respectively, but had no significant impact on the length of the post-anthesis period. Warming did not significantly alter the aboveground biomass production, but the grain yield was 16.3, 18.1 and 19.6% (P<0.05 higher in the AW, DW and NW plots than the non-warmed plot, respectively. Warming also significantly increased plant N uptake and total biomass N accumulation. However, warming significantly reduced grain N concentrations while increased N concentrations in the leaves and stems. Together, our results demonstrate differential impacts of warming on the depositions of grain starch and protein, highlighting the needs to further understand the mechanisms that underlie warming impacts on plant C and N metabolism in wheat.

Modeling dynamics of tundra plant communities on the Yamal Peninsula, Russia, in response to climate change and grazing pressure

International Nuclear Information System (INIS)

Yu, Q; Epstein, H E; Frost, G V; Walker, D A; Forbes, B C

2011-01-01

Understanding the responses of the arctic tundra biome to a changing climate requires knowledge of the complex interactions among the climate, soils and biological system. This study investigates the individual and interaction effects of climate change and reindeer grazing across a variety of climate zones and soil texture types on tundra vegetation community dynamics using an arctic vegetation model that incorporates the reindeer diet, where grazing is a function of both foliar nitrogen concentration and reindeer forage preference. We found that grazing is important, in addition to the latitudinal climate gradient, in controlling tundra plant community composition, explaining about 13% of the total variance in model simulations for all arctic tundra subzones. The decrease in biomass of lichen, deciduous shrub and graminoid plant functional types caused by grazing is potentially dampened by climate warming. Moss biomass had a nonlinear response to increased grazing intensity, and such responses were stronger when warming was present. Our results suggest that evergreen shrubs may benefit from increased grazing intensity due to their low palatability, yet a growth rate sensitivity analysis suggests that changes in nutrient uptake rates may result in different shrub responses to grazing pressure. Heavy grazing caused plant communities to shift from shrub tundra toward moss, graminoid-dominated tundra in subzones C and D when evergreen shrub growth rates were decreased in the model. The response of moss, lichen and forbs to warming varied across the different subzones. Initial vegetation responses to climate change during transient warming are different from the long term equilibrium responses due to shifts in the controlling mechanisms (nutrient limitation versus competition) within tundra plant communities.

Comparing the sensitivity of permafrost and marine gas hydrate to climate warming

International Nuclear Information System (INIS)

Taylor, A.E.; Dallimore, S.R.; Hyndman, R.D.; Wright, F.

2005-01-01

The sensitivity of Arctic subpermafrost gas hydrate at the Mallik borehole was compared to temperate marine gas hydrate located offshore southwestern Canada. In particular, a finite element geothermal model was used to determine the sensitivity to the end of the ice age, and contemporary climate warming of a 30 m thick methane hydrate layer lying at the base of a gas hydrate stability zone prior to 13.5 kiloannum (ka) before present (BP). It was suggested that the 30 m gas-hydrate-bearing layer would have disappeared by now, according to the thermal signal alone. However, the same gas-hydrate-bearing layer underlying permafrost would persist until at least 4 ka after present, even with contemporary climate warming. The longer time for subpermafrost gas hydrate comes from the thawing pore ice at the base of permafrost, at the expense of dissociation of the deeper gas hydrate. The dissociation of underlying gas hydrate from climate surface warming is buffered by the overlying permafrost

Seasonality of change: Summer warming rates do not fully represent effects of climate change on lake temperatures

Science.gov (United States)

Winslow, Luke; Read, Jordan S.; Hansen, Gretchen J. A.; Rose, Kevin C.; Robertson, Dale M.

2017-01-01

Responses in lake temperatures to climate warming have primarily been characterized using seasonal metrics of surface-water temperatures such as summertime or stratified period average temperatures. However, climate warming may not affect water temperatures equally across seasons or depths. We analyzed a long-term dataset (1981–2015) of biweekly water temperature data in six temperate lakes in Wisconsin, U.S.A. to understand (1) variability in monthly rates of surface- and deep-water warming, (2) how those rates compared to summertime average trends, and (3) if monthly heterogeneity in water temperature trends can be predicted by heterogeneity in air temperature trends. Monthly surface-water temperature warming rates varied across the open-water season, ranging from 0.013 in August to 0.073°C yr−1 in September (standard deviation [SD]: 0.025°C yr−1). Deep-water trends during summer varied less among months (SD: 0.006°C yr−1), but varied broadly among lakes (–0.056°C yr−1 to 0.035°C yr−1, SD: 0.034°C yr−1). Trends in monthly surface-water temperatures were well correlated with air temperature trends, suggesting monthly air temperature trends, for which data exist at broad scales, may be a proxy for seasonal patterns in surface-water temperature trends during the open water season in lakes similar to those studied here. Seasonally variable warming has broad implications for how ecological processes respond to climate change, because phenological events such as fish spawning and phytoplankton succession respond to specific, seasonal temperature cues.

Multi-wheat-model ensemble responses to interannual climatic variability

DEFF Research Database (Denmark)

Ruane, A C; Hudson, N I; Asseng, S

2016-01-01

We compare 27 wheat models' yield responses to interannual climate variability, analyzed at locations in Argentina, Australia, India, and The Netherlands as part of the Agricultural Model Intercomparison and Improvement Project (AgMIP) Wheat Pilot. Each model simulated 1981–2010 grain yield, and ......-term warming, suggesting that additional processes differentiate climate change impacts from observed climate variability analogs and motivating continuing analysis and model development efforts.......We compare 27 wheat models' yield responses to interannual climate variability, analyzed at locations in Argentina, Australia, India, and The Netherlands as part of the Agricultural Model Intercomparison and Improvement Project (AgMIP) Wheat Pilot. Each model simulated 1981–2010 grain yield, and we...... evaluate results against the interannual variability of growing season temperature, precipitation, and solar radiation. The amount of information used for calibration has only a minor effect on most models' climate response, and even small multi-model ensembles prove beneficial. Wheat model clusters reveal...

Amplified Arctic warming by phytoplankton under greenhouse warming.

Science.gov (United States)

Park, Jong-Yeon; Kug, Jong-Seong; Bader, Jürgen; Rolph, Rebecca; Kwon, Minho

2015-05-12

Phytoplankton have attracted increasing attention in climate science due to their impacts on climate systems. A new generation of climate models can now provide estimates of future climate change, considering the biological feedbacks through the development of the coupled physical-ecosystem model. Here we present the geophysical impact of phytoplankton, which is often overlooked in future climate projections. A suite of future warming experiments using a fully coupled ocean-atmosphere model that interacts with a marine ecosystem model reveals that the future phytoplankton change influenced by greenhouse warming can amplify Arctic surface warming considerably. The warming-induced sea ice melting and the corresponding increase in shortwave radiation penetrating into the ocean both result in a longer phytoplankton growing season in the Arctic. In turn, the increase in Arctic phytoplankton warms the ocean surface layer through direct biological heating, triggering additional positive feedbacks in the Arctic, and consequently intensifying the Arctic warming further. Our results establish the presence of marine phytoplankton as an important potential driver of the future Arctic climate changes.

Climate extremes in Europe at 1.5 and 2 degrees of global warming

Science.gov (United States)

King, Andrew D.; Karoly, David J.

2017-11-01

There is an international effort to attempt to limit global warming to 1.5 °C above pre-industrial levels, however, there is a lack of quantitative analysis on the benefits of holding global warming to such a level. In this study, coupled climate model simulations are used to form large ensembles of simulated years at 1.5 °C and 2 °C of global warming. These ensembles are used to assess projected changes in the frequency and magnitude of European climate extremes at these warming levels. For example, we find that events similar to the European record hot summer of 2003, which caused tens of thousands of excess deaths, would be very likely at least 24% less frequent in a world at 1.5 °C global warming compared to 2 °C global warming. Under 2 °C of global warming, we could expect such extreme summer temperatures in the historical record to become commonplace, occurring in at least one-in-every-two years. We find that there are very clear benefits to limiting global warming for the European continent, including fewer and less intense heat and rainfall extremes when compared with higher levels of global warming.

Science, Ethics and the Climate Responsibilities of Industrial Carbon Producers

Science.gov (United States)

Frumhoff, P. C.

2014-12-01

The question of responsibility for climate change lies at the heart of societal debate over actions to curb greenhouse gas emissions and prepare for now unavoidable climate impacts. The UN Framework Convention on Climate Change established the principle of "common but differentiated responsibilities" among nations, signaling the recognition that industrialized nations who had produced the lion's share of historic emissions bore particular responsibility for avoiding dangerous interference with the climate system. But climate responsibilities can be distributed in other ways as well. This talk focuses on the scientific, historical and ethical basis for considering the climate responsibilities of the major fossil energy companies that have produced and marketed the coal, oil and natural gas whose use largely drives global warming, often while investing in efforts to discredit the scientific evidence and prevent policies that would encourage a transition to low-carbon energy. Earth scientists and scientific societies who rely on financial support from these companies have an opportunity to consider what ethical stance they might take to align their research, scientific understanding and values.

How Will Climate Warming Affect Non-Native Pumpkinseed Lepomis gibbosus Populations in the U.K.?

Directory of Open Access Journals (Sweden)

Grzegorz Zięba

Full Text Available Of the non-native fishes introduced to the U.K., the pumpkinseed is one of six species predicted to benefit from the forecasted climate warming conditions. To demonstrate the potential response of adults and their progeny to a water temperature increase, investigations of parental pumpkinseed acclimatization, reproduction and YOY over-wintering were carried out in outdoor experimental ponds under ambient and elevated water temperature regimes. No temperature effects were observed on either adult survivorship and growth, and none of the assessed reproductive activity variables (total spawning time, spawning season length, number of spawning bouts appeared to be responsible for the large differences observed in progeny number and biomass. However, it was demonstrated in a previous study [Zięba G. et al., 2010] that adults in the heated ponds began spawning earlier than those of the ambient ponds. Ambient ponds produced 2.8× more progeny than the heated ponds, but these progeny were significantly smaller, probably due to their late hatching date, and subsequently suffered very high mortality over the first winter. Pumpkinseed in the U.K. will clearly benefit from climate warming through earlier seasonal reproduction, resulting in larger progeny going into winter, and as a result, higher over-winter survivorship would be expected relative to that which occurs under the present climatic regime.

Potential Distribution Predicted for Rhynchophorus ferrugineus in China under Different Climate Warming Scenarios.

Directory of Open Access Journals (Sweden)

Xuezhen Ge

Full Text Available As the primary pest of palm trees, Rhynchophorus ferrugineus (Olivier (Coleoptera: Curculionidae has caused serious harm to palms since it first invaded China. The present study used CLIMEX 1.1 to predict the potential distribution of R. ferrugineus in China according to both current climate data (1981-2010 and future climate warming estimates based on simulated climate data for the 2020s (2011-2040 provided by the Tyndall Center for Climate Change Research (TYN SC 2.0. Additionally, the Ecoclimatic Index (EI values calculated for different climatic conditions (current and future, as simulated by the B2 scenario were compared. Areas with a suitable climate for R. ferrugineus distribution were located primarily in central China according to the current climate data, with the northern boundary of the distribution reaching to 40.1°N and including Tibet, north Sichuan, central Shaanxi, south Shanxi, and east Hebei. There was little difference in the potential distribution predicted by the four emission scenarios according to future climate warming estimates. The primary prediction under future climate warming models was that, compared with the current climate model, the number of highly favorable habitats would increase significantly and expand into northern China, whereas the number of both favorable and marginally favorable habitats would decrease. Contrast analysis of EI values suggested that climate change and the density of site distribution were the main effectors of the changes in EI values. These results will help to improve control measures, prevent the spread of this pest, and revise the targeted quarantine areas.

Influences of spawning timing, water temperature, and climatic warming on early life history phenology in western Alaska sockeye salmon

Science.gov (United States)

Sparks, Morgan M.; Falke, Jeffrey A.; Quinn, Thomas P.; Adkison, Milo D.; Schindler, Daniel E.; Bartz, Krista K.; Young, Daniel B.; Westley, Peter A. H.

2018-01-01

We applied an empirical model to predict hatching and emergence timing for 25 western Alaska sockeye salmon (Oncorhynchus nerka) populations in four lake-nursery systems to explore current patterns and potential responses of early life history phenology to warming water temperatures. Given experienced temperature regimes during development, we predicted hatching to occur in as few as 58 d to as many as 260 d depending on spawning timing and temperature. For a focal lake spawning population, our climate-lake temperature model predicted a water temperature increase of 0.7 to 1.4 °C from 2015 to 2099 during the incubation period, which translated to a 16 d to 30 d earlier hatching timing. The most extreme scenarios of warming advanced development by approximately a week earlier than historical minima and thus climatic warming may lead to only modest shifts in phenology during the early life history stage of this population. The marked variation in the predicted timing of hatching and emergence among populations in close proximity on the landscape may serve to buffer this metapopulation from climate change.

Disentangling the effects of a century of eutrophication and climate warming on freshwater lake fish assemblages.

Directory of Open Access Journals (Sweden)

Peter C Jacobson

Full Text Available Eutrophication and climate warming are profoundly affecting fish in many freshwater lakes. Understanding the specific effects of these stressors is critical for development of effective adaptation and remediation strategies for conserving fish populations in a changing environment. Ecological niche models that incorporated the individual effects of nutrient concentration and climate were developed for 25 species of fish sampled in standard gillnet surveys from 1,577 Minnesota lakes. Lake phosphorus concentrations and climates were hindcasted to a pre-disturbance period of 1896-1925 using existing land use models and historical temperature data. Then historical fish assemblages were reconstructed using the ecological niche models. Substantial changes were noted when reconstructed fish assemblages were compared to those from the contemporary period (1981-2010. Disentangling the sometimes opposing, sometimes compounding, effects of eutrophication and climate warming was critical for understanding changes in fish assemblages. Reconstructed abundances of eutrophication-tolerant, warmwater taxa increased in prairie lakes that experienced significant eutrophication and climate warming. Eutrophication-intolerant, warmwater taxa abundance increased in forest lakes where primarily climate warming was the stressor. Coolwater fish declined in abundance in both ecoregions. Large changes in modeled abundance occurred when the effects of both climate and eutrophication operated in the same direction for some species. Conversely, the effects of climate warming and eutrophication operated in opposing directions for other species and dampened net changes in abundance. Quantifying the specific effects of climate and eutrophication will allow water resource managers to better understand how lakes have changed and provide expectations for sustainable fish assemblages in the future.

Fungi regulate response of N2O production to warming and grazing in a Tibetan grassland

Science.gov (United States)

Zhong, Lei; Wang, Shiping; Xu, Xingliang; Wang, Yanfen; Rui, Yichao; Zhou, Xiaoqi; Shen, Qinhua; Wang, Jinzhi; Jiang, Lili; Luo, Caiyun; Gu, Tianbao; Ma, Wenchao; Chen, Guanyi

2018-03-01

Lack of understanding of the effects of warming and winter grazing on soil fungal contribution to nitrous oxide (N2O) production has limited our ability to predict N2O fluxes under changes in climate and land use management, because soil fungi play an important role in driving terrestrial N cycling. Here, we examined the effects of 10 years' warming and winter grazing on soil N2O emissions potential in an alpine meadow. Our results showed that soil bacteria and fungi contributed 46 % and 54 % to nitrification, and 37 % and 63 % to denitrification, respectively. Neither warming nor winter grazing affected the activity of enzymes responsible for overall nitrification and denitrification. However, warming significantly increased the enzyme activity of bacterial nitrification and denitrification to 53 % and 55 %, respectively. Warming significantly decreased enzyme activity of fungal nitrification and denitrification to 47 % and 45 %, respectively, while winter grazing had no such effect. We conclude that soil fungi could be the main source for N2O production potential in the Tibetan alpine grasslands. Warming and winter grazing may not affect the potential for soil N2O production potential, but climate warming can alter biotic pathways responsible for N2O production. These findings indicate that characterizing how fungal nitrification/denitrification contributes to N2O production, as well as how it responds to environmental and land use changes, can advance our understanding of N cycling. Therefore, our results provide some new insights about ecological controls on N2O production and lead to refine greenhouse gas flux models.

The interplay between knowledge, perceived efficacy, and concern about global warming and climate change: a one-year longitudinal study.

Science.gov (United States)

Milfont, Taciano L

2012-06-01

If the long-term goal of limiting warming to less than 2°C is to be achieved, rapid and sustained reductions of greenhouse gas emissions are required. These reductions will demand political leadership and widespread public support for action on global warming and climate change. Public knowledge, level of concern, and perceived personal efficacy, in positively affecting these issues are key variables in understanding public support for mitigation action. Previous research has documented some contradictory associations between knowledge, personal efficacy, and concern about global warming and climate change, but these cross-sectional findings limit inferences about temporal stability and direction of influence. This study examines the relationships between these three variables over a one-year period and three waves with national data from New Zealand. Results showed a positive association between the variables, and the pattern of findings was stable and consistent across the three data points. More importantly, results indicate that concern mediates the influence of knowledge on personal efficacy. Knowing more about global warming and climate change increases overall concern about the risks of these issues, and this increased concern leads to greater perceived efficacy and responsibility to help solving them. Implications for risk communication are discussed. © 2012 Society for Risk Analysis.

Warm Rain Processes Over the Tropical Oceans and Implications on Climate Change

Science.gov (United States)

Lau, William K. M.; Wu, H. T.

2004-01-01

In this talk, we will first show results from TRMM regarding the characteristics of warm rains over the tropical oceans, and the dependence of rate of warm rain production on sea surface temperature. Results lead to the hypothesis that warm rain production efficiency, i.e., autoconversion, may be increased in a warm climate. We use the GEOS-II GCM to test this hypothesis. Our modeling results show that in a climate with increased rate of autoconversion, the total rain amount is increased, with warm rain contributing to a larger portion of the increase. The abundant rainout of warm precipitation at middle to low levels causes a reduction of high cloud cover due to the depletion of water available for ice-phase rain production. As a result, more isolated, but more intense penetrative convection develops. Results also show that increased autoconversion reduces the convective adjustment time scale tends, implying a faster recycling of atmospheric water. Most interestingly, the increased low level heating associated with warm rain leads to more energetic Madden and Julian oscillations in the tropics, with well-defined eastward propagation. While reducing the autoconversion leads to an abundant mix of westward and eastward tropical disturbance on daily to weekly time scales. The causes of the sensitivity of the dynamical regimes to the microphysics parameterization in the GCM will be discussed.

Climate warming could increase recruitment success in glacier foreland plants.

Science.gov (United States)

Mondoni, Andrea; Pedrini, Simone; Bernareggi, Giulietta; Rossi, Graziano; Abeli, Thomas; Probert, Robin J; Ghitti, Michele; Bonomi, Costantino; Orsenigo, Simone

2015-11-01

Glacier foreland plants are highly threatened by global warming. Regeneration from seeds on deglaciated terrain will be crucial for successful migration and survival of these species, and hence a better understanding of the impacts of climate change on seedling recruitment is urgently needed to predict future plant persistence in these environments. This study presents the first field evidence of the impact of climate change on recruitment success of glacier foreland plants. Seeds of eight foreland species were sown on a foreland site at 2500 m a.s.l., and at a site 400 m lower in altitude to simulate a 2·7 °C increase in mean annual temperature. Soil from the site of origin was used to reproduce the natural germination substrate. Recruitment success, temperature and water potential were monitored for 2 years. The response of seed germination to warming was further investigated in the laboratory. At the glacier foreland site, seedling emergence was low (0 to approx. 40 %) and occurred in summer in all species after seeds had experienced autumn and winter seasons. However, at the warmer site there was a shift from summer to autumn emergence in two species and a significant increase of summer emergence (13-35 % higher) in all species except two. Survival and establishment was possible for 60-75 % of autumn-emerged seedlings and was generally greater under warmer conditions. Early snowmelt in spring caused the main ecological factors enhancing the recruitment success. The results suggest that warming will influence the recruitment of glacier foreland species primarily via the extension of the snow-free period in spring, which increases seedling establishment and results in a greater resistance to summer drought and winter extremes. The changes in recruitment success observed here imply that range shifts or changes in abundance are possible in a future warmer climate, but overall success may be dependent on interactions with shifts in other components of the

Astrochronology of extreme global warming events during the early Eocene greenhouse climate

NARCIS (Netherlands)

Lauretano, V.

2016-01-01

The early Eocene represents an ideal case study to analyse the impact of enhanced global warming on the ocean-atmosphere system and the relationship between carbon cycling and climate. During this time interval, the Earth’s surface experienced a long-term warming trend that culminated in a period of

Temperature extremes in Europe: mechanisms and responses to climatic change

International Nuclear Information System (INIS)

Cattiaux, Julien

2010-01-01

Europe witnessed a spate of record-breaking warm seasons during the 2000's. As illustrated by the devastating heat-wave of the summer 2003, these episodes induced strong societal and environmental impacts. Such occurrence of exceptional events over a relatively short time period raised up many questionings in the present context of climate change. In particular, can recent temperature extremes be considered as 'previews' of future climate conditions? Do they result from an increasing temperature variability? These questions constitute the main motivations of this thesis. Thus, our work aims to contribute to the understanding of physical mechanisms responsible for seasonal temperature extremes in Europe, in order to anticipate their future statistical characteristics. Involved processes are assessed by both statistical data-analysis of observations and climate projections and regional modeling experiments. First we show that while the inter-annual European temperature variability appears driven by disturbances in the North-Atlantic dynamics, the recent warming is likely to be dissociated with potential circulation changes. This inconsistency climaxes during the exceptionally mild autumn of 2006, whose temperature anomaly is only half explained by the atmospheric flow. Recent warm surface conditions in the North-Atlantic ocean seem to substantially contribute to the European warming in autumn-winter, through the establishment of advective and radiative processes. In spring-summer, since both advection by the westerlies and Atlantic warming are reduced, more local processes appear predominant (e.g. soil moisture, clouds, aerosols). Then the issue of future evolution of the relationship between North-Atlantic dynamics and European temperatures is addressed, based on climate projections of the International Panel on Climate Change. Multi-model analysis, using both flow-analogues and weather regimes methods, show that the inconsistency noticed over recent decades is

Conservation Planning for Coral Reefs Accounting for Climate Warming Disturbances.

Directory of Open Access Journals (Sweden)

Rafael A Magris

Full Text Available Incorporating warming disturbances into the design of marine protected areas (MPAs is fundamental to developing appropriate conservation actions that confer coral reef resilience. We propose an MPA design approach that includes spatially- and temporally-varying sea-surface temperature (SST data, integrating both observed (1985-2009 and projected (2010-2099 time-series. We derived indices of acute (time under reduced ecosystem function following short-term events and chronic thermal stress (rate of warming and combined them to delineate thermal-stress regimes. Coral reefs located on the Brazilian coast were used as a case study because they are considered a conservation priority in the southwestern Atlantic Ocean. We show that all coral reef areas in Brazil have experienced and are projected to continue to experience chronic warming, while acute events are expected to increase in frequency and intensity. We formulated quantitative conservation objectives for regimes of thermal stress. Based on these objectives, we then evaluated if/how they are achieved in existing Brazilian MPAs and identified priority areas where additional protection would reinforce resilience. Our results show that, although the current system of MPAs incorporates locations within some of our thermal-stress regimes, historical and future thermal refugia along the central coast are completely unprotected. Our approach is applicable to other marine ecosystems and adds to previous marine planning for climate change in two ways: (i by demonstrating how to spatially configure MPAs that meet conservation objectives for warming disturbance using spatially- and temporally-explicit data; and (ii by strategically allocating different forms of spatial management (MPA types intended to mitigate warming impacts and also enhance future resistance to climate warming.

The reef-building coral Siderastrea siderea exhibits parabolic responses to ocean acidification and warming.

Science.gov (United States)

Castillo, Karl D; Ries, Justin B; Bruno, John F; Westfield, Isaac T

2014-12-22

Anthropogenic increases in atmospheric CO2 over this century are predicted to cause global average surface ocean pH to decline by 0.1-0.3 pH units and sea surface temperature to increase by 1-4°C. We conducted controlled laboratory experiments to investigate the impacts of CO2-induced ocean acidification (pCO2 = 324, 477, 604, 2553 µatm) and warming (25, 28, 32°C) on the calcification rate of the zooxanthellate scleractinian coral Siderastrea siderea, a widespread, abundant and keystone reef-builder in the Caribbean Sea. We show that both acidification and warming cause a parabolic response in the calcification rate within this coral species. Moderate increases in pCO2 and warming, relative to near-present-day values, enhanced coral calcification, with calcification rates declining under the highest pCO2 and thermal conditions. Equivalent responses to acidification and warming were exhibited by colonies across reef zones and the parabolic nature of the corals' response to these stressors was evident across all three of the experiment's 30-day observational intervals. Furthermore, the warming projected by the Intergovernmental Panel on Climate Change for the end of the twenty-first century caused a fivefold decrease in the rate of coral calcification, while the acidification projected for the same interval had no statistically significant impact on the calcification rate-suggesting that ocean warming poses a more immediate threat than acidification for this important coral species.

