Water Isotope Proxy-Proxy and Proxy-Model Convergence for Late Pleistocene East Asian Monsoon Rainfall Reconstructions

Science.gov (United States)

Clemens, S. C.; Holbourn, A.; Kubota, Y.; Lee, K. E.; Liu, Z.; Chen, G.

2017-12-01

Confidence in reconstruction of East Asian paleomonsoon rainfall using precipitation isotope proxies is a matter of considerable debate, largely due to the lack of correlation between precipitation amount and isotopic composition in the present climate. We present four new, very highly resolved records spanning the past 300,000 years ( 200 year sample spacing) from IODP Site U1429 in the East China Sea. We demonstrate that all the orbital- and millennial-scale variance in the onshore Yangtze River Valley speleothem δ18O record1 is also embedded in the offshore Site U1429 seawater δ18O record (derived from the planktonic foraminifer Globigerinoides ruber and sea surface temperature reconstructions). Signal replication in these two independent terrestrial and marine archives, both controlled by the same monsoon system, uniquely identifies δ18O of precipitation as the primary driver of the precession-band variance in both records. This proxy-proxy convergence also eliminates a wide array of other drivers that have been called upon as potential contaminants to the precipitation δ18O signal recorded by these proxies. We compare East Asian precipitation isotope proxy records to precipitation amount from a CCSM3 transient climate model simulation of the past 300,000 years using realistic insolation, ice volume, greenhouse gasses, and sea level boundary conditions. This model-proxy comparison suggests that both Yangtze River Valley precipitation isotope proxies (seawater and speleothem δ18O) track changes in summer-monsoon rainfall amount at orbital time scales, as do precipitation isotope records from the Pearl River Valley2 (leaf wax δ2H) and Borneo3 (speleothem δ18O). Notably, these proxy records all have significantly different spectral structure indicating strongly regional rainfall patterns that are also consistent with model results. Transient, isotope-enabled model simulations will be necessary to more thoroughly evaluate these promising results, and to

How Hot was Africa during the Mid-Holocene? Reexamining Africa's Thermal History via integrated Climate and Proxy System Modeling

Science.gov (United States)

Dee, S.; Russell, J. M.; Morrill, C.

2017-12-01

Climate models predict Africa will warm by up to 5°C in the coming century. Reconstructions of African temperature since the Last Glacial Maximum (LGM) have made fundamental contributions to our understanding of past, present, and future climate and can help constrain predictions from general circulation models (GCMs). However, many of these reconstructions are based on proxies of lake temperature, so the confounding influences of lacustrine processes may complicate our interpretations of past changes in tropical climate. These proxy-specific uncertainties require robust methodology for data-model comparison. We develop a new proxy system model (PSM) for paleolimnology to facilitate data-model comparison and to fully characterize uncertainties in climate reconstructions. Output from GCMs are used to force the PSM to simulate lake temperature, hydrology, and associated proxy uncertainties. We compare reconstructed East African lake and air temperatures in individual records and in a stack of 9 lake records to those predicted by our PSM forced with Paleoclimate Model Intercomparison Project (PMIP3) simulations, focusing on the mid-Holocene (6 kyr BP). We additionally employ single-forcing transient climate simulations from TraCE (10 kyr to 4 kyr B.P. and historical), as well as 200-yr time slice simulations from CESM1.0 to run the lake PSM. We test the sensitivity of African climate change during the mid-Holocene to orbital, greenhouse gas, and ice-sheet forcing in single-forcing simulations, and investigate dynamical hypotheses for these changes. Reconstructions of tropical African temperature indicate 1-2ºC warming during the mid-Holocene relative to the present, similar to changes predicted in the coming decades. However, most climate models underestimate the warming observed in these paleoclimate data (Fig. 1, 6kyr B.P.). We investigate this discrepancy using the new lake PSM and climate model simulations, with attention to the (potentially non

Identification of climatic state with limited proxy data

Directory of Open Access Journals (Sweden)

J. D. Annan

2012-07-01

Full Text Available We investigate the identifiability of the climate by limited proxy data. We test a data assimilation approach through perfect model pseudoproxy experiments, using a simple likelihood-based weighting based on the particle filtering process. Our experimental set-up enables us to create a massive 10 000-member ensemble at modest computational cost, thus enabling us to generate statistically robust results. We find that the method works well when data are sparse and imprecise, but in this case the reconstruction has a rather low accuracy as indicated by residual RMS errors. Conversely, when data are relatively plentiful and accurate, the estimate tracks the target closely, at least when considering the hemispheric mean. However, in this case, our prior ensemble size of 10 000 appears to be inadequate to correctly represent the true posterior, and the regional performance is poor. Using correlations to assess performance gives a more encouraging picture, with significant correlations ranging from about 0.3 when data are sparse to values over 0.7 when data are plentiful, but the residual RMS errors are substantial in all cases. Our results imply that caution is required in interpreting climate reconstructions, especially when considering the regional scale, as skill on this basis is markedly lower than on the large scale of hemispheric mean temperature.

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

Directory of Open Access Journals (Sweden)

A. Hind

2012-08-01

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

Technical Note: Correcting for signal attenuation from noisy proxy data in climate reconstructions

KAUST Repository

Ammann, C. M.; Genton, M. G.; Li, B.

2010-01-01

regression parameter estimation can lead to substantial amplitude attenuation if the predictors carry significant amounts of noise. This issue is known as "Measurement Error" (Fuller, 1987; Carroll et al., 2006). Climate proxies derived from tree-rings, ice

Support for global climate reorganization during the ''Medieval Climate Anomaly''

Energy Technology Data Exchange (ETDEWEB)

Graham, N.E. [Hydrologic Research Center, San Diego, CA (United States); Scripps Institution of Oceanography, La Jolla, CA (United States); Ammann, C.M. [National Center for Atmospheric Research, Boulder, CO (United States); Fleitmann, D. [University of Bern, Institute of Geological Sciences, Bern (Switzerland); University of Bern, Oeschger Centre for Climatic Change Research, Bern (Switzerland); Cobb, K.M. [Georgia Institute of Technology, Atlanta, GA (United States); Luterbacher, J. [Justus-Liebig-University, Giessen (Germany)

2011-09-15

Widely distributed proxy records indicate that the Medieval Climate Anomaly (MCA; {proportional_to}900-1350 AD) was characterized by coherent shifts in large-scale Northern Hemisphere atmospheric circulation patterns. Although cooler sea surface temperatures in the central and eastern equatorial Pacific can explain some aspects of medieval circulation changes, they are not sufficient to account for other notable features, including widespread aridity through the Eurasian sub-tropics, stronger winter westerlies across the North Atlantic and Western Europe, and shifts in monsoon rainfall patterns across Africa and South Asia. We present results from a full-physics coupled climate model showing that a slight warming of the tropical Indian and western Pacific Oceans relative to the other tropical ocean basins can induce a broad range of the medieval circulation and climate changes indicated by proxy data, including many of those not explained by a cooler tropical Pacific alone. Important aspects of the results resemble those from previous simulations examining the climatic response to the rapid Indian Ocean warming during the late twentieth century, and to results from climate warming simulations - especially in indicating an expansion of the Northern Hemisphere Hadley circulation. Notably, the pattern of tropical Indo-Pacific sea surface temperature (SST) change responsible for producing the proxy-model similarity in our results agrees well with MCA-LIA SST differences obtained in a recent proxy-based climate field reconstruction. Though much remains unclear, our results indicate that the MCA was characterized by an enhanced zonal Indo-Pacific SST gradient with resulting changes in Northern Hemisphere tropical and extra-tropical circulation patterns and hydroclimate regimes, linkages that may explain the coherent regional climate shifts indicated by proxy records from across the planet. The findings provide new perspectives on the nature and possible causes of the MCA

Climate change scenarios and key climate indices in the Swiss Alpine region

Science.gov (United States)

Zubler, Elias; Croci-Maspoli, Mischa; Frei, Christoph; Liniger, Mark; Scherrer, Simon; Appenzeller, Christof

2013-04-01

For climate adaption and to support climate mitigation policy it is of outermost importance to demonstrate the consequences of climate change on a local level and in user oriented quantities. Here, a framework is presented to apply the Swiss national climate change scenarios CH2011 to climate indices with direct relevance to applications, such as tourism, transportation, agriculture and health. This framework provides results on a high spatial and temporal resolution and can also be applied in mountainous regions such as the Alps. Results are shown for some key indices, such as the number of summer days and tropical nights, growing season length, number of frost days, heating and cooling degree days, and the number of days with fresh snow. Particular focus is given to changes in the vertical distribution for the future periods 2020-2049, 2045-2074 and 2070-2099 relative to the reference period 1980-2009 for the A1B, A2 and RCP3PD scenario. The number of days with fresh snow is approximated using a combination of temperature and precipitation as proxies. Some findings for the latest scenario period are: (1) a doubling of the number of summer days by the end of the century under the business-as-usual scenario A2, (2) tropical nights appear above 1500 m asl, (3) the number of frost days may be reduced by more than 3 months at altitudes higher than 2500 m, (4) an overall reduction of heating degree days of about 30% by the end of the century, but on the other hand an increase in cooling degree days in warm seasons, and (5) the number of days with fresh snow tends to go towards zero at low altitudes. In winter, there is little change in snowfall above 2000 m asl (roughly -3 days) in all scenarios. The largest impact on snowfall is found along the Northern Alpine flank and the Jura (-10 days or roughly -50% in A1B for the winter season). It is also highlighted that the future projections for all indices strongly depend on the chosen scenario and on model uncertainty

Proxy comparisons for Paleogene sea water temperature reconstructions

Science.gov (United States)

de Bar, Marijke; de Nooijer, Lennart; Schouten, Stefan; Ziegler, Martin; Sluijs, Appy; Reichart, Gert-Jan

2017-04-01

, indicates that the fundamental mechanisms responsible for the proxy relation to temperature remained constant. de Bar, M. W., et al. (2016), Constraints on the application of long chain diol proxies in the Iberian Atlantic margin, Org. Geochem., 101, 184-195. Hollis, C. J., et al. (2012), Early Paleogene temperature history of the Southwest Pacific Ocean: Reconciling proxies and models, Earth Planet. Sci. Lett., 349, 53-66. Sluijs, A., et al. (2011), Southern ocean warming, sea level and hydrological change during the Paleocene-Eocene thermal maximum, Climate of the Past, 7(1), 47-61.

The Last Millennium Reanalysis: Improvements to proxies and proxy modeling

Science.gov (United States)

Tardif, R.; Hakim, G. J.; Emile-Geay, J.; Noone, D.; Anderson, D. M.

2017-12-01

The Last Millennium Reanalysis (LMR) employs a paleoclimate data assimilation (PDA) approach to produce climate field reconstructions (CFRs). Here, we focus on two key factors in PDA generated CFRs: the set of assimilated proxy records and forward models (FMs) used to estimate proxies from climate model output. In the initial configuration of the LMR [Hakim et al., 2016], the proxy dataset of [PAGES2k Consortium, 2013] was used, along with univariate linear FMs calibrated against annually-averaged 20th century temperature datasets. In an updated configuration, proxy records from the recent dataset [PAGES2k Consortium, 2017] are used, while a hierarchy of statistical FMs are tested: (1) univariate calibrated on annual temperature as in the initial configuration, (2) univariate against temperature as in (1) but calibration performed using expert-derived seasonality for individual proxy records, (3) as in (2) but expert proxy seasonality replaced by seasonal averaging determined objectively as part of the calibration process, (4) linear objective seasonal FMs as in (3) but objectively selecting relationships calibrated either on temperature or precipitation, and (5) bivariate linear models calibrated on temperature and precipitation with objectively-derived seasonality. (4) and (5) specifically aim at better representing the physical drivers of tree ring width proxies. Reconstructions generated using the CCSM4 Last Millennium simulation as an uninformed prior are evaluated against various 20th century data products. Results show the benefits of using the new proxy collection, particularly on the detrended global mean temperature and spatial patterns. The positive impact of using proper seasonality and temperature/moisture sensitivities for tree ring width records is also notable. This updated configuration will be used for the first generation of LMR-generated CFRs to be publicly released. These also provide a benchmark for future efforts aimed at evaluating the

Ecological response to climate change and human activities indicated by n-alkane proxy during the mid- to late Holocene: a case study from an alpine lake

Science.gov (United States)

Zhang, C.; Zhao, C.

2017-12-01

Paleolimonological records provide long-term dynamics information of past climate, environment, human activities and ecological variations and give evolutionary perspectives to understand responses process of ecological shift to internal or external trigger. In this study, a powerful biomarkers, n-alkanes, was used to reconstruct the past 5000 years organic matter sources and ecological evolution history of Beilianchi Lake in the southwestern of Loess Plateau after preliminary investigation of modern samples. Climate-environment change and human activities were also traced by total organic matter (TOC), magnetic susceptibility (MS) and relevant proxies. The results showed that the ecosystem related to organic matter composition in Beilianchi Lake might be mainly controlled by climate change before 1400 cal B.P., whereas after that, it was significantly influenced by soil erosion induced by increasing population and enhanced human activities. Lake ecosystem experienced periodical change from relatively stable stage with combination of allochthonous-autochthonous organic sources prior to 1400 cal B.P. to extremely instability and final return to steady state with allochthonous-dominant organic source since 300 cal B.P.. During the period of instability, organic matter composition during 1400-800 cal B.P. indicated a obvious bimodal distribution based on probability density distribution analysis, which reflected the lake ecosystem might stay at bistable state and switched repeatedly from more-macrophytes state (regime A with low ACL) towards less-macrophytes state (regime B with high ACL) controlled by disturbance of soil erosion. The flickering during this period could serve as the early warning signal of transition towards more-macrophytes state or less-macrophytes state in lake ecosystems.

Climate Proxies: An Inquiry-Based Approach to Discovering Climate Change on Antarctica

Science.gov (United States)

Wishart, D. N.

2016-12-01

An attractive way to advance climate literacy in higher education is to emphasize its relevance while teaching climate change across the curriculum to science majors and non-science majors. An inquiry-based pedagogical approach was used to engage five groups of students on a "Polar Discovery Project" aimed at interpreting the paleoclimate history of ice cores from Antarctica. Learning objectives and student learning outcomes were clearly defined. Students were assigned several exercises ranging from examination of Antarctic topography to the application of physical and chemical measurements as proxies for climate change. Required materials included base and topographic maps of Antarctica; graph sheets for construction of topographic cross-sectional profiles from profile lines of the Western Antarctica Ice Sheet (WAIS) Divide and East Antarctica; high-resolution photographs of Antarctic ice cores; stratigraphic columns of ice cores; borehole and glaciochemical data (i.e. anions, actions, δ18O, δD etc.); and isotope data on greenhouse gases (CH4, O2, N2) extracted from gas bubbles in ice cores. The methodology was to engage students in (2) construction of topographic profiles; (2) suggest directions for ice flow based on simple physics; (3) formulate decisions on suitable locations for drilling ice cores; (4) visual ice stratigraphy including ice layer counting; (5) observation of any insoluble particles (i.e. meteoritic and volcanic material); (6) analysis of borehole temperature profiles; and (7) the interpretation of several datasets to derive a paleoclimate history of these areas of the continent. The overall goal of the project was to improve the students analytical and quantitative skills; their ability to evaluate relationships between physical and chemical properties in ice cores, and to advance the understanding the impending consequences of climate change while engaging science, technology, engineering and mathematics (STEM). Student learning outcomes

Holocene climate changes in eastern Beringia (NW North America) – A systematic review of multi-proxy evidence

Science.gov (United States)

Kaufman, Darrell S.; Axford, Yarrow L.; Henderson, Andrew C.G.; McKay, Nicolas P.; Oswald, W. Wyatt; Saenger, Casey; Anderson, R. Scott; Bailey, Hannah L.; Clegg, Benjamin; Gajewski, Konrad; Hu, Feng Sheng; Jones, Miriam C.; Massa, Charly; Routson, Cody C.; Werner, Al; Wooller, Matthew J.; Yu, Zicheng

2016-01-01

Reconstructing climates of the past relies on a variety of evidence from a large number of sites to capture the varied features of climate and the spatial heterogeneity of climate change. This review summarizes available information from diverse Holocene paleoenvironmental records across eastern Beringia (Alaska, westernmost Canada and adjacent seas), and it quantifies the primary trends of temperature- and moisture-sensitive records based in part on midges, pollen, and biogeochemical indicators (compiled in the recently published Arctic Holocene database, and updated here to v2.1). The composite time series from these proxy records are compared with new summaries of mountain-glacier and lake-level fluctuations, terrestrial water-isotope records, sea-ice and sea-surface-temperature analyses, and peatland and thaw-lake initiation frequencies to clarify multi-centennial- to millennial-scale trends in Holocene climate change. To focus the synthesis, the paleo data are used to frame specific questions that can be addressed with simulations by Earth system models to investigate the causes and dynamics of past and future climate change. This systematic review shows that, during the early Holocene (11.7–8.2 ka; 1 ka = 1000 cal yr BP), rather than a prominent thermal maximum as suggested previously, temperatures were highly variable, at times both higher and lower than present (approximate mid-20th-century average), with no clear spatial pattern. Composited pollen, midge and other proxy records average out the variability and show the overall lowest summer and mean-annual temperatures across the study region during the earliest Holocene, followed by warming over the early Holocene. The sparse data available on early Holocene glaciation show that glaciers in southern Alaska were as extensive then as they were during the late Holocene. Early Holocene lake levels were low in interior Alaska, but moisture indicators show pronounced differences across the region. The highest

Model simulations and proxy-based reconstructions for the European region in the past millennium (Invited)

Science.gov (United States)

Zorita, E.

2009-12-01

One of the objectives when comparing simulations of past climates to proxy-based climate reconstructions is to asses the skill of climate models to simulate climate change. This comparison may accomplished at large spatial scales, for instance the evolution of simulated and reconstructed Northern Hemisphere annual temperature, or at regional or point scales. In both approaches a 'fair' comparison has to take into account different aspects that affect the inevitable uncertainties and biases in the simulations and in the reconstructions. These efforts face a trade-off: climate models are believed to be more skillful at large hemispheric scales, but climate reconstructions are these scales are burdened by the spatial distribution of available proxies and by methodological issues surrounding the statistical method used to translate the proxy information into large-spatial averages. Furthermore, the internal climatic noise at large hemispheric scales is low, so that the sampling uncertainty tends to be also low. On the other hand, the skill of climate models at regional scales is limited by the coarse spatial resolution, which hinders a faithful representation of aspects important for the regional climate. At small spatial scales, the reconstruction of past climate probably faces less methodological problems if information from different proxies is available. The internal climatic variability at regional scales is, however, high. In this contribution some examples of the different issues faced when comparing simulation and reconstructions at small spatial scales in the past millennium are discussed. These examples comprise reconstructions from dendrochronological data and from historical documentary data in Europe and climate simulations with global and regional models. These examples indicate that the centennial climate variations can offer a reasonable target to assess the skill of global climate models and of proxy-based reconstructions, even at small spatial scales

Linking coral river runoff proxies with climate variability, hydrology and land-use in Madagascar catchments.

Science.gov (United States)

Maina, Joseph; de Moel, Hans; Vermaat, Jan E; Bruggemann, J Henrich; Guillaume, Mireille M M; Grove, Craig A; Madin, Joshua S; Mertz-Kraus, Regina; Zinke, Jens

2012-10-01

Understanding the linkages between coastal watersheds and adjacent coral reefs is expected to lead to better coral reef conservation strategies. Our study aims to examine the main predictors of environmental proxies recorded in near shore corals and therefore how linked near shore reefs are to the catchment physical processes. To achieve these, we developed models to simulate hydrology of two watersheds in Madagascar. We examined relationships between environmental proxies derived from massive Porites spp. coral cores (spectral luminescence and barium/calcium ratios), and corresponding time-series (1950-2006) data of hydrology, climate, land use and human population growth. Results suggest regional differences in the main environmental drivers of reef sedimentation: on annual time-scales, precipitation, river flow and sediment load explained the variability in coral proxies of river discharge for the northeast region, while El Niño-Southern Oscillation (ENSO) and temperature (air and sea surface) were the best predictors in the southwest region. Copyright © 2012 Elsevier Ltd. All rights reserved.

Late Holocene monsoon climate as evidenced by proxy records from a lacustrine sediment sequence in western Guangdong, South China

Science.gov (United States)

Zhong, Wei; Cao, jiayuan; Xue, Jibin; Ouyang, Jun; Tang, Xiaohong; Yin, Huanling; Liao, Congyun; Long, Kun

2014-02-01

The study of a 300-cm-thick exposed lacustrine sediment section in the Hedong village in Zhaoqing area which is located in sub-tropical west Guangdong Province in South China, demonstrates that the lacustrine sedimentary sequence possibly contains evidence for exploring variation of Asian monsoon climate. Multi-proxy records, including the humification intensity, total organic carbon, and grain size fractions, reveal a general trend towards dry and cold conditions in the late Holocene that this is because of a decrease in solar insolation on an orbital scale. Three intensified Asian summer monsoon (ASM) intervals (˜3300-3000 cal yr BP, ˜2600-1600 cal yr BP, and ˜900-600 cal yr BP), and three weakened ASM intervals (˜4000-3300 cal yr BP, ˜3000-2600 cal yr BP, and ˜1600-900 cal yr BP) are identified. Our humification record (HDcal) shows a good correlation on multi-centennial scale with the tree ring Δ14C record, a proxy of solar activity. A spectral analysis of HDcal reveals four significant cycles, i.e., ˜1250 yr, 300 yr, 110 yr, and 70 yr, and most of these cycles are related to the solar activity. Our findings indicate that solar output and oceanic-atmospheric circulation probably have influenced the late Holocene climate variability in the study region.

Climate indices for vulnerability assessments

Energy Technology Data Exchange (ETDEWEB)

Persson, Gunn; Baerring, Lars; Kjellstroem, Erik; Strandberg, Gustav; Rummuk ainen, Markku

2007-08-15

The demand is growing for practical information on climate projections and the impacts expected in different geographical regions and different sectors. It is a challenge to transform the vast amount of data produced in climate models into relevant information for climate change impact studies. Climate indices based on climate model data can be used as means to communicate climate change impact relations. In this report a vast amount of results is presented from a multitude of indices based on different regional climate scenarios. The regional climate scenarios described in this report show many similarities with previous scenarios in terms of general evolution and amplitude of future European climate change. The broad features are manifested in increases in warm and decreases in cold indices. Likewise are presented increases in wet indices in the north and dry indices in the south. Despite the extensive nature of the material presented, it does not cover the full range of possible climate change. We foresee a continued interactive process with stakeholders as well as continued efforts and updates of the results presented in the report.

Climate Change Indicators

Science.gov (United States)

Presents information, charts and graphs showing measured climate changes across 40 indicators related to greenhouse gases, weather and climate, oceans, snow and ice, heath and society, and ecosystems.

Quercus macrocarpa annual, early- and latewood widths as hydroclimatic proxies, southeastern Saskatchewan, Canada

International Nuclear Information System (INIS)

Vanstone, Jessica R; Sauchyn, David J

2010-01-01

Fluctuations in size of annual ring-widths of Quercus species suggest that environmental factors influence the size and density of vessels within the ring, either by acting as a limiting factor for growth or through fine tuning of the wood structure to environmental factors. The purpose of this study is to assess the potential of Q. macrocarpa to provide multiple dendroclimatic proxies for the Canadian Prairies, by investigating growth responses of annual, early- and latewood widths to regional climate variability. Results indicate that ring width chronologies, from southeastern Saskatchewan capture regional signals related to moisture and drought conditions. Correlations suggest that late-wood widths are more representative of annual ring-widths, than are early-wood widths, and are the best proxy of seasonal fluctuations in climate. Thus regression models that include latewood widths were able to account for more variance in the Palmer Drought Severity Index (PDSI) than when annual ring-widths are used as the only proxy. This study demonstrates that Q. macrocarpa can provide multiple dendroclimatic proxies for investigating large scale climatic fluctuations at annual and sub-annual time scales. It is novel in terms of sub-annual analysis of tree-rings in a region that previously lacked dendrochronological research.

The use of Sphagnum cellulose oxygen isotope ratios in ombrotrophic peatlands as a proxy for paleoclimate.

Science.gov (United States)

Taylor, M.; Pendall, E.; Jackson, S.; Booth, R. K.; Nichols, J. E.; Huang, Y.

2006-12-01

Developing proxies for discerning paleoclimate that are independent of the pollen record can provide insight into various aspects of climate variability and improve confidence in the interpretation of climate-vegetation interactions. To date, proxies including plant macrofossils, humification indices, testate amoebae, and ratios of n-alkane abundances have been used to infer past climate variability from temperate ombrotrophic peatlands in upper Midwestern North America. These proxies are used to infer past changes in surface-moisture conditions, which in ombrotrophic peatlands is primarily a function of precipitation and temperature. This study investigates the potential uses of stable oxygen isotopes to complement hydrologic proxies. δ18O of surface water and Sphagnum moss cellulose from bogs throughout North America indicates a correlation between average growing season temperatures and δ18O-values. The existence of a modern temperature signal in moss cellulose suggests that δ18O-derived records will not only complement paleohydrological records, but also help assess relative changes in precipitation and temperature. Humification and testate amoebae data from two cores taken from Minden and Irwin Smith Bogs in central and northeastern Michigan have recorded several extreme drought events during the Holocene, including one at 1000 YBP. Comparison of δ18O-values of picked Sphagnum remains to down-core humification and testate amoebae data suggest good temporal correspondence, with the δ18O-values around 1000 YBP indicating a warmer growing season.

Latest Holocene Climate Variability revealed by a high-resolution multiple Proxy Record off Lisbon (Portugal)

Science.gov (United States)

Abrantes, F.; Lebreiro, S.; Ferreira, A.; Gil, I.; Jonsdottir, H.; Rodrigues, T.; Kissel, C.; Grimalt, J.

2003-04-01

The North Atlantic Oscillation (NAO) is known to have a major influence on the wintertime climate of the Atlantic basin and surrounding countries, determining precipitation and wind conditions at mid-latitudes. A comparison of Hurrel's NAO index to the mean winter (January-March) discharge of the Iberian Tagus River reveals a good negative correlation to negative NAO, while the years of largest upwelling anomalies, as referred in the literature, appear to be in good agreement with positive NAO. On this basis, a better understanding of the long-term variability of the NAO and Atlantic climate variability can be gained from high-resolution climate records from the Lisbon area. Climate variability of the last 2,000 years is assessed through a multiple proxy study of sedimentary sequences recovered from the Tagus prodelta deposition center, off Lisbon (Western Iberia). Physical properties, XRF and magnetic properties from core logging, grain size, δ18O, TOC, CaCO3, total alkenones, n-alkanes, alkenone SST, diatoms, benthic and planktonic foraminiferal assemblage compositions and fluxes are the proxies employed. The age model for site D13902 is based on AMS C-14 dates from mollusc and planktonic foraminifera shells, the reservoir correction for which was obtained by dating 3 pre-bomb, mollusc shells from the study area. Preliminary results indicate a Little Ice Age (LIA - 1300 - 1600 AD) alkenone derived SSTs around 15 degC followed by a sharp and rapid increase towards 19 degC. In spite the strong variability observed for most records, this low temperature interval is marked by a general increase in organic carbon, total alkenone concentration, diatom and foraminiferal abundances, as well as an increase in the sediment fine fraction and XRF determined Fe content, pointing to important river input and higher productivity. The Medieval Warm Period (1080 - 1300 AD) is characterized by 17-18 degC SSTs, increased mean grain size, but lower magnetic susceptibility and Fe

Using paleoclimate proxy-data to select optimal realisations in an ensemble of simulations of the climate of the past millennium

Energy Technology Data Exchange (ETDEWEB)

Goosse, Hugues [Universite Catholique de Louvain, Institut d' Astronomie et de Geophysique G. Lemaitre, Chemin du Cyclotron, 2, 1348, Louvain-la-Neuve (Belgium); Renssen, Hans [Vrije Universiteit Amsterdam, Faculty of Earth and Life Sciences, Amsterdam, HV (Netherlands); Timmermann, Axel [University of Hawaii, IPRC, SOEST, Honolulu, HI (United States); Bradley, Raymond S. [University of Massachusetts, Department of Geosciences, Masschusetts, MA (United States); Mann, Michael E. [Pennsylvania State University, Department of Meteorology and Earth and Environmental Systems Institute (EESI), Pennsylvania, PA (United States)

2006-08-15

We present and describe in detail the advantages and limitations of a technique that combines in an optimal way model results and proxy-data time series in order to obtain states of the climate system consistent with model physics, reconstruction of past radiative forcing and proxy records. To achieve this goal, we select among an ensemble of simulations covering the last millennium performed with a low-resolution 3-D climate model the ones that minimise a cost function. This cost function measures the misfit between model results and proxy records. In the framework of the tests performed here, an ensemble of 30 to 40 simulations appears sufficient to reach reasonable correlations between model results and reconstructions, in configurations for which a small amount of data is available as well as in data-rich areas. Preliminary applications of the technique show that it can be used to provide reconstructions of past large-scale temperature changes, complementary to the ones obtained by statistical methods. Furthermore, as model results include a representation of atmospheric and oceanic circulations, it can be used to provide insights into some amplification mechanisms responsible for past temperature changes. On the other hand, if the number of proxy records is too low, it could not be used to provide reconstructions of past changes at a regional scale. (orig.)

Hospital stay as a proxy indicator for severe injury in earthquakes: a retrospective analysis.

Science.gov (United States)

Zhao, Lu-Ping; Gerdin, Martin; Westman, Lina; Rodriguez-Llanes, Jose Manuel; Wu, Qi; van den Oever, Barbara; Pan, Liang; Albela, Manuel; Chen, Gao; Zhang, De-Sheng; Guha-Sapir, Debarati; von Schreeb, Johan

2013-01-01

Earthquakes are the most violent type of natural disasters and injuries are the dominant medical problem in the early phases after earthquakes. However, likely because of poor data availability, high-quality research on injuries after earthquakes is lacking. Length of hospital stay (LOS) has been validated as a proxy indicator for injury severity in high-income settings and could potentially be used in retrospective research of injuries after earthquakes. In this study, we assessed LOS as an adequate proxy indicator for severe injury in trauma survivors of an earthquake. A retrospective analysis was conducted using a database of 1,878 injured patients from the 2008 Wenchuan earthquake. Our primary outcome was severe injury, defined as a composite measure of serious injury or resource use. Secondary outcomes were serious injury and resource use, analysed separately. Non-parametric receiver operating characteristics (ROC) and area under the curve (AUC) analysis was used to test the discriminatory accuracy of LOS when used to identify severe injury. An 0.7earthquake survivors. However, LOS was found to be a proxy for major nonorthopaedic surgery and blood transfusion. These findings can be useful for retrospective research on earthquake-injured patients when detailed hospital records are not available.

Investigating Forest Inventory and Analysis-collected tree-ring data from Utah as a proxy for historical climate

Science.gov (United States)

R. Justin DeRose; W. Shih-Yu (Simon) Wang; John D. Shaw

2012-01-01

Increment cores collected as part of the periodic inventory in the Intermountain West were examined for their potential to represent growth and be a proxy for climate (precipitation) over a large region (Utah). Standardized and crossdated time-series created from pinyon pine (n=249) and Douglas-fir (n=274) increment cores displayed spatiotemporal patterns in growth...

A 481-year chronology of oak earlywood vessels as an age-independent climatic proxy in NW Iberia

Science.gov (United States)

Souto-Herrero, Manuel; Rozas, Vicente; García-González, Ignacio

2017-08-01

The earlywood vessels of ring-porous trees can be analyzed dendrochronologically and used as a proxy for environmental information. However, most works deal with the analysis of contemporary climate-growth relationships and do not evaluate their long-term variation. We obtained a 481-year chronology of earlywood vessel size of oak (Quercus robur L.) in the northwestern Iberian Peninsula, investigated its behavior through time, and compared it to a chronology of younger trees developed at the same site. We expressed earlywood vessel size as the hydraulically-weighted diameter (DH) and discriminated between vessels in the first row (r1) and the rest of the vessels (nr1); radial increment was assessed from latewood width (LW). Climate-growth relationships were strong and nearly identical for both age classes. Spring temperature positively affected vessel size, but only for the first row, probably mediating the onset of cambial activity. The chronology of old trees showed an almost flat age trend, except for the first decades, and series were not affected by stand dynamics. In contrast, LW had a weak response to climate, probably because of the high impact of abrupt growth changes. There was a high negative correlation between DH and the winter North Atlantic Oscillation Index (NAO), which was unstable during the 20th century. To our knowledge, this is the longest chronology of earlywood vessel size obtained to date, and offers promising results, as this proxy is shown to be independent of age and forest disturbances, and was strongly correlated to climate across long time spans.

Comparing proxy and model estimates of hydroclimate variability and change over the Common Era

Science.gov (United States)

Hydro2k Consortium, Pages

2017-12-01

Water availability is fundamental to societies and ecosystems, but our understanding of variations in hydroclimate (including extreme events, flooding, and decadal periods of drought) is limited because of a paucity of modern instrumental observations that are distributed unevenly across the globe and only span parts of the 20th and 21st centuries. Such data coverage is insufficient for characterizing hydroclimate and its associated dynamics because of its multidecadal to centennial variability and highly regionalized spatial signature. High-resolution (seasonal to decadal) hydroclimatic proxies that span all or parts of the Common Era (CE) and paleoclimate simulations from climate models are therefore important tools for augmenting our understanding of hydroclimate variability. In particular, the comparison of the two sources of information is critical for addressing the uncertainties and limitations of both while enriching each of their interpretations. We review the principal proxy data available for hydroclimatic reconstructions over the CE and highlight the contemporary understanding of how these proxies are interpreted as hydroclimate indicators. We also review the available last-millennium simulations from fully coupled climate models and discuss several outstanding challenges associated with simulating hydroclimate variability and change over the CE. A specific review of simulated hydroclimatic changes forced by volcanic events is provided, as is a discussion of expected improvements in estimated radiative forcings, models, and their implementation in the future. Our review of hydroclimatic proxies and last-millennium model simulations is used as the basis for articulating a variety of considerations and best practices for how to perform proxy-model comparisons of CE hydroclimate. This discussion provides a framework for how best to evaluate hydroclimate variability and its associated dynamics using these comparisons and how they can better inform

Molecular proxies for climate maladaptation in a long-lived tree (Pinus pinaster Aiton, Pinaceae).

Science.gov (United States)

Jaramillo-Correa, Juan-Pablo; Rodríguez-Quilón, Isabel; Grivet, Delphine; Lepoittevin, Camille; Sebastiani, Federico; Heuertz, Myriam; Garnier-Géré, Pauline H; Alía, Ricardo; Plomion, Christophe; Vendramin, Giovanni G; González-Martínez, Santiago C

2015-03-01

Understanding adaptive genetic responses to climate change is a main challenge for preserving biological diversity. Successful predictive models for climate-driven range shifts of species depend on the integration of information on adaptation, including that derived from genomic studies. Long-lived forest trees can experience substantial environmental change across generations, which results in a much more prominent adaptation lag than in annual species. Here, we show that candidate-gene SNPs (single nucleotide polymorphisms) can be used as predictors of maladaptation to climate in maritime pine (Pinus pinaster Aiton), an outcrossing long-lived keystone tree. A set of 18 SNPs potentially associated with climate, 5 of them involving amino acid-changing variants, were retained after performing logistic regression, latent factor mixed models, and Bayesian analyses of SNP-climate correlations. These relationships identified temperature as an important adaptive driver in maritime pine and highlighted that selective forces are operating differentially in geographically discrete gene pools. The frequency of the locally advantageous alleles at these selected loci was strongly correlated with survival in a common garden under extreme (hot and dry) climate conditions, which suggests that candidate-gene SNPs can be used to forecast the likely destiny of natural forest ecosystems under climate change scenarios. Differential levels of forest decline are anticipated for distinct maritime pine gene pools. Geographically defined molecular proxies for climate adaptation will thus critically enhance the predictive power of range-shift models and help establish mitigation measures for long-lived keystone forest trees in the face of impending climate change. Copyright © 2015 by the Genetics Society of America.

Indicators of climate impacts for forests: recommendations for the US National Climate Assessment indicators system

Science.gov (United States)

Linda S. Heath; Sarah M. Anderson; Marla R. Emery; Jeffrey A. Hicke; Jeremy Littell; Alan Lucier; Jeffrey G. Masek; David L. Peterson; Richard Pouyat; Kevin M. Potter; Guy Robertson; Jinelle Sperry; Andrzej Bytnerowicz; Sarah Jovan; Miranda H. Mockrin; Robert Musselman; Bethany K. Schulz; Robert J. Smith; Susan I. Stewart

2015-01-01

The Third National Climate Assessment (NCA) process for the United States focused in part on developing a system of indicators to communicate key aspects of the physical climate, climate impacts, vulnerabilities, and preparedness to inform decisionmakers and the public. Initially, 13 active teams were formed to recommend indicators in a range of categories, including...

The conceptualization and measurement of cognitive reserve using common proxy indicators: Testing some tenable reflective and formative models.

Science.gov (United States)

Ikanga, Jean; Hill, Elizabeth M; MacDonald, Douglas A

2017-02-01

The examination of cognitive reserve (CR) literature reveals a lack of consensus regarding conceptualization and pervasive problems with its measurement. This study aimed at examining the conceptual nature of CR through the analysis of reflective and formative models using eight proxies commonly employed in the CR literature. We hypothesized that all CR proxies would significantly contribute to a one-factor reflective model and that educational and occupational attainment would produce the strongest loadings on a single CR factor. The sample consisted of 149 participants (82 male/67 female), with 18.1 average years of education and ages of 45-99 years. Participants were assessed for eight proxies of CR (parent socioeconomic status, intellectual functioning, level of education, health literacy, occupational prestige, life leisure activities, physical activities, and spiritual and religious activities). Primary statistical analyses consisted of confirmatory factor analysis (CFA) to test reflective models and structural equation modeling (SEM) to evaluate multiple indicators multiple causes (MIMIC) models. CFA did not produce compelling support for a unitary CR construct when using all eight of our CR proxy variables in a reflective model but fairly cogent evidence for a one-factor model with four variable proxies. A second three-factor reflective model based upon an exploratory principal components analysis of the eight proxies was tested using CFA. Though all eight indicators significantly loaded on their assigned factors, evidence in support of overall model fit was mixed. Based upon the results involving the three-factor reflective model, two alternative formative models were developed and evaluated. While some support was obtained for both, the model in which the formative influences were specified as latent variables appeared to best account for the contributions of all eight proxies to the CR construct. While the findings provide partial support for our

Reconstructing Tropical Southwest Pacific Climate Variability and Mean State Changes at Vanuatu during the Medieval Climate Anomaly using Geochemical Proxies from Corals

Science.gov (United States)

Lawman, A. E.; Quinn, T. M.; Partin, J. W.; Taylor, F. W.; Thirumalai, K.; WU, C. C.; Shen, C. C.

2017-12-01

The Medieval Climate Anomaly (MCA: 950-1250 CE) is identified as a period during the last 2 millennia with Northern Hemisphere surface temperatures similar to the present. However, our understanding of tropical climate variability during the MCA is poorly constrained due to a lack of sub-annually resolved proxy records. We investigate seasonal and interannual variability during the MCA using geochemical records developed from two well preserved Porites lutea fossilized corals from the tropical southwest Pacific (Tasmaloum, Vanuatu; 15.6°S, 166.9°E). Absolute U/Th dates of 1127.1 ± 2.7 CE and 1105.1 ± 3.0 CE indicate that the selected fossil corals lived during the MCA. We use paired coral Sr/Ca and δ18O measurements to reconstruct sea surface temperature (SST) and the δ18O of seawater (a proxy for salinity). To provide context for the fossil coral records and test whether the mean state and climate variability at Vanuatu during the MCA is similar to the modern climate, our analysis also incorporates two modern coral records from Sabine Bank (15.9°S, 166.0°E) and Malo Channel (15.7°S, 167.2°E), Vanuatu for comparison. We quantify the uncertainty in our modern and fossil coral SST estimates via replication with multiple, overlapping coral records. Both the modern and fossil corals reproduce their respective mean SST value over their common period of overlap, which is 25 years in both cases. Based on over 100 years of monthly Sr/Ca data from each time period, we find that SSTs at Vanuatu during the MCA are 1.3 ± 0.7°C cooler relative to the modern. We also find that the median amplitude of the annual cycle is 0.8 ± 0.3°C larger during the MCA relative to the modern. Multiple data analysis techniques, including the standard deviation and the difference between the 95th and 5th percentiles of the annual SST cycle estimates, also show that the MCA has greater annual SST variability relative to the modern. Stable isotope data acquisition is ongoing, and when

Foraminifera Models to Interrogate Ostensible Proxy-Model Discrepancies During Late Pliocene

Science.gov (United States)

Jacobs, P.; Dowsett, H. J.; de Mutsert, K.

2017-12-01

Planktic foraminifera faunal assemblages have been used in the reconstruction of past oceanic states (e.g. the Last Glacial Maximum, the mid-Piacenzian Warm Period). However these reconstruction efforts have typically relied on inverse modeling using transfer functions or the modern analog technique, which by design seek to translate foraminifera into one or two target oceanic variables, primarily sea surface temperature (SST). These reconstructed SST data have then been used to test the performance of climate models, and discrepancies have been attributed to shortcomings in climate model processes and/or boundary conditions. More recently forward proxy models or proxy system models have been used to leverage the multivariate nature of proxy relationships to their environment, and to "bring models into proxy space". Here we construct ecological models of key planktic foraminifera taxa, calibrated and validated with World Ocean Atlas (WO13) oceanographic data. Multiple modeling methods (e.g. multilayer perceptron neural networks, Mahalanobis distance, logistic regression, and maximum entropy) are investigated to ensure robust results. The resulting models are then driven by a Late Pliocene climate model simulation with biogeochemical as well as temperature variables. Similarities and differences with previous model-proxy comparisons (e.g. PlioMIP) are discussed.

Incorporating Fundamentals of Climate Monitoring into Climate Indicators at the National Climatic Data Center

Science.gov (United States)

Arndt, D. S.

2014-12-01

In recent years, much attention has been dedicated to the development, testing and implementation of climate indicators. Several Federal agencies and academic groups have commissioned suites of indicators drawing upon and aggregating information available across the spectrum of climate data stewards and providers. As a long-time participant in the applied climatology discipline, NOAA's National Climatic Data Center (NCDC) has generated climate indicators for several decades. Traditionally, these indicators were developed for sectors with long-standing relationships with, and needs of, the applied climatology field. These have recently been adopted and adapted to meet the needs of sectors who have newfound sensitivities to climate and needs for climate data. Information and indices from NOAA's National Climatic Data Center have been prominent components of these indicator suites, and in some cases have been drafted in toto by these aggregators, often with improvements to the communicability and aesthetics of the indicators themselves. Across this history of supporting needs for indicators, NCDC climatologists developed a handful of practical approaches and philosophies that inform a successful climate monitoring product. This manuscript and presentation will demonstrate the utility this set of practical applications that translate raw data into useful information.

A multi-proxy reconstruction of Holocene climate change from Blessberg Cave, Germany

Science.gov (United States)

Breitenbach, Sebastian F. M.; Plessen, Birgit; Wenz, Sarah; Leonhardt, Jens; Tjallingii, Rik; Scholz, Denis; Jochum, Klaus Peter; Marwan, Norbert

2016-04-01

Although Holocene climate dynamics were relatively stable compared to glacial conditions, climatic changes had significant impact on ecosystems and human society on various timescales (Mayewski et al. 2004, Donges et al. 2015, Tan et al. 2015). Precious few high-resolution records on Holocene temperature and precipitation conditions in Central Europe are available (e.g., von Grafenstein et al. 1999, Fohlmeister et al. 2012). Here we present a speleothem-based reconstruction of past climate dynamics from Blessberg Cave, Thuringia, central Germany. Three calcitic stalagmites were recovered when the cave was discovered during tunneling operations in 2008. Samples BB-1, -2 and -3 were precisely dated by the 230Th/U-method, with errors between 10 and 160 years (2σ). The combined record covers large parts of the Holocene (10 - 0.4 ka BP). δ13C and δ18O were analysed at 100 μm resolution. To gain additional insights in infiltration conditions, Sr/Ca and S/Ca were measured on BB-1 and BB-3 using an Röntgenanalytik Eagle XXL μXRF scanner. Differences to other central European records (e.g., von Grafenstein et al. 1999, Fohlmeister et al. 2012) suggest complex interaction between multiple factors influencing speleothem δ18O in Blessberg Cave. Furthermore, no clear influence of the North Atlantic Oscillation on our proxies is found. However, a link across the N Atlantic realm is indicated by a centennial-scale correlation between Blessberg δ18O values and minerogenic input into lake SS1220 in Greenland over the last 5 ka (Olsen et al. 2012). In addition, recurrence analysis indicates an imprint of Atlantic Bond events on Blessberg δ18O values (Marwan et al. 2014), corroborating the suggested link with high northern latitudes. Larger runoff into the Greenland lake seems to be associated with lower δ18O, higher δ13C and S/Ca ratios, as well as lower Sr/Ca ratios in Blessberg Cave speleothems. This might be linked to lower local temperature and/or changes in

Detrital phosphorus as a proxy of flooding events in the Changjiang River Basin

International Nuclear Information System (INIS)

Meng, Jia; Yao, Peng; Bianchi, Thomas S.; Li, Dong; Zhao, Bin; Xu, Bochao; Yu, Zhigang

2015-01-01

In this study, sediment grain size (MGS), specific surface area (SSA), total organic carbon (TOC) contents, C/N molar ratios, stable carbon isotope, and P species in a sediment core, collected from the East China Sea (ECS) inner-shelf were measured to explore the applicability of detrital phosphorus (De-P) as a potential indicator of past flooding events in the Changjiang River Basin (CRB). In particular, we examined the linkages between the evolution of floods with regional climate changes and anthropogenic activities in the CRB. Peaks of De-P concentrations in sediments corresponded well with the worst flooding events of the CRB over the past two centuries (e.g., 1850s, 1860s, 1900s, 1920s, 1950s, 1980s, and 2000s). Moreover, De-P also corresponded well with the extreme hypoxic events in 1981 and 1998 in the Changjiang Estuary as indicated by Mo/Al ratios, indicating potential linkages between De-P as a flooding proxy to flood-induced hypoxia events in this region. In addition, a robust relationship was found among De-P, the floods in 1950s, 1980s, and 2000s of the CRB, the intensive El Niño-Southern Oscillation (ENSO), the abnormally weak East Asian Summer Monsoon (EASM) and the warm phase of Pacific Decadal Oscillation (PDO), suggesting that De-P also provided insights to linkages between regional climate change and flooding events in this region. - Highlights: • De-P was used to track past floods in the Changjiang River Basin (CRB). • De-P may serve as a proxy for flood-induced hypoxia events in the Changjiang Estuary. • De-P may be a proxy for examining linkages between floods and climatic drivers

Detrital phosphorus as a proxy of flooding events in the Changjiang River Basin

Energy Technology Data Exchange (ETDEWEB)

Meng, Jia [Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Qingdao 266100 (China); College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100 (China); Yao, Peng, E-mail: yaopeng@mail.ouc.edu.cn [Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Qingdao 266100 (China); Qingdao Collaborative Innovation Center of Marine Science and Technology, Qingdao 266100 (China); Institute of Marine Organic Geochemistry, Ocean University of China, Qingdao 266100 (China); Bianchi, Thomas S. [Department of Geological Sciences, University of Florida, Gainesville, FL 32611-2120 (United States); Li, Dong; Zhao, Bin; Xu, Bochao [Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Qingdao 266100 (China); College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100 (China); Yu, Zhigang [Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Qingdao 266100 (China); Institute of Marine Organic Geochemistry, Ocean University of China, Qingdao 266100 (China)

2015-06-01

In this study, sediment grain size (MGS), specific surface area (SSA), total organic carbon (TOC) contents, C/N molar ratios, stable carbon isotope, and P species in a sediment core, collected from the East China Sea (ECS) inner-shelf were measured to explore the applicability of detrital phosphorus (De-P) as a potential indicator of past flooding events in the Changjiang River Basin (CRB). In particular, we examined the linkages between the evolution of floods with regional climate changes and anthropogenic activities in the CRB. Peaks of De-P concentrations in sediments corresponded well with the worst flooding events of the CRB over the past two centuries (e.g., 1850s, 1860s, 1900s, 1920s, 1950s, 1980s, and 2000s). Moreover, De-P also corresponded well with the extreme hypoxic events in 1981 and 1998 in the Changjiang Estuary as indicated by Mo/Al ratios, indicating potential linkages between De-P as a flooding proxy to flood-induced hypoxia events in this region. In addition, a robust relationship was found among De-P, the floods in 1950s, 1980s, and 2000s of the CRB, the intensive El Niño-Southern Oscillation (ENSO), the abnormally weak East Asian Summer Monsoon (EASM) and the warm phase of Pacific Decadal Oscillation (PDO), suggesting that De-P also provided insights to linkages between regional climate change and flooding events in this region. - Highlights: • De-P was used to track past floods in the Changjiang River Basin (CRB). • De-P may serve as a proxy for flood-induced hypoxia events in the Changjiang Estuary. • De-P may be a proxy for examining linkages between floods and climatic drivers.

Mid- to Late Holocene climate development in Central Asia as revealed from multi-proxy analyses of sediments from Lake Son Kol (Kyrgyzstan)

Science.gov (United States)

Lauterbach, Stefan; Dulski, Peter; Gleixner, Gerd; Hettler-Riedel, Sabine; Mingram, Jens; Plessen, Birgit; Prasad, Sushma; Schwalb, Antje; Schwarz, Anja; Stebich, Martina; Witt, Roman

2013-04-01

A mid-Holocene shift from predominantly wet to significantly drier climate conditions, attributed to the weakening of the Asian summer monsoon (ASM), is documented in numerous palaeoclimate records from the monsoon-influenced parts of Asia, e.g. the Tibetan Plateau and north- and southeastern China. In contrast, Holocene climate development in the arid regions of mid-latitude Central Asia, located north and northwest of the Tibetan Plateau, is less well-constrained but supposed to have been influenced by a complex interaction between the mid-latitude Westerlies and the ASM. Hence, well-dated and highly resolved palaeoclimate records from Central Asia might provide important information about spatio-temporal changes in the regional interplay between Westerlies and ASM and thus aid the understanding of global climate teleconnections. As a part of the project CADY (Central Asian Climate Dynamics), aiming at reconstructing past climatic and hydrological variability in Central Asia, several sediment cores were recovered from alpine Lake Son Kol (41° 48'N, 75° 12'E, 3016 m a. s. l.) in the Central Tian Shan of Kyrgyzstan. A radiocarbon-dated sediment sequence of 154.5 cm length, covering approximately the last 6000 years, was investigated by using a multi-proxy approach, including sedimentological, (bio)geochemical, isotopic and micropalaeontological analyses. Preliminary proxy data indicate hydrologically variable but predominantly wet conditions until ca. 5100 cal. a BP, characterized by the deposition of finely laminated organic-carbonatic sediments. In contrast to monsoonal Asia, where a distinct trend towards drier conditions is observed since the mid-Holocene, the hydrologically variable interval at Lake Son Kol was apparently followed by an only short-term dry episode between ca. 5100 and 4200 cal. a BP. This is characterized by a higher δD of the C29 n-alkanes, probably reflecting increased evapotranspiration. Also pollen, diatom and ostracod data point

Carbohydrates and phenols as quantitative molecular vegetation proxies in peats

Science.gov (United States)

Kaiser, K.; Benner, R. H.

2012-12-01

Vegetation in peatlands is intricately linked to local environmental conditions and climate. Here we use chemical analyses of carbohydrates and phenols to reconstruct paleovegetation in peat cores collected from 56.8°N (SIB04), 58.4°N (SIB06), 63.8°N (G137) and 66.5°N (E113) in the Western Siberian Lowland. Lignin phenols (vanillyl and syringyl phenols) were sensitive biomarkers for vascular plant contributions and provided additional information on the relative contributions of angiosperm and gymnosperm plants. Specific neutral sugar compositions allowed identification of sphagnum mosses, sedges (Cyperaceae) and lichens. Hydroxyphenols released by CuO oxidation were useful tracers of sphagnum moss contributions. The three independent molecular proxies were calibrated with a diverse group of peat-forming plants to yield quantitative estimates (%C) of vascular plant, sphagnum moss and lichen contributions in peat core samples. Correlation analysis indicated the three molecular proxies produced fairly similar results for paleovegetation compositions, generally within the error interval of each approach (≤26%). The lignin-based method generally lead to higher estimates of vascular plant vegetation. Several significant deviations were also observed due to different reactivities of carbohydrate and phenolic polymers during peat decomposition. Rapid vegetation changes on timescales of 50-200 years were observed in the southern cores SIB04 and SIB06 over the last 2000 years. Vanillyl and syringyl phenol ratios indicated these vegetation changes were largely due to varying inputs of angiosperm and gymnosperm plants. The northern permafrost cores G137 and E113 showed a more stable development. Lichens briefly replaced sphagnum mosses and vascular plants in both of these cores. Shifts in vegetation did not correlate well with Northern hemisphere climate variability over the last 2000 years. This suggested that direct climate forcing of peatland dynamics was overridden

Comparison of Flood Vulnerability Assessments to Climate Change by Construction Frameworks for a Composite Indicator

Directory of Open Access Journals (Sweden)

Jong Seok Lee

2018-03-01

Full Text Available As extreme weather conditions due to climate change can cause deadly flood damages all around the world, a role of the flood vulnerability assessment has become recognized as one of the preemptive measures in nonstructural flood mitigation strategies. Although the flood vulnerability is most commonly assessed by a composite indicator compiled from multidimensional phenomena and multiple conflicting criteria associated with floods, directly or indirectly, it has been often overlooked that the construction frameworks and processes can have a significant influence on the flood vulnerability indicator outcomes. This study has, therefore, compared the flood vulnerability ranking orders for the 54 administrative districts in the Nakdong River Watershed of the Korean Peninsula, ranked from composite indicators by different frameworks and multi-attribute utility functions for combining the three assessment components, such as exposure, sensitivity, and coping, presented in the IPCC Third Assessment Report. The results show that the different aggregation components and utility functions under the same proxy variable system can lead to larger volatility of flood vulnerability rankings than expected. It is concluded that the vulnerability indicator needs to be derived from all three assessment components by a multiplicative utility function for a desirable flood vulnerability assessment to climate change.