Climate warming feedback from mountain birch forest expansion: reduced albedo dominates carbon uptake.

Science.gov (United States)

de Wit, Heleen A; Bryn, Anders; Hofgaard, Annika; Karstensen, Jonas; Kvalevåg, Maria M; Peters, Glen P

2014-07-01

Expanding high-elevation and high-latitude forest has contrasting climate feedbacks through carbon sequestration (cooling) and reduced surface reflectance (warming), which are yet poorly quantified. Here, we present an empirically based projection of mountain birch forest expansion in south-central Norway under climate change and absence of land use. Climate effects of carbon sequestration and albedo change are compared using four emission metrics. Forest expansion was modeled for a projected 2.6 °C increase in summer temperature in 2100, with associated reduced snow cover. We find that the current (year 2000) forest line of the region is circa 100 m lower than its climatic potential due to land-use history. In the future scenarios, forest cover increased from 12% to 27% between 2000 and 2100, resulting in a 59% increase in biomass carbon storage and an albedo change from 0.46 to 0.30. Forest expansion in 2100 was behind its climatic potential, forest migration rates being the primary limiting factor. In 2100, the warming caused by lower albedo from expanding forest was 10 to 17 times stronger than the cooling effect from carbon sequestration for all emission metrics considered. Reduced snow cover further exacerbated the net warming feedback. The warming effect is considerably stronger than previously reported for boreal forest cover, because of the typically low biomass density in mountain forests and the large changes in albedo of snow-covered tundra areas. The positive climate feedback of high-latitude and high-elevation expanding forests with seasonal snow cover exceeds those of afforestation at lower elevation, and calls for further attention of both modelers and empiricists. The inclusion and upscaling of these climate feedbacks from mountain forests into global models is warranted to assess the potential global impacts. © 2013 John Wiley & Sons Ltd.

Free boundary models for mosquito range movement driven by climate warming.

Science.gov (United States)

Bao, Wendi; Du, Yihong; Lin, Zhigui; Zhu, Huaiping

2018-03-01

As vectors, mosquitoes transmit numerous mosquito-borne diseases. Among the many factors affecting the distribution and density of mosquitoes, climate change and warming have been increasingly recognized as major ones. In this paper, we make use of three diffusive logistic models with free boundary in one space dimension to explore the impact of climate warming on the movement of mosquito range. First, a general model incorporating temperature change with location and time is introduced. In order to gain insights of the model, a simplified version of the model with the change of temperature depending only on location is analyzed theoretically, for which the dynamical behavior is completely determined and presented. The general model can be modified into a more realistic one of seasonal succession type, to take into account of the seasonal changes of mosquito movements during each year, where the general model applies only for the time period of the warm seasons of the year, and during the cold season, the mosquito range is fixed and the population is assumed to be in a hibernating status. For both the general model and the seasonal succession model, our numerical simulations indicate that the long-time dynamical behavior is qualitatively similar to the simplified model, and the effect of climate warming on the movement of mosquitoes can be easily captured. Moreover, our analysis reveals that hibernating enhances the chances of survival and successful spreading of the mosquitoes, but it slows down the spreading speed.

Global warming and climate change in Amazonia: Climate-vegetation feedback and impacts on water resources

Science.gov (United States)

Marengo, José; Nobre, Carlos A.; Betts, Richard A.; Cox, Peter M.; Sampaio, Gilvan; Salazar, Luis

This chapter constitutes an updated review of long-term climate variability and change in the Amazon region, based on observational data spanning more than 50 years of records and on climate-change modeling studies. We start with the early experiments on Amazon deforestation in the late 1970s, and the evolution of these experiments to the latest studies on greenhouse gases emission scenarios and land use changes until the end of the twenty-first century. The "Amazon dieback" simulated by the HadCM3 model occurs after a "tipping point" of CO2 concentration and warming. Experiments on Amazon deforestation and change of climate suggest that once a critical deforestation threshold (or tipping point) of 40-50% forest loss is reached in eastern Amazonia, climate would change in a way which is dangerous for the remaining forest. This may favor a collapse of the tropical forest, with a substitution of the forest by savanna-type vegetation. The concept of "dangerous climate change," as a climate change, which induces positive feedback, which accelerate the change, is strongly linked to the occurrence of tipping points, and it can be explained as the presence of feedback between climate change and the carbon cycle, particularly involving a weakening of the current terrestrial carbon sink and a possible reversal from a sink (as in present climate) to a source by the year 2050. We must, therefore, currently consider the drying simulated by the Hadley Centre model(s) as having a finite probability under global warming, with a potentially enormous impact, but with some degree of uncertainty.

Unexpected Impacts of Global warming on Extreme Warm Spells

Science.gov (United States)

Sardeshmukh, P. D.; Compo, G. P.; McColl, C.; Penland, C.

2017-12-01

It is generally presumed that the likelihood of extreme warm spells around the globe has increased, and will continue to increase, due to global warming. However, we find that this is generally not true in three very different types of global observational datasets and uncoupled atmospheric model simulations of the 1959 to 2012 period with prescribed observed global SSTs, sea ice, and radiative forcing changes. While extreme warm spells indeed became more common in many regions, in many other regions their likelihood remained almost the same or even decreased from the first half to the second half of this period. Such regions of unexpected changes covered nearly 40 percent of the globe in both winter and summer. The basic reason for this was a decrease of temperature variability in such regions that offset or even negated the effect of the mean temperature shift on extreme warm spell probabilities. The possibility of such an impact on extreme value probabilities was highlighted in a recent paper by Sardeshmukh, Compo, and Penland (Journal of Climate 2015). The consistency of the changes in extreme warm spell probabilities among the different observational datasets and model simulations examined suggests that they are robust regional aspects of global warming associated with atmospheric circulation changes. This highlights the need for climate models to represent not just the mean regional temperature signals but also the changes in subseasonal temperature variability associated with global warming. However, current climate models (both CMIP3 and CMIP5) generally underestimate the magnitude of the changes in the atmospheric circulation and associated temperature variability. A likely major cause of this is their continuing underestimation of the magnitude of the spatial variation of tropical SST trends. By generating an overly spatially bland tropical SST warming in response to changes in radiative forcing, the models spuriously mute tropically

Global warming not so harmful for all plants-response of holomycotrophic orchid species for the future climate change

Czech Academy of Sciences Publication Activity Database

Kolanowska, Marta; Kras, M.; Lipińska, M.; Mystkowska, K.; Szlachetko, D. L.; Naczk, A. M.

2017-01-01

Roč. 7, č. 1 (2017), č. článku 12704. ISSN 2045-2322 R&D Projects: GA ČR GB14-36098G Institutional support: RVO:86652079 Keywords : global warming * Orchids * climate change Subject RIV: EH - Ecology, Behaviour OBOR OECD: Environmental sciences (social aspects to be 5.7) Impact factor: 4.259, year: 2016

Climate impacts on human livelihoods at 1.5° and 2° of warming

Science.gov (United States)

Lissner, Tabea

2017-04-01

The measurement of impacts of climate change on socio-economic systems remains challenging and especially multi-dimensional outcome measures remain scarce. Climate impacts can directly affect many dimensions of human livelihoods, which cannot be addressed by monetary assessments alone. Multi-dimensional measures are essential in order to understand the full range of consequences of climate change and to understand the costs that higher levels of warming may have, not only in economic terms, but also in terms of non-market impacts on human livelihood. The AHEAD framework aims at measuring "Adequate Human livelihood conditions for wEll-being And Development" in a multi-dimensional framework, allowing to focus on resources and conditions which are a requirement to attain well-being. In this contribution we build on previous implementations of AHEAD and focus on differences in climate impacts at 1.5° and 2° of warming in order to improve our understanding of the societal consequences of these different warming levels.

Winter Season Mortality: Will Climate Warming Bring Benefits?

Science.gov (United States)

Kinney, Patrick L; Schwartz, Joel; Pascal, Mathilde; Petkova, Elisaveta; Tertre, Alain Le; Medina, Sylvia; Vautard, Robert

2015-06-01

Extreme heat events are associated with spikes in mortality, yet death rates are on average highest during the coldest months of the year. Under the assumption that most winter excess mortality is due to cold temperature, many previous studies have concluded that winter mortality will substantially decline in a warming climate. We analyzed whether and to what extent cold temperatures are associated with excess winter mortality across multiple cities and over multiple years within individual cities, using daily temperature and mortality data from 36 US cities (1985-2006) and 3 French cities (1971-2007). Comparing across cities, we found that excess winter mortality did not depend on seasonal temperature range, and was no lower in warmer vs. colder cities, suggesting that temperature is not a key driver of winter excess mortality. Using regression models within monthly strata, we found that variability in daily mortality within cities was not strongly influenced by winter temperature. Finally we found that inadequate control for seasonality in analyses of the effects of cold temperatures led to spuriously large assumed cold effects, and erroneous attribution of winter mortality to cold temperatures. Our findings suggest that reductions in cold-related mortality under warming climate may be much smaller than some have assumed. This should be of interest to researchers and policy makers concerned with projecting future health effects of climate change and developing relevant adaptation strategies.

Annual Removal of Aboveground Plant Biomass Alters Soil Microbial Responses to Warming

Directory of Open Access Journals (Sweden)

Kai Xue

2016-09-01

Full Text Available Clipping (i.e., harvesting aboveground plant biomass is common in agriculture and for bioenergy production. However, microbial responses to clipping in the context of climate warming are poorly understood. We investigated the interactive effects of grassland warming and clipping on soil properties and plant and microbial communities, in particular, on microbial functional genes. Clipping alone did not change the plant biomass production, but warming and clipping combined increased the C4 peak biomass by 47% and belowground net primary production by 110%. Clipping alone and in combination with warming decreased the soil carbon input from litter by 81% and 75%, respectively. With less carbon input, the abundances of genes involved in degrading relatively recalcitrant carbon increased by 38% to 137% in response to either clipping or the combined treatment, which could weaken long-term soil carbon stability and trigger positive feedback with respect to warming. Clipping alone also increased the abundance of genes for nitrogen fixation, mineralization, and denitrification by 32% to 39%. Such potentially stimulated nitrogen fixation could help compensate for the 20% decline in soil ammonium levels caused by clipping alone and could contribute to unchanged plant biomass levels. Moreover, clipping tended to interact antagonistically with warming, especially with respect to effects on nitrogen cycling genes, demonstrating that single-factor studies cannot predict multifactorial changes. These results revealed that clipping alone or in combination with warming altered soil and plant properties as well as the abundance and structure of soil microbial functional genes. Aboveground biomass removal for biofuel production needs to be reconsidered, as the long-term soil carbon stability may be weakened.

Midlatitude atmospheric circulation responses under 1.5 and 2.0 °C warming and implications for regional impacts

Science.gov (United States)

Li, Camille; Michel, Clio; Seland Graff, Lise; Bethke, Ingo; Zappa, Giuseppe; Bracegirdle, Thomas J.; Fischer, Erich; Harvey, Ben J.; Iversen, Trond; King, Martin P.; Krishnan, Harinarayan; Lierhammer, Ludwig; Mitchell, Daniel; Scinocca, John; Shiogama, Hideo; Stone, Dáithí A.; Wettstein, Justin J.

2018-04-01

This study investigates the global response of the midlatitude atmospheric circulation to 1.5 and 2.0 °C of warming using the HAPPI (Half a degree Additional warming, Prognosis and Projected Impacts) ensemble, with a focus on the winter season. Characterising and understanding this response is critical for accurately assessing the near-term regional impacts of climate change and the benefits of limiting warming to 1.5 °C above pre-industrial levels, as advocated by the Paris Agreement of the United Nations Framework Convention on Climate Change (UNFCCC). The HAPPI experimental design allows an assessment of uncertainty in the circulation response due to model dependence and internal variability. Internal variability is found to dominate the multi-model mean response of the jet streams, storm tracks, and stationary waves across most of the midlatitudes; larger signals in these features are mostly consistent with those seen in more strongly forced warming scenarios. Signals that emerge in the 1.5 °C experiment are a weakening of storm activity over North America, an inland shift of the North American stationary ridge, an equatorward shift of the North Pacific jet exit, and an equatorward intensification of the South Pacific jet. Signals that emerge under an additional 0.5 °C of warming include a poleward shift of the North Atlantic jet exit, an eastward extension of the North Atlantic storm track, and an intensification on the flanks of the Southern Hemisphere storm track. Case studies explore the implications of these circulation responses for precipitation impacts in the Mediterranean, in western Europe, and on the North American west coast, paying particular attention to possible outcomes at the tails of the response distributions. For example, the projected weakening of the Mediterranean storm track emerges in the 2 °C warmer world, with exceptionally dry decades becoming 5 times more likely.

Assessing forest vulnerability to climate warming using a process-based model of tree growth: bad prospects for rear-edges.

Science.gov (United States)

Sánchez-Salguero, Raúl; Camarero, Jesus Julio; Gutiérrez, Emilia; González Rouco, Fidel; Gazol, Antonio; Sangüesa-Barreda, Gabriel; Andreu-Hayles, Laia; Linares, Juan Carlos; Seftigen, Kristina

2017-07-01

Growth models can be used to assess forest vulnerability to climate warming. If global warming amplifies water deficit in drought-prone areas, tree populations located at the driest and southernmost distribution limits (rear-edges) should be particularly threatened. Here, we address these statements by analyzing and projecting growth responses to climate of three major tree species (silver fir, Abies alba; Scots pine, Pinus sylvestris; and mountain pine, Pinus uncinata) in mountainous areas of NE Spain. This region is subjected to Mediterranean continental conditions, it encompasses wide climatic, topographic and environmental gradients, and, more importantly, it includes rear-edges of the continuous distributions of these tree species. We used tree-ring width data from a network of 110 forests in combination with the process-based Vaganov-Shashkin-Lite growth model and climate-growth analyses to forecast changes in tree growth during the 21st century. Climatic projections were based on four ensembles CO 2 emission scenarios. Warm and dry conditions during the growing season constrain silver fir and Scots pine growth, particularly at the species rear-edge. By contrast, growth of high-elevation mountain pine forests is enhanced by climate warming. The emission scenario (RCP 8.5) corresponding to the most pronounced warming (+1.4 to 4.8 °C) forecasted mean growth reductions of -10.7% and -16.4% in silver fir and Scots pine, respectively, after 2050. This indicates that rising temperatures could amplify drought stress and thus constrain the growth of silver fir and Scots pine rear-edge populations growing at xeric sites. Contrastingly, mountain pine growth is expected to increase by +12.5% due to a longer and warmer growing season. The projections of growth reduction in silver fir and Scots pine portend dieback and a contraction of their species distribution areas through potential local extinctions of the most vulnerable driest rear-edge stands. Our modeling

Response of the North Atlantic surface and intermediate ocean structure to climate warming of MIS 11.

Science.gov (United States)

Kandiano, Evgenia S; van der Meer, Marcel T J; Schouten, Stefan; Fahl, Kirsten; Sinninghe Damsté, Jaap S; Bauch, Henning A

2017-04-10

Investigating past interglacial climates not only help to understand how the climate system operates in general, it also forms a vital basis for climate predictions. We reconstructed vertical stratification changes in temperature and salinity in the North Atlantic for a period some 400 ka ago (MIS11), an interglacial time analogue of a future climate. As inferred from a unique set of biogeochemical, geochemical, and faunal data, the internal upper ocean stratification across MIS 11 shows distinct depth-dependent dynamical changes related to vertical as well as lateral shifts in the upper Atlantic meridional circulation system. Importantly, transient cold events are recognized near the end of the long phase of postglacial warming at surface, subsurface, mid, and deeper water layers. These data demonstrate that MIS 11 coolings over the North Atlantic were initially triggered by freshwater input at the surface and expansion of cold polar waters into the Subpolar Gyre. The cooling signal was then transmitted downwards into mid-water depths. Since the cold events occurred after the main deglacial phase we suggest that their cause might be related to continuous melting of the Greenland ice sheet, a mechanism that might also be relevant for the present and upcoming climate.

The Effect of Urban Heat Island on Climate Warming in the Yangtze River Delta Urban Agglomeration in China

Directory of Open Access Journals (Sweden)

Qunfang Huang

2015-07-01

Full Text Available The Yangtze River Delta (YRD has experienced rapid urbanization and dramatic economic development since 1978 and the Yangtze River Delta urban agglomeration (YRDUA has been one of the three largest urban agglomerations in China. We present evidence of a significant urban heat island (UHI effect on climate warming based on an analysis of the impacts of the urbanization rate, urban population, and land use changes on the warming rate of the daily average, minimal (nighttime and maximal (daytime air temperature in the YRDUA using 41 meteorological stations observation data. The effect of the UHI on climate warming shows a large spatial variability. The average warming rates of average air temperature of huge cities, megalopolises, large cities, medium-sized cities, and small cities are 0.483, 0.314 ± 0.030, 0.282 ± 0.042, 0.225 ± 0.044 and 0.179 ± 0.046 °C/decade during the period of 1957–2013, respectively. The average warming rates of huge cities and megalopolises are significantly higher than those of medium-sized cities and small cities, indicating that the UHI has a significant effect on climate warming (t-test, p < 0.05. Significantly positive correlations are found between the urbanization rate, population, built-up area and warming rate of average air temperature (p < 0.001. The average warming rate of average air temperature attributable to urbanization is 0.124 ± 0.074 °C/decade in the YRDUA. Urbanization has a measurable effect on the observed climate warming in the YRD aggravating the global climate warming.

20th century climate warming and tree-limit rise in the southern Scandes of Sweden.

Science.gov (United States)

Kullman, L

2001-03-01

Climate warming by ca. 0.8 degree C between the late-19th and late-20th century, although with some fluctuations, has forced multispecies elevational tree-limit advance by > 100 m for the principal tree species in the Swedish part of the Scandinavian mountain range. Predominantly, these processes imply growth in height of old-established individuals and less frequently upslope migration of new individuals. After a slight retardation during some cooler decades after 1940, a new active phase of tree-limit advance has occurred with a series of exceptionally mild winters and some warm summers during the 1990s. The magnitude of total 20th century tree-limit rise varies with topoclimate and is mainly confined to wind-sheltered and snow-rich segments of the landscape. Thickening of birch tree stands in the "advance belt" has profoundly altered the general character of the subalpine/low alpine landscape and provides a positive feedback loop for further progressive change and resilience to short-term cooling episodes. All upslope tree-limit shifts and associated landscape transformations during the 20th century have occurred without appreciable time lags, which constitutes knowledge fundamental to the generation of realistic models concerning vegetation responses to potential future warming. The new and elevated pine tree-limit may be the highest during the past 4000 14C years. Thus, it is tentatively inferred that the 20th century climate is unusually warm in a late-Holocene perspective.

Global warming precipitation accumulation increases above the current-climate cutoff scale.

Science.gov (United States)

Neelin, J David; Sahany, Sandeep; Stechmann, Samuel N; Bernstein, Diana N

2017-02-07

Precipitation accumulations, integrated over rainfall events, can be affected by both intensity and duration of the storm event. Thus, although precipitation intensity is widely projected to increase under global warming, a clear framework for predicting accumulation changes has been lacking, despite the importance of accumulations for societal impacts. Theory for changes in the probability density function (pdf) of precipitation accumulations is presented with an evaluation of these changes in global climate model simulations. We show that a simple set of conditions implies roughly exponential increases in the frequency of the very largest accumulations above a physical cutoff scale, increasing with event size. The pdf exhibits an approximately power-law range where probability density drops slowly with each order of magnitude size increase, up to a cutoff at large accumulations that limits the largest events experienced in current climate. The theory predicts that the cutoff scale, controlled by the interplay of moisture convergence variance and precipitation loss, tends to increase under global warming. Thus, precisely the large accumulations above the cutoff that are currently rare will exhibit increases in the warmer climate as this cutoff is extended. This indeed occurs in the full climate model, with a 3 °C end-of-century global-average warming yielding regional increases of hundreds of percent to >1,000% in the probability density of the largest accumulations that have historical precedents. The probabilities of unprecedented accumulations are also consistent with the extension of the cutoff.

Global warming precipitation accumulation increases above the current-climate cutoff scale

Science.gov (United States)

Sahany, Sandeep; Stechmann, Samuel N.; Bernstein, Diana N.

2017-01-01

Precipitation accumulations, integrated over rainfall events, can be affected by both intensity and duration of the storm event. Thus, although precipitation intensity is widely projected to increase under global warming, a clear framework for predicting accumulation changes has been lacking, despite the importance of accumulations for societal impacts. Theory for changes in the probability density function (pdf) of precipitation accumulations is presented with an evaluation of these changes in global climate model simulations. We show that a simple set of conditions implies roughly exponential increases in the frequency of the very largest accumulations above a physical cutoff scale, increasing with event size. The pdf exhibits an approximately power-law range where probability density drops slowly with each order of magnitude size increase, up to a cutoff at large accumulations that limits the largest events experienced in current climate. The theory predicts that the cutoff scale, controlled by the interplay of moisture convergence variance and precipitation loss, tends to increase under global warming. Thus, precisely the large accumulations above the cutoff that are currently rare will exhibit increases in the warmer climate as this cutoff is extended. This indeed occurs in the full climate model, with a 3 °C end-of-century global-average warming yielding regional increases of hundreds of percent to >1,000% in the probability density of the largest accumulations that have historical precedents. The probabilities of unprecedented accumulations are also consistent with the extension of the cutoff. PMID:28115693

Quantifying the Influence of Global Warming on Unprecedented Extreme Climate Events

Science.gov (United States)

Diffenbaugh, Noah S.; Singh, Deepti; Mankin, Justin S.; Horton, Daniel E.; Swain, Daniel L.; Touma, Danielle; Charland, Allison; Liu, Yunjie; Haugen, Matz; Tsiang, Michael;

Quantifying the influence of global warming on unprecedented extreme climate events.

Science.gov (United States)

Diffenbaugh, Noah S; Singh, Deepti; Mankin, Justin S; Horton, Daniel E; Swain, Daniel L; Touma, Danielle; Charland, Allison; Liu, Yunjie; Haugen, Matz; Tsiang, Michael; Rajaratnam, Bala

2017-05-09

Efforts to understand the influence of historical global warming on individual extreme climate events have increased over the past decade. However, despite substantial progress, events that are unprecedented in the local observational record remain a persistent challenge. Leveraging observations and a large climate model ensemble, we quantify uncertainty in the influence of global warming on the severity and probability of the historically hottest month, hottest day, driest year, and wettest 5-d period for different areas of the globe. We find that historical warming has increased the severity and probability of the hottest month and hottest day of the year at >80% of the available observational area. Our framework also suggests that the historical climate forcing has increased the probability of the driest year and wettest 5-d period at 57% and 41% of the observed area, respectively, although we note important caveats. For the most protracted hot and dry events, the strongest and most widespread contributions of anthropogenic climate forcing occur in the tropics, including increases in probability of at least a factor of 4 for the hottest month and at least a factor of 2 for the driest year. We also demonstrate the ability of our framework to systematically evaluate the role of dynamic and thermodynamic factors such as atmospheric circulation patterns and atmospheric water vapor, and find extremely high statistical confidence that anthropogenic forcing increased the probability of record-low Arctic sea ice extent.

Modelling Interglacial Climate

DEFF Research Database (Denmark)

Pedersen, Rasmus Anker

the impact of a changing sea ice cover. The first part focusses on the last interglacial climate (125,000 years before present) which was characterized by substantial warming at high northern latitudes due to an increased insolation during summer. The simulations reveal that the oceanic changes dominate......Past warm climate states could potentially provide information on future global warming. The past warming was driven by changed insolation rather than an increased greenhouse effect, and thus the warm climate states are expected to be different. Nonetheless, the response of the climate system......, with maximum warming occurring in winter. The three scenarios all affect the climate beyond the Arctic, especially the mid-latitude circulation which is sensitive to the location of the ice loss. Together, the results presented in this thesis illustrate that the changes in the Arctic sea ice cover...

Warm-cold colonization: response of oaks to uplift of the Himalaya-Hengduan Mountains.

Science.gov (United States)

Meng, Hong-Hu; Su, Tao; Gao, Xiao-Yang; Li, Jie; Jiang, Xiao-Long; Sun, Hang; Zhou, Zhe-Kun

2017-06-01

Clarifying the relationship between distribution patterns of organisms and geological events is critical to understanding the impact of environmental changes on organismal evolution. Quercus sect. Heterobalanus is now distributed across the Himalaya-Hengduan Mountains (HHM) and warm lowland in East China, yet how the distribution patterns of this group changed in response to the HHM uplift remains largely unknown. This study examines the effect of tectonic events in the HHM region on the oaks, providing a biological perspective on the geological history of this region. Fifty-six populations of Quercus sect. Heterobalanus were genotyped using four chloroplast DNA regions and nine nuclear simple sequence repeat loci to assess population structure and diversity, supplemented by molecular dating and ancestral area reconstructions. The underlying demographic dynamics were compared using ecological niche models of the species distributions during the last glacial maximum and the present. These analyses illustrate that Quercus sect. Heterobalanus diversified as the HHM uplifted and climatic cooling during the mid-Miocene, colonizing the cold habitats from warm broadleaf mixed forests. Lineages in cold highlands and warm lowlands have diverged as a consequence of local adaptation to diverging climates since the late Miocene. Our results suggest that continuous uplift of the HHM in the late Miocene to early Pliocene accompanied by simultaneous cooling triggered the differentiation of oaks. The biogeography of Quercus sect. Heterobalanus illuminates the geological events responsible for the modern-day HHM. © 2017 John Wiley & Sons Ltd.

Global Deliberative Democracy and Climate Change: Insights from World Wide Views on Global Warming in Australia

Directory of Open Access Journals (Sweden)

Chris Riedy

2011-12-01

Full Text Available On 26 September 2009, approximately 4,000 citizens in 38 countries participated in World Wide Views on Global Warming (WWViews. WWViews was an ambitious first attempt to convene a deliberative mini-public at a global scale, giving people from around the world an opportunity to deliberate on international climate policy and to make recommendations to the decision-makers meeting at the United Nations Climate Change Conference in Copenhagen (COP-15 in December 2009. In this paper, we examine the role that deliberative mini-publics can play in facilitating the emergence of a global deliberative system for climate change response. We pursue this intent through a reflective evaluation of the Australian component of the World Wide Views on Global Warming project (WWViews. Our evaluation of WWViews is mixed. The Australian event was delivered with integrity and feedback from Australian participants was almost universally positive. Globally, WWViews demonstrated that it is feasible to convene a global mini-public to deliberate on issues of global relevance, such as climate change. On the other hand, the contribution of WWViews towards the emergence of a global deliberative system for climate change response was limited and it achieved little influence on global climate change policy. We identify lessons for future global mini-publics, including the need to prioritise the quality of deliberation and provide flexibility to respond to cultural and political contexts in different parts of the world. Future global mini-publics may be more influential if they seek to represent discourse diversity in addition to demographic profiles, use designs that maximise the potential for transmission from public to empowered space, run over longer time periods to build momentum for change and experiment with ways of bringing global citizens together in a single process instead of discrete national events.

[Evolution of maize climate productivity and its response to climate change in Heilongjiang Province, China.

Science.gov (United States)

Li, Xiu Fen; Zhao, Hui Ying; Zhu, Hai Xia; Wang, Ping; Wang, Qiu Jing; Wang, Ming; Li, Yu Guang

2016-08-01

Under the background of climate change, revealing the change trend and spatial diffe-rence of maize climate productivity in-depth and understanding the regularity of maize climatic resources utilization can provide scientific basis for the macro-decision of agricultural production in Heilongjiang Province. Based on the 1981-2014 meteorological data of 72 weather stations and the corresponding maize yield data in Heilongjiang Province, by the methods of step by step revisal, spatial interpolation and linear trend analysis, this paper studied the photosynthetic productivity (PP), light-temperature productivity (LTP), and climatic productivity (CP) of spring maize, and their temporal and spatial variation characteristics, main influencing factors and light energy utilization efficiency, and evaluated the maize climate productivities under different climate scenarios in the future. The results showed that during the study period, the mean PP, LTP and CP in Heilongjiang Province were 26558, 19953, 18742 kg·hm -2 , respectively. Maize PP, LTP and CP were high in plains and low in mountains, and gradually decreased from southwest to northeast. PP, LTP and CP presented significantly increasing trends, and the increase rates were 378, 723 and 560 kg·hm -2 ·(10 a) -1 , respectively. The increase of radiation and temperature had positive effect on maize production in Heilongjiang Province. The potential productivity of maize presented significant response to climate change. The decrease of solar radiation led to the decline of PP in western Songnen Plain, but the increased temperature compensated the negative effect of solar radiation, so the downward trend of LTP was slowed. The response to climate warming was particularly evident in North and East, and LTP was significantly increased, which was sensitive to the change of precipitation in southwest of Songnen Plain and part of Sanjiang Plain. The average ratio of maize actual yield to its climate productivity was only 24

Climate, lies and propaganda; Climat, mensonges et propagande

Energy Technology Data Exchange (ETDEWEB)

Arezki, A.

2010-07-01

There is today a strong scientific controversy between alarmist climatologists who consider that the human activities are responsible of the global warming, and climate-skeptics for whom the climate change has a natural origin. Without any passion and far away from any lobby, the author proposes a radical analysis of the situation by answering the essential questions: what is the real extent of global warming? Is this warming unprecedented? Should we alarm for? Except human activities, what other serious hypotheses could explain the actual climatic change? Beside the scientific aspects, this book reveals also the real political, economical and media-staged aspects of the global warming debate. (J.S.)

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.

Assessing Forest Carbon Response to Climate Change and Disturbances Using Long-term Hydro-climatic Observations and Simulations

Science.gov (United States)

Trettin, C.; Dai, Z.; Amatya, D. M.

2014-12-01

Long-term climatic and hydrologic observations on the Santee Experimental Forest in the lower coastal plain of South Carolina were used to estimate long-term changes in hydrology and forest carbon dynamics for a pair of first-order watersheds. Over 70 years of climate data indicated that warming in this forest area in the last decades was faster than the global mean; 35+ years of hydrologic records showed that forest ecosystem succession three years following Hurricane Hugo caused a substantial change in the ratio of runoff to precipitation. The change in this relationship between the paired watersheds was attributed to altered evapotranspiration processes caused by greater abundance of pine in the treatment watershed and regeneration of the mixed hardwood-pine forest on the reference watershed. The long-term records and anomalous observations are highly valuable for reliable calibration and validation of hydrological and biogeochemical models capturing the effects of climate variability. We applied the hydrological model MIKESHE that showed that runoff and water table level are sensitive to global warming, and that the sustained warming trends can be expected to decrease stream discharge and lower the mean water table depth. The spatially-explicit biogeochemical model Forest-DNDC, validated using biomass measurements from the watersheds, was used to assess carbon dynamics in response to high resolution hydrologic observation data and simulation results. The simulations showed that the long-term spatiotemporal carbon dynamics, including biomass and fluxes of soil carbon dioxide and methane were highly regulated by disturbance regimes, climatic conditions and water table depth. The utility of linked-modeling framework demonstrated here to assess biogeochemical responses at the watershed scale suggests applications for assessing the consequences of climate change within an urbanizing forested landscape. The approach may also be applicable for validating large

Increased evapotranspiration demand in a Mediterranean climate might cause a decline in fungal yields under global warming.

Science.gov (United States)

Ágreda, Teresa; Águeda, Beatriz; Olano, José M; Vicente-Serrano, Sergio M; Fernández-Toirán, Marina

2015-09-01

Wild fungi play a critical role in forest ecosystems, and its recollection is a relevant economic activity. Understanding fungal response to climate is necessary in order to predict future fungal production in Mediterranean forests under climate change scenarios. We used a 15-year data set to model the relationship between climate and epigeous fungal abundance and productivity, for mycorrhizal and saprotrophic guilds in a Mediterranean pine forest. The obtained models were used to predict fungal productivity for the 2021-2080 period by means of regional climate change models. Simple models based on early spring temperature and summer-autumn rainfall could provide accurate estimates for fungal abundance and productivity. Models including rainfall and climatic water balance showed similar results and explanatory power for the analyzed 15-year period. However, their predictions for the 2021-2080 period diverged. Rainfall-based models predicted a maintenance of fungal yield, whereas water balance-based models predicted a steady decrease of fungal productivity under a global warming scenario. Under Mediterranean conditions fungi responded to weather conditions in two distinct periods: early spring and late summer-autumn, suggesting a bimodal pattern of growth. Saprotrophic and mycorrhizal fungi showed differences in the climatic control. Increased atmospheric evaporative demand due to global warming might lead to a drop in fungal yields during the 21st century. © 2015 John Wiley & Sons Ltd.

Life on a warmer earth: Possible climatic consequences of man-made global warming. Executive report 3

Energy Technology Data Exchange (ETDEWEB)

Flohn, H

1981-01-01

This Executive Report derives from IIASA Research Report RR-80-30, Possible Climatic Consequences of a Man-Made Global Warming, by H. Flohn and published separately. It is based on research undertaken to explore the interaction between energy and climate, including the impact on the global climate of three main energy sources: solar, nuclear, and fossil fuels. Its findings describe the global warming effects caused by carbon dioxide released by burning fossil fuels and by other trace gases released into the atmosphere. The approach is paleoclimatic; it provides insight into what global warming will produce by considering what is known about past periods of the earth's history when the global average surface temperature was higher than it is now. The purpose of this report is to put the research findings into layman's language and add related information to provide a general introduction to the global warming problem. Information is presented under the following chapter titles: the scenario in brief; the climatic system; changes in ice cover; changes in atmosphere and oceans; man's effect on climate; taking the earth's temperature; what a hotter earth might mean; beyond immediate prospects; and, today's mixed signals. (JGB)

Climate model diversity in the Northern Hemisphere Polar vortex response to climate change.

Science.gov (United States)

Simpson, I.; Seager, R.; Hitchcock, P.; Cohen, N.

2017-12-01

Global climate models vary widely in their predictions of the future of the Northern Hemisphere stratospheric polar vortex, with some showing a significant strengthening of the vortex, some showing a significant weakening and others displaying a response that is not outside of the range expected from internal variability alone. This inter-model spread in stratospheric predictions may account for some inter-model spread in tropospheric predictions with important implications for the storm tracks and regional climate change, particularly for the North Atlantic sector. Here, our current state of understanding of this model spread and its tropospheric impacts will be reviewed. Previous studies have proposed relationships between a models polar vortex response to climate change and its present day vortex climatology while others have demonstrated links between a models polar vortex response and changing wave activity coming up from the troposphere below under a warming climate. The extent to which these mechanisms can account for the spread in polar vortex changes exhibited by the Coupled Model Intercomparison Project, phase 5 models will be assessed. In addition, preliminary results from a series of idealized experiments with the Community Atmosphere Model will be presented. In these experiments, nudging of the stratospheric zonal mean state has been imposed to mimic the inter-model spread in the polar vortex response to climate change so that the downward influence of the spread in zonal mean stratospheric responses on the tropospheric circulation can be assessed within one model.

What's in a name? Commonalities and differences in public understanding of "climate change" and "global warming"

OpenAIRE

Whitmarsh, Lorraine E.

2009-01-01

This paper reports on findings from a survey of public understanding of climate change and global warming amongst residents in the south of England. Whereas much previous research has relied on survey checklists to measure public understanding of climate change, this study employed a more qualitative approach to reveal participants' unprompted conceptions of climate change and global warming. Overall, the findings show a tendency for the public to dissociate themselves from the causes, impact...

Building Material Preferences in Warm-Humid and Hot-Dry Climates ...

African Journals Online (AJOL)

dry climates in Ghana. Using a combination of closed and open-ended questionnaires, a total of 1281 participants (473 adults and 808 youth) were recruited in Ghana in a two-month survey in Kumasi and Tamale representing the warm-humid ...

Characterizing changes in soil bacterial community structure in response to short-term warming

Energy Technology Data Exchange (ETDEWEB)

Xiong, Jinbo [State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing China; School of Marine Sciences, Ningbo University, Ningbo China; Sun, Huaibo [State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing China; Peng, Fei [Key Laboratory of Desert and Desertification, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou China; Zhang, Huayong [State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing China; Xue, Xian [Key Laboratory of Desert and Desertification, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou China; Gibbons, Sean M. [Argonne National Laboratory Biosciences Division, Argonne IL USA; Graduate Program in Biophysical Sciences, University of Chicago, Chicago IL USA; Gilbert, Jack A. [Argonne National Laboratory Biosciences Division, Argonne IL USA; Department of Ecology and Evolution, University of Chicago, Chicago IL USA; Chu, Haiyan [State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing China

2014-02-18

High altitude alpine meadows are experiencing considerably greater than average increases in soil surface temperature, potentially as a result of ongoing climate change. The effects of warming on plant productivity and soil edaphic variables have been established previously, but the influence of warming on soil microbial community structure has not been well characterized. Here, the impact of 15 months of soil warming (both + 1 and + 2 degrees C) on bacterial community structure was examined in a field experiment on a Tibetan plateau alpine meadow using bar-coded pyrosequencing. Warming significantly changed (P < 0.05) the structure of the soil bacterial community, but the alpha diversity was not dramatically affected. Changes in the abundance of the Actinobacteria and Alphaproteobacteria were found to contribute the most to differences between ambient (AT) and artificially warmed conditions. A variance partitioning analysis (VPA) showed that warming directly explained 7.15% variation in bacterial community structure, while warming-induced changes in soil edaphic and plant phenotypic properties indirectly accounted for 28.3% and 20.6% of the community variance, respectively. Interestingly, certain taxa showed an inconsistent response to the two warming treatments, for example Deltaproteobacteria showed a decreased relative abundance at + 1 degrees C, but a return to AT control relative abundance at + 2 degrees C. This suggests complex microbial dynamics that could result from conditional dependencies between bacterial taxa.

A meta-analysis of soil exoenzyme responses to simulated climate change

Science.gov (United States)

Gebhardt, M.; Espinosa, N. J.; Blankinship, J. C.; Gallery, R. E.

2017-12-01

Microorganisms produce extracellular enzymes to decompose plant matter and drive biogeochemical transformations in soils. Climate change factors, such as warming and altered precipitation patterns, can impact enzyme activity through both direct and indirect mechanisms. Although many individual studies have examined how soil exoenzyme activities respond to climate change manipulations, there is disagreement surrounding the direction of these responses. We performed a synthesis of published studies to examine the influence of warming and altered precipitation on microbial exoenzyme activity. We found that warming increased enzyme activity with a more pronounced effect for oxidative relative to hydrolytic enzymes. Reduced precipitation consistently decreased exoenzyme activity. These responses, however, varied by season, biome, and enzyme type. The majority of studies fitting our criteria (e.g., experiments lasting a minimum of one growing season, paired treatments and controls) were located in North America and Europe. Inferences from this analysis therefore exclude many important ecosystems such as hyper-arid, wetlands, and artic systems. Carbon degrading enzyme activities were less sensitive to climate change manipulations when compared to phosphorus and nitrogen degrading enzyme activities. Linking enzyme activity to biogeochemical processes requires concomitant measurements of organic and inorganic carbon pools, mineralogy, nutrients, microbial biomass and community structure, and heterotrophic respiration within individual studies. Furthermore, linking these parameters to climate and environmental factors will require a comprehensive and consistent inclusion of biotic and abiotic variables among researchers and experiments. Globally, soils contain the largest carbon pools. Understanding the impacts of large-scale perturbations on soil enzyme activity will help to constrain predictions on the fate of biogeochemical transformations and improve model projections.

Causes of model dry and warm bias over central U.S. and impact on climate projections.

Science.gov (United States)

Lin, Yanluan; Dong, Wenhao; Zhang, Minghua; Xie, Yuanyu; Xue, Wei; Huang, Jianbin; Luo, Yong

2017-10-12

Climate models show a conspicuous summer warm and dry bias over the central United States. Using results from 19 climate models in the Coupled Model Intercomparison Project Phase 5 (CMIP5), we report a persistent dependence of warm bias on dry bias with the precipitation deficit leading the warm bias over this region. The precipitation deficit is associated with the widespread failure of models in capturing strong rainfall events in summer over the central U.S. A robust linear relationship between the projected warming and the present-day warm bias enables us to empirically correct future temperature projections. By the end of the 21st century under the RCP8.5 scenario, the corrections substantially narrow the intermodel spread of the projections and reduce the projected temperature by 2.5 K, resulting mainly from the removal of the warm bias. Instead of a sharp decrease, after this correction the projected precipitation is nearly neutral for all scenarios.Climate models repeatedly show a warm and dry bias over the central United States, but the origin of this bias remains unclear. Here the authors associate this bias to precipitation deficits in models and after applying a correction, projected precipitation in this region shows no significant changes.

The response of soil processes to climate change

DEFF Research Database (Denmark)

Emmett, B.A.; Beier, C.; Estiarte, M.

2004-01-01

Predicted changes in climate may affect key soil processes such as respiration and net nitrogen (N) mineralization and thus key ecosystem functions such as carbon (C) storage and nutrient availability. To identify the sensitivity of shrubland soils to predicted climate changes, we have carried out...... the environmental gradient with the results from the manipulation experiments provides evidence for strong climate controls on soil respiration, net N mineralization and nitrification, and litter decomposition. Trends of 0%-19% increases of soil respiration in response to warming and decreases of 3%-29% in response...... to drought were observed. Across the environmental gradient and below soil temperatures of 20degreesC at a depth of 5-10 cm, a mean Q(10) of 4.1 in respiration rates was observed although this varied from 2.4 to 7.0 between sites. Highest Q(10), values were observed in Spain and the UK and were therefore...

ENSO related decadal scale climate variability from the Indo-Pacific Warm Pool

NARCIS (Netherlands)

Brijker, J.M.; Jung, S.J.A.; Ganssen, G.M.; Bickert, T.; Kroon, D.

2006-01-01

The El Niño-Southern Oscillation (ENSO) is a climatic phenomenon that affects socio-economical welfare in vast areas in the world. A continuous record of Holocene ENSO related climate variability of the Indo-Pacific Warm pool (IPWP) is constructed on the basis of stable oxygen isotopes in shells of

Asymmetric Response of the Equatorial Pacific SST to Climate Warming and Cooling

Energy Technology Data Exchange (ETDEWEB)

Liu, Fukai [Physical Oceanography Laboratory/Qingdao Collaborative Innovation Center of Marine Science and Technology, Ocean University of China, and Qingdao National Laboratory for Marine Science and Technology, Qingdao, China; Luo, Yiyong [Physical Oceanography Laboratory/Qingdao Collaborative Innovation Center of Marine Science and Technology, Ocean University of China, and Qingdao National Laboratory for Marine Science and Technology, Qingdao, China; Lu, Jian [Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland, Washington; Garuba, Oluwayemi [Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland, Washington; Wan, Xiuquan [Physical Oceanography Laboratory/Qingdao Collaborative Innovation Center of Marine Science and Technology, Ocean University of China, and Qingdao National Laboratory for Marine Science and Technology, Qingdao, China

2017-09-01

The response of the equatorial Pacific Ocean to heat fluxes of equal amplitude but opposite sign is investigated using the Community Earth System Model (CESM). Results show a strong asymmetry in SST changes. In the eastern equatorial Pacific (EEP), the warming responding to the positive forcing exceeds the cooling to the negative forcing; while in the western equatorial Pacific (WEP), it is the other way around and the cooling surpasses the warming. This leads to a zonal dipole asymmetric structure, with positive values in the east and negative values in the west. A surface heat budget analysis suggests that the SST asymmetry is mainly resulted from the oceanic horizontal advection and vertical entrainment, with both of their linear and nonlinear components playing a role. For the linear component, its change appears to be more significant over the EEP (WEP) in the positive (negative) forcing scenario, favoring the seesaw pattern of the SST asymmetry. For the nonlinear component, its change acts to warm (cool) the EEP (WEP) in both scenarios, also favorable for the development of the SST asymmetry. Additional experiments with a slab ocean confirm the dominant role of ocean dynamical processes for this SST asymmetry. The net surface heat flux, in contrast, works to reduce the SST asymmetry through its shortwave radiation and latent heat flux components, with the former being related to the nonlinear relationship between SST and convection, and the latter being attributable to Newtonian damping and air-sea stability effects. The suppressing effect of shortwave radiation on SST asymmetry is further verified by partially coupled overriding experiments.

Plant community responses to climate change

Energy Technology Data Exchange (ETDEWEB)

Kongstad, J.

2012-07-01

ecosystem more resilient to the climatic treatments than expected. We also found that the amount of flowering culms of D. flexuosa increased in response to increased CO{sub 2}, whereas the seed germination success decreased. The bryophyte biomass and the nitrogen content decreased in response to nitrogen addition. Even such apparently minor changes might, given time, affect the plant composition and thereby possibly also the major ecosystem processes. Further, we observed changes in the aboveground plant composition in response to the climate manipulations at the Mols site, where C. vulgaris was regenerating after a disturbance. Here a decrease in biomass of the pioneer stage was seen, when subjected to the drought treatment compared to warmed and control treatments. I therefore conclude, that the stage of the C. vulgaris population as well as the magnitude and frequency of disturbances determine the effects of future climate change on the plant community in heathland ecosystems. (Author)

Water runoff vs modern climatic warming in mountainous cryolithic zone in North-East Russia

Science.gov (United States)

Glotov, V. E.; Glotova, L. P.

2018-01-01

The article presents the results of studying the effects of current climatic warming for both surface and subsurface water runoffs in North-East Russia, where the Main Watershed of the Earth separates it into the Arctic and Pacific continental slopes. The process of climatic warming is testified by continuous weather records during 80-100 years and longer periods. Over the Arctic slope and in the northern areas of the Pacific slope, climatic warming results in a decline in a total runoff of rivers whereas the ground-water recharge becomes greater in winter low-level conditions. In the southern Pacific slope and in the Sea of Okhotsk basin, the effect of climatic warming is an overall increase in total runoff including its subsurface constituents. We believe these peculiar characters of river runoff there to be related to the cryolithic zone environments. Over the Arctic slope and the northern Pacific slope, where cryolithic zone is continuous, the total runoff has its subsurface constituent as basically resulting from discharge of ground waters hosted in seasonally thawing rocks. Warmer climatic conditions favor growth of vegetation that needs more water for the processes of evapotranspiration and evaporation from rocky surfaces in summer seasons. In the Sea of Okhotsk basin, where the cryolithic zone is discontinuous, not only ground waters in seasonally thawing layers, but also continuous taliks and subpermafrost waters participate in processes of river recharges. As a result, a greater biological productivity of vegetation cover does not have any effect on ground-water supply and river recharge processes. If a steady climate warming is provided, a continuous cryolithic zone can presumably degrade into a discontinuous and then into an island-type permafrost layer. Under such a scenario, there will be a general increase in the total runoff and its subsurface constituent. From geoecological viewpoints, a greater runoff will have quite positive effects, whereas some

Warming impact on energy use of HVAC system in buildings of different thermal qualities and in different climates

International Nuclear Information System (INIS)

Kharseh, Mohamad; Altorkmany, Lobna; Al-Khawaj, Mohammed; Hassani, Ferri

2014-01-01

Highlights: • Improving TQBE reduces heating load, while it might increase cooling load. • Warming impact on energy use of HVAC varies from one climate to another. • Warming impact on energy use of HVAC depends on building’s thermal quality. • In mild climate, warming does not have a significant impact on energy use of HVAC. - Abstract: In order to combat climate change, energy use in the building must be further reduced. Heating ventilation and air conditioning (HVAC) systems in residential buildings account for considerable fraction of global energy consumption. The potential contribution the domestic sector can make in reducing energy consumption is recognized worldwide. The driving energy of HVACs depends on the thermal quality of the building envelope (TQBE) and outside temperature. Definitely, building regulations are changing with the time toward reduce the thermal loads of buildings. However, most of the existing residential buildings were built to lower TQBE. For instant, 72% of residential dwellings in the 15-EU were built before 1972. To investigate the impact of warming on driving energy of HVACs of a residential building a computer model was developed. Three climate categories/cities were considered, i.e. Stockholm (cold), Istanbul (mild), and Doha (hot). In each city, two buildings were modeled: one was assumed to be built according to the current local buildings regulations (standard TQBE), while the anther was built to lower TQBE. The simulations were run for present and future (in 2050) outdoor designing conditions. The calculations show that the impact of the warming on annual driving energy of HVACs (reduction or increase) depends very much on the climate category and on the TQBE. Based on the climate and TQBE, the change in annual HVACs energy varies from −7.4% (in cold climate) to 12.7% (in hot climate). In mild climate, it was shown that the warming does not have significant impact on annual HVACs energy. Improving the TQBE can

Energy analysis of alternative CO2 refrigeration system configurations for retail food applications in moderate and warm climates

International Nuclear Information System (INIS)

Tsamos, K.M.; Ge, Y.T.; Santosa, IDewa; Tassou, S.A.; Bianchi, G.; Mylona, Z.

2017-01-01

Highlights: • Alternative CO 2 refrigeration technologies are compared for temperate and warm climates. • The CO 2 booster system with parallel compression was found to be the most energy efficient system. • Parallel compression can offer efficiency advantages of 3.6% in moderate and 5.0% in warm climates. • Parallel compression in booster CO 2 systems is economically attractive in warm climates. - Abstract: Refrigeration systems are crucial in retail food stores to ensure appropriate merchandising of food products. This paper compares four different CO 2 refrigeration system configurations in terms of cooling performance, environmental impact, power consumption and annual running costs. The systems studied were the conventional booster refrigeration system with gas bypass (reference system), the all CO 2 cascade system with gas bypass, a booster system with a gas bypass compressor, and integrated cascade all CO 2 system with gas bypass compressor. The weather conditions of London, UK, and Athens, Greece, were used for the modelling of energy consumption and environmental impacts to represent moderate and warm climatic conditions respectively. The control strategies for the refrigeration systems were derived from experimental tests in the laboratory on a conventional booster refrigeration system. The results from the analysis showed that the CO 2 booster system with gas bypass compressor can provide best performance with 5.0% energy savings for the warm climate and 3.65% for the moderate climate, followed by the integrated cascade all CO 2 system with gas bypass compressor, with 3.6% and 2.1% savings over the reference system for the warm and moderate climates respectively.