Comparing Apples to Apples: Paleoclimate Model-Data comparison via Proxy System Modeling

Science.gov (United States)

Dee, Sylvia; Emile-Geay, Julien; Evans, Michael; Noone, David

2014-05-01

The wealth of paleodata spanning the last millennium (hereinafter LM) provides an invaluable testbed for CMIP5-class GCMs. However, comparing GCM output to paleodata is non-trivial. High-resolution paleoclimate proxies generally contain a multivariate and non-linear response to regional climate forcing. Disentangling the multivariate environmental influences on proxies like corals, speleothems, and trees can be complex due to spatiotemporal climate variability, non-stationarity, and threshold dependence. Given these and other complications, many paleodata-GCM comparisons take a leap of faith, relating climate fields (e.g. precipitation, temperature) to geochemical signals in proxy data (e.g. δ18O in coral aragonite or ice cores) (e.g. Braconnot et al., 2012). Isotope-enabled GCMs are a step in the right direction, with water isotopes providing a connector point between GCMs and paleodata. However, such studies are still rare, and isotope fields are not archived as part of LM PMIP3 simulations. More importantly, much of the complexity in how proxy systems record and transduce environmental signals remains unaccounted for. In this study we use proxy system models (PSMs, Evans et al., 2013) to bridge this conceptual gap. A PSM mathematically encodes the mechanistic understanding of the physical, geochemical and, sometimes biological influences on each proxy. To translate GCM output to proxy space, we have synthesized a comprehensive, consistently formatted package of published PSMs, including δ18O in corals, tree ring cellulose, speleothems, and ice cores. Each PSM is comprised of three sub-models: sensor, archive, and observation. For the first time, these different components are coupled together for four major proxy types, allowing uncertainties due to both dating and signal interpretation to be treated within a self-consistent framework. The output of this process is an ensemble of many (say N = 1,000) realizations of the proxy network, all equally plausible

Evidence of late Quaternary wet/dry climate episodes derived from paleoclimatic proxy data recovered from the paleoenvironmental record of the Great Basin of western North America: Paleobotanical studies

International Nuclear Information System (INIS)

1998-01-01

Through the integration of several avenues of paleoclimatic proxy data, the authors intend to arrive a definite conclusions regarding the frequency of periods of wetter climate, and to drive information regarding the magnitudes of these episodes, rates of their onset and demise, and the climatic conditions under which wetter climate can occur. These will in turn lead to rough estimates of: (1) the amounts of rainfall available for recharge during past periods of effectively wetter climate; and (2) the durations and spacing of such events that provide an indication of the amount of time that the area was subjected to these inputs. To accomplish these goals the paleobotanical record over a broad region is being examined to identify periods of greater effective precipitation. Although the project focus is on a region a of about 200 km around Yucca Mountain, they have collected data in other areas of the Great Basin in order to be able to identify large-scale climatic patterns. Once identified and described these climatic patterns can be separated from purely local climatic phenomena that might hinder the understanding of the Pliestocene climates of southern Nevada and the Yucca Mountain area in particular

Climate Proxy Signals in the Plio-Pleistocene Chemeron and Miocene Lukeino Formations, Baringo Basin, Kenya

Science.gov (United States)

Deino, A. L.; Kingston, J.; Hill, A.; Wilson, K. E.; Edgar, R.; Goble, E.

2009-12-01

The Chemeron Formation is a hominin-bearing, highly fossiliferous sequence of dominantly alluvial fan and fluvial sedimentary rocks, with climatically significant lacustrine intercalations, exposed within the Tugen Hills of the central Kenya Rift. As we have previously documented (Deino et al., 2006; Kingston et al., 2007), the formation contains a sequence of five 3-7 m thick diatomites in the interval 2.7-2.5 Ma that record, at precessional intervals, the repeated occurrence of deep-lake conditions in the Baringo Basin. These lakes appear abruptly, persist for only about 8,000 years of the ~23,000 year precessional cycle, and recede quickly. The oscillations have been tied to marine core and Mediterranean sapropel sections based on high-precision 40Ar/39Ar dating of K-feldspar in tuffs interspersed through the sequence, and paleomagnetic reversal stratigraphy. Ongoing paleontological investigations in the Tugen Hills are addressing the dynamics of high-resolution faunal and ecological change directly related to the fluctuating climatic background, including its effect on hominin evolution. This specific interval in the Baringo Basin/Tugen Hills has been identified by the Hominid Sites and Paleolakes Drilling Project Steering Committee as one of five target areas in East Africa for high-resolution coring studies. The drilling project is currently moving forward to the funding agency proposal development phase. Further exploration in the Tugen Hills has revealed a similar, older sequence of rhythmic alternating diatomites and non-lacustrine sediments in nearby drainages. These beds may represent a precessionally driven climate response possibly associated with the next older orbital eccentricity maximum from ~3.2-2.9 Ma. Characterization of the lithostratigraphy of this area is in progress, and samples of intercalated tuff beds suitable for high-precision single-crystal 40Ar/39Ar dating have been acquired. We have also extended our search for climate proxy records

Climate and landscape influence on indicators of lake carbon cycling through spatial patterns in dissolved organic carbon.

Science.gov (United States)

Lapierre, Jean-Francois; Seekell, David A; Del Giorgio, Paul A

2015-12-01

Freshwater ecosystems are strongly influenced by both climate and the surrounding landscape, yet the specific pathways connecting climatic and landscape drivers to the functioning of lake ecosystems are poorly understood. Here, we hypothesize that the links that exist between spatial patterns in climate and landscape properties and the spatial variation in lake carbon (C) cycling at regional scales are at least partly mediated by the movement of terrestrial dissolved organic carbon (DOC) in the aquatic component of the landscape. We assembled a set of indicators of lake C cycling (bacterial respiration and production, chlorophyll a, production to respiration ratio, and partial pressure of CO2 ), DOC concentration and composition, and landscape and climate characteristics for 239 temperate and boreal lakes spanning large environmental and geographic gradients across seven regions. There were various degrees of spatial structure in climate and landscape features that were coherent with the regionally structured patterns observed in lake DOC and indicators of C cycling. These different regions aligned well, albeit nonlinearly along a mean annual temperature gradient; whereas there was a considerable statistical effect of climate and landscape properties on lake C cycling, the direct effect was small and the overall effect was almost entirely overlapping with that of DOC concentration and composition. Our results suggest that key climatic and landscape signals are conveyed to lakes in part via the movement of terrestrial DOC to lakes and that DOC acts both as a driver of lake C cycling and as a proxy for other external signals. © 2015 John Wiley & Sons Ltd.

Detecting instabilities in tree-ring proxy calibration

Directory of Open Access Journals (Sweden)

H. Visser

2010-06-01

Full Text Available Evidence has been found for reduced sensitivity of tree growth to temperature in a number of forests at high northern latitudes and alpine locations. Furthermore, at some of these sites, emergent subpopulations of trees show negative growth trends with rising temperature. These findings are typically referred to as the "Divergence Problem" (DP. Given the high relevance of paleoclimatic reconstructions for policy-related studies, it is important for dendrochronologists to address this issue of potential model uncertainties associated with the DP. Here we address this issue by proposing a calibration technique, termed "stochastic response function" (SRF, which allows the presence or absence of any instabilities in growth response of trees (or any other climate proxy to their calibration target to be visualized and detected. Since this framework estimates confidence limits and subsequently provides statistical significance tests, the approach is also very well suited for proxy screening prior to the generation of a climate-reconstruction network.

Two examples of tree growth/climate relationships are provided, one from the North American Arctic treeline and the other from the upper treeline in the European Alps. Instabilities were found to be present where stabilities were reported in the literature, and vice versa, stabilities were found where instabilities were reported. We advise to apply SRFs in future proxy-screening schemes, next to the use of correlations and RE/CE statistics. It will improve the strength of reconstruction hindcasts.

Climate change indicators in the United States

Science.gov (United States)

2010-04-01

The U.S. Environmental Protection Agency (EPA) has published this report, Climate Change Indicators in the United States, to help readers interpret a set of important indicators to better understand climate change. The report presents 24 indicators, ...

Objective spatiotemporal proxy-model comparisons of the Asian monsoon for the last millennium

Science.gov (United States)

Anchukaitis, K. J.; Cook, E. R.; Ammann, C. M.; Buckley, B. M.; D'Arrigo, R. D.; Jacoby, G.; Wright, W. E.; Davi, N.; Li, J.

2008-12-01

The Asian monsoon system can be studied using a complementary proxy/simulation approach which evaluates climate models using estimates of past precipitation and temperature, and which subsequently applies the best understanding of the physics of the climate system as captured in general circulation models to evaluate the broad-scale dynamics behind regional paleoclimate reconstructions. Here, we use a millennial-length climate field reconstruction of monsoon season summer (JJA) drought, developed from tree- ring proxies, with coupled climate simulations from NCAR CSM1.4 and CCSM3 to evaluate the cause of large- scale persistent droughts over the last one thousand years. Direct comparisons are made between the external forced response within the climate model and the spatiotemporal field reconstruction. In order to identify patterns of drought associated with internal variability in the climate system, we use a model/proxy analog technique which objectively selects epochs in the model that most closely reproduce those observed in the reconstructions. The concomitant ocean-atmosphere dynamics are then interpreted in order to identify and understand the internal climate system forcing of low frequency monsoon variability. We examine specific periods of extensive or intensive regional drought in the 15th, 17th, and 18th centuries, many of which are coincident with major cultural changes in the region.

A multi-proxy analysis of Late Quaternary ocean and climate variability for the Maldives, Inner Sea

Science.gov (United States)

Bunzel, Dorothea; Schmiedl, Gerhard; Lindhorst, Sebastian; Mackensen, Andreas; Reolid, Jesús; Romahn, Sarah; Betzler, Christian

2017-12-01

As a natural sediment trap, the marine sediments of the sheltered central part of the Maldives Inner Sea represent an exceptional archive for paleoenvironmental and climate changes in the equatorial Indian Ocean. To evaluate the complex interplay between high-latitude and monsoonal climate variability, related dust fluxes, and regional oceanographic responses, we focused on Fe / Al, Ti / Al and Si / Ca ratios as proxies for terrigenous sediment delivery and total organic carbon (TOC) and Br XRF counts as proxies for marine productivity. Benthic foraminiferal fauna distributions, grain size and stable δ18O and δ13C data were used for evaluating changes in the benthic ecosystem and changes in the intermediate water circulation, bottom water current velocity and oxygenation. Our multi-proxy data record reveals an enhanced dust supply during the glacial intervals, causing elevated Fe / Al and Si / Ca ratios, an overall coarsening of the sediment and an increasing amount of agglutinated benthic foraminifera. The enhanced dust fluxes can be attributed to higher dust availability in the Asian desert and loess areas and its transport by intensified winter monsoon winds during glacial conditions. These combined effects of wind-induced mixing of surface waters and dust fertilization during the cold phases resulted in an increased surface water productivity and related organic carbon fluxes. Thus, the development of highly diverse benthic foraminiferal faunas with certain detritus and suspension feeders was fostered. The difference in the δ13C signal between epifaunal and deep infaunal benthic foraminifera reveals intermediate water oxygen concentrations between approximately 40 and 100 µmol kg-1 during this time. The precessional fluctuation pattern of oxygen changes resembles that from the deep Arabian Sea, suggesting an expansion of the oxygen minimum zone (OMZ) from the Arabian Sea into the tropical Indian Ocean with a probable regional signal of strengthened winter

Prompt Proxy Mapping of Flood Damaged Rice Fields Using MODIS-Derived Indices

Directory of Open Access Journals (Sweden)

Youngjoo Kwak

2015-11-01

Full Text Available Flood mapping, particularly hazard and risk mapping, is an imperative process and a fundamental part of emergency response and risk management. This paper aims to produce a flood risk proxy map of damaged rice fields over the whole of Bangladesh, where monsoon river floods are dominant and frequent, affecting over 80% of the total population. This proxy risk map was developed to meet the request of the government on a national level. This study represents a rapid, straightforward methodology for estimating rice-crop damage in flood areas of Bangladesh during the large flood from July to September 2007, despite the lack of primary data. We improved a water detection algorithm to achieve a better discrimination capacity to discern flood areas by using a modified land surface water index (MLSWI. Then, rice fields were estimated utilizing a hybrid rice field map from land-cover classification and MODIS-derived indices, such as the normalized difference vegetation index (NDVI and enhanced vegetation index (EVI. The results showed that the developed method is capable of providing instant, comprehensive, nationwide mapping of flood risks, such as rice field damage. The detected flood areas and damaged rice fields during the 2007 flood were verified by comparing them with the Advanced Land Observing Satellite (ALOS AVNIR-2 images (a 10 m spatial resolution and in situ field survey data with moderate agreement (K = 0.57.

Environmental proxies of antigen exposure explain variation in immune investment better than indices of pace of life.

Science.gov (United States)

Horrocks, Nicholas P C; Hegemann, Arne; Ostrowski, Stéphane; Ndithia, Henry; Shobrak, Mohammed; Williams, Joseph B; Matson, Kevin D; Tieleman, B I

2015-01-01

Investment in immune defences is predicted to covary with a variety of ecologically and evolutionarily relevant axes, with pace of life and environmental antigen exposure being two examples. These axes may themselves covary directly or inversely, and such relationships can lead to conflicting predictions regarding immune investment. If pace of life shapes immune investment then, following life history theory, slow-living, arid zone and tropical species should invest more in immunity than fast-living temperate species. Alternatively, if antigen exposure drives immune investment, then species in antigen-rich tropical and temperate environments are predicted to exhibit higher immune indices than species from antigen-poor arid locations. To test these contrasting predictions we investigated how variation in pace of life and antigen exposure influence immune investment in related lark species (Alaudidae) with differing life histories and predicted risks of exposure to environmental microbes and parasites. We used clutch size and total number of eggs laid per year as indicators of pace of life, and aridity, and the climatic variables that influence aridity, as correlates of antigen abundance. We quantified immune investment by measuring four indices of innate immunity. Pace of life explained little of the variation in immune investment, and only one immune measure correlated significantly with pace of life, but not in the predicted direction. Conversely, aridity, our proxy for environmental antigen exposure, was predictive of immune investment, and larks in more mesic environments had higher immune indices than those living in arid, low-risk locations. Our study suggests that abiotic environmental variables with strong ties to environmental antigen exposure can be important correlates of immunological variation.

TEX86 paleothermometry : proxy validation and application in marine sediments

NARCIS (Netherlands)

Huguet, C.

2007-01-01

Determination of past sea surface temperature (SST) is of primary importance for the reconstruction of natural climatic changes, modelling of climate and reconstruction of ocean circulation. Recently, a new SST proxy was introduced, the TetraEther indeX of lipids with 86 carbons (TEX86), which is

TEX₈₆ paleothermometry : proxy validation and application in marine sediments

NARCIS (Netherlands)

Huguet, Carme

2007-01-01

Determination of past sea surface temperature (SST) is of primary importance for the reconstruction of natural climatic changes, modelling of climate and reconstruction of ocean circulation. Recently, a new SST proxy was introduced, the TetraEther indeX of lipids with 86 carbons (TEX₈₆), which is

Climate Change Impacts and Responses: Societal Indicators for the National Climate Assessment

Science.gov (United States)

Kenney, Melissa A.; Chen, Robert S.; Maldonado, Julie; Quattrochi, Dale

2011-01-01

The Climate Change Impacts and Responses: Societal Indicators for the National Climate Assessment workshop, sponsored by the National Aeronautics and Space Administration (NASA) for the National Climate Assessment (NCA), was held on April 28-29, 2011 at The Madison Hotel in Washington, DC. A group of 56 experts (see list in Appendix B) convened to share their experiences. Participants brought to bear a wide range of disciplinary expertise in the social and natural sciences, sector experience, and knowledge about developing and implementing indicators for a range of purposes. Participants included representatives from federal and state government, non-governmental organizations, tribes, universities, and communities. The purpose of the workshop was to assist the NCA in developing a strategic framework for climate-related physical, ecological, and socioeconomic indicators that can be easily communicated with the U.S. population and that will support monitoring, assessment, prediction, evaluation, and decision-making. The NCA indicators are envisioned as a relatively small number of policy-relevant integrated indicators designed to provide a consistent, objective, and transparent overview of major variations in climate impacts, vulnerabilities, adaptation, and mitigation activities across sectors, regions, and timeframes. The workshop participants were asked to provide input on a number of topics, including: (1) categories of societal indicators for the NCA; (2) alternative approaches to constructing indicators and the better approaches for NCA to consider; (3) specific requirements and criteria for implementing the indicators; and (4) sources of data for and creators of such indicators. Socioeconomic indicators could include demographic, cultural, behavioral, economic, public health, and policy components relevant to impacts, vulnerabilities, and adaptation to climate change as well as both proactive and reactive responses to climate change. Participants provided

Climate indicators for Italy: calculation and dissemination

Science.gov (United States)

Desiato, F.; Fioravanti, G.; Fraschetti, P.; Perconti, W.; Toreti, A.

2011-05-01

In Italy, meteorological data necessary and useful for climate studies are collected, processed and archived by a wide range of national and regional institutions. As a result, the density of the stations, the length and frequency of the observations, the quality control procedures and the database structure vary from one dataset to another. In order to maximize the use of those data for climate knowledge and climate change assessments, a computerized system for the collection, quality control, calculation, regular update and rapid dissemination of climate indicators was developed. The products publicly available through a dedicated web site are described, as well as an example of climate trends estimates over Italy, based on the application of statistical models on climate indicators from quality-checked and homogenised time series.

Evaluation of the sea ice proxy IP against observational and diatom proxy data in the SW Labrador Sea

DEFF Research Database (Denmark)

Weckström, K.; Andersen, M.L.; Kuijpers, A.

2013-01-01

The recent rapid decline in Arctic sea ice cover has increased the need to improve the accuracy of the sea ice component in climate models and to provide detailed long-term sea ice concentration records, which are only available via proxy data. Recently, the highly branched isoprenoid IP25...

CCME Climate Change Indicators -- Workshop Report

International Nuclear Information System (INIS)

2000-01-01

In an effort to give Canadians a better understanding of the climate change issue, in 1999 the Canadian Council of Ministers of the Environment (CCME) established a Project Working Group to identify and assemble a set of climate change indicators that is scientifically valid, useful and meaningful to the public. To ensure the widest possible participation of experts from all parts of the country the Project Working Group convened a two-day workshop in Toronto to take place on the 6th and 7th of November 2000. The outcome of the workshop, summarized in this report, resulted in a 'Made in Canada' framework of indicators for climate change impacts, divided into five categories: physical environment, personal health and safety, jobs and economic well-being, social and community well-being, and eco-system health. The report contains highlights of the discussions. There are seven appendices containing, respectively, a series of pre-workshop suggestions for indicators (Appendix A), the workshop agenda and backgrounder (Appendix B), a list of participants (Appendix C), presentation slides on the Canada country study (Appendix D), existing and proposed climate change indicators (Appendix E), presentation slides on communication issues (Appendix F), and notes summarizing small group discussions, including assessment of the level of interest demonstrated and opinions expressed by group members about the utility and value of each of the proposed indicators (Appendix G)

Decade to centennial resolution hydrogen isotopic record of climate change from southern New England for the past 16 kyr: proxy validation and multi-proxy comparisons

Science.gov (United States)

Huang, Y.; Gao, L.; Hou, J.; Shuman, B. N.; Oswald, W.; Foster, D.

2009-12-01

Open system lakes in New England offer excellent archives of precipitation isotopic ratios that yield quantitative paleoclimate information. We have demonstrated previously from a lake sediment transect that hydrogen isotopic ratios of a middle-chain length fatty acid, behenic acid (BA), faithfully record precipitation isotopic ratios. We hypothesized that mid-chain n-alkyl lipids in these small lakes were primarily derived from aquatic plants that record lake water isotopic ratios. To test this hypothesis, we conducted systematic and extensive sampling of both terrestrial and aquatic plants over the past two years at two typical kettle hole lakes, Blood Pond and Rocky Pond, MA, and used a linear algebra approach to delineate percentage inputs of aquatic and terrestrial plant contributions to mid-chain n-alkyl lipids. Our results demonstrate that >92 % of the mid-chain n-alkyl lipids is derived from submerged and floating aquatic macrophytes. Our new data provide a solid basis for the application of behenic hydrogen isotopic ratios as a paleoclimate proxy from small lakes. We will present a decadal to centennial scale 16 kyr record of BA hydrogen isotopic ratios from Blood Pond, and will discuss the results in light of published pollen and lake level data. Overall, our hydrogen isotopic record is fully consistent with regional climate scenarios, including the distinctive warming at B-A events, abrupt cooling at YD event, and transition from glacial to Holcoene climate conditions. However, our high-solution isotopic data provides important new insights concerning abrupt regional climate variability. We demonstrate that the New England climate is exceptionally senstive to AMOC changes and solar forcing and that many of the abrupt climate fluctuations exert major impacts on terrestrial ecosystems, hydrology and lake levels.

Reconstructing Holocene climate using a climate model: Model strategy and preliminary results

Science.gov (United States)

Haberkorn, K.; Blender, R.; Lunkeit, F.; Fraedrich, K.

2009-04-01

An Earth system model of intermediate complexity (Planet Simulator; PlaSim) is used to reconstruct Holocene climate based on proxy data. The Planet Simulator is a user friendly general circulation model (GCM) suitable for palaeoclimate research. Its easy handling and the modular structure allow for fast and problem dependent simulations. The spectral model is based on the moist primitive equations conserving momentum, mass, energy and moisture. Besides the atmospheric part, a mixed layer-ocean with sea ice and a land surface with biosphere are included. The present-day climate of PlaSim, based on an AMIP II control-run (T21/10L resolution), shows reasonable agreement with ERA-40 reanalysis data. Combining PlaSim with a socio-technological model (GLUES; DFG priority project INTERDYNAMIK) provides improved knowledge on the shift from hunting-gathering to agropastoral subsistence societies. This is achieved by a data assimilation approach, incorporating proxy time series into PlaSim to initialize palaeoclimate simulations during the Holocene. For this, the following strategy is applied: The sensitivities of the terrestrial PlaSim climate are determined with respect to sea surface temperature (SST) anomalies. Here, the focus is the impact of regionally varying SST both in the tropics and the Northern Hemisphere mid-latitudes. The inverse of these sensitivities is used to determine the SST conditions necessary for the nudging of land and coastal proxy climates. Preliminary results indicate the potential, the uncertainty and the limitations of the method.

Generating and Visualizing Climate Indices using Google Earth Engine

Science.gov (United States)

Erickson, T. A.; Guentchev, G.; Rood, R. B.

2017-12-01

Climate change is expected to have largest impacts on regional and local scales. Relevant and credible climate information is needed to support the planning and adaptation efforts in our communities. The volume of climate projections of temperature and precipitation is steadily increasing, as datasets are being generated on finer spatial and temporal grids with an increasing number of ensembles to characterize uncertainty. Despite advancements in tools for querying and retrieving subsets of these large, multi-dimensional datasets, ease of access remains a barrier for many existing and potential users who want to derive useful information from these data, particularly for those outside of the climate modelling research community. Climate indices, that can be derived from daily temperature and precipitation data, such as annual number of frost days or growing season length, can provide useful information to practitioners and stakeholders. For this work the NASA Earth Exchange Global Daily Downscaled Projections (NEX-GDDP) dataset was loaded into Google Earth Engine, a cloud-based geospatial processing platform. Algorithms that use the Earth Engine API to generate several climate indices were written. The indices were chosen from the set developed by the joint CCl/CLIVAR/JCOMM Expert Team on Climate Change Detection and Indices (ETCCDI). Simple user interfaces were created that allow users to query, produce maps and graphs of the indices, as well as download results for additional analyses. These browser-based interfaces could allow users in low-bandwidth environments to access climate information. This research shows that calculating climate indices from global downscaled climate projection datasets and sharing them widely using cloud computing technologies is feasible. Further development will focus on exposing the climate indices to existing applications via the Earth Engine API, and building custom user interfaces for presenting climate indices to a diverse set of

Satellite Altimeters and Gravimeters as Proxy of the Indonesian Throughflow

Science.gov (United States)

Susanto, R. D.; Song, Y. T.

2014-12-01

The Indonesian Throughflow (ITF), the only pathway for interocean exchange between the Pacific to the Indian Ocean, plays an important role in global ocean circulation and climate. Yet, continuous ITF measurement is difficult and expensive. We demonstrate a plausible approach to derive the ITF transport proxy using satellite altimetry sea surface height (SSH), gravimetry ocean bottom pressure (OBP) data, in situ measurements from the Makassar Strait from 1996-1998 and 2004-2009, and a theoretical formulation. We first identified the optimal locations in the Pacific and Indian Ocean based on the optimal correlation between the ITF transport through the Makassar Strait and the pressure gradients, represented by the SSH and OBP differences between the Pacific and Indian Oceans at a 1° x 1° horizontal resolution. These geographical locations (centred at off-equatorial in the western Pacific Ocean and centred at along the equator in the eastern Indian Ocean) that control the strength and variability of the ITF transport in the Makassar Strait differ from early studies. The proxy time series follow the observation time series quite well, resolving the intraseasonal, monsoonal, and interannual signals with the 1993-2011 annual mean proxy transport of 11.6 ± 3.2 Sv. Our formulation provides a continuous approach to derive the ITF proxy as long as the satellite data are available. Such a continuous record would be difficult to achieve by in situ measurements alone due to logistical and financial challenges. Ideally, the proxy can be used to complement or fill in the gaps of the observations for a continuous ITF proxy for better understanding the ocean climate and validating ocean circulation models.

Climatic and anthropogenic controls on Mississippi River floods: a multi-proxy palaeoflood approach

Science.gov (United States)

Munoz, S. E.; Therrell, M. D.; Remo, J. W.; Giosan, L.; Donnelly, J. P.

2017-12-01

Over the last century, many of the world's major rivers have been modified for the purposes of flood mitigation, power generation, and commercial navigation. Engineering modifications to the Mississippi River system have altered the river's sediment budget and channel morphology, but the influence of these modifications on flood risk is debated. Detecting and attributing changes in river discharge is challenging because instrumental streamflow records are often too short to evaluate the range of natural hydrological variability prior to the establishment of flood mitigation infrastructure. Here we show that multi-decadal trends of flood risk on the lower Mississippi River are strongly modulated by dynamical modes of climate variability, particularly the El Niño-Southern Oscillation (ENSO) and the Atlantic Multidecadal Oscillation (AMO), but that artificial channelization has greatly amplified flood magnitudes over the last century. Our results, based on a multi-proxy reconstruction of flood frequency and magnitude spanning the last five hundred years that combines sedimentary, tree-ring, and instrumental records, reveal that the magnitude of the 100-year flood has increased by 20% over the period of record, with 75% of this increase attributed to river engineering. We conclude that the interaction of human alterations to the Mississippi River system with dynamical modes of climate variability has elevated the current flood risk to levels that are unprecedented within the last five centuries.

Calcium isotopic composition of high-latitude proxy carrier Neogloboquadrina pachyderma (sin.

Directory of Open Access Journals (Sweden)

A. Eisenhauer

2009-01-01

Full Text Available The accurate reconstruction of sea surface temperature (SST history in climate-sensitive regions (e.g. tropical and polar oceans became a challenging task in palaeoceanographic research. Biogenic shell carbonate SST proxies successfully developed for tropical regions often fail in cool water environments. Their major regional shortcomings and the cryptic diversity now found within the major high latitude proxy carrier Neogloboquadrina pachyderma (sin. highlight an urgent need to explore complementary SST proxies for these cool-water regions. Here we incorporate the genetic component into a calibration study of a new SST proxy for the high latitudes. We found that the calcium isotopic composition (δ44/40Ca of calcite from genotyped net catches and core-top samples of the planktonic foraminifera Neogloboquadrina pachyderma (sin. is related to temperature and unaffected by genetic variations. The temperature sensitivity has been found to be 0.17 (±0.02‰ per 1°C, highlighting its potential for downcore applications in open marine cool-water environments. Our results further indicate that in extreme polar environments, below a critical threshold temperature of 2.0 (±0.5°C associated with salinities below 33.0 (±0.5‰, a prominent shift in biomineralization affects the δ44/40Ca of genotyped and core-top N. pachyderma (sin., becoming insensitive to temperature. These findings highlight the need of more systematic calibration studies on single planktonic foraminiferal species in order to unravel species-specific factors influencing the temperature sensitivity of Ca isotope fractionation and to validate the proxies' applicability.

Technical Note: Probabilistically constraining proxy age–depth models within a Bayesian hierarchical reconstruction model

Directory of Open Access Journals (Sweden)

J. P. Werner

2015-03-01

Full Text Available Reconstructions of the late-Holocene climate rely heavily upon proxies that are assumed to be accurately dated by layer counting, such as measurements of tree rings, ice cores, and varved lake sediments. Considerable advances could be achieved if time-uncertain proxies were able to be included within these multiproxy reconstructions, and if time uncertainties were recognized and correctly modeled for proxies commonly treated as free of age model errors. Current approaches for accounting for time uncertainty are generally limited to repeating the reconstruction using each one of an ensemble of age models, thereby inflating the final estimated uncertainty – in effect, each possible age model is given equal weighting. Uncertainties can be reduced by exploiting the inferred space–time covariance structure of the climate to re-weight the possible age models. Here, we demonstrate how Bayesian hierarchical climate reconstruction models can be augmented to account for time-uncertain proxies. Critically, although a priori all age models are given equal probability of being correct, the probabilities associated with the age models are formally updated within the Bayesian framework, thereby reducing uncertainties. Numerical experiments show that updating the age model probabilities decreases uncertainty in the resulting reconstructions, as compared with the current de facto standard of sampling over all age models, provided there is sufficient information from other data sources in the spatial region of the time-uncertain proxy. This approach can readily be generalized to non-layer-counted proxies, such as those derived from marine sediments.

New directions in hydro-climatic histories: observational data recovery, proxy records and the atmospheric circulation reconstructions over the earth (ACRE) initiative in Southeast Asia

Science.gov (United States)

Williamson, Fiona; Allan, Rob; Switzer, Adam D.; Chan, Johnny C. L.; Wasson, Robert James; D'Arrigo, Rosanne; Gartner, Richard

2015-12-01

The value of historic observational weather data for reconstructing long-term climate patterns and the detailed analysis of extreme weather events has long been recognized (Le Roy Ladurie, 1972; Lamb, 1977). In some regions however, observational data has not been kept regularly over time, or its preservation and archiving has not been considered a priority by governmental agencies. This has been a particular problem in Southeast Asia where there has been no systematic country-by-country method of keeping or preserving such data, the keeping of data only reaches back a few decades, or where instability has threatened the survival of historic records. As a result, past observational data are fragmentary, scattered, or even absent altogether. The further we go back in time, the more obvious the gaps. Observational data can be complimented however by historical documentary or proxy records of extreme events such as floods, droughts and other climatic anomalies. This review article highlights recent initiatives in sourcing, recovering, and preserving historical weather data and the potential for integrating the same with proxy (and other) records. In so doing, it focuses on regional initiatives for data research and recovery - particularly the work of the international Atmospheric Circulation Reconstructions over the Earth's (ACRE) Southeast Asian regional arm (ACRE SEA) - and the latter's role in bringing together disparate, but interrelated, projects working within this region. The overarching goal of the ACRE SEA initiative is to connect regional efforts and to build capacity within Southeast Asian institutions, agencies and National Meteorological and Hydrological Services (NMHS) to improve and extend historical instrumental, documentary and proxy databases of Southeast Asian hydroclimate, in order to contribute to the generation of high-quality, high-resolution historical hydroclimatic reconstructions (reanalyses) and, to build linkages with humanities researchers

Magnetic record associated with tree ring density: Possible climate proxy

Czech Academy of Sciences Publication Activity Database

Kletetschka, Günther; Pruner, Petr; Venhodová, Daniela; Kadlec, Jaroslav

2007-01-01

Roč. 8, - (2007), s. 1-11 ISSN 1467-4866 Institutional research plan: CEZ:AV0Z3013912 Keywords : palaeo-climatic indicator * sequoia tree * magnetic properties Subject RIV: DB - Geology ; Mineralogy Impact factor: 1.842, year: 2007

Communicating global climate change using simple indices: an update

Energy Technology Data Exchange (ETDEWEB)

Drost, Frank; Karoly, David [University of Melbourne, School of Earth Sciences, Melbourne, VIC (Australia); Braganza, Karl [National Climate Centre, Bureau of Meteorology, Melbourne, VIC (Australia)

2012-08-15

Previous studies have shown that there are several indices of global-scale temperature variations, in addition to global-mean surface air temperature, that are useful for distinguishing natural internal climate variations from anthropogenic climate change. Appropriately defined, such indices have the ability to capture spatio-temporal information in a similar manner to optimal fingerprints of climate change. These indices include the contrast between the average temperatures over land and over oceans, the Northern Hemisphere meridional temperature gradient, the temperature contrast between the Northern and Southern Hemisphere and the magnitude of the annual cycle of average temperatures over land. They contain information independent of the global-mean temperature for internal climate variations at decadal time scales and represent different aspects of the climate system, yet they show common responses to anthropogenic climate change. In addition, the ratio of average temperature changes over land to those over the oceans should be nearly constant for transient climate change. Hence, supplementing analysis of global-mean surface temperature with analyses of these indices can strengthen results of attribution studies of causes of observed climate variations. In this study, we extend the previous work by including the last 10 years of observational data and the CMIP3 climate model simulations analysed for the IPCC AR4. We show that observed changes in these indices over the last 10 years provide increased evidence of an anthropogenic influence on climate. We also show the usefulness of these indices for evaluating the performance of climate models in simulating large-scale variability of surface temperature. (orig.)

Indexes of leading climate indicators for impact assessment

International Nuclear Information System (INIS)

Easterling, W.E.; Kates, R.W.

1995-01-01

Could users of climate information for impact assessment be overlooking an important source of information in climate indicators? We argue that indexes of leading climate indicators of impacts may be usable knowledge for consumers and may provide guidance to the global climate observing community concerning the types of data and information that users need. Five classes of indexes are suggested: Climate Extremes Index (CEI) and Greenhouse Climate Response Index (GCRI) - such are already available from scientists at the US National Climatic Data Center - plus proposed indexes of Hazard Warning, Ecosystem Health, and Energy Demand and Renewable Natural Resources. We conclude that the CEI and GCRI posses several necessary attributes to become usable knowledge; the other indexes have the potential to become usable knowledge, but remain to be implemented with climate data and fully evaluated. 34 refs

Quantitative use of Palaeo-Proxy Data in Global Circulation Models

Science.gov (United States)

Collins, M.

2003-04-01

It is arguably one of the ultimate aims of palaeo-modelling science to somehow "get the palaeo-proxy data into the model" i.e. to constrain the climate of the model the trajectory of the real climate recorded in the palaeo data. The traditional way of interfacing data with models is to use data assimilation. This presents a number of problems in the palaeo context as the data are more often representative of seasonal to annual or decadal climate and models have time steps of order minutes, hence the model increments are likely to be vanishingly small. Also, variational data assimilation schemes would require the adjoint of the coupled ocean-atmosphere model and the adjoint of the functions which translate model variables such as temperature and precipitation into the palaeo-proxies, both of which are hard to determine because of the high degree of non-linearity in the system and the wide range of space and time scales. An alternative is to add forward models of proxies to the model and run "many years" of simulation until an analog state is found which matches the palaeo data for each season, year, decade etc. Clearly "many years" might range from a few thousand years to almost infinity and depends on the number of degrees of freedom in the climate system and on the error characteristics of the palaeo data. The length of simulation required is probably beyond the supercomputer capacity of a single institution and hence an alternative is to use idle capacity of home and business personal computers - the climateprediction.net project.

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

Digital Repository Service at National Institute of Oceanography (India)

Gupta, S.M.

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

Validity of proxies and correction for proxy use when evaluating social determinants of health in stroke patients.

Science.gov (United States)

Skolarus, Lesli E; Sánchez, Brisa N; Morgenstern, Lewis B; Garcia, Nelda M; Smith, Melinda A; Brown, Devin L; Lisabeth, Lynda D

2010-03-01

The purpose of this study was to evaluate stroke patient-proxy agreement with respect to social determinants of health, including depression, optimism, and spirituality, and to explore approaches to minimize proxy-introduced bias. Stroke patient-proxy pairs from the Brain Attack Surveillance in Corpus Christi Project were interviewed (n=34). Evaluation of agreement between patient-proxy pairs included calculation of intraclass correlation coefficients, linear regression models (ProxyResponse=alpha(0)+alpha(1)PatientResponse+delta, where alpha(0)=0 and alpha(1)=1 denotes no bias) and kappa statistics. Bias introduced by proxies was quantified with simulation studies. In the simulated data, we applied 4 approaches to estimate regression coefficients of stroke outcome social determinants of health associations when only proxy data were available for some patients: (1) substituting proxy responses in place of patient responses; (2) including an indicator variable for proxy use; (3) using regression calibration with external validation; and (4) internal validation. Agreement was fair for depression (intraclass correlation coefficient, 0.41) and optimism (intraclass correlation coefficient, 0.48) and moderate for spirituality (kappa, 0.48 to 0.53). Responses of proxies were a biased measure of the patients' responses for depression, with alpha(0)=4.88 (CI, 2.24 to 7.52) and alpha(1)=0.39 (CI, 0.09 to 0.69), and for optimism, with alpha(0)=3.82 (CI, -1.04 to 8.69) and alpha(1)=0.81 (CI, 0.41 to 1.22). Regression calibration with internal validation was the most accurate method to correct for proxy-induced bias. Fair/moderate patient-proxy agreement was observed for social determinants of health. Stroke researchers who plan to study social determinants of health may consider performing validation studies so corrections for proxy use can be made.

Reliability and usability of tourism climate indices

Directory of Open Access Journals (Sweden)

Ghislain Dubois

2016-04-01

Full Text Available Abstract Tourism climate indices (TCI are commonly used to describe the climate conditions suitable for tourism activities, from the planning, investment or daily operations perspectives. A substantial amount of research has been carried out, in particular with respect to new indices formulae adapted to specific tourism products, and parameters and their weighting, taking into account surveys on the stated preferences of tourists, especially in terms of comfort. This paper illustrates another field of research, which seeks to better understand the different sources of uncertainty associated with indices. Indeed, slight differences in formula thresholds, variations in computation methods, and also the use of multimodel ensembles create nuances that affect the ways in which indices projections are usually presented. Firstly, we assess the impact of differences in preference surveys on the definition of indices thresholds, in particular for thermal comfort. Secondly, we compare computation methods for France, showing the need to better specify detailed data sources and their use to ensure the comparability of results. Thirdly, using multimodel ensembles for the Mediterranean basin, we assess the uncertainty inherent in long-term projections, which are used in modelling the economic impact of climate change. This paper argues in favour of a more cautious use of tourism comfort indices, with more consideration given to the robustness of data (validation, debiasing, uncertainty assessment, etc. and users’ needs, from the climate services perspective.

WOOD CELLULAR DENDROCLIMATOLOGY: TESTING NEW PROXIES IN GREAT BASIN BRISTLECONE PINE

Directory of Open Access Journals (Sweden)

Emanuele Ziaco

2016-10-01

Full Text Available Dendroclimatic proxies can be generated from the analysis of wood cellular structures, allowing for a more complete understanding of the physiological mechanisms that control the climatic response of tree species. Century-long (1870-2013 time series of anatomical parameters were developed for Great Basin bristlecone pine (Pinus longaeva D.K. Bailey by capturing strongly contrasted microscopic images through a Confocal Laser Scanning Microscope. Environmental information embedded in wood anatomical series was analyzed in comparison with ring-width series using measures of empirical signal strength. Response functions were calculated against monthly climatic variables to evaluate climate sensitivity of cellular features (e.g. lumen area; lumen diameter for the period 1950-2013. Calibration-verification tests were used to determine the potential to generate long climate reconstructions from these anatomical proxies. A total of eight tree-ring parameters (two ring-width and six chronologies of xylem anatomical parameters were analyzed. Synchronous variability among samples varied among tree-ring parameters, usually decreasing from ring width to anatomical features. Cellular parameters linked to plant hydraulic performance (e.g. tracheid lumen area and radial lumen diameter showed empirical signal strength similar to ring-width series, while noise was predominant in chronologies of lumen tangential width and cell-wall thickness. Climatic signals were different between anatomical and ring-width chronologies, revealing a positive and temporally stable correlation of tracheid size (i.e. lumen and cell diameter with monthly (i.e. March and seasonal precipitation. In particular, tracheid lumen diameter emerged as a reliable moisture indicator and was then used to reconstruct total March-August precipitation from 1870 to 2013. Wood anatomy holds great potential to refine and expand dendroclimatic records by allowing estimates of plant physiological

A 13000-year, high-resolution multi-proxy record of climate variability with episodes of enhanced atmospheric dust in Western Asia: Evidence from Neor peat complex in NW Iran

Science.gov (United States)

Sharifi, O.; Pourmand, A.; Canuel, E. A.; Peterson, L. C.

2011-12-01

The regional climate over West Asia, extending between Iran and the Arabian Peninsula to the eastern Mediterranean Sea, is governed by interactions between three major synoptic systems; mid-latitude Westerlies, the Siberian Anticyclone and the Indian Ocean Summer Monsoon. In recent years, a number of paleoclimate studies have drawn potential links between episodes of abrupt climate change during the Holocene, and the rise and fall of human civilizations across the "Fertile Crescent" of West Asia. High-resolution archives of climate variability from this region, however, are scarce, and at times contradicting. For example, while pollen and planktonic data from lakes in Turkey and Iran suggest that dry, continental conditions prevailed during the early-middle Holocene, oxygen isotope records indicate that relatively wet conditions dominated during this interval over West Asia. We present interannual to decadal multi-proxy records of climate variability from a peat complex in NW Iran to reconstruct changes in moisture and atmospheric dust content during the last 13000 years. Radiocarbon dating on 20 samples from a 775-cm peat core show a nearly constant rate of accumulation (1.7 mm yr-1, R2=0.99) since 13356 ± 116 cal yr B.P. Down-core X-ray fluorescence measurements of conservative lithogenic elements (e.g., Al, Zr, Ti) as well as redox-sensitive elements (e.g., Fe, K, Rb, Zn, Cu, and Co) at 2 mm intervals reveal several periods of elevated dust input to this region since the early Holocene. Down-core variations of total organic carbon and total nitrogen co-vary closely and are inversely correlated with conservative lithogenic elements (Al, Si, Ti), indicating a potential link between climate change and accumulation of organic carbon in the Neor peat mire. Major episodes of enhanced dust deposition (13000-12000, 11700-11200, 9200-8800, 7000-6000, 4200-3200, 2800-2200 and 1500-600 cal yr B.P) are in good agreement with other proxy records that document more arid

Bayesian hierarchical models for regional climate reconstructions of the last glacial maximum

Science.gov (United States)

Weitzel, Nils; Hense, Andreas; Ohlwein, Christian

2017-04-01

Spatio-temporal reconstructions of past climate are important for the understanding of the long term behavior of the climate system and the sensitivity to forcing changes. Unfortunately, they are subject to large uncertainties, have to deal with a complex proxy-climate structure, and a physically reasonable interpolation between the sparse proxy observations is difficult. Bayesian Hierarchical Models (BHMs) are a class of statistical models that is well suited for spatio-temporal reconstructions of past climate because they permit the inclusion of multiple sources of information (e.g. records from different proxy types, uncertain age information, output from climate simulations) and quantify uncertainties in a statistically rigorous way. BHMs in paleoclimatology typically consist of three stages which are modeled individually and are combined using Bayesian inference techniques. The data stage models the proxy-climate relation (often named transfer function), the process stage models the spatio-temporal distribution of the climate variables of interest, and the prior stage consists of prior distributions of the model parameters. For our BHMs, we translate well-known proxy-climate transfer functions for pollen to a Bayesian framework. In addition, we can include Gaussian distributed local climate information from preprocessed proxy records. The process stage combines physically reasonable spatial structures from prior distributions with proxy records which leads to a multivariate posterior probability distribution for the reconstructed climate variables. The prior distributions that constrain the possible spatial structure of the climate variables are calculated from climate simulation output. We present results from pseudoproxy tests as well as new regional reconstructions of temperatures for the last glacial maximum (LGM, ˜ 21,000 years BP). These reconstructions combine proxy data syntheses with information from climate simulations for the LGM that were

A New Revision of the Solar Irradiance Climate Data Record Incorporates Recent Research into Proxies of Sunspot Darkening and the Sunspot Number Record

Science.gov (United States)

Coddington, O.; Lean, J.; Pilewskie, P.; Baranyi, T.; Snow, M. A.; Kopp, G.; Richard, E. C.; Lindholm, C.

2017-12-01

An operational climate data record (CDR) of total and spectral solar irradiance became available in November 2015 as part of the National Oceanographic and Atmospheric Administration's National Centers for Environmental Information Climate Data Record Program. The data record, which is updated quarterly, is available from 1610 to the present as yearly-average values and from 1882 to the present as monthly- and daily-averages, with associated time and wavelength-dependent uncertainties. It was developed jointly by the University of Colorado at Boulder's Laboratory for Atmospheric and Space Physics and the Naval Research Laboratory, and, together with the source code and supporting documentation, is available at https://www.ncdc.noaa.gov/cdr/. In the Solar Irradiance CDR, total solar irradiance (TSI) and solar spectral irradiance (SSI) are estimated from models that determine the changes from quiet Sun conditions arising from bright faculae and dark sunspots on the solar disk. The models are constructed using linear regression of proxies of solar sunspot and facular features with the approximately decade-long irradiance observations from the SOlar Radiation and Climate Experiment. A new revision of this data record was recently released in an ongoing effort to reduce solar irradiance uncertainties in two ways. First, the sunspot darkening proxy was revised using a new cross calibration of the current sunspot region observations made by the Solar Observing Optical Network with the historical records of the Royal Greenwich Observatory. This implementation affects modeled irradiances from 1882 - 1978. Second, the impact of a revised record of sunspot number by the Sunspot Index and Long-term Solar Observations center on modeled irradiances was assessed. This implementation provides two different reconstructions of historical, yearly-averaged irradiances from 1610-1881. Additionally, we show new, preliminary results that demonstrate improvements in modeled TSI by using

The potential of the baobab (Adansonia digitata L.) as a proxy climate archive

International Nuclear Information System (INIS)

Robertson, I.; Loader, N.J.; Froyd, C.A.; Zambatis, N.; Whyte, I.; Woodborne, S.

2006-01-01

The large girth and immense size of the baobab has caused many to speculate about its age. Unfortunately reliable age estimates cannot be determined from growth rates as the girth varies in response to different moisture regimes. In a similar way, ages cannot be determined from ring-width measurements or X-ray densitometry as the absorbent nature of the soft fibrous wood and distortion upon drying prevent the application of these techniques. The Southern Hemisphere bomb radiocarbon curve was used to demonstrate that the rings of a recently-fallen baobab (Adansonia digitata L.) from Kruger National Park appear to be annual. The detrended C isotope values of finely-ground wholewood from another baobab specimen were found to be highly associated with January precipitation (r = 0.72; p < 0.01). This study demonstrates that high resolution information about past climates may be obtained by analysing the C isotope values from baobab samples even if distortion of ring-widths has occurred during drying. However, this relationship must be replicated before the baobab can be demonstrated to be a reliable palaeoclimatic proxy

Bridging the spectral divide: a case study with PAGES2k, the CESM Last Millennium Ensemble and proxy system models

Science.gov (United States)

Zhu, F.; Emile-Geay, J.; Ault, T.; McKay, N.; Dee, S.

2017-12-01

A grand challenge for paleoclimatology is to constrain climate model behavior on timescales longer than the instrumental record. Of particular interest is the spectrum of temperature as sensed by climate proxies. The "continuum" of climate variability [Huybers & Curry, Nature 2006] is often characterized by its scaling exponent β , where the spectral density S and the frequency f satisfy the power law S ∝ f-β . Recent studies have voiced concern that climate models underestimate scaling behavior compared to proxies [Laepple & Huybers, PNAS 2014]. Part of this discrepancy is known to lie in the complex processes whereby proxies transform climate signals [Dee et al, EPSL in press], yet many questions remain open. Here we leverage a recent multiproxy compilation [PAGES 2k Consortium, Sci Data 2017] to characterize scaling behavior over the Common Era using an interpolation-free method [Kirchner & Neal, PNAS 2013]. Proxy spectra are compared to spectra derived from the CESM Last Millennium Ensemble [Otto-Bliesner et al, BAMS 2016], using: (a) a naive model where proxies are assumed linearly related to annual temperature vs (b) proxy system models [Evans et al, QSR 2013] of varying complexity. Scaling behavior varies considerably by archive: on average the strongest centennial slopes are observed for lake sediments (β =1.2), while the smallest are observed for glacier ice (β =0.24). Results confirm that the CESM Last Millennium simulation (LM) exhibits decadal-centennial scaling closer to proxy spectra than the pre-industrial control run (PI): the latter shows a "blue" spectrum (β 0), suggesting that forcings are essential to reduce the spectral divide. Yet, even with forcings, LM spectra are flatter than the proxy spectra. Subsequent work will investigate the roles of seasonal sensitivity (trees, foraminifera, alkenones), multivariate influences (corals, trees), detrending (trees) and post-depositional processes (ice cores, lake & marine sediments) on spectral

Multi-proxy reconstructions and the power of integration across marine, terrestrial, and freshwater ecosystems. (Invited)

Science.gov (United States)

Black, B.

2013-12-01

Over the past decade, dendrochronology (tree-ring analysis) techniques have been increasingly applied to growth increments of various bivalve, fish, and coral species. In particular, the use of crossdating ensures that all increments in a dataset have assigned the correct calendar year of formation and that the resulting chronology is exactly placed in time. Such temporal alignment facilitates direct comparisons among chronologies that span diverse taxa and ecosystems, illustrating the pervasive, synchronizing influence of climate from alpine forests to the continental slope. Such an approach can be particularly beneficial to reconstructions in that each species captures climate signals from its unique 'perspective' of life history and habitat. For example, combinations of tree-ring data and chronologies for the long-lived bivalve Pacific geoduck (Panopea generosa) capture substantially more variance in regional sea surface temperatures than either proxy could explain alone. Just as importantly, networks of chronologies spanning multiple trophic levels can help identify climate variables critical to ecosystem functioning, which can then be targeted to generate most biologically relevant reconstructions possible. Along the west coast of North America, fish and bivalve chronologies in combination with records of seabird reproductive success indicate that winter sea-level pressure is closely associated with California Current productivity, which can be hind-cast over the past six centuries using coastal tree-ring chronologies. Thus, multiple proxies not only increase reconstruction skill, but also help isolate climate variables most closely linked to ecosystem structure and functioning.

Estimating daily climatologies for climate indices derived from climate model data and observations

Science.gov (United States)

Mahlstein, Irina; Spirig, Christoph; Liniger, Mark A; Appenzeller, Christof

2015-01-01

Climate indices help to describe the past, present, and the future climate. They are usually closer related to possible impacts and are therefore more illustrative to users than simple climate means. Indices are often based on daily data series and thresholds. It is shown that the percentile-based thresholds are sensitive to the method of computation, and so are the climatological daily mean and the daily standard deviation, which are used for bias corrections of daily climate model data. Sample size issues of either the observed reference period or the model data lead to uncertainties in these estimations. A large number of past ensemble seasonal forecasts, called hindcasts, is used to explore these sampling uncertainties and to compare two different approaches. Based on a perfect model approach it is shown that a fitting approach can improve substantially the estimates of daily climatologies of percentile-based thresholds over land areas, as well as the mean and the variability. These improvements are relevant for bias removal in long-range forecasts or predictions of climate indices based on percentile thresholds. But also for climate change studies, the method shows potential for use. Key Points More robust estimates of daily climate characteristics Statistical fitting approach Based on a perfect model approach PMID:26042192

Developing a National Climate Indicators System to Track Climate Changes, Impacts, Vulnerabilities, and Preparedness

Science.gov (United States)

Kenney, M. A.; Janetos, A. C.; Arndt, D.; Chen, R. S.; Pouyat, R.; Anderson, S. M.

2013-12-01

The National Climate Assessment (NCA) is being conducted under the auspices of the U.S. Global Change Research Program (USGCRP), pursuant to the Global Change Research Act of 1990, Section 106, which requires a report to Congress every 4 years. Part of the vision, which is now under development, for the sustained National Climate Assessment (NCA) process is a system of physical, ecological, and societal indicators that communicate key aspects of the physical climate, climate impacts, vulnerabilities, and preparedness for the purpose of informing both decision makers and the public with scientifically valid information that is useful to inform decision-making processes such as the development and implementation of climate adaptation strategies in a particular sector or region. These indicators will be tracked as a part of ongoing assessment activities, with adjustments as necessary to adapt to changing conditions and understanding. The indicators will be reviewed and updated so that the system adapts to new information. The NCA indicator system is not intended to serve as a vehicle for documenting rigorous cause and effect relationships. It is reasonable, however, for it to serve as a guide to those factors that affect the evolution of variability and change in the climate system, the resources and sectors of concern that are affected by it, and how society chooses to respond. Different components of the end-to-end climate issue serve as categories within which to organize an end-to-end system of indicators: Greenhouse Gas Emissions and Sinks, Atmospheric Composition, Physical Climate Variability and Change, Sectors and Resources of Concern, and Adaptation and Mitigation Responses. This framing has several advantages. It can be used to identify the different components of the end-to-end climate issue that both decision-makers and researchers are interested in. It is independent of scale, and therefore allows the indicators themselves to be described at spatial

The triple oxygen isotope composition of phytoliths as a proxy of continental atmospheric humidity: insights from climate chamber and climate transect calibrations

Directory of Open Access Journals (Sweden)

A. Alexandre

2018-05-01

Full Text Available Continental atmospheric relative humidity (RH is a key climate parameter. Combined with atmospheric temperature, it allows us to estimate the concentration of atmospheric water vapor, which is one of the main components of the global water cycle and the most important gas contributing to the natural greenhouse effect. However, there is a lack of proxies suitable for reconstructing, in a quantitative way, past changes of continental atmospheric humidity. This reduces the possibility of making model–data comparisons necessary for the implementation of climate models. Over the past 10 years, analytical developments have enabled a few laboratories to reach sufficient precision for measuring the triple oxygen isotopes, expressed by the 17O-excess (17O-excess  =  ln (δ17O + 1 – 0.528  ×  ln (δ18O + 1, in water, water vapor and minerals. The 17O-excess represents an alternative to deuterium-excess for investigating relative humidity conditions that prevail during water evaporation. Phytoliths are micrometric amorphous silica particles that form continuously in living plants. Phytolith morphological assemblages from soils and sediments are commonly used as past vegetation and hydrous stress indicators. In the present study, we examine whether changes in atmospheric RH imprint the 17O-excess of phytoliths in a measurable way and whether this imprint offers a potential for reconstructing past RH. For that purpose, we first monitored the 17O-excess evolution of soil water, grass leaf water and grass phytoliths in response to changes in RH (from 40 to 100 % in a growth chamber experiment where transpiration reached a steady state. Decreasing RH from 80 to 40 % decreases the 17O-excess of phytoliths by 4.1 per meg/% as a result of kinetic fractionation of the leaf water subject to evaporation. In order to model with accuracy the triple oxygen isotope fractionation in play in plant water and in phytoliths we recommend direct and

Methodology for qualitative uncertainty assessment of climate impact indicators

Science.gov (United States)

Otto, Juliane; Keup-Thiel, Elke; Rechid, Diana; Hänsler, Andreas; Pfeifer, Susanne; Roth, Ellinor; Jacob, Daniela

2016-04-01

The FP7 project "Climate Information Portal for Copernicus" (CLIPC) is developing an integrated platform of climate data services to provide a single point of access for authoritative scientific information on climate change and climate change impacts. In this project, the Climate Service Center Germany (GERICS) has been in charge of the development of a methodology on how to assess the uncertainties related to climate impact indicators. Existing climate data portals mainly treat the uncertainties in two ways: Either they provide generic guidance and/or express with statistical measures the quantifiable fraction of the uncertainty. However, none of the climate data portals give the users a qualitative guidance how confident they can be in the validity of the displayed data. The need for such guidance was identified in CLIPC user consultations. Therefore, we aim to provide an uncertainty assessment that provides the users with climate impact indicator-specific guidance on the degree to which they can trust the outcome. We will present an approach that provides information on the importance of different sources of uncertainties associated with a specific climate impact indicator and how these sources affect the overall 'degree of confidence' of this respective indicator. To meet users requirements in the effective communication of uncertainties, their feedback has been involved during the development process of the methodology. Assessing and visualising the quantitative component of uncertainty is part of the qualitative guidance. As visual analysis method, we apply the Climate Signal Maps (Pfeifer et al. 2015), which highlight only those areas with robust climate change signals. Here, robustness is defined as a combination of model agreement and the significance of the individual model projections. Reference Pfeifer, S., Bülow, K., Gobiet, A., Hänsler, A., Mudelsee, M., Otto, J., Rechid, D., Teichmann, C. and Jacob, D.: Robustness of Ensemble Climate Projections

National, ready-to-use climate indicators calculation and dissemination

Science.gov (United States)

Desiato, F.; Fioravanti, G.; Fraschetti, P.; Perconti, W.; Toreti, A.

2010-09-01

In Italy, meteorological data necessary and useful for climate studies are collected, processed and archived by a wide range of national and regional institutions. As a result, the density of the stations, the length and frequency of the observations, the quality control procedures and the database structure vary from one dataset to the other. In order to maximize the use of those data for climate knowledge and climate change assessments, a computerized system for the collection, quality control, calculation, regular update and rapid dissemination of climate indicators (denominated SCIA) was developed. Along with the pieces of information provided by complete metadata, climate indicators consist of statistics (mean, extremes, date of occurrence, standard deviation) over ten-days, monthly and yearly time periods of meteorological variables, including temperature, precipitation, humidity, wind, water balance, evapotranspitaton, degree-days, cloud cover, sea level pressure, solar radiation. In addition, normal values over thirty-year reference climatological periods and yearly anomalies are calculated and made available. All climate indicators, as well as their time series at a single location or spatial distribution at a selected time, are available through a dedicated web site (www.scia.sinanet.apat.it). In addition, secondary products like high resolution temperature maps obtained by kriging spatial interpolation, are made available. Over the last three years, about 40000 visitors accessed to the SCIA web site, with an average of 45 visitors per day. Most frequent visitors belong to categories like universities and research institutes; private companies and general public are present as well. Apart from research purposes, climate indicators disseminated through SCIA may be used in several socio-economic sectors like energy consumption, water management, agriculture, tourism and health. With regards to our activity, we base on these indicators for the estimation of

Stable carbon isotope fractionation in pollen of Atlas cedar: first steps towards a new palaeoecological proxy for Northwest Africa

Science.gov (United States)

Bell, Benjamin; Fletcher, William; Ryan, Peter; Grant, Helen; Ilmen, Rachid

2016-04-01

Analysis of stable carbon isotopes can provide information on climate and the environmental conditions at different growth stages of the plant, both past and present. Carbon isotope discrimination in plant tissue is already well understood, and can be used as a drought stress indicator for semi-arid regions. Stable carbon isotope ratios measured directly on pollen provides the potential for the development of long-term environmental proxies (spanning thousands of years), as pollen is well preserved in the environment. Atlas Cedar (Cedrus atlantica Endl. Manetti ex Carrière), is an ideal test case to develop a pollen stable carbon isotope proxy. The tree grows across a wide altitudinal and climatic range and is extremely sensitive to moisture availability. The pollen is abundant, and easily identifiable to the species level in pollen analysis because different cedar species are geographically confined to different regions of the world. In 2015 we sampled 76 individual cedar trees across latitudinal, altitudinal and environmental gradients, highly focused on the Middle Atlas region of Morocco, with 25 additional samples from botanical gardens across Europe and the US to extend these gradients. Here, we report new stable carbon isotope data from pollen, leaf and stem wood from these samples with a view to assessing and quantifying species-specific fractionation effects associated with pollen production. The isotopic response of individual trees at local and wider geographical scales to altitude and climatic conditions is presented. This research forms part of an ongoing PhD project working to develop and calibrate a modern carbon isotope proxy in Atlas cedar pollen, which can ultimately be applied to fossil sequences and complement existing multi-proxy records (e.g. pollen analysis in lake sediments, tree-rings).

Climate during the Roman and early-medieval periods in North-western Europe: a review of climate reconstructions from terrestrial archives

Science.gov (United States)

Reichelmann, Dana F. C.; Gouw-Bouman, Marjolein T. I. J.; Hoek, Wim Z.; van Lanen, Rowin J.; Stouthamer, Esther; Jansma, Esther

2016-04-01

High-resolution palaeoclimate reconstructions are essential to identify possible influences of climate variability on landscape evolution and landscape-related cultural changes (e.g., shifting settlement patterns and long-distance trade relations). North-western Europe is an ideal research area for comparison between climate variability and cultural transitions given its geomorphological diversity and the significant cultural changes that took place in this region during the last two millennia (e.g., the decline of the Roman Empire and the transition to medieval kingdoms). Compared to more global climate records, such as ice cores and marine sediments, terrestrial climate proxies have the advantage of representing a relatively short response time to regional climatic change. Furthermore for this region large quantity of climate reconstructions is available covering the last millennium, whereas for the first millennium AD only few high resolution climate reconstructions are available. We compiled climate reconstructions for sites in North-western Europe from the literature and its underlying data. All these reconstructions cover the time period of AD 1 to 1000. We only selected data with an annual to decadal resolution and a minimum resolution of 50 years. This resulted in 18 climate reconstructions from different archives such as chironomids (1), pollen (4), Sphagnum cellulose (1), stalagmites (6), testate amoebae (4), and tree-rings (2). The compilation of the different temperature reconstructions shows similar trends in most of the records. Colder conditions since AD 300 for a period of approximately 400 years and warmer conditions after AD 700 become apparent. A contradicting signal is found before AD 300 with warmer conditions indicated by most of the records but not all. This is likely the result of the use of different proxies, reflecting temperatures linked to different seasons. The compilation of the different precipitation reconstructions also show similar

A forward looking, actor based, indicator for climate gas emissions

Energy Technology Data Exchange (ETDEWEB)

Ericson, Torgeir; Randers, Joergen

2011-04-15

The most commonly used Norwegian indicator for climate change displays historical emissions and compare with Norway's Kyoto target. This indicator says little about future emissions, about the ongoing Norwegian effort to reduce climate gas emissions, or about its effect on sustainability. In this paper we propose an indicator that improves on these weaknesses. We present a forward looking climate indicator that in addition to historic data includes business as usual scenarios, different proposals for future domestic emissions, and national or international commitments and agreements. This indicator presents - in one graph - a broad diversity of views on how the climate challenge should be handled from now and into the future. This indicator-graph may contribute to a more transparent discussion of available policy options. (Author)

Physical, Ecological, and Societal Indicators for the National Climate Assessment

Science.gov (United States)

Kenney, Melissa A.; Chen, Robert; Baptista, Sandra R.; Quattrochi, Dale; O'Brien, Sheila

2011-01-01

The National Climate Assessment (NCA) is being conducted under the auspices of the U.S. Global Change Research Program (USGCRP), pursuant to the Global Change Research Act of 1990, Section 106, which requires a report to Congress every 4 years. The current NCA (http://globalchange.gov/what-we-do/assessment/) differs in multiple ways from previous U.S. climate assessment efforts, being: (1) more focused on supporting the Nation s activities in adaptation and mitigation and on evaluating the current state of scientific knowledge relative to climate impacts and trends; (2) a long-term, consistent process for evaluation of climate risks and opportunities and providing information to support decision-making processes within regions and sectors; and (3) establishing a permanent assessment capacity both inside and outside of the federal government. As a part of ongoing, long-term assessment activities, the NCA intends to develop an integrated strategic framework and deploy climate-relevant physical, ecological, and societal indicators. The NCA indicators framework is underdevelopment by the NCA Development and Advisory Committee Indicators Working Group and are envisioned as a relatively small number of policy-relevant integrated indicators designed to provide a consistent, objective, and transparent overview of major variations in climate impacts, vulnerabilities, adaptation, and mitigation activities across sectors, regions, and timeframes. The potential questions that could be addressed by these indicators include: How do we know that there is a changing climate and how is it expected to change in the future? Are important climate impacts and opportunities occurring or predicted to occur in the future? Are we adapting successfully? What are the vulnerabilities and resiliencies given a changing climate? Are we preparing adequately for extreme events? It is not expected that the NCA societal indicators would be linked directly to a single decision or portfolio of

Are optical indices good proxies of seasonal changes in carbon fluxes and stress-related physiological status in a beech forest?

Science.gov (United States)

Nestola, E; Scartazza, A; Di Baccio, D; Castagna, A; Ranieri, A; Cammarano, M; Mazzenga, F; Matteucci, G; Calfapietra, C

2018-01-15

This study investigates the functionality of a Mediterranean-mountain beech forest in Central Italy using simultaneous determinations of optical measurements, carbon (C) fluxes, leaf eco-physiological and biochemical traits during two growing seasons (2014-2015). Meteorological variables showed significant differences between the two growing seasons, highlighting a heat stress coupled with a reduced water availability in mid-summer 2015. As a result, a different C sink capacity of the forest was observed between the two years of study, due to the differences in stressful conditions and the related plant physiological status. Spectral indices related to vegetation (VIs, classified in structural, chlorophyll and carotenoid indices) were computed at top canopy level and used to track CO 2 fluxes and physiological changes. Optical indices related to structure (EVI 2, RDVI, DVI and MCARI 1) were found to better track Net Ecosystem Exchange (NEE) variations for 2014, while indices related to chlorophylls (SR red edge, CL red edge, MTCI and DR) provided better results for 2015. This suggests that when environmental conditions are not limiting for forest sink capacity, structural parameters are more strictly connected to C uptake, while under stress conditions indices related to functional features (e.g., chlorophyll content) become more relevant. Chlorophyll indices calculated with red edge bands (SR red edge, NDVI red edge, DR, CL red edge) resulted to be highly correlated with leaf nitrogen content (R 2 >0.70), while weaker, although significant, correlations were found with chlorophyll content. Carotenoid indices (PRI and PSRI) were strongly correlated with both chlorophylls and carotenoids content, suggesting that these indices are good proxies of the shifting pigment composition related to changes in soil moisture, heat stress and senescence. Our work suggests the importance of integrating different methods as a successful approach to understand how changing climatic

A statistical-dynamical modeling approach for the simulation of local paleo proxy records using GCM output

Energy Technology Data Exchange (ETDEWEB)

Reichert, B.K.; Bengtsson, L. [Max-Planck-Institut fuer Meteorologie, Hamburg (Germany); Aakesson, O. [Sveriges Meteorologiska och Hydrologiska Inst., Norrkoeping (Sweden)

1998-08-01

Recent proxy data obtained from ice core measurements, dendrochronology and valley glaciers provide important information on the evolution of the regional or local climate. General circulation models integrated over a long period of time could help to understand the (external and internal) forcing mechanisms of natural climate variability. For a systematic interpretation of in situ paleo proxy records, a combined method of dynamical and statistical modeling is proposed. Local 'paleo records' can be simulated from GCM output by first undertaking a model-consistent statistical downscaling and then using a process-based forward modeling approach to obtain the behavior of valley glaciers and the growth of trees under specific conditions. The simulated records can be compared to actual proxy records in order to investigate whether e.g. the response of glaciers to climatic change can be reproduced by models and to what extent climate variability obtained from proxy records (with the main focus on the last millennium) can be represented. For statistical downscaling to local weather conditions, a multiple linear forward regression model is used. Daily sets of observed weather station data and various large-scale predictors at 7 pressure levels obtained from ECMWF reanalyses are used for development of the model. Daily data give the closest and most robust relationships due to the strong dependence on individual synoptic-scale patterns. For some local variables, the performance of the model can be further increased by developing seasonal specific statistical relationships. The model is validated using both independent and restricted predictor data sets. The model is applied to a long integration of a mixed layer GCM experiment simulating pre-industrial climate variability. The dynamical-statistical local GCM output within a region around Nigardsbreen glacier, Norway is compared to nearby observed station data for the period 1868-1993. Patterns of observed

Environmental health indicators of climate change for the United States: findings from the State Environmental Health Indicator Collaborative.

Science.gov (United States)

English, Paul B; Sinclair, Amber H; Ross, Zev; Anderson, Henry; Boothe, Vicki; Davis, Christine; Ebi, Kristie; Kagey, Betsy; Malecki, Kristen; Shultz, Rebecca; Simms, Erin

2009-11-01

To develop public health adaptation strategies and to project the impacts of climate change on human health, indicators of vulnerability and preparedness along with accurate surveillance data on climate-sensitive health outcomes are needed. We researched and developed environmental health indicators for inputs into human health vulnerability assessments for climate change and to propose public health preventative actions. We conducted a review of the scientific literature to identify outcomes and actions that were related to climate change. Data sources included governmental and nongovernmental agencies and the published literature. Sources were identified and assessed for completeness, usability, and accuracy. Priority was then given to identifying longitudinal data sets that were applicable at the state and community level. We present a list of surveillance indicators for practitioners and policy makers that include climate-sensitive health outcomes and environmental and vulnerability indicators, as well as mitigation, adaptation, and policy indicators of climate change. A review of environmental health indicators for climate change shows that data exist for many of these measures, but more evaluation of their sensitivity and usefulness is needed. Further attention is necessary to increase data quality and availability and to develop new surveillance databases, especially for climate-sensitive morbidity.

Wildlife as biological indicators for assessing impacts of climate change

International Nuclear Information System (INIS)

Diamond, A.W.

1990-01-01

Estimates of the impacts of climate change on wildlife are necessarily constrained by knowledge of the effects of climate on wildlife. A review is presented of the better-known impacts of climate on wildlife, examining their utility as ecological indicators. The most obvious feature of any species is its geographic distribution, or range. Climate may affect distribution indirectly through effects on habitat, directly through physiological effects, or most probably, through both. Impacts can include changes in distribution of habitat, changes in distribution of species, and changes in migration routes. Direct effects of climate include timing and success of breeding, timing and success of migration, winter survival, and extreme events. Distribution changes are powerful integrators of ecosystem-level events, but poor indicators of particular changes. Changes in the timing of migration, and the phenology of breeding, are more directly determined by weather events and hence will be better indicators of changing climate. Detailed knowledge of effects of climate on timing and success of breeding is available for only a few species, and has not been carefully synthesized with a view to using such variables as climatic indicators. Temperature maxima and minima, frost-free and degree days, and estimates of precipitation on finer scales, both temporal and geographic, are needed to predict the effects of climate change on wildlife. 48 refs

A Kantian approach to a sustainable development indicator for climate

Energy Technology Data Exchange (ETDEWEB)

Greaker, Mads; Stoknes, Per Espen; Alfsen, Knut H.; Ericson, Torgeir

2012-11-01

How can the informed citizen know if the government is implementing a good-enough climate change policy? Most developed democracies have their own set of indicators for sustainable development, including indicators for climate change. These include yearly national emissions of greenhouse gasses (GHGs), global concentration of GHGs in the atmosphere and time series for global temperatures. However, without some kind of benchmark neither national emissions of GHGs nor global concentration of GHGs or temperatures, make it possible for the general public to evaluate the current climate policy of a nation state. In this paper we propose a benchmark for national climate policy based on a remaining Co2 budget allocated by egalitarian principles. Moreover, based on Kantian ethics we argue that this benchmark should be used as a sustainable development indicator for climate change. One way of interpreting Kantian ethics is to demand that each nation state should act as if a just global treaty on climate change were in place. We discuss possible important elements in a global treaty, and show how the different elements can be integrated in a forward-looking indicator of national climate policy.(auth)

Exploring Connections between Global Climate Indices and African Vegetation Phenology

Science.gov (United States)

Brown, Molly E.; deBeurs, Kirsten; Vrieling, Anton

2009-01-01

Variations in agricultural production due to rainfall and temperature fluctuations are a primary cause of food insecurity on the continent in Africa. Agriculturally destructive droughts and floods are monitored from space using satellite remote sensing by organizations seeking to provide quantitative and predictive information about food security crises. Better knowledge on the relation between climate indices and food production may increase the use of these indices in famine early warning systems and climate outlook forums on the continent. Here we explore the relationship between phenology metrics derived from the 26 year AVHRR NDVI record and the North Atlantic Oscillation index (NAO), the Indian Ocean Dipole (IOD), the Pacific Decadal Oscillation (PDO), the Multivariate ENSO Index (MEI) and the Southern Oscillation Index (SOI). We explore spatial relationships between growing conditions as measured by the NDVI and the five climate indices in Eastern, Western and Southern Africa to determine the regions and periods when they have a significant impact. The focus is to provide a clear indication as to which climate index has the most impact on the three regions during the past quarter century. We found that the start of season and cumulative NDVI were significantly affected by variations in the climate indices. The particular climate index and the timing showing highest correlation depended heavily on the region examined. The research shows that climate indices can contribute to understanding growing season variability in Eastern, Western and Southern Africa.

Appraising timing response of paleoenvironmental proxies to the Bond cycle in the western Mediterranean over the last 20 kyr

Science.gov (United States)

Rodrigo-Gámiz, Marta; Martínez-Ruiz, Francisca; Rodríguez-Tovar, Francisco J.; Pardo-Igúzquiza, Eulogio; Ortega-Huertas, Miguel

2018-04-01

The timing of climate responses to the Bond cycle is investigated in the western Mediterranean. Periodicities had been previously reported in a marine sediment record from this region spanning the last 20 kyr, and registered by diverse paleoenvironmental proxies, in particular those associated with terrigenous input, redox conditions, productivity, sea surface temperature (SST) and salinity. Further cross-spectral analyses on these time series reveal leads-lags in the 1400 year climate cycle. Considering as reference a terrigenous input proxy (the K/Al ratio), all the paleoenvironmental proxies displayed time shifts varying from ca. 700 year to ca. 350 year. SST and salinity variations show a first leaded response with the inflow of cold and less salty Atlantic waters. Followed by a time lead of 525 year, progresively arid conditions with an increase of eolian dust transport to the area, given by the Zr/Al signal, are observed. The intensification of dust transport could have triggered a latest biological response, lead by 350 year, with an increase of productivity, as suggested by the Ba/Al ratio. Lastly changes in the Mediterranean thermohaline circulation, indicated by a selected redox proxy (the U/Th ratio), are observed. These results support that the oceanic response triggered the atmospheric response to the Bond cycle in the western Mediterranean. Changes in the North Atlantic Oscillation mode and in the Inter-Tropical Convergence Zone migrations with variations in the monsoon activity or Saharan winds system, are considered as main forcing mechanisms, with a complex relationship of the involved phenomena.

Long memory effect of past climate change in Vostok ice core records

International Nuclear Information System (INIS)

Yamamoto, Yuuki; Kitahara, Naoki; Kano, Makoto

2012-01-01

Time series analysis of Vostok ice core data has been done for understanding of palaeoclimate change from a stochastic perspective. The Vostok ice core is one of the proxy data for palaeoclimate in which local temperature and precipitation rate, moisture source conditions, wind strength and aerosol fluxes of marine, volcanic, terrestrial, cosmogenic and anthropogenic origin are indirectly stored. Palaeoclimate data has a periodic feature and a stochastic feature. For the proxy data, spectrum analysis and detrended fluctuation analysis (DFA) were conducted to characterize periodicity and scaling property (long memory effect) in the climate change. The result of spectrum analysis indicates there exist periodicities corresponding to the Milankovitch cycle in past climate change occurred. DFA clarified time variability of scaling exponents (Hurst exponent) is associated with abrupt warming in past climate.

Atmospheric multidecadal variations in the North Atlantic realm: proxy data, observations, and atmospheric circulation model studies

Directory of Open Access Journals (Sweden)

K. Grosfeld

2007-01-01

Full Text Available We investigate the spatial and temporal characteristics of multidecadal climate variability in the North Atlantic realm, using observational data, proxy data and model results. The dominant pattern of multidecadal variability of SST depicts a monopolar structure in the North Atlantic during the instrumental period with cold (warm phases during 1900–1925 and 1970–1990 (1870–1890 and 1940–1960. Two atmospheric general circulation models of different complexity forced with global SST over the last century show SLP anomaly patterns from the warm and cold phases of the North Atlantic similar to the corresponding observed patterns. The analysis of a sediment core from Cariaco Basin, a coral record from the northern Red Sea, and a long-term sea level pressure (SLP reconstruction reveals that the multidecadal mode of the atmospheric circulation characterizes climate variability also in the pre-industrial era. The analyses of SLP reconstruction and proxy data depict a persistent atmospheric mode at least over the last 300 years, where SLP shows a dipolar structure in response to monopolar North Atlantic SST, in a similar way as the models' responses do. The combined analysis of observational and proxy data with model experiments provides an understanding of multidecadal climate modes during the late Holocene. The related patterns are useful for the interpretation of proxy data in the North Atlantic realm.

Advancements in the use of speleothems as climate archives

Science.gov (United States)

Wong, Corinne I.; Breecker, Daniel O.

2015-11-01

Speleothems have become a cornerstone of the approach to better understanding Earth's climatic teleconnections due to their precise absolute chronologies, their continuous or semicontinuous deposition and their global terrestrial distribution. We review the last decade of speleothem-related research, building off a similar review by McDermott (2004), in three themes - i) investigation of global teleconnections using speleothem-based climate reconstructions, ii) refinement of climate interpretations from speleothem proxies through cave monitoring, and iii) novel, technical methods of speleothem-based climate reconstructions. Speleothem records have enabled critical insight into the response of global hydroclimate to large climate changes. This includes the relevant forcings and sequence of climatic responses involved in glacial terminations and recognition of a global monsoon response to climate changes on orbital and millennial time scales. We review advancements in understanding of the processes that control speleothem δ13C values and introduce the idea of a direct atmospheric pCO2 influence. We discuss progress in understanding kinetic isotope fractionation, which, with further advances, may help quantify paleoclimate changes despite non-equilibrium formation of speleothems. This feeds into the potential of proxy system modeling to consider climatic, hydrological and biogeochemical processes with the objective of quantitatively interpreting speleothem proxies. Finally, we provide an overview of emerging speleothem proxies and novel approaches using existing proxies. Most recently, technical advancements made in the measurement of fluid inclusions are now yielding reliable determinations of paleotemperatures.

Holocene climatic fluctuations and periodic changes in the Asian southwest monsoon region

Science.gov (United States)

Zhang, Wenxiang; Niu, Jie; Ming, Qingzhong; Shi, Zhengtao; Lei, Guoliang; Huang, Linpei; Long, Xian'e.; Chang, Fengqin

2018-05-01

Climatic changes in the Asian southwest monsoon (ASWM) during the Holocene have become a topic of recent studies. It is important to understand the patterns and causes of Holocene climatic changes and their relationship with global changes. Based on the climate proxies and wavelet analysis of Lugu Lake in the ASWM region, the climatic fluctuations and periodic changes in the ASWM region during the Holocene have been reconstructed with a high-precision chronology. The results indicate the intensification of ASWM began to increase with Northern Hemisphere low-latitude solar insolation (LSI) and solar activity during the early Holocene, and gradually decreased during the late Holocene, exhibiting an apparent synchrony with numerous records of ASWM region. Meanwhile, an apparent 1000-a quasi-periodic signal is present in the environment proxies, and it demonstrates that the environmental change in the ASWM region has been driven mainly by LSI and solar activity.

Synchronous multi-decadal climate variability of the whole Pacific areas revealed in tree rings since 1567

Science.gov (United States)

Fang, Keyan; Cook, Edward; Guo, Zhengtang; Chen, Deliang; Ou, Tinghai; Zhao, Yan

2018-02-01

Oceanic and atmospheric patterns play a crucial role in modulating climate variability from interannual to multi-decadal timescales by causing large-scale co-varying climate changes. The brevity of the existing instrumental records hinders the ability to recognize climate patterns before the industrial era, which can be alleviated using proxies. Unfortunately, proxy based reconstructions of oceanic and atmospheric modes of the past millennia often have modest agreements with each other before the instrumental period, raising questions about the robustness of the reconstructions. To ensure the stability of climate signals in proxy data through time, we first identified tree-ring datasets from distant regions containing coherent variations in Asia and North America, and then interpreted their climate information. We found that the multi-decadal covarying climate patterns of the middle and high latitudinal regions around the northern Pacific Ocean agreed quite well with the climate reconstructions of the tropical and southern Pacific areas. This indicates a synchronous variability at the multi-decadal timescale of the past 430 years for the entire Pacific Ocean. This pattern is closely linked to the dominant mode of the Pacific sea surface temperature (SST) after removing the warming trend. This Pacific multi-decadal SST variability resembles the Interdecadal Pacific Oscillation.

A Multi-Proxy Paradigm in the Pursuit of Ocean Paleoredox

Science.gov (United States)

Anbar, A. D.; Duan, Y.; Kendall, B.; Reinhard, C.; Severmann, S.; Lyons, T. W.

2011-12-01

The geologic record provides abundant evidence for variations in ocean oxygenation throughout Earth history. Expansion of ocean anoxic zones is expected in the future as a consequence of global climate change, with attendant effects on global nutrient inventories, carbon cycling and fluxes of trace greenhouse gases to the atmosphere. Therefore, studying ancient ocean redox variations not only teaches us about the history of the Earth system, but also provides insights into how the system may respond to analogous human perturbations. However, the extent, duration, causes, and consequences of most past variations are poorly understood. This problem motivates the development of paleoredox proxies, including novel stable isotope systems such as Mo, Fe, U and Tl. Experience with these emerging isotope systems demonstrates great promise but also many challenges. The Mo isotope system is illustrative. To first order, the geochemical cycling and isotope systematics of this element are straightforward, making it a useful proxy. However, critical unresolved issues include: (a) uncertainties in the ocean inputs through time; (b) ambiguities about fractionation mechanisms; (c) inadequate understanding of how modern analogs map to ancient systems. Similar challenges confront all the novel isotope systems. The way forward requires integration of multiple isotopic proxies, as well as information gleaned from careful analyses of element concentrations. For example, an episode of Mo enrichment in the 2.5 Ga Mt. McRae Shale is generally interpreted as resulting from buildup of Mo in seawater due to oxidative weathering. This enrichment is therefore thought to indicate a "whiff" of O2 in the environment prior to the Great Oxidation Event that began at 2.4 Ga. Molybdenum isotopes are consistent with this interpretation. However, Mo enrichment due to enhanced input from low-T hydrothermal sources in an anoxic regime cannot be completely excluded given the current state of knowledge of

Using paleoclimate proxy-data to select an optimal realisation in an ensemble of simulations of the past millennium.

NARCIS (Netherlands)

Goosse, H.; Renssen, H.; Timmermann, A.; Bradley, R.S.; Mann, M.E.

2006-01-01

We present and describe in detail the advantages and limitations of a technique that combines in an optimal way model results and proxy-data time series in order to obtain states of the climate system consistent with model physics, reconstruction of past radiative forcing and proxy records. To

Developing a System of National Climate Assessment Indicators to Track Climate Change Impacts, Vulnerabilities, and Preparedness

Science.gov (United States)

Janetos, A. C.; Kenney, M. A.; Chen, R. S.; Arndt, D.

2012-12-01

The National Climate Assessment (NCA) is being conducted under the auspices of the U.S. Global Change Research Program (USGCRP), pursuant to the Global Change Research Act of 1990, Section 106, which requires a report to Congress every 4 years (http://globalchange.gov/what-we-do/assessment/). Part of the vision for the sustained National Climate Assessment (NCA) process is a system of physical, ecological, and societal indicators that communicate key aspects of the physical climate, climate impacts, vulnerabilities, and preparedness for the purpose of informing both decision makers and the public with scientifically valid information that is useful to inform decision-making processes such as the development and implementation of climate adaptation strategies in a particular sector or region. These indicators will be tracked as a part of ongoing assessment activities, with adjustments as necessary to adapt to changing conditions and understanding. The indicators will be reviewed and updated so that the system adapts to new information. The NCA indicator system is not intended to serve as a vehicle for documenting rigorous cause and effect relationships. It is reasonable, however, for it to serve as a guide to those factors that affect the evolution of variability and change in the climate system, the resources and sectors of concern that are affected by it, and how society chooses to respond. Different components of the end-to-end climate issue serve as categories within which to organize an end-to-end system of indicators: Greenhouse Gas Emissions and Sinks Atmospheric Composition Physical Climate Variability and Change Sectors and Resources of Concern Adaptation and Mitigation Responses This framing has several advantages. It can be used to identify the different components of the end-to-end climate issue that both decision-makers and researchers are interested in. It is independent of scale, and therefore allows the indicators themselves to be described at

Sensitivity of health sector indicators' response to climate change in Ghana.

Science.gov (United States)

Dovie, Delali B K; Dzodzomenyo, Mawuli; Ogunseitan, Oladele A

2017-01-01

There is accumulating evidence that the emerging burden of global climate change threatens the fidelity of routine indicators for disease detection and management of risks to public health. The threat partially reflects the conservative character of the health sector and the reluctance to adopt new indicators, despite the growing awareness that existing environmental health indicators were developed to respond to risks that may no longer be relevant, and are too simplistic to also act as indicators for newer global-scale risk factors. This study sought to understand the scope of existing health indicators, while aiming to discover new indicators for building resilience against three climate sensitive diseases (cerebro spinal meningitis, malaria and diarrhea). Therefore, new potential indicators derived from human and biophysical origins were developed to complement existing health indicators, thereby creating climate-sensitive battery of robust composite indices of resilience in health planning. Using Ghana's health sector as a case study systematic international literature review, national expert consultation, and focus group outcomes yielded insights into the relevance, sensitivity and impacts of 45 indicators in 11 categories in responding to climate change. In total, 65% of the indicators were sensitive to health impacts of climate change; 24% acted directly; 31% synergistically; and 45% indirectly, with indicator relevance strongly associated with type of health response. Epidemiological indicators (e.g. morbidity) and health demographic indicators (e.g. population structure) require adjustments with external indicators (e.g. biophysical, policy) to be resilient to climate change. Therefore, selective integration of social and ecological indicators with existing public health indicators improves the fidelity of the health sector to adopt more robust planning of interdependent systems to build resilience. The study highlights growing uncertainties in

Mobile phone call data as a regional socio-economic proxy indicator.

Directory of Open Access Journals (Sweden)

Sanja Šćepanović

Full Text Available The advent of publishing anonymized call detail records opens the door for temporal and spatial human dynamics studies. Such studies, besides being useful for creating universal models for mobility patterns, could be also used for creating new socio-economic proxy indicators that will not rely only on the local or state institutions. In this paper, from the frequency of calls at different times of the day, in different small regional units (sub-prefectures in Côte d'Ivoire, we infer users' home and work sub-prefectures. This division of users enables us to analyze different mobility and calling patterns for the different regions. We then compare how those patterns correlate to the data from other sources, such as: news for particular events in the given period, census data, economic activity, poverty index, power plants and energy grid data. Our results show high correlation in many of the cases revealing the diversity of socio-economic insights that can be inferred using only mobile phone call data. The methods and the results may be particularly relevant to policy-makers engaged in poverty reduction initiatives as they can provide an affordable tool in the context of resource-constrained developing economies, such as Côte d'Ivoire's.

Developing Health-Related Indicators of Climate Change: Australian Stakeholder Perspectives.

Science.gov (United States)

Navi, Maryam; Hansen, Alana; Nitschke, Monika; Hanson-Easey, Scott; Pisaniello, Dino

2017-05-22

Climate-related health indicators are potentially useful for tracking and predicting the adverse public health effects of climate change, identifying vulnerable populations, and monitoring interventions. However, there is a need to understand stakeholders' perspectives on the identification, development, and utility of such indicators. A qualitative approach was used, comprising semi-structured interviews with key informants and service providers from government and non-government stakeholder organizations in South Australia. Stakeholders saw a need for indicators that could enable the monitoring of health impacts and time trends, vulnerability to climate change, and those which could also be used as communication tools. Four key criteria for utility were identified, namely robust and credible indicators, specificity, data availability, and being able to be spatially represented. The variability of risk factors in different regions, lack of resources, and data and methodological issues were identified as the main barriers to indicator development. This study demonstrates a high level of stakeholder awareness of the health impacts of climate change, and the need for indicators that can inform policy makers regarding interventions.

Detecting the Spectrum of the Atlantic's Thermo-haline Circulation: Deconvolved Climate Proxies Show How Polar Climates Communicate

Science.gov (United States)

Reischmann, Elizabeth; Yang, Xiao; Rial, José

2014-05-01

Deconvolution is widely used in a wide variety of scientific fields, including its significant use in seismology, as a tool to recover real input from a system's impulse response and output. Our research uses spectral division deconvolution in the context of studying the impulse response of the possible relationship between the nonlinear climates of the Polar Regions by using select δ18O ice cores from both poles. This is feasible in spite of the fact that the records may be the result of nonlinear processes because the two polar climates are synchronized for the period studied, forming a Hilbert transform pair. In order to perform this analysis, the age models of three Greenland and four Antarctica records have been matched using a Monte Carlo method with the methane-matched pair GRIP and BYRD as a basis of calculations. For all of the twelve resulting pairs, various deconvolutions schemes (Weiner, Damped Least Squares, Tikhonov, Truncated Singular Value Decomposition) give consistent, quasi-periodic, impulse responses of the system. Multitaper analysis then demonstrates strong, millennia scale, quasi-periodic oscillations in these system responses with a range of 2,500 to 1,000 years. However, these results are directionally dependent, with the transfer function from north to south differing from that of south north. High amplitude power peaks at 5,000 to 1,7000 years characterize the former, while the latter contains peaks at 2,500 to 1,700 years. These predominant periodicities are also found in the data, some of which have been identified as solar forcing, but others of which may indicate internal oscillations of the climate system (1.6-1.4ky). The approximately 1,500 year period transfer function, which does not have a corresponding solar forcing, may indicate one of these internal periodicities of the system, perhaps even indicating the long-term presence of the Deep Water circulation, also known as the thermo-haline circulation (THC). Simplified models of

Millennial-scale climate variability recorded by gamma logging curve in Chaidam Basin

International Nuclear Information System (INIS)

Yuan Linwang; Chen Ye; Liu Zechun

2000-01-01

Using a natural gamma-ray logging curve of Dacan-1 core to inverse paleo-climate changes in Chaidam Basin, the process of environmental change of the past 150,000 years has been revealed. He in rich events and D-O cycles were identified, and can be matched well with those recorded in Greedland ice core. It suggests that the GR curve can identify tectonic and climatic events, is a sensitive proxy indicator of environmental and climatic changes

350 Year Cloud Reconstruction Deduced from Northeast Caribbean Coral Proxies

Science.gov (United States)

Winter, A.; Sammarco, P. W.; Mikolajewicz, U.; Jury, M.; Zanchettin, D.

2014-12-01

Clouds are a major factor influencing the global climate and its response to external forcing through their implications for the global hydrological cycle, and hence for the planetary radiative budget. Clouds also contribute to regional climates and their variability through, e.g., the changes they induce in regional precipitation patterns. There have been very few studies of decadal and longer-term changes in cloud cover in the tropics and sub-tropics, both over land and the ocean. In the tropics, there is great uncertainty regarding how global warming will affect cloud cover. Observational satellite data are too short to unambiguously discern any temporal trends in cloud cover. Corals generally live in well-mixed coastal regions and can often record environmental conditions of large areas of the upper ocean. This is particularly the case at low latitudes. Scleractinian corals are sessile, epibenthic fauna, and the type of environmental information recorded at the location where the coral has been living is dependent upon the species of coral considered and proxy index of interest. Skeletons of scleractinian corals are considered to provide among the best records of high-resolution (sub-annual) environmental variability in the tropical and sub-tropical oceans. Zooxanthellate hermatypic corals in tropical and sub-tropical seas precipitate CaCO3 skeletons as they grow. This growth is made possible through the manufacture of CaCO3crystals, facilitated by the zooxanthellae. During the process of crystallization, the holobiont binds carbon of different isotopes into the crystals. Stable carbon isotope concentrations vary with a variety of environmental conditions. In the Caribbean, d13C in corals of the species Montastraea faveolata can be used as a proxy for changes in cloud cover. In this contribution, we will demonstrate that the stable isotope 13C varies concomitantly with cloud cover for the northeastern Caribbean region. Using this proxy we have been able to

Growth rates and geochemical proxies in Late Campanian bivalves - New insights from micro-X-ray Fluorescence mapping and numerical growth modelling

Science.gov (United States)

de Winter, Niels; Goderis, Steven; van Malderen, Stijn; Vanhaecke, Frank; Claeys, Philippe

2017-04-01

Understanding the Late Cretaceous greenhouse climate is of vital importance for understanding present and future climate change. While a lot of good work has been done to reconstruct climate in this interesting period, most paleoclimatic studies have focused on long-term climate change[1]. Alternatively, multi-proxy records from marine bivalves provide us with a unique opportunity to study past climate on a seasonal scale. However, previous fossil bivalve studies have reported ambiguous results with regard to the interpretation of trace element and stable isotope proxies in marine bivalve shells[2]. One major problem in the interpretation of such records is the bivalve's vital effect and the occurrence of disequilibrium fractionation during bivalve growth. Both these problems are linked to the annual growth cycle of marine bivalves, which introduces internal effects on the incorporation of isotopes and trace elements into the shell[3]. Understanding this growth cycle in extinct bivalves is therefore of great importance for the interpretation of seasonal proxy records in their shells. In this study, three different species of extinct Late Campanian bivalves (two rudist species and one oyster species) that were found in the same stratigraphic interval are studied. Micro-X-Ray Fluorescence line scanning and mapping of trace elements such as Mg, Sr, S and Zn, calibrated by LA-ICP-MS measurements, is combined with microdrilled stable carbon and oxygen isotope analysis on the well-preserved part of the shells. Data of this multi-proxy study is compared with results from a numerical growth model written in the open-source statistics package R[4] and based on annual growth increments observed in the shells and shell thickness. This growth model is used together with proxy data to reconstruct rates of trace element incorporation into the shell and to calculate the mass balance of stable oxygen and carbon isotopes. In order to achieve this goal, 2D mapping of bivalve shell

Establishing a multi-proxy approach to alpine blockfield evolution in south-central Norway

Directory of Open Access Journals (Sweden)

Philipp Marr

2017-11-01

Full Text Available Blockfields in high latitude mountain areas are a wide spread proxy for glaciation history. Their origin is debated since decades, especially in south-central Norway, where glaciation had a major global climate implication. Some authors explain old blockfield features by protection of cold-based ice, others claim they persisted as nunataks during the LGM (~20 kyr, or were formed throughout the Holocene. In order to clarify the origin of alpine blockfields we established a multi-method approach to combining lichenometry, stratigraphy, granulometry, and geochemistry (XRD, XRF. Our lichenometric dating results in conjunction with our factors indicate landscape stability for at least ~12.5 kyr. Frequent climatic shifts are evident in our profiles by varying color, LOI content and grain sizes. On the basis of geochemical analyses we were able to identify a long-term (chemical weathering history and in situ blockfield formation. The field evidences and the climatic setting of the study area leave the possibility that our location was not covered by cold-based ice during the Late-Quaternary.

Climate and desertification: indicators for an assessment methodology

International Nuclear Information System (INIS)

Sciortino, M.; Caiaffa, E.; Fattoruso, G.; Donolo, R.; Salvetti, G.

2009-01-01

This work aims to define a methodology that, on the basis of commonly available surface climate records, assesses indicators of the increase or decrease of the extension of territories vulnerable to desertification and land degradation. The definition and quantification of environmental policy relevant indicators aims to improve the understanding and the decision making processes in dry lands. the results of this study show that since 1931 changes of climate involved 90% of the territory of the Sicilian region, with stronger intensity in the internal areas of Enna, Caltanissetta and Palermo provinces. (Author) 9 refs.

Late Quaternary Variability of Arctic Sea Ice: Insights From Biomarker Proxy Records and Model Simulations

Science.gov (United States)

Stein, R. H.; Fahl, K.; Gierz, P.; Niessen, F.; Lohmann, G.

2017-12-01

Over the last about four decades, coinciding with global warming and atmospheric CO2increase, the extent and thickness of Arctic sea ice has decreased dramatically, a decrease much more rapid than predicted by climate models. The driving forces of this change are still not fully understood. In this context, detailed paleoclimatic records going back beyond the timescale of direct observations, i.e., high-resolution Holocene records but also records representing more distant warm periods, may help to to distinguish and quantify more precisely the natural and anthropogenic greenhouse gas forcing of global climate change and related sea ice decrease. Here, we concentrate on sea ice biomarker records representing the penultimate glacial/last interglacial (MIS 6/MIS 5e) and the Holocene time intervals. Our proxy records are compared with climate model simulations using a coupled atmosphere-ocean general circulation model (AOGCM). Based on our data, polynya-type sea ice conditions probably occurred off the major ice sheets along the northern Barents and East Siberian continental margins during late MIS 6. Furthermore, we demonstrate that even during MIS 5e, i.e., a time interval when the high latitudes have been significantly warmer than today, sea ice existed in the central Arctic Ocean during summer, whereas sea ice was significantly reduced along the Barents Sea continental margin influenced by Atlantic Water inflow. Assuming a closed Bering Strait (no Pacific Water inflow) during early MIS 5, model simulations point to a significantly reduced sea ice cover in the central Arctic Ocean, a scenario that is however not supported by the proxy record and thus seems to be less realistic. Our Holocene biomarker proxy records from the Chukchi Sea indicate that main factors controlling the millennial Holocene variability in sea ice are probably changes in surface water and heat flow from the Pacific into the Arctic Ocean as well as the long-term decrease in summer insolation

Evaluation of proxy-based millennial reconstruction methods

Energy Technology Data Exchange (ETDEWEB)

Lee, Terry C.K.; Tsao, Min [University of Victoria, Department of Mathematics and Statistics, Victoria, BC (Canada); Zwiers, Francis W. [Environment Canada, Climate Research Division, Toronto, ON (Canada)

2008-08-15

A range of existing statistical approaches for reconstructing historical temperature variations from proxy data are compared using both climate model data and real-world paleoclimate proxy data. We also propose a new method for reconstruction that is based on a state-space time series model and Kalman filter algorithm. The state-space modelling approach and the recently developed RegEM method generally perform better than their competitors when reconstructing interannual variations in Northern Hemispheric mean surface air temperature. On the other hand, a variety of methods are seen to perform well when reconstructing surface air temperature variability on decadal time scales. An advantage of the new method is that it can incorporate additional, non-temperature, information into the reconstruction, such as the estimated response to external forcing, thereby permitting a simultaneous reconstruction and detection analysis as well as future projection. An application of these extensions is also demonstrated in the paper. (orig.)

Temperature variations in the southern Great Lakes during the last deglaciation: Comparison between pollen and GDGT proxies

Science.gov (United States)

Watson, Benjamin I.; Williams, John W.; Russell, James M.; Jackson, Stephen T.; Shane, Linda; Lowell, Thomas V.

2018-02-01

Our understanding of deglacial climate history in the southern Great Lakes region of the United States is primarily based upon fossil pollen data, with few independent and multi-proxy climate reconstructions. Here we introduce a new, well-dated fossil pollen record from Stotzel-Leis, OH, and a new deglacial temperature record based on branched glycerol dialkyl glycerol tetraethers (brGDGTs) at Silver Lake, OH. We compare these new data to previously published records and to a regional stack of pollen-based temperature reconstructions from Stotzel-Leis, Silver Lake, and three other well-dated sites. The new and previously published pollen records at Stotzel-Leis are similar, but our new age model brings vegetation events into closer alignment with known climatic events such as the Younger Dryas (YD). brGDGT-inferred temperatures correlate strongly with pollen-based regional temperature reconstructions, with the strongest correlation obtained for a global soil-based brGDGT calibration (r2 = 0.88), lending confidence to the deglacial reconstructions and the use of brGDGT and regional pollen stacks as paleotemperature proxies in eastern North America. However, individual pollen records show large differences in timing, rates, and amplitudes of inferred temperature change, indicating caution with paleoclimatic inferences based on single-site pollen records. From 16.0 to 10.0ka, both proxies indicate that regional temperatures rose by ∼10 °C, roughly double the ∼5 °C estimates for the Northern Hemisphere reported in prior syntheses. Change-point analysis of the pollen stack shows accelerated warming at 14.0 ± 1.2ka, cooling at 12.6 ± 0.4ka, and warming from 11.6 ± 0.5ka into the Holocene. The timing of Bølling-Allerød (B-A) warming and YD onset in our records lag by ∼300-500 years those reported in syntheses of temperature records from the northern mid-latitudes. This discrepancy is too large to be attributed to uncertainties in radiocarbon dating, and

Developing a proxy version of the Adult social care outcome toolkit (ASCOT).

Science.gov (United States)

Rand, Stacey; Caiels, James; Collins, Grace; Forder, Julien

2017-05-19

Social care-related quality of life is a key outcome indicator used in the evaluation of social care interventions and policy. It is not, however, always possible to collect quality of life data by self-report even with adaptations for people with cognitive or communication impairments. A new proxy-report version of the Adult Social Care Outcomes Toolkit (ASCOT) measure of social care-related quality of life was developed to address the issues of wider inclusion of people with cognitive or communication difficulties who may otherwise be systematically excluded. The development of the proxy-report ASCOT questionnaire was informed by literature review and earlier work that identified the key issues and challenges associated with proxy-reported outcomes. To evaluate the acceptability and content validity of the ASCOT-Proxy, qualitative cognitive interviews were conducted with unpaid carers or care workers of people with cognitive or communication impairments. The proxy respondents were invited to 'think aloud' while completing the questionnaire. Follow-up probes were asked to elicit further detail of the respondent's comprehension of the format, layout and content of each item and also how they weighed up the options to formulate a response. A total of 25 unpaid carers and care workers participated in three iterative rounds of cognitive interviews. The findings indicate that the items were well-understood and the concepts were consistent with the item definitions for the standard self-completion version of ASCOT with minor modifications to the draft ASCOT-Proxy. The ASCOT-Proxy allows respondents to rate the proxy-proxy and proxy-patient perspectives, which improved the acceptability of proxy report. A new proxy-report version of ASCOT was developed with evidence of its qualitative content validity and acceptability. The ASCOT-Proxy is ready for empirical testing of its suitability for data collection as a self-completion and/or interview questionnaire, and also

Ecoclimatic indicators to study crop suitability in present and future climatic conditions

Science.gov (United States)

Caubel, Julie; Garcia de Cortazar Atauri, Inaki; Huard, Frédéric; Launay, Marie; Ripoche, Dominique; Gouache, David; Bancal, Marie-Odile; Graux, Anne-Isabelle; De Noblet, Nathalie

2013-04-01

Climate change is expected to affect both regional and global food production through changes in overall agroclimatic conditions. It is therefore necessary to develop simple tools of crop suitability diagnosis in a given area so that stakeholders can envisage land use adaptations under climate change conditions. The most common way to investigate potential impacts of climate on the evolution of agrosystems is to make use of an array of agroclimatic indicators, which provide synthetic information derived from climatic variables and calculated within fixed periods (i.e. January first - 31th July). However, the information obtained during these periods does not enable to take account of the plant response to climate. In this work, we present some results of the research program ORACLE (Opportunities and Risks of Agrosystems & forests in response to CLimate, socio-economic and policy changEs in France (and Europe). We proposed a suite of relevant ecoclimatic indicators, based on temperature and rainfall, in order to evaluate crop suitability for both present and new climatic conditions. Ecoclimatic indicators are agroclimatic indicators (e.g., grain heat stress) calculated during specific phenological phases so as to take account of the plant response to climate (e.g., the grain filling period, flowering- harvest). These indicators are linked with the ecophysiological processes they characterize (for e.g., the grain filling). To represent this methodology, we studied the suitability of winter wheat in future climatic conditions through three distinct French sites, Toulouse, Dijon and Versailles. Indicators have been calculated using climatic data from 1950 to 2100 simulated by the global climate model ARPEGE forced by a greenhouse effect corresponding to the SRES A1B scenario. The Quantile-Quantile downscaling method was applied to obtain data for the three locations. Phenological stages (emergence, ear 1 cm, flowering, beginning of grain filling and harvest) have been

An indicator of the impact of climatic change on European bird populations.

Directory of Open Access Journals (Sweden)

Richard D Gregory

Full Text Available Rapid climatic change poses a threat to global biodiversity. There is extensive evidence that recent climatic change has affected animal and plant populations, but no indicators exist that summarise impacts over many species and large areas. We use data on long-term population trends of European birds to develop such an indicator. We find a significant relationship between interspecific variation in population trend and the change in potential range extent between the late 20(th and late 21(st centuries, forecasted by climatic envelope models. Our indicator measures divergence in population trend between bird species predicted by climatic envelope models to be favourably affected by climatic change and those adversely affected. The indicator shows a rapid increase in the past twenty years, coinciding with a period of rapid warming.

Climate indices of Iran under climate change

OpenAIRE

alireza kochaki; mehdi nasiry; gholamali kamali

2009-01-01

Global warming will affect all climatic variables and particularly rainfall patterns. The purpose of present investigation was to predict climatic parameters of Iran under future climate change and to compare them with the present conditions. For this reason, UKMO General Circulation Model was used for the year 2025 and 2050. By running the model, minimum and maximum monthly temperature and also maximum monthly rainfall for the representative climate stations were calculated and finally the e...

Methods for extracting climate indicator data from social media.

Science.gov (United States)

Fuka, M. Z.; Fuka, D. R.

2011-12-01

This paper shows how we've used the R software suite to extract climate indicator data from Twitter. In the course of this research we've collected extensive data sets of unsolicited observations ("tweets") for hundreds of climate-related phenological, biological, epidemiological and meteorological effects. R has proved itself in our work as a useful tool for manipulating those large data sets. Our experience from this effort has yielded a variety of insights on using R to extract geophysics-specific information from publicly accessible social media sources. We illustrate our methodology by mapping tweeted US armadillo sightings to explore the impact of climate variability on the extent of the animal's range. This example usefully demonstrates R's technical capabilities in collecting, time-stamping, geolocating, analyzing, visualizing and otherwise processing climate-related data derived from unsolicited social media postings. We also "mash-up" the data sets with those acquired by more traditional means, for example, temperature and precipitation data across the armadillo's US range. Our data-handling practice is extendable to social sharing services other than Twitter, providing the environmental modeling community an opportunity to access largely untapped resources of non-traditional climate indicator data to better understand the effects of climate change at local, regional and global scales.

Climate Reconstructions

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA Paleoclimatology Program archives reconstructions of past climatic conditions derived from paleoclimate proxies, in addition to the Program's large holdings...

Climate risk index for Italy

Science.gov (United States)

Mysiak, Jaroslav; Torresan, Silvia; Bosello, Francesco; Mistry, Malcolm; Amadio, Mattia; Marzi, Sepehr; Furlan, Elisa; Sperotto, Anna

2018-06-01

We describe a climate risk index that has been developed to inform national climate adaptation planning in Italy and that is further elaborated in this paper. The index supports national authorities in designing adaptation policies and plans, guides the initial problem formulation phase, and identifies administrative areas with higher propensity to being adversely affected by climate change. The index combines (i) climate change-amplified hazards; (ii) high-resolution indicators of exposure of chosen economic, social, natural and built- or manufactured capital (MC) assets and (iii) vulnerability, which comprises both present sensitivity to climate-induced hazards and adaptive capacity. We use standardized anomalies of selected extreme climate indices derived from high-resolution regional climate model simulations of the EURO-CORDEX initiative as proxies of climate change-altered weather and climate-related hazards. The exposure and sensitivity assessment is based on indicators of manufactured, natural, social and economic capital assets exposed to and adversely affected by climate-related hazards. The MC refers to material goods or fixed assets which support the production process (e.g. industrial machines and buildings); Natural Capital comprises natural resources and processes (renewable and non-renewable) producing goods and services for well-being; Social Capital (SC) addressed factors at the individual (people's health, knowledge, skills) and collective (institutional) level (e.g. families, communities, organizations and schools); and Economic Capital (EC) includes owned and traded goods and services. The results of the climate risk analysis are used to rank the subnational administrative and statistical units according to the climate risk challenges, and possibly for financial resource allocation for climate adaptation. This article is part of the theme issue `Advances in risk assessment for climate change adaptation policy'.

Climate changes over the past millennium: Relationships with Mediterranean climates

International Nuclear Information System (INIS)

Mann, M.E.

2006-01-01

Evidence is reviewed for climate change and its causes over the interval spanning roughly the past millennium. Particular emphasis is placed on patterns of climate change influencing Mediterranean climates of the Northern Hemisphere. The evidence is taken from studies using high-resolution climate proxy data sources, and climate modeling simulations. The available evidence suggests that forced changes in dynamical modes of variability including the North Atlantic Oscillation (NAO) and El Nino/Southern Oscillation (ENSO) have played a key role in the patterns of climate variability in Mediterranean regions over the past millennium

Drought forecasting in Luanhe River basin involving climatic indices

Science.gov (United States)

Ren, Weinan; Wang, Yixuan; Li, Jianzhu; Feng, Ping; Smith, Ronald J.