Global scale climate-crop yield relationships and the impacts of recent warming

International Nuclear Information System (INIS)

Lobell, David B; Field, Christopher B

2007-01-01

Changes in the global production of major crops are important drivers of food prices, food security and land use decisions. Average global yields for these commodities are determined by the performance of crops in millions of fields distributed across a range of management, soil and climate regimes. Despite the complexity of global food supply, here we show that simple measures of growing season temperatures and precipitation-spatial averages based on the locations of each crop-explain ∼30% or more of year-to-year variations in global average yields for the world's six most widely grown crops. For wheat, maize and barley, there is a clearly negative response of global yields to increased temperatures. Based on these sensitivities and observed climate trends, we estimate that warming since 1981 has resulted in annual combined losses of these three crops representing roughly 40 Mt or $5 billion per year, as of 2002. While these impacts are small relative to the technological yield gains over the same period, the results demonstrate already occurring negative impacts of climate trends on crop yields at the global scale

Seed dormancy and germination changes of snowbed species under climate warming: the role of pre- and post-dispersal temperatures

Science.gov (United States)

Bernareggi, Giulietta; Carbognani, Michele; Mondoni, Andrea; Petraglia, Alessandro

2016-01-01

Background and Aims Climate warming has major impacts on seed germination of several alpine species, hence on their regeneration capacity. Most studies have investigated the effects of warming after seed dispersal, and little is known about the effects a warmer parental environment may have on germination and dormancy of the seed progeny. Nevertheless, temperatures during seed development and maturation could alter the state of dormancy, affecting the timing of emergence and seedling survival. Here, the interplay between pre- and post-dispersal temperatures driving seed dormancy release and germination requirements of alpine plants were investigated. Methods Three plant species inhabiting alpine snowbeds were exposed to an artificial warming treatment (i.e. +1·5 K) and to natural conditions in the field. Seeds produced were exposed to six different periods of cold stratification (0, 2, 4, 8, 12 and 20 weeks at 0 °C), followed by four incubation temperatures (5, 10, 15 and 20 °C) for germination testing. Key Results A warmer parental environment produced either no or a significant increase in germination, depending on the duration of cold stratification, incubation temperatures and their interaction. In contrast, the speed of germination was less sensitive to changes in the parental environment. Moreover, the effects of warming appeared to be linked to the level of (physiological) seed dormancy, with deeper dormant species showing major changes in response to incubation temperatures and less dormant species in response to cold stratification periods. Conclusions Plants developed under warmer climates will produce seeds with changed germination responses to temperature and/or cold stratification, but the extent of these changes across species could be driven by seed dormancy traits. Transgenerational plastic adjustments of seed germination and dormancy shown here may result from increased seed viability, reduced primary and secondary dormancy state, or both, and

The response of vegetation structure to active warming and precipitation reduction of the Sphagnum peatland

Science.gov (United States)

Łuców, Dominika; Basińska, Anna; Chojnicki, Bogdan; Gąbka, Maciej; Józefczyk, Damian; Juszczak, Radosław; Leśny, Jacek; Olejnik, Janusz; Reczuga, Monika; Samson, Mateusz; Silvennoinen, Hanna; Stróżecki, Marcin; Urbaniak, Marek; Zielińska, Małgorzata; Lamentowicz, Mariusz

2017-04-01

The recent climate change (e.g. increased temperature and decreased precipitation) is expected to affect biodiversity and vegetation structure of the European peatlands, as well as carbon fluxes. Our experimental study carried out in Western Poland, tests the hypothesis that the increased temperature, in particular in combination with rainfall reduction affects vegetation structure of the Sphagnum peatland, through changes in moss and vascular plants abundance. The innovative climate manipulation system was installed on the Rzecin peatland in 2014. The field site consists of four blocks: "drought" "warming and drought" "warming" and "control". The air and peat temperatures were increased in 2015 and 2016 by about 0.2 oC and 1.0 oC, respectively, using infrared radiators. Precipitation was reduced by automatic curtain operated only during the nights by about 37 % in both years. Data resulting from the analyses of digital pictures as well as Point Intercept method were used to identify changes in vegetation structure as a response to warming and drought. We observed increase in abundance of vascular plant and decrease in abundance of mosses during the very dry 2015 vegetation season. It appeared that Carex spp. (C. limosa and C. rostrata) abundance responded positively to warming, while Sphagnum spp. (S. angustifolium and S. teres) responded negatively. The "warming" block was characterized by an increase in abundance of Carex spp. by 8.3 % to 16.7 % and decreased abundance of Sphagnum spp. from 25 % to 19.4 %, whereas in the block of "warming and drought" 11.4 % to by 18.3 and 38 % to 26.9 %, respectively in the August 2015. However, we observed decrease in Sphagnum spp. abundance in the treatment with rainfall reduction in wetter 2016, and their increase in the control. Our results show how considerable changes in vegetation structure can be expected under the stress of warming and modified rainfall conditions, even after a short-term manipulation. However, it is

Plant movements and climate warming

DEFF Research Database (Denmark)

De Frenne, Pieter; Coomes, David A.; De Schrijver, An

2014-01-01

environments can establish in nonlocal sites. •We assess the intraspecific variation in growth responses to nonlocal soils by planting a widespread grass of deciduous forests (Milium effusum) into an experimental common garden using combinations of seeds and soil sampled in 22 sites across its distributional...... range, and reflecting movement scenarios of up to 1600 km. Furthermore, to determine temperature and forest-structural effects, the plants and soils were experimentally warmed and shaded. •We found significantly positive effects of the difference between the temperature of the sites of seed and soil...... collection on growth and seedling emergence rates. Migrant plants might thus encounter increasingly favourable soil conditions while tracking the isotherms towards currently ‘colder’ soils. These effects persisted under experimental warming. Rising temperatures and light availability generally enhanced plant...

The responses of a forest model to serial correlations of global warming

International Nuclear Information System (INIS)

Cohen, Y.; Pastor, J.

1991-01-01

Predictions of CO 2 -inducing changes to climate have focused on equilibrial responses of the global climate system to different levels of trace-gas forcings. The authors forced a forest ecosystem model with linear changes in temperature and precipitation and varied the degree of serial correlation around mean values. The ecosystem model considers the establishment and growth of individual trees in a 1/12 haplot and their responses to degree days, soil water deficits, soil nitrogen availability, and light. A recent formal analysis indicates that the model output is more sensitive to changes in means and variances of temperature, as opposed to precipitation. Of particular interest to the current paper is the assumption that the probability of mortality increases from about 10% to 30% upon two consecutive years of slow growth due to stress. Thus, year-to-year serial correlations could potentially increase mortality compared with random variation between years. Using this model, Pastor and Post (1988) showed that the forests of the boreal-northern hardwood transition zone in the Lake Superior region are particularly sensitive to climate warming

Rapid climate variability during warm and cold periods in polar regions and Europe

DEFF Research Database (Denmark)

Masson-Delmotte, V.; Landais, A.; Combourieu-Nebout, N.

2005-01-01

Typical rapid climate events punctuating the last glacial period in Greenland, Europe and Antarctica are compared to two rapid events occurring under warmer conditions: (i) Dansgaard-Oeschger event 25, the first abrupt warming occurring during last glacial inception; (ii) 8.2 ka BP event, the only...... rapid cooling recorded during the Holocene in Greenland ice cores and in Ammersee, Germany. The rate of warming during previous warmer interglacial periods is estimated from polar ice cores to 1.5 °C per millennium, without abrupt changes. Climate change expected for the 21st century should however...

A zero-power warming chamber for investigating plant responses to rising temperature

Directory of Open Access Journals (Sweden)

K. F. Lewin

2017-09-01

Full Text Available Advances in understanding and model representation of plant and ecosystem responses to rising temperature have typically required temperature manipulation of research plots, particularly when considering warming scenarios that exceed current climate envelopes. In remote or logistically challenging locations, passive warming using solar radiation is often the only viable approach for temperature manipulation. However, current passive warming approaches are only able to elevate the mean daily air temperature by  ∼  1.5 °C. Motivated by our need to understand temperature acclimation in the Arctic, where warming has been markedly greater than the global average and where future warming is projected to be  ∼  2–3 °C by the middle of the century; we have developed an alternative approach to passive warming. Our zero-power warming (ZPW chamber requires no electrical power for fully autonomous operation. It uses a novel system of internal and external heat exchangers that allow differential actuation of pistons in coupled cylinders to control chamber venting. This enables the ZPW chamber venting to respond to the difference between the external and internal air temperatures, thereby increasing the potential for warming and eliminating the risk of overheating. During the thaw season on the coastal tundra of northern Alaska our ZPW chamber was able to elevate the mean daily air temperature 2.6 °C above ambient, double the warming achieved by an adjacent passively warmed control chamber that lacked our hydraulic system. We describe the construction, evaluation and performance of our ZPW chamber and discuss the impact of potential artefacts associated with the design and its operation on the Arctic tundra. The approach we describe is highly flexible and tunable, enabling customization for use in many different environments where significantly greater temperature manipulation than that possible with existing passive warming

A zero-power warming chamber for investigating plant responses to rising temperature

Science.gov (United States)

Lewin, Keith F.; McMahon, Andrew M.; Ely, Kim S.; Serbin, Shawn P.; Rogers, Alistair

2017-09-01

Advances in understanding and model representation of plant and ecosystem responses to rising temperature have typically required temperature manipulation of research plots, particularly when considering warming scenarios that exceed current climate envelopes. In remote or logistically challenging locations, passive warming using solar radiation is often the only viable approach for temperature manipulation. However, current passive warming approaches are only able to elevate the mean daily air temperature by ˜ 1.5 °C. Motivated by our need to understand temperature acclimation in the Arctic, where warming has been markedly greater than the global average and where future warming is projected to be ˜ 2-3 °C by the middle of the century; we have developed an alternative approach to passive warming. Our zero-power warming (ZPW) chamber requires no electrical power for fully autonomous operation. It uses a novel system of internal and external heat exchangers that allow differential actuation of pistons in coupled cylinders to control chamber venting. This enables the ZPW chamber venting to respond to the difference between the external and internal air temperatures, thereby increasing the potential for warming and eliminating the risk of overheating. During the thaw season on the coastal tundra of northern Alaska our ZPW chamber was able to elevate the mean daily air temperature 2.6 °C above ambient, double the warming achieved by an adjacent passively warmed control chamber that lacked our hydraulic system. We describe the construction, evaluation and performance of our ZPW chamber and discuss the impact of potential artefacts associated with the design and its operation on the Arctic tundra. The approach we describe is highly flexible and tunable, enabling customization for use in many different environments where significantly greater temperature manipulation than that possible with existing passive warming approaches is desired.

GLOBAL WARMING AND CLIMATE CHANGE IN SOUTH AMERICA

Directory of Open Access Journals (Sweden)

PATRICK PATERSON

2017-12-01

Full Text Available Global warming presents one of the most serious threats to South American nations. Countries in the region are at risk of a variety of climate change related problems: rising sea levels, diminishing potable water supplies, forest res, intense storms and ooding, heat waves and the spread of diseases. These disasters are occurring more frequently in the region and will likely increase in intensity also. The armed forces in the region are the only government departments with both the capacity and the manpower to respond to these massive catastrophes. Military support to civilian authorities will be required more frequently and under more severe conditions as climate change conditions worsen.

A matter of degrees: A primer on global warming

International Nuclear Information System (INIS)

1993-01-01

A primer on global warming is presented in order to provide information to Canadians on making environmentally responsible decisions. The fundamentals of natural climate change, the atmospheric environment, factors that influence climate, and the greenhouse effect are explained. Global warming is then discussed with reference to paleoclimatic research, the influence of human activity on increased concentrations of greenhouse gases, and predictions of future climates. The possible impacts of global warming on Canada are described for such sectors as forests, fisheries, agriculture, sea levels, health, energy supply and demand, and the Arctic regions. The actions that citizens and governments can take in order to mitigate or adapt to global warming are then presented. A glossary and index are included. 55 refs., 17 figs

Reduced interdecadal variability of Atlantic Meridional Overturning Circulation under global warming.

Science.gov (United States)

Cheng, Jun; Liu, Zhengyu; Zhang, Shaoqing; Liu, Wei; Dong, Lina; Liu, Peng; Li, Hongli

2016-03-22

Interdecadal variability of the Atlantic Meridional Overturning Circulation (AMOC-IV) plays an important role in climate variation and has significant societal impacts. Past climate reconstruction indicates that AMOC-IV has likely undergone significant changes. Despite some previous studies, responses of AMOC-IV to global warming remain unclear, in particular regarding its amplitude and time scale. In this study, we analyze the responses of AMOC-IV under various scenarios of future global warming in multiple models and find that AMOC-IV becomes weaker and shorter with enhanced global warming. From the present climate condition to the strongest future warming scenario, on average, the major period of AMOC-IV is shortened from ∼50 y to ∼20 y, and the amplitude is reduced by ∼60%. These reductions in period and amplitude of AMOC-IV are suggested to be associated with increased oceanic stratification under global warming and, in turn, the speedup of oceanic baroclinic Rossby waves.

Reduced interdecadal variability of Atlantic Meridional Overturning Circulation under global warming

Science.gov (United States)

Cheng, Jun; Liu, Zhengyu; Zhang, Shaoqing; Liu, Wei; Dong, Lina; Liu, Peng; Li, Hongli

2016-01-01

Interdecadal variability of the Atlantic Meridional Overturning Circulation (AMOC-IV) plays an important role in climate variation and has significant societal impacts. Past climate reconstruction indicates that AMOC-IV has likely undergone significant changes. Despite some previous studies, responses of AMOC-IV to global warming remain unclear, in particular regarding its amplitude and time scale. In this study, we analyze the responses of AMOC-IV under various scenarios of future global warming in multiple models and find that AMOC-IV becomes weaker and shorter with enhanced global warming. From the present climate condition to the strongest future warming scenario, on average, the major period of AMOC-IV is shortened from ∼50 y to ∼20 y, and the amplitude is reduced by ∼60%. These reductions in period and amplitude of AMOC-IV are suggested to be associated with increased oceanic stratification under global warming and, in turn, the speedup of oceanic baroclinic Rossby waves. PMID:26951654

Vegetation exerts a greater control on litter decomposition than climate warming in peatlands.

Science.gov (United States)

Ward, Susan E; Orwin, Kate H; Ostle, Nicholas J; Briones, J I; Thomson, Bruce C; Griffiths, Robert I; Oakley, Simon; Quirk, Helen; Bardget, Richard D

2015-01-01

Historically, slow decomposition rates have resulted in the accumulation of large amounts of carbon in northern peatlands. Both climate warming and vegetation change can alter rates of decomposition, and hence affect rates of atmospheric CO2 exchange, with consequences for climate change feedbacks. Although warming and vegetation change are happening concurrently, little is known about their relative and interactive effects on decomposition processes. To test the effects of warming and vegetation change on decomposition rates, we placed litter of three dominant species (Calluna vulgaris, Eriophorum vaginatum, Hypnum jutlandicum) into a peatland field experiment that combined warming.with plant functional group removals, and measured mass loss over two years. To identify potential mechanisms behind effects, we also measured nutrient cycling and soil biota. We found that plant functional group removals exerted a stronger control over short-term litter decomposition than did approximately 1 degrees C warming, and that the plant removal effect depended on litter species identity. Specifically, rates of litter decomposition were faster when shrubs were removed from the plant community, and these effects were strongest for graminoid and bryophyte litter. Plant functional group removals also had strong effects on soil biota and nutrient cycling associated with decomposition, whereby shrub removal had cascading effects on soil fungal community composition, increased enchytraeid abundance, and increased rates of N mineralization. Our findings demonstrate that, in addition to litter quality, changes in vegetation composition play a significant role in regulating short-term litter decomposition and belowground communities in peatland, and that these impacts can be greater than moderate warming effects. Our findings, albeit from a relatively short-term study, highlight the need to consider both vegetation change and its impacts below ground alongside climatic effects when

Negative impacts of high temperatures on growth of black spruce forests intensify with the anticipated climate warming.

Science.gov (United States)

Girardin, Martin P; Hogg, Edward H; Bernier, Pierre Y; Kurz, Werner A; Guo, Xiao Jing; Cyr, Guillaume

2016-02-01

An increasing number of studies conclude that water limitations and heat stress may hinder the capacity of black spruce (Picea mariana (Mill.) B.S.P.) trees, a dominant species of Canada's boreal forests, to grow and assimilate atmospheric carbon. However, there is currently no scientific consensus on the future of these forests over the next century in the context of widespread climate warming. The large spatial extent of black spruce forests across the Canadian boreal forest and associated variability in climate, demography, and site conditions pose challenges for projecting future climate change responses. Here we provide an evaluation of the impacts of climate warming and drying, as well as increasing [CO2 ], on the aboveground productivity of black spruce forests across Canada south of 60°N for the period 1971 to 2100. We use a new extensive network of tree-ring data obtained from Canada's National Forest Inventory, spatially explicit simulations of net primary productivity (NPP) and its drivers, and multivariate statistical modeling. We found that soil water availability is a significant driver of black spruce interannual variability in productivity across broad areas of the western to eastern Canadian boreal forest. Interannual variability in productivity was also found to be driven by autotrophic respiration in the warmest regions. In most regions, the impacts of soil water availability and respiration on interannual variability in productivity occurred during the phase of carbohydrate accumulation the year preceding tree-ring formation. Results from projections suggest an increase in the importance of soil water availability and respiration as limiting factors on NPP over the next century due to warming, but this response may vary to the extent that other factors such as carbon dioxide fertilization, and respiration acclimation to high temperature, contribute to dampening these limitations. © 2015 Her Majesty the Queen in Right of Canada. Reproduced with

Enhanced greenhouse warming: Regional response and believability

International Nuclear Information System (INIS)

Etkin, D.

1991-01-01

Climate models predict significant changes in the world's climate over the next 50-100 y due to increasing atmospheric greenhouse gases. To what extent these predictions can be believed has been the subject of considerable scientific debate. The ability of climate models to reproduce the current climate depends on how well the available data sets specify the earth's climate and how well the models reproduce that specification. A study of historical and paleo climates provides information on how the climate system operates and on past fluctuations in climate, and may also provide useful analogues of future climates. The best tools for understanding and predicting future climate changes are likely numerical models. Sophisticated climate models suffer from uncertainties about the feedback loops present in the real climate system. The ability of global circulation models to replicate current climate globally is fairly good, but significant disagreements have been found among different models at regional scales. For a region such as the Mackenzie Valley, understanding of historical and current climate is essential in terms of developing reasonable scenarios of future climate change. Uncertainty will probably remain an issue with respect to greenhouse warming for the foreseeable future, and as a result the detailed climate prediction on a regional scale needed for some kinds of impact studies may not be attainable. 73 refs., 9 figs., 1 tab

Anthropogenic flank attack on polar bears: Interacting consequences of climate warming and pollutant exposure

Directory of Open Access Journals (Sweden)

Bjørn Munro Jenssen

2015-02-01

Full Text Available Polar bears (Ursus maritimus are subjected to several anthropogenic threats, climate warming and exposure to pollutants being two of these. For polar bears, one of the main effects of climate warming is limited access to prey, due to loss of their sea ice habitat. This will result in prolonged fasting periods and emaciation and condition related negative effects on survival and reproduction success. Prolonged fasting will result in increases of the tissue concentrations of persistent organic pollutants (POPs in polar bears, and thus increase the probability for POP levels to exceed threshold levels for effects on health, and thus on reproductive success and survival. There are clear potentials for interactions between impacts of climate warming and impacts of pollutant exposure on polar bears. It is likely that that fasting-induced increases of POPs will add to mortality rates and decrease reproductive success beyond effects caused by loss of habitat alone. However, there is a lack of studies that have addressed this. Thus, there is a need to focus on population effects of POP exposure in polar bears, and to consider such effects in relation to the effects of climate induced habitat loss.

Multisectoral Climate Impact Hotspots in a Warming World

Science.gov (United States)

Piontek, Franziska; Mueller, Christoph; Pugh, Thomas A. M.; Clark, Douglas B.; Deryng, Delphine; Elliott, Joshua; deJesusColonGonzalez, Felipe; Floerke, Martina; Folberth, Christian; Franssen, Wietse;

California golden trout and climate change: Is their stream habitat vulnerable to climate warming?

Science.gov (United States)

Kathleen R. Matthews

2010-01-01

The California golden trout (CGT) Oncorhynchus mykiss aguabonita is one of the few native high-elevation fish in the Sierra Nevada. They are already in trouble because of exotic trout, genetic introgression, and degraded habitat, and now face further stress from climate warming. Their native habitat on the Kern Plateau meadows mostly in the Golden...

Responses to Projected Changes in Climate and UV-B at the Species Level

Energy Technology Data Exchange (ETDEWEB)

Callaghan, Terry V. [Abisko Scientific Research Station, Abisko (Sweden); Bjoern, Lars Olof [Lund Univ. (Sweden). Dept. of Cell and Organism Biology; Cernov, Yuri [Russian Academy of Sciences, Moscow (Russian Federation). A.N. Severtsov Inst. of Evolutionary Morphology and Animal Ecology] (and others)

2004-11-01

Environmental manipulation experiments showed that species respond individualistically to each environmental-change variable. The greatest responses of plants were generally to nutrient, particularly nitrogen, addition. Summer warming experiments showed that woody plant responses were dominant and that mosses and lichens became less abundant. Responses to warming were controlled by moisture availability and snow cover. Many invertebrates increased population growth in response to summer warming, as long as desiccation was not induced. CO{sub 2} and UV-B enrichment experiments showed that plant and animal responses were small. However, some microorganisms and species of fungi were sensitive to increased UV-B and some intensive mutagenic actions could, perhaps, lead to unexpected epidemic outbreaks. Tundra soil heating, CO{sub 2} enrichment and amendment with mineral nutrients generally accelerated microbial activity. Algae are likely to dominate cyanobacteria in milder climates. Expected increases in winter freeze-thaw cycles leading to ice-crust formation are likely to severely reduce winter survival rate and disrupt the population dynamics of many terrestrial animals. A deeper snow cover is likely to restrict access to winter pastures by reindeer/caribou and their ability to flee from predators while any earlier onset of the snow-free period is likely to stimulate increased plant growth. Initial species responses to climate change might occur at the sub-species level: an Arctic plant or animal species with high genetic/racial diversity has proved an ability to adapt to different environmental conditions in the past and is likely to do so also in the future. Indigenous knowledge, air photographs, satellite images and monitoring show that changes in the distributions of some species are already occurring: Arctic vegetation is becoming more shrubby and more productive, there have been recent changes in the ranges of caribou, and 'new' species of insects and

Heat-Related Mortality in a Warming Climate: Projections for 12 U.S. Cities

Directory of Open Access Journals (Sweden)

Elisaveta P. Petkova

2014-10-01

Full Text Available Heat is among the deadliest weather-related phenomena in the United States, and the number of heat-related deaths may increase under a changing climate, particularly in urban areas. Regional adaptation planning is unfortunately often limited by the lack of quantitative information on potential future health responses. This study presents an assessment of the future impacts of climate change on heat-related mortality in 12 cities using 16 global climate models, driven by two scenarios of greenhouse gas emissions. Although the magnitude of the projected heat effects was found to differ across time, cities, climate models and greenhouse pollution emissions scenarios, climate change was projected to result in increases in heat-related fatalities over time throughout the 21st century in all of the 12 cities included in this study. The increase was more substantial under the high emission pathway, highlighting the potential benefits to public health of reducing greenhouse gas emissions. Nearly 200,000 heat-related deaths are projected to occur in the 12 cities by the end of the century due to climate warming, over 22,000 of which could be avoided if we follow a low GHG emission pathway. The presented estimates can be of value to local decision makers and stakeholders interested in developing strategies to reduce these impacts and building climate change resilience.

Heat-Related Mortality in a Warming Climate: Projections for 12 U.S. Cities

Science.gov (United States)

Petkova, Elisaveta P.; Bader, Daniel A.; Anderson, G. Brooke; Horton, Radley M.; Knowlton, Kim; Kinney, Patrick L.