2017-11-01

Drought is regarded as one of the most severe natural disasters globally. This is especially the case in Tianjin City, Northern China, where drought can affect economic development and people's livelihoods. Drought forecasting, the basis of drought management, is an important mitigation strategy. In this paper, we evolve a probabilistic forecasting model, which forecasts transition probabilities from a current Standardized Precipitation Index (SPI) value to a future SPI class, based on conditional distribution of multivariate normal distribution to involve two large-scale climatic indices at the same time, and apply the forecasting model to 26 rain gauges in the Luanhe River basin in North China. The establishment of the model and the derivation of the SPI are based on the hypothesis of aggregated monthly precipitation that is normally distributed. Pearson correlation and Shapiro-Wilk normality tests are used to select appropriate SPI time scale and large-scale climatic indices. Findings indicated that longer-term aggregated monthly precipitation, in general, was more likely to be considered normally distributed and forecasting models should be applied to each gauge, respectively, rather than to the whole basin. Taking Liying Gauge as an example, we illustrate the impact of the SPI time scale and lead time on transition probabilities. Then, the controlled climatic indices of every gauge are selected by Pearson correlation test and the multivariate normality of SPI, corresponding climatic indices for current month and SPI 1, 2, and 3 months later are demonstrated using Shapiro-Wilk normality test. Subsequently, we illustrate the impact of large-scale oceanic-atmospheric circulation patterns on transition probabilities. Finally, we use a score method to evaluate and compare the performance of the three forecasting models and compare them with two traditional models which forecast transition probabilities from a current to a future SPI class. The results show that the

Greenhouse gas emissions considered responsible for climate change: Environmental indicators

International Nuclear Information System (INIS)

Vialetto, G.; Venanzi, M.; Gaudioso, D.

1993-09-01

This paper concerns the more significant environmental indicators related to the emissions of radiatively and chemically/photochemically active trace gases. Reference is made to the preliminary work of the Intergovernmental Panel on Climate Change (IPCC) and to the proposals made in the framework of the international negotiation on climate change. Aiming to contribute to the definition of a national strategy for the reduction of greenhouse gases emissions, this paper proposes a possible application of the indicators. The calculation of the indicators is based on the emission estimate performed by ENEA (Italian National Agency for Energy, New Technologies and the Environment) for the Report on the State of the Environment edited by the Italian Ministry of the Environment. Finally, the paper suggests an application of such indicators for the international negotiation, in the framework of the Italian proposal for the Convention on climate change

High-Arctic climate conditions for the last 7000 years inferred from multi-proxy analysis of the Bliss Lake record, North Greenland

DEFF Research Database (Denmark)

Olsen, Jesper; Kjær, Kurt H.; Funder, Svend Visby

2012-01-01

, Peary Land, Greenland. The early Holocene (10 850–10 480 cal. a BP) is characterized by increased erosion and gradually more marine conditions. Full marine conditions developed from 10 480 cal. a BP until the lake was isolated at 7220 cal. a BP. From its marine isolation at 7220 cal. a BP Bliss Lake...... becomes a lacustrine environment. Evidence from geochemical proxies (δ13C and total organic carbon) suggests that warmer conditions prevailed between 7220 and 6500 cal. a BP, corresponding to the Holocene thermal maximum, and from 3300 until 910 cal. a BP. From 850 to 500 cal. a BP colder climate...

Calibration and application of the branched GDGT proxy on East African lake sediments

NARCIS (Netherlands)

Loomis, S.E.; Russell, J.M.; Ladd, B.; Street-Perrott, F.A.; Sinninghe Damsté, J.S.

2012-01-01

Branched glycerol dialkyl glycerol tetraethers (brGDGTs) are a novel proxy for mean annual air temperature (MAAT) and have the potential to be broadly applicable to climate reconstruction using lacustrine sediments. Several calibrations have been put forth relating brGDGT distributions to MAAT using

Multi-proxy studies in palaeolimnology

OpenAIRE

Birks, Hilary H.; Birks, Harry John Betteley

2006-01-01

Multi-proxy studies are becoming increasingly common in palaeolimnology. Eight basic requirements and challenges for a multi-proxy study are outlined in this essay – definition of research questions, leadership, site selection and coring, data storage, chronology, presentation of results, numerical tools, and data interpretation. The nature of proxy data is discussed in terms of physical proxies and biotic proxies. Loss-on-ignition changes and the use of transfer functions are reviewed as exa...

Here be web proxies

DEFF Research Database (Denmark)

Weaver, Nicholas; Kreibich, Christian; Dam, Martin

2014-01-01

,000 clients that include a novel proxy location technique based on traceroutes of the responses to TCP connection establishment requests, which provides additional clues regarding the purpose of the identified web proxies. Overall, we see 14% of Netalyzr-analyzed clients with results that suggest the presence...... of web proxies....

Middle to Late Pleistocene multi-proxy record of environmental response to climate change from the Vienna Basin, Central Europe (Austria)

Science.gov (United States)

Salcher, Bernhard C.; Frank-Fellner, Christa; Lomax, Johanna; Preusser, Frank; Ottner, Franz; Scholger, Robert; Wagreich, Michael

2017-10-01

Tectonic basins can represent valuable archives of the environmental history. Presented here are the stratigraphy and multi-proxy analyses of two adjacent alluvial fans in the Quaternary active parts of the Vienna Basin, situated at the interface of the Atlantic, European continental and Mediterranean climate. Deposits comprise a sequence of coarse-grained fluvial deposits intercalated by laterally extensive horizons of pedogenically altered fine sediments. To establish palaeoenvironmental reconstructions, fine-grained sequences from a drill core and outcrop data were analysed according to its malacofauna, palaeopedology, susceptibility and sedimentology. The chronological framework is provided by 38 luminescence ages and supported by geomagnetic polarity investigations. Distinct warm periods each associated with a geomagnetic excursion, are recorded in three pedocomplexes formed during the Last Interglacial and two earlier interglacial periods, indicted to correlate with Marine Isotope Stage (MIS) 9 and MIS 11, respectively. Environmental conditions during the early last glacial period (MIS 5, c. 100-70 ka) are reconstructed from mollusc-shell rich overbank fines deposited along a former channel belt, covered by massive sheetflood deposits during MIS 2. Analysed warm phases suggest strong variations in humidity, ranging from steppe to forest dominated environments. The study presents one of the few numerically dated Middle Pleistocene multi-proxy records and one of the most comprehensive malacological datasets covering the early phases of last glacial period of continental Europe.

Jemen - the Proxy War

Directory of Open Access Journals (Sweden)

Magdalena El Ghamari

2015-12-01

Full Text Available The military operation in Yemen is significant departure from Saudi Arabia's foreign policy tradition and customs. Riyadh has always relied on three strategies to pursue its interests abroad: wealth, establish a global network and muslim education and diplomacy and meadiation. The term "proxy war" has experienced a new popularity in stories on the Middle East. A proxy war is two opposing countries avoiding direct war, and instead supporting combatants that serve their interests. In some occasions, one country is a direct combatant whilst the other supporting its enemy. Various news sources began using the term to describe the conflict in Yemen immediately, as if on cue, after Saudi Arabia launched its bombing campaign against Houthi targets in Yemen on 25 March 2015. This is the reason, why author try to answer for following questions: Is the Yemen Conflict Devolves into Proxy War? and Who's fighting whom in Yemen's proxy war?" Research area includes the problem of proxy war in the Middle East. For sure, the real problem of proxy war must begin with the fact that the United States and its NATO allies opened the floodgates for regional proxy wars by the two major wars for regime change: in Iraq and Libya. Those two destabilising wars provided opportunities and motives for Sunni states across the Middle East to pursue their own sectarian and political power objectives through "proxy war".

Spatial linkages between coral proxies of terrestrial runoff across a large embayment in Madagascar

NARCIS (Netherlands)

Grove, C.A.; Zinke, J.; Scheufen, T.; Maina, J.; Epping, E.; Boer, W.; Randriamanantsoa, B.; Brummer, G.-J.A.

2012-01-01

Coral cores provide vital climate reconstructions for site-specific temporal variability in river flow and sediment load. Yet, their ability to record spatial differences across multiple catchments is relatively unknown. Here, we investigate spatial linkages between four coral proxies of terrestrial

Millennial-scale climate variations in western Mediterranean during late Pleistocene-early Holocene: multi-proxy analyses from Padul peatbog (southern Iberian Peninsula)

Science.gov (United States)

Camuera, Jon; Jiménez-Moreno, Gonzalo; José Ramos-Román, María; García-Alix, Antonio; Jiménez-Espejo, Francisco; Toney, Jaime L.; Anderson, R. Scott; Kaufman, Darrell; Bright, Jordon; Sachse, Dirk

2017-04-01

Padul peatbog, located in southern Iberian Peninsula (western Mediterranean region) is a unique area for palaeoenvironmental studies due to its location, between arid and temperate climates. Previous studies showed that the Padul peatbog contains a continuous record of the last ca. 0.8-1 Ma, so it is an extraordinary site to identify glacial-interglacial phases as well as Heinrich and D-O events, linked to orbital- and suborbital-scale variations. In 2015, a new 42 m long core was taken from this area, providing an excellent sediment record probably for the last ca. 300,000 years. This study is focused on the paleoenvironmental and climatic reconstruction of the late Pleistocene and the early Holocene (ca. from 50,000 to 9,500 cal. yrs BP), using AMS 14C and AAR dating, high-resolution pollen analysis, lithology, continuous XRF-scanning, X-ray diffraction, magnetic susceptibility and organic geochemistry. These different proxies provide information not only about the regional environment change but also about local changes in the conditions of the Padul lake/peatbog due to variations in water temperature, pH or nutrients.

Assessment of weather indicators for possible climate change

International Nuclear Information System (INIS)

Maqssood, H.; Ahmed, S.I.

2014-01-01

From 20 century onwards, a great concern has been expressed regarding global climate change. This study attempts to perform detailed analysis of temperature and precipitation for Karachi city of Pakistan, to assess the possible climate change, using two data sets (51-year data: 1961-2012 and 31-year data: 1981-2012) for different parameters. Trends were generated using linear regression (LR) and Mann-Kendall (MK), which depicted that daily and annual temperatures were increasing, with changes in minimum temperature being more significant than maximum temperature. Analyses also showed increase in extreme temperature at night and during winter, showing that urbanization was a major factor, as the heat from buildings trapped in between dissipates at nights. The daily and monthly precipitation levels increased in contrast to annual precipitation trend, which is justified by the averaged monthly analysis showing that decreasing trends were much more significant than increasing trends. In addition, monthly precipitation showed an increase of 4.3 mm, using LR and MK test. It can be noticed that two extreme winter months (December and January) and two extreme hot months (May and October) received increased rainfall. However, statistical analyses showed overall annual decrease in rainfall. Furthermore, decadal analysis indicated sinusoidal behaviour of change in climate indicators; making climatic change evident but cyclic in nature. (author)

Using CAM3 and the Alkenone Method to Understand how Pliocene SST's Affect California and Other Climates Adjacent to Upwelling Regions

Science.gov (United States)

Searles, Z. A.; Otto-Bliesner, B. L.; Rosenbloom, N. A.; Dekens, P. S.

2008-12-01

The Intergovernmental Panel on Climate Change fourth assessment report established with 90% confidence that anthropogenic climate change will result in a warmer world. In order to more fully understand possible future climate, past analogues of warm periods should be analyzed. The early Pliocene is an appropriate analogue because the continental configuration was similar to today and CO2 levels were comparable to present (~100ppm higher than pre-anthropogenic levels). This project has two objectives: 1.To test the atmospheric sensitivity to USGS PRISM2 dataset revised to better approximate proxy data indicating warmer SST's in upwelling regions and 2. To provide early-Pliocene (2.7- 3.5 Ma) SST estimates for ODP site 1018 on the California Margin (36°59.4'N, 123°16.5'W) using the UK'37 SST proxy. Recent UK'37 proxy data reveals that PRISM2 underestimates SST's in Pacific and Atlantic coastal upwelling regions. The sensitivity of the atmosphere to significantly warmer SST's in upwelling regions was tested using the National Center for Atmospheric Research (NCAR) Community Atmospheric Model, version 3 (CAM3). Initial conditions were supplied by the USGS PRISM2 project and include Pliocene SST's, vegetation cover, sea level height, topography, marine and continental ice extent. Pliocene SST's along the Californian, Peruvian, North African and South African margin were modified to reflect proxy observations from 4 sites. The lack of observational coverage (1 data point per region) required interpolation of the areal extent of the SST warming anomaly indicated by the proxies. Experiment results show increased cumulative precipitation and humidity in regions where the original PRISM2 predicted drying. The predicted North American increase in precipitation is in better agreement with geologic proxies indicating wetter conditions. Warmer SST's also causes weaker wind velocities along the North American, Peruvian, and North African margins, and stronger winds along the

Climate at the edge of human dispersal in the European Middle Pleistocene

Science.gov (United States)

Horne, David

2014-05-01

Pleistocene palaeoclimatic reconstructions based on fossils from sites containing archaeological evidence of human occupation can answer key questions about the climatic context of early human dispersal in Europe. Biological proxies including foraminifera, ostracods, diatoms, chironomid larvae, molluscs and pollen are widely used to estimate palaeoclimatic parameters, typically palaeotemperatures, using indicator species, Mutual Climatic Range (MCR), Modern Analogue Technique (MAT) and transfer function approaches. Any single proxy method will yield plausible results, but there is a need for multi-proxy testing; matching or overlapping results inspire confidence, whereas if independent proxies yield results that do not match or even overlap, one or more must be wrong. The Multi-Proxy Consensus (MPC) approach not only compares two or more proxy results in order to check for agreement, but also offers potential for more refined results to be obtained from the range of mutual agreement between two or more overlapping palaeotemperature ranges. Studies of MIS9 (late Middle Pleistocene) deposits in the Thames-Medway river system in SE England (some of which contain stone implements representing human occupation) have yielded palaeotemperature estimates based on ostracods, beetles, fish, herpetiles, pollen and plant macrofossils. The MPC approach demonstrates the consistency of the results and defines a more continental climate than today (mean July air temperatures similar or 1 degree warmer, mean January air temperatures at least 2 degrees colder). Two River Thames MIS11 sites (Ebbsfleet and Swanscombe) have yielded MPC results indicating summers up to 1.5 degrees warmer and winters at least 5 degrees colder than today. British early Middle Pleistocene sites record the earliest human presence in Europe North of the Alps. At Boxgrove (MIS13), well-known for its rich record of human activity (stone tools and butchered bones), combined ostracod and herpetile MCR results

Collective behaviour of climate indices in the North Pacific air—sea system and its potential relationships with decadal climate changes

International Nuclear Information System (INIS)

Wang Xiao-Juan; Zhi Rong; He Wen-Ping; Gong Zhi-Qiang

2012-01-01

A climate network of six climate indices of the North Pacific air—sea system is constructed during the period of 1948–2009. In order to find out the inherent relationship between the intrinsic mechanism of climate index network and the important climate shift, the synchronization behaviour and the coupling behaviour of these indices are investigated. Results indicate that climate network synchronization happened around the beginning of the 1960s, in the middle of the 1970s and at the beginnings of the 1990s and the 2000s separately. These synchronization states were always followed by the decrease of the coupling coefficient. Each synchronization of the network was well associated with the abrupt phase or trend changes of annually accumulated abnormal values of North Pacific sea-surface temperature and 500-hPa height, among which the one that happened in the middle of the 1970s is the most noticeable climate shift. We can also obtain this mysterious shift from the first mode of the empirical orthogonal function of six indices. That is to say, abrupt climate shift in North Pacific air—sea system is not only shown by the phase or trend changes of climate indices, but also might be indicated by the synchronizing and the coupling of climate indices. Furthermore, at the turning point of 1975, there are also abrupt correlation changes in the yearly mode of spatial degree distribution of the sea surface temperature and 500-hPa height in the region of the North Pacific, which further proves the probability of climate index synchronization and coupling shift in air—sea systems. (geophysics, astronomy, and astrophysics)

Collective behaviour of climate indices in the North Pacific air-sea system and its potential relationships with decadal climate changes

Institute of Scientific and Technical Information of China (English)

Wang Xiao-Juan; Zhi Rong; He Wen-Ping; Gong Zhi-Qiang

2012-01-01

A climate network of six climate indices of the North Pacific air-sea system is constructed during the period of 1948-2009.In order to find out the inherent relationship between the intrinsic mechanism of climate index network and the important climate shift,the synchronization behaviour and the coupling behaviour of these indices are investigated.Results indicate that climate network synchronization happened around the beginning of the 1960s,in the middle of the 1970s and at the beginnings of the 1990s and the 2000s separately.These synchronization states were always followed by the decrease of the coupling coefficient.Each synchronization of the network was well associated with the abrupt phase or trend changes of annually accumulated abnormal vaiues of North Pacific sea-surface temperature and 500-hPa height,among which the one that happened in the middle of the 1970s is the most noticeable climate shift.We can also obtain this mysterious shift from the first mode of the empirical orthogonal function of six indices.That is to say,abrupt climate shift in North Pacific air-sea system is not only shown by the phase or trend changes of climate indices,but also night be indicated by the synchronizing and the coupling of climate indices.Furthermore,at the turning point of 1975,there are also abrupt correlation changes in the yearly mode of spatial degree distribution of the sea surface temperature and 500-hPa height in the region of the North Pacific,which further proves the probability of climate index synchronization and coupling shift in air-sea systems.

A multi-proxy perspective on millennium-long climate variability in the Southern Pyrenees

NARCIS (Netherlands)

Morellón, M.; Pérez-Sanz, A.; Corella, J.P.; Büntgen, U.; Catalán, J.; González-Samprizé, P.; González-Trueba, J.J.; López-Sáez, J.A.; Moreno, A.; Pla-Rabes, S.; Saz-Sánchez, M.Á.; Scussolini, P.; Serrano, E.; Steinhilber, F.; Stefanova, V.; Vegas-Vilarrúbia, T.; Valero-Garcés, B.

2012-01-01

This paper reviews multi-proxy paleoclimatic reconstructions with robust age-control derived from lacustrine, dendrochronological and geomorphological records and characterizes the main environmental changes that occurred in the Southern Pyrenees during the last millennium. Warmer and relatively

Climate Prediction Center (CPC) Palmer Drought and Crop Moisture Indices

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Climate Prediction Center (CPC) Palmer Drought Severity and Crop Moisture Indices are computed for the 344 U.S. Climate Divisions on a weekly basis based on a...

Impact of late glacial climate variations on stratification and trophic state of the meromictic lake Längsee (Austria: validation of a conceptual model by multi proxy studies

Directory of Open Access Journals (Sweden)

Jens MÜLLER

2002-02-01

Full Text Available Selected pigments, diatoms and diatom-inferred phosphorus (Di-TP concentrations of a late glacial sediment core section of the meromictic Längsee, Austria, were compared with tephra- and varve-dated pollen stratigraphic and geochemical results. A conceptual model was adopted for Längsee and evaluated using multi proxy data. During the unforested late Pleniglacial, a holomictic lake stage with low primary productivity prevailed. Subsequent to the Lateglacial Betula expansion, at about 14,300 cal. y BP, okenone and isorenieratene, pigments from purple and green sulphur bacteria, indicate the onset of anoxic conditions in the hypolimnion. The formation of laminae coincides with this anoxic, meromictic period with high, though fluctuating, amounts of okenone that persisted throughout the Lateglacial interstadial. The occurrence of unlaminated sediment sections of allochthonous origin, and concurrent low concentrations of okenone, were related to cool and wet climate fluctuations during this period, probably coupled with a complete mixing of the water column. Two of these oscillations of the Lateglacial interstadial have been correlated tentatively with the Aegelsee and Gerzensee oscillations in the Alps. The latter climate fluctuation divides a period of enhanced anoxia and primary productivity, correlated with the Alleröd chronozone. Continental climate conditions were assumed to be the main driving forces for meromictic stability during Alleröd times. In addition, calcite dissolution due to severe hypolimnetic anoxia, appear to have supported meromictic stability. Increased pigment concentrations, which are in contrast to low diatom-inferred total phosphorus (Di- TP, indicate the formation of a productive metalimnion during this period, probably due to a clear-water phase (low catchment erosion, increased temperatures, and a steep gradient between the phosphorus enriched hypolimnion and the oligotrophic epilimnion. Meltwater impacts from an

Temperature variations in the southern Great Lakes during the last deglaciation: Comparison between pollen and GDGT proxies

Science.gov (United States)

Watson, Benjamin I.; Williams, John W.; Russell, James M.; Jackson, Stephen T.; Shane, Linda; Lowell, Thomas V.

2018-01-01

Our understanding of deglacial climate history in the southern Great Lakes region of the United States is primarily based upon fossil pollen data, with few independent and multi-proxy climate reconstructions. Here we introduce a new, well-dated fossil pollen record from Stotzel-Leis, OH, and a new deglacial temperature record based on branched glycerol dialkyl glycerol tetraethers (brGDGTs) at Silver Lake, OH. We compare these new data to previously published records and to a regional stack of pollen-based temperature reconstructions from Stotzel-Leis, Silver Lake, and three other well-dated sites. The new and previously published pollen records at Stotzel-Leis are similar, but our new age model brings vegetation events into closer alignment with known climatic events such as the Younger Dryas (YD). brGDGT-inferred temperatures correlate strongly with pollen-based regional temperature reconstructions, with the strongest correlation obtained for a global soil-based brGDGT calibration (r2 = 0.88), lending confidence to the deglacial reconstructions and the use of brGDGT and regional pollen stacks as paleotemperature proxies in eastern North America. However, individual pollen records show large differences in timing, rates, and amplitudes of inferred temperature change, indicating caution with paleoclimatic inferences based on single-site pollen records. From 16.0 to 10.0ka, both proxies indicate that regional temperatures rose by ∼10 °C, roughly double the ∼5 °C estimates for the Northern Hemisphere reported in prior syntheses. Change-point analysis of the pollen stack shows accelerated warming at 14.0 ± 1.2ka, cooling at 12.6 ± 0.4ka, and warming from 11.6 ± 0.5ka into the Holocene. The timing of Bølling-Allerød (B-A) warming and YD onset in our records lag by ∼300–500 years those reported in syntheses of temperature records from the northern mid-latitudes. This discrepancy is too large to be attributed to uncertainties in

Integration of climatic indices in an objective probabilistic model for establishing and mapping viticultural climatic zones in a region

Science.gov (United States)

Moral, Francisco J.; Rebollo, Francisco J.; Paniagua, Luis L.; García, Abelardo; Honorio, Fulgencio

2016-05-01

Different climatic indices have been proposed to determine the wine suitability in a region. Some of them are related to the air temperature, but the hydric component of climate should also be considered which, in turn, is influenced by the precipitation during the different stages of the grapevine growing and ripening periods. In this study, we propose using the information obtained from ten climatic indices [heliothermal index (HI), cool night index (CI), dryness index (DI), growing season temperature (GST), the Winkler index (WI), September mean thermal amplitude (MTA), annual precipitation (AP), precipitation during flowering (PDF), precipitation before flowering (PBF), and summer precipitation (SP)] as inputs in an objective and probabilistic model, the Rasch model, with the aim of integrating the individual effects of them, obtaining the climate data that summarize all main climatic indices, which could influence on wine suitability from a climate viewpoint, and utilizing the Rasch measures to generate homogeneous climatic zones. The use of the Rasch model to estimate viticultural climatic suitability constitutes a new application of great practical importance, enabling to rationally determine locations in a region where high viticultural potential exists and establishing a ranking of the climatic indices which exerts an important influence on wine suitability in a region. Furthermore, from the measures of viticultural climatic suitability at some locations, estimates can be computed using a geostatistical algorithm, and these estimates can be utilized to map viticultural climatic zones in a region. To illustrate the process, an application to Extremadura, southwestern Spain, is shown.

Modern Climate Analogues of Late-Quaternary Paleoclimates for the Western United States.

Science.gov (United States)

Mock, Cary Jeffrey

This study examined spatial variations of modern and late-Quaternary climates for the western United States. Synoptic climatological analyses of the modern record identified the predominate climatic controls that normally produce the principal modes of spatial climatic variability. They also provided a modern standard to assess past climates. Maps of the month-to-month changes in 500 mb heights, sea-level pressure, temperature, and precipitation illustrated how different climatic controls govern the annual cycle of climatic response. The patterns of precipitation ratios, precipitation bar graphs, and the seasonal precipitation maximum provided additional insight into how different climatic controls influence spatial climatic variations. Synoptic-scale patterns from general circulation model (GCM) simulations or from analyses of climatic indices were used as the basis for finding modern climate analogues for 18 ka and 9 ka. Composite anomaly maps of atmospheric circulation, precipitation, and temperature were compared with effective moisture maps compiled from proxy data to infer how the patterns, which were evident from the proxy data, were generated. The analyses of the modern synoptic climatology indicate that smaller-scale climatic controls must be considered along with larger-scale ones in order to explain patterns of spatial climate heterogeneity. Climatic extremes indicate that changes in the spatial patterns of precipitation seasonality are the exception rather than the rule, reflecting the strong influence of smaller-scale controls. Modern climate analogues for both 18 ka and 9 ka clearly depict the dry Northwest/wet Southwest contrast that is suggested by GCM simulations and paleoclimatic evidence. 18 ka analogues also show the importance of smaller-scale climatic controls in explaining spatial climatic variation in the Northwest and northern Great Plains. 9 ka analogues provide climatological explanations for patterns of spatial heterogeneity over several

Calibration and application of the branched GDGT temperature proxy on East African lake sediments

NARCIS (Netherlands)

Loomis, S.E.; Russell, J.M.; Ladd, B.; Street-Perrott, F.A.; Sinninghe Damsté, J.S.

2012-01-01

Branched glycerol dialkyl glycerol tetraethers (brGDGTs) are a novel proxy for mean annual air temperature (MAAT) and have the potential to be broadly applicable to climate reconstruction using lacustrine sediments. Several calibrations have been put forth relating brGDGT distributions to MAAT using

Reconstruction of late Quaternary marine and terrestrial environmental conditions of Northwest Africa and Southeast Australia : a multiple organic proxy study using marine sediments

NARCIS (Netherlands)

Alfama Lopes dos Santos, R.

2012-01-01

NW Africa and SE Australia are regions which are particularly vulnerable to climate change. In this thesis, organic proxies are used from marine sediment cores to reconstruct past environmental conditions from these areas. In sediments from NW Africa, the UK'37 showed an efficient proxy for sea

Improved end-member characterization of modern organic matter pools in the Ohrid Basin (Albania, Macedonia) and evaluation of new palaeoenvironmental proxies

Science.gov (United States)

Holtvoeth, J.; Rushworth, D.; Imeri, A.; Cara, M.; Vogel, H.; Wagner, T.; Wolff, G. A.

2015-08-01

We present elemental, lipid biomarker and compound-specific isotope (δ13C, δ2H) data for soils and leaf litter collected in the catchment of Lake Ohrid (Albania, Macedonia), as well as macrophytes, particulate organic matter and sediments from the lake itself. Lake Ohrid provides an outstanding archive of continental environmental change of at least 1.2 M years and the purpose of our study is to ground truth organic geochemical proxies that we developed in order to study past changes in the terrestrial biome. We show that soils dominate the lipid signal of the lake sediments rather than the vegetation or aquatic biomass, while compound-specific isotopes (δ13C, δ2H) determined for n-alkanoic acids confirm a dominant terrestrial source of organic matter to the lake. There is a strong imprint of suberin monomers on the composition of total lipid extracts and chain-length distributions of n-alkanoic acids, n-alcohols, ω-hydroxy acids and α,ω-dicarboxylic acids. Our end-member survey identifies that ratios of mid-chain length suberin-derived to long-chain length cuticular-derived alkyl compounds as well as their average chain length distributions can be used as new molecular proxies of organic matter sources to the lake. We tested these for the 8.2 ka event, a pronounced and widespread Holocene climate fluctuation. In SE Europe climate became drier and cooler in response to the event, as is clearly recognizable in the carbonate and organic carbon records of Lake Ohrid sediments. Our new proxies indicate biome modification in response to hydrological changes, identifying two phases of increased soil OM supply, first from topsoils and then from mineral soils. Our study demonstrates that geochemical fingerprinting of terrestrial OM should focus on the main lipid sources, rather than the living biomass. Both can exhibit climate-controlled variability, but are generally not identical.

Improved end-member characterisation of modern organic matter pools in the Ohrid Basin (Albania, Macedonia) and evaluation of new palaeoenvironmental proxies

Science.gov (United States)

Holtvoeth, J.; Rushworth, D.; Copsey, H.; Imeri, A.; Cara, M.; Vogel, H.; Wagner, T.; Wolff, G. A.

2016-02-01

We present elemental, lipid biomarker and, in the supplement, compound-specific isotope (δ13C, δ2H) data for soils and leaf litter collected in the catchment of Lake Ohrid (Albania, Macedonia), as well as macrophytes, particulate organic matter and sediments from the lake itself. Lake Ohrid provides an outstanding archive of continental environmental change of at least 1.2 million years and the purpose of our study is to ground truth organic geochemical proxies that we developed in order to study past changes in the terrestrial biome. We show that soils dominate the lipid signal of the lake sediments rather than the vegetation or aquatic biomass. There is a strong imprint of suberin monomers on the composition of total lipid extracts and chain-length distributions of n-alkanoic acids, n-alcohols, ω-hydroxy acids and α, ω-dicarboxylic acids. Our end-member survey identifies that ratios of mid-chain length suberin-derived to long-chain length cuticular-derived alkyl compounds as well as their average chain length distributions can be used as new molecular proxies of organic matter sources to the lake. We tested these for the 8.2 ka event, a pronounced and widespread Holocene climate fluctuation. In SE Europe climate became drier and cooler in response to the event, as is clearly recognisable in the carbonate and organic carbon records of Lake Ohrid sediments. Our new proxies indicate biome modification in response to hydrological changes, identifying two phases of increased soil organic matter (OM) supply, first from soils with moderately degraded OM and then from more degraded soils. Our study demonstrates that geochemical fingerprinting of terrestrial OM should focus on the main lipid sources, rather than the living biomass. Both can exhibit climate-controlled variability, but are generally not identical.

Climatic indicators over Catalonia during the last century

Science.gov (United States)

Busto, M.; Prohom, M.

2010-09-01

The Meteorological Service of Catalonia releases a yearly bulletin whose main objective is to try to detect climate trends over Catalonia during the last decades. Climate indicators are obtained from the analysis of historical daily air temperature, sea temperature and rainfall series. Those series have been first completed, analyzed for quality control and homogenized to ensure its final reliability. Regarding homogenization, monthly air temperature series have been tested and corrected according to the methodology proposed by Caussinus and Mestre (2004). For the two longest air temperature series, the calculated correction factors have been transferred to the daily values following Vincent et al. (2002) recommendations, while no significant inhomogeneities have been detected for precipitation series. The analysis of temperature trends, for the period 1950-2010, of 17 selected climatic series spread across the territory shows a common temperature increase between +0.19 to +0.24 °C/decade. This warming trend is uniform and no specific sub-regional trends are detected. Furthermore, the seasonal approach reveals that mean maximum temperature increases at a higher rate than mean minimum temperature. The summer temperature rise is the most significant, between +0.32 and +0.44 °C/decade, while autumn is the only season showing no significant positive trend. The summer maximum temperature shows the highest increase, exceeding +0.39 °C/decade in all the 17 series. The climatic extremes analysis of the longest Catalan series (Ebre Observatory in Roquetes, Tarragona, since 1905 and Fabra Observatory in Barcelona since 1913) reveals an increase in the number of summer days, tropical nights, minimum of maximum temperature, warm days and warm nights, and a decrease in the number of frost days, cold nights, cold days and cold spell duration indicator. Concerning precipitation, the only significant trend is the reduction of snow days. These trends were calculated according to

Planktonic Foraminifera Proxies Calibration Off the NW Iberian Margin: Nutrients Approach

Science.gov (United States)

Salgueiro, E.; Castro, C. G.; Zuniga, D.; Martin, P. A.; Groeneveld, J.; de la Granda, F.; Villaceiros-Robineau, N.; Alonso-Perez, F.; Alberto, A.; Rodrigues, T.; Rufino, M. M.; Abrantes, F. F. G.; Voelker, A. H. L.

2014-12-01

Planktonic foraminifera (PF) shells preserved in marine sediments are a useful tool to reconstruct productivity conditions at different geological timescales. However, the accuracy of these paleoreconstructions depends on the data set and calibration quality. Several calibration works have been defining and improving the use of proxies for productivity and nutrient cycling parameters. Our contribution is centred on a multi-proxy calibration at a regional coastal upwelling system. To minimize the existing uncertainties affecting the use of trace elements and C stable isotopes as productivity proxy in the high productivity upwelling areas, we investigate the content and distribution of Ba/Ca and δ13C in the water column, its transference into the planktonic foraminifera shells, and, how the living planktonic foraminifera Ba/Ca and δ13C signal is related to the same planktonic foraminiferal species preserved in the sediment record. This study is based on a large data set from two stations (RAIA - 75m water depth, and CALIBERIA - 350m water depth) located off the NW Iberian margin (41.5-42.5ºN; 9-10ºW), and includes: i) two year monthly water column data (temperature, salinity, nutrients, chlorophyll a, Ba/Ca, and δ13C-DIC); ii) seasonal Ba/Ca, δ13C in several living PF species at both stations; and iii) Ba/Ca and δ13C in several PF species from a large set of core-top sediment samples in the study region. Additionally, total organic carbon and total alkenones were also measured in the sediment. Our results showed the link between productivity proxies in the surface sediment foraminifera assemblage and the processes regulating the actual phytoplankton dynamics in an upwelling area. The understanding of this relationship has special relevance since it gives fundamental information related to the past oceanic biogeochemistry and/or climate and improves the prevision of future changes against possible climate variability due to anthropogenic forcing.

A 350 Year Cloud Cover Reconstruction Deduced from Caribbean Coral Proxies

Science.gov (United States)

Winter, Amos; Sammarco, Paul; Mikolajewicz, Uwe; Jury, Mark; Zanchettin, Davide

2015-04-01

Clouds are a major factor contributing to climate change with respect to a variety of effects on the earth's climates, primarily radiative effects, amelioration of heating, and regional changes in precipitation patterns. There have been very few studies of decadal and longer term changes in cloud cover in the tropics and sub-tropics, both over land and the ocean. In the tropics, there is great uncertainty regarding how global warming will affect cloud cover. Observational satellite data is so short that it is difficult to discern any temporal trends. The skeletons of scleractinian corals are considered to contain among the best records of high-resolution (sub-annual) environmental variability in the tropical and sub-tropical oceans. Corals generally live in well-mixed coastal regions and can often record environmental conditions of large areas of the upper ocean. This is particularly the case at low latitudes. Scleractinian corals are sessile, epibenthic fauna, and the type of environmental information recorded at the location where the coral has been living is dependent upon the species of coral considered and proxy index of interest. Zooxanthellate hermatypic corals in tropical and sub-tropical seas precipitate CaCO3 skeletons as they grow. This growth is made possible through the manufacture of CaCO3 crystals, facilitated by the zooxanthellae. During the process of crystallization, the holobiont binds carbon of different isotopes into the crystals. Stable carbon isotope concentrations vary with a variety of environmental conditions. In the Caribbean, δ13C in corals of the species Montastraea faveolata can be used as a proxy for changes in cloud cover. In this contribution, we will demonstrate that the stable isotope 13C varies concomitantly with cloud cover and present a new reconstruction of cloud cover over the Caribbean Sea that extends back to the year 1760. We will show that there is good agreement between the main features of our coral proxy record of

Development of key indicators to quantify the health impacts of climate change on Canadians.

Science.gov (United States)

Cheng, June J; Berry, Peter

2013-10-01

This study aimed at developing a list of key human health indicators for quantifying the health impacts of climate change in Canada. A literature review was conducted in OVID Medline to identify health morbidity and mortality indicators currently used to quantify climate change impacts. Public health frameworks and other studies of climate change indicators were reviewed to identify criteria with which to evaluate the list of proposed key indicators and a rating scale was developed. Total scores for each indicator were calculated based on the rating scale. A total of 77 health indicators were identified from the literature. After evaluation using the chosen criteria, 8 indicators were identified as the best for use. They include excess daily all-cause mortality due to heat, premature deaths due to air pollution (ozone and particulate matter 2.5), preventable deaths from climate change, disability-adjusted life years lost from climate change, daily all-cause mortality, daily non-accidental mortality, West Nile Disease incidence, and Lyme borreliosis incidence. There is need for further data and research related to health effect quantification in the area of climate change.

Open access to Water Indicators for Climate Change Adaptation: proof-of-concept for the Copernicus Climate Change Service (C3S)

Science.gov (United States)

Lottle, Lorna; Arheimer, Berit; Gyllensvärd, Frida; Dejong, Fokke; Ludwig, Fulco; Hutjes, Ronald; Martinez, Bernat

2017-04-01

Copernicus Climate Change Service (C3S) is still in the development phase and will combine observations of the climate system with the latest science to develop authoritative, quality-assured information about the past, current and future states of the climate and climate dependent sectors in Europe and worldwide. C3S will provide key indicators on climate change drivers and selected sectorial impacts. The aim of these indicators will be to support adaptation and mitigation. This presentation will show one service already operational as a proof-of-concept of this future climate service. The project "Service for Water Indicators in Climate Change Adaptation" (SWICCA) has developed a sectorial information service for water management. It offers readily available climate-impact data, for open access from the web-site http://swicca.climate.copernicus.eu/. The development is user-driven with the overall goal to speed up the workflow in climate-change adaptation of water management across Europe. The service is co-designed by consultant engineers and agencies in 15 case-studies spread out over the continent. SWICCA has an interactive user-interface, which shows maps and graphs, and facilitates data download in user-friendly formats. In total, more than 900 open dataset are given for various hydrometeorological (and a few socioeconomical) variables, model ensembles, resolutions, time-periods and RCPs. The service offers more than 40 precomputed climate impact indicators (CIIs) and transient time-series of 4 essential climate variables ECVs) with high spatial and temporal resolution. To facilitate both near future and far future assessments, SWICCA provides the indicators for different time ranges; normally, absolute values are given for a reference period (e.g. 1971-2000) and the expected future changes for different 30-year periods, such as early century (2011-2040), mid-century (2041-2070) and end-century (2071-2100). An ensemble of model results is always given to

Multi-scale analysis of teleconnection indices: climate noise and nonlinear trend analysis

Directory of Open Access Journals (Sweden)

C. Franzke

2009-02-01

Full Text Available The multi-scale nature and climate noise properties of teleconnection indices are examined by using the Empirical Mode Decomposition (EMD procedure. The EMD procedure allows for the analysis of non-stationary time series to extract physically meaningful intrinsic mode functions (IMF and nonlinear trends. The climatologically relevant monthly mean teleconnection indices of the North Atlantic Oscillation (NAO, the North Pacific index (NP and the Southern Annular Mode (SAM are analyzed.

The significance of IMFs and trends are tested against the null hypothesis of climate noise. The analysis of surrogate monthly mean time series from a red noise process shows that the EMD procedure is effectively a dyadic filter bank and the IMFs (except the first IMF are nearly Gaussian distributed. The distribution of the variance contained in IMFs of an ensemble of AR(1 simulations is nearly χ² distributed. To test the statistical significance of the IMFs of the teleconnection indices and their nonlinear trends we utilize an ensemble of corresponding monthly averaged AR(1 processes, which we refer to as climate noise. Our results indicate that most of the interannual and decadal variability of the analysed teleconnection indices cannot be distinguished from climate noise. The NP and SAM indices have significant nonlinear trends, while the NAO has no significant trend when tested against a climate noise hypothesis.

Limiting exercise options: depending on a proxy may inhibit exercise self-management.

Science.gov (United States)

Shields, Christopher A; Brawley, Lawrence R

2007-07-01

We examined the influence of proxy-assistance on exercisers' social cognitions and behavior. Fifty-six fitness class participants reported preference for proxy-assistance and reacted to exercising in different contexts. A 2 (proxy-led vs self-managed exercise context) by 2 (preferred assistance) MANOVA revealed significant assistance by context interactions for self-regulatory efficacy (SRE) and difficulty. Regarding self-managed exercise, high-assistance individuals expressed lower SRE and higher difficulty. Chi-square analysis revealed that significantly fewer high-assistance participants chose self-managed exercise. A one-way MANOVA on preferred assistance indicated that high-assistance participants were less confident, satisfied and perceived their self-managed exercise as more difficult. Results support Bandura's theorizing that use of a proxy can limit SRE of those preferring the proxy's control of their behavior.

Investigating the consistency between proxy-based reconstructions and climate models using data assimilation: a mid-Holocene case study

NARCIS (Netherlands)

A. Mairesse; H. Goosse; P. Mathiot; H. Wanner; S. Dubinkina (Svetlana)

2013-01-01

htmlabstractThe mid-Holocene (6 kyr BP; thousand years before present) is a key period to study the consistency between model results and proxy-based reconstruction data as it corresponds to a standard test for models and a reasonable number of proxy-based records is available. Taking advantage of

Testing a statistical method of global mean palotemperature estimations in a long climate simulation

Energy Technology Data Exchange (ETDEWEB)

Zorita, E.; Gonzalez-Rouco, F. [GKSS-Forschungszentrum Geesthacht GmbH (Germany). Inst. fuer Hydrophysik

2001-07-01

Current statistical methods of reconstructing the climate of the last centuries are based on statistical models linking climate observations (temperature, sea-level-pressure) and proxy-climate data (tree-ring chronologies, ice-cores isotope concentrations, varved sediments, etc.). These models are calibrated in the instrumental period, and the longer time series of proxy data are then used to estimate the past evolution of the climate variables. Using such methods the global mean temperature of the last 600 years has been recently estimated. In this work this method of reconstruction is tested using data from a very long simulation with a climate model. This testing allows to estimate the errors of the estimations as a function of the number of proxy data and the time scale at which the estimations are probably reliable. (orig.)

Future tendencies of climate indicators important for adaptation and mitigation strategies in forestry

Science.gov (United States)

Galos, Borbala; Hänsler, Andreas; Gulyas, Krisztina; Bidlo, Andras; Czimber, Kornel

2014-05-01

Climate change is expected to have severe impacts in the forestry sector, especially in low-elevation regions in Southeast Europe, where forests are vulnerable and sensitive to the increasing probability and severity of climatic extremes, especially to droughts. For providing information about the most important regional and local risks and mitigation options for the Carpathian basin, a GIS-supported Decision Support System is under development. This study focuses on the future tendencies of climate indicators that determine the distribution, growth, health status and production of forests as well as the potential pests and diseases. For the analyses the climate database of the Decision Support System has been applied, which contains daily time series for precipitation and temperature means and extremes as well as derived climate indices for 1961-2100. For the future time period, simulation results of 12 regional climate models are included (www.ensembles-eu.org) based on the A1B emission scenario. The main results can be summarized as follows: · The projected change of the climate indices (e.g. total number of hot days, frost days, dry days, consecutive dry periods) and forestry indices (e.g. Ellenberg climate quotient, Forestry aridity index; Tolerance index for beech) indicates the warming and drying of the growing season towards the end of the 21st century. These can have severe consequences on the ecosystem services of forests. · The climatic suitable area of the native tree species is projected to move northwards and upwards in the mountains, respectively. For beech (Fagus sylvatica L.) this shift would mean the drastic shrink of the distribution area in the analyzed region. · The characteristic climate conditions that are expected in the Carpathian basin in the second half of the century, are now located southeastern from the case study region. In this way, the potential future provenance regions can be determined. Results provide input for the climate

The Last Interglacial-Glacial cycle (MIS 5-2) re-examined based on long proxy records from central and northern Europe

Science.gov (United States)

Helmens, Karin F.

2014-02-01

Current multi-proxy studies on a long sediment sequence preserved at Sokli (N Finland), i.e. in the central area of Fennoscandian glaciations, are drastically changing classic ideas of glaciations, vegetation and climate in northern Europe during the Late Pleistocene. The sediments in the Sokli basin have escaped major glacial erosion due to non-typical bedrock conditions. In this review, the Sokli record is compared in great detail with other long proxy records from central, temperate and northern, boreal Europe. These comprise the classic records of La Grande Pile (E France) and Oerel (N Germany) and more recently obtained records from Horoszki Duże (E Poland) and Lake Yamozero (NW Russia). The focus of the review is on pollen, lithology and macrofossil- and insect-based temperature inferences. The long records are further compared with recent proxy data from nearby terrestrial sites as well as with the rapidly accumulating high-resolution proxy data from the ocean realm. The comparison allows a re-examination of the environmental history and climate evolution of the Last Interglacial-Glacial (LI-G) cycle (MIS 5-2). It shows that environmental and climate conditions during MIS 5 (ca 130-70 ka BP) were distinctly different from those during MIS 4-2 (ca 70-15 ka BP). MIS 5 is characterized by three long forested intervals (broadly corresponding to MIS 5e, 5c, 5a), both in temperate and northern boreal Europe. These mild periods were interrupted by two short, relatively cold and dry intervals (MIS 5d and 5b) with mountain-centered glaciation in Fennoscandia. Millennial scale climate events were superimposed upon these longer lasting climate fluctuations. The time interval encompassing MIS 4-2 shows open vegetation. It is characterized by two glacial maxima (MIS 4 and 2) with sub-continental scale glaciation over northern Europe and dry conditions in strongly continental eastern European settings. High amplitude climate oscillations of millennial duration

Speleothem carbon isotopes in the tropics: a proxy for vegetation and what they reveal about the demise of Homo floresiensis

Science.gov (United States)

Scroxton, N.; Gagan, M. K.; Ayliffe, L. K.; Hellstrom, J.; Cheng, H.; Edwards, R.; Zhao, J.; Hantoro, W. S.; Rifai, H.; Scott-Gagan, H.; Cowley, J. A.; Suwargadi, B. W.

2013-12-01

Most long-term speleothem climate records focus on δ18O (Cruz Jr. et al. 2005, Wang et al. 2005, Meckler et al. 2012, Carolin et al. 2013). In tropical regions, where temperature variability is relatively small, speleothem δ18O serves as a proxy for precipitation amount. On orbital timescales, changes in moisture source, sea level and global ice volume also influence speleothem δ18O. As both δ18O and δ13C are measured simultaneously, a wealth of potential paleoclimatic information from the δ13C records for numerous sites awaits publication. However, δ13C is less well understood as an environmental proxy, and a simple control and explanation may not be forthcoming. We present a new 92,000-year long speleothem δ13C record for Liang Luar cave in Flores, Indonesia. Here, δ13C acts as a proxy for soil CO2 production above the cave, which is strongly linked to vegetative changes. Since vegetation and soil CO2 production are closely linked to a climatic control, changes in speleothem δ13C can be considered an environmental response to climate change. The Liang Luar δ13C record mainly tracks the δ18O, indicating close affiliation between vegetation and climate. Peak vegetation cover and soil activity (lower δ13C) occur in the early Holocene. The Last Glacial Maximum does not have notably higher δ13C than Isotope Stages 3 and 5a. δ13C variability in the glacial is much higher than that in the Holocene. Differences between the δ13C and δ18O records indicate periods of vegetative change without a climatic cause. The largest increase in δ13C (8‰) during the last 90kyr occurred at 68kyr BP. This anomalous δ13C excursion represents a major loss of vegetation around Liang Luar. The last surviving non-human member of the Homo genus: Homo floresiensis, disappeared from the stratigraphic record in nearby Liang Bua cave between 17 and 10kyr BP (Roberts et al. 2009). The cause of the disappearance, (e.g. climate change, volcanic catastrophe or human competition

Ecoclimatic indicators to study crop suitability in present and future climatic conditionsTIC CONDITIONS

Science.gov (United States)

Caubel, Julie; Garcia de Cortazar Atauri, Inaki; Huard, Frédéric; Launay, Marie; Ripoche, Dominique; Gouache, David; Bancal, Marie-Odile; Graux, Anne-Isabelle; De Noblet, Nathalie

2013-04-01

Climate change is expected to affect both regional and global food production through changes in overall agroclimatic conditions. It is therefore necessary to develop simple tools of crop suitability diagnosis in a given area so that stakeholders can envisage land use adaptations under climate change conditions. The most common way to investigate potential impacts of climate on the evolution of agrosystems is to make use of an array of agroclimatic indicators, which provide synthetic information derived from climatic variables and calculated within fixed periods (i.e. January first - 31th July). However, the information obtained during these periods does not enable to take account of the plant response to climate. In this work, we present some results of the research program ORACLE (Opportunities and Risks of Agrosystems & forests in response to CLimate, socio-economic and policy changEs in France (and Europe). We proposed a suite of relevant ecoclimatic indicators, based on temperature and rainfall, in order to evaluate crop suitability for both present and new climatic conditions. Ecoclimatic indicators are agroclimatic indicators (e.g., grain heat stress) calculated during specific phenological phases so as to take account of the plant response to climate (e.g., the grain filling period, flowering- harvest). These indicators are linked with the ecophysiological processes they characterize (for e.g., the grain filling). To represent this methodology, we studied the suitability of winter wheat in future climatic conditions through three distinct French sites, Toulouse, Dijon and Versailles. Indicators have been calculated using climatic data from 1950 to 2100 simulated by the global climate model ARPEGE forced by a greenhouse effect corresponding to the SRES A1B scenario. The Quantile-Quantile downscaling method was applied to obtain data for the three locations. Phenological stages (emergence, ear 1 cm, flowering, beginning of grain filling and harvest) have been

Reconstruction of fire regimes through integrated paleoecological proxy data and ecological modeling.

Science.gov (United States)

Iglesias, Virginia; Yospin, Gabriel I; Whitlock, Cathy

2014-01-01

Fire is a key ecological process affecting vegetation dynamics and land cover. The characteristic frequency, size, and intensity of fire are driven by interactions between top-down climate-driven and bottom-up fuel-related processes. Disentangling climatic from non-climatic drivers of past fire regimes is a grand challenge in Earth systems science, and a topic where both paleoecology and ecological modeling have made substantial contributions. In this manuscript, we (1) review the use of sedimentary charcoal as a fire proxy and the methods used in charcoal-based fire history reconstructions; (2) identify existing techniques for paleoecological modeling; and (3) evaluate opportunities for coupling of paleoecological and ecological modeling approaches to better understand the causes and consequences of past, present, and future fire activity.

Impact of prehistoric cooking practices on paleoenvironmental proxies in shell midden constituents

Science.gov (United States)

Müller, Peter; Staudigel, Philip; Murray, Sean T.; Westphal, Hildegard; Swart, Peter K.

2016-04-01

Paleoenvironmental proxy records such as oxygen isotopes of calcareous skeletal structures like fish otoliths or mollusk shells provide highest-resolution information about environmental conditions experienced by the organism. Accumulations of such skeletal structures by ancient coastal populations in so called "shell midden" deposits provide us with sub-seasonally resolved paleoclimate records covering time spans up to several millennia. Given their high temporal resolution, these deposits are increasingly used for paleoclimate reconstructions and complement our understanding of ancient climate changes. However, gathered as comestibles, most of these skeletal remains were subject to prehistoric cooking methods prior to deposition. The associated alteration of the chemical proxy signatures as well as the subsequent error for paleoenvironmental reconstructions remained almost entirely neglected so far. Here, we present clumped isotope, conventional oxygen and carbon isotopes as well as element:Ca ratios measured in modern bivalve shells after exposing them to different prehistoric cooking methods. Our data show that most cooking methods considerably alter commonly used paleoclimate proxy systems which can lead to substantial misinterpretations of ancient climate conditions. Since the magnitude of chemical alteration is not distinguishable from natural temperature variability in most coastal settings, the alteration of shell midden constituents by prehistoric cooking remains likely unnoticed in most cases. Thus, depending on the cooking method, pre-depositional heating might have introduced considerable errors into previous paleoclimate studies. However, our data also show that clumped isotope thermometry represents a suitable diagnostic tool to detect such pre-depositional cooking events and also allows differentiating between the most commonly applied prehistoric cooking methods.

Vulnerability of Agriculture to Climate Change as Revealed by Relationships between Simulated Crop Yield and Climate Change Indices

Science.gov (United States)

King, A. W.; Absar, S. M.; Nair, S.; Preston, B. L.

2012-12-01

The vulnerability of agriculture is among the leading concerns surrounding climate change. Agricultural production is influenced by drought and other extremes in weather and climate. In regions of subsistence farming, worst case reductions in yield lead to malnutrition and famine. Reduced surplus contributes to poverty in agrarian economies. In more economically diverse and industrialized regions, variations in agricultural yield can influence the regional economy through market mechanisms. The latter grows in importance as agriculture increasingly services the energy market in addition to markets for food and fiber. Agriculture is historically a highly adaptive enterprise and will respond to future changes in climate with a variety of adaptive mechanisms. Nonetheless, the risk, if not expectation, of increases in climate extremes and hazards exceeding historical experience motivates scientifically based anticipatory assessment of the vulnerability of agriculture to climate change. We investigate the sensitivity component of that vulnerability using EPIC, a well established field-scale model of cropping systems that includes the simulation of economic yield. The core of our analysis is the relationship between simulated yield and various indices of climate change, including the CCI/CLIVAR/JCOM ETCCDI indices, calculated from weather inputs to the model. We complement this core with analysis using the DSSAT cropping system model and exploration of relationships between historical yield statistics and climate indices calculated from weather records. Our analyses are for sites in the Southeast/Gulf Coast region of the United States. We do find "tight" monotonic relationships between annual yield and climate for some indices, especially those associated with available water. More commonly, however, we find an increase in the variability of yield as the index value becomes more extreme. Our findings contribute to understanding the sensitivity of crop yield as part of

Heinrich event 4 characterized by terrestrial proxies in southwestern Europe

Directory of Open Access Journals (Sweden)

J. M. López-García

2013-05-01

Full Text Available Heinrich event 4 (H4 is well documented in the North Atlantic Ocean as a cooling event that occurred between 39 and 40 Ka. Deep-sea cores around the Iberian Peninsula coastline have been analysed to characterize the H4 event, but there are no data on the terrestrial response to this event. Here we present for the first time an analysis of terrestrial proxies for characterizing the H4 event, using the small-vertebrate assemblage (comprising small mammals, squamates and amphibians from Terrassa Riera dels Canyars, an archaeo-palaeontological deposit located on the seaboard of the northeastern Iberian Peninsula. This assemblage shows that the H4 event is characterized in northeastern Iberia by harsher and drier terrestrial conditions than today. Our results were compared with other proxies such as pollen, charcoal, phytolith, avifauna and large-mammal data available for this site, as well as with the general H4 event fluctuations and with other sites where H4 and the previous and subsequent Heinrich events (H5 and H3 have been detected in the Mediterranean and Atlantic regions of the Iberian Peninsula. We conclude that the terrestrial proxies follow the same patterns as the climatic and environmental conditions detected by the deep-sea cores at the Iberian margins.

Proxy indicators for identifying iron deficiency among anemic vegetarians in an area prevalent for thalassemia and hemoglobinopathies.

Science.gov (United States)

Wongprachum, Kasama; Sanchaisuriya, Kanokwan; Sanchaisuriya, Pattara; Siridamrongvattana, Sirivara; Manpeun, Suwanna; Schlep, Frank P

2012-01-01

The study aimed to determine the proportion of iron deficiency (ID) anemia (IDA) among vegans in northeast Thailand and to explore whether mathematical formulas derived from red blood cell (RBC) indices are applicable for IDA screening in the study population. Blood samples from 234 individuals (age 6-45 years) living in a vegan community were taken. Complete blood cell count, serum ferritin, hemoglobin profiles and DNA analysis for α-thalassemia were determined. Anemia was defined using the WHO criteria adjusted for age and sex. Serum ferritin thalassemia and hemoglobinopathies was 56.4% (95% CI = 49.8-62.9%). Of the anemic participants, 45.4% had ID. Based on the receiver-operating characteristic curve analysis, 4 formulas were applicable for predicting ID among anemic individuals (highest sensitivity of 86.4%). The proposed formulas might be used as proxy indicators for the identification of ID among anemic children and adult vegans if more sophisticated laboratory determinations are not available due to limited financial resources. Copyright © 2012 S. Karger AG, Basel.

Climate indices of Iran under climate change

Directory of Open Access Journals (Sweden)

alireza kochaki

2009-06-01

Full Text Available Global warming will affect all climatic variables and particularly rainfall patterns. The purpose of present investigation was to predict climatic parameters of Iran under future climate change and to compare them with the present conditions. For this reason, UKMO General Circulation Model was used for the year 2025 and 2050. By running the model, minimum and maximum monthly temperature and also maximum monthly rainfall for the representative climate stations were calculated and finally the effects of climate change on these variables based on pre-determined scenarios was evaluated. The results showed that averaged over all stations, mean temperature increase for spring in the year 2025 and 2050 will be 3.1 and 3.9, for summer 3.8 and 4.7, for autumn 2.3 and 3 and for winter 2.0 and 2.4 ºC, respectively. This increase will be more pronounced from North to the South and from East to the West parts of the country. Mean decrease in autumn rainfall for the target years of 2025 and 2050 will be 8 and 11 percent, respectively. This decrease is negligible for summer months. Length of dry season for the years 2025 and 2050 will be increased, respectively up to 214 and 223 days due to combined effects of increased temperature and decreased rainfall.

Quantitative Holocene climatic reconstructions for the lower Yangtze region of China

Science.gov (United States)

Li, Jianyong; Dodson, John; Yan, Hong; Wang, Weiming; Innes, James B.; Zong, Yongqiang; Zhang, Xiaojian; Xu, Qinghai; Ni, Jian; Lu, Fengyan

2018-02-01

Quantitative proxy-based and high-resolution palaeoclimatic datasets are scarce for the lower reaches of the Yangtze River (LYR) basin. This region is in a transitional vegetation zone which is climatologically sensitive; and as a birthplace for prehistorical civilization in China, it is important to understand how palaeoclimatic dynamics played a role in affecting cultural development in the region. We present a pollen-based and regionally-averaged Holocene climatic twin-dataset for mean total annual precipitation (PANN) and mean annual temperature (TANN) covering the last 10,000 years for the LYR region. This is based on the technique of weighted averaging-partial least squares regression to establish robust calibration models for obtaining reliable climatic inferences. The pollen-based reconstructions generally show an early Holocene climatic optimum with both abundant monsoonal rainfall and warm thermal conditions, and a declining pattern of both PANN and TANN values in the middle to late Holocene. The main driving forces behind the Holocene climatic changes in the LYR area are likely summer solar insolation associated with tropical or subtropical macro-scale climatic circulations such as the Intertropical Convergence Zone (ITCZ), Western Pacific Subtropical High (WPSH), and El Niño/Southern Oscillation (ENSO). Regional multi-proxy comparisons indicate that the Holocene variations in precipitation and temperature for the LYR region display an in-phase relationship with other related proxy records from southern monsoonal China and the Indian monsoon-influenced regions, but are inconsistent with the Holocene moisture or temperature records from northern monsoonal China and the westerly-dominated region in northwestern China. Overall, our comprehensive palaeoclimatic dataset and models may be significant tools for understanding the Holocene Asian monsoonal evolution and for anticipating its future dynamics in eastern Asia.

Ecoclimatic indicators to study climate suitability of areas for the cultivation of specific crops

Science.gov (United States)

Caubel, J.; Garcia de Cortazar Atauri, I.; Cufi, J.; Huard, F.; Launay, M.; Ripoche, D.; Graux, A.; deNoblet, N.

2013-12-01

Climatic conditions play a fundamental role in the suitability of geographical areas for cropping. In the context of climate change, we could expect changes in overall climatic conditions and so, on the suitability for cropping. Therefore, assessing the future climate suitability of areas for cropping is decisive for anticipating agriculture in a given area. Moreover, it is crucial to have access to the split up information concerning the effect of climate on the achievement of the main ecophysiological processes and cultural practices taking place during the crop cycle. In this way, stakeholders can envisage land use adaptations under climate change conditions, such as changes in cultural practices or development of new varieties for example. We proposed an aggregation tool of ecoclimatic indicators to design evaluation trees of climate suitability of areas for cropping, GETARI (Generic Evaluation Tool of Ecoclimatic Indicators). It calculates an overall climate suitability index at the annual scale, from a designed evaluation tree. This aggregation tool allows to characterize climate suitability according to crop ecophysiology, grain/fruit quality or crop management. GETARI proposes the major ecophysiological processes and cultural practices taking place during phenological periods, together with the climatic effects that are known to affect their achievement. The climatic effects on the ecophysiological processes (or cultural practices) during phenological periods are captured by the ecoclimatic indicators, which are agroclimatic indicators calculated over phenological periods. They give information about crop response to climate through ecophysiological or agronomic thresholds. Those indices of suitability are normalized and aggregated according to aggregation rules in order to compute an overall climate index. In order to illustrate how GETARI can be used, we designed evaluation trees in order to study the climate suitability for maize cropping regarding

Development of key indicators to quantify the health impacts of climate change on Canadians

OpenAIRE

Cheng, June J.; Berry, Peter

2013-01-01

Objectives This study aimed at developing a list of key human health indicators for quantifying the health impacts of climate change in Canada. Methods A literature review was conducted in OVID Medline to identify health morbidity and mortality indicators currently used to quantify climate change impacts. Public health frameworks and other studies of climate change indicators were reviewed to identify criteria with which to evaluate the list of proposed key indicators and a rating scale was d...

12 CFR 569.4 - Proxy soliciting material.

Science.gov (United States)

2010-01-01

... 12 Banks and Banking 5 2010-01-01 2010-01-01 false Proxy soliciting material. 569.4 Section 569.4 Banks and Banking OFFICE OF THRIFT SUPERVISION, DEPARTMENT OF THE TREASURY PROXIES § 569.4 Proxy soliciting material. No solicitation of a proxy shall be made by means of any statement, form of proxy...

Impact of climate change in Switzerland on socioeconomic snow indices

Science.gov (United States)

Schmucki, Edgar; Marty, Christoph; Fierz, Charles; Weingartner, Rolf; Lehning, Michael

2017-02-01

Snow is a key element for many socioeconomic activities in mountainous regions. Due to the sensitivity of the snow cover to variations of temperature and precipitation, major changes caused by climate change are expected to happen. We analyze the evolution of some key snow indices under future climatic conditions. Ten downscaled and postprocessed climate scenarios from the ENSEMBLES database have been used to feed the physics-based snow model SNOWPACK. The projected snow cover has been calculated for 11 stations representing the diverse climates found in Switzerland. For the first time, such a setup is used to reveal changes in frequently applied snow indices and their implications on various socioeconomic sectors. Toward the end of the twenty-first century, a continuous snow cover is likely only guaranteed at high elevations above 2000 m a.s.l., whereas at mid elevations (1000-1700 m a.s.l.), roughly 50 % of all winters might be characterized by an ephemeral snow cover. Low elevations (below 500 m a.s.l.) are projected to experience only 2 days with snowfall per year and show the strongest relative reductions in mean winter snow depth of around 90 %. The range of the mean relative reductions of the snow indices is dominated by uncertainties from different GCM-RCM projections and amounts to approximately 30 %. Despite these uncertainties, all snow indices show a clear decrease in all scenario periods and the relative reductions increase toward lower elevations. These strong reductions can serve as a basis for policy makers in the fields of tourism, ecology, and hydropower.

12 CFR 569.2 - Form of proxies.

Science.gov (United States)

2010-01-01

... 12 Banks and Banking 5 2010-01-01 2010-01-01 false Form of proxies. 569.2 Section 569.2 Banks and Banking OFFICE OF THRIFT SUPERVISION, DEPARTMENT OF THE TREASURY PROXIES § 569.2 Form of proxies. Every form of proxy shall conform to the following requirements: (a) The proxy shall be revocable at will by...

Quantifying the effect of seasonal and vertical habitat tracking on planktonic foraminifera proxies

Directory of Open Access Journals (Sweden)

L. Jonkers

2017-06-01

Full Text Available The composition of planktonic foraminiferal (PF calcite is routinely used to reconstruct climate variability. However, PF ecology leaves a large imprint on the proxy signal: seasonal and vertical habitats of PF species vary spatially, causing variable offsets from annual mean surface conditions recorded by sedimentary assemblages. PF seasonality changes with temperature in a way that minimises the environmental change that individual species experience and it is not unlikely that changes in depth habitat also result from such habitat tracking. While this behaviour could lead to an underestimation of spatial or temporal trends as well as of variability in proxy records, most palaeoceanographic studies are (implicitly based on the assumption of a constant habitat. Up to now, the effect of habitat tracking on foraminifera proxy records has not yet been formally quantified on a global scale. Here we attempt to characterise this effect on the amplitude of environmental change recorded in sedimentary PF using core top δ18O data from six species. We find that the offset from mean annual near-surface δ18O values varies with temperature, with PF δ18O indicating warmer than mean conditions in colder waters (on average by −0.1 ‰ (equivalent to 0.4 °C per °C, thus providing a first-order quantification of the degree of underestimation due to habitat tracking. We use an empirical model to estimate the contribution of seasonality to the observed difference between PF and annual mean δ18O and use the residual Δδ18O to assess trends in calcification depth. Our analysis indicates that given an observation-based model parametrisation calcification depth increases with temperature in all species and sensitivity analysis suggests that a temperature-related seasonal habitat adjustment is essential to explain the observed isotope signal. Habitat tracking can thus lead to a significant reduction in the amplitude of recorded environmental change

Pacific Islands Regional Climate Assessment: Building a Framework to Track Physical and Social Indicators of Climate Change Across Pacific Islands

Science.gov (United States)

Grecni, Z. N.; Keener, V. W.

2016-12-01

Assessments inform regional and local climate change governance and provide the critical scientific basis for U.S. climate policy. Despite the centrality of scientific information to public discourse and decision making, comprehensive assessments of climate change drivers, impacts, and the vulnerability of human and ecological systems at regional or local scales are often conducted on an ad hoc basis. Methods for sustained assessment and communication of scientific information are diverse and nascent. The Pacific Islands Regional Climate Assessment (PIRCA) is a collaborative effort to assess climate change indicators, impacts, and adaptive capacity of the Hawaiian archipelago and the US-Affiliated Pacific Islands (USAPI). In 2012, PIRCA released the first comprehensive report summarizing the state of scientific knowledge about climate change in the region as a technical input to the U.S. National Climate Assessment. A multi-method evaluation of PIRCA outputs and delivery revealed that the vast majority of key stakeholders view the report as extremely credible and use it as a resource. The current study will present PIRCA's approach to establishing physical and social indicators to track on an ongoing basis, starting with the Republic of the Marshall Islands as an initial location of focus for providing a cross-sectoral indicators framework. Identifying and tracking useful indicators is aimed at sustaining the process of knowledge coproduction with decision makers who seek to better understand the climate variability and change and its impacts on Pacific Island communities.

Precipitation extremes and their relation to climatic indices in the Pacific Northwest USA

Science.gov (United States)

Zarekarizi, Mahkameh; Rana, Arun; Moradkhani, Hamid

2018-06-01

There has been focus on the influence of climate indices on precipitation extremes in the literature. Current study presents the evaluation of the precipitation-based extremes in Columbia River Basin (CRB) in the Pacific Northwest USA. We first analyzed the precipitation-based extremes using statistically (ten GCMs) and dynamically downscaled (three GCMs) past and future climate projections. Seven precipitation-based indices that help inform about the flood duration/intensity are used. These indices help in attaining first-hand information on spatial and temporal scales for different service sectors including energy, agriculture, forestry etc. Evaluation of these indices is first performed in historical period (1971-2000) followed by analysis of their relation to large scale tele-connections. Further we mapped these indices over the area to evaluate the spatial variation of past and future extremes in downscaled and observational data. The analysis shows that high values of extreme indices are clustered in either western or northern parts of the basin for historical period whereas the northern part is experiencing higher degree of change in the indices for future scenario. The focus is also on evaluating the relation of these extreme indices to climate tele-connections in historical period to understand their relationship with extremes over CRB. Various climate indices are evaluated for their relationship using Principal Component Analysis (PCA) and Singular Value Decomposition (SVD). Results indicated that, out of 13 climate tele-connections used in the study, CRB is being most affected inversely by East Pacific (EP), Western Pacific (WP), East Atlantic (EA) and North Atlaentic Oscillation (NAO).

Ocean climate indicators: A monitoring inventory and plan for tracking climate change in the north-central California coast and ocean region

Science.gov (United States)

Duncan, Benet; Higgason, Kelley; Suchanek, Tom; Largier, John; Stachowicz, Jay; Allen, Sarah; Bograd, Steven; Breen, R.; Gellerman, Holly; Hill, Tessa; Jahncke, Jaime; Johnson, Rebecca L.; Lonhart, Steve I.; Morgan, Steven; Wilkerson, Frances; Roletto, Jan

2013-01-01

The impacts of climate change, defined as increasing atmospheric and oceanic carbon dioxide and associated increases in average global temperature and oceanic acidity, have been observed both globally and on regional scales, such as in the North-central California coast and ocean, a region that extends from Point Arena to Point Año Nuevo and includes the Pacific coastline of the San Francisco Bay Area. Because of the high economic and ecological value of the region’s marine environment, the Gulf of the Farallones National Marine Sanctuary (GFNMS) and other agencies and organizations have recognized the need to evaluate and plan for climate change impacts. Climate change indicators can be developed on global, regional, and site-specific spatial scales, and they provide information about the presence and potential impacts of climate change. While indicators exist for the nation and for the state of California as a whole, no system of ocean climate indicators exist that specifically consider the unique characteristics of the California coast and ocean region. To that end, GFNMS collaborated with over 50 regional, federal, and state natural resource managers, research scientists, and other partners to develop a set of 2 ocean climate indicators specific to this region. A smaller working group of 13 regional partners developed monitoring goals, objectives, strategies, and activities for the indicators and recommended selected species for biological indicators, resulting in the Ocean Climate Indicators Monitoring Inventory and Plan. The working group considered current knowledge of ongoing monitoring, feasibility of monitoring, costs, and logistics in selecting monitoring activities and selected species.

Validation and application of a death proxy in adult cancer patients.

Science.gov (United States)

Mealing, Nicole M; Dobbins, Timothy A; Pearson, Sallie-Anne

2012-07-01

PURPOSE: Fact of death is not always available on data sets used for pharmacoepidemiological research. Proxies may be an appropriate substitute in the absence of death data. The purposes of this study were to validate a proxy for death in adult cancer patients and to assess its performance when estimating survival in two cohorts of cancer patients. METHODS: We evaluated 30-, 60-, 90- and 180-day proxies overall and by cancer type using data from 12 394 Australian veterans with lung, colorectal, breast or prostate cancer. The proxy indicated death if the difference between the last dispensing record and the end of the observational period exceeded the proxy cutoff. We then compared actual survival to 90-day proxy estimates in a subset of 4090 veterans with 'full entitlements' for pharmaceutical items and in 3704 Australian women receiving trastuzumab for HER2+ metastatic breast cancer. RESULTS: The 90-day proxy was optimal with an overall sensitivity of 99.3% (95%CI: 98.4-99.7) and a specificity of 97.6% (95%CI: 91.8-99.4). These measures remained high when evaluated by cancer type and spread of disease. The application of the proxy using the most conservative date of death estimate (date of last dispensing) generally underestimated survival, with estimates up to 3 months shorter than survival based on fact of death. CONCLUSIONS: A 90-day death proxy is a robust substitute to identify death in a chronic population when fact of death is not available. The proxy is likely to be valid across a range of chronic diseases as it relies on the presence of 'regular' dispensing records for individual patients. Copyright © 2011 John Wiley & Sons, Ltd. Copyright © 2011 John Wiley & Sons, Ltd.

The dendroclimatic proxies from the northern Quebec taiga in the PAGES 2K network: recent advances and future developments.

Science.gov (United States)

Gennaretti, Fabio; Naulier, Maud; Arseneault, Dominique; Savard, Martine; Bégin, Christian; Boucher, Etienne; Bégin, Yves; Guiot, Joël

2016-04-01

Northeastern North America was historically underrepresented in the network of climate proxies used for climate reconstructions over the last two millennia. Indeed, in North America most high-resolution climate proxies are long tree-ring chronologies but, in Northeastern North America, these chronologies are highly challenging due to short tree longevity, high frequency and severity of wildfires and remoteness of many areas. Here, we will present the efforts accomplished during the last decade by our team in developing millennial-long tree-ring chronologies in the northern Quebec taiga. We sampled black spruce [Picea mariana (Mill.) B.S.P] subfossil tree remains naturally fallen in the littoral zone of six lakes to build six site-specific ring-width chronologies as well as two chronologies of stable isotope ratios (δ18O and δ13C in tree-ring cellulose). These chronologies, which are now included in the PAGES 2K network, were independently used to reconstruct summer temperature variations showing a well-expressed Medieval Climate Anomaly and the impact of volcanic and solar forcings at regional scale. We will also discuss non-climatic influences on these chronologies (i.e. wildfires and sampling height inconsistency), as well as the ongoing effort to extend the reconstructions in time to cover the last 2500 years. Finally, a new European funded project called MAIDEN-SPRUCE will be introduced. Within MAIDEN-SPRUCE, we will use a data-model approach to improve our understanding of the links between forests and climate over the last millennium. More specifically, we will adapt the process-based ecophysiological model MAIDENiso to investigate factors influencing the growth and underlying biogeochemical processes of black spruce. One of our objectives is to provide the first multi-proxy (ring widths and δ18O and δ13C in tree-ring cellulose) regional climate reconstruction in Eastern North America over the last millennium taking into account mechanistic rules

Chapter 7 - Climate effects on lichen indicators for nitrogen

Science.gov (United States)

Sarah Jovan

2014-01-01

The Lichen Communities Indicator is a sensitive indicator of forest health changes caused by air quality, climate change, and other stressors. To date, more than 8,000 epiphytic lichen surveys have been collected across the Nation by the Forest Inventory Analysis (FIA) and Forest Health Monitoring (FHM) Programs and their partners (table 7.1; Phelan and others 2012)....

A model validation framework for climate change projection and impact assessment

DEFF Research Database (Denmark)

Madsen, Henrik; Refsgaard, Jens C.; Andréassian, Vazken

2014-01-01

methods for projection of climate change (single and ensemble model projections and space‐timesubstitution) and use of different data sources as proxy for future climate conditions (long historical records comprising non‐ stationarity, paleo data, and controlled experiments). The basic guiding principles...... proxy data, reflecting future conditions. This test can be used with both single and ensemble model projections as well as with space‐time‐substitutions. It is generally expected to be more powerful when applied to a model ensemble than to a single model. Since space‐timesubstitutions include...... a differential split‐sample test using best available proxy data that reflect the expected future conditions at the site being considered. Such proxy data may be obtained from long historical records comprising nonstationarity, paleo data, or controlled experiments. The test can be applied with different...

El Niño impact on mollusk biomineralization-implications for trace element proxy reconstructions and the paleo-archeological record.

Directory of Open Access Journals (Sweden)

Alberto Pérez-Huerta

Full Text Available Marine macroinvertebrates are ideal sentinel organisms to monitor rapid environmental changes associated with climatic phenomena. These organisms build up protective exoskeletons incrementally by biologically-controlled mineralization, which is deeply rooted in long-term evolutionary processes. Recent studies relating potential rapid environmental fluctuations to climate change, such as ocean acidification, suggest modifications on carbonate biominerals of marine invertebrates. However, the influence of known, and recurrent, climatic events on these biological processes during active mineralization is still insufficiently understood. Analysis of Peruvian cockles from the 1982-83 large magnitude El Niño event shows significant alterations of the chemico-structure of carbonate biominerals. Here, we show that bivalves modify the main biomineralization mechanism during the event to continue shell secretion. As a result, magnesium content increases to stabilize amorphous calcium carbonate (ACC, inducing a rise in Mg/Ca unrelated to the associated increase in sea-surface temperature. Analysis of variations in Sr/Ca also suggests that this proxy should not be used in these bivalves to detect the temperature anomaly, while Ba/Ca peaks are recorded in shells in response to an increase in productivity, or dissolved barium in seawater, after the event. Presented data contribute to a better understanding of the effects of abrupt climate change on shell biomineralization, while also offering an alternative view of bivalve elemental proxy reconstructions. Furthermore, biomineralization changes in mollusk shells can be used as a novel potential proxy to provide a more nuanced historical record of El Niño and similar rapid environmental change events.

Simulating the Incorporation of Geochemical Proxies into Scleractinian Coral Skeletons: Effects of Different Environmental and Biological Factors and Implications for Paleo-reconstruction

Science.gov (United States)

Guo, W.

2017-12-01

Chemical and isotopic compositions of scleractinian coral skeletons reflect the physicochemical condition of the seawater in which corals grow. This makes coral skeleton one of the best archives of ocean climate and biogeochemical changes. A number of coral-based geochemical proxies have been developed and applied to reconstruct past seawater conditions, such as temperature, pH, carbonate chemistry and nutrient concentrations. Detailed laboratory and field-based studies of these proxies, however, indicate interpretation of the geochemistry of coral skeletons is not straightforward, due to the presence of `vital effects' and the variations of empirical proxy calibrations among and within different species. This poses challenges for the broad application of many geochemical proxies in corals, and highlights the need to better understand the fundamental processes governing the incorporation of different proxies. Here I present a numerical model that simulates the incorporation of a suite of geochemical proxies into coral skeletons, including δ11B, Mg/Ca, Sr/Ca, U/Ca, B/Ca and Ba/Ca. This model, building on previous theoretical studies of coral calcification, combines our current understanding of coral calcification mechanism with experimental constraints on the isotope and element partition during carbonate precipitation. It enables quantitative evaluation of the effects of different environmental and biological factors on each proxy. Specifically, this model shows that (1) the incorporation of every proxy is affected by multiple seawater parameters (e.g. temperature, pH, DIC) as opposed to one single parameter, and (2) biological factors, particularly the interplay between enzymatic alkalinity pumping and the exchange of coral calcifying fluid with external seawater, also exert significant controls. Based on these findings, I propose an inverse method for simultaneously reconstructing multiple seawater physicochemical parameters, and compare the performance of this

Indigenous community health and climate change: integrating biophysical and social science indicators

Science.gov (United States)

Donatuto, Jamie; Grossman, Eric E.; Konovsky, John; Grossman, Sarah; Campbell, Larry W.

2014-01-01

This article describes a pilot study evaluating the sensitivity of Indigenous community health to climate change impacts on Salish Sea shorelines (Washington State, United States and British Columbia, Canada). Current climate change assessments omit key community health concerns, which are vital to successful adaptation plans, particularly for Indigenous communities. Descriptive scaling techniques, employed in facilitated workshops with two Indigenous communities, tested the efficacy of ranking six key indicators of community health in relation to projected impacts to shellfish habitat and shoreline archaeological sites stemming from changes in the biophysical environment. Findings demonstrate that: when shellfish habitat and archaeological resources are impacted, so is Indigenous community health; not all community health indicators are equally impacted; and, the community health indicators of highest concern are not necessarily the same indicators most likely to be impacted. Based on the findings and feedback from community participants, exploratory trials were successful; Indigenous-specific health indicators may be useful to Indigenous communities who are assessing climate change sensitivities and creating adaptation plans.

Organic molecules in the polar ice: from chemical analysis to environmental proxies

Science.gov (United States)

Barbante, Carlo; Zennaro, Piero; Giorio, Chiara; Kehrwald, Natalie; Benton, Alisa K.; Wolff, Eric W.; Kalberer, Markus; Kirchgeorg, Torben; Zangrando, Roberta; Barbaro, Elena; Gambaro, Andrea

2015-04-01

The molecular and isotopic compositions of organic matter buried in ice contains information that helps reconstruct past environmental conditions, evaluate histories of climate change, and assess impacts of humans on ecosystems. In recent years novel analytical techniques were developed to quantify molecular compounds in ice cores. As an example, biomass burning markers, including monosaccharide anhydrides, lightweight carboxylic acids, lignin and resin pyrolysis products, black carbon, and charcoal records help in reconstructing past fire activity across seasonal to millennial time scales. Terrestrial biomarkers, such as plant waxes (e.g. long-chain n-alkanes) are also a promising paleo vegetation proxy in ice core studies. Polycyclic aromatic hydrocarbons are ubiquitous pollutants recently detected in ice cores. These hydrocarbons primarily originate from incomplete combustion of organic matter and fossil fuels (e.g. diesel engines, domestic heating, industrial combustion) and therefore can be tracers of past combustion activities. In order to be suitable for paloeclimate purposes, organic molecular markers detected in ice cores should include the following important features. Markers have to be stable under oxidizing atmospheric conditions, and ideally should not react with hydroxyl radicals, during their transport to polar regions. Organic markers must be released in large amounts in order to be detected at remote distances from the sources. Proxies must be specific, in order to differentiate them from other markers with multiple sources. The extraction of glaciochemical information from ice cores is challenging due to the low concentrations of some impurities, thereby demanding rigorous control of external contamination sources and sensitive analytical techniques. Here, we review the analysis and use of organic molecules in ice as proxies of important environmental and climatic processes.

Simulated trends of extreme climate indices for the Carpathian basin using outputs of different regional climate models

Science.gov (United States)

Pongracz, R.; Bartholy, J.; Szabo, P.; Pieczka, I.; Torma, C. S.

2009-04-01

Regional climatological effects of global warming may be recognized not only in shifts of mean temperature and precipitation, but in the frequency or intensity changes of different climate extremes. Several climate extreme indices are analyzed and compared for the Carpathian basin (located in Central/Eastern Europe) following the guidelines suggested by the joint WMO-CCl/CLIVAR Working Group on climate change detection. Our statistical trend analysis includes the evaluation of several extreme temperature and precipitation indices, e.g., the numbers of severe cold days, winter days, frost days, cold days, warm days, summer days, hot days, extremely hot days, cold nights, warm nights, the intra-annual extreme temperature range, the heat wave duration, the growing season length, the number of wet days (using several threshold values defining extremes), the maximum number of consecutive dry days, the highest 1-day precipitation amount, the greatest 5-day rainfall total, the annual fraction due to extreme precipitation events, etc. In order to evaluate the future trends (2071-2100) in the Carpathian basin, daily values of meteorological variables are obtained from the outputs of various regional climate model (RCM) experiments accomplished in the frame of the completed EU-project PRUDENCE (Prediction of Regional scenarios and Uncertainties for Defining EuropeaN Climate change risks and Effects). Horizontal resolution of the applied RCMs is 50 km. Both scenarios A2 and B2 are used to compare past and future trends of the extreme climate indices for the Carpathian basin. Furthermore, fine-resolution climate experiments of two additional RCMs adapted and run at the Department of Meteorology, Eotvos Lorand University are used to extend the trend analysis of climate extremes for the Carpathian basin. (1) Model PRECIS (run at 25 km horizontal resolution) was developed at the UK Met Office, Hadley Centre, and it uses the boundary conditions from the HadCM3 GCM. (2) Model Reg

Reliability of proxy respondents for patients with stroke: a systematic review.

Science.gov (United States)

Oczkowski, Colin; O'Donnell, Martin

2010-01-01

Proxy respondents are an important aspect of stroke medicine and research. We performed a systematic review of studies evaluating the reliability of proxy respondents for stroke patients. Studies were identified by searches of MEDLINE, Google, and the Cochrane Library between January 1969 and June 2008. All were prospective or cross-sectional studies reporting the reliability of proxy respondents for patients with a history of previous stroke or transient ischemic attack. One author abstracted data. For each study, intraclass correlation (ICC) or the k-statistic was categorized as poor (0.80). Thirteen studies, with a total of 2618 participants, met our inclusion criteria. Most studies recruited patients >3 months after their stroke. Of these studies, 5 (360 participants; 5 scales) evaluated reliability of proxy respondents for activities of daily living (ADL), and 9 (2334 participants; 9 scales) evaluated reliability of proxy respondents for quality of life (QoL). One study evaluated both. In studies, the ICC/k for scales ranged from 0.61 to 0.91 for ADL and from 0.41 to 0.8 for QoL. Most studies reported that proxy respondents overestimated impairments compared with patient self-reports. Stroke severity and objective nature of questions were the most consistent determinants of disagreement between stroke patient and proxy respondent. Our data indicate that beyond the acute stroke period, the reliability of proxy respondents for validated scales of ADL was substantial to excellent, while that of scales for QoL was moderate to substantial. Copyright (c) 2010 National Stroke Association. Published by Elsevier Inc. All rights reserved.

Shareholder Activism through the Proxy Process

NARCIS (Netherlands)

Renneboog, L.D.R.; Szilagyi, P.G.

2009-01-01

This paper provides evidence on the corporate governance role of shareholderinitiated proxy proposals. Previous studies debate over whether activists use proxy proposals to discipline firms or to simply advance their self-serving agendas, and whether proxy proposals are effective at all in

Shareholder Activism Through the Proxy Process

NARCIS (Netherlands)

Renneboog, L.D.R.; Szilagyi, P.G.

2009-01-01

This paper provides evidence on the corporate governance role of shareholder-initiated proxy proposals. Previous studies debate over whether activists use proxy proposals to discipline firms or to simply advance their self-serving agendas, and whether proxy proposals are effective at all in

Register of the last 1000 years of environmental, climatic and anthropogenic change in Isla Grande de Chiloé, inferred through a multi-proxy approach: Lake Pastahué, Chile-South Center (42°S)

Science.gov (United States)

Troncoso, Jose; Alvarez, Denisse; Díaz, Gustavo; Fierro, Pablo; Araneda, Alberto; Torrejón, Fernando; Rondanelli, Mauricio; Fagel, Nathalie; Urrutia, Roberto

2017-04-01

Knowledge of the past environmental and climatic conditions of the lake ecosystems of the Isla Grande de Chiloé and its relationship with the anthropic effect, on a high temporal resolution scale, is scarcely known. Specifically, multi-proxy studies provide a better understanding of the context in which changes occurred in the past. This insular region is particularly interesting because environmental conditions (pre and post-Hispanic) and knowledge about the impacts generated in the ecosystems during the Spanish colonization process have so far been little studied, compared to the rest of Chile continental. This research is a new contribution to the scarce information existing for the last millennium of the Isla Grande de Chiloé. The objective of this work was to reconstruct the environmental and climatic history of the last 1000 years, from the Lake Pastahué, in the Isla Grande de Chiloé through a multi-proxy analysis and compare them with other records for the region. The core sediment was sub-sampled to perform sedimentological analysis (organic matter, carbonates, magnetic susceptibility and granulometry) and biological indicators (pollen, chironomids). The age model was constructed from the activity of 210Pb,137Cs and 14C. The pollen results reveal a composition of nordpatagónico forest represented by Nothofagus, Weinmannia, Drimys, Tepualia, Myrtaceae, Poaceae and Pteridophyta, while the anthropic effect for the last cm of the profile is represented by Rumex and Pinus. The results show a significant increase in magnetic susceptibility since the middle of the 20th century, suggesting an increase in allochthonous material to the lake. The sedimentological parameters and the chironomid assembly show similar variations along the profile, which also shows changes in the trophic state of the lake. The changes recorded in lake Pastahue are directly related to past climatic phenomena occurring in the last millennium, such as the medieval climatic anomaly (MCA

Tropical Hydroclimate Change during Heinrich Stadial 1: An Integrative Proxy-Model Synthesis

Science.gov (United States)

Lawman, A. E.; Sun, T.; Shanahan, T. M.; Di Nezio, P. N.; Gomez, K.; Piatrunia, N.; Sun, C.; Wu, X.; Kageyama, M.; Merkel, U.; Otto-Bliesner, B. L.; Abe-Ouchi, A.; Lohmann, G.; Singarayer, J. S.

2017-12-01

We explore the response of tropical climate to abrupt cooling of the North Atlantic (NA) during Heinrich Stadial 1 (HS1) combining paleoclimate proxies with model simulations. A total of 146 published paleoclimate records from tropical locations are used to categorize whether HS1 was wetter, drier, or unchanged relative to a deglacial baseline state. Only records with sufficient resolution to resolve HS1 and sufficient length to characterize the deglacial trend are considered. This synthesis reveals large-scale patterns of hydroclimate change relative to glacial conditions, confirming previously reported weaker Indian summer monsoon, a wetter southern Africa, and drying over the Caribbean. Our synthesis also reveals large-scale drying over the Maritime continent as well as wetter conditions in northern Australia and southern tropical South America. Our reinterpretation of the available proxy data reveals far more complexity and uncertainties for equatorial East Africa, a region that appears to straddle a pattern of dryer conditions to the north and wetter conditions to the south. Overall, these patterns of hydroclimate change depart from a southward shift of the Inter Tropical Convergence Zone (ITCZ), particularly outside the tropical Atlantic. We explore mechanisms driving these changes using a multi-model ensemble of "hosing" simulations performed relative to glacial conditions. The models show robust weakening of the Afro-Asian Monsoon, which we attribute to ventilation of colder mid-latitude air. Not all models simulate the remaining patterns inferred from the proxy data. The best-agreeing models indicate that cooling over the tropical NA and the Caribbean may be essential to communicate the response to the global tropics. This response can induce warming over the tropical South Atlantic via the wind-evaporation-SST feedback, driving wetter conditions in South Africa and tropical South America. Cooling over the Caribbean is communicated to the Pacific over the

Wood anatomical parameters of lowland European oak and Scots pine as proxies for climate reconstructions

Science.gov (United States)

Balanzategui, Daniel; Heußner, Karl-Uwe; Wazny, Tomasz; Helle, Gerd; Heinrich, Ingo

2017-04-01

Tree-ring based temperature reconstructions from the temperate lowlands worldwide are largely missing due to diffuse climate signals so far found in tree-ring widths. This motivated us to concentrate our efforts on the wood anatomies of two common European tree species, the European oak (Quercus robur) and Scots pine (Pinus sylvestris). We combined core samples of living trees with archaeological wood from northern Germany and Poland. We measured approx. 46,000 earlywood oak vessels of 34 trees covering the period AD 1500 to 2016 and approx. 7.5 million pine tracheid cells of 41 trees covering the period AD 1300 to 2010. First climate growth analyses indicate that both oak earlywood vessel and pine tracheid parameters contain climate signals which are different and more significant than those found in tree-ring widths. Preliminary results will be presented and discussed at EGU for the first time.

Impact of the Little Ice Age cooling and 20th century climate change on peatland vegetation dynamics in central and northern Alberta using a multi-proxy approach and high-resolution peat chronologies

Science.gov (United States)

Magnan, Gabriel; van Bellen, Simon; Davies, Lauren; Froese, Duane; Garneau, Michelle; Mullan-Boudreau, Gillian; Zaccone, Claudio; Shotyk, William

2018-04-01

Northern boreal peatlands are major terrestrial sinks of organic carbon and these ecosystems, which are highly sensitive to human activities and climate change, act as sensitive archives of past environmental change at various timescales. This study aims at understanding how the climate changes of the last 1000 years have affected peatland vegetation dynamics in the boreal region of Alberta in western Canada. Peat cores were collected from five bogs in the Fort McMurray region (56-57° N), at the southern limit of sporadic permafrost, and two in central Alberta (53° N and 55° N) outside the present-day limit of permafrost peatlands. The past changes in vegetation communities were reconstructed using detailed plant macrofossil analyses combined with high-resolution peat chronologies (14C, atmospheric bomb-pulse 14C, 210Pb and cryptotephras). Peat humification proxies (C/N, H/C, bulk density) and records of pH and ash content were also used to improve the interpretation of climate-related vegetation changes. Our study shows important changes in peatland vegetation and physical and chemical peat properties during the Little Ice Age (LIA) cooling period mainly from around 1700 CE and the subsequent climate warming of the 20th century. In some bogs, the plant macrofossils have recorded periods of permafrost aggradation during the LIA with drier surface conditions, increased peat humification and high abundance of ericaceous shrubs and black spruce (Picea mariana). The subsequent permafrost thaw was characterized by a short-term shift towards wetter conditions (Sphagnum sect. Cuspidata) and a decline in Picea mariana. Finally, a shift to a dominance of Sphagnum sect. Acutifolia (mainly Sphagnum fuscum) occurred in all the bogs during the second half of the 20th century, indicating the establishment of dry ombrotrophic conditions under the recent warmer and drier climate conditions.

12 CFR 569.3 - Holders of proxies.

Science.gov (United States)

2010-01-01

... 12 Banks and Banking 5 2010-01-01 2010-01-01 false Holders of proxies. 569.3 Section 569.3 Banks and Banking OFFICE OF THRIFT SUPERVISION, DEPARTMENT OF THE TREASURY PROXIES § 569.3 Holders of proxies. No proxy of a mutual savings association with a term greater than eleven months or solicited at...

Utilizing the social media data to validate 'climate change' indices

Science.gov (United States)

Molodtsova, T.; Kirilenko, A.; Stepchenkova, S.

2013-12-01

Reporting the observed and modeled changes in climate to public requires the measures understandable by the general audience. E.g., the NASA GISS Common Sense Climate Index (Hansen et al., 1998) reports the change in climate based on six practically observable parameters such as the air temperature exceeding the norm by one standard deviation. The utility of the constructed indices for reporting climate change depends, however, on an assumption that the selected parameters are felt and connected with the changing climate by a non-expert, which needs to be validated. Dynamic discussion of climate change issues in social media may provide data for this validation. We connected the intensity of public discussion of climate change in social networks with regional weather variations for the territory of the USA. We collected the entire 2012 population of Twitter microblogging activity on climate change topic, accumulating over 1.8 million separate records (tweets) globally. We identified the geographic location of the tweets and associated the daily and weekly intensity of twitting with the following parameters of weather for these locations: temperature anomalies, 'hot' temperature anomalies, 'cold' temperature anomalies, heavy rain/snow events. To account for non-weather related events we included the articles on climate change from the 'prestige press', a collection of major newspapers. We found that the regional changes in parameters of weather significantly affect the number of tweets published on climate change. This effect, however, is short-lived and varies throughout the country. We found that in different locations different weather parameters had the most significant effect on climate change microblogging activity. Overall 'hot' temperature anomalies had significant influence on climate change twitting intensity.

Surface area changes of Himalayan ponds as a proxy of hydrological climate-driven fluctuations

Science.gov (United States)

Salerno, Franco; Thakuri, Sudeep; Guyennon, Nicolas; Viviano, Gaetano; Tartari, Gianni

2016-04-01

(glacial lake outburst floods). Whereas the lake surface areas variations of these lakes are strictly connected with the ablation processes and glacier velocities, variation related to unconnected glacial lakes are possibly influenced by only the resulting glacier melting. This difference with the other lake types makes unconnected glacial lakes potential indicators of changes of the main water balance components of high-elevated lake basins as: precipitation, glacier melting, and evapotranspiration. An evaluable opportunity for a fine-scale investigation on climate-driven fluctuations in lake surface area is particularly evident on the south slopes of Mt. Everest (Nepal), which is one of the most heavily glacierized parts of Himalaya, at same time, the region that is most characterized by glacial lakes in the overall Hindu-Kush-Himalaya range, and in which a twenty years series of temperature and precipitation has been recently reconstructed for high-elevations (5000 m a.s.l.). This contribution examines the surface area changes of unconnected glacial ponds, i.e., that are not directly connected with glaciers, on the south side of Mt. Everest in the last fifty years as part of an effort to evaluate if they can be considered potential indicators useful to detect how the climate is changed at high-elevations of the Himalayan range.

A Survey of the Relationship between Climatic Heat Stress Indices and Fundamental Milk Components Considering Uncertainty

Directory of Open Access Journals (Sweden)

Mohammad Reza Marami Milani

2015-11-01

Full Text Available The main purpose of this study is to assess the relationship between four bioclimatic indices for cattle (environmental stress, heat load, modified heat load, and respiratory rate predictor indices and three main milk components (fat, protein, and milk yield considering uncertainty. The climate parameters used to calculate the climate indices were taken from the NASA-Modern Era Retrospective-Analysis for Research and Applications (NASA-MERRA reanalysis from 2002 to 2010. Cow milk data were considered for the same period from April to September when the cows use the natural pasture. The study is based on a linear regression analysis using correlations as a summarizing diagnostic. Bootstrapping is used to represent uncertainty information in the confidence intervals. The main results identify an interesting relationship between the milk compounds and climate indices under all climate conditions. During spring, there are reasonably high correlations between the fat and protein concentrations vs. the climate indices, whereas there are insignificant dependencies between the milk yield and climate indices. During summer, the correlation between the fat and protein concentrations with the climate indices decreased in comparison with the spring results, whereas the correlation for the milk yield increased. This methodology is suggested for studies investigating the impacts of climate variability/change on food and agriculture using short term data considering uncertainty.

Earth's Climate History from Glaciers and Ice Cores

Science.gov (United States)

Thompson, Lonnie

2013-03-01

Glaciers serve both as recorders and early indicators of climate change. Over the past 35 years our research team has recovered climatic and environmental histories from ice cores drilled in both Polar Regions and from low to mid-latitude, high-elevation ice fields. Those ice core -derived proxy records extending back 25,000 years have made it possible to compare glacial stage conditions in the Tropics with those in the Polar Regions. High-resolution records of δ18O (in part a temperature proxy) demonstrate that the current warming at high elevations in the mid- to lower latitudes is unprecedented for the last two millennia, although at many sites the early Holocene was warmer than today. Remarkable similarities between changes in the highland and coastal cultures of Peru and regional climate variability, especially precipitation, imply a strong connection between prehistoric human activities and regional climate. Ice cores retrieved from shrinking glaciers around the world confirm their continuous existence for periods ranging from hundreds to thousands of years, suggesting that current climatological conditions in those regions today are different from those under which these ice fields originated and have been sustained. The ongoing widespread melting of high-elevation glaciers and ice caps, particularly in low to middle latitudes, provides strong evidence that a large-scale, pervasive and, in some cases, rapid change in Earth's climate system is underway. Observations of glacier shrinkage during the 20th and 21st century girdle the globe from the South American Andes, the Himalayas, Kilimanjaro (Tanzania, Africa) and glaciers near Puncak Jaya, Indonesia (New Guinea). The history and fate of these ice caps, told through the adventure, beauty and the scientific evidence from some of world's most remote mountain tops, provide a global perspective for contemporary climate. NSF Paleoclimate Program

Fire, Climate, and Human Activity: A Combustive Combination

Science.gov (United States)

Kehrwald, N. M.; Battistel, D.; Argiriadis, E.; Barbante, C.; Barber, L. B.; Fortner, S. K.; Jasmann, J.; Kirchgeorg, T.; Zennaro, P.

2017-12-01

Ice and lake core records demonstrate that fires caused by human activity can dominate regional biomass burning records in the Common Era. These major increases in fires are often associated with extensive land use change such as an expansion in agriculture. Regions with few humans, relatively stable human populations and/or unvarying land use often have fire histories that are dominated by climate parameters such as temperature and precipitation. Here, we examine biomass burning recorded in ice cores from northern Greenland (NEEM, (77°27'N; 51°3.6'W), Alaska (Juneau Icefield, 58° 35' N; 134° 29'W) and East Antarctica (EPICA DOME C; 75°06'S; 123°21'E), along with New Zealand lake cores to investigate interactions between climate, fire and human activity. Biomarkers such as levoglucosan, and its isomers mannosan and galactosan, can only be produced by cellulose combustion and therefore are specific indicators of past fire activity archived in ice and lake cores. These fire histories add another factor to climate proxies from the same core, and provide a comparison to regional fire syntheses from charcoal records and climate models. For example, fire data from the JSBACH-Spitfire model for the past 2000 years demonstrates that a climate-only scenario would not increase biomass burning in high northern latitudes for the past 2000 years, while NEEM ice core and regional pollen records demonstrate both increased fire activity and land use change that may be ascribed to human activity. Additional biomarkers such as fecal sterols in lake sediments can determine when people were in an area, and can help establish if an increased human presence in an area corresponds with intensified fire activity. This combination of specific biomarkers, other proxy data, and model output can help determine the relative impact of humans versus climate factors on regional fire activity.

Lichen communities as climate indicators in the U.S. Pacific States.

Science.gov (United States)

Robert J. Smith; Sarah Jovan; Bruce. McCune

2017-01-01

Epiphytic lichens are bioindicators of climate, air quality, and other forest conditions and may reveal how forests will respond to global changes in the U.S. Pacific States of Alaska, Washington, Oregon, and California. We explored climate indication with lichen communities surveyed by using both the USDA Forest Service Forest Inventory and Analysis (FIA) and Alaska...

Global Wildfire Forecasts Using Large Scale Climate Indices

Science.gov (United States)

Shen, Huizhong; Tao, Shu

2016-04-01

Using weather readings, fire early warning can provided forecast 4-6 hour in advance to minimize fire loss. The benefit would be dramatically enhanced if relatively accurate long-term projection can be also provided. Here we present a novel method for predicting global fire season severity (FSS) at least three months in advance using multiple large-scale climate indices (CIs). The predictive ability is proven effective for various geographic locations and resolution. Globally, as well as in most continents, the El Niño Southern Oscillation (ENSO) is the dominant driving force controlling interannual FSS variability, whereas other CIs also play indispensable roles. We found that a moderate El Niño event is responsible for 465 (272-658 as interquartile range) Tg carbon release and an annual increase of 29,500 (24,500-34,800) deaths from inhalation exposure to air pollutants. Southeast Asia accounts for half of the deaths. Both intercorrelation and interaction of WPs and CIs are revealed, suggesting possible climate-induced modification of fire responses to weather conditions. Our models can benefit fire management in response to climate change.

Performance of Solar Proxy Options of IRI-Plas Model for Equinox Seasons

Science.gov (United States)

Sezen, Umut; Gulyaeva, Tamara L.; Arikan, Feza

2018-02-01

International Reference Ionosphere (IRI) is the most acclaimed climatic model of the ionosphere. Since 2009, the range of the IRI model has been extended to the Global Positioning System (GPS) orbital height of 20,000 km in the plasmasphere. The new model, which is called IRI extended to Plasmasphere (IRI-Plas), can input not only the ionosonde foF2 and hmF2 but also the GPS-total electron content (TEC). IRI-Plas has been provided at www.ionolab.org, where online computation of ionospheric parameters is accomplished through a user-friendly interface. The solar proxies that are available in IRI-Plas can be listed as sunspot number (SSN1), SSN2, F10.7, global electron content (GEC), TEC, IG, Mg II, Lyman-α, and GEC_RZ. In this study, ionosonde foF2 data are compared with IRI-Plas foF2 values with the Consultative Committee International Radio (CCIR) and International Union of Radio Science (URSI) model choices for each solar proxy, with or without the GPS-TEC input for the equinox months of October 2011 and March 2015. It has been observed that the best fitting model choices in Root Mean Square (RMS) and Normalized RMS (NRMS) sense are the Jet Propulsion Laboratory global ionospheric maps-TEC input with Lyman-α solar proxy option for both months. The input of TEC definitely lowers the difference between the model and ionosonde foF2 values. The IG and Mg II solar proxies produce similar model foF2 values, and they usually are the second and third best fits to the ionosonde foF2 for the midlatitude ionosphere. In high-latitude regions, Jet Propulsion Laboratory global ionospheric map-TEC inputs to IRI-Plas with Lyman-α, GEC_RZ, and TEC solar proxies are the best choices. In equatorial region, the best fitting solar proxies are IG, Lyman-α, and Mg II.

Regionalizing indicators for marine ecosystems: Bering Sea–Aleutian Island seabirds, climate, and competitors

Science.gov (United States)

Sydeman, William J.; Thompson, Sarah Ann; Piatt, John F.; García-Reyes, Marisol; Zador, Stephani; Williams, Jeffrey C.; Romano, Marc; Renner, Heather

2017-01-01

Seabirds are thought to be reliable, real-time indicators of forage fish availability and the climatic and biotic factors affecting pelagic food webs in marine ecosystems. In this study, we tested the hypothesis that temporal trends and interannual variability in seabird indicators reflect simultaneously occurring bottom-up (climatic) and competitor (pink salmon) forcing of food webs. To test this hypothesis, we derived multivariate seabird indicators for the Bering Sea–Aleutian Island (BSAI) ecosystem and related them to physical and biological conditions known to affect pelagic food webs in the ecosystem. We examined covariance in the breeding biology of congeneric pelagic gulls (kittiwakes Rissa tridactyla and R. brevirostris) andauks (murres Uria aalge and U. lomvia), all of whichare abundant and well-studiedinthe BSAI. At the large ecosystem scale, kittiwake and murre breeding success and phenology (hatch dates) covaried among congeners, so data could be combined using multivariate techniques, but patterns of responsedifferedsubstantially betweenthe genera.Whiledata fromall sites (n = 5)inthe ecosystemcould be combined, the south eastern Bering Sea shelf colonies (St. George, St. Paul, and Cape Peirce) provided the strongest loadings on indicators, and hence had the strongest influence on modes of variability. The kittiwake breeding success mode of variability, dominated by biennial variation, was significantly related to both climatic factors and potential competitor interactions. The murre indicator mode was interannual and only weakly related to the climatic factors measured. The kittiwake phenology indicator mode of variability showed multi-year periods (“stanzas”) of late or early breeding, while the murre phenology indicator showed a trend towards earlier timing. Ocean climate relationships with the kittiwake breeding success indicator suggestthat early-season (winter–spring) environmental conditions and the abundance of pink salmon affect the

Indicators of Arctic Sea Ice Bistability in Climate Model Simulations and Observations

Science.gov (United States)

2014-09-30

associated with the ice - albedo feedback and the seasonal melt and growth of sea ice , as well as horizontal climate variations on a global domain. (2...1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Indicators of Arctic Sea Ice Bistability in Climate...possibility that the climate system supports multiple Arctic sea ice states that are relevant for the evolution of sea ice during the next several

Accounting for land use in life cycle assessment: The value of NPP as a proxy indicator to assess land use impacts on ecosystems.

Science.gov (United States)

Taelman, Sue Ellen; Schaubroeck, Thomas; De Meester, Steven; Boone, Lieselot; Dewulf, Jo

2016-04-15

Terrestrial land and its resources are finite, though, for economic and socio-cultural needs of humans, these natural resources are further exploited. It highlights the need to quantify the impact humans possibly have on the environment due to occupation and transformation of land. As a starting point of this paper (1(st) objective), the land use activities, which may be mainly socio-culturally or economically oriented, are identified in addition to the natural land-based processes and stocks and funds that can be altered due to land use. To quantify the possible impact anthropogenic land use can have on the natural environment, linked to a certain product or service, life cycle assessment (LCA) is a tool commonly used. During the last decades, many indicators are developed within the LCA framework in an attempt to evaluate certain environmental impacts of land use. A second objective of this study is to briefly review these indicators and to categorize them according to whether they assess a change in the asset of natural resources for production and consumption or a disturbance of certain ecosystem processes, i.e. ecosystem health. Based on these findings, two enhanced proxy indicators are proposed (3(rd) objective). Both indicators use net primary production (NPP) loss (potential NPP in the absence of humans minus remaining NPP after land use) as a relevant proxy to primarily assess the impact of land use on ecosystem health. As there are two approaches to account for the natural and productive value of the NPP remaining after land use, namely the Human Appropriation of NPP (HANPP) and hemeroby (or naturalness) concepts, two indicators are introduced and the advantages and limitations compared to state-of-the-art NPP-based land use indicators are discussed. Exergy-based spatially differentiated characterization factors (CFs) are calculated for several types of land use (e.g., pasture land, urban land). Copyright © 2016 Elsevier B.V. All rights reserved.

Subtask 2.4 - Integration and Synthesis in Climate Change Predictive Modeling

Energy Technology Data Exchange (ETDEWEB)

Jaroslav Solc

2009-06-01

The Energy & Environmental Research Center (EERC) completed a brief evaluation of the existing status of predictive modeling to assess options for integration of our previous paleohydrologic reconstructions and their synthesis with current global climate scenarios. Results of our research indicate that short-term data series available from modern instrumental records are not sufficient to reconstruct past hydrologic events or predict future ones. On the contrary, reconstruction of paleoclimate phenomena provided credible information on past climate cycles and confirmed their integration in the context of regional climate history is possible. Similarly to ice cores and other paleo proxies, acquired data represent an objective, credible tool for model calibration and validation of currently observed trends. It remains a subject of future research whether further refinement of our results and synthesis with regional and global climate observations could contribute to improvement and credibility of climate predictions on a regional and global scale.

Are fish outside their usual ranges early indicators of climate-driven range shifts?