2014-01-01

Heat is among the deadliest weather-related phenomena in the United States, and the number of heat-related deaths may increase under a changing climate, particularly in urban areas. Regional adaptation planning is unfortunately often limited by the lack of quantitative information on potential future health responses. This study presents an assessment of the future impacts of climate change on heat-related mortality in 12 cities using 16 global climate models, driven by two scenarios of greenhouse gas emissions. Although the magnitude of the projected heat effects was found to differ across time, cities, climate models and greenhouse pollution emissions scenarios, climate change was projected to result in increases in heat-related fatalities over time throughout the 21st century in all of the 12 cities included in this study. The increase was more substantial under the high emission pathway, highlighting the potential benefits to public health of reducing greenhouse gas emissions. Nearly 200,000 heat-related deaths are projected to occur in the 12 cities by the end of the century due to climate warming, over 22,000 of which could be avoided if we follow a low GHG emission pathway. The presented estimates can be of value to local decision makers and stakeholders interested in developing strategies to reduce these impacts and building climate change resilience.

Experimental climate warming decreases photosynthetic efficiency of lichens in an arid South African ecosystem.

Science.gov (United States)

Maphangwa, Khumbudzo Walter; Musil, Charles F; Raitt, Lincoln; Zedda, Luciana

2012-05-01

Elevated temperatures and diminished precipitation amounts accompanying climate warming in arid ecosystems are expected to have adverse effects on the photosynthesis of lichen species sensitive to elevated temperature and/or water limitation. This premise was tested by artificially elevating temperatures (increase 2.1-3.8°C) and reducing the amounts of fog and dew precipitation (decrease 30.1-31.9%), in an approximation of future climate warming scenarios, using transparent hexagonal open-top warming chambers placed around natural populations of four lichen species (Xanthoparmelia austroafricana, X. hyporhytida , Xanthoparmelia. sp., Xanthomaculina hottentotta) at a dry inland site and two lichen species (Teloschistes capensis and Ramalina sp.) at a humid coastal site in the arid South African Succulent Karoo Biome. Effective photosynthetic quantum yields ([Formula: see text]) were measured hourly throughout the day at monthly intervals in pre-hydrated lichens present in the open-top warming chambers and in controls which comprised demarcated plots of equivalent open-top warming chamber dimensions constructed from 5-cm-diameter mesh steel fencing. The cumulative effects of the elevated temperatures and diminished precipitation amounts in the open-top warming chambers resulted in significant decreases in lichen [Formula: see text]. The decreases were more pronounced in lichens from the dry inland site (decline 34.1-46.1%) than in those from the humid coastal site (decline 11.3-13.7%), most frequent and prominent in lichens at both sites during the dry summer season, and generally of greatest magnitude at or after the solar noon in all seasons. Based on these results, we conclude that climate warming interacting with reduced precipitation will negatively affect carbon balances in endemic lichens by increasing desiccation damage and reducing photosynthetic activity time, leading to increased incidences of mortality.

Early onset of industrial-era warming across the oceans and continents.

Science.gov (United States)

Abram, Nerilie J; McGregor, Helen V; Tierney, Jessica E; Evans, Michael N; McKay, Nicholas P; Kaufman, Darrell S

2016-08-25

The evolution of industrial-era warming across the continents and oceans provides a context for future climate change and is important for determining climate sensitivity and the processes that control regional warming. Here we use post-ad 1500 palaeoclimate records to show that sustained industrial-era warming of the tropical oceans first developed during the mid-nineteenth century and was nearly synchronous with Northern Hemisphere continental warming. The early onset of sustained, significant warming in palaeoclimate records and model simulations suggests that greenhouse forcing of industrial-era warming commenced as early as the mid-nineteenth century and included an enhanced equatorial ocean response mechanism. The development of Southern Hemisphere warming is delayed in reconstructions, but this apparent delay is not reproduced in climate simulations. Our findings imply that instrumental records are too short to comprehensively assess anthropogenic climate change and that, in some regions, about 180 years of industrial-era warming has already caused surface temperatures to emerge above pre-industrial values, even when taking natural variability into account.

Using eddy geopotential height to measure the western North Pacific subtropical high in a warming climate

Science.gov (United States)

He, Chao; Lin, Ailan; Gu, Dejun; Li, Chunhui; Zheng, Bin; Wu, Bo; Zhou, Tianjun

2018-01-01

The western North Pacific subtropical high (WNPSH) is crucial to the East Asian summer climate, and geopotential height ( H) is widely used to measure the WPNSH. However, a rapidly rising trend of H in the future is projected by the models from the Coupled Model Intercomparison Project Phase 5 (CMIP5). Diagnoses based on the hypsometric equation suggest that more than 80% of the rise in H are attributable to zonal uniform warming. Because circulation is determined by the gradient of H rather than its absolute magnitude, the spatially uniform rising trend of H gives rise to difficulties when measuring the WNPSH with H. These difficulties include an invalid western boundary of WNPSH in the future and spurious information regarding long-term trends and interannual variability of WNPSH. Using CMIP5 model simulations and reanalysis data, the applicability of a metric based on eddy geopotential height ( H e ) to the warming climate is investigated. The results show that the H e metric outperforms the H metric under warming climate conditions. First, the mean state rainfall- H e relationship is more robust than the rainfall- H relationship. Second, the area, intensity, and western boundary indices of WNPSH can be effectively defined by the H e = 0-m contour in future warming climate scenarios without spurious trends. Third, the interannual variability of East Asian summer rainfall is more closely related to the H e -based WNPSH indices. We recommend that the H e metric be adopted as an operational metric on the WNPSH under the current warming climate.

Progress report for project modeling Arctic barrier island-lagoon system response to projected Arctic warming

Science.gov (United States)

Erikson, Li H.; Gibbs, Ann E.; Richmond, Bruce M.; Storlazzi, Curt; B.M. Jones,

2012-01-01

Changes in Arctic coastal ecosystems in response to global warming may be some of the most severe on the planet. A better understanding and analysis of the rates at which these changes are expected to occur over the coming decades is crucial in order to delineate high-priority areas that are likely to be affected by climate changes. In this study we investigate the likelihood of changes to habitat-supporting barrier island – lagoon systems in response to projected changes in atmospheric and oceanographic forcing associated with Arctic warming. To better understand the relative importance of processes responsible for the current and future coastal landscape, key parameters related to increasing arctic temperatures are investigated and used to establish boundary conditions for models that simulate barrier island migration and inundation of deltaic deposits and low-lying tundra. The modeling effort investigates the dominance and relative importance of physical processes shaping the modern Arctic coastline as well as decadal responses due to projected conditions out to the year 2100.

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)

A sensitivity study to global desertification in cold and warm climates: results from the IPSL OAGCM model

Energy Technology Data Exchange (ETDEWEB)

Alkama, Ramdane [GAME/CNRM, CNRS/Meteo-France, Toulouse (France); Kageyama, Masa; Ramstein, Gilles [LSCE/IPSL UMR CEA-CNRS-UVSQ 8212, Gif sur Yvette (France)

2012-04-15

Many simulations have been devoted to study the impact of global desertification on climate, but very few have quantified this impact in very different climate contexts. Here, the climatic impacts of large-scale global desertification in warm (2100 under the SRES A2 scenario forcing), modern and cold (Last Glacial Maximum, 21 thousand years ago) climates are assessed by using the IPSL OAGCM. For each climate, two simulations have been performed, one in which the continents are covered by modern vegetation, the other in which global vegetation is changed to desert i.e. bare soil. The comparison between desert and present vegetation worlds reveals that the prevailing signal in terms of surface energy budget is dominated by the reduction of upward latent heat transfer. Replacing the vegetation by bare soil has similar impacts on surface air temperature South of 20 N in all three climatic contexts, with a warming over tropical forests and a slight cooling over semi-arid and arid areas, and these temperature changes are of the same order of magnitude. North of 20 N, the difference between the temperatures simulated with present day vegetation and in a desert world is mainly due to the change in net radiation related to the modulation of the snow albedo by vegetation, which is obviously absent in the desert world simulations. The enhanced albedo in the desert world simulations induces a large temperature decrease, especially during summer in the cold and modern climatic contexts, whereas the largest difference occurs during winter in the warm climate. This temperature difference requires a larger heat transport to the northern high latitudes. Part of this heat transport increase is achieved through an intensification of the Atlantic Meridional Overturning Circulation. This intensification reduces the sea-ice extent and causes a warming over the North Atlantic and Arctic oceans in the warm climate context. In contrast, the large cooling North of 20 N in both the modern

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...

Daytime warming has stronger negative effects on soil nematodes than night-time warming

Science.gov (United States)

Yan, Xiumin; Wang, Kehong; Song, Lihong; Wang, Xuefeng; Wu, Donghui

2017-03-01

Warming of the climate system is unequivocal, that is, stronger warming during night-time than during daytime. Here we focus on how soil nematodes respond to the current asymmetric warming. A field infrared heating experiment was performed in the western of the Songnen Plain, Northeast China. Three warming modes, i.e. daytime warming, night-time warming and diurnal warming, were taken to perform the asymmetric warming condition. Our results showed that the daytime and diurnal warming treatment significantly decreased soil nematodes density, and night-time warming treatment marginally affected the density. The response of bacterivorous nematode and fungivorous nematode to experimental warming showed the same trend with the total density. Redundancy analysis revealed an opposite effect of soil moisture and soil temperature, and the most important of soil moisture and temperature in night-time among the measured environment factors, affecting soil nematode community. Our findings suggested that daily minimum temperature and warming induced drying are most important factors affecting soil nematode community under the current global asymmetric warming.

Impacts of climate change on European hydrology at 1.5, 2 and 3 degrees mean global warming above preindustrial level

NARCIS (Netherlands)

Donnelly, Chantal; Greuell, Wouter; Andersson, Jafet; Gerten, Dieter; Pisacane, Giovanna; Roudier, Philippe; Ludwig, Fulco

2017-01-01

Impacts of climate change at 1.5, 2 and 3 °C mean global warming above preindustrial level are investigated and compared for runoff, discharge and snowpack in Europe. Ensembles of climate projections representing each of the warming levels were assembled to describe the hydro-meteorological climate

Mitigation of global warming through renewable biomass

International Nuclear Information System (INIS)

Dhillon, R.S.; Wuehlisch, George von

2013-01-01

Rising level of atmospheric CO 2 and consequent global warming is evident. Global surface temperature have already increased by 0.8 °C over the 20th century and is projected to increase by 1.4–5.8 °C during the twenty-first century. The global warming will continue till atmospheric concentrations of the major greenhouse gases are stabilized. Among them, CO 2 is mainly responsible and is expected to account for about 60% of the warming over the next century. This study reviews advances on causes and consequences of global climate change and its impact on nature and society. Renewable biomass has tremendous potential to mitigate the global warming. Renewable biomass is expected to play a multifunctional role including food production, source of energy and fodder, biodiversity conservation, yield of goods and services to the society as well as mitigation of the impact of climate change. The review highlights the different management and research strategies in forestry, agriculture, agroforestry and grasslands to mitigate the global warming. -- Highlights: ► Rising level of atmospheric CO 2 and consequent global warming is evident. ► CO 2 is mainly responsible for global warming. ► Global temperature is predicted to increase by 1.4–5.8 °C during 21st century. ► Renewable biomass has great potential to mitigate the global warming

Circumpolar dynamics of a marine top-predator track ocean warming rates.

Science.gov (United States)

Descamps, Sébastien; Anker-Nilssen, Tycho; Barrett, Robert T; Irons, David B; Merkel, Flemming; Robertson, Gregory J; Yoccoz, Nigel G; Mallory, Mark L; Montevecchi, William A; Boertmann, David; Artukhin, Yuri; Christensen-Dalsgaard, Signe; Erikstad, Kjell-Einar; Gilchrist, H Grant; Labansen, Aili L; Lorentsen, Svein-Håkon; Mosbech, Anders; Olsen, Bergur; Petersen, Aevar; Rail, Jean-Francois; Renner, Heather M; Strøm, Hallvard; Systad, Geir H; Wilhelm, Sabina I; Zelenskaya, Larisa

2017-09-01

Global warming is a nonlinear process, and temperature may increase in a stepwise manner. Periods of abrupt warming can trigger persistent changes in the state of ecosystems, also called regime shifts. The responses of organisms to abrupt warming and associated regime shifts can be unlike responses to periods of slow or moderate change. Understanding of nonlinearity in the biological responses to climate warming is needed to assess the consequences of ongoing climate change. Here, we demonstrate that the population dynamics of a long-lived, wide-ranging marine predator are associated with changes in the rate of ocean warming. Data from 556 colonies of black-legged kittiwakes Rissa tridactyla distributed throughout its breeding range revealed that an abrupt warming of sea-surface temperature in the 1990s coincided with steep kittiwake population decline. Periods of moderate warming in sea temperatures did not seem to affect kittiwake dynamics. The rapid warming observed in the 1990s may have driven large-scale, circumpolar marine ecosystem shifts that strongly affected kittiwakes through bottom-up effects. Our study sheds light on the nonlinear response of a circumpolar seabird to large-scale changes in oceanographic conditions and indicates that marine top predators may be more sensitive to the rate of ocean warming rather than to warming itself. © 2017 John Wiley & Sons Ltd.

Who decides who has won the bet? Total and Anthropogenic Warming Indices

Science.gov (United States)

Haustein, K.; Allen, M. R.; Otto, F. E. L.; Schmidt, A.; Frame, D. J.; Forster, P.; Matthews, D.

2016-12-01

An extension of the idea of betting markets as a means of revealing opinions about future climate are climate policies indexed to geophysical indicators: for example, to ensure net zero global carbon dioxide emissions by the time anthropogenic warming reaches 1.5 degrees above pre-industrial, given about 1 degree of warming already, emissions must fall, on average, by 20% of their current value for every tenth of a degree of anthropogenic warming from now on. In principle, policies conditioned on some measure of attributable warming are robust to uncertainty in the global climate response: the risk of a higher or lower response than expected is borne by those affected by climate change mitigation policy rather than those affected by climate change impacts, as is the case with emission targets for specific years based on "current understanding" of the response. To implement any indexed policy, or to agree payout terms for any bet on future climate, requires consensus on the definition of the index: how is it calculated, and who is responsible for releasing it? The global mean surface temperature of the current decade relative to pre-industrial may vary by 0.1 degree or more depending on precisely what is measured, what is defined as pre-industrial, and the treatment of regions with sparse data coverage in earlier years. Indices defined using different conventions, however, are all expected to evolve very similarly over the coming decades, so agreeing on a conservative, traceable index such as HadCRUT is more important than debating the "true" global temperature. A more important question is whether indexed policies and betting markets should focus on total warming, including natural and anthropogenic drivers and internal variability, or an Anthropogenic Warming Index (AWI) representing an unbiased estimate of warming attributable to human influence to date. We propose a simple AWI based solely on observed temperatures and global natural and anthropogenic forcing

Midlatitude atmospheric circulation responses under 1.5 and 2.0 °C warming and implications for regional impacts

Directory of Open Access Journals (Sweden)

C. Li

2018-04-01

Full Text Available This study investigates the global response of the midlatitude atmospheric circulation to 1.5 and 2.0 °C of warming using the HAPPI (Half a degree Additional warming, Prognosis and Projected Impacts ensemble, with a focus on the winter season. Characterising and understanding this response is critical for accurately assessing the near-term regional impacts of climate change and the benefits of limiting warming to 1.5 °C above pre-industrial levels, as advocated by the Paris Agreement of the United Nations Framework Convention on Climate Change (UNFCCC. The HAPPI experimental design allows an assessment of uncertainty in the circulation response due to model dependence and internal variability. Internal variability is found to dominate the multi-model mean response of the jet streams, storm tracks, and stationary waves across most of the midlatitudes; larger signals in these features are mostly consistent with those seen in more strongly forced warming scenarios. Signals that emerge in the 1.5 °C experiment are a weakening of storm activity over North America, an inland shift of the North American stationary ridge, an equatorward shift of the North Pacific jet exit, and an equatorward intensification of the South Pacific jet. Signals that emerge under an additional 0.5 °C of warming include a poleward shift of the North Atlantic jet exit, an eastward extension of the North Atlantic storm track, and an intensification on the flanks of the Southern Hemisphere storm track. Case studies explore the implications of these circulation responses for precipitation impacts in the Mediterranean, in western Europe, and on the North American west coast, paying particular attention to possible outcomes at the tails of the response distributions. For example, the projected weakening of the Mediterranean storm track emerges in the 2 °C warmer world, with exceptionally dry decades becoming 5 times more likely.

Climate-induced warming imposes a threat to north European spring ecosystems.

Science.gov (United States)

Jyväsjärvi, Jussi; Marttila, Hannu; Rossi, Pekka M; Ala-Aho, Pertti; Olofsson, Bo; Nisell, Jakob; Backman, Birgitta; Ilmonen, Jari; Virtanen, Risto; Paasivirta, Lauri; Britschgi, Ritva; Kløve, Bjørn; Muotka, Timo

2015-12-01

Interest in climate change effects on groundwater has increased dramatically during the last decade. The mechanisms of climate-related groundwater depletion have been thoroughly reviewed, but the influence of global warming on groundwater-dependent ecosystems (GDEs) remains poorly known. Here we report long-term water temperature trends in 66 northern European cold-water springs. A vast majority of the springs (82%) exhibited a significant increase in water temperature during 1968-2012. Mean spring water temperatures were closely related to regional air temperature and global radiative forcing of the corresponding year. Based on three alternative climate scenarios representing low (RCP2.6), intermediate (RCP6) and high-emission scenarios (RCP8.5), we estimate that increase in mean spring water temperature in the region is likely to range from 0.67 °C (RCP2.6) to 5.94 °C (RCP8.5) by 2086. According to the worst-case scenario, water temperature of these originally cold-water ecosystems (regional mean in the late 1970s: 4.7 °C) may exceed 12 °C by the end of this century. We used bryophyte and macroinvertebrate species data from Finnish springs and spring-fed streams to assess ecological impacts of the predicted warming. An increase in spring water temperature by several degrees will likely have substantial biodiversity impacts, causing regional extinction of native, cold-stenothermal spring specialists, whereas species diversity of headwater generalists is likely to increase. Even a slight (by 1 °C) increase in water temperature may eliminate endemic spring species, thus altering bryophyte and macroinvertebrate assemblages of spring-fed streams. Climate change-induced warming of northern regions may thus alter species composition of the spring biota and cause regional homogenization of biodiversity in headwater ecosystems. © 2015 John Wiley & Sons Ltd.

Persistent cold air outbreaks over North America in a warming climate

International Nuclear Information System (INIS)

Gao, Yang; Leung, L Ruby; Lu, Jian; Masato, Giacomo

2015-01-01

This study examines future changes of cold air outbreaks (CAOs) using a multi-model ensemble of global climate simulations from the Coupled Model Intercomparison Project Phase 5 and high resolution regional climate simulations. Overall, climate models agree on a dip in CAO duration across North America, but the percentage change is consistently smaller from western Canada to the upper mid-western US with historically more frequent CAO. By decomposing the changes of the probability density function of daily surface temperature into changes due to mean warming and changes in standard deviation (std) and skewness/higher order moments, the contributions of each factor to CAO changes are quantified. Results show that CAO changes can be explained largely by the mean warming, but the decrease in temperature std contributes to about 20% reduction of CAO from Alaska to northeastern US and eastern Canada possibly due to the Arctic amplification and weakening of storm track. A thermodynamical modulation of the skewness called the ‘0 °C mode’ effect is found to operate prominently along the 0 °C isotherm hemispherically and reduce CAO in western and northeastern US with winter snow cover by up to 10%. This effect also produces a manifold increase in CAO events over the Arctic sea ice. An increased frequency in atmospheric blocking also contributes to increases in CAO duration over Alaska and the Arctic region. Regional simulations revealed more contributions of existing snowpack to CAO in the near future over the Rocky Mountain, southwestern US, and Great Lakes areas through surface albedo effects. Overall, the multi-model projections emphasize that cold extremes do not completely disappear in a warming climate. Concomitant with the relatively smaller reduction in CAO events in northwestern US, the top five most extreme CAO events may still occur, and wind chill will continue to have societal impacts in that region. (letter)

The ice-core record - Climate sensitivity and future greenhouse warming

Science.gov (United States)

Lorius, C.; Raynaud, D.; Jouzel, J.; Hansen, J.; Le Treut, H.

1990-01-01

The prediction of future greenhouse-gas-warming depends critically on the sensitivity of earth's climate to increasing atmospheric concentrations of these gases. Data from cores drilled in polar ice sheets show a remarkable correlation between past glacial-interglacial temperature changes and the inferred atmospheric concentration of gases such as carbon dioxide and methane. These and other palaeoclimate data are used to assess the role of greenhouse gases in explaining past global climate change, and the validity of models predicting the effect of increasing concentrations of such gases in the atmosphere.

Plant eco-physiological responses to multiple environmental and climate changes

Energy Technology Data Exchange (ETDEWEB)

Rost Albert, K.

2009-03-15

}; 6) Photosynthetic capacity were closely linked to growth strategy and rewetting stimulation were closely related to high nitrogen leaf content; 7) Responses to elevated CO{sub 2}, drought and warming could not be deduced from single factor experiments; 8) Ambient UV-B decreased PSII performance despite stimulation of UV-B absorbing compounds in high arctic plants in both short and long term; 9) Ambient UV-B decreased net photosynthesis via effects on PSII performance in combination with effects on Calvin Cycle; 10) Current UV-B level is a important factor affecting high arctic plants, particularly in years with spring advancement induced by warming. In conclusion, the results in this thesis suggest the responses of temperate heath plant photosynthesis to be imitatively linked with plant growth strategy and water relations, and also that the responses of photosynthesis to the important drivers often interacted. Current UV-B levels decreases productivity in high arctic heath plants, and advanced spring in response to warming may lead to further decrease while other climatic changes as elevated CO{sub 2} may negate this. Stimulated productivity of temperate heath plants is likely under the climatic conditions predicted to be prevailing in Denmark anno 2075. (author)

Climatic warming strengthens a positive feedback between alpine shrubs and fire.

Science.gov (United States)

Camac, James S; Williams, Richard J; Wahren, Carl-Henrik; Hoffmann, Ary A; Vesk, Peter A

2017-08-01

Climate change is expected to increase fire activity and woody plant encroachment in arctic and alpine landscapes. However, the extent to which these increases interact to affect the structure, function and composition of alpine ecosystems is largely unknown. Here we use field surveys and experimental manipulations to examine how warming and fire affect recruitment, seedling growth and seedling survival in four dominant Australian alpine shrubs. We found that fire increased establishment of shrub seedlings by as much as 33-fold. Experimental warming also doubled growth rates of tall shrub seedlings and could potentially increase their survival. By contrast, warming had no effect on shrub recruitment, postfire tussock regeneration, or how tussock grass affected shrub seedling growth and survival. These findings indicate that warming, coupled with more frequent or severe fires, will likely result in an increase in the cover and abundance of evergreen shrubs. Given that shrubs are one of the most flammable components in alpine and tundra environments, warming is likely to strengthen an existing feedback between woody species abundance and fire in these ecosystems. © 2017 John Wiley & Sons Ltd.

Temporal response of the tiger salamander (Ambystoma tigrinum to 3,000 years of climatic variation

Directory of Open Access Journals (Sweden)

Long Webb

2005-09-01

Full Text Available Abstract Background Amphibians are sensitive indicators of environmental conditions and show measurable responses, such as changes in phenology, abundance and range limits to local changes in precipitation and temperature regimes. Amphibians offer unique opportunities to study the important ecological and evolutionary implications of responses in life history characteristics to climatic change. We analyzed a late-Holocene fossil record of the Tiger Salamander (Ambystoma tigrinum for evidence of population-level changes in body size and paedomorphosis to climatic change over the last 3000 years. Results We found a significant difference in body size index between paedomorphic and metamorphic individuals during the time interval dominated by the Medieval Warm Period. There is a consistent ratio of paedomorphic to metamorphic specimens through the entire 3000 years, demonstrating that not all life history characteristics of the population were significantly altered by changes in climate on this timescale. Conclusion The fossil record of Ambystoma tigrinum we used spans an ecologically relevant timescale appropriate for understanding population and community response to projected climatic change. The population-level responses we documented are concordant with expectations based on modern environmental studies, and yield insight into population-level patterns across hundreds of generations, especially the independence of different life history characteristics. These conclusions lead us to offer general predictions about the future response of this species based on likely scenarios of climatic warming in the Rocky Mountain region.

Results from the BRACE 1.5 study: Climate change impacts of 1.5 C and 2 C warming

Science.gov (United States)

O'Neill, B. C.; Anderson, B.; Monaghan, A. J.; Ren, X.; Sanderson, B.; Tebaldi, C.