Science.gov (United States)

Fogarty, Hannah E; Burrows, Michael T; Pecl, Gretta T; Robinson, Lucy M; Poloczanska, Elvira S

2017-05-01

Shifts in species ranges are a global phenomenon, well known to occur in response to a changing climate. New species arriving in an area may become pest species, modify ecosystem structure, or represent challenges or opportunities for fisheries and recreation. Early detection of range shifts and prompt implementation of any appropriate management strategies is therefore crucial. This study investigates whether 'first sightings' of marine species outside their normal ranges could provide an early warning of impending climate-driven range shifts. We examine the relationships between first sightings and marine regions defined by patterns of local climate velocities (calculated on a 50-year timescale), while also considering the distribution of observational effort (i.e. number of sampling days recorded with biological observations in global databases). The marine trajectory regions include climate 'source' regions (areas lacking connections to warmer areas), 'corridor' regions (areas where moving isotherms converge), and 'sink' regions (areas where isotherms locally disappear). Additionally, we investigate the latitudinal band in which first sightings were recorded, and species' thermal affiliations. We found that first sightings are more likely to occur in climate sink and 'divergent' regions (areas where many rapid and diverging climate trajectories pass through) indicating a role of temperature in driving changes in marine species distributions. The majority of our fish first sightings appear to be tropical and subtropical species moving towards high latitudes, as would be expected in climate warming. Our results indicate that first sightings are likely related to longer-term climatic processes, and therefore have potential use to indicate likely climate-driven range shifts. The development of an approach to detect impending range shifts at an early stage will allow resource managers and researchers to better manage opportunities resulting from range

Sphagnum-dwelling testate amoebae in subarctic bogs are more sensitive to soil warming in the growing season than in winter: the results of eight-year field climate manipulations.

NARCIS (Netherlands)

Tsyganov, A.N.; Aerts, R.; Nijs, I.; Cornelissen, J.H.C.; Beyens, L.

2012-01-01

Sphagnum-dwelling testate amoebae are widely used in paleoclimate reconstructions as a proxy for climate-induced changes in bogs. However, the sensitivity of proxies to seasonal climate components is an important issue when interpreting proxy records. Here, we studied the effects of summer warming,

Millennial- to century-scale variability in Gulf of Mexico Holocene climate records

Science.gov (United States)

Poore, R.Z.; Dowsett, H.J.; Verardo, S.; Quinn, T.M.

2003-01-01

Proxy records from two piston cores in the Gulf of Mexico (GOM) provide a detailed (50-100 year resolution) record of climate variability over the last 14,000 years. Long-term (millennial-scale) trends and changes are related to the transition from glacial to interglacial conditions and movement of the average position of the Intertropical Convergence Zone (ITCZ) related to orbital forcing. The ??18O of the surface-dwelling planktic foraminifer Globigerinoides ruber show negative excursions between 14 and 10.2 ka (radiocarbon years) that reflect influx of meltwater into the western GOM during melting of the Laurentide Ice Sheet. The relative abundance of the planktic foraminifer Globigerinoides sacculifer is related to transport of Caribbean water into the GOM. Maximum transport of Caribbean surface waters and moisture into the GOM associated with a northward migration of the average position of the ITCZ occurs between about 6.5 and 4.5 ka. In addition, abundance variations of G. sacculifer show century-scale variability throughout most of the Holocene. The GOM record is consistent with records from other areas, suggesting that century-scale variability is a pervasive feature of Holocene climate. The frequency of several cycles in the climate records is similar to cycles identified in proxy records of solar variability, indicating that at least some of the century-scale climate variability during the Holocene is due to external (solar) forcing.

Human activity and climate variability project: annual report 2001

International Nuclear Information System (INIS)

Harle, K.J.; Heijnis, H.; Henderson-Sellers, A.; Sharmeen, S.; Zahorowski, W.

2002-01-01

Knowledge of the state of the Australian environment, including natural climate variability, prior to colonial settlement is vital if we are to define and understand the impact of over two hundred years of post-industrial human activity on our landscape. ANSTO, in conjunction with university partners, is leading a major research effort to provide natural archives of human activity and climate variability over the last 500 years in Australia, utilising a variety of techniques, including lead-210 and radiocarbon dating and analyses of proxy indicators (such as microfossils) as well as direct evidence (such as trace elements) of human activity and climate variability. The other major project objectives were to contribute to the understanding of the impact of human induced and natural aerosols in the East Asian region on climate through analysis and sourcing of fine particles and characterisation of air samples using radon concentrations and to contribute to the improvement of land surface parameterisation schemes and investigate the potential to use stable isotopes to improve global climate models and thus improve our understanding of future climate

Spatial linkages between coral proxies of terrestrial runoff across a large embayment in Madagascar

Directory of Open Access Journals (Sweden)

C. A. Grove

2012-08-01

Full Text Available Coral cores provide vital climate reconstructions for site-specific temporal variability in river flow and sediment load. Yet, their ability to record spatial differences across multiple catchments is relatively unknown. Here, we investigate spatial linkages between four coral proxies of terrestrial runoff and their relationships between sites. Coral cores were drilled in and around Antongil Bay, the largest bay in Madagascar, and individually analysed for fifteen years of continuous luminescence (G / B, Ba / Ca, δ¹⁸O_sw and δ¹³C data. Each coral core was drilled close to individual river mouths (≥ 7 km, and proxy data were compared to modelled river discharge and sediment runoff data for the three corresponding catchments. A reasonable agreement between terrestrial runoff proxies with modelled river discharge and sediment yield was observed. Some inconsistencies between proxy and modelled data are likely linked to proxy behaviour, watershed size and local environmental physiochemical parameters. In general, the further a coral resided from its river source, the weaker the proxy relationship was with modelled data and other corals, due to mixing gradients and currents. Nevertheless, we demonstrate that two coral Ba / Ca and luminescence (G / B records influenced by the same watershed are reproducible. Furthermore, a strong Ba / Ca relationship was observed between two cores from distant watersheds, with baseline averages in agreement with modelled sediment runoff data. As humic acids behave conservatively in the water column, luminescence (G / B data gave the highest regional correlations between cores, and showed the most consistent relationship with site specific modelled discharge. No statistical relationship was observed between cores in terms of interannual δ¹⁸O_sw and δ¹³C, meaning corals were recording a localised signal at their respective sites, confounded by vital

Proxy records of Holocene storm events in coastal barrier systems: Storm-wave induced markers

Science.gov (United States)

Goslin, Jérôme; Clemmensen, Lars B.

2017-10-01

Extreme storm events in the coastal zone are one of the main forcing agents of short-term coastal system behavior. As such, storms represent a major threat to human activities concentrated along the coasts worldwide. In order to better understand the frequency of extreme events like storms, climate science must rely on longer-time records than the century-scale records of instrumental weather data. Proxy records of storm-wave or storm-wind induced activity in coastal barrier systems deposits have been widely used worldwide in recent years to document past storm events during the last millennia. This review provides a detailed state-of-the-art compilation of the proxies available from coastal barrier systems to reconstruct Holocene storm chronologies (paleotempestology). The present paper aims (I) to describe the erosional and depositional processes caused by storm-wave action in barrier and back-barrier systems (i.e. beach ridges, storm scarps and washover deposits), (ii) to understand how storm records can be extracted from barrier and back-barrier sedimentary bodies using stratigraphical, sedimentological, micro-paleontological and geochemical proxies and (iii) to show how to obtain chronological control on past storm events recorded in the sedimentary successions. The challenges that paleotempestology studies still face in the reconstruction of representative and reliable storm-chronologies using these various proxies are discussed, and future research prospects are outlined.

An astronomically-tuned climate framework for hominins in the Turkana Basin

NARCIS (Netherlands)

Joordens, J.C.A.; Vonhof, H.B.; Feibel, C.S.; Lourens, L.J.; Dupont-Nivet, G.; Lubbe, J.H.J.L. van der; Sier, M.J.; Davies, G.R.; Kroon, D.

2011-01-01

Understanding the influence of orbital climate cycles on hominin evolution remains a key challenge in paleoanthropology. The two major unresolved issues are: the absence of a climate proxy yielding high-resolution (< 20 kyr) terrestrial climate records, and the lack of age control on hominin fossil

Identification of relationships between climate indices and long-term precipitation in South Korea using ensemble empirical mode decomposition

Science.gov (United States)

Kim, Taereem; Shin, Ju-Young; Kim, Sunghun; Heo, Jun-Haeng

2018-02-01

Climate indices characterize climate systems and may identify important indicators for long-term precipitation, which are driven by climate interactions in atmosphere-ocean circulation. In this study, we investigated the climate indices that are effective indicators of long-term precipitation in South Korea, and examined their relationships based on statistical methods. Monthly total precipitation was collected from a total of 60 meteorological stations, and they were decomposed by ensemble empirical mode decomposition (EEMD) to identify the inherent oscillating patterns or cycles. Cross-correlation analysis and stepwise variable selection were employed to select the significant climate indices at each station. The climate indices that affect the monthly precipitation in South Korea were identified based on the selection frequencies of the selected indices at all stations. The NINO12 indices with four- and ten-month lags and AMO index with no lag were identified as indicators of monthly precipitation in South Korea. Moreover, they indicate meaningful physical information (e.g. periodic oscillations and long-term trend) inherent in the monthly precipitation. The NINO12 indices with four- and ten- month lags was a strong indicator representing periodic oscillations in monthly precipitation. In addition, the long-term trend of the monthly precipitation could be explained by the AMO index. A multiple linear regression model was constructed to investigate the influences of the identified climate indices on the prediction of monthly precipitation. Three identified climate indices successfully explained the monthly precipitation in the winter dry season. Compared to the monthly precipitation in coastal areas, the monthly precipitation in inland areas showed stronger correlation to the identified climate indices.

Past climate variability between 97 and 7 ka reconstructed from a multi proxy speleothem record from Western Cuba

Science.gov (United States)

Winterhalder, Sophie; Scholz, Denis; Mangini, Augusto; Spötl, Christoph; Jochum, Klaus Peter; Pajón, Jesús M.

2016-04-01

The tropical hydrological cycle plays a key role in regulating global climate, mainly through the export of heat and moisture to higher latitudes, and is highly sensitive to climate change, for instance due to changes in the position of the Intertropical Convergence Zone (ITCZ). Previous work on Caribbean stalagmites suggests a strong connection of precipitation variability to North Atlantic (NA) sea surface temperatures on multidecadal to millenial timescales (Fensterer et al., 2012; Fensterer et al., 2013; Winter et al., 2011). Cold phases in the NA potentially lead to a southward shift of the ITCZ and thus drier conditions in Cuba. On orbital timescales, Cuban stalagmites suggest a relation of speleothem δ18O values with the δ18O value of Caribbean surface waters (Fensterer et al., 2013). Here we present an expansion of the Cuban speleothem record covering the whole last glacial period from the end of MIS5c (97 ka BP) until 7 ka with hiatuses between 93-80 ka, 37-35 ka and 13-10 ka. Stalagmite Cuba medio (CM) has been precisely dated with 60 230Th/U-ages, mainly performed by the MC-ICPMS technique. The δ18O and δ13C records are completed by a continuous, high resolution LA-ICPMS trace element profile. These data allow for the first time to establish a multi-proxy climate reconstruction for the North Western Caribbean at decadal to centennial resolution for this period. The long-term variability of the δ18O values probably reflects rainfall amount in Cuba. The response to some Dansgaard/Oeschger and Heinrich stadials confirms the previously observed correlation between Caribbean and NA climate variability. However, this connection is not clearly imprinted throughout the record. Furthermore, trace elements, such as Mg, do not proof without ambiguity drier conditions in Cuba during NA cold events, such as the Heinrich stadials. This suggests that climate variability in Cuba was more complex during the last 100ka, and that the NA was not the only driving factor

Comparing children's GPS tracks with geospatial proxies for exposure to junk food.

Science.gov (United States)

Sadler, Richard C; Gilliland, Jason A

2015-01-01

Various geospatial techniques have been employed to estimate children's exposure to environmental cardiometabolic risk factors, including junk food. But many studies uncritically rely on exposure proxies which differ greatly from actual exposure. Misrepresentation of exposure by researchers could lead to poor decisions and ineffective policymaking. This study conducts a GIS-based analysis of GPS tracks--'activity spaces'--and 21 proxies for activity spaces (e.g. buffers, container approaches) for a sample of 526 children (ages 9-14) in London, Ontario, Canada. These measures are combined with a validated food environment database (including fast food and convenience stores) to create a series of junk food exposure estimates and quantify the errors resulting from use of different proxy methods. Results indicate that exposure proxies consistently underestimate exposure to junk foods by as much as 68%. This underestimation is important to policy development because children are exposed to more junk food than estimated using typical methods. Copyright © 2015 Elsevier Ltd. All rights reserved.

Regional projection of climate impact indices over the Mediterranean region

Science.gov (United States)

Casanueva, Ana; Frías, M.; Dolores; Herrera, Sixto; Bedia, Joaquín; San Martín, Daniel; Gutiérrez, José Manuel; Zaninovic, Ksenija

2014-05-01

Climate Impact Indices (CIIs) are being increasingly used in different socioeconomic sectors to transfer information about climate change impacts and risks to stakeholders. CIIs are typically based on different weather variables such as temperature, wind speed, precipitation or humidity and comprise, in a single index, the relevant meteorological information for the particular impact sector (in this study wildfires and tourism). This dependence on several climate variables poses important limitations to the application of statistical downscaling techniques, since physical consistency among variables is required in most cases to obtain reliable local projections. The present study assesses the suitability of the "direct" downscaling approach, in which the downscaling method is directly applied to the CII. In particular, for illustrative purposes, we consider two popular indices used in the wildfire and tourism sectors, the Fire Weather Index (FWI) and the Physiological Equivalent Temperature (PET), respectively. As an example, two case studies are analysed over two representative Mediterranean regions of interest for the EU CLIM-RUN project: continental Spain for the FWI and Croatia for the PET. Results obtained with this "direct" downscaling approach are similar to those found from the application of the statistical downscaling to the individual meteorological drivers prior to the index calculation ("component" downscaling) thus, a wider range of statistical downscaling methods could be used. As an illustration, future changes in both indices are projected by applying two direct statistical downscaling methods, analogs and linear regression, to the ECHAM5 model. Larger differences were found between the two direct statistical downscaling approaches than between the direct and the component approaches with a single downscaling method. While these examples focus on particular indices and Mediterranean regions of interest for CLIM-RUN stakeholders, the same study

Feasibility of high-density climate reconstruction based on Forest Inventory and Analysis (FIA) collected tree-ring data

Science.gov (United States)

R. Justin DeRose; Shih-Yu Wang; John D. Shaw

2013-01-01

This study introduces a novel tree-ring dataset, with unparalleled spatial density, for use as a climate proxy. Ancillary Douglas fir and pinyon pine tree-ring data collected by the U.S. Forest Service Forest Inventory and Analysis Program (FIA data) were subjected to a series of tests to determine their feasibility as climate proxies. First, temporal coherence between...

Pedo-chemical climate proxies in Late Pleistocene Serbian-Ukranian loess sequences

NARCIS (Netherlands)

Bokhorst, M.P.; Beets, C.J.; Markovic, S.B.; Gerasimenko, N.P.; Matviishina, Z.N.; Frechen, M.

2009-01-01

The last glacial-interglacial loess-paleosol sequences of Serbia and Ukraine provide a good climate reconstruction potential for this part of Europe. Four loess sections distributed over an area with present-day moist to semi-arid climates were studied. In addition to traditional paleoclimate

Witnessing entanglement by proxy

International Nuclear Information System (INIS)

Bäuml, Stefan; Bruß, Dagmar; Kampermann, Hermann; Huber, Marcus; Winter, Andreas

2016-01-01

Entanglement is a ubiquitous feature of low temperature systems and believed to be highly relevant for the dynamics of condensed matter properties and quantum computation even at higher temperatures. The experimental certification of this paradigmatic quantum effect in macroscopic high temperature systems is constrained by the limited access to the quantum state of the system. In this paper we show how macroscopic observables beyond the mean energy of the system can be exploited as proxy witnesses for entanglement detection. Using linear and semi-definite relaxations we show that all previous approaches to this problem can be outperformed by our proxies, i.e. entanglement can be certified at higher temperatures without access to any local observable. For an efficient computation of proxy witnesses one can resort to a generalised grand canonical ensemble, enabling entanglement certification even in complex systems with macroscopic particle numbers. (paper)

Epiphytes as an Indicator of Climate Change in Hawaii

Science.gov (United States)

Kettwich, S. K.

2013-12-01

Although climate change threatens many ecosystems, current research in this field suggests tropical vegetation lags in response. Epiphytes, or arboreal vegetation, occupy tight, climate-defined niches compared with co-occurring life forms such as trees, yet there have been few studies of Hawaii's epiphyte communities. Because of Hawaii Island's natural climatic diversity, it is an ideal location to understand how these intrinsically climate sensitive plants interact with the atmosphere and evaluate how they may serve as a near-term indicator of climate change. Here we establish a baseline from which changes in corticolous epiphyte communities can be monitored as a leading indicator of likely forest changes by 1) investigating patterns of epiphyte abundance and species composition across elevation and precipitation gradients on windward Hawaii Island, and 2) using physiological measurements to investigate the relative importance of rain vs. fog in epiphyte-atmosphere interactions. The precipitation gradient keeps elevation constant at 1000m, while varying precipitation between 2,400 and 6,400 mm/year. The elevation gradient keeps rainfall constant at 3000mm/year, and varies elevation between 200 and 1750 m. Forest sites are dominated by Ohia Lehua (Metrosideros polymorpha) across broad geographic and climatological ranges thus allowing examination of epiphytes on this single host. We quantified bryophytes and vascular plants growing on Ohia trunks with standardized diameter and branching characteristics. Overall, epiphyte communities showed much finer scale responses to climate variation when compared with structurally dominant vegetation (which was broadly similar at all sites). The precipitation gradient exhibits a clear increase in abundance of all epiphyte groups and a definable increase in diversity with increasing rainfall. Results across the elevation gradient show a higher abundance of filmy ferns and bryophytes above the lifting condensation level (about

Understanding the Cognitive and Affective Mechanisms that Underlie Proxy Risk Perceptions among Caregivers of Asthmatic Children.

Science.gov (United States)

Shepperd, James A; Lipsey, Nikolette P; Pachur, Thorsten; Waters, Erika A

2018-07-01

Medical decisions made on behalf of another person-particularly those made by adult caregivers for their minor children-are often informed by the decision maker's beliefs about the treatment's risks and benefits. However, we know little about the cognitive and affective mechanisms influencing such "proxy" risk perceptions and about how proxy risk perceptions are related to prominent judgment phenomena. Adult caregivers of minor children with asthma ( N = 132) completed an online, cross-sectional survey assessing 1) cognitions and affects that form the basis of the availability, representativeness, and affect heuristics; 2) endorsement of the absent-exempt and the better-than-average effect; and 3) proxy perceived risk and unrealistic comparative optimism of an asthma exacerbation. We used the Pediatric Asthma Control and Communication Instrument (PACCI) to assess asthma severity. Respondents with higher scores on availability, representativeness, and negative affect indicated higher proxy risk perceptions and (for representativeness only) lower unrealistic optimism, irrespective of asthma severity. Conversely, respondents who showed a stronger display of the better-than-average effect indicated lower proxy risk perceptions but did not differ in unrealistic optimism. The absent-exempt effect was unrelated to proxy risk perceptions and unrealistic optimism. Heuristic judgment processes appear to contribute to caregivers' proxy risk perceptions of their child's asthma exacerbation risk. Moreover, the display of other, possibly erroneous, judgment phenomena is associated with lower caregiver risk perceptions. Designing interventions that target these mechanisms may help caregivers work with their children to reduce exacerbation risk.

Potential climatic mechanisms associated with the mega drought at 4200 cal yr BP: linking proxy data with modern climate analogues

Science.gov (United States)

Carter, V.; Shinker, J. J.

2017-12-01

Roughly 4200 years ago, a 150-year long mega drought occurred in the central Rocky Mountains, as indicated by pollen evidence from lake sediments from Long Lake, south-eastern Wyoming. However, pollen evidence does not record the climate mechanisms that caused the drought; they only provide evidence that the drought occurred. A modern climate analogue technique using North American Regional Reanalysis data was applied to the sedimentary data in order to identify possible synoptic and dynamic patterns that may have caused the mega drought at 4200 cal yr BP. Our results suggest warm and dry conditions were a result of anomalously higher-than-normal geopotential heights that were centred over the Great Plains beginning in the spring and persisting through the fall. Drought conditions during the growing seasons was the result of the anomalous high-pressure ridge, which suppressed moisture transport via the low level jet from the Gulf of Mexico, as well as brought in dry continental air from in the interior region of North America. The conditions associated with modern analogues offer a potential climate mechanism that caused the mega drought 4200 years ago, and likely led to the changes in vegetation composition as evidenced by the pollen record from Long Lake, Wyoming.

Evaluating climate change mitigation potential of hydrochars: compounding insights from three different indicators

DEFF Research Database (Denmark)

Owsianiak, Mikołaj; Brooks, Jennifer; Renz, Michael

2017-01-01

beet, fava bean, onion and lucerne) and two different countries (Spain and Germany), and used three different indicators of climate change: global warming potential (GWP), global temperature change potential (GTP), and climate tipping potential (CTP). We found that although climate change benefits (GWP......) from just sequestration and temporary storage of carbon are sufficient to outweigh impacts stemming from hydrochar production and transportation to the field, even greater benefits stem from replacing climate-inefficient biowaste management treatment options, like composting in Spain. By contrast...

Development of ecological indicators of climate change based on lichen functional diversity

OpenAIRE

Matos, Paula Sofia Antunes

2016-01-01

Growing evidence shows us that climate has changed in the recent decades, and the scenario for the future will most likely worsen. A set of climate variables is being developed to monitor climate change, but this is not enough to keep track its effects on ecosystems. It’s imperative to understand and quantify how ecosystems functioning are affected by and respond to these changes, and ecological indicators based on biodiversity metrics are one of the tools to do this. The...

Collaborative Project: Development of an Isotope-Enabled CESM for Testing Abrupt Climate Changes

Energy Technology Data Exchange (ETDEWEB)

Liu, Zhengyu [Univ. of Wisconsin, Madison, WI (United States). Dept. of Atmospheric and Oceanic Sciences

2018-01-24

One of the most important validations for a state-of-art Earth System Model (ESM) with respect to climate changes is the simulation of the climate evolution and abrupt climate change events in the Earth’s history of the last 21,000 years. However, one great challenge for model validation is that ESMs usually do not directly simulate geochemical variables that can be compared directly with past proxy records. In this proposal, we have met this challenge by developing the simulation capability of major isotopes in a state-of-art ESM, the Community Earth System Model (CESM), enabling us to make direct model-data comparison by comparing the model directly against proxy climate records. Our isotope-enabled ESM incorporates the capability of simulating key isotopes and geotracers, notably δ¹⁸O, δD, δ¹⁴C, and δ¹³C, Nd and Pa/Th. The isotope-enabled ESM have been used to perform some simulations for the last 21000 years. The direct comparison of these simulations with proxy records has shed light on the mechanisms of important climate change events.

The climate continuum revisited

Science.gov (United States)

Emile-Geay, J.; Wang, J.; Partin, J. W.

2015-12-01

A grand challenge of climate science is to quantify the extent of natural variability on adaptation-relevant timescales (10-100y). Since the instrumental record is too short to adequately estimate the spectra of climate measures, this information must be derived from paleoclimate proxies, which may harbor a many-to-one, non-linear (e.g. thresholded) and non-stationary relationship to climate. In this talk, I will touch upon the estimation of climate scaling behavior from climate proxies. Two case studies will be presented: an investigation of scaling behavior in a reconstruction of global surface temperature using state-of- the-art data [PAGES2K Consortium, in prep] and methods [Guillot et al., 2015]. Estimating the scaling exponent β in spectra derived from this reconstruction, we find that 0 long-term memory. Overall, the reconstruction-based spectra are steeper than the ones based on an instrumental dataset [HadCRUT4.2, Morice et al., 2012], and those estimated from PMIP3/CMIP5 models, suggesting the climate system is more energetic at multidecadal to centennial timescales than can be inferred from the short instrumental record or from the models developed to reproduce it [Laepple and Huybers, 2014]. an investigation of scaling behavior in speleothems records of tropical hydroclimate. We will make use of recent advances in proxy system modeling [Dee et al., 2015] and investigate how various aspects of the speleothem system (karst dynamics, age uncertainties) may conspire to bias the estimate of scaling behavior from speleothem timeseries. The results suggest that ignoring such complications leads to erroneous inferences about hydroclimate scaling. References Dee, S. G., J. Emile-Geay, M. N. Evans, Allam, A., D. M. Thompson, and E. J. Steig (2015), J. Adv. Mod. Earth Sys., 07, doi:10.1002/2015MS000447. Guillot, D., B. Rajaratnam, and J. Emile-Geay (2015), Ann. Applied. Statist., pp. 324-352, doi:10.1214/14-AOAS794. Laepple, T., and P. Huybers (2014), PNAS, doi

Holocene Glacier Fluctuations in the Peruvian Andes Indicate Northern Climate Linkages

Science.gov (United States)

Licciardi, Joseph M.; Schaefer, Joerg M.; Taggart, Jean R.; Lund, David C.

2009-09-01

The role of the tropics in triggering, transmitting, and amplifying interhemispheric climate signals remains a key debate in paleoclimatology. Tropical glacier fluctuations provide important insight on regional paleoclimatic trends and forcings, but robust chronologies are scarce. Here, we report precise moraine ages from the Cordillera Vilcabamba (13°20‧S) of southern Peru that indicate prominent glacial events and associated climatic shifts in the outer tropics during the early Holocene and late in the “Little Ice Age” period. Our glacier chronologies differ from the New Zealand record but are broadly correlative with well-dated glacial records in Europe, suggesting climate linkages between the tropics and the North Atlantic region.

North Atlantic ocean circulation and abrupt climate change during the last glaciation.

Science.gov (United States)

Henry, L G; McManus, J F; Curry, W B; Roberts, N L; Piotrowski, A M; Keigwin, L D

2016-07-29

The most recent ice age was characterized by rapid and hemispherically asynchronous climate oscillations, whose origin remains unresolved. Variations in oceanic meridional heat transport may contribute to these repeated climate changes, which were most pronounced during marine isotope stage 3, the glacial interval 25 thousand to 60 thousand years ago. We examined climate and ocean circulation proxies throughout this interval at high resolution in a deep North Atlantic sediment core, combining the kinematic tracer protactinium/thorium (Pa/Th) with the deep water-mass tracer, epibenthic δ(13)C. These indicators suggest reduced Atlantic overturning circulation during every cool northern stadial, with the greatest reductions during episodic Hudson Strait iceberg discharges, while sharp northern warming followed reinvigorated overturning. These results provide direct evidence for the ocean's persistent, central role in abrupt glacial climate change. Copyright © 2016, American Association for the Advancement of Science.

CLIMATE CHANGE: LONG-TERM TRENDS AND SHORT-TERM OSCILLATIONS

Institute of Scientific and Technical Information of China (English)

GAO Xin-quan; ZHANG Xin; QIAN Wei-hong

2006-01-01

Identifying the Northern Hemisphere (NH) temperature reconstruction and instrumental data for the past 1000 years shows that climate change in the last millennium includes long-term trends and various oscillations. Two long-term trends and the quasi-70-year oscillation were detected in the global temperature series for the last 140 years and the NH millennium series. One important feature was emphasized that temperature decreases slowly but it increases rapidly based on the analysis of different series. Benefits can be obtained of climate change from understanding various long-term trends and oscillations. Millennial temperature proxies from the natural climate system and time series of nonlinear model system are used in understanding the natural climate change and recognizing potential benefits by using the method of wavelet transform analysis. The results from numerical modeling show that major oscillations contained in numerical solutions on the interdecadal timescale are consistent with that of natural proxies. It seems that these oscillations in the climate change are not directly linked with the solar radiation as an external forcing. This investigation may conclude that the climate variability at the interdecadal timescale strongly depends on the internal nonlinear effects in the climate system.

Evaluation of CORDEX-Arctic daily precipitation and temperature-based climate indices over Canadian Arctic land areas

Science.gov (United States)

Diaconescu, Emilia Paula; Mailhot, Alain; Brown, Ross; Chaumont, Diane

2018-03-01

This study focuses on the evaluation of daily precipitation and temperature climate indices and extremes simulated by an ensemble of 12 Regional Climate Model (RCM) simulations from the ARCTIC-CORDEX experiment with surface observations in the Canadian Arctic from the Adjusted Historical Canadian Climate Dataset. Five global reanalyses products (ERA-Interim, JRA55, MERRA, CFSR and GMFD) are also included in the evaluation to assess their potential for RCM evaluation in data sparse regions. The study evaluated the means and annual anomaly distributions of indices over the 1980-2004 dataset overlap period. The results showed that RCM and reanalysis performance varied with the climate variables being evaluated. Most RCMs and reanalyses were able to simulate well climate indices related to mean air temperature and hot extremes over most of the Canadian Arctic, with the exception of the Yukon region where models displayed the largest biases related to topographic effects. Overall performance was generally poor for indices related to cold extremes. Likewise, only a few RCM simulations and reanalyses were able to provide realistic simulations of precipitation extreme indicators. The multi-reanalysis ensemble provided superior results to individual datasets for climate indicators related to mean air temperature and hot extremes, but not for other indicators. These results support the use of reanalyses as reference datasets for the evaluation of RCM mean air temperature and hot extremes over northern Canada, but not for cold extremes and precipitation indices.

Application and Network-Cognizant Proxies - Final Report

Energy Technology Data Exchange (ETDEWEB)

Antonio Ortega; Daniel C. Lee

2003-03-24

OAK B264 Application and Network-Cognizant Proxies - Final Report. Current networks show increasing heterogeneity both in terms of their bandwidths/delays and the applications they are required to support. This is a trend that is likely to intensify in the future, as real-time services, such as video, become more widely available and networking access over wireless links becomes more widespread. For this reason they propose that application-specific proxies, intermediate network nodes that broker the interactions between server and client, will become an increasingly important network element. These proxies will allow adaptation to changes in network characteristics without requiring a direct intervention of either server or client. Moreover, it will be possible to locate these proxies strategically at those points where a mismatch occurs between subdomains (for example, a proxy could be placed so as to act as a bridge between a reliable network domain and an unreliable one). This design philosophy favors scalability in the sense that the basic network infrastructure can remain unchanged while new functionality can be added to proxies, as required by the applications. While proxies can perform numerous generic functions, such as caching or security, they concentrate here on media-specific, and in particular video-specific, tasks. The goal of this project was to demonstrate that application- and network-specific knowledge at a proxy can improve overall performance especially under changing network conditions. They summarize below the work performed to address these issues. Particular effort was spent in studying caching techniques and on video classification to enable DiffServ delivery. other work included analysis of traffic characteristics, optimized media scheduling, coding techniques based on multiple description coding, and use of proxies to reduce computation costs. This work covered much of what was originally proposed but with a necessarily reduced scope.

Web proxy auto discovery for the WLCG

CERN Document Server

Dykstra, D; Blumenfeld, B; De Salvo, A; Dewhurst, A; Verguilov, V

2017-01-01

All four of the LHC experiments depend on web proxies (that is, squids) at each grid site to support software distribution by the CernVM FileSystem (CVMFS). CMS and ATLAS also use web proxies for conditions data distributed through the Frontier Distributed Database caching system. ATLAS & CMS each have their own methods for their grid jobs to find out which web proxies to use for Frontier at each site, and CVMFS has a third method. Those diverse methods limit usability and flexibility, particularly for opportunistic use cases, where an experiment’s jobs are run at sites that do not primarily support that experiment. This paper describes a new Worldwide LHC Computing Grid (WLCG) system for discovering the addresses of web proxies. The system is based on an internet standard called Web Proxy Auto Discovery (WPAD). WPAD is in turn based on another standard called Proxy Auto Configuration (PAC). Both the Frontier and CVMFS clients support this standard. The input into the WLCG system comes from squids regis...

Assessing the quality of life of children with sickle cell anaemia using self-, parent-proxy, and health care professional-proxy reports.

Science.gov (United States)

Constantinou, Christina; Payne, Nicola; Inusa, Baba

2015-05-01

The quality of life (QoL) of children with sickle cell anaemia (SCA) in the United Kingdom has not been examined, and a discrepancy measure based on Gap theory has rarely been used. This study investigated whether (1) child self-reports of QoL using a discrepancy measure (the Generic Children's QoL Measure; GCQ) are lower than those from healthy children, (2) proxy reports from parents and health care professionals are lower than child self-reports, and (3) demographic and disease severity indicators are related to QoL. An interdependent groups, cross-sectional design was implemented. Seventy-four children with SCA, their parent, and members of their health care team completed the GCQ. Demographic and disease severity indicators were recorded. GCQ data from healthy children were obtained from the UK Data Archive. Contrary to past research, when examining generic discrepancy QoL, children with SCA did not report a lower QoL than healthy children, and parent- and health care professional-proxy reports were not lower than child self-reports. Few of the demographic and disease severity indicators were related to QoL. Proxy reports may be used to gain a more complete picture of QoL, but should not be a substitute for self-reports. The explanation for the relatively high levels of QoL reported is not clear, but children with SCA may have realistic expectations about their ideal-self, place greater emphasis on aspects other than health in shaping their QoL, and define achievements within the limits of their illness. Future research should focus on psychological factors in explaining QoL. Statement of contribution What is already known on this subject? Children with sickle cell disease (SCD) generally have a reduced QoL compared with healthy children, but there appears to be no research measuring QoL in paediatric SCD in the United Kingdom. Proxy QoL reports from parents are often lower than child self-reports, but there is less research examining proxy reports from health

Multi-proxy reconstructions of May–September precipitation field in China over the past 500 years

Directory of Open Access Journals (Sweden)

F. Shi

2017-12-01

Full Text Available The dominant modes of variability of precipitation for the whole of China over the past millennium and the mechanism governing their spatial structure remain unclear. This is mainly due to insufficient high-resolution proxy records of precipitation in western China. Numerous tree-ring chronologies have recently been archived in publicly available databases through PAGES2k activities, and these provide an opportunity to refine precipitation field reconstructions for China. Based on 479 proxy records, including 371 tree-ring width chronologies, a tree-ring isotope chronology, and 107 drought/flood indices, we reconstruct the precipitation field for China for the past half millennium using the optimal information extraction method. A total of 3631 of 4189 grid points in the reconstruction field passed the cross-validation process, accounting for 86.68 % of the total number of grid points. The first leading mode of variability of the reconstruction shows coherent variations over most of China. The second mode is a north–south dipole in eastern China characterized by variations of the same sign in western China and northern China (except for Xinjiang province. It is likely controlled by the El Niño–Southern Oscillation (ENSO variability. The third mode is a sandwich triple mode in eastern China including variations of the same sign in western China and central China. The last two modes are reproduced by most of the six coupled climate models' last millennium simulations performed in the framework of the Paleoclimate Modelling Intercomparison Project Phase III (PMIP3. In particular, the link of the second mode with ENSO is confirmed by the models. However, there is a mismatch between models and proxy reconstructions in the time development of different modes. This mismatch suggests the important role of internal variability in the reconstructed precipitation mode variations of the past 500 years.

Multi-proxy reconstructions of May-September precipitation field in China over the past 500 years

Science.gov (United States)

Shi, Feng; Zhao, Sen; Guo, Zhengtang; Goosse, Hugues; Yin, Qiuzhen

2017-12-01

The dominant modes of variability of precipitation for the whole of China over the past millennium and the mechanism governing their spatial structure remain unclear. This is mainly due to insufficient high-resolution proxy records of precipitation in western China. Numerous tree-ring chronologies have recently been archived in publicly available databases through PAGES2k activities, and these provide an opportunity to refine precipitation field reconstructions for China. Based on 479 proxy records, including 371 tree-ring width chronologies, a tree-ring isotope chronology, and 107 drought/flood indices, we reconstruct the precipitation field for China for the past half millennium using the optimal information extraction method. A total of 3631 of 4189 grid points in the reconstruction field passed the cross-validation process, accounting for 86.68 % of the total number of grid points. The first leading mode of variability of the reconstruction shows coherent variations over most of China. The second mode is a north-south dipole in eastern China characterized by variations of the same sign in western China and northern China (except for Xinjiang province). It is likely controlled by the El Niño-Southern Oscillation (ENSO) variability. The third mode is a sandwich triple mode in eastern China including variations of the same sign in western China and central China. The last two modes are reproduced by most of the six coupled climate models' last millennium simulations performed in the framework of the Paleoclimate Modelling Intercomparison Project Phase III (PMIP3). In particular, the link of the second mode with ENSO is confirmed by the models. However, there is a mismatch between models and proxy reconstructions in the time development of different modes. This mismatch suggests the important role of internal variability in the reconstructed precipitation mode variations of the past 500 years.

Anthropogenic climate change has altered primary productivity in Lake Superior.

Science.gov (United States)

O'Beirne, M D; Werne, J P; Hecky, R E; Johnson, T C; Katsev, S; Reavie, E D

2017-06-09

Anthropogenic climate change has the potential to alter many facets of Earth's freshwater resources, especially lacustrine ecosystems. The effects of anthropogenic changes in Lake Superior, which is Earth's largest freshwater lake by area, are not well documented (spatially or temporally) and predicted future states in response to climate change vary. Here we show that Lake Superior experienced a slow, steady increase in production throughout the Holocene using (paleo)productivity proxies in lacustrine sediments to reconstruct past changes in primary production. Furthermore, data from the last century indicate a rapid increase in primary production, which we attribute to increasing surface water temperatures and longer seasonal stratification related to longer ice-free periods in Lake Superior due to anthropogenic climate warming. These observations demonstrate that anthropogenic effects have become a prominent influence on one of Earth's largest, most pristine lacustrine ecosystems.

Orbital Forcing driving climate variability on Tropical South Atlantic

Science.gov (United States)

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

2017-12-01

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

Coral Records of 20th Century Central Tropical Pacific SST and Salinity: Signatures of Natural and Anthropogenic Climate Change

Science.gov (United States)

Nurhati, I. S.; Cobb, K.; Di Lorenzo, E.

2011-12-01

Accurate forecasts of regional climate changes in many regions of the world largely depend on quantifying anthropogenic trends in tropical Pacific climate against its rich background of interannual to decadal-scale climate variability. However, the strong natural climate variability combined with limited instrumental climate datasets have obscured potential anthropogenic climate signals in the region. Here, we present coral-based sea-surface temperature (SST) and salinity proxy records over the 20th century (1898-1998) from the central tropical Pacific - a region sensitive to El Niño-Southern Oscillation (ENSO) whose variability strongly impacts the global climate. The SST and salinity proxy records are reconstructed via coral Sr/Ca and the oxygen isotopic composition of seawater (δ18Osw), respectively. On interannual (2-7yr) timescales, the SST proxy record tracks both eastern- and central-Pacific flavors of ENSO variability (R=0.65 and R=0.67, respectively). Interannual-scale salinity variability in our coral record highlights profound differences in precipitation and ocean advections during the two flavors of ENSO. On decadal (8yr-lowpassed) timescales, the central tropical Pacific SST and salinity proxy records are controlled by different sets of dynamics linked to the leading climate modes of North Pacific climate variability. Decadal-scale central tropical Pacific SST is highly correlated to the recently discovered North Pacific Gyre Oscillation (NPGO; R=-0.85), reflecting strong dynamical links between the central Pacific warming mode and extratropical decadal climate variability. Whereas decadal-scale salinity variations in the central tropical Pacific are significantly correlated with the Pacific Decadal Oscillation (PDO; R=0.54), providing a better understanding on low-frequency salinity variability in the region. Having characterized natural climate variability in this region, the coral record shows a +0.5°C warming trend throughout the last century

Estimates of late Cenozoic climate change relevant to Earth surface processes in tectonically active orogens

Science.gov (United States)

Mutz, Sebastian G.; Ehlers, Todd A.; Werner, Martin; Lohmann, Gerrit; Stepanek, Christian; Li, Jingmin

2018-04-01

The denudation history of active orogens is often interpreted in the context of modern climate gradients. Here we address the validity of this approach and ask what are the spatial and temporal variations in palaeoclimate for a latitudinally diverse range of active orogens? We do this using high-resolution (T159, ca. 80 × 80 km at the Equator) palaeoclimate simulations from the ECHAM5 global atmospheric general circulation model and a statistical cluster analysis of climate over different orogens (Andes, Himalayas, SE Alaska, Pacific NW USA). Time periods and boundary conditions considered include the Pliocene (PLIO, ˜ 3 Ma), the Last Glacial Maximum (LGM, ˜ 21 ka), mid-Holocene (MH, ˜ 6 ka), and pre-industrial (PI, reference year 1850). The regional simulated climates of each orogen are described by means of cluster analyses based on the variability in precipitation, 2 m air temperature, the intra-annual amplitude of these values, and monsoonal wind speeds where appropriate. Results indicate the largest differences in the PI climate existed for the LGM and PLIO climates in the form of widespread cooling and reduced precipitation in the LGM and warming and enhanced precipitation during the PLIO. The LGM climate shows the largest deviation in annual precipitation from the PI climate and shows enhanced precipitation in the temperate Andes and coastal regions for both SE Alaska and the US Pacific Northwest. Furthermore, LGM precipitation is reduced in the western Himalayas and enhanced in the eastern Himalayas, resulting in a shift of the wettest regional climates eastward along the orogen. The cluster-analysis results also suggest more climatic variability across latitudes east of the Andes in the PLIO climate than in other time slice experiments conducted here. Taken together, these results highlight significant changes in late Cenozoic regional climatology over the last ˜ 3 Myr. Comparison of simulated climate with proxy-based reconstructions for the MH and

Lichen communities and species indicate climate thresholds in southeast and south-central Alaska, USA

Science.gov (United States)

Heather T. Root; Bruce. McCune; Sarah. Jovan

2014-01-01

Because of their unique physiology, lichen communities are highly sensitive to climatic conditions,making them ideal bioindicators for climate change. Southeast and south-central Alaska host diverse and abundant lichen communities and are faced with a more rapidly changing climate than many more southerly latitudes. We develop sensitive lichen-based indicators for...

A framework for testing the ability of models to project climate change and its impacts

DEFF Research Database (Denmark)

Refsgaard, J. C.; Madsen, H.; Andréassian, V.

2014-01-01

Models used for climate change impact projections are typically not tested for simulation beyond current climate conditions. Since we have no data truly reflecting future conditions, a key challenge in this respect is to rigorously test models using proxies of future conditions. This paper presents...... a validation framework and guiding principles applicable across earth science disciplines for testing the capability of models to project future climate change and its impacts. Model test schemes comprising split-sample tests, differential split-sample tests and proxy site tests are discussed in relation...... to their application for projections by use of single models, ensemble modelling and space-time-substitution and in relation to use of different data from historical time series, paleo data and controlled experiments. We recommend that differential-split sample tests should be performed with best available proxy data...

Multi-proxy constraints on sapropel formation during the late Pliocene of central Mediterranean (southwest Sicily)

Science.gov (United States)

Plancq, Julien; Grossi, Vincent; Pittet, Bernard; Huguet, Carme; Rosell-Melé, Antoni; Mattioli, Emanuela

2015-06-01

The late Pliocene (Piacenzian) in the Mediterranean region was punctuated by short-lived episodes of widespread deposition of organic-rich sedimentary layers known as sapropels. The causes of their formation remain a long-standing debate in the science community, and require disentangling the roles of climatic/oceanographic processes that triggered higher primary productivity or enhanced organic matter preservation. The lack of data, especially of sea temperatures at sufficient temporal resolution, is one of the main challenges to solve this debate. Here, we present new organic geochemistry and micropaleontological data from the late Pliocene at Punta Grande/Punta Piccola sections (southwest Sicily) that allow untangling the mechanisms that favored the formation of two sapropel series (noted S and A) in the central Mediterranean area during this period. Sea surface (SSTs) and subsurface temperatures were estimated using three distinct organic geochemical proxies namely the alkenone unsaturation index (UK‧37), the long-chain diol index (LDI) and the tetraether index (TEX86). Reconstructed SSTs are relatively stable throughout the late Pliocene and ∼4 °C higher than modern Mediterranean SSTs, which is consistent with the climatic conditions inferred for this period from paleoclimate modeling. An increase in SST is, however, recorded by UK‧37 and LDI proxies across each sapropel horizon, supporting that the two sapropel series S and A were formed during warmer climate conditions. The comparison of SST data with variations in accumulation rates of total organic carbon and lipid-biomarkers (alkenones, long-chain alkyl diols, archaeal and bacterial tetraethers), and with changes in calcareous nannofossil assemblages, indicates that the studied sapropels might have formed under different environmental conditions. The first series of sapropels (S), deposited between 3.1 and 2.8 Ma, is likely due to a better preservation of organic matter, induced by the development

Proxies of Tropical Cyclone Isotope Spikes in Precipitation: Landfall Site Selection

Science.gov (United States)

Lawrence, J. R.; Maddocks, R.

2011-12-01

The human experience of climate change is not one of gradual changes in seasonal or yearly changes in temperature or rainfall. Despite that most paleoclimatic reconstructions attempt to provide just such information. Humans experience climate change on much shorter time scales. We remember hurricanes, weeks of drought or overwhelming rainy periods. Tropical cyclones produce very low isotope ratios in both rainfall and in atmospheric water vapor. Thus, climate proxies that potentially record these low isotope ratios offer the most concrete record of climate change to which humans can relate. The oxygen isotopic composition of tropical cyclone rainfall has the potential to be recorded in fresh water carbonate fossil material, cave deposits and corals. The hydrogen isotopic composition of tropical cyclone rainfall has the potential to be recorded in tree ring cellulose and organic matter in fresh water bodies. The Class of carbonate organisms known as Ostracoda form their carapaces very rapidly. Thus fresh water ephemeral ponds in the subtropics are ideal locations for isotopic studies because they commonly are totally dry when tropical cyclones make landfall. The other proxies suffer primarily from a dilution effect. The water from tropical cyclones is mixed with pre-existing water. In cave deposits tropical cyclone rains mix with soil and ground waters. In the near shore coral environment the rain mixes with seawater. For tree rings there are three sources of water: soil water, atmospheric water vapor that exchanges with leaf water and tropical cyclone rain. In lakes because of their large size rainfall runoff mixes with ground water and preexisting water in the lake. A region that shows considerable promise is Texas / Northeast Mexico. In a study of surface waters that developed from the passage of Tropical Storm Allison (2001) in SE Texas both the pond water and Ostracoda that bloomed recorded the low oxygen isotope signal of that storm (Lawrence et al, 2008). In

Update of indicators for climate change mitigation in Greece

International Nuclear Information System (INIS)

Dimitroulopoulou, C.; Ziomas, I.

2011-01-01

This paper analyses the factors affecting greenhouse gas (GHG) emissions in Greece, (i.e. the drivers of pressures on climate change), using environmental indicators related to energy, demographics and economic growth. The analysis is based on the data of 2008 and considers types of fuel and sectors. The Kaya identity is used to identify the relationship between drivers and pressures, using annual time series data of National GHG emissions, population, energy consumption and gross domestic product. The analysis shows that over the period 2000-2008, GHG emissions show a slight variation, but they are almost stabilised, with a total increase of 1.6%. Despite the economic growth over that period, this stabilisation may be considered as a combination of reductions in the energy intensity of GDP and the carbon intensity of energy, which are affected by improvements in energy efficiency and introduction of 'cleaner' fuels, such as natural gas and renewables in the energy mixture of the country. - Highlights: → We analyse drivers affecting GHG emissions (pressures on climate) in Greece, using indicators. → Indicators relate to energy, demographics and economic growth. → Kaya identity identifies the relationship between drivers and pressures. → GHG emissions are almost stable due to reductions in energy intensity and carbon intensity of energy. → Improvements in energy efficiency and introduction of clean fuels in energy mix reduce emissions.

Subtropical Climate Variability since the Last Glacial Maximum from Speleothem Precipitation Reconstructions in Florida

Science.gov (United States)

Polk, J.; van Beynen, P.; DeLong, K. L.; Asmerom, Y.; Polyak, V. J.

2017-12-01

Teleconnections between the tropical-subtropical regions of the Americas since the Last Glacial Maximum (LGM), particularly the Mid- to Late-Holocene, and high-resolution proxy records refining climate variability over this period continue to receive increasing attention. Here, we present a high-resolution, precisely dated speleothem record spanning multiple periods of time since the LGM ( 30 ka) for the Florida peninsula. The data indicate that the amount effect plays a significant role in determining the isotopic signal of the speleothem calcite. Collectively, the records indicate distinct differences in climate in the region between the LGM, Mid-Holocene, and Late Holocene, including a progressive shift in ocean composition and precipitation isotopic values through the period, suggesting Florida's sensitivity to regional and global climatic shifts. Comparisons between speleothem δ18O values and Gulf of Mexico marine records reveal a strong connection between the Gulf region and the terrestrial subtropical climate in the Late Holocene, while the North Atlantic's influence is clear in the earlier portions of the record. Warmer sea surface temperatures correspond to enhanced evaporation, leading to more intense atmospheric convection in Florida, and thereby modulating the isotopic composition of rainfall above the cave. These regional signals in climate extend from the subtropics to the tropics, with a clear covariance between the speleothem signal and other proxy records from around the region, as well as global agreement during the LGM period with other records. These latter connections appear to be driven by changes in the mean position of the Intertropical Convergence Zone and time series analysis of the δ18O values reveals significant multidecadal periodicities in the record, which are evidenced by agreement with the AMV and other multidecadal influences (NAO and PDO) likely having varying influence throughout the period of record. The climate variability

ePRISM: A case study in multiple proxy and mixed temporal resolution integration

Science.gov (United States)

Robinson, Marci M.; Dowsett, Harry J.

2010-01-01

As part of the Pliocene Research, Interpretation and Synoptic Mapping (PRISM) Project, we present the ePRISM experiment designed I) to provide climate modelers with a reconstruction of an early Pliocene warm period that was warmer than the PRISM interval (similar to 3.3 to 3.0 Ma), yet still similar in many ways to modern conditions and 2) to provide an example of how best to integrate multiple-proxy sea surface temperature (SST) data from time series with varying degrees of temporal resolution and age control as we begin to build the next generation of PRISM, the PRISM4 reconstruction, spanning a constricted time interval. While it is possible to tie individual SST estimates to a single light (warm) oxygen isotope event, we find that the warm peak average of SST estimates over a narrowed time interval is preferential for paleoclimate reconstruction as it allows for the inclusion of more records of multiple paleotemperature proxies.

Calibration of transfer functions between phytolith, vegetation and climate for integration of grassland dynamics in vegetation models. Application to a 50,000 yr crater lake core in Tanzania.

Science.gov (United States)

Bremond, L.; Alexandre, A.; Hely, C.; Vincens, A.; Williamson, D.; Guiot, J.

2004-12-01

Global vegetation models provide a way to translate the outputs from climate models into maps of potential vegetation distribution for present, past and future. Validation of these models goes through the comparison between model outputs and vegetation proxies for well constrained past climatic periods. Grass-dominated biomes are widespread and numerous. This diversity is hardly mirrored by common proxies such as pollen, charcoal or carbon isotopes. Phytoliths are amorphous silica that precipitate in and/or between living plant cells. They are commonly used to trace grasslands dynamics. However, calibration between phytolith assemblages, vegetation, and climate parameters are scarce. This work introduces transfer functions between phytolith indices, inter-tropical grassland physiognomy, and bio-climatic data that will be available for model/data comparisons. The Iph phytolith index discriminates tall from short grass savannas in West Africa. A transfer function allows to estimate evapo-transpiration AET/PET. The Ic phytolith index accurately estimates the proportion of Pooideae and Panicoideae grass sub-families, and potentially the C4/C3 grass dominance on East African mountains. The D/P index appears as a good proxy of Leaf Area Index (LAI) in tropical areas. These environmental parameters are commonly used as vegetation model outputs, but have been, up to now, hardly estimated by vegetation proxies. These transfer functions are applied to a 50,000 yr phytolith sequence from a crater lake (9°S; 33°E Tanzania). The record is compared to the pollen vegetation reconstruction and confronted to simulations of the LPJ-GUESS vegetation model (Stitch et. al, 2003).

Aeolian sediments deposited in Lake Hamoun; the proxy of frequency and severity of dust storms in Sistan since the late glacial

Directory of Open Access Journals (Sweden)

Mohammad Ali Hamzeh

2017-03-01

Our results suggest that the late Holocene in the Sistan Basin (facies C3 was characterized by frequent changes in MLW and SH activity. Palaeoclimatic records show since the mid Holocene to the present time, the climate of Sistan and its catchment area more or less oscillated around a steady state comparable with modern situations (Hamzeh et al. 2016. During this time, the hydroclimatic regime and Aeolian activity of the Sistan Basin and NW Himalaya have been mostly governed by MLW-associated precipitation. Periods of prolonged droughts are indicated in proxy records of NW Iran such Lake Neor (Sharifi et al. 2015, presumably consistent with high MS values in our record. It is possible that weakening of ISM, along with distal influences of the MLW during the late Holocene exposed the Lake Hamoun basin to frequent droughts. Frequent lake level fluctuations show unstable climate of the Sistan Basin during mid to late Holocene with frequent wind storms.

Linear trend and abrupt changes of climate indices in the arid region of northwestern China

Science.gov (United States)

Wang, Huaijun; Pan, Yingping; Chen, Yaning; Ye, Zhengwei

2017-11-01

In recent years, climate extreme events have caused increasing direct economic and social losses in the arid region of northwestern China. Based on daily temperature and precipitation data from 1960 to 2010, this paper discussed the linear trend and abrupt changes of climate indices. The general evolution was obtained by the empirical orthogonal function (EOF), the Mann-Kendall test, and the distribution-free cumulative sum chart (CUSUM) test. The results are as follows: (1) climate showed a warming trend at annual and seasonal scale, with all temperature indices exhibiting statistically significant changes. The warm indices have increased, with 1.37%days/decade of warm days (TX90p), 0.17 °C/decade of warmest days (TXx) and 1.97 days/decade of warm spell duration indicator (WSDI), respectively. The cold indices have decreased, with - 1.89%days/decade, 0.65 °C/decade and - 0.66 days/decade for cold nights (TN10p), coldest nights (TNn) and cold spell duration indicator (CSDI), respectively. The precipitation indices have also increased significantly, coupled with the changes of magnitude (max 1-day precipitation amount (RX1day)), frequency (rain day (R0.1)), and duration (consecutive dry days (CDD)). (2) Abrupt changes of the annual regional precipitation indices and the minimum temperature indices were observed around 1986, and that of the maximum temperature indices were observed in 1996. (3) The EOF1 indicated the overall coherent distribution for the whole study area, and its principal component (PC1) was also observed, showing a significant linear trend with an abrupt change, which were in accordance with the regional observation results. EOF2 and EOF3 show contrasts between the southern and northern study areas, and between the eastern and western study areas, respectively, whereas no significant tendency was observed for their PCs. Hence, the climate indices have changed significantly, with linear trends and abrupt changes noted for all climate indices

Nutrient regime and upwelling in the northern Benguela since the middle Holocene in a global context – a multi-proxy approach

Directory of Open Access Journals (Sweden)

S. Meisel

2011-08-01

Full Text Available The last 5500 years of climate change and environmental response in the northern Benguela Coastal Upwelling are reconstructed by means of three sediment cores from the inner shelf off central Namibia. The study is based on nutrient (δ15N, δ13C and productivity proxies (accumulation rates of total organic carbon; ARTOC. Reconstructed sea surface temperatures (alkenone-derived SST and temperatures at subsurface depths (Tδ18O; based on tests of planktonic foraminifers reflect the physical boundary conditions. The selection of proxy indicators proved a valuable basis for robust palaeo-climatic reconstructions, with the resolution ranging from multi-decadal (NAM1 over centennial (core 178 to millennial scale (core 226620. The northern Benguela experienced pronounced and rapid perturbation during the middle and late Holocene, and apparently, not all are purely local in character. In fact, numerous correlations with records from the adjacent South African subcontinent and the northern hemisphere testify to global climatic teleconnections. The Holocene Hypsithermal, for instance, is just as evident as the Little Ice Age (LIA and the Roman Warm Period. The marked SST-rise associated with the latter is substantiated by other marine and terrestrial data from the South African realm. The LIA (at least its early stages manifests itself in intensified winds and upwelling, which accords with increased rainfall receipts above the continental interior. It appears that climate signals are transferred both via the atmosphere and ocean. The combined analysis of SST and Tδ18O proved a useful tool in order to differentiate between both pathways. SSTs are primarily controlled by the intensity of atmospheric circulation features, reflecting changes of upwelling-favourable winds. Tδ18O records the temperature of the source water and often correlates with global ocean conveyor speed due to varying inputs of warm Agulhas Water. It seems as though conveyor slowdown or

Development of six PROMIS pediatrics proxy-report item banks.

Science.gov (United States)

Irwin, Debra E; Gross, Heather E; Stucky, Brian D; Thissen, David; DeWitt, Esi Morgan; Lai, Jin Shei; Amtmann, Dagmar; Khastou, Leyla; Varni, James W; DeWalt, Darren A

2012-02-22

Pediatric self-report should be considered the standard for measuring patient reported outcomes (PRO) among children. However, circumstances exist when the child is too young, cognitively impaired, or too ill to complete a PRO instrument and a proxy-report is needed. This paper describes the development process including the proxy cognitive interviews and large-field-test survey methods and sample characteristics employed to produce item parameters for the Patient Reported Outcomes Measurement Information System (PROMIS) pediatric proxy-report item banks. The PROMIS pediatric self-report items were converted into proxy-report items before undergoing cognitive interviews. These items covered six domains (physical function, emotional distress, social peer relationships, fatigue, pain interference, and asthma impact). Caregivers (n = 25) of children ages of 5 and 17 years provided qualitative feedback on proxy-report items to assess any major issues with these items. From May 2008 to March 2009, the large-scale survey enrolled children ages 8-17 years to complete the self-report version and caregivers to complete the proxy-report version of the survey (n = 1548 dyads). Caregivers of children ages 5 to 7 years completed the proxy report survey (n = 432). In addition, caregivers completed other proxy instruments, PedsQL™ 4.0 Generic Core Scales Parent Proxy-Report version, PedsQL™ Asthma Module Parent Proxy-Report version, and KIDSCREEN Parent-Proxy-52. Item content was well understood by proxies and did not require item revisions but some proxies clearly noted that determining an answer on behalf of their child was difficult for some items. Dyads and caregivers of children ages 5-17 years old were enrolled in the large-scale testing. The majority were female (85%), married (70%), Caucasian (64%) and had at least a high school education (94%). Approximately 50% had children with a chronic health condition, primarily asthma, which was diagnosed or treated within 6

Sea ice and primary production proxies in surface sediments from a High Arctic Greenland fjord

DEFF Research Database (Denmark)

Ribeiro, Sofia; Sejr, Mikael K; Limoges, Audrey

2017-01-01

Monitoring Programme. Clear spatial gradients in organic carbon and biogenic silica contents reflected marine influence, nutrient availability and river-induced turbidity, in good agreement with in situ measurements. The sea ice proxy IP25 was detected at all sites but at low concentrations, indicating...... that IP25 records from fjords need to be carefully considered and not directly compared to marine settings. The sea ice-associated biomarker HBI III revealed an open-water signature, with highest concentrations near the mid-July ice edge. This proxy evaluation is an important step towards reliable......In order to establish a baseline for proxy-based reconstructions for the Young Sound–Tyrolerfjord system (Northeast Greenland), we analysed the spatial distribution of primary production and sea ice proxies in surface sediments from the fjord, against monitoring data from the Greenland Ecosystem...

Spring Indices (SI): National (and Global) Indicators of Climate Impacts on Ecosystems and Society

Science.gov (United States)

Betancourt, J. L.; Schwartz, M. D.; Ault, T. R.; McCabe, G. J.; Macalady, A. K.; Pederson, G. T.; Cook, B. P.; Henebry, G. M.; Moore, D. J.; Enquist, C.

2011-12-01

Indicators are vital in everyday life, such as tracking blood pressure to assess your health or monitoring the nation's economy using unemployment rates. Tracking the state of the environment in a uniform and integrated manner requires simple and broadly-applicable indicators of year-to-year variability and change. For example, indices such as the Start of Season (SOS) in remotely-sensed land surface phenology, Center of Mass (CM) in the hydrology of snowfed inland waters, and other biogeophysical metrics are being widely used as metrics of global change in seasonal timing. Here, we present a new, standardized spring index (SSI) that uses only daily minimum and maximum temperatures as input. This builds on an earlier version of the spring indices (SI) for lilac and honeysuckle phenology (first leaf and first flower) that required plant chilling to be satisfied over winter. The SSI tracks the transition from winter to spring by tallying phenologically relevant variables, (such as the number and intensity of warm days and total hours of sunlight) from January 1st onward, while ignoring the chilling requirement. This adjustment allows determination of first leaf and first bloom dates across the entire USA, including southernmost latitudes. Outputs from the new SSI is highly correlated with the earlier version, and both models process weather data into indices directly related to growth and development of many plants. Spatially averaged anomalies of SSI are well correlated with remotely sensed data and phenological observations from a wide variety of trees and shrubs in Europe, China, and North America. An advantage of SSI is that it only "sees" the atmosphere, meaning that it is free of local biological effects. Therefore, it can enhance the ability to identify important relationships between the large-scale climate modes of variability and the index itself, an advantage over other plant-based indices (such as SOS). If the state of these atmospheric modes can be

Effect of climate change on environmental flow indicators in the narew basin, poland.

Science.gov (United States)

Piniewski, Mikołaj; Laizé, Cédric L R; Acreman, Michael C; Okruszko, Tomasz; Schneider, Christof

2014-01-01

Environmental flows-the quantity of water required to maintain a river ecosystem in its desired state-are of particular importance in areas of high natural value. Water-dependent ecosystems are exposed to the risk of climate change through altered precipitation and evaporation. Rivers in the Narew basin in northeastern Poland are known for their valuable river and wetland ecosystems, many of them in pristine or near-pristine condition. The objective of this study was to assess changes in the environmental flow regime of the Narew river system, caused by climate change, as simulated by hydrological models with different degrees of physical characterization and spatial aggregation. Two models were assessed: the river basin scale model Soil and Water Assessment Tool (SWAT) and the continental model of water availability and use WaterGAP. Future climate change scenarios were provided by two general circulation models coupled with the A2 emission scenario: IPSL-CM4 and MIROC3.2. To assess the impact of climate change on environmental flows, a method based conceptually on the "range of variability" approach was used. The results indicate that the environmental flow regime in the Narew basin is subject to climate change risk, whose magnitude and spatial variability varies with climate model and hydrological modeling scale. Most of the analyzed sites experienced moderate impacts for the Generic Environmental Flow Indicator (GEFI), the Floodplain Inundation Indicator, and the River Habitat Availability Indicator. The consistency between SWAT and WaterGAP for GEFI was medium: in 55 to 66% of analyzed sites, the models suggested the same level of impact. Hence, we suggest that state-of-the-art, high-resolution, global- or continental-scale models, such as WaterGAP, could be useful tools for water management decision-makers and wetland conservation practitioners, whereas models such as SWAT should serve as a complementary tool for more specific, smaller-scale, local

Trends in Middle East climate extreme indices from 1950 to 2003

Science.gov (United States)

Zhang, Xuebin; Aguilar, Enric; Sensoy, Serhat; Melkonyan, Hamlet; Tagiyeva, Umayra; Ahmed, Nader; Kutaladze, Nato; Rahimzadeh, Fatemeh; Taghipour, Afsaneh; Hantosh, T. H.; Albert, Pinhas; Semawi, Mohammed; Karam Ali, Mohammad; Said Al-Shabibi, Mansoor Halal; Al-Oulan, Zaid; Zatari, Taha; Al Dean Khelet, Imad; Hamoud, Saleh; Sagir, Ramazan; Demircan, Mesut; Eken, Mehmet; Adiguzel, Mustafa; Alexander, Lisa; Peterson, Thomas C.; Wallis, Trevor

2005-11-01

A climate change workshop for the Middle East brought together scientists and data for the region to produce the first area-wide analysis of climate extremes for the region. This paper reports trends in extreme precipitation and temperature indices that were computed during the workshop and additional indices data that became available after the workshop. Trends in these indices were examined for 1950-2003 at 52 stations covering 15 countries, including Armenia, Azerbaijan, Bahrain, Cyprus, Georgia, Iran, Iraq, Israel, Jordan, Kuwait, Oman, Qatar, Saudi Arabia, Syria, and Turkey. Results indicate that there have been statistically significant, spatially coherent trends in temperature indices that are related to temperature increases in the region. Significant, increasing trends have been found in the annual maximum of daily maximum and minimum temperature, the annual minimum of daily maximum and minimum temperature, the number of summer nights, and the number of days where daily temperature has exceeded its 90th percentile. Significant negative trends have been found in the number of days when daily temperature is below its 10th percentile and daily temperature range. Trends in precipitation indices, including the number of days with precipitation, the average precipitation intensity, and maximum daily precipitation events, are weak in general and do not show spatial coherence. The workshop attendees have generously made the indices data available for the international research community.

Mountains as early warning indicators of climate change

Science.gov (United States)

Williams, M. W.

2015-12-01

The panoramic splendor and complexity of mountain environments have inspired and challenged humans for centuries. These areas have been variously perceived as physical structures to be conquered, as sites of spiritual inspiration, and as some of the last untamed natural places on Earth. In our time, the perception that "mountains are forever" may provide solace to those seeking stability in a rapidly changing world. However, changes in the hydrology and in the abundance and species composition of the native flora and fauna of mountain ecosystems are potential bellwethers of global change, because these systems have a propensity to amplify environmental changes within specific portions of this landscape. Mountain areas are thus sentinels of climate change. We are seeing effects today in case histories I present from the Himalaya's, Andes, Alps, and Rocky Mountains. Furthermore, these ecosystem changes are occurring in mountain areas before they occur in downstream ecosystems. Thus, mountains are early warning indicators of perturbations such as climate change. The sensitivity of mountain ecosystems begs for enhanced protection and worldwide protection. Our understanding of the processes that control mountain ecosystems—climate interactions, snowmelt runoff, biotic diversity, nutrient cycling—is much less developed compared to downstream ecosystems where human habitation and development has resulted in large investments in scientific knowledge to sustain health and agriculture. To address these deficiencies, I propose the formation of an international mountain research consortium.

The role of proxy information in missing data analysis.

Science.gov (United States)

Huang, Rong; Liang, Yuanyuan; Carrière, K C

2005-10-01

This article investigates the role of proxy data in dealing with the common problem of missing data in clinical trials using repeated measures designs. In an effort to avoid the missing data situation, some proxy information can be gathered. The question is how to treat proxy information, that is, is it always better to utilize proxy information when there are missing data? A model for repeated measures data with missing values is considered and a strategy for utilizing proxy information is developed. Then, simulations are used to compare the power of a test using proxy to simply utilizing all available data. It is concluded that using proxy information can be a useful alternative when such information is available. The implications for various clinical designs are also considered and a data collection strategy for efficiently estimating parameters is suggested.

Transparent Proxy for Secure E-Mail

Science.gov (United States)

Michalák, Juraj; Hudec, Ladislav

2010-05-01

The paper deals with the security of e-mail messages and e-mail server implementation by means of a transparent SMTP proxy. The security features include encryption and signing of transported messages. The goal is to design and implement a software proxy for secure e-mail including its monitoring, administration, encryption and signing keys administration. In particular, we focus on automatic public key on-the-fly encryption and signing of e-mail messages according to S/MIME standard by means of an embedded computer system whose function can be briefly described as a brouter with transparent SMTP proxy.

Proxy Graph: Visual Quality Metrics of Big Graph Sampling.

Science.gov (United States)

Nguyen, Quan Hoang; Hong, Seok-Hee; Eades, Peter; Meidiana, Amyra

2017-06-01

Data sampling has been extensively studied for large scale graph mining. Many analyses and tasks become more efficient when performed on graph samples of much smaller size. The use of proxy objects is common in software engineering for analysis and interaction with heavy objects or systems. In this paper, we coin the term 'proxy graph' and empirically investigate how well a proxy graph visualization can represent a big graph. Our investigation focuses on proxy graphs obtained by sampling; this is one of the most common proxy approaches. Despite the plethora of data sampling studies, this is the first evaluation of sampling in the context of graph visualization. For an objective evaluation, we propose a new family of quality metrics for visual quality of proxy graphs. Our experiments cover popular sampling techniques. Our experimental results lead to guidelines for using sampling-based proxy graphs in visualization.

Development of six PROMIS pediatrics proxy-report item banks

Directory of Open Access Journals (Sweden)

Irwin Debra E

2012-02-01

Full Text Available Abstract Background Pediatric self-report should be considered the standard for measuring patient reported outcomes (PRO among children. However, circumstances exist when the child is too young, cognitively impaired, or too ill to complete a PRO instrument and a proxy-report is needed. This paper describes the development process including the proxy cognitive interviews and large-field-test survey methods and sample characteristics employed to produce item parameters for the Patient Reported Outcomes Measurement Information System (PROMIS pediatric proxy-report item banks. Methods The PROMIS pediatric self-report items were converted into proxy-report items before undergoing cognitive interviews. These items covered six domains (physical function, emotional distress, social peer relationships, fatigue, pain interference, and asthma impact. Caregivers (n = 25 of children ages of 5 and 17 years provided qualitative feedback on proxy-report items to assess any major issues with these items. From May 2008 to March 2009, the large-scale survey enrolled children ages 8-17 years to complete the self-report version and caregivers to complete the proxy-report version of the survey (n = 1548 dyads. Caregivers of children ages 5 to 7 years completed the proxy report survey (n = 432. In addition, caregivers completed other proxy instruments, PedsQL™ 4.0 Generic Core Scales Parent Proxy-Report version, PedsQL™ Asthma Module Parent Proxy-Report version, and KIDSCREEN Parent-Proxy-52. Results Item content was well understood by proxies and did not require item revisions but some proxies clearly noted that determining an answer on behalf of their child was difficult for some items. Dyads and caregivers of children ages 5-17 years old were enrolled in the large-scale testing. The majority were female (85%, married (70%, Caucasian (64% and had at least a high school education (94%. Approximately 50% had children with a chronic health condition, primarily

Advances in Alkenone Paleotemperature Proxies: Analytical Methods, Novel Structures and Haptophyte Species, Biosynthesis, New indices and Ecological Aspects

Science.gov (United States)

Huang, Y.; Longo, W. M.; Zheng, Y.; Richter, N.; Dillon, J. T.; Theroux, S.; D'Andrea, W. J.; Toney, J. L.; Wang, L.; Amaral-Zettler, L. A.

2017-12-01

Alkenones are mature, well-established paleo-sea surface temperature proxies that have been widely applied for more than three decades. However, recent advances across a broad range of alkenone-related topics at Brown University are inviting new paleoclimate and paleo-environmental applications for these classic biomarkers. In this presentation, I will summarize our progress in the following areas: (1) Discovery of a freshwater alkenone-producing haptophyte species and structural elucidation of novel alkenone structures unique to the species, performing in-situ temperature calibrations, and classifying alkenone-producing haptophytes into three groups based on molecular ecological approaches (with the new species belonging to Group I Isochrysidales); (2) A global survey of Group I haptophyte distributions and environmental conditions favoring the presence of this alga, as well as examples of using Group I alkenones for paleotemperature reconstructions; (3) New gas chromatographic columns that allow unprecedented resolution of alkenones and alkenoates and associated structural isomers, and development of a new suite of paleotemperature and paleoenvironmental proxies; (4) A new liquid chromatographic separation technique that allows efficient cleanup of alkenones and alkenoates (without the need for saponification) for subsequent coelution-free gas chromatographic analysis; (5) Novel structural features revealed by new analytical methods that now allow a comprehensive re-assessment of taxonomic features of various haptophyte species, with principal component analysis capable of fully resolving species biomarker distributions; (6) Development of UK37 double prime (UK37'') for Group II haptophytes (e.g., those occurring in saline lakes and estuaries), that differs from the traditional unsaturation indices used for SST reconstructions; (7) New assessment of how mixed inputs from different alkenone groups may affect SST reconstructions in marginal ocean environments and

Using large-scale climate indices in climate change ecology studies

DEFF Research Database (Denmark)

Forchhammer, Mads Cedergreen; Post, Eric

2004-01-01

Ecological responses, El Niño 3.4, Long-term climate variability, North Atlantic Oscillation, North Pacific Oscillation, Teleconnection patterns......Ecological responses, El Niño 3.4, Long-term climate variability, North Atlantic Oscillation, North Pacific Oscillation, Teleconnection patterns...

Predicting Extreme Droughts in Savannah Africa: A Comparison of Proxy and Direct Measures in Detecting Biomass Fluctuations, Trends and Their Causes.

Science.gov (United States)

Western, David; Mose, Victor N; Worden, Jeffrey; Maitumo, David

2015-01-01

We monitored pasture biomass on 20 permanent plots over 35 years to gauge the reliability of rainfall and NDVI as proxy measures of forage shortfalls in a savannah ecosystem. Both proxies are reliable indicators of pasture biomass at the onset of dry periods but fail to predict shortfalls in prolonged dry spells. In contrast, grazing pressure predicts pasture deficits with a high degree of accuracy. Large herbivores play a primary role in determining the severity of pasture deficits and variation across habitats. Grazing pressure also explains oscillations in plant biomass unrelated to rainfall. Plant biomass has declined steadily and biomass per unit of rainfall has fallen by a third, corresponding to a doubling in grazing intensity over the study period. The rising probability of forage deficits fits local pastoral perceptions of an increasing frequency of extreme shortfalls. The decline in forage is linked to sedentarization, range loss and herbivore compression into drought refuges, rather than climate change. The results show that the decline in rangeland productivity and increasing frequency of pasture shortfalls can be ameliorated by better husbandry practices and reinforces the need for ground monitoring to complement remote sensing in forecasting pasture shortfalls.

Secure Mobile Agent from Leakage-Resilient Proxy Signatures

Directory of Open Access Journals (Sweden)

Fei Tang

2015-01-01

Full Text Available A mobile agent can sign a message in a remote server on behalf of a customer without exposing its secret key; it can be used not only to search for special products or services, but also to make a contract with a remote server. Hence a mobile agent system can be used for electronic commerce as an important key technology. In order to realize such a system, Lee et al. showed that a secure mobile agent can be constructed using proxy signatures. Intuitively, a proxy signature permits an entity (delegator to delegate its signing right to another entity (proxy to sign some specified messages on behalf of the delegator. However, the proxy signatures are often used in scenarios where the signing is done in an insecure environment, for example, the remote server of a mobile agent system. In such setting, an adversary could launch side-channel attacks to exploit some leakage information about the proxy key or even other secret states. The proxy signatures which are secure in the traditional security models obviously cannot provide such security. Based on this consideration, in this paper, we design a leakage-resilient proxy signature scheme for the secure mobile agent systems.

Climate Change Indicators: Health and Society

Science.gov (United States)

... chapter looks at some of the ways that climate change is affecting human health and society, including changes in Lyme disease, West ... health effects. Why does it matter? Changes in climate affect the ... to human health and welfare. Warmer average temperatures will likely lead ...

Time-and-ID-Based Proxy Reencryption Scheme

Directory of Open Access Journals (Sweden)

Kambombo Mtonga

2014-01-01

Full Text Available Time- and ID-based proxy reencryption scheme is proposed in this paper in which a type-based proxy reencryption enables the delegator to implement fine-grained policies with one key pair without any additional trust on the proxy. However, in some applications, the time within which the data was sampled or collected is very critical. In such applications, for example, healthcare and criminal investigations, the delegatee may be interested in only some of the messages with some types sampled within some time bound instead of the entire subset. Hence, in order to carter for such situations, in this paper, we propose a time-and-identity-based proxy reencryption scheme that takes into account the time within which the data was collected as a factor to consider when categorizing data in addition to its type. Our scheme is based on Boneh and Boyen identity-based scheme (BB-IBE and Matsuo’s proxy reencryption scheme for identity-based encryption (IBE to IBE. We prove that our scheme is semantically secure in the standard model.

Climate variability in the subarctic area for the last 2 millennia

Science.gov (United States)

Nicolle, Marie; Debret, Maxime; Massei, Nicolas; Colin, Christophe; deVernal, Anne; Divine, Dmitry; Werner, Johannes P.; Hormes, Anne; Korhola, Atte; Linderholm, Hans W.

2018-01-01

To put recent climate change in perspective, it is necessary to extend the instrumental climate records with proxy data from paleoclimate archives. Arctic climate variability for the last 2 millennia has been investigated using statistical and signal analyses from three regionally averaged records from the North Atlantic, Siberia and Alaska based on many types of proxy data archived in the Arctic 2k database v1.1.1. In the North Atlantic and Alaska, the major climatic trend is characterized by long-term cooling interrupted by recent warming that started at the beginning of the 19th century. This cooling is visible in the Siberian region at two sites, warming at the others. The cooling of the Little Ice Age (LIA) was identified from the individual series, but it is characterized by wide-range spatial and temporal expression of climate variability, in contrary to the Medieval Climate Anomaly. The LIA started at the earliest by around AD 1200 and ended at the latest in the middle of the 20th century. The widespread temporal coverage of the LIA did not show regional consistency or particular spatial distribution and did not show a relationship with archive or proxy type either. A focus on the last 2 centuries shows a recent warming characterized by a well-marked warming trend parallel with increasing greenhouse gas emissions. It also shows a multidecadal variability likely due to natural processes acting on the internal climate system on a regional scale. A ˜ 16-30-year cycle is found in Alaska and seems to be linked to the Pacific Decadal Oscillation, whereas ˜ 20-30- and ˜ 50-90-year periodicities characterize the North Atlantic climate variability, likely in relation with the Atlantic Multidecadal Oscillation. These regional features are probably linked to the sea ice cover fluctuations through ice-temperature positive feedback.

Validity of proxy data obtained by different psychological autopsy information reconstruction techniques.

Science.gov (United States)

Fang, L; Zhang, J

2010-01-01

Two informants were interviewed for each of 416 living controls (individuals sampled from the normal population) interviewed in a Chinese case-control psychological autopsy study. The validity of proxy data, obtained using seven psychological autopsy information reconstruction techniques (types 1, 2 and A - E), was evaluated, with living controls' self reports used as the gold-standard. Proxy data for reconstruction technique types 1, 2 and D on the Impulsivity Inventory Scale (total impulsivity score) were no different from the living controls' self report gold standard, whereas data for types A and E were smaller than data from living controls. On the 'acceptance or resignation' sub-scale of the avoidance coping dimension of the Moos Coping Response Inventory, information obtained by reconstruction technique types 1 and D was not significantly different from the living controls' self reports, whereas proxy data from types 2, A and E were smaller than those from the living controls. No statistically significant differences were identified for other proxy data obtained by reconstruction technique types 1, 2, A, D and E. These results indicate that using a second informant does not significantly enhance information reconstruction for the target.

Proxy-based reconstruction of erythemal UV doses over Estonia for 1955–2004

Directory of Open Access Journals (Sweden)

K. Eerme

2006-08-01

Full Text Available A proxy-based reconstruction of the erythemally-weighted UV doses for 1955-2004 has been performed for the Tartu-Tõravere Meteorological Station (58°16' N, 26°28' E, 70 m a.s.l. site. The pyrheliometer-measured daily sum of direct irradiance on partly cloudy and clear days, and the pyranometer-measured daily sum of global irradiance on overcast days were used as the cloudiness influence related proxies. The TOMS ozone data have been used for detecting the daily deviations from the climatic value (averaged annual cycle. In 1998–2004, the biases between the measured and reconstructed daily doses in 55.5% of the cases were within ±10% and in 83.5% of the cases within ±20%, on average. In the summer half-year these amounts were 62% and 88%, respectively. In most years the results for longer intervals did not differ significantly, if no correction was made for the daily deviations of total ozone from its climatic value. The annual and summer half-yearly erythemal doses (contributing, on average, 89% of the annual value agreed within ±2%, except for the years after major volcanic eruptions and one extremely fine weather year (2002. Using the daily relative sunshine duration as a proxy without detailed correction for atmospheric turbidity results in biases of 2–4% in the summer half-yearly dose in the years after major volcanic eruptions and a few other years of high atmospheric turbidity. The year-to-year variations of the summer half-yearly erythemal dose in 1955–2004 were found to be within 92–111% relative to their average value. Exclusion of eight extreme years reduces this range for the remaining to 95–105.5%. Due to the quasi-periodic alternation of wet and dry periods, the interval of cloudy summers 1976–1993 regularly manifests summer half-yearly erythemal dose values lower than the 1955–2004 average. Since 1996/1997 midwinters have been darker than on average.

Proxy-based reconstruction of erythemal UV doses over Estonia for 1955–2004

Directory of Open Access Journals (Sweden)

K. Eerme

2006-08-01

Full Text Available A proxy-based reconstruction of the erythemally-weighted UV doses for 1955-2004 has been performed for the Tartu-Tõravere Meteorological Station (58°16' N, 26°28' E, 70 m a.s.l. site. The pyrheliometer-measured daily sum of direct irradiance on partly cloudy and clear days, and the pyranometer-measured daily sum of global irradiance on overcast days were used as the cloudiness influence related proxies. The TOMS ozone data have been used for detecting the daily deviations from the climatic value (averaged annual cycle. In 1998–2004, the biases between the measured and reconstructed daily doses in 55.5% of the cases were within ±10% and in 83.5% of the cases within ±20%, on average. In the summer half-year these amounts were 62% and 88%, respectively. In most years the results for longer intervals did not differ significantly, if no correction was made for the daily deviations of total ozone from its climatic value. The annual and summer half-yearly erythemal doses (contributing, on average, 89% of the annual value agreed within ±2%, except for the years after major volcanic eruptions and one extremely fine weather year (2002. Using the daily relative sunshine duration as a proxy without detailed correction for atmospheric turbidity results in biases of 2–4% in the summer half-yearly dose in the years after major volcanic eruptions and a few other years of high atmospheric turbidity. The year-to-year variations of the summer half-yearly erythemal dose in 1955–2004 were found to be within 92–111% relative to their average value. Exclusion of eight extreme years reduces this range for the remaining to 95–105.5%. Due to the quasi-periodic alternation of wet and dry periods, the interval of cloudy summers 1976–1993 regularly manifests summer half-yearly erythemal dose values lower than the 1955–2004 average. Since 1996/1997 midwinters have been darker than on average.

Graphite-(Mo,W)S2 intergrowth as a palaeoenvironmental proxy in metasedimentary rocks

Science.gov (United States)

Cabral, Alexandre Raphael; Zeh, Armin; da Silva Viana, Nívea Cristina; Schirmer, Thomas; Lehmann, Bernd

2017-12-01

Molybdenum enrichment in pristine organic-C-rich sedimentary rocks forms the basis for inferring the presence of dissolved oxygen in seawater. Organic matter removes dissolved hexavalent Mo from seawater where anoxic and euxinic conditions are attained. However, it is unknown whether this Mo-based proxy is retained under metamorphic conditions where organic C is no longer preserved. Here, we describe aggregates of graphite and molybdenite (MoS2) containing up to 21 mass per cent of W as tungstenite (WS2) in solid solution. These aggregates are disseminated in a sulfide-rich Mn-silicate-carbonate rock (queluzite), metamorphosed under amphibolite-facies conditions within the Archaean Barbacena greenstone belt in Minas Gerais, Brazil. Our finding indicates that: (i) W is, like Mo, a palaeoenvironmental proxy; (ii) the W proxy is sensitive to high fS2/fO2 environments; (iii) both Mo and W proxies survive amphibolite-facies overprint as (Mo,W)S2 intergrown with graphite. Archaean greenstones are potential candidates for storing palaeoenvironmental information as (Mo,W)S2-graphite intergrowths.

Climate change between the mid and late Holocene in northern high latitudes – Part 2: Model-data comparisons

Directory of Open Access Journals (Sweden)

K. Holmgren

2010-09-01

Full Text Available The climate response over northern high latitudes to the mid-Holocene orbital forcing has been investigated in three types of PMIP (Paleoclimate Modelling Intercomparison Project simulations with different complexity of the modelled climate system. By first undertaking model-data comparison, an objective selection method has been applied to evaluate the capability of the climate models to reproduce the spatial response pattern seen in proxy data. The possible feedback mechanisms behind the climate response have been explored based on the selected model simulations. Subsequent model-model comparisons indicate the importance of including the different physical feedbacks in the climate models. The comparisons between the proxy-based reconstructions and the best fit selected simulations show that over the northern high latitudes, summer temperature change follows closely the insolation change and shows a common feature with strong warming over land and relatively weak warming over ocean at 6 ka compared to 0 ka. Furthermore, the sea-ice-albedo positive feedback enhances this response. The reconstructions of temperature show a stronger response to enhanced insolation in the annual mean temperature than winter and summer temperature. This is verified in the model simulations and the behaviour is attributed to the larger contribution from the large response in autumn. Despite a smaller insolation during winter at 6 ka, a pronounced warming centre is found over Barents Sea in winter in the simulations, which is also supported by the nearby northern Eurasian continental and Fennoscandian reconstructions. This indicates that in the Arctic region, the response of the ocean and the sea ice to the enhanced summer insolation is more important for the winter temperature than the synchronous decrease of the insolation.

Time-and-ID-Based Proxy Reencryption Scheme

OpenAIRE

Mtonga, Kambombo; Paul, Anand; Rho, Seungmin

2014-01-01

Time- and ID-based proxy reencryption scheme is proposed in this paper in which a type-based proxy reencryption enables the delegator to implement fine-grained policies with one key pair without any additional trust on the proxy. However, in some applications, the time within which the data was sampled or collected is very critical. In such applications, for example, healthcare and criminal investigations, the delegatee may be interested in only some of the messages with some types sampled wi...

Web Proxy Auto Discovery for the WLCG

Science.gov (United States)

Dykstra, D.; Blomer, J.; Blumenfeld, B.; De Salvo, A.; Dewhurst, A.; Verguilov, V.

2017-10-01

All four of the LHC experiments depend on web proxies (that is, squids) at each grid site to support software distribution by the CernVM FileSystem (CVMFS). CMS and ATLAS also use web proxies for conditions data distributed through the Frontier Distributed Database caching system. ATLAS & CMS each have their own methods for their grid jobs to find out which web proxies to use for Frontier at each site, and CVMFS has a third method. Those diverse methods limit usability and flexibility, particularly for opportunistic use cases, where an experiment’s jobs are run at sites that do not primarily support that experiment. This paper describes a new Worldwide LHC Computing Grid (WLCG) system for discovering the addresses of web proxies. The system is based on an internet standard called Web Proxy Auto Discovery (WPAD). WPAD is in turn based on another standard called Proxy Auto Configuration (PAC). Both the Frontier and CVMFS clients support this standard. The input into the WLCG system comes from squids registered in the ATLAS Grid Information System (AGIS) and CMS SITECONF files, cross-checked with squids registered by sites in the Grid Configuration Database (GOCDB) and the OSG Information Management (OIM) system, and combined with some exceptions manually configured by people from ATLAS and CMS who operate WLCG Squid monitoring. WPAD servers at CERN respond to http requests from grid nodes all over the world with a PAC file that lists available web proxies, based on IP addresses matched from a database that contains the IP address ranges registered to organizations. Large grid sites are encouraged to supply their own WPAD web servers for more flexibility, to avoid being affected by short term long distance network outages, and to offload the WLCG WPAD servers at CERN. The CERN WPAD servers additionally support requests from jobs running at non-grid sites (particularly for LHC@Home) which they direct to the nearest publicly accessible web proxy servers. The responses

Establishment of an indicator concept for the German strategy on adaptation to climate change

Energy Technology Data Exchange (ETDEWEB)

Schoenthaler, Konstanze; Andrian-Werburg, Stefan von; Wulfert, Katrin [Bosch und Partner GmbH, Muenchen (Germany); Luthardt, Vera; Kreinsen, Beatrice; Schultz-Sternberg, R.; Hommel, Robert [Hochschule fuer Nachhaltige Entwicklung Eberswalde (Germany)

2010-11-15

Even if we succeed in achieving the EU target of reducing global warming to 2 C, it will be absolutely essential to adapt to changing climatic conditions. The greenhouse gases currently present in the atmosphere will influence the climate in coming decades. The day on which it is quite clear which climatic scenario prevails, so that it is possible to model all relevant processes down to regional level, will be the day on which it is too late to adapt to the actual scenario. Our endeavours to adapt to climate change do not mean, however, that we can neglect to take measures in order to reduce the output of greenhouse gases. It is important to remember that on their own, neither adaptation nor mitigation can prevent the grave impacts resulting from climate change. In fact, they complement each other meaningfully thus helping to alleviate the risks of climate change. On 17th December 2008 the German Federal Cabinet adopted the DAS (German Strategy for the Adaptation to Climate Change), (Bundesregierung 2008). The DAS has created the framework for adapting to the consequences of climate change in Germany. First and fore-most, the DAS contributes its guidelines at Federal level, to provide a guideline for agents at other levels. The Strategy lays the foundation for a medium-term process. In conjunction with the individual Federal States and other groups representing various sectors of society, the Strategy provides a step-by-step assessment of the risks of climate change. Furthermore, it states the potential requirements for action, and defines the appropriate goals and potential adaptation measures to be developed and implemented in this process. In due course, the Federal Environment Agency (UBA) will design a comprehensive set of tools to support and advance the DAS. An integral part of this will be the Special Information System 'Adaptation' (FISKA) and an Indicator System to aid adaptation. The latter is one of the key tasks identified for the DAS. As far

High-latitude tree-ring data: Records of climatic change and ecological response

International Nuclear Information System (INIS)

Graumlich, L.J.

1991-01-01

Tree-ring data provide critical information regarding two fundamental questions as to the role of the polar regions in global change: (1) what is the nature of climatic variability? and (2) what is the response of vegetation to climatic variability? Tree-ring-based climatic reconstructions document the variability of the climate system on time scales of years to centuries. Dendroclimatic reconstructions indicate that the climatic episodes defined on the basis of documentary evidence in western Europe (i.e., Medieval Warm Episode, ca. A.D. 1000-1300; Little Ice Age, ca. A.D. 1550-1850) can be observed at some high-latitude sites (ex., Polar Urals). Spatial variation in long-term temperature trends (ex., northern Fennoscandia vs. Polar Urals) demonstrates the importance of regional-scale climatic controls. When collated into global networks, proxy-based climatic reconstructions can be used to test hypotheses as to the relative importance of external forcing vs. internal variation in governing climatic variation. Specifically, such a global network would allow the quantification of the climatic response to various permutations of factors thought to be important in governing decadal- to centennial-scale climatic variation. Tree populations respond to annual- to centennial-scale climatic variation through changes in rates of growth, establishment, and mortality. Tree-ring studies that document multiple aspects of high-latitude treeline dynamics (i.e., the timing of tree establishment, mortality, and changes from krummholz to upright growth) indicate a complex interaction between growth form, population processes, and environmental variability. Such interactions result in varying sensitivities of high-latitude trees to climatic change

Soils and climate: redness and weathering as indicators of mean annual precipitation

Science.gov (United States)

Lucke, Bernhard

2016-04-01

Paleosols can be used as archives of past changes of climate and landscapes, but their interpretation has to be based on modern analogies such as Budyko's law of soil zonality. These can be very useful if the respective processes of soil formation are sufficiently well understood. However, some soils such as the Terra Rossa or Red Mediterranean Soils, that are widespread at the fringes of the steppes and deserts, are still disputed with regard to their genesis and environmental significance. In particular, there is no agreement whether they resemble current environmental conditions, or are inherited from climates or sediments of the past. In this context, a remarkable change of the color of surface soils can be observed when driving from the city of Irbid in Jordan towards the east. Soil color apparently changes slowly, but steadily from dark red to yellow colors. However, attempting to express these color changes in numerical form is challenging, and it seemed questionable whether color is indeed connected with soil weathering intensity, or an optical illusion. However, a systematic comparison of different approaches of calculating soil redness found that the CIELAB-color system is suited for numerical expressions of soil redness and performs better than the Munsell charts. Along the investigated transect in Jordan, soil color seems strongly connected with weathering intensity, since various weathering indicators point to a steady increase of soil development with moisture. This suggests that such indices can well be used in semi-arid areas of 250-600 mm of mean annual precipitation. A very strong correlation of magnetic enhancement and rainfall indicates that the investigated soils are forming in equilibrium with current climatic conditions, and regressions based on this gradient might be suited for estimating paleorainfalls recorded by buried paelosols. It seems therefore that surface Terra Rossa soils in Jordan can be in equilibrium with current climate

Long Series of GNSS Integrated Precipitable Water as a Climate Change Indicator

Directory of Open Access Journals (Sweden)

Kruczyk Michał

2015-12-01

Full Text Available This paper investigates information potential contained in tropospheric delay product for selected International GNSS Service (IGS stations in climatologic research. Long time series of daily averaged Integrated Precipitable Water (IPW can serve as climate indicator. The seasonal model of IPW change has been adjusted to the multi-year series (by the least square method. Author applied two modes: sinusoidal and composite (two or more oscillations. Even simple sinusoidal seasonal model (of daily IPW values series clearly represents diversity of world climates. Residuals in periods from 10 up to 17 years are searched for some long-term IPW trend – self-evident climate change indicator. Results are ambiguous: for some stations or periods IPW trends are quite clear, the following years (or the other station not visible. Method of fitting linear trend to IPW series does not influence considerably the value of linear trend. The results are mostly influenced by series length, completeness and data (e.g. meteorological quality. The longer and more homogenous IPW series, the better chance to estimate the magnitude of climatologic IPW changes.

A multi-hazard regional level impact assessment for Europe combining indicators of climatic and non-climatic change

NARCIS (Netherlands)

Lung, T.; Lavalle, C.; Hiederer, R.; Dosio, A.; Bouwer, L.M.

2013-01-01

To better prioritise adaptation strategies to a changing climate that are currently being developed, there is a need for quantitative regional level assessments that are systematic and comparable across multiple weather hazards. This study presents an indicator-based impact assessment framework at

Solar forced Dansgaard-Oeschger events and their phase relation with solar proxies

DEFF Research Database (Denmark)

Ditlevsen, Peter; Braun, H.; Chialvo, D. R.

2008-01-01

of a highly nonlinear system to quasi-periodic solar forcing plus noise. This hypothesis was challenged as inconsistent with the observed variability in the phase relation between proxies of solar activity and Greenland climate. Here we reject the claim of inconsistency by showing that this phase variability...... is a robust, generic feature of the nonlinear dynamics of DO events, as described by a model. This variability is expected from the fact that the events are threshold crossing events, resulting from a cooperative process between the periodic forcing and the noise. This process produces a fluctuating phase...

Regional climate change trends and uncertainty analysis using extreme indices: A case study of Hamilton, Canada

OpenAIRE

Razavi, Tara; Switzman, Harris; Arain, Altaf; Coulibaly, Paulin

2016-01-01

This study aims to provide a deeper understanding of the level of uncertainty associated with the development of extreme weather frequency and intensity indices at the local scale. Several different global climate models, downscaling methods, and emission scenarios were used to develop extreme temperature and precipitation indices at the local scale in the Hamilton region, Ontario, Canada. Uncertainty associated with historical and future trends in extreme indices and future climate projectio...

Geomorphic features as indicators of climatic fluctuations in a periglacial environment, northern Sweden

Energy Technology Data Exchange (ETDEWEB)

Nyberg, R; Lindh, L [Lund Univ. (SE). Dept. of Physical Geography

1990-01-01

Goemorphic responses to climatic fluctuations in the periglacial mountain environment of northern Sweden, especially the Abisko mountains, are discussed. Although the frequency and magnitude of rapid mass movements are related to climatic conditions, the depositional patterns of the processes and the variable availability of source material complicate their use as climatic indicators. Possibly, debris flows and slushflows were frequent during the Little Ice Age, according to lichenometric dating of old deposits. Field observations suggest a fairly high frequency also during the last few decades. Boulder pavements, moraine-like ridges and glacial striae in front of major snowfields indicate these were previously larger and in some cases active as small glaciers perhaps in the cold beginning of the 1900's. During the warm 1920-30's snowpatches and glaciers, as well as permafrost mounds were affected by a general degeneration. Climatic inferences made from the mentioned features are still very crude. Tentatively, it is suggested that they are presently beginning to respond to the cooling trend affecting northern Scandinavia since about 1940. The anticipated impact of a greenhouse warming of the atmosphere has thus so far not been noticeable in this high latitude area. (authors).

An automated system for access to derived climate indices in support of ecological impacts assessments and resource management

Science.gov (United States)

Walker, J.; Morisette, J. T.; Talbert, C.; Blodgett, D. L.; Kunicki, T.

2012-12-01

A U.S. Geological Survey team is working with several providers to establish standard data services for the climate projection data they host. To meet the needs of climate adaptation science and landscape management communities, the team is establishing a set of climate index calculation algorithms that will consume data from various providers and provide directly useful data derivatives. Climate projections coming from various scenarios, modeling centers, and downscaling methods are increasing in number and size. Global change impact modeling and assessment, generally, requires inputs in the form of climate indices or values derived from raw climate projections. This requirement puts a large burden on a community not familiar with climate data formats, semantics, and processing techniques and requires storage capacity and computing resources out of the reach of most. In order to fully understand the implications of our best available climate projections, assessments must take into account an ensemble of climate projections and potentially a range of parameters for calculation of climate indices. These requirements around data access and processing are not unique from project to project, or even among projected climate data sets, pointing to the need for a reusable tool to generate climate indices. The U.S. Geological Survey has developed a pilot application and supporting web service framework that automates the generation of climate indices. The web service framework consists of standards-based data servers and a data integration broker. The resulting system allows data producers to publish and maintain ownership of their data and data consumers to access climate derivatives via a simple to use "data product ordering" workflow. Data access and processing is completed on enterprise "cloud" computing resources and only the relatively small, derived climate indices are delivered to the scientist or land manager. These services will assist the scientific and land

Reconstructing palaeo-environmental conditions in the Baltic: A multi-proxy comparison from IODP Site M0059 (Little Belt)

Science.gov (United States)

Kotthoff, Ulrich; Andrén, Thomas; Bauersachs, Thorsten; Fanget, Anne-Sophie; Granoszewski, Wojciech; Groeneveld, Jeroen; Krupinski, Nadine; Peyron, Odile; Stepanova, Anna; Cotterill, Carol

2015-04-01

Some of the largest marine environmental impacts from ongoing global climate change are occurring in continental shelf seas and enclosed basins, including severe oxygen depletion, intensifying stratification, and increasing temperatures. In order to predict future changes in water mass conditions, it is essential to reconstruct how these conditions have changed in the past. The brackish Baltic Sea is one of the largest semi-enclosed basins worldwide, and hence provides a unique opportunity to analyse past changes. IODP Expedition 347 recovered a unique set of long sediment cores from the Baltic Sea Basin which allow new high-resolution reconstructions. The application of existing and development of new proxies in such a setting is complicated, as environmental changes often occur on much faster time scales with much larger variations. Therefore, we present a comparison of commonly used proxies to reconstruct palaeoecosystems, -temperatures, and -salinity from IODP Site M0059 in the Little Belt. The age model for Site M0059 is based on 14C dating and biostratigraphic correlation with neighbouring terrestrial pollen records. The aim of our study is to reconstruct the development of the terrestrial and marine ecosystems in the research area and the related environmental conditions, and to identify potential limitations for specific proxies. Pollen is used as proxy for vegetation development in the hinterland of the southern Baltic Sea and as land/air-temperature proxies. By comparison with dinoflagellate cysts and green algae remains from the same samples, a direct land-sea comparison is provided. The application of the modern analogues technique to pollen assemblages has previously yielded precise results for late Pleistocene and Holocene datasets including specific information on seasonality, but pollen-based reconstructions for Northern Europe may be hampered by plant migration effects. Chironomid remains are used where possible as indicators for surface water

Analysis of nucleation events in the European boundary layer using the regional aerosol–climate model REMO-HAM with a solar radiation-driven OH-proxy

Directory of Open Access Journals (Sweden)

J.-P. Pietikäinen

2014-11-01

Full Text Available This work describes improvements in the regional aerosol–climate model REMO-HAM in order to simulate more realistically the process of atmospheric new particle formation (NPF. A new scheme was implemented to simulate OH radical concentrations using a proxy approach based on observations and also accounting for the effects of clouds upon OH concentrations. Second, the nucleation rate calculation was modified to directly simulate the formation rates of 3 nm particles, which removes some unnecessary steps in the formation rate calculations used earlier in the model. Using the updated model version, NPF over Europe was simulated for the periods 2003–2004 and 2008–2009. The statistics of the simulated particle formation events were subsequently compared to observations from 13 ground-based measurement sites. The new model shows improved agreement with the observed NPF rates compared to former versions and can simulate the event statistics realistically for most parts of Europe.

Aromatic acids in a Eurasian Arctic ice core: a 2600-year proxy record of biomass burning

Science.gov (United States)

Grieman, Mackenzie M.; Aydin, Murat; Fritzsche, Diedrich; McConnell, Joseph R.; Opel, Thomas; Sigl, Michael; Saltzman, Eric S.

2017-04-01

Wildfires and their emissions have significant impacts on ecosystems, climate, atmospheric chemistry, and carbon cycling. Well-dated proxy records are needed to study the long-term climatic controls on biomass burning and the associated climate feedbacks. There is a particular lack of information about long-term biomass burning variations in Siberia, the largest forested area in the Northern Hemisphere. In this study we report analyses of aromatic acids (vanillic and para-hydroxybenzoic acids) over the past 2600 years in the Eurasian Arctic Akademii Nauk ice core. These compounds are aerosol-borne, semi-volatile organic compounds derived from lignin combustion. The analyses were made using ion chromatography with electrospray mass spectrometric detection. The levels of these aromatic acids ranged from below the detection limit (0.01 to 0.05 ppb; 1 ppb = 1000 ng L-1) to about 1 ppb, with roughly 30 % of the samples above the detection limit. In the preindustrial late Holocene, highly elevated aromatic acid levels are observed during three distinct periods (650-300 BCE, 340-660 CE, and 1460-1660 CE). The timing of the two most recent periods coincides with the episodic pulsing of ice-rafted debris in the North Atlantic known as Bond events and a weakened Asian monsoon, suggesting a link between fires and large-scale climate variability on millennial timescales. Aromatic acid levels also are elevated during the onset of the industrial period from 1780 to 1860 CE, but with a different ratio of vanillic and para-hydroxybenzoic acid than is observed during the preindustrial period. This study provides the first millennial-scale record of aromatic acids. This study clearly demonstrates that coherent aromatic acid signals are recorded in polar ice cores that can be used as proxies for past trends in biomass burning.

Human rights of children with intellectual disabilities: comparing self-ratings and proxy ratings.

Science.gov (United States)

Huus, K; Granlund, M; Bornman, J; Lygnegård, F

2015-11-01

A child rights-based approach to research articulates well with Article 12 of the United Nations Convention on the Rights of the Child (CRC) and highlights the importance and value of including children's own views about aspects that concern them. The aim of this study is to compare children with intellectual disability's own ratings (as self-raters) to those of their primary caregivers (as proxy raters) regarding human rights of children. The study also aims to establish whether there is an inter-rater agreement between the self-raters and proxy raters concerning Maslow's hierarchy of needs. This study is nested in a larger study examining the human rights of children with intellectual disability in South Africa. In total, 162 children with intellectual disability from 11 schools across three provinces and their primary caregivers participated by answering parts of a Children's Rights Questionnaire (CRQ) developed by the researchers based on the United Nation's CRC. We compared the answers for six questions in the questionnaire that were addressed to self-raters (children) and proxy raters (primary caregivers) in the same way. Questions regarding basic needs, such as access to clean water or whether the child had food to eat at home, were answered similarly by self-raters and proxy raters. Larger differences were found when self-raters and proxy raters were asked about whether the child had things or friends to play with at home. Socio-economic variables seemed to affect whether self-raters and proxy raters answered similarly. The results underscore the importance of promoting children's rights to express themselves by considering the opinions of both the children as self-raters and their primary caregivers as proxy raters - not only the latter. The results indicate that it is especially important to include children's own voices when more complex needs are surveyed. Agreement between self- and proxy ratings could be affected by socio-economic circumstances. �

Comparison of several climate indices as inputs in modelling of the Baltic Sea runoff

Energy Technology Data Exchange (ETDEWEB)

Hanninen, J.; Vuorinen, I. [Turku Univ. (Finland). Archipelaco Research Inst.], e-mail: jari.hanninen@utu.fi

2012-11-01

Using Transfer function (TF) models, we have earlier presented a chain of events between changes in the North Atlantic Oscillation (NAO) and their oceanographical and ecological consequences in the Baltic Sea. Here we tested whether other climate indices as inputs would improve TF models, and our understanding of the Baltic Sea ecosystem. Besides NAO, the predictors were the Arctic Oscillation (AO), sea-level air pressures at Iceland (SLP), and wind speeds at Hoburg (Gotland). All indices produced good TF models when the total riverine runoff to the Baltic Sea was used as a modelling basis. AO was not applicable in all study areas, showing a delay of about half a year between climate and runoff events, connected with freezing and melting time of ice and snow in the northern catchment area of the Baltic Sea. NAO appeared to be most useful modelling tool as its area of applicability was the widest of the tested indices, and the time lag between climate and runoff events was the shortest. SLP and Hoburg wind speeds showed largely same results as NAO, but with smaller areal applicability. Thus AO and NAO were both mostly contributing to the general understanding of climate control of runoff events in the Baltic Sea ecosystem. (orig.)

Efficient Conditional Proxy Re-encryption with Chosen-Ciphertext Security

NARCIS (Netherlands)

Weng, Jiang; Yang, Yanjiang; Tang, Qiang; Deng, Robert H.; Bao, Feng

Recently, a variant of proxy re-encryption, named conditional proxy re-encryption (C-PRE), has been introduced. Compared with traditional proxy re-encryption, C-PRE enables the delegator to implement fine-grained delegation of decryption rights, and thus is more useful in many applications. In this

Optimizing TCP Performance over UMTS with Split TCP Proxy

DEFF Research Database (Denmark)

Hu, Liang; Dittmann, Lars

2009-01-01

. To cope with large delay bandwidth product, we propose a novel concept of split TCP proxy which is placed at GGSN between UNITS network and Internet. The split proxy divides the bandwidth delay product into two parts, resulting in two TCP connections with smaller bandwidth delay products which can...... be pipelined and thus operating at higher speeds. Simulation results show, the split TCP proxy can significantly improve the TCP performance in terms of RLC throughput under high bit rate DCH channel scenario (e.g.256 kbps). On the other hand, it only brings small performance improvement under low bit rate DCH...... scenario (e.g.64 kbps). Besides, the split TCP proxy brings more performance gain for downloading large files than downloading small ones. To the end, for the configuration of the split proxy, an aggressive initial TCP congestion window size (e.g. 10 MSS) at proxy is particularly useful for radio links...

Trends in global vegetation activity and climatic drivers indicate a decoupled response to climate change

DEFF Research Database (Denmark)

Schut, Antonius G T; Ivits, Eva; Conijn, Jacob G.

2015-01-01

Detailed understanding of a possible decoupling between climatic drivers of plant productivity and the response of ecosystems vegetation is required. We compared trends in six NDVI metrics (1982-2010) derived from the GIMMS3g dataset with modelled biomass productivity and assessed uncertainty...... in trend estimates. Annual total biomass weight (TBW) was calculated with the LINPAC model. Trends were determined using a simple linear regression, a Thiel-Sen medium slope and a piecewise regression (PWR) with two segments. Values of NDVI metrics were related to Net Primary Production (MODIS......-NPP) and TBWper biome and land-use type. The simple linear and Thiel-Sen trends did not differ much whereas PWR increased the fraction of explained variation, depending on the NDVI metric considered. A positive trend in TBW indicating more favorable climatic conditions was found for 24% of pixels on land...