2017-12-01

In 2015, 195 countries negotiated the Paris Agreement on climate change, which set long-term goals of limiting global mean warming to well below 2 C and possibly 1.5 C. This event stimulated substantial scientific interest in climate outcomes and impacts on society associated with those levels of warming. Recently, the first set of global climate model simulations explicitly designed to meet those targets were undertaken with the Community Earth System Model (CESM) for use by the research community (Sanderson et al, accepted). The BRACE 1.5 project models societal impacts from these climate outcomes, combined with assumptions about future socioeconomic conditions according to the Shared Socioeconomic Pathways. These analyses build on a recently completed study of the Benefits of Reduced Anthropogenic Climate changE (BRACE), published as a set of 20 papers in Climatic Change, which examined the difference in impacts between two higher scenarios resulting in about 2.5 C and 3.7 C warming by late this century. BRACE 1.5 consists of a set of six papers to be submitted to a special collection in Environmental Research Letters that takes a similar approach but focuses on impacts at 1.5 and 2 C warming. We ask whether impacts differ substantially between the two climate scenarios, accounting for uncertainty in climate outcomes through the use of initial condition ensembles of CESM simulations, and in societal conditions by using alternative SSP-based development pathways. Impact assessment focuses on the health and agricultural sectors; modeling approaches include the use of a global mutli-region CGE model for economic analysis, both a process-based and an empirical crop model, a model of spatial population change, a model of climatic suitability for the aedes aegypti mosquito, and an epidemiological model of heat-related mortality. A methodological analysis also evaluates the use of climate model emulation techniques for providing climate information sufficient to

Global negative vegetation feedback to climate warming responses of leaf litter decomposition rates in cold biomes.

NARCIS (Netherlands)

Cornelissen, J.H.C.; van Bodegom, P.M.; Aerts, R.; Gallaghan, T.V.; van Logtestijn, R.S.P; Alatalo, J.; Chapin, F.S. III; Gerdol, R.; Gudmundsson, J.; Gwynn-Jones, D.; Hartley, A.E.; Hik, D.S.; Hofgaard, A.; Jonsdottir, I.S.; Karlsson, S.; Klein, J.A.; Laundre, J.; Magnusson, B.; Michelsel, A.; Molau, U.; Onipchenko, V.G.; Quested, H.M.; Sandvik, S.M.; Schmidt, I.K.; Shaver, G.R.; Solhleim, B.; Soudzilovskaia, N.A.; Stenstrom, A.; Tolvanen, A.; Totland, O.; Wada, N.; Welker, J.M.; Zhao, X.; Team, M.O.L.

2007-01-01

Whether climate change will turn cold biomes from large long-term carbon sinks into sources is hotly debated because of the great potential for ecosystem-mediated feedbacks to global climate. Critical are the direction, magnitude and generality of climate responses of plant litter decomposition.

Climate Change or Climate Variability? History, Science and Politics in the Mesoamerican Climate

Directory of Open Access Journals (Sweden)

Daniel Poleo

2016-08-01

Full Text Available Climate variations in Mesoamerica have influenced the development and decay of populations from the earliest human settlements. The present time is no exception; there is no evidence that global warming will impact rainfall in the region, but rather there are important studies showing a response of rainfall to climate variability in the American tropics. Since our tropical region is vulnerable to climate variability, public policies must be congruent to avoid the mistakes of previous generations and achieve, with the help of science, a real progress in the fight against global warming.

Near real time/low latency data collection for climate warming manipulations and an elevated CO2 SPRUCE experiment

Science.gov (United States)

Krassovski, M.; Hanson, P. J.; Riggs, J. S.; Nettles, W. R., IV

2017-12-01

Climate change studies are one of the most important aspects of modern science and related experiments are getting bigger and more complex. One such experiment is the Spruce and Peatland Responses Under Climatic and Environmental Change experiment (SPRUCE, http://mnspruce.ornl.gov) conducted in in northern Minnesota, 40 km north of Grand Rapids, in the USDA Forest Service Marcell Experimental Forest (MEF). The SPRUCE experimental mission is to assess ecosystem-level biological responses of vulnerable, high carbon terrestrial ecosystems to a range of climate warming manipulations and an elevated CO2 atmosphere. This manipulation experiment generates a lot of observational data and requires a reliable onsite data collection system, dependable methods to transfer data to a robust scientific facility, and real-time monitoring capabilities. This presentation shares our experience of establishing near real time/low latency data collection and monitoring system using satellite communication.

Climate and tourism in the Black Forest during the warm season.

Science.gov (United States)

Endler, Christina; Matzarakis, Andreas

2011-03-01

Climate, climate change and tourism all interact. Part of the public discussion about climate change focusses on the tourism sector, with direct and indirect impacts being of equally high relevance. Climate and tourism are closely linked. Thus, climate is a very decisive factor in choices both of destination and of type of journey (active holidays, wellness, and city tours) in the tourism sector. However, whether choices about destinations or types of trip will alter with climate change is difficult to predict. Future climates can be simulated and projected, and the tendencies of climate parameters can be estimated using global and regional climate models. In this paper, the focus is on climate change in the mountainous regions of southwest Germany - the Black Forest. The Black Forest is one of the low mountain ranges where both winter and summer tourism are vulnerable to climate change due to its southern location; the strongest climatic changes are expected in areas covering the south and southwest of Germany. Moreover, as the choice of destination is highly dependent on good weather, a climatic assessment for tourism is essential. Thus, the aim of this study was to estimate climatic changes in mountainous regions during summer, especially for tourism and recreation. The assessment method was based on human-biometeorology as well as tourism-climatologic approaches. Regional climate simulations based on the regional climate model REMO were used for tourism-related climatic analyses. Emission scenarios A1B and B1 were considered for the time period 2021 to 2050, compared to the 30-year base period of 1971-2000, particularly for the warm period of the year, defined here as the months of March-November. In this study, we quantified the frequency, but not the means, of climate parameters. The study results show that global and regional warming is reflected in an increase in annual mean air temperature, especially in autumn. Changes in the spring show a slight negative

Modeling Multi-Reservoir Hydropower Systems in the Sierra Nevada with Environmental Requirements and Climate Warming

Science.gov (United States)

Rheinheimer, David Emmanuel

Hydropower systems and other river regulation often harm instream ecosystems, partly by altering the natural flow and temperature regimes that ecosystems have historically depended on. These effects are compounded at regional scales. As hydropower and ecosystems are increasingly valued globally due to growing values for clean energy and native species as well as and new threats from climate warming, it is important to understand how climate warming might affect these systems, to identify tradeoffs between different water uses for different climate conditions, and to identify promising water management solutions. This research uses traditional simulation and optimization to explore these issues in California's upper west slope Sierra Nevada mountains. The Sierra Nevada provides most of the water for California's vast water supply system, supporting high-elevation hydropower generation, ecosystems, recreation, and some local municipal and agricultural water supply along the way. However, regional climate warming is expected to reduce snowmelt and shift runoff to earlier in the year, affecting all water uses. This dissertation begins by reviewing important literature related to the broader motivations of this study, including river regulation, freshwater conservation, and climate change. It then describes three substantial studies. First, a weekly time step water resources management model spanning the Feather River watershed in the north to the Kern River watershed in the south is developed. The model, which uses the Water Evaluation And Planning System (WEAP), includes reservoirs, run-of-river hydropower, variable head hydropower, water supply demand, and instream flow requirements. The model is applied with a runoff dataset that considers regional air temperature increases of 0, 2, 4 and 6 °C to represent historical, near-term, mid-term and far-term (end-of-century) warming. Most major hydropower turbine flows are simulated well. Reservoir storage is also

On the role of ozone feedback in the ENSO amplitude response under global warming

Science.gov (United States)

Nowack, P. J.; Braesicke, P.; Abraham, N. L.; Pyle, J. A.

2017-12-01

The El Niño-Southern Oscillation (ENSO) in the tropical Pacific is of key importance to global climate and weather. However, climate models still disagree on the ENSO's response under climate change. Here we show that typical model representations of ozone can have a first-order impact on ENSO amplitude projections in climate sensitivity simulations (i.e. standard abrupt 4xCO2). We mainly explain this effect by the lapse rate adjustment of the tropical troposphere to ozone changes in the upper troposphere and lower stratosphere (UTLS) under 4xCO2. The ozone-induced lapse rate changes modify the Walker circulation response to the CO2 forcing and consequently tropical Pacific surface temperature gradients. Therefore, not including ozone feedbacks increases the number of extreme ENSO events in our model. In addition, we demonstrate that even if ozone changes in the tropical UTLS are included in the simulations, the neglect of the ozone response in the middle-upper stratosphere still leads to significantly larger ENSO amplitudes (compared to simulations run with a fully interactive atmospheric chemistry scheme). Climate modeling studies of the ENSO often neglect changes in ozone. Our results imply that this could affect the inter-model spread found in ENSO projections and, more generally, surface climate change simulations. We discuss the additional complexity in quantifying such ozone-related effects that arises from the apparent model dependency of chemistry-climate feedbacks and, possibly, their range of surface climate impacts. In conclusion, we highlight the need to understand better the coupling between ozone, the tropospheric circulation, and climate variability. Reference: Nowack PJ, Braesicke P, Abraham NL, and Pyle JA (2017), On the role of ozone feedback in the ENSO amplitude response under global warming, Geophys. Res. Lett. 44, 3858-3866, doi:10.1002/2016GL072418.

Feedback attribution of the land-sea warming contrast in a global warming simulation of the NCAR CCSM4

International Nuclear Information System (INIS)

Sejas, Sergio A; Albert, Oriene S; Cai, Ming; Deng, Yi

2014-01-01

One of the salient features in both observations and climate simulations is a stronger land warming than sea. This paper provides a quantitative understanding of the main processes that contribute to the land-sea warming asymmetry in a global warming simulation of the NCAR CCSM4. The CO 2 forcing alone warms the surface nearly the same for both land and sea, suggesting that feedbacks are responsible for the warming contrast. Our analysis on one hand confirms that the principal contributor to the above-unity land-to-sea warming ratio is the evaporation feedback; on the other hand the results indicate that the sensible heat flux feedback has the largest land-sea warming difference that favors a greater ocean than land warming. Therefore, the results uniquely highlight the importance of other feedbacks in establishing the above-unity land-to-sea warming ratio. Particularly, the SW cloud feedback and the ocean heat storage in the transient response are key contributors to the greater warming over land than sea. (letter)

The Role of Atmospheric Heating over the South China Sea and Western Pacific Regions in Modulating Asian Summer Climate under the Global Warming Background

Science.gov (United States)

He, B.

2015-12-01

Global warming is one of the most significant climate change signals at the earth's surface. However, the responses of monsoon precipitation to global warming show very distinct regional features, especially over the South China Sea (SCS) and surrounding regions during boreal summer. To understand the possible dynamics in these specific regions under the global warming background, the changes in atmospheric latent heating and their possible influences on global climate are investigated by both observational diagnosis and numerical sensitivity simulations. Results indicate that summertime latent heating has intensified in the SCS and western Pacific, accompanied by increased precipitation, cloud cover, lower-tropospheric convergence, and decreased sea level pressure. Sensitivity experiments show that middle and upper tropospheric heating causes an east-west feedback pattern between SCS-western Pacific and South Asia, which strengthens the South Asian High in the upper troposphere and moist convergence in the lower troposphere, consequently forcing a descending motion and adiabatic warming over continental South Asia and leading to a warm and dry climate. When air-sea interaction is considered, the simulation results are overall more similar to observations, and in particular the bias of precipitation over the Indian Ocean simulated by AGCMs has been reduced. The results highlight the important role of latent heating in adjusting the changes in sea surface temperature through atmospheric dynamics.

Data-Constrained Projections of Methane Fluxes in a Northern Minnesota Peatland in Response to Elevated CO2 and Warming

Science.gov (United States)

Ma, Shuang; Jiang, Jiang; Huang, Yuanyuan; Shi, Zheng; Wilson, Rachel M.; Ricciuto, Daniel; Sebestyen, Stephen D.; Hanson, Paul J.; Luo, Yiqi

2017-11-01

Large uncertainties exist in predicting responses of wetland methane (CH4) fluxes to future climate change. However, sources of the uncertainty have not been clearly identified despite the fact that methane production and emission processes have been extensively explored. In this study, we took advantage of manual CH4 flux measurements under ambient environment from 2011 to 2014 at the Spruce and Peatland Responses Under Changing Environments (SPRUCE) experimental site and developed a data-informed process-based methane module. The module was incorporated into the Terrestrial ECOsystem (TECO) model before its parameters were constrained with multiple years of methane flux data for forecasting CH4 emission under five warming and two elevated CO2 treatments at SPRUCE. We found that 9°C warming treatments significantly increased methane emission by approximately 400%, and elevated CO2 treatments stimulated methane emission by 10.4%-23.6% in comparison with ambient conditions. The relative contribution of plant-mediated transport to methane emission decreased from 96% at the control to 92% at the 9°C warming, largely to compensate for an increase in ebullition. The uncertainty in plant-mediated transportation and ebullition increased with warming and contributed to the overall changes of emissions uncertainties. At the same time, our modeling results indicated a significant increase in the emitted CH4:CO2 ratio. This result, together with the larger warming potential of CH4, will lead to a strong positive feedback from terrestrial ecosystems to climate warming. The model-data fusion approach used in this study enabled parameter estimation and uncertainty quantification for forecasting methane fluxes.

The influence of life history traits on the phenological response of British butterflies to climate variability since the late-19th century

OpenAIRE

Brooks, Stephen J.; Self, Angela; Powney, Gary D.; Pearse, William D.; Penn, Malcolm; Paterson, Gordon L.J.

2017-01-01

Many species of plants and animals have advanced their phenology in response to climate warming in recent decades. Most of the evidence available for these shifts is based on data from the last few decades, a period coinciding with rapid climate warming. Baseline data is required to put these recent phenological changes in a long-term context. We analysed the phenological response of 51 resident British butterfly species using data from 83 500 specimens in the collections of the Natural Histo...

Climate, lies and propaganda

International Nuclear Information System (INIS)

Arezki, A.

2010-01-01

There is today a strong scientific controversy between alarmist climatologists who consider that the human activities are responsible of the global warming, and climate-skeptics for whom the climate change has a natural origin. Without any passion and far away from any lobby, the author proposes a radical analysis of the situation by answering the essential questions: what is the real extent of global warming? Is this warming unprecedented? Should we alarm for? Except human activities, what other serious hypotheses could explain the actual climatic change? Beside the scientific aspects, this book reveals also the real political, economical and media-staged aspects of the global warming debate. (J.S.)

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

Peatland Microbial Carbon Use Under Warming using Isotopic Fractionation

Science.gov (United States)

Gutknecht, J.

2016-12-01

Peatlands are a critical natural resource, especially in their role as carbon sinks. Most of the world's peatlands are located in Northern ecosystems where the climate is changing at a rapid pace, and there is great interest and concern with how climate change will influence them. Although studies regarding the response of peatlands to climate change have emerged, the microbial mediation of C cycling in these systems is still less well understood. In this study, 13CPLFA analysis was used to characterize the microbial community and it's carbon use at the Spruce and Peatland Responses Under Climatic and Environmental Change (SPRUCE) Project. The SPRUCE project is an extensive study of the response of peatlands to climatic manipulation in the Marcell Experimental Forest in northern Minnesota. Heating rods were installed in peatland plots where peat is being warmed at several levels including ambient, +2.5, +4.5, +6.75, and +9 degrees Celsius, at a depth of 3 meters, beginning July of 2014. Samples were taken June 2014, September 2014, and June 2015, throughout the depth profile. We found very high microbial, and especially fungal growth at shallow depths, owing in part to the influence of fungal-like lipids present in Sphagnum stems, and in part to dense mycorrhizal colonization in shrub and tree species. Isotopic data shows that microbial biomass has an enriched δ13C lower in the peat profile, indicating as expected that microbes at depth utilize older carbon or carbon more enriched in 13C. The increase over depth in the δ13C signature may also reflect the increased dominance of pre-industrial carbon that is more enriched in 13C. In this early period of warming we did not see clear effects of warming, either due to the highly heterogeneous microbial growth across the bog, or to the short term deep warming only. We expect that with the initiation of aboveground warming in July 2016, warming will begin to show stronger effects on microbial C cycling.

Improving the effectiveness of communication about climate science: Insights from the "Global Warming's Six Americas" audience segmentation research project

Science.gov (United States)

Maibach, E.; Roser-Renouf, C.

2011-12-01

That the climate science community has not been entirely effective in sharing what it knows about climate change with the broader public - and with policy makers and organizations that should be considering climate change when making decisions - is obvious. Our research shows that a large majority of the American public trusts scientists (76%) and science-based agencies (e.g., 76% trust NOAA) as sources of information about climate change. Yet, despite the widespread agreement in the climate science community that the climate is changing as a result of human activity, only 64% of the public understand that the world's average temperature has been increasing (and only about half of them are sure), less than half (47%) understand that the warming is caused mostly by human activity, and only 39% understand that most scientists think global warming is happening (in fact, only 13% understand that the large majority of climate scientists think global warming is happening). Less obvious is what the climate science community should do to become more effective in sharing what it knows. In this paper, we will use evidence from our "Global Warming's Six Americas" audience segmentation research project to suggest ways that individual climate scientists -- and perhaps more importantly, ways in which climate science agencies and professional societies -- can enhance the effectiveness of their communication efforts. We will conclude by challenging members of the climate science community to identify and convey "simple, clear messages, repeated often, by a variety of trusted sources" - an approach to communication repeatedly shown to be effective by the public health community.

Climate warming and humans played different roles in triggering Late Quaternary extinctions in east and west Eurasia.

Science.gov (United States)

Wan, Xinru; Zhang, Zhibin

2017-03-29

Climate change and humans are proposed as the two key drivers of total extinction of many large mammals in the Late Pleistocene and Early Holocene, but disentangling their relative roles remains challenging owing to a lack of quantitative evaluation of human impact and climate-driven distribution changes on the extinctions of these large mammals in a continuous temporal-spatial dimension. Here, our analyses showed that temperature change had significant effects on mammoth (genus Mammuthus ), rhinoceros (Rhinocerotidae), horse (Equidae) and deer (Cervidae). Rapid global warming was the predominant factor driving the total extinction of mammoths and rhinos in frigid zones from the Late Pleistocene and Early Holocene. Humans showed significant, negative effects on extirpations of the four mammalian taxa, and were the predominant factor causing the extinction or major extirpations of rhinos and horses. Deer survived both rapid climate warming and extensive human impacts. Our study indicates that both the current rates of warming and range shifts of species are much faster than those from the Late Pleistocene to Holocene. Our results provide new insight into the extinction of Late Quaternary megafauna by demonstrating taxon-, period- and region-specific differences in extinction drivers of climate change and human disturbances, and some implications about the extinction risk of animals by recent and ongoing climate warming. © 2017 The Author(s).

Global warming: Design of a flow-through shallow lake mesocosm climate experiment

DEFF Research Database (Denmark)

Liboriussen, L.; Landkildehus, F.; Meerhoff, M.

2005-01-01

design details, operating characteristics, and background information on a currently operating experimental flow-through mesocosm system that allows investigation of the interactions between simulated climate warming and eutrophication and their impacts on biological structure and ecosystem processes...

Impacts of climate change and climate extremes on major crops productivity in China at a global warming of 1.5 and 2.0 °C

Science.gov (United States)

Chen, Yi; Zhang, Zhao; Tao, Fulu

2018-05-01

A new temperature goal of holding the increase in global average temperature well below 2 °C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5 °C above pre-industrial levels has been established in the Paris Agreement, which calls for an understanding of climate risk under 1.5 and 2.0 °C warming scenarios. Here, we evaluated the effects of climate change on growth and productivity of three major crops (i.e. maize, wheat, rice) in China during 2106-2115 in warming scenarios of 1.5 and 2.0 °C using a method of ensemble simulation with well-validated Model to capture the Crop-Weather relationship over a Large Area (MCWLA) family crop models, their 10 sets of optimal crop model parameters and 70 climate projections from four global climate models. We presented the spatial patterns of changes in crop growth duration, crop yield, impacts of heat and drought stress, as well as crop yield variability and the probability of crop yield decrease. Results showed that climate change would have major negative impacts on crop production, particularly for wheat in north China, rice in south China and maize across the major cultivation areas, due to a decrease in crop growth duration and an increase in extreme events. By contrast, with moderate increases in temperature, solar radiation, precipitation and atmospheric CO2 concentration, agricultural climate resources such as light and thermal resources could be ameliorated, which would enhance canopy photosynthesis and consequently biomass accumulations and yields. The moderate climate change would slightly worsen the maize growth environment but would result in a much more appropriate growth environment for wheat and rice. As a result, wheat, rice and maize yields would change by +3.9 (+8.6), +4.1 (+9.4) and +0.2 % (-1.7 %), respectively, in a warming scenario of 1.5 °C (2.0 °C). In general, the warming scenarios would bring more opportunities than risks for crop development and food

Arctic plants are capable of sustained responses to long-term warming

Directory of Open Access Journals (Sweden)

Robert T. Barrett

2016-05-01

Full Text Available Previous studies have shown that Arctic plants typically respond to warming with increased growth and reproductive effort and accelerated phenology, and that the magnitude of these responses is likely to change over time. We investigated the effects of long-term experimental warming on plant growth (leaf length and reproduction (inflorescence height, reproductive phenology and reproductive effort using 17–19 years of measurements collected as part of the International Tundra Experiment (ITEX at sites near Barrow and Atqasuk, Alaska. During the study period, linear regressions indicated non-significant tendencies towards warming air temperatures at our study sites. Results of our meta-analyses on the effect size of experimental warming (calculated as Hedges’ d indicated species generally responded to warming by increasing inflorescence height, increasing leaf length and flowering earlier, while reproductive effort did not respond consistently. Using weighted least-squares regressions on effect sizes, we found a significant trend towards dampened response to experimental warming over time for reproductive phenology. This tendency was consistent, though non-significant, across all traits. A separate analysis revealed significant trends towards reduced responses to experimental warming during warmer summers for all traits. We therefore propose that tendencies towards dampened plant responses to experimental warming over time are the result of regional warming. These results show that Arctic plants are capable of sustained responses to warming over long periods of time but also suggest that, as the region continues to warm, factors such as nutrient availability, competition and herbivory will become more limiting to plant growth and reproduction than temperature.

Prediction of abundance of forest spiders according to climate warming in South Korea

Directory of Open Access Journals (Sweden)

Tae-Sung Kwon

2014-06-01

Full Text Available Distribution of spiders will be changed as climate warms. Abundance of spider species was predicted nationwide in South Korea. Abundance of spiders was projected using temperature species distribution model based on a nationwide data (366 forest sites according to climate change scenario RCP 4.5 and 8.5. The model predicts that 9 out of 17 species will increase in abundance while 8 species will decrease. Based on this finding, a qualitative prediction (increase or decrease was conducted on the species with more than 1% occurrence: 68 species are expected to decrease, 9 to increase, and 8 to change a little. In pooled estimation, 76 species (75% are expected to decrease, 18 species (18% to increase, and by 8 species (8% to have little change. The projection indicates that majority of spider species will decrease, but minority of species will increase as climate warms, suggesting great increase of remained species in lowlands.

Recurrent sublethal warming reduces embryonic survival, inhibits juvenile growth, and alters species distribution projections under climate change.

Science.gov (United States)

Carlo, Michael A; Riddell, Eric A; Levy, Ofir; Sears, Michael W

2018-01-01

The capacity to tolerate climate change often varies across ontogeny in organisms with complex life cycles. Recently developed species distribution models incorporate traits across life stages; however, these life-cycle models primarily evaluate effects of lethal change. Here, we examine impacts of recurrent sublethal warming on development and survival in ecological projections of climate change. We reared lizard embryos in the laboratory under temperature cycles that simulated contemporary conditions and warming scenarios. We also artificially warmed natural nests to mimic laboratory treatments. In both cases, recurrent sublethal warming decreased embryonic survival and hatchling sizes. Incorporating survivorship results into a mechanistic species distribution model reduced annual survival by up to 24% compared to models that did not incorporate sublethal warming. Contrary to models without sublethal effects, our model suggests that modest increases in developmental temperatures influence species ranges due to effects on survivorship. © 2017 John Wiley & Sons Ltd/CNRS.

Impact of global warming on the geobotanic zones: an experiment with a statistical-dynamical climate model

Energy Technology Data Exchange (ETDEWEB)

Franchito, Sergio H.; Brahmananda Rao, V. [Instituto Nacional de Pesquisas Espaciais, Centro de Ciencia do Sistema Terrestre, CCST, Sau Paulo, SP (Brazil); Moraes, E.C. [Instituto Nacional de Pesquisas Espaciais, Divisao de Sensoriamento Remoto, DSR, Sau Paulo, SP (Brazil)

2011-11-15

In this study, a zonally-averaged statistical climate model (SDM) is used to investigate the impact of global warming on the distribution of the geobotanic zones over the globe. The model includes a parameterization of the biogeophysical feedback mechanism that links the state of surface to the atmosphere (a bidirectional interaction between vegetation and climate). In the control experiment (simulation of the present-day climate) the geobotanic state is well simulated by the model, so that the distribution of the geobotanic zones over the globe shows a very good agreement with the observed ones. The impact of global warming on the distribution of the geobotanic zones is investigated considering the increase of CO{sub 2} concentration for the B1, A2 and A1FI scenarios. The results showed that the geobotanic zones over the entire earth can be modified in future due to global warming. Expansion of subtropical desert and semi-desert zones in the Northern and Southern Hemispheres, retreat of glaciers and sea-ice, with the Arctic region being particularly affected and a reduction of the tropical rainforest and boreal forest can occur due to the increase of the greenhouse gases concentration. The effects were more pronounced in the A1FI and A2 scenarios compared with the B1 scenario. The SDM results confirm IPCC AR4 projections of future climate and are consistent with simulations of more complex GCMs, reinforcing the necessity of the mitigation of climate change associated to global warming. (orig.)