Centennial-scale vegetation and climate changes in the Middle Atlas, Morocco: new insights from multi-proxy investigations at Lake Sidi Ali

Science.gov (United States)

Fletcher, William; Campbell, Jennifer; Joannin, Sebastien; Mischke, Steffen; Zielhofer, Christoph; de Batist, Marc; Mikdad, Abdes

2016-04-01

The karstic lakes of the Middle Atlas, Morocco, represent a valuable archive of environmental and climatic change for Northwest Africa. Here we present the results of centennial-scale palynological and charcoal analyses as part of a multiproxy palaeolimnological study of sediment cores from Lake Sidi Ali in the Middle Atlas, Morocco (33° 03 N, 05° 00 W; 2,080 m a.s.l.). Supported by absolute dating including 23 more than twenty AMS 14C dates on pollen concentrates, the record covers the entire Holocene and offers insights into vegetation and climate change at a regionally unprecedented centennial-scale. Pollen assemblages are dominated by steppic herbs, evergreen oaks (Quercus), junipers (Cupressaceae) and Atlantic cedar (Cedrus atlantica). A long-term evolution of the montane vegetation is recorded, reflecting progressive changes in the dominant arboreal taxa and leading to the full establishment of the emblematic cedar forests of the area during the mid-Holocene by 6000 cal BP. Orbital-scale changes in seasonality and growing season moisture availability linked to declining summer insolation are implicated, with a transition from (a) warm, dry summers associated with summer drought tolerant taxa especially evergreen Quercus, high algal productivity in the lake, and high background levels of microcharcoal reflecting distant fire activity during the early Holocene, to (b) cool, relatively humid summers with dominance of montane conifers, declining algal productivity in the lake, and episodic local fire activity during the mid- to late Holocene. Superimposed on the long-term environmental changes are recurrent centennial-scale fluctuations in vegetation composition, reflecting competitive dynamics between the major taxa, initially between steppic and arboreal elements, and later between the major tree taxa. Parallels with hydrological proxies including stable O and C isotopes suggest common responses to climatic drivers (fluctuations in moisture sources and

Interdecadal modulation of El Niño teleconnection on monsoon Asia climate over the past five centuries

Science.gov (United States)

Li, J.; Xie, S. P.

2017-12-01

The El Niño influence on monsoon Asia climate weakened during the mid-20th century and strenthened substantially after the late 1970s. Exploring the nature of such an interdecadal variation is constrained by short instrumental records. Here we synthesize the Indo-Pacific tree-rings and coral records to reconstruct monsoon Asia temperature and moisture change during the past five centuries, and show that the interdecadal modulation of El Niño teleconnection on monsoon Asia climate is a robust feature beyond the instrumenal era. Comparison with proxy El Niño records indicates that the El Niño-monsoon Asia climate teleconnection is controlled by interdecadal changes in ENSO variance, with strong (weak) teleconnection in periods of high (low) variance, respectively.

Reconstructing Holocene palaeo-environmental conditions in the Baltic: A multi-proxy comparison from the Little Belt (IODP Expedition 347, Site M0059)

Science.gov (United States)

Kotthoff, Ulrich; Andrén, Elinor; Andrén, Thomas; Ash, Jeanine; Bauersachs, Thorsten; Fanget, Anne-Sophie; Granoszewski, Wojciech; Groeneveld, Jeroen; Krupinski, Nadine; Peyron, Odile; Slomp, Caroline; Stepanova, Anna; Warnock, Jonathan; van Helmond, Niels; Expedition 347 Science Party

2016-04-01

Some of the largest marine environmental impacts from ongoing global climate change are occurring in continental shelf seas and enclosed basins, including severe oxygen depletion, intensifying stratification, and increasing temperatures. In order to predict future changes in water mass conditions, it is essential to reconstruct how these conditions have changed in the past against the background of climate changes. The brackish Baltic Sea is one of the largest semi-enclosed basins worldwide, and its sediment records provide a unique opportunity to analyse palaeo-environmental and climate change in central and northern Europe. IODP Expedition 347 recovered an exceptional set of sediment cores from the Baltic Sea which allow high-resolution reconstructions in unprecedented quality. We present a comparison of commonly-used proxies to reconstruct palaeoecosystems, -temperatures, and -salinity from IODP Site M0059 in the Little Belt over the past ˜8000 years. Our aim is to reconstruct the development of the terrestrial and marine ecosystems in the research area and the related environmental conditions, and to identify potential limitations of individual proxies. The age model for Site M0059 is based on 14Cdating, biostratigraphic correlation with neighbouring terrestrial pollen records, and sediment stratigraphy. Sedimentary organic carbon content and the bulk elemental composition have been measured, and can be used to determine the depositional environment and degree of oxygen depletion (e.g., Mo, Corg/Ptot). Pollen is used as proxy for vegetation development in the hinterland of the southern Baltic Sea and as a land/air-temperature proxy. Comparison with dinoflagellate cysts, insect remains, and green algae remains from the same samples provides a direct land-sea comparison. The application of the modern analogues technique to pollen assemblages has previously yielded precise results for late Pleistocene and Holocene datasets, including specific information on

Development of DEMQOL-U and DEMQOL-PROXY-U: generation of preference-based indices from DEMQOL and DEMQOL-PROXY for use in economic evaluation.

Science.gov (United States)

Mulhern, B; Rowen, D; Brazier, J; Smith, S; Romeo, R; Tait, R; Watchurst, C; Chua, K-C; Loftus, V; Young, T; Lamping, D; Knapp, M; Howard, R; Banerjee, S

2013-02-01

Dementia is one of the most common and serious disorders in later life and the economic and personal cost of caring for people with dementia is immense. There is a need to be able to evaluate interventions in dementia using cost-effectiveness analyses, but the generic preference-based measures typically used to measure effectiveness do not work well in dementia. Existing dementia-specific measures can effectively measure health-related quality of life but in their current form cannot be used directly to inform cost-effectiveness analysis using quality-adjusted life-years as the measure of effectiveness. The aim was to develop two brief health-state classifications, one from DEMQOL and one from DEMQOL-Proxy, to generate health states amenable to valuation. These classification systems consisted of items taken from DEMQOL and DEMQOL-Proxy so they can be derived from any study that has used these instruments. In the first stage of the study we used a large, clinically representative sample aggregated from two sources: a sample of patients and carers attending a memory service in south London and a sample of patients and carers from other community services in south London. This included 644 people with a diagnosis of mild/moderate dementia and 689 carers of those with mild/moderate dementia. For the valuation study, the general population sample of 600 respondents was drawn to be representative of the UK general population. Households were sampled in urban and rural areas in northern England and balanced to the UK population according to geodemographic profiles. In the patient/carer valuation study we interviewed a sample of 71 people with mild dementia and 71 family carers drawn from a memory service in south London. Finally, the instruments derived were applied to data from the HTA-SADD (Study of Antidepressants for Depression in Dementia) trial. This was a complex multiphase study with four linked phases: phase 1 - derivation of the health-state classification

Maximum rates of climate change are systematically underestimated in the geological record.

Science.gov (United States)

Kemp, David B; Eichenseer, Kilian; Kiessling, Wolfgang

2015-11-10

Recently observed rates of environmental change are typically much higher than those inferred for the geological past. At the same time, the magnitudes of ancient changes were often substantially greater than those established in recent history. The most pertinent disparity, however, between recent and geological rates is the timespan over which the rates are measured, which typically differ by several orders of magnitude. Here we show that rates of marked temperature changes inferred from proxy data in Earth history scale with measurement timespan as an approximate power law across nearly six orders of magnitude (10(2) to >10(7) years). This scaling reveals how climate signals measured in the geological record alias transient variability, even during the most pronounced climatic perturbations of the Phanerozoic. Our findings indicate that the true attainable pace of climate change on timescales of greatest societal relevance is underestimated in geological archives.

Family factors in end-of-life decision-making: family conflict and proxy relationship.

Science.gov (United States)

Parks, Susan Mockus; Winter, Laraine; Santana, Abbie J; Parker, Barbara; Diamond, James J; Rose, Molly; Myers, Ronald E

2011-02-01

Few studies have examined proxy decision-making regarding end-of-life treatment decisions. Proxy accuracy is defined as whether proxy treatment choices are consistent with the expressed wishes of their index elder. The purpose of this study was to examine proxy accuracy in relation to two family factors that may influence proxy accuracy: perceived family conflict and type of elder-proxy relationship. Telephone interviews with 202 community-dwelling elders and their proxy decision makers were conducted including the Life-Support Preferences Questionnaire (LSPQ), and a measure of family conflict, and sociodemographic characteristics, including type of relationship. Elder-proxy accuracy was associated with the type of elder-proxy relationship. Adult children demonstrated the lowest elder-proxy accuracy and spousal proxies the highest elder-proxy accuracy. Elder-proxy accuracy was associated with family conflict. Proxies reporting higher family conflict had lower elder-proxy accuracy. No interaction between family conflict and relationship type was revealed. Spousal proxies were more accurate in their substituted judgment than adult children, and proxies who perceive higher degree of family conflict tended to be less accurate than those with lower family conflict. Health care providers should be aware of these family factors when discussing advance care planning.

Modified climate with long term memory in tree ring proxies

Czech Academy of Sciences Publication Activity Database

Zhang, H.; Yuan, N.; Esper, J.; Werner, J. P.; Xoplaki, E.; Büntgen, Ulf; Treydte, K.; Luterbacher, J.

2015-01-01

Roč. 10, č. 8 (2015), č. článku 084020. ISSN 1748-9326 Institutional support: RVO:67179843 Keywords : surface-temperature * northern-hemisphere * china * variability * persistence * precipitation * fluctuations * millennium * rainfall * model * climate reconstructions * tree-ring width * maximum latewood density * frequency domains Subject RIV: EH - Ecology, Behaviour Impact factor: 4.134, year: 2015

Opportunities and limitations related to the application of plant-derived lipid molecular proxies in soil science

Directory of Open Access Journals (Sweden)

B. Jansen

2017-11-01

Full Text Available The application of lipids in soils as molecular proxies, also often referred to as biomarkers, has dramatically increased in the last decades. Applications range from inferring changes in past vegetation composition, climate, and/or human presence to unraveling the input and turnover of soil organic matter (SOM. The molecules used are extractable and non-extractable lipids, including ester-bound lipids. In addition, the carbon or hydrogen isotopic composition of such molecules is used. While holding great promise, the application of soil lipids as molecular proxies comes with several constraining factors, the most important of which are (i variability in the molecular composition of plant-derived organic matter both internally and between individual plants, (ii variability in (the relative contribution of input pathways into the soil, and (iii the transformation and/or (selective degradation of (some of the molecules once present in the soil. Unfortunately, the information about such constraining factors and their impact on the applicability of molecular proxies is fragmented and scattered. The purpose of this study is to provide a critical review of the current state of knowledge with respect to the applicability of molecular proxies in soil science, specifically focusing on the factors constraining such applicability. Variability in genetic, ontogenetic, and environmental factors influences plant n-alkane patterns in such a way that no unique compounds or specific molecular proxies pointing to, for example, plant community differences or environmental influences, exist. Other components, such as n-alcohols, n-fatty acids, and cutin- and suberin-derived monomers, have received far less attention in this respect. Furthermore, there is a high diversity of input pathways offering both opportunities and limitations for the use of molecular proxies at the same time. New modeling approaches might offer a possibility to unravel such mixed input

Trends in Global Vegetation Activity and Climatic Drivers Indicate a Decoupled Response to Climate Change.

Directory of Open Access Journals (Sweden)

Antonius G T Schut

Full Text Available Detailed understanding of a possible decoupling between climatic drivers of plant productivity and the response of ecosystems vegetation is required. We compared trends in six NDVI metrics (1982-2010 derived from the GIMMS3g dataset with modelled biomass productivity and assessed uncertainty in trend estimates. Annual total biomass weight (TBW was calculated with the LINPAC model. Trends were determined using a simple linear regression, a Thiel-Sen medium slope and a piecewise regression (PWR with two segments. Values of NDVI metrics were related to Net Primary Production (MODIS-NPP and TBW per biome and land-use type. The simple linear and Thiel-Sen trends did not differ much whereas PWR increased the fraction of explained variation, depending on the NDVI metric considered. A positive trend in TBW indicating more favorable climatic conditions was found for 24% of pixels on land, and for 5% a negative trend. A decoupled trend, indicating positive TBW trends and monotonic negative or segmented and negative NDVI trends, was observed for 17-36% of all productive areas depending on the NDVI metric used. For only 1-2% of all pixels in productive areas, a diverging and greening trend was found despite a strong negative trend in TBW. The choice of NDVI metric used strongly affected outcomes on regional scales and differences in the fraction of explained variation in MODIS-NPP between biomes were large, and a combination of NDVI metrics is recommended for global studies. We have found an increasing difference between trends in climatic drivers and observed NDVI for large parts of the globe. Our findings suggest that future scenarios must consider impacts of constraints on plant growth such as extremes in weather and nutrient availability to predict changes in NPP and CO2 sequestration capacity.

Evaluation of Organic Proxies for Quantifying Past Primary Productivity

Science.gov (United States)

Raja, M.; Rosell-Melé, A.; Galbraith, E.

2017-12-01

Ocean primary productivity is a key element of the marine carbon cycle. However, its quantitative reconstruction in the past relies on the use of biogeochemical models as the available proxy approaches are qualitative at best. Here, we present an approach that evaluates the use of phytoplanktonic biomarkers (i.e. chlorins and alkenones) as quantitative proxies to reconstruct past changes in marine productivity. We compare biomarkers contents in a global suite of core-top sediments to sea-surface chlorophyll-a abundance estimated by satellites over the last 20 years, and the results are compared to total organic carbon (TOC). We also assess satellite data and detect satellite limitations and biases due to the complexity of optical properties and the actual defined algorithms. Our findings show that sedimentary chlorins can be used to track total sea-surface chlorophyll-a abundance as an indicator for past primary productivity. However, degradation processes restrict the application of this proxy to concentrations below a threshold value (1µg/g). Below this threshold, chlorins are a useful tool to identify reducing conditions when used as part of a multiproxy approach to assess redox sedimentary conditions (e.g. using Re, U). This is based on the link between anoxic/disoxic conditions and the flux of organic matter from the sea-surface to the sediments. We also show that TOC is less accurate than chlorins for estimating sea-surface chlorophyll-a due to the contribution of terrigenous organic matter, and the different degradation pathways of all organic compounds that TOC includes. Alkenones concentration also relates to primary productivity, but they are constrained by different processes in different regions. In conclusion, as lons as specific constraints are taken into account, our study evaluates the use of chlorins and alkenones as quantitative proxies of past primary productivity, with more accuracy than by using TOC.

Comparison of Geochemical, Grain-Size, and Magnetic Proxies for Rock Flour and Ice- Rafted Debris in the Late Pleistocene Mono Basin, CA

Science.gov (United States)

Zimmerman, S. H.; Hemming, S. R.; Kent, D. V.

2008-12-01

Advance and retreat of mountain glaciers are important indicators of climate variability, but the most direct proxy record, mapping and dating of moraines, is by nature discontinous. The Sierra Nevada form the western boundary of the Mono Lake basin, and the proximity of the large Pleistocene lake to the glacial canyons of the Sierra presents a rare opportunity to examine glacial variability in a continuous, well-dated lacustrine sequence. We have applied a geochemical proxy for rock flour to the glacial silts of the late Pleistocene Wilson Creek Formation, but because it is time- and sample-intensive, another method is required for a high-resolution record. Previous microscopic examination, thermomagnetic measurements, XRD analysis, and new isothermal remnant magnetization (IRM) acquisition curves show that the magnetic mineralogy is dominated by fine-grained, unaltered magnetite. Bulk measurements show strong susceptibility (mean ~ 16 x 10- 6 m3/kg) and remanent magnetization (mean IRM ~ 10-2 Am2/kg) compared to diluting components (carbonate, smectite, rhyolitic ash). The Wilson Creek type section sediments also contain a coarse lithic fraction, quantified by counting the >2cm clasts in outcrop and the >425 μm fraction in the bulk sediment. Susceptibility, IRM, and ARM (anhysteretic remnant magnetization) are quite similar throughout the type section, with the abundance of coarse lithic fraction correlative to the ratio k/IRM. Because the magnetic fraction of the rock flour is fine-grained magnetite, IRM should capture the changes in concentration of flour through time, and the major features of the (low-resolution) geochemical flour proxy record are identifiable in the IRM record. Flux-correction of the IRM results in a rock flour proxy record with major peaks between 36 and 48 ka, similar to a rock flour record from neighboring Owens Lake. This regional glacial signal contrasts with peaks in coarse lithics between 58 and 68 ka in the Wilson Creek record

Pollen-based reconstruction of Holocene climate variability in the Eifel region evaluated with stable isotopes

Science.gov (United States)

Kühl, Norbert; Moschen, Robert; Wagner, Stefanie

2010-05-01

Pollen as well as stable isotopes have great potential as climate proxy data. While variability in these proxy data is frequently assumed to reflect climate variability, other factors than climate, including human impact and statistical noise, can often not be excluded as primary cause for the observed variability. Multiproxy studies offer the opportunity to test different drivers by providing different lines of evidence for environmental change such as climate variability and human impact. In this multiproxy study we use pollen and peat humification to evaluate to which extent stable oxygen and carbon isotope series from the peat bog "Dürres Maar" reflect human impact rather than climate variability. For times before strong anthropogenic vegetation change, isotope series from Dürres Maar were used to validate quantitative reconstructions based on pollen. Our study site is the kettle hole peat bog "Dürres Maar" in the Eifel low mountain range, Germany (450m asl), which grew 12m during the last 10,000 years. Pollen was analysed with a sum of at least 1000 terrestrial pollen grains throughout the profile to minimize statistical effects on the reconstructions. A recently developed probabilistic indicator taxa method ("pdf-method") was used for the quantitative climate estimates (January and July temperature) based on pollen. For isotope analysis, attention was given to use monospecific Sphagnum leaves whenever possible, reducing the potential of a species effect and any potential artefact that can originate from selective degradation of different morphological parts of Sphagnum plants (Moschen et al., 2009). Pollen at "Dürres Maar" reflect the variable and partly strong human impact on vegetation during the last 4000 years. Stable isotope time series were apparently not influenced by human impact at this site. This highlights the potential of stable isotope investigations from peat for climatic interpretation, because stable isotope series from lacustrine

Impacts of Climate Change on the Collapse of Lowland Maya Civilization

Science.gov (United States)

Douglas, Peter M. J.; Demarest, Arthur A.; Brenner, Mark; Canuto, Marcello A.

2016-06-01

Paleoclimatologists have discovered abundant evidence that droughts coincided with collapse of the Lowland Classic Maya civilization, and some argue that climate change contributed to societal disintegration. Many archaeologists, however, maintain that drought cannot explain the timing or complex nature of societal changes at the end of the Classic Period, between the eighth and eleventh centuries ce. This review presents a compilation of climate proxy data indicating that droughts in the ninth to eleventh century were the most severe and frequent in Maya prehistory. Comparison with recent archaeological evidence, however, indicates an earlier beginning for complex economic and political processes that led to the disintegration of states in the southern region of the Maya lowlands that precedes major droughts. Nonetheless, drought clearly contributed to the unusual severity of the Classic Maya collapse, and helped to inhibit the type of recovery seen in earlier periods of Maya prehistory. In the drier northern Maya Lowlands, a later political collapse at ca. 1000 ce appears to be related to ongoing extreme drought. Future interdisciplinary research should use more refined climatological and archaeological data to examine the relationship between climate and social processes throughout the entirety of Maya prehistory.

Attaining provenance proxies from OSL and TL sensitivities: Coupling with grain size and heavy minerals data from southern Brazilian coastal sediments

International Nuclear Information System (INIS)

Zular, André; Sawakuchi, André O.; Guedes, Carlos C.F.; Giannini, Paulo C.F.

2015-01-01

In the São Francisco do Sul (SFS) barrier in southern Brazil, the optically stimulated luminescence (OSL) and thermoluminescence (TL) sensitivities of coastal sands vary according to geomorphological units. Sands from older beach ridges (ages older than 2000 years ago) show higher OSL and TL sensitivities than younger units (ages younger than 2000 years). Geomorphological units in the SFS attest to changes in provenance as a result of a coastal climate shift evidenced through grain size and heavy mineral analysis. We argue that in the SFS barrier sands, OSL and TL sensitivity signals provide an additional proxy to climate events and can be used as an alternative method to assess changes in provenance and tracking source-to-sink systems to monitor past and future environmental changes. - Highlights: • OSL and TL sensitivities are confronted with grain size and heavy minerals data. • We report OSL and 110 °C TL sensitivities as provenance proxies. • 110 °C TL sensitivity outlines environmental changes better than OSL sensitivity data.

Climate variability in the subarctic area for the last 2 millennia

Directory of Open Access Journals (Sweden)

M. Nicolle

2018-01-01

Full Text Available To put recent climate change in perspective, it is necessary to extend the instrumental climate records with proxy data from paleoclimate archives. Arctic climate variability for the last 2 millennia has been investigated using statistical and signal analyses from three regionally averaged records from the North Atlantic, Siberia and Alaska based on many types of proxy data archived in the Arctic 2k database v1.1.1. In the North Atlantic and Alaska, the major climatic trend is characterized by long-term cooling interrupted by recent warming that started at the beginning of the 19th century. This cooling is visible in the Siberian region at two sites, warming at the others. The cooling of the Little Ice Age (LIA was identified from the individual series, but it is characterized by wide-range spatial and temporal expression of climate variability, in contrary to the Medieval Climate Anomaly. The LIA started at the earliest by around AD 1200 and ended at the latest in the middle of the 20th century. The widespread temporal coverage of the LIA did not show regional consistency or particular spatial distribution and did not show a relationship with archive or proxy type either. A focus on the last 2 centuries shows a recent warming characterized by a well-marked warming trend parallel with increasing greenhouse gas emissions. It also shows a multidecadal variability likely due to natural processes acting on the internal climate system on a regional scale. A ∼ 16–30-year cycle is found in Alaska and seems to be linked to the Pacific Decadal Oscillation, whereas ∼ 20–30- and ∼ 50–90-year periodicities characterize the North Atlantic climate variability, likely in relation with the Atlantic Multidecadal Oscillation. These regional features are probably linked to the sea ice cover fluctuations through ice–temperature positive feedback.

Reliability of flipper-banded penguins as indicators of climate change.

Science.gov (United States)

Saraux, Claire; Le Bohec, Céline; Durant, Joël M; Viblanc, Vincent A; Gauthier-Clerc, Michel; Beaune, David; Park, Young-Hyang; Yoccoz, Nigel G; Stenseth, Nils C; Le Maho, Yvon

2011-01-13

In 2007, the Intergovernmental Panel on Climate Change highlighted an urgent need to assess the responses of marine ecosystems to climate change. Because they lie in a high-latitude region, the Southern Ocean ecosystems are expected to be strongly affected by global warming. Using top predators of this highly productive ocean (such as penguins) as integrative indicators may help us assess the impacts of climate change on marine ecosystems. Yet most available information on penguin population dynamics is based on the controversial use of flipper banding. Although some reports have found the effects of flipper bands to be deleterious, some short-term (one-year) studies have concluded otherwise, resulting in the continuation of extensive banding schemes and the use of data sets thus collected to predict climate impact on natural populations. Here we show that banding of free-ranging king penguins (Aptenodytes patagonicus) impairs both survival and reproduction, ultimately affecting population growth rate. Over the course of a 10-year longitudinal study, banded birds produced 41% [corrected] fewer chicks and had a survival rate 16 percentage points [corrected] lower than non-banded birds, demonstrating a massive long-term impact of banding and thus refuting the assumption that birds will ultimately adapt to being banded. Indeed, banded birds still arrived later for breeding at the study site and had longer foraging trips even after 10 years. One of our major findings is that responses of flipper-banded penguins to climate variability (that is, changes in sea surface temperature and in the Southern Oscillation index) differ from those of non-banded birds. We show that only long-term investigations may allow an evaluation of the impact of flipper bands and that every major life-history trait can be affected, calling into question the banding schemes still going on. In addition, our understanding of the effects of climate change on marine ecosystems based on flipper

Effects of climate change on agroclimatic indices in rainfed wheat production areas of Iran

Directory of Open Access Journals (Sweden)

mehdi nassiri mahalati

2009-06-01

Full Text Available Despite the importance of all climatic parameters for crop growth and productivity, temperature and rainfall are more crucial compared to others and almost all climatic and agroclimatic indices are based on these two variables. Climate change will lead to variation in agroclimatic indices and evaluation of this variation is a key to study crop response to future climatic conditions. Length of growing period (LGP and rainfall deficit index could be used as indictors for assessment of potential impact of climate change of rainfed systems. To study this impact long-term weather data of main rainfed wheat production areas of Iran were collected. UKMO general circulation model was used for perdiction of climatic parameters of selected stations for years 2025 and 2050 based on pre defined scenarios of IPCC for this target years. LGP, length of dry season and rainfall deficit index were calculated from present data and the generated data for target years. The results showed that LGP based on temperature would be increased in all rainfed areas of country. However, including the water availability in the calculation was led to a lowered LGP. Reduction of LGP for the studied stations was in the range of 8-36 and 19-55 days for years 2025 and 2050, respectively. Rainfall deficit index for 2025 and 2050 was varied, respectively at 8.3-17.7 and 21.1-32.3 mm. It was estimated that under climatic condition of years 2025 and 2050 the cultivated areas in the main rainfed production regions of the country would be reduced by 16-25 and 23-33%, respectively.

Climate sensitivity of marine energy

International Nuclear Information System (INIS)

Harrison, G.P.; Wallace, A.R.

2005-01-01

Marine energy has a significant role to play in lowering carbon emissions within the energy sector. Paradoxically, it may be susceptible to changes in climate that will result from rising carbon emissions. Wind patterns are expected to change and this will alter wave regimes. Despite a lack of definite proof of a link to global warming, wind and wave conditions have been changing over the past few decades. Changes in the wind and wave climate will affect offshore wind and wave energy conversion: where the resource is constrained, production and economic performance may suffer; alternatively, stormier climates may create survival issues. Here, a relatively simple sensitivity study is used to quantify how changes in mean wind speed - as a proxy for wider climate change - influence wind and wave energy production and economics. (author)

Inland Water Temperature: An Ideal Indicator for the National Climate Assessment

Science.gov (United States)

Hook, S. J.; Lenters, J. D.; O'Reilly, C.; Healey, N. C.

2014-12-01

NASA is a significant contributor to the U.S. National Climate Assessment (NCA), which is a central component of the 2012-2022 U.S. Global Change Research Program Strategic Plan. The NCA has identified the need for indicators that provide a clear, concise way of communicating to NCA audiences about not only the status and trends of physical drivers of the climate system, but also the ecological and socioeconomic impacts, vulnerabilities, and responses to those drivers. We are using thermal infrared satellite data in conjunction with in situ measurements to produce water temperatures for all the large inland water bodies in North America for potential use as an indicator for the NCA. Recent studies have revealed significant warming of inland waters throughout the world. The observed rate of warming is - in many cases - greater than that of the ambient air temperature. These rapid, unprecedented changes in inland water temperatures have profound implications for lake hydrodynamics, productivity, and biotic communities. Scientists are just beginning to understand the global extent, regional patterns, physical mechanisms, and ecological consequences of lake warming. As part of our earlier studies we have collected thermal infrared satellite data from those satellite sensors that provide long-term and frequent spaceborne thermal infrared measurements of inland waters including ATSR, AVHRR, and MODIS and used these to examine trends in water surface temperature for approximately 100 of the largest inland water bodies in the world. We are now extending this work to generate temperature time-series of all North American inland water bodies that are sufficiently large to be studied using 1km resolution satellite data for the last 3 decades. These data are then being related to changes in the surface air temperature and compared with regional trends in water surface temperature derived from CMIP5/IPCC model simulations/projections to better predict future temperature changes

Sensitivity of wetland hydrology to external climate forcing in central Florida

Science.gov (United States)

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

2015-11-01

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

Revisiting the effects of hydrodynamic sorting and sedimentary recycling on chemical weathering indices

Science.gov (United States)

Guo, Yulong; Yang, Shouye; Su, Ni; Li, Chao; Yin, Ping; Wang, Zhongbo

2018-04-01

Although the proxies based on elemental geochemistry of siliciclastic sediments have been well developed to indicate the intensity of chemical weathering in various catchments, their geological indications and limitations, and especially how the differentiation of minerals and sediment grain size influences the applications of these proxies needs more clarification. This paper investigates the interactive effects of weathering, hydraulic sorting and sedimentary recycling on river sediment chemistry, and further validates the application of various weathering indices by measuring mineralogical and geochemical compositions of bank sediments and suspended particulate matters (SPMs) from five rivers in East China bearing various sizes, geologic settings and climatic regimes. For a specific river, the silicate weathering intensity registered in the fine SPMs is systematically stronger than that in the coarse-grained bank sediments. Most of the weathering indices not only reflect the integrated weathering history of various catchments but also depend on hydraulic sorting effect during sediment transport and depositional processes. The correlation between CIA (chemical index of alteration) and WIP (weathering index of Parker) offers an approach to predict the weathering trends of the fine SPMs, coarse bank sediments and recycled sediments under the influence of quartz dilution. To minimize the effects of hydrodynamic sorting and sedimentary recycling, we suggest that the fine sediments (e.g. SPMs and <2 μm fraction of bank sediments) in rivers can better reflect the average of present-day weathering crust in catchments and the weathered terrigenous materials into marginal seas and oceans.

Lichen-based indices to quantify responses to climate and air pollution across northeastern U.S.A

Science.gov (United States)

Susan Will-Wolf; Sarah Jovan; Peter Neitlich; JeriLynn E. Peck; Roger Rosentreter

2015-01-01

Lichens are known to be indicators for air quality; they also respond to climate. We developed indices for lichen response to climate and air quality in forests across the northeastern United States of America (U.S.A.), using 218–250 plot surveys with 145–161 macrolichen taxa from the Forest Inventory and Analysis (FIA) Program of the U.S. Department of Agriculture,...

Bridging long proxy data time series and instrumental observation in the Virtual Institute of Integrated Climate and Landscape Evolution Analyses - ICLEA

Science.gov (United States)

Schwab, Markus J.; Brauer, Achim; Błaszkiewicz, Mirosław; Raab, Thomas; Wilmking, Martin

2015-04-01

climate and landscape evolution in an historical cultural landscape extending from northeastern Germany into northwestern Poland. The northern-central European lowlands will be facilitated as a natural laboratory providing an ideal case for utilizing a systematic and holistic approach. In ICLEA five complementary work packages (WP) are established according to the key research aspects. WP 1 focused on monitoring mainly hydrology and soil moisture as well as meteorological parameters. WP 2 is linking present day and future monitoring data with the most recent past through analyzing satellite images. This WP will further provide larger spatial scales. WP 3-5 focus on different natural archives to obtain a broad variety of high quality proxy data. Tree rings provide sub-seasonal data for the last centuries up to few millennia, varved lake sediments cover the entire research time interval at seasonal to decadal resolution and palaeosoils and geomorphological features also cover the entire period but not continuously and with lower resolution. Complementary information, like climate, tree ecophysiological and limnological data etc., are provided by cooperation with associated partners. Further information about ICLEA: www.iclea.de

Perbandingan proxy pada linux dan windows untuk mempercepat browsing website

Directory of Open Access Journals (Sweden)

Dafwen Toresa

2017-05-01

Full Text Available AbstrakPada saat ini sangat banyak organisasi, baik pendidikan, pemerintahan,  maupun perusahaan swasta berusaha membatasi akses para pengguna ke internet dengan alasan bandwidth yang dimiliki mulai terasa lambat ketika para penggunanya mulai banyak yang melakukan browsing ke internet. Mempercepat akses browsing menjadi perhatian utama dengan memanfaatkan teknologi Proxy server. Penggunaan proxy server perlu mempertimbangkan sistem operasi pada server dan tool yang digunakan belum diketahui performansi terbaiknya pada sistem operasi apa.  Untuk itu dirasa perlu untuk menganalisis performan Proxy server pada sistem operasi berbeda yaitu Sistem Operasi Linux dengan tools Squid  dan Sistem Operasi Windows dengan tool Winroute. Kajian ini dilakukan untuk mengetahui perbandingan kecepatan browsing dari komputer pengguna (client. Browser yang digunakan di komputer pengguna adalah Mozilla Firefox. Penelitian ini menggunakan 2 komputer klien dengan pengujian masing-masingnya 5 kali pengujian pengaksesan/browsing web yang dituju melalui proxy server. Dari hasil pengujian yang dilakukan, diperoleh kesimpulan bahwa penerapan proxy server di sistem operasi linux dengan tools squid lebih cepat browsing dari klien menggunakan web browser yang sama dan komputer klien yang berbeda dari pada proxy server sistem operasi windows dengan tools winroute.  Kata kunci: Proxy, Bandwidth, Browsing, Squid, Winroute AbstractAt this time very many organizations, both education, government, and private companies try to limit the access of users to the internet on the grounds that the bandwidth owned began to feel slow when the users began to do a lot of browsing to the internet. Speed up browsing access is a major concern by utilizing Proxy server technology. The use of proxy servers need to consider the operating system on the server and the tool used is not yet known the best performance on what operating system. For that it is necessary to analyze Performance Proxy

A regime shift in the Sun-Climate connection with the end of the Medieval Climate Anomaly.

Science.gov (United States)

Smirnov, D A; Breitenbach, S F M; Feulner, G; Lechleitner, F A; Prufer, K M; Baldini, J U L; Marwan, N; Kurths, J

2017-09-11

Understanding the influence of changes in solar activity on Earth's climate and distinguishing it from other forcings, such as volcanic activity, remains a major challenge for palaeoclimatology. This problem is best approached by investigating how these variables influenced past climate conditions as recorded in high precision paleoclimate archives. In particular, determining if the climate system response to these forcings changes through time is critical. Here we use the Wiener-Granger causality approach along with well-established cross-correlation analysis to investigate the causal relationship between solar activity, volcanic forcing, and climate as reflected in well-established Intertropical Convergence Zone (ITCZ) rainfall proxy records from Yok Balum Cave, southern Belize. Our analysis reveals a consistent influence of volcanic activity on regional Central American climate over the last two millennia. However, the coupling between solar variability and local climate varied with time, with a regime shift around 1000-1300 CE after which the solar-climate coupling weakened considerably.

Deriving evaluation indicators for knowledge transfer and dialogue processes in the context of climate research

Science.gov (United States)

Treffeisen, Renate; Grosfeld, Klaus; Kuhlmann, Franziska

2017-12-01

Knowledge transfer and dialogue processes in the field of climate science have captured intensive attention in recent years as being an important part of research activities. Therefore, the demand and pressure to develop a set of indicators for the evaluation of different activities in this field have increased, too. Research institutes are being asked more and more to build up structures in order to map these activities and, thus, are obliged to demonstrate the success of these efforts. This paper aims to serve as an input to stimulate further reflection on the field of evaluation of knowledge transfer and dialogue processes in the context of climate sciences. The work performed in this paper is embedded in the efforts of the German Helmholtz Association in the research field of earth and environment and is driven by the need to apply suitable indicators for knowledge transfer and dialogue processes in climate research center evaluations. We carry out a comparative analysis of three long-term activities and derive a set of indicators for measuring their output and outcome by balancing the wide diversity and range of activity contents as well as the different tools to realize them. The case examples are based on activities which are part of the regional Helmholtz Climate Initiative Regional Climate Change (REKLIM) and the Climate Office for Polar Regions and Sea Level Rise at the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research. Both institutional units have been working on a wide range of different knowledge transfer and dialogue processes since 2008/2009. We demonstrate that indicators for the evaluation must be based on the unique objectives of the individual activities and the framework they are embedded in (e.g., research foci which provide the background for the performed knowledge transfer and dialogue processes) but can partly be classified in a principle two-dimensional scheme. This scheme might serve as a usable basis for climate

Handwashing in 51 Countries: Analysis of Proxy Measures of Handwashing Behavior in Multiple Indicator Cluster Surveys and Demographic and Health Surveys, 2010-2013.

Science.gov (United States)

Kumar, Swapna; Loughnan, Libbet; Luyendijk, Rolf; Hernandez, Orlando; Weinger, Merri; Arnold, Fred; Ram, Pavani K

2017-08-01

In 2009, a common set of questions addressing handwashing behavior was introduced into nationally representative Demographic and Health Surveys (DHS) and Multiple Indicator Cluster Surveys (MICS), providing large amounts of comparable data from numerous countries worldwide. The objective of this analysis is to describe global handwashing patterns using two proxy indicators for handwashing behavior from 51 DHS and MICS surveys conducted in 2010-2013: availability of soap anywhere in the dwelling and access to a handwashing place with soap and water. Data were also examined across geographic regions, wealth quintiles, and rural versus urban settings. We found large disparities for both indicators across regions, and even among countries within the same World Health Organization region. Within countries, households in lower wealth quintiles and in rural areas were less likely to have soap anywhere in the dwelling and at designated handwashing locations than households in higher wealth quintiles and urban areas. In addition, disparities existed among various geographic regions within countries. This analysis demonstrates the need to promote access to handwashing materials and placement at handwashing locations in the dwelling, particularly in poorer, rural areas where children are more vulnerable to handwashing-preventable syndromes such as pneumonia and diarrhea.

Strong climate coupling of terrestrial and marine environments in the Miocene of northwest Europe

NARCIS (Netherlands)

Donders, T.H.; Weijers, J.W.H.; Munsterman, D.K.; Kloosterboer-van Hoeve, M.L.; Buckles, L.K.; Pancost, R.D.; Schouten, S.; Sinninghe Damsté, J.S.; Brinkhuis, H.

2009-01-01

A palynological and organic geochemical record from a shallow marine paleoenvironmental setting in SE Netherlands documents the coupled marine and terrestrial climate evolution from the late Burdigalian (∼ 17 Ma) through the early Zanclean (∼ 4.5 Ma). Proxy climate records show several coeval

Climatic impact of volcanic eruptions

Science.gov (United States)

Rampino, Michael R.

1991-01-01

Studies have attempted to 'isolate' the volcanic signal in noisy temperature data. This assumes that it is possible to isolate a distinct volcanic signal in a record that may have a combination of forcings (ENSO, solar variability, random fluctuations, volcanism) that all interact. The key to discovering the greatest effects of volcanoes on short-term climate may be to concentrate on temperatures in regions where the effects of aerosol clouds may be amplified by perturbed atmospheric circulation patterns. This is especially true in subpolar and midlatitude areas affected by changes in the position of the polar front. Such climatic perturbation can be detected in proxy evidence such as decrease in tree-ring widths and frost rings, changes in the treeline, weather anomalies, severity of sea-ice in polar and subpolar regions, and poor grain yields and crop failures. In low latitudes, sudden temperature drops were correlated with the passage overhead of the volcanic dust cloud (Stothers, 1984). For some eruptions, such as Tambora, 1815, these kinds of proxy and anectdotal information were summarized in great detail in a number of papers and books (e.g., Post, 1978; Stothers, 1984; Stommel and Stommel, 1986; C. R. Harrington, in press). These studies lead to the general conclusion that regional effects on climate, sometimes quite severe, may be the major impact of large historical volcanic aerosol clouds.

Spatial performance of RegEM climate field reconstruction techniques in a realistic pseudoproxy context

Science.gov (United States)

Wang, J.; Emile-Geay, J.; Guillot, D.

2011-12-01

Several methods of climate field reconstructions (CFRs) have been introduced in the past few years to estimate past climate variability from proxy data over the Common Era. The pseudoproxy framework has become a tool of choice for assessing the relative merits of such methods. Here we compare four variants of the RegEM algorithm [Schneider, 2001], using a pseudoproxy network mimicking the key spatio-temporal characteristics of the network of Mann et al., 2008 (hereinafter M08); the methods are (1) RegEM TTLS (2) RegEM iTTLS (3) GraphEM and (4) RegEM iRIDGE. To ensure continuity with previous work [Smerdon et al. 2011], pseudoproxy series are designed as a white-noise degraded version of the simulated temperature field [Amman et al. 2007] over 850-1980 C.E. colocated with 1138 M08 proxies. We use signal-to-noise ratios (SNRs) of: ∞ (no noise), 1.0, 0.5 and 0.25, to simulate differences in proxy quality. Two novelties in pseudoproxy design are introduced here: (1) the decrease in proxy availability over time follows that found in M08, (2) a realistic case where the SNR is empirically derived from correlations between each M08 proxy and the HadCRUT3v temperature field. It is found that this realistic SNR is clustered around 0.3, but ranges from 0.1 to 0.8. Verification statistics such as RE, CE, r2, bias, standard deviation ratio and RMSE are presented for each method at each SNR level. The results show that all methods perform relatively well at SNR levels higher than 0.5, but display drastically different performances at lower SNR levels. Compared with results using pseudoproxy network of Mann et al., 1998, (hereinafter MBH98), the reconstruction skill of the M08 network is relatively improved, in line with the findings of Smerdon et al., 2011. Overall, we find that GraphEM and iTTLS tend to produce more robust estimates of the temperature field at low SNR levels than other schemes, while preserving a higher amount of variance in the target field. Ammann, C. M., F

Holocene tree-line variability in the Kauner Valley, Central Eastern Alps, indicated by dendrochronological analysis of living trees and subfossil logs

NARCIS (Netherlands)

Nicolussi, Kurt; Kaufmann, Matthias; Patzelt, Gernot; van der Plicht, Johannes; Thurner, Andrea

2005-01-01

The altitude of the Alpine tree-line has often been used as proxy for the climatic conditions in the Holocene epoch. The usual approach for establishing a record for this proxy is the analysis of pollen and macro remains. We analysed living trees and subfossil logs from the timberline ecotone in the

Contracts, covenants and advance care planning: an empirical study of the moral obligations of patient and proxy.

Science.gov (United States)

Fins, Joseph J; Maltby, Barbara S; Friedmann, Erika; Greene, Michele G; Norris, Kaye; Adelman, Ronald; Byock, Ira

2005-01-01

Previously we had speculated that the patient-proxy relationship existed on a contractual to covenantal continuum. In order to assess this hypothesis, and to better understand the moral obligations of the patient-proxy relationship, we surveyed 50 patient-proxy pairs as well as 52 individuals who had acted as proxies for someone who had died. Using structured vignettes representative of three distinct disease trajectories (cancer, acute stroke, and congestive heart failure), we assessed whether respondents believed that proxies should follow explicit instructions regarding life-sustaining therapy and act contractually or whether more discretionary or covenantal judgments were ethically permissible. Additional variables included the valence of initial patient instructions--for example, "to do nothing" or "to do everything"--as well as the quality of information available to the proxy. Responses were graded on a contractual to covenantal continuum using a modified Likert scale employing a prospectively scored survey instrument. Our data indicate that the patient-proxy relationship exists on a contractual to covenantal continuum and that variables such as disease trajectory, the clarity of prognosis, instructional valence, and the quality of patient instructions result in statistically significant differences in response. The use of interpretative or covenantal judgment was desired by patients and proxies when the prognosis was grim, even if initial instructions were to pursue more aggressive care. Nonetheless, there was a valence effect: patients and proxies intended that negative instructions to be left alone be heeded. These data suggest that the delegation of patient self-determination is morally complex. Advance care planning should take into account both the exercise of autonomy and the interpretative burdens assumed by the proxy. Patients and proxies think inductively and contextually. Neither group viewed deviation from patient instructions as a violation of

Reliability of shell carbon isotope composition of different land snail species as a climate proxy: A case study in the monsoon region of China

Science.gov (United States)

Bao, Rui; Sheng, Xuefen; Teng, Henry H.; Ji, Junfeng

2018-05-01

Carbon isotope compositions of land snail shells (δ13Cshell) are shown to be indicative of local climate conditions. However, it is largely unknown how the responses of δ13Cshell to climatic factors changes amongst different species. In this study, we collected 3 species of land snail shells across the East Asian monsoon region of China to explore the overall relationship between δ13Cshell as well as the response of individual species to the regional climate. Results show that, whereas all species collectively can provide a consensus relation between δ13Cshell and local climatic factors such as temperature and precipitation; the response of individual species to the fluctuations of these factors is not uniform. Specifically, while the southerly species Bradybaena similaris exhibits robust δ13Cshell - mean precipitation correlation in both linearity and sensitivity, a common northerly species, Cathaica fasciola, only finds limited utility as a climate indicator, particularly for precipitation. Meanwhile, the south-central species Acusta ravida appears to be able to faithfully record past climate conditions despite showing a wider distribution and a broader habitat. Such species-dependent nature in the relations between δ13Cshell and local climatic factors can be attributed to the effect of ingested carbonate and variations in eco-physiological factors of different species, and is expected to be widespread, suggesting the need to be taken into consideration for future studies.

Climate Change Vulnerability and Resilience: Current Status and Trends for Mexico

Energy Technology Data Exchange (ETDEWEB)

Ibarraran , Maria E.; Malone, Elizabeth L.; Brenkert, Antoinette L.

2008-12-30

Climate change alters different localities on the planet in different ways. The impact on each region depends mainly on the degree of vulnerability that natural ecosystems and human-made infrastructure have to changes in climate and extreme meteorological events, as well as on the coping and adaptation capacity towards new environmental conditions. This study assesses the current resilience of Mexico and Mexican states to such changes, as well as how this resilience will look in the future. In recent studies (Moss et al. 2000, Brenkert and Malone 2005, Malone and Brenket 2008, Ibarrarán et al. 2007), the Vulnerability-Resilience Indicators Model (VRIM) is used to integrate a set of proxy variables that determine the resilience of a region to climate change. Resilience, or the ability of a region to respond to climate variations and natural events that result from climate change, is given by its adaptation and coping capacity and its sensitivity. On the one hand, the sensitivity of a region to climate change is assessed, emphasizing its infrastructure, food security, water resources, and the health of the population and regional ecosystems. On the other hand, coping and adaptation capacity is based on the availability of human resources, economic capacity and environmental capacity.

Light is an active contributor to the vital effects of coral skeleton proxies

Science.gov (United States)

Juillet-Leclerc, Anne; Reynaud, Stéphanie; Dissard, Delphine; Tisserand, Guillaume; Ferrier-Pagès, Christine

2014-09-01

assemblage of few corallites with their symbionts) presents its own vital effect influence over time. Therefore, at a bulk sample scale, light could be considered as one of the major causes of what is commonly referred to as the 'vital effect'. The meaning of δ18O calibration versus temperature established from distinct colonies differs from calibration calculated from samples collected following the growth axis of a single coral head. Finally, in order to quantitatively reconstruct climatic condition, we suggest a new paradigm based on the statistical treatment of the combination of time-series information from several proxies, all measured on the same sample from a continuous symbiosome.

Estimation of sedimentary proxy records together with associated uncertainty

OpenAIRE

Goswami, B.; Heitzig, J.; Rehfeld, K.; Marwan, N.; Anoop, A.; Prasad, S.; Kurths, J.

2014-01-01

Sedimentary proxy records constitute a significant portion of the recorded evidence that allows us to investigate paleoclimatic conditions and variability. However, uncertainties in the dating of proxy archives limit our ability to fix the timing of past events and interpret proxy record intercomparisons. While there are various age-modeling approaches to improve the estimation of the age–depth relations of archives, relatively little focus has been placed on the propagation...

SOILS AS INDICATORS OF CLIMATIC CHANGES

Directory of Open Access Journals (Sweden)

Yury Chendev

2012-01-01

Full Text Available A number of examples for the reaction of chernozems in the center of the East European Plain and their relation to different periodical climatic changes are examined. According to unequal-age chernozems properties, the transition from the Middle Holocene arid conditions to the Late Holocene wet conditions occurred at 4000 yr BP. Using data on changes of soil properties, the position of boundary between steppe and forest-steppe and the annual amount of precipitation at approximately 4000 yr BP were reconstructed. The change from warm-dry to cool-moist climatic phases, which occurred at the end of the XX century as a reflection of intra-age-long climatic cyclic recurrence, led to the strengthening of dehumification over the profile of automorphic chernozems and to the reduction of its content in the upper meter of the soils. The leaching of carbonates and of readily soluble salts contributed to the decrease in soil areas occupied by typical and solonetzic chernozems, and to the increase in areas occupied by leached chernozems.

Climate conditions in Sweden in a 100,000-year time perspective

Energy Technology Data Exchange (ETDEWEB)

Kjellstroem, Erik; Strandberg, Gustav (Rossby Centre, SMHI, Norrkoeping (Sweden)); Brandefelt, Jenny (Dept. of Mechanics, Royal Inst. of Technology, Stockholm (Sweden)); Naeslund, Jens-Ove (Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden)); Smith, Ben (Dept of Physical Geography and Ecosystems Analysis, Lund Univ., Lund (Sweden)); Wohlfarth, Barbara (Dept. of Geology and Geochemistry, Stockholm Univ., Stockholm (Sweden))

2009-04-15

some additional sensitivity studies, and also compare our scenarios to other existing model scenarios when possible. In addition to the modelling activities, an effort has been made to collect palaeoclimatic information by compiling various MIS 3 and LGM proxy data from different sources. An attempt to use part of this palaeoclimatic information to constrain the forcing conditions used in the climate models has been made. Other proxy data were used for model evaluation purposes. We have compared results from the global climate model with proxy records of sea-surface temperatures and with terrestrial records. The regional climate model results have been compared with existing terrestrial palaeoclimate records from Europe. The results show that the climate models produce climates for the three periods that are in broad agreement with proxy data and other climate model simulations. The resulting climates are also in qualitative agreement with the imposed extent of ice sheets and types of vegetation. In particular, we show that the results for the MIS 3 stadial are consistent with ice-free conditions in south-central Fennoscandia and that this climate is suitable for permafrost growth. The simulations show that there is a large range in possible climates for the Fennoscandian region in a 100,000 year time perspective. Excluding the glacial situation, annual mean temperatures for the Forsmark, Oskarshamn and Olkiluoto sites differ from MIS 3 to the future warm climate by 12-15 deg C. Correspondingly, annual mean precipitation is almost a factor two higher in the future warm climate compared to MIS 3 at these sites. This report documents forcing conditions and model results, both from the global and regional climate models as well as from the vegetation model. Results from the project in the form of modelled climate and vegetation data for different climatic extremes are available for further impact studies in other projects

Climate conditions in Sweden in a 100,000-year time perspective

International Nuclear Information System (INIS)

Kjellstroem, Erik; Strandberg, Gustav; Brandefelt, Jenny; Naeslund, Jens-Ove; Smith, Ben; Wohlfarth, Barbara

2009-04-01

some additional sensitivity studies, and also compare our scenarios to other existing model scenarios when possible. In addition to the modelling activities, an effort has been made to collect palaeoclimatic information by compiling various MIS 3 and LGM proxy data from different sources. An attempt to use part of this palaeoclimatic information to constrain the forcing conditions used in the climate models has been made. Other proxy data were used for model evaluation purposes. We have compared results from the global climate model with proxy records of sea-surface temperatures and with terrestrial records. The regional climate model results have been compared with existing terrestrial palaeoclimate records from Europe. The results show that the climate models produce climates for the three periods that are in broad agreement with proxy data and other climate model simulations. The resulting climates are also in qualitative agreement with the imposed extent of ice sheets and types of vegetation. In particular, we show that the results for the MIS 3 stadial are consistent with ice-free conditions in south-central Fennoscandia and that this climate is suitable for permafrost growth. The simulations show that there is a large range in possible climates for the Fennoscandian region in a 100,000 year time perspective. Excluding the glacial situation, annual mean temperatures for the Forsmark, Oskarshamn and Olkiluoto sites differ from MIS 3 to the future warm climate by 12-15 deg C. Correspondingly, annual mean precipitation is almost a factor two higher in the future warm climate compared to MIS 3 at these sites. This report documents forcing conditions and model results, both from the global and regional climate models as well as from the vegetation model. Results from the project in the form of modelled climate and vegetation data for different climatic extremes are available for further impact studies in other projects

Penguin tissue as a proxy for relative krill abundance in East Antarctica during the Holocene.

Science.gov (United States)

Huang, Tao; Sun, Liguang; Long, Nanye; Wang, Yuhong; Huang, Wen

2013-09-30

Antarctic krill (Euphausia superba) is a key component of the Southern Ocean food web. It supports a large number of upper trophic-level predators, and is also a major fishery resource. Understanding changes in krill abundance has long been a priority for research and conservation in the Southern Ocean. In this study, we performed stable isotope analyses on ancient Adélie penguin tissues and inferred relative krill abundance during the Holocene epoch from paleodiets of Adélie penguin (Pygoscelis adeliae), using inverse of δ¹⁵N (ratio of ¹⁵N/¹⁴N) value as a proxy. We find that variations in krill abundance during the Holocene are in accord with episodes of regional climate changes, showing greater krill abundance in cold periods. Moreover, the low δ¹⁵N values found in modern Adélie penguins indicate relatively high krill availability, which supports the hypothesis of krill surplus in modern ages due to recent hunt for krill-eating seals and whales by humans.

Analisis Algoritma Pergantian Cache Pada Proxy Web Server Internet Dengan Simulasi

OpenAIRE

Nurwarsito, Heru

2007-01-01

Pertumbuhan jumlah client internet dari waktu ke waktu terus bertambah, maka respon akses internet menjadi semakin lambat. Untuk membantu kecepatan akses tersebut maka diperlukan cache pada Proxy Server. Penelitian ini bertujuan untuk menganalisis performansi Proxy Server pada Jaringan Internet terhadap penggunaan algoritma pergantian cache-nya.Analisis Algoritma Pergantian Cache Pada Proxy Server didesain dengan metoda pemodelan simulasi jaringan internet yang terdiri dari Web server, Proxy ...

Gradient-based model calibration with proxy-model assistance

Science.gov (United States)

Burrows, Wesley; Doherty, John

2016-02-01

Use of a proxy model in gradient-based calibration and uncertainty analysis of a complex groundwater model with large run times and problematic numerical behaviour is described. The methodology is general, and can be used with models of all types. The proxy model is based on a series of analytical functions that link all model outputs used in the calibration process to all parameters requiring estimation. In enforcing history-matching constraints during the calibration and post-calibration uncertainty analysis processes, the proxy model is run for the purposes of populating the Jacobian matrix, while the original model is run when testing parameter upgrades; the latter process is readily parallelized. Use of a proxy model in this fashion dramatically reduces the computational burden of complex model calibration and uncertainty analysis. At the same time, the effect of model numerical misbehaviour on calculation of local gradients is mitigated, this allowing access to the benefits of gradient-based analysis where lack of integrity in finite-difference derivatives calculation would otherwise have impeded such access. Construction of a proxy model, and its subsequent use in calibration of a complex model, and in analysing the uncertainties of predictions made by that model, is implemented in the PEST suite.

Testing the Value of Information of Climate Change Indicators that use Earth Observations

Science.gov (United States)

Kenney, M. A.

2012-12-01

Indicators are usually thought of as measurements or calculations that represent important features of the status, trend, or performance of a system of interest (e.g. the economy, agriculture, air quality). They are often used for the most practical of reasons - one cannot measure everything important about systems of interest, so there is a practical need to identify major features that can be reported periodically and used to guide both research and decisions (National Research Council (NRC). 2000. Ecological Indicators for the Nation. National Academy Press. Washington, DC). The use of indicators to track the status and trends of many features of environmental or economic performance, quality of life, and