Global Warming Blame the Sun

CERN Document Server

Calder, N

1997-01-01

Concern about climate change reaches a political peak at a UN conference in Kyoto, 1-10 December, but behind the scenes the science is in turmoil. A challenge to the hypothesis that greenhouse gases are responsible for global warming comes from the discovery that cosmic rays from the Galaxy are involved in making clouds (Svensmark and Friis-Christensen, 1997). During the 20th Century the wind from the Sun has grown stronger and the count of cosmic rays has diminished. With fewer clouds, the EarthÕs surface has warmed up. This surprising mechanism explains the link between the Sun and climate change that astronomers and geophysicists have suspected for 200 years.

Differential behavioural responses to venlafaxine exposure route, warming and acidification in juvenile fish (Argyrosomus regius).

Science.gov (United States)

Maulvault, Ana Luísa; Santos, Lúcia H M L M; Paula, José Ricardo; Camacho, Carolina; Pissarra, Vasco; Fogaça, Fabiola; Barbosa, Vera; Alves, Ricardo; Ferreira, Pedro Pousão; Barceló, Damià; Rodriguez-Mozaz, Sara; Marques, António; Diniz, Mário; Rosa, Rui

2018-09-01

Antidepressants, such as venlafaxine (VFX), which are considered emerging environmental pollutants, are increasingly more present in the marine environment, and recent evidence suggest that they might have adverse effects on fish behaviour. Furthermore, altered environmental conditions associated to climate change (e.g. warming and acidification) can also have a determinant role on fish behaviour, fitness and survival. Yet, the underlying interactions between these environmental stressors (pharmaceuticals exposure and climate change) are still far from being fully understood. The aim of this study was to assess behavioural responses (in juvenile meagre (Argyrosomus regius) exposed to VFX via water ([VFX] ~20μgL -1 ) and via dietary sources ([VFX] ~160μgkg -1 dry weight), as well as to increased temperature (ΔT°C=+5°C) and high CO 2 levels (ΔpCO 2 ~1000μatm; equivalent to ΔpH=-0.4units). Overall, VFX bioaccumulation in fish plasma was enhanced under the combination of warming and acidification. VFX triggered fish exploration, whereas fish activity and shoal cohesion were reduced. Acidification alone decreased fish exploration and shoal cohesion, and reversed fish preference to turn leftwards compared to control conditions. Such alterations were further enhanced by VFX exposure. The combination of warming and acidification also reduced shoal cohesion and loss of lateralization, regardless of VFX exposure. The distinct behaviour observed when VFX contamination, acidification and warming acted alone or in combination highlighted the need to consider the likely interactive effects of seawater warming and acidification in future research regarding the toxicological aspects of chemical contaminants. Copyright © 2018. Published by Elsevier B.V.

Global Farm Animal Production and Global Warming: Impacting and Mitigating Climate Change

OpenAIRE

Koneswaran, Gowri; Nierenberg, Danielle

2008-01-01

Background The farm animal sector is the single largest anthropogenic user of land, contributing to many environmental problems, including global warming and climate change. Objectives The aim of this study was to synthesize and expand upon existing data on the contribution of farm animal production to climate change. Methods We analyzed the scientific literature on farm animal production and documented greenhouse gas (GHG) emissions, as well as various mitigation strategies. Discussions An a...

500-year climate cycles stacking of recent centennial warming documented in an East Asian pollen record

Science.gov (United States)

Xu, Deke; Lu, Houyuan; Chu, Guoqiang; Wu, Naiqin; Shen, Caiming; Wang, Can; Mao, Limi

2014-01-01

Here we presented a high-resolution 5350-year pollen record from a maar annually laminated lake in East Asia (EA). Pollen record reflected the dynamics of vertical vegetation zones and temperature change. Spectral analysis on pollen percentages/concentrations of Pinus and Quercus, and a temperature proxy, revealed ~500-year quasi-periodic cold-warm fluctuations during the past 5350 years. This ~500-year cyclic climate change occurred in EA during the mid-late Holocene and even the last 150 years dominated by anthropogenic forcing. It was almost in phase with a ~500-year periodic change in solar activity and Greenland temperature change, suggesting that ~500-year small variations in solar output played a prominent role in the mid-late Holocene climate dynamics in EA, linked to high latitude climate system. Its last warm phase might terminate in the next several decades to enter another ~250-year cool phase, and thus this future centennial cyclic temperature minimum could partially slow down man-made global warming. PMID:24402348

Paris Agreement climate proposals need a boost to keep warming well below 2 °C.

Science.gov (United States)

Rogelj, Joeri; den Elzen, Michel; Höhne, Niklas; Fransen, Taryn; Fekete, Hanna; Winkler, Harald; Schaeffer, Roberto; Sha, Fu; Riahi, Keywan; Meinshausen, Malte

2016-06-30

The Paris climate agreement aims at holding global warming to well below 2 degrees Celsius and to "pursue efforts" to limit it to 1.5 degrees Celsius. To accomplish this, countries have submitted Intended Nationally Determined Contributions (INDCs) outlining their post-2020 climate action. Here we assess the effect of current INDCs on reducing aggregate greenhouse gas emissions, its implications for achieving the temperature objective of the Paris climate agreement, and potential options for overachievement. The INDCs collectively lower greenhouse gas emissions compared to where current policies stand, but still imply a median warming of 2.6-3.1 degrees Celsius by 2100. More can be achieved, because the agreement stipulates that targets for reducing greenhouse gas emissions are strengthened over time, both in ambition and scope. Substantial enhancement or over-delivery on current INDCs by additional national, sub-national and non-state actions is required to maintain a reasonable chance of meeting the target of keeping warming well below 2 degrees Celsius.

Responses of terrestrial ecosystems' net primary productivity to future regional climate change in China.

Science.gov (United States)

Zhao, Dongsheng; Wu, Shaohong; Yin, Yunhe

2013-01-01

The impact of regional climate change on net primary productivity (NPP) is an important aspect in the study of ecosystems' response to global climate change. China's ecosystems are very sensitive to climate change owing to the influence of the East Asian monsoon. The Lund-Potsdam-Jena Dynamic Global Vegetation Model for China (LPJ-CN), a global dynamical vegetation model developed for China's terrestrial ecosystems, was applied in this study to simulate the NPP changes affected by future climate change. As the LPJ-CN model is based on natural vegetation, the simulation in this study did not consider the influence of anthropogenic activities. Results suggest that future climate change would have adverse effects on natural ecosystems, with NPP tending to decrease in eastern China, particularly in the temperate and warm temperate regions. NPP would increase in western China, with a concentration in the Tibetan Plateau and the northwest arid regions. The increasing trend in NPP in western China and the decreasing trend in eastern China would be further enhanced by the warming climate. The spatial distribution of NPP, which declines from the southeast coast to the northwest inland, would have minimal variation under scenarios of climate change.

Responses of terrestrial ecosystems' net primary productivity to future regional climate change in China.

Directory of Open Access Journals (Sweden)

Dongsheng Zhao

Full Text Available The impact of regional climate change on net primary productivity (NPP is an important aspect in the study of ecosystems' response to global climate change. China's ecosystems are very sensitive to climate change owing to the influence of the East Asian monsoon. The Lund-Potsdam-Jena Dynamic Global Vegetation Model for China (LPJ-CN, a global dynamical vegetation model developed for China's terrestrial ecosystems, was applied in this study to simulate the NPP changes affected by future climate change. As the LPJ-CN model is based on natural vegetation, the simulation in this study did not consider the influence of anthropogenic activities. Results suggest that future climate change would have adverse effects on natural ecosystems, with NPP tending to decrease in eastern China, particularly in the temperate and warm temperate regions. NPP would increase in western China, with a concentration in the Tibetan Plateau and the northwest arid regions. The increasing trend in NPP in western China and the decreasing trend in eastern China would be further enhanced by the warming climate. The spatial distribution of NPP, which declines from the southeast coast to the northwest inland, would have minimal variation under scenarios of climate change.

New Approaches to FIA data for understanding distribution, abundance, and response to climate change

Science.gov (United States)

Kai Zhu; Souparno Ghosh; Alan E. Gelfand; James S. Clark

2012-01-01

We are using Forest Inventory and Analysis data to examine evidence for tree responses to climate change. By comparing seedling and tree occurrence data, we found that there is not yet evidence that tree populations in the eastern half of the United States are shifting geographic ranges to higher latitude in response to warming temperature. We are developing novel...

Changes in Intense Precipitation Events in West Africa and the central U.S. under Global Warming

Energy Technology Data Exchange (ETDEWEB)

Cook, Kerry H. [Univ. of Texas, Austin, TX (United States); Vizy, Edward [Univ. of Texas, Austin, TX (United States)

2016-02-08

The purpose of the proposed project is to improve our understanding of the physical processes and large-scale connectivity of changes in intense precipitation events (high rainfall rates) under global warming in West Africa and the central U.S., including relationships with low-frequency modes of variability. This is in response to the requested subject area #2 “simulation of climate extremes under a changing climate … to better quantify the frequency, duration, and intensity of extreme events under climate change and elucidate the role of low frequency climate variability in modulating extremes.” We will use a regional climate model and emphasize an understanding of the physical processes that lead to an intensification of rainfall. The project objectives are as follows: 1. Understand the processes responsible for simulated changes in warm-season rainfall intensity and frequency over West Africa and the Central U.S. associated with greenhouse gas-induced global warming 2. Understand the relationship between changes in warm-season rainfall intensity and frequency, which generally occur on regional space scales, and the larger-scale global warming signal by considering modifications of low-frequency modes of variability. 3. Relate changes simulated on regional space scales to global-scale theories of how and why atmospheric moisture levels and rainfall should change as climate warms.

Warm-water coral reefs and climate change.

Science.gov (United States)

Spalding, Mark D; Brown, Barbara E

2015-11-13

Coral reefs are highly dynamic ecosystems that are regularly exposed to natural perturbations. Human activities have increased the range, intensity, and frequency of disturbance to reefs. Threats such as overfishing and pollution are being compounded by climate change, notably warming and ocean acidification. Elevated temperatures are driving increasingly frequent bleaching events that can lead to the loss of both coral cover and reef structural complexity. There remains considerable variability in the distribution of threats and in the ability of reefs to survive or recover from such disturbances. Without significant emissions reductions, however, the future of coral reefs is increasingly bleak. Copyright © 2015, American Association for the Advancement of Science.

Climate Impacts in Europe Under +1.5°C Global Warming

NARCIS (Netherlands)

Jacob, Daniela; Kotova, Lola; Teichmann, Claas; Sobolowski, Stefan P.; Vautard, Robert; Donnelly, Chantal; Koutroulis, Aristeidis G.; Grillakis, Manolis G.; Tsanis, Ioannis K.; Damm, Andrea; Sakalli, Abdulla; Vliet, van Michelle T.H.

2018-01-01

The Paris Agreement of the United Nations Framework Convention on Climate Change aims not only at avoiding +2°C warming (and even limit the temperature increase further to +1.5°C), but also sets long-term goals to guide mitigation. Therefore, the best available science is required to inform

The asymmetric impact of global warming on US drought types and distributions in a large ensemble of 97 hydro-climatic simulations.

Science.gov (United States)

Huang, Shengzhi; Leng, Guoyong; Huang, Qiang; Xie, Yangyang; Liu, Saiyan; Meng, Erhao; Li, Pei

2017-07-19

Projection of future drought is often involved large uncertainties from climate models, emission scenarios as well as drought definitions. In this study, we investigate changes in future droughts in the conterminous United States based on 97 1/8 degree hydro-climate model projections. Instead of focusing on a specific drought type, we investigate changes in meteorological, agricultural, and hydrological drought as well as the concurrences. Agricultural and hydrological droughts are projected to become more frequent with increase in global mean temperature, while less meteorological drought is expected. Changes in drought intensity scale linearly with global temperature rises under RCP8.5 scenario, indicating the potential feasibility to derive future drought severity given certain global warming amount under this scenario. Changing pattern of concurrent droughts generally follows that of agricultural and hydrological droughts. Under the 1.5 °C warming target as advocated in recent Paris agreement, several hot spot regions experiencing highest droughts are identified. Extreme droughts show similar patterns but with much larger magnitude than the climatology. This study highlights the distinct response of droughts of various types to global warming and the asymmetric impact of global warming on drought distribution resulting in a much stronger influence on extreme drought than on mean drought.

The Frustrating Lives of Climate Scientists - 45 Years of Warm, Cold, Wet and Dry

Science.gov (United States)

Toon, O. B.; Hartwick, V.; Urata, R. A.

2016-12-01

Mariner 9 arrived at Mars in November 1971, where it revealed giant volcanoes and dry river valleys some of which originated from rainfall or runoff. Some geologists think there were oceans, tidal waves, craters that filled to their rims and then overflowed or didn't overflow, and river deltas reaching into the ancient seas and lakes. Climate scientists have stumbled through a 45 year-long chain of failed explanations for these geologic data. CO2 in greater abundance than now is likely involved, but not sufficient. Adding CH4 , CO2 clouds, or SO2 have faltered on further study. Three ideas are still being kicked around, two of which are able to make Mars warm, but may have geologic issues. First, is the idea of adding H2 to the CO2, which warms sufficiently in climate models. However, the large quantities needed are a challenge to outgassing models. Second, is impacts, the largest of which would mobilize most of the water in the regolith. Geologists object that the water from impacts would not last long enough to carve rivers. However, no one has explored the concurrent generation of the regolith by these impacts, which would create a loose, easily erodible surface. Are the rivers all in ancient regolith? If some rivers are in bedrock it would be harder to explain by impacts. Finally, impacts may triggered water/cloud greenhouses. Such a climate state would be long lasting, requires only a modest background atmosphere of carbon dioxide, and would fade away when the carbon dioxide dropped below a few hundred mbar. However, not all climate models have been able to produce such water driven greenhouse warming. In this talk I will outline the history of these climate models, point to evidence that might discriminate between them, describe how the water greenhouse models work or don't work, and suggest some new projects that might be done to decide just how warm and wet Mars may have been.

Scenario dependence of future changes in climate extremes under 1.5 °C and 2 °C global warming.

Science.gov (United States)

Wang, Zhili; Lin, Lei; Zhang, Xiaoye; Zhang, Hua; Liu, Liangke; Xu, Yangyang

2017-04-20

The 2015 Paris Agreement aims to limit global warming below 2 °C and pursue efforts to even limit it to 1.5 °C relative to pre-industrial levels. Decision makers need reliable information on the impacts caused by these warming levels for climate mitigation and adaptation measures. We explore the changes in climate extremes, which are closely tied to economic losses and casualties, under 1.5 °C and 2 °C global warming and their scenario dependence using three sets of ensemble global climate model simulations. A warming of 0.5 °C (from 1.5 °C to 2 °C) leads to significant increases in temperature and precipitation extremes in most regions. However, the projected changes in climate extremes under both warming levels highly depend on the pathways of emissions scenarios, with different greenhouse gas (GHG)/aerosol forcing ratio and GHG levels. Moreover, there are multifold differences in several heavily polluted regions, among the scenarios, in the changes in precipitation extremes due to an additional 0.5 °C warming from 1.5 °C to 2 °C. Our results demonstrate that the chemical compositions of emissions scenarios, not just the total radiative forcing and resultant warming level, must be considered when assessing the impacts of global 1.5/2 °C warming.

Terrestrial water flux responses to global warming in tropical rainforest areas

Science.gov (United States)

Lan, Chia-Wei; Lo, Min-Hui; Chou, Chia; Kumar, Sanjiv

2016-05-01

Precipitation extremes are expected to become more frequent in the changing global climate, which may considerably affect the terrestrial hydrological cycle. In this study, Coupled Model Intercomparison Project Phase 5 archives have been examined to explore the changes in normalized terrestrial water fluxes (precipitation minus evapotranspiration minus total runoff, divided by the precipitation climatology) in three tropical rainforest areas: Maritime Continent, Congo, and Amazon. Results show that a higher frequency of intense precipitation events is predicted for the Maritime Continent in the future climate than in the present climate, but not for the Amazon or Congo rainforests. Nonlinear responses to extreme precipitation lead to a reduced groundwater recharge and a proportionately greater amount of direct runoff, particularly for the Maritime Continent, where both the amount and intensity of precipitation increase under global warming. We suggest that the nonlinear response is related to the existence of a higher near-surface soil moisture over the Maritime Continent than that over the Amazon and Congo rainforests. The wetter soil over the Maritime Continent also leads to an increased subsurface runoff. Thus, increased precipitation extremes and concomitantly reduced terrestrial water fluxes lead to an intensified hydrological cycle for the Maritime Continent. This has the potential to result in a strong temporal heterogeneity in soil water distribution affecting the ecosystem of the rainforest region and increasing the risk of flooding and/or landslides.

Anticyclonic atmospheric circulation as an analogue for the warm and dry mid-Holocene summer climate in central Scandinavia

Directory of Open Access Journals (Sweden)

K. Antonsson

2008-10-01

Full Text Available Climate reconstructions from central Scandinavia suggest that annual and summer temperatures were rising during the early Holocene and reached their maximum after 8000 cal yr BP. The period with highest temperatures was characterized by increasingly low lake-levels and dry climate, with driest and warmest conditions at about 7000 to 5000 cal yr BP. We compare the reconstructed climate pattern with simulations of a climate model for the last 9000 years and show that the model, which is predominantly driven by solar insolation patterns, suggests less prominent mid-Holocene dry and warm period in Scandinavia than the reconstructions. As an additional explanation for the reconstructed climate, we argue that the trend from the moist early Holocene towards dry and warm mid-Holocene was caused by a changing atmospheric circulation pattern with a mid-Holocene dominance of summer-time anticyclonic circulation. An extreme case of the anticyclonic conditions is the persistent blocking high, an atmospheric pressure pattern that at present often causes long spells of particularly dry and warm summer weather, or "Indian summers". The argument is tested with daily instrumental temperature and precipitation records in central Sweden and an objective circulation classification based on surface air pressure over the period 1900–2002. We conclude that the differences between the precipitation and temperature climates under anticyclonic and non-anticyclonic conditions are significant. Further, warm and dry combination, as indicated by mid-Holocene reconstructions, is a typical pattern under anticyclonic conditions. These results indicate that the presented hypothesis for the mid-Holocene climate is likely valid.

Integrating geological archives and climate models for the mid-Pliocene warm period.

Science.gov (United States)

Haywood, Alan M; Dowsett, Harry J; Dolan, Aisling M

2016-02-16

The mid-Pliocene Warm Period (mPWP) offers an opportunity to understand a warmer-than-present world and assess the predictive ability of numerical climate models. Environmental reconstruction and climate modelling are crucial for understanding the mPWP, and the synergy of these two, often disparate, fields has proven essential in confirming features of the past and in turn building confidence in projections of the future. The continual development of methodologies to better facilitate environmental synthesis and data/model comparison is essential, with recent work demonstrating that time-specific (time-slice) syntheses represent the next logical step in exploring climate change during the mPWP and realizing its potential as a test bed for understanding future climate change.

Climate changes instead of global warming

Directory of Open Access Journals (Sweden)

Radovanović Milan M.

2014-01-01

Full Text Available Air temperature changes on Earth in recent years are the subject of numerous and increasingly interdisciplinary research. In contrast to, conditionally speaking, generally accepted views that these changes are conditioned primarily by anthropogenic activity, more results appear to suggest that it is dominant natural processes about. Whether because of the proven existence of areas in which downtrends are registered or the stagnation of air temperature, as opposed to areas where the increase is determined, in scientific papers, as well as the media, the increasingly present is the use of the term climate changes instead of the global warming. In this paper, we shall try to present arguments for the debate relating to the official view of the IPCC, as well as research indicating the opposite view.

The Climate Effects of Deforestation the Amazon Rainforest under Global Warming Conditions

Science.gov (United States)

Werth, D.; Avissar, R.

2006-12-01

Replacement of tropical rainforests has been observed to have a strong drying effect in Amazon simulations, with effects reaching high into the atmospheric column and into the midlatitudes. The drying effects of deforestation, however, can be moderated by the effects of global warming, which should accelerate the hydrologic cycle of the Amazon. The effects of a prescribed, time-varying Amazon deforestation done in conjunction with a steady, moderate increase in CO2 concentrations are determined using a climate model. The model agrees with previous studies when each forcing is applied individually - compared to a control run, Amazon deforestation decreases the local precipitation and global warming increases it. When both are applied, however, the precipitation and other hydrologic variables decrease, but to a lesser extent than when deforestation alone was applied. In effect, the two effects act opposite to one another and bring the simulated climate closer to that of the control.

Responses of Winter Wheat Yields to Warming-Mediated Vernalization Variations Across Temperate Europe

Directory of Open Access Journals (Sweden)

Xiuchen Wu

2017-10-01

Full Text Available Rapid climate warming, with much higher warming rates in winter and spring, could affect the vernalization fulfillment, a critical process for induction of crop reproductive growth and consequent grain filling in temperate winter crops. However, regional observational evidence of the effects of historical warming-mediated vernalization variations on temperate winter crop yields is lacking. Here, we statistically quantified the interannual sensitivity of winter wheat yields to vernalization degree days (VDD during 1975–2009 and its spatial relationship with multi-year mean VDD over temperate Europe (TE, using EUROSTAT crop yield statistics, observed and simulated crop phenology data and gridded daily climate data. Our results revealed a pervasively positive interannual sensitivity of winter wheat yields to variations in VDD (γVDD over TE, with a mean γVDD of 2.8 ± 1.5 kg ha−1 VDD−1. We revealed a significant (p < 0.05 negative exponential relationship between γVDD and multi-year mean VDD for winter wheat across TE, with higher γVDD in winter wheat planting areas with lower multi-year mean VDD. Our findings shed light on potential vulnerability of winter wheat yields to warming-mediated vernalization variations over TE, particularly considering a likely future warmer climate.

Life on a warmer earth: possible climatic consequences of man-made global warming. [Monograph

Energy Technology Data Exchange (ETDEWEB)

1981-01-01

A summary of research conducted by the International Institute for Applied Systems Analysis (IIASA) and published by H. Flohn in 1977 updates the original data to March 1980. The work explores the interaction between energy and climate, including the impact on the global climate of three main energy sources: solar, nuclear, and fossil fuels. Its findings describe the global warming effects caused by carbon dioxide released by burning fossil fuels and by other trace gases released into the atmosphere. The approach is paleoclimatic in that it gains insights into what global warming will produce by considering what is known about past periods of the earth's history when the global average surface temperature was higher than it is now. Although paleoclimatic knowledge is limited, no complete model of the climatic system is available. This research uses both approaches, combining the two to some extent. 10 figures.

Assessing the effect of the relative atmospheric angular momentum (AAM) on length-of-day (LOD) variations under climate warming

Science.gov (United States)

Lehmann, E.; Hansen, F.; Ulbrich, U.; Nevir, P.; Leckebusch, G. C.

2009-04-01

While most studies on model-projected future climate warming discuss climatological quantities, this study investigates the response of the relative atmospheric angular momentum (AAM) to climate warming for the 21th century and discusses its possible effects on future length-of-day variations. Following the derivation of the dynamic relation between atmosphere and solid earth by Barnes et al. (Proc. Roy. Soc., 1985) this study relates the axial atmospheric excitation function X3 to changes in length-of-day that are proportional to variations in zonal winds. On interannual time scales changes in the relative AAM (ERA40 reanalyses) are well correlated with observed length-of-day (LOD, IERS EOP CO4) variability (r=0.75). The El Niño-Southern Oscillation (ENSO) is a prominent coupled ocean-atmosphere phenomenon to cause global climate variability on interannual time scales. Correspondingly, changes in observed LOD relate to ENSO due to observed strong wind anomalies. This study investigates the varying effect of AAM anomalies on observed LOD by relating AAM to variations to ENSO teleconnections (sea surface temperatures, SSTs) and the Pacific North America (PNA) oscillation for the 20th and 21st century. The differently strong effect of strong El Niño events (explained variance 71%-98%) on present time (1962-2000) observed LOD-AAM relation can be associated to variations in location and strength of jet streams in the upper troposphere. Correspondingly, the relation between AAM and SSTs in the NIÑO 3.4 region also varies between explained variances of 15% to 73%. Recent coupled ocean-atmosphere projections on future climate warming suggest changes in frequency and amplitude of ENSO events. Since changes in the relative AAM indicate shifts in large-scale atmospheric circulation patterns due to climate change, AAM - ENSO relations are assessed in coupled atmosphere-ocean (ECHAM5-OM1) climate warming projections (A1B) for the 21st century. A strong rise (+31%) in

Vulnerability of white spruce tree growth in interior Alaska in response to climate variability: dendrochronological, demographic, and experimental perspectives

Science.gov (United States)

A.D. McGuire; R.W. Ruess; A. Lloyd; J. Yarie; J.S. Clein; G.P. Juday

2010-01-01

This paper integrates dendrochronological, demographic, and experimental perspectives to improve understanding of the response of white spruce (Picea glauca (Moench) Voss) tree growth to climatic variability in interior Alaska. The dendrochronological analyses indicate that climate warming has led to widespread declines in white spruce growth...

ONERC Observatoire National sur les Effets du Rechauffement Climatique (National Observatory of Climate warming effects). Report to the Prime Minister and to Parliament. Climate changes and public health risks in France

International Nuclear Information System (INIS)

2010-01-01

After having recalled the climate change context and the activities of the ONERC (the French National Observatory of Climate Warming Effects) since its previous report, this report gathers several contributions by as many scientists. They propose analysis, comments and discussions on various topics: human diseases which might be influenced by climate change in France (heat waves and allergies, emergence of animal and human diseases, potential impacts of climate change on vector-borne diseases, infectious diseases in overseas territories, public health consequences), surveillance and health alert systems (infectious disease national surveillance and monitoring network, emergency response, satellite imagery, public health and risk management, lessons learned from the chikungunya pandemic), public health and risk management (overview of international works on the relationship between climate change and public health, public health consequences of climate change)

Climate change hotspots in the CMIP5 global climate model ensemble.

Science.gov (United States)

Diffenbaugh, Noah S; Giorgi, Filippo

2012-01-10

We use a statistical metric of multi-dimensional climate change to quantify the emergence of global climate change hotspots in the CMIP5 climate model ensemble. Our hotspot metric extends previous work through the inclusion of extreme seasonal temperature and precipitation, which exert critical influence on climate change impacts. The results identify areas of the Amazon, the Sahel and tropical West Africa, Indonesia, and the Tibetan Plateau as persistent regional climate change hotspots throughout the 21 st century of the RCP8.5 and RCP4.5 forcing pathways. In addition, areas of southern Africa, the Mediterranean, the Arctic, and Central America/western North America also emerge as prominent regional climate change hotspots in response to intermediate and high levels of forcing. Comparisons of different periods of the two forcing pathways suggest that the pattern of aggregate change is fairly robust to the level of global warming below approximately 2°C of global warming (relative to the late-20 th -century baseline), but not at the higher levels of global warming that occur in the late-21 st -century period of the RCP8.5 pathway, with areas of southern Africa, the Mediterranean, and the Arctic exhibiting particular intensification of relative aggregate climate change in response to high levels of forcing. Although specific impacts will clearly be shaped by the interaction of climate change with human and biological vulnerabilities, our identification of climate change hotspots can help to inform mitigation and adaptation decisions by quantifying the rate, magnitude and causes of the aggregate climate response in different parts of the world.

Paris Agreement climate proposals need a boost to keep warming well below 2 °c

NARCIS (Netherlands)

Rogelj, Joeri; Elzen, Den Michel; Höhne, Niklas; Fransen, Taryn; Fekete, Hanna; Winkler, Harald; Schaeffer, Roberto; Sha, Fu; Riahi, Keywan; Meinshausen, Malte

2016-01-01

The Paris climate agreement aims at holding global warming to well below 2 degrees Celsius and to "pursue efforts" to limit it to 1.5 degrees Celsius. To accomplish this, countries have submitted Intended Nationally Determined Contributions (INDCs) outlining their post-2020 climate action. Here

Climate change damage functions in LCA – (1) from global warming potential to natural environment damages

DEFF Research Database (Denmark)

Callesen, Ingeborg; Hauschild, Michael Zwicky; Bagger Jørgensen, Rikke

Energy use often is the most significant contributor to the impact category ‘global warming’ in life cycle impact assessment. However, the potential global warming effects on the climate at regional level and consequential effects on the natural environment are not thoroughly described within LCA...... methodology. The current scientific understanding of the extent of climate change impacts is limited due to the immense complexity of the multi-factorial environmental changes and unknown adaptive capacities at process, species and ecosystem level. In the presentation we argue that the global warming impacts...

Seasonal Climate Extremes : Mechanism, Predictability and Responses to Global Warming

NARCIS (Netherlands)

Shongwe, M.E.

2010-01-01

Climate extremes are rarely occurring natural phenomena in the climate system. They often pose one of the greatest environmental threats to human and natural systems. Statistical methods are commonly used to investigate characteristics of climate extremes. The fitted statistical properties are often

How warm days increase belief in global warming

Science.gov (United States)

Zaval, Lisa; Keenan, Elizabeth A.; Johnson, Eric J.; Weber, Elke U.

2014-02-01

Climate change judgements can depend on whether today seems warmer or colder than usual, termed the local warming effect. Although previous research has demonstrated that this effect occurs, studies have yet to explain why or how temperature abnormalities influence global warming attitudes. A better understanding of the underlying psychology of this effect can help explain the public's reaction to climate change and inform approaches used to communicate the phenomenon. Across five studies, we find evidence of attribute substitution, whereby individuals use less relevant but available information (for example, today's temperature) in place of more diagnostic but less accessible information (for example, global climate change patterns) when making judgements. Moreover, we rule out alternative hypotheses involving climate change labelling and lay mental models. Ultimately, we show that present temperature abnormalities are given undue weight and lead to an overestimation of the frequency of similar past events, thereby increasing belief in and concern for global warming.

Warm Rain Processes Over the Tropical Oceans and Implications on Climate Change: Results from TRMM and GOES GCM

Science.gov (United States)

Lau, William K. M.; Wu, H. T.

2004-01-01

In this talk, we will first show results from TRMM data regarding the characteristics of warm rains over the tropical oceans, and the dependence of rate of warm rain production on sea surface temperature. Results lead to the hypothesis that warm rain production efficiency, i.e., autoconversion, may be increased in a warm climate. We use the GEOS-II GCM to test this hypothesis. Our modeling results show that in a climate with increased rate of autoconversion, the total rain amount is increased, with warm rain contributing to a larger portion of the increase. The abundant rainout of warm precipitation causes a reduction of low and middle cloud amount due to rainout, and reduced high clouds due to less water vapor available for ice-phase convection. However, clod radiation feedback caused by the increased rainfall efficiency, leads to differential vertical heating/cooling producing a more unstable atmosphere, allowing, more intense, but isolated penetrative convection, with contracted anvils to develop. Results also show that increased autoconversion reduces the convective adjustment time scale, resulting in faster recycling of atmospheric water. Most interestingly, the increased low level heating associated with warm rain leads to more energetic Madden and Julian oscillations in the tropics, with well-defined eastward propagation. While reducing the autoconversion leads to an abundant mix of westward and eastward tropical disturbances on daily to weekly time scales. The crucial link of precipitation microphysical processes to climate change including the effects of aerosols will be discussed.

Warm Rain Processes over the Tropical Oceans and Implications on Climate Change: Results from TRMM and GEOS GCM

Science.gov (United States)

Lau, William K. M.; Wu, H. T.

2004-01-01

In this talk, we will first show results from TRMM data regarding the characteristics of warm rains over the tropical oceans, and the dependence of rate of warm rain production on sea surface temperature. Results lead to the hypothesis that warm rain production efficiency, i.e., autoconversion, may be increased in a warm climate. We use the GEOS-II GCM to test this hypothesis. Our modeling results show that in a climate with increased rate of autoconversion, the total rain amount is increased, with warm rain contributing to larger portion of the increase. The abundant rainout of warm precipitation causes a reduction of low and middle cloud amount due to rainout, and reduced high clouds due to less water vapor available for ice-phase convection. However, clod radiation feedback caused by the increased rainfall efficiency, leads to differential vertical heating/cooling producing a more unstable atmosphere, allowing, more intense, but isolated penetrative convection, with contracted anvils to develop. Results also show that increased autoconversion reduces the convective adjustment time scale, resulting in faster recycling of atmospheric water. Most interestingly, the increased low level heating associated with warm rain leads to more energetic Madden and Julian oscillations in the tropics, with well-defined eastward propagation. While reducing the autoconversion leads to an abundant mix of westward and eastward tropical disturbances on daily to weekly time scales. The crucial link of precipitation microphysical processes to climate change including the effects of aerosols will be discussed.

Medical Providers as Global Warming and Climate Change Health Educators: A Health Literacy Approach

Science.gov (United States)

Villagran, Melinda; Weathers, Melinda; Keefe, Brian; Sparks, Lisa

2010-01-01

Climate change is a threat to wildlife and the environment, but it also one of the most pervasive threats to human health. The goal of this study was to examine the relationships among dimensions of health literacy, patient education about global warming and climate change (GWCC), and health behaviors. Results reveal that patients who have higher…

Range shifts or extinction? Ancient DNA and distribution modelling reveal past and future responses to climate warming in cold-adapted birds.

Science.gov (United States)

Lagerholm, Vendela K; Sandoval-Castellanos, Edson; Vaniscotte, Amélie; Potapova, Olga R; Tomek, Teresa; Bochenski, Zbigniew M; Shepherd, Paul; Barton, Nick; Van Dyck, Marie-Claire; Miller, Rebecca; Höglund, Jacob; Yoccoz, Nigel G; Dalén, Love; Stewart, John R

2017-04-01

Global warming is predicted to cause substantial habitat rearrangements, with the most severe effects expected to occur in high-latitude biomes. However, one major uncertainty is whether species will be able to shift their ranges to keep pace with climate-driven environmental changes. Many recent studies on mammals have shown that past range contractions have been associated with local extinctions rather than survival by habitat tracking. Here, we have used an interdisciplinary approach that combines ancient DNA techniques, coalescent simulations and species distribution modelling, to investigate how two common cold-adapted bird species, willow and rock ptarmigan (Lagopus lagopus and Lagopus muta), respond to long-term climate warming. Contrary to previous findings in mammals, we demonstrate a genetic continuity in Europe over the last 20 millennia. Results from back-casted species distribution models suggest that this continuity may have been facilitated by uninterrupted habitat availability and potentially also the greater dispersal ability of birds. However, our predictions show that in the near future, some isolated regions will have little suitable habitat left, implying a future decrease in local populations at a scale unprecedented since the last glacial maximum. © 2016 John Wiley & Sons Ltd.

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

Fluvial response to abrupt global warming at the Palaeocene/Eocene boundary.

Science.gov (United States)

Foreman, Brady Z; Heller, Paul L; Clementz, Mark T

2012-11-01

Climate strongly affects the production of sediment from mountain catchments as well as its transport and deposition within adjacent sedimentary basins. However, identifying climatic influences on basin stratigraphy is complicated by nonlinearities, feedback loops, lag times, buffering and convergence among processes within the sediment routeing system. The Palaeocene/Eocene thermal maximum (PETM) arguably represents the most abrupt and dramatic instance of global warming in the Cenozoic era and has been proposed to be a geologic analogue for anthropogenic climate change. Here we evaluate the fluvial response in western Colorado to the PETM. Concomitant with the carbon isotope excursion marking the PETM we document a basin-wide shift to thick, multistoried, sheets of sandstone characterized by variable channel dimensions, dominance of upper flow regime sedimentary structures, and prevalent crevasse splay deposits. This progradation of coarse-grained lithofacies matches model predictions for rapid increases in sediment flux and discharge, instigated by regional vegetation overturn and enhanced monsoon precipitation. Yet the change in fluvial deposition persisted long after the approximately 200,000-year-long PETM with its increased carbon dioxide levels in the atmosphere, emphasizing the strong role the protracted transmission of catchment responses to distant depositional systems has in constructing large-scale basin stratigraphy. Our results, combined with evidence for increased dissolved loads and terrestrial clay export to world oceans, indicate that the transient hyper-greenhouse climate of the PETM may represent a major geomorphic 'system-clearing event', involving a global mobilization of dissolved and solid sediment loads on Earth's surface.

Response of salt-marsh carbon accumulation to climate change.

Science.gov (United States)

Kirwan, Matthew L; Mudd, Simon M

2012-09-27

About half of annual marine carbon burial takes place in shallow water ecosystems where geomorphic and ecological stability is driven by interactions between the flow of water, vegetation growth and sediment transport. Although the sensitivity of terrestrial and deep marine carbon pools to climate change has been studied for decades, there is little understanding of how coastal carbon accumulation rates will change and potentially feed back on climate. Here we develop a numerical model of salt marsh evolution, informed by recent measurements of productivity and decomposition, and demonstrate that competition between mineral sediment deposition and organic-matter accumulation determines the net impact of climate change on carbon accumulation in intertidal wetlands. We find that the direct impact of warming on soil carbon accumulation rates is more subtle than the impact of warming-driven sea level rise, although the impact of warming increases with increasing rates of sea level rise. Our simulations suggest that the net impact of climate change will be to increase carbon burial rates in the first half of the twenty-first century, but that carbon-climate feedbacks are likely to diminish over time.

Changes in the microbial community structure of bacteria, archaea and fungi in response to elevated CO(2) and warming in an Australian native grassland soil.

Science.gov (United States)

Hayden, Helen L; Mele, Pauline M; Bougoure, Damian S; Allan, Claire Y; Norng, Sorn; Piceno, Yvette M; Brodie, Eoin L; Desantis, Todd Z; Andersen, Gary L; Williams, Amity L; Hovenden, Mark J

2012-12-01

The microbial community structure of bacteria, archaea and fungi is described in an Australian native grassland soil after more than 5 years exposure to different atmospheric CO2 concentrations ([CO2]) (ambient, +550 ppm) and temperatures (ambient, + 2°C) under different plant functional types (C3 and C4 grasses) and at two soil depths (0-5 cm and 5-10 cm). Archaeal community diversity was influenced by elevated [CO2], while under warming archaeal 16S rRNA gene copy numbers increased for C4 plant Themeda triandra and decreased for the C3 plant community (P fungi in soil responded differently to elevated [CO2], warming and their interaction. Taxa identified as significantly climate-responsive could show differing trends in the direction of response ('+' or '-') under elevated CO2 or warming, which could then not be used to predict their interactive effects supporting the need to investigate interactive effects for climate change. The approach of focusing on specific taxonomic groups provides greater potential for understanding complex microbial community changes in ecosystems under climate change. © 2012 Society for Applied Microbiology and Blackwell Publishing Ltd.

Scenario dependence of future changes in climate extremes under 1.5 °C and 2 °C global warming

Science.gov (United States)

Wang, Zhili; Lin, Lei; Zhang, Xiaoye; Zhang, Hua; Liu, Liangke; Xu, Yangyang

2017-01-01

The 2015 Paris Agreement aims to limit global warming below 2 °C and pursue efforts to even limit it to 1.5 °C relative to pre-industrial levels. Decision makers need reliable information on the impacts caused by these warming levels for climate mitigation and adaptation measures. We explore the changes in climate extremes, which are closely tied to economic losses and casualties, under 1.5 °C and 2 °C global warming and their scenario dependence using three sets of ensemble global climate model simulations. A warming of 0.5 °C (from 1.5 °C to 2 °C) leads to significant increases in temperature and precipitation extremes in most regions. However, the projected changes in climate extremes under both warming levels highly depend on the pathways of emissions scenarios, with different greenhouse gas (GHG)/aerosol forcing ratio and GHG levels. Moreover, there are multifold differences in several heavily polluted regions, among the scenarios, in the changes in precipitation extremes due to an additional 0.5 °C warming from 1.5 °C to 2 °C. Our results demonstrate that the chemical compositions of emissions scenarios, not just the total radiative forcing and resultant warming level, must be considered when assessing the impacts of global 1.5/2 °C warming. PMID:28425445

Meta-analysis reveals complex marine biological responses to the interactive effects of ocean acidification and warming

Science.gov (United States)

Harvey, Ben P; Gwynn-Jones, Dylan; Moore, Pippa J

2013-01-01

Ocean acidification and warming are considered two of the greatest threats to marine biodiversity, yet the combined effect of these stressors on marine organisms remains largely unclear. Using a meta-analytical approach, we assessed the biological responses of marine organisms to the effects of ocean acidification and warming in isolation and combination. As expected biological responses varied across taxonomic groups, life-history stages, and trophic levels, but importantly, combining stressors generally exhibited a stronger biological (either positive or negative) effect. Using a subset of orthogonal studies, we show that four of five of the biological responses measured (calcification, photosynthesis, reproduction, and survival, but not growth) interacted synergistically when warming and acidification were combined. The observed synergisms between interacting stressors suggest that care must be made in making inferences from single-stressor studies. Our findings clearly have implications for the development of adaptive management strategies particularly given that the frequency of stressors interacting in marine systems will be likely to intensify in the future. There is now an urgent need to move toward more robust, holistic, and ecologically realistic climate change experiments that incorporate interactions. Without them accurate predictions about the likely deleterious impacts to marine biodiversity and ecosystem functioning over the next century will not be possible. PMID:23610641

Peatland Carbon Dynamics in Alaska During Past Warm Climates

Science.gov (United States)

Yu, Z.; Cleary, K.; Massa, C.; Hunt, S. J.; Klein, E. S.; Loisel, J.

2013-12-01

Peatlands represent a large belowground carbon (C) pool in the biosphere. However, how peatland C sequestration capacity varies with changes in climate and climate-induced disturbance is still poorly understood and debated. Here we summarize results from Alaskan peatlands to document how peat C accumulation has responded to past warm climate intervals. We find that the greatest C accumulation rates at sites from the Kenai Peninsula to the North Slope occurred during the Holocene thermal maximum (HTM) in the early Holocene. This time period also corresponds with explosive formation and expansion of new peatlands on the landscape across Alaska. In addition, we note that many peatlands that existed during the earlier Holocene on the North Slope have disappeared and are presently covered by mineral soils under tundra or sandy deposits. During the Medieval Climate Anomaly (MCA) around 1000-500 years ago, several peatlands in Alaska show high rates of C accumulation when compared to the period before the MCA during the Neoglacial or the following Little Ice Age period. Altogether, our results indicate that the Alaskan landscape was very different during the last 10,000 years and that peatlands can rapidly accumulate C under warm climatic conditions. We speculate that warmth-stimulated increase in plant production surpasses increase in peat decomposition during the early Holocene, and potentially also during the MCA. Other factors that might have contributed to rapid peat accumulation during the early Holocene include increased summer sunlight, lowered sea levels, and decreased sea-ice cover/duration. Summer insolation was ca. 8% higher than today during the early Holocene due to orbital variations, which likely promoted plant productivity by increasing growing seasons sunlight. Furthermore, lower sea levels and exposed shallow continental shelves in the Beaufort Sea (Arctic Ocean) would have made the present-day Arctic Coastal Plain more continental, with warmer summers

The relative role of dispersal and local interactions for alpine plant community diversity under simulated climate warming

Energy Technology Data Exchange (ETDEWEB)

Klanderud, K.; Totland, Oe. [Norwegian Univ. of Life Science, Dept. of Ecology and Natural Resource Management, Aas (Norway)

2007-08-15

Most studies on factors determining diversity are conducted in temperate or warm regions, whereas studies in climatically harsh and low productivity areas, such as alpine regions, are rare. We examined the relative roles of seed availability and different biotic and abiotic factors for the diversity of an alpine plant community in southern Norway. Furthermore, because climate warming is predicted to be an important driver of alpine species diversity, we assessed how the relative impacts of dispersal and local interactions on diversity might change under experimental warming (open top chambers, OTCs). Addition of seeds from 27 regional species increased community diversity. The establishment of the species was negatively related both to the diversity of the existing system and the cover of the abundant dwarf shrub Dryas octopetala. These results show that both species dispersal limitation and local biotic interactions are important factors for alpine plant community diversity. Despite relatively harsh environmental conditions and low productivity, competition from the resident vegetation appeared to have a greater role for species establishment and diversity than facilitation and experimental warming. Higher temperature appeared to increase the negative relationship between resident species diversity and species establishment. This may suggest that climate warming can increase the role of interspecific competition for alpine plant community structure, and thus alter the long-term effects of biotic interactions on diversity. (au)

Global warming without global mean precipitation increase?

Science.gov (United States)

Salzmann, Marc

2016-06-01

Global climate models simulate a robust increase of global mean precipitation of about 1.5 to 2% per kelvin surface warming in response to greenhouse gas (GHG) forcing. Here, it is shown that the sensitivity to aerosol cooling is robust as well, albeit roughly twice as large. This larger sensitivity is consistent with energy budget arguments. At the same time, it is still considerably lower than the 6.5 to 7% K(-1) decrease of the water vapor concentration with cooling from anthropogenic aerosol because the water vapor radiative feedback lowers the hydrological sensitivity to anthropogenic forcings. When GHG and aerosol forcings are combined, the climate models with a realistic 20th century warming indicate that the global mean precipitation increase due to GHG warming has, until recently, been completely masked by aerosol drying. This explains the apparent lack of sensitivity of the global mean precipitation to the net global warming recently found in observations. As the importance of GHG warming increases in the future, a clear signal will emerge.

Tropical Indian Ocean warming contributions to China winter climate trends since 1960

Science.gov (United States)

Wu, Qigang; Yao, Yonghong; Liu, Shizuo; Cao, DanDan; Cheng, Luyao; Hu, Haibo; Sun, Leng; Yao, Ying; Yang, Zhiqi; Gao, Xuxu; Schroeder, Steven R.

2018-01-01

This study investigates observed and modeled contributions of global sea surface temperature (SST) to China winter climate trends in 1960-2014, including increased precipitation, warming through about 1997, and cooling since then. Observations and Atmospheric Model Intercomparison Project (AMIP) simulations with prescribed historical SST and sea ice show that tropical Indian Ocean (TIO) warming and increasing rainfall causes diabatic heating that generates a tropospheric wave train with anticyclonic 500-hPa height anomaly centers in the TIO or equatorial western Pacific (TIWP) and northeastern Eurasia (EA) and a cyclonic anomaly over China, referred to as the TIWP-EA wave train. The cyclonic anomaly causes Indochina moisture convergence and southwesterly moist flow that enhances South China precipitation, while the northern anticyclone enhances cold surges, sometimes causing severe ice storms. AMIP simulations show a 1960-1997 China cooling trend by simulating increasing instead of decreasing Arctic 500-hPa heights that move the northern anticyclone into Siberia, but enlarge the cyclonic anomaly so it still simulates realistic China precipitation trend patterns. A separate idealized TIO SST warming simulation simulates the TIWP-EA feature more realistically with correct precipitation patterns and supports the TIWP-EA teleconnection as the primary mechanism for long-term increasing precipitation in South China since 1960. Coupled Model Intercomparison Project (CMIP) experiments simulate a reduced TIO SST warming trend and weak precipitation trends, so the TIWP-EA feature is absent and strong drying is simulated in South China for 1960-1997. These simulations highlight the need for accurately modeled SST to correctly attribute regional climate trends.

Impact of a global warming on biospheric sources of methane and its climatic consequences

Energy Technology Data Exchange (ETDEWEB)

Hameed, S; Cess, R D

1983-01-01

Most atmospheric methane originates by bacterial processes in anaerobic environments within the soil, which become more productive with increases in ambient temperature. A warming of the climate, due to increasing levels of industrial gases resulting from fossil fuel burning, is likely to increase methane concentrations within the atmosphere, possibly leading to further heating, since both methane and ozone (which is generated in the troposphere from reactions of methane) have greenhouse effects. Investigators explored this feedback mechanism using a coupled climate-chemical model of the troposphere, by calculating the impact of the predicted global warming due to increased emissions of carbon dioxide and other industrial gases on the biospheric sources of methane. Although they found this climate feedback to be, by itself, relatively minor, it can produce measurable increases in atmospheric CH/sub 4/ concentration, a quantity that should additionally increase as a consequence of increasing anthropogenic emissions of CO and CH/sub 4/.

Integrating geological archives and climate models for the mid-Pliocene warm period

Science.gov (United States)

Haywood, Alan M.; Dowsett, Harry J.; Dolan, Aisling M.

2016-01-01

The mid-Pliocene Warm Period (mPWP) offers an opportunity to understand a warmer-than-present world and assess the predictive ability of numerical climate models. Environmental reconstruction and climate modelling are crucial for understanding the mPWP, and the synergy of these two, often disparate, fields has proven essential in confirming features of the past and in turn building confidence in projections of the future. The continual development of methodologies to better facilitate environmental synthesis and data/model comparison is essential, with recent work demonstrating that time-specific (time-slice) syntheses represent the next logical step in exploring climate change during the mPWP and realizing its potential as a test bed for understanding future climate change. PMID:26879640

Climate warming and interannual variability of phytoplankton phenology in the Northern Red Sea

KAUST Repository

Gittings, John

2016-01-01

of phytoplankton biomass), we investigate the potential impacts of climate warming on phytoplankton abundance and phenology in the Northern Red Sea by exploring the mechanistic links with the regional physical environment. The results of the analysis reveal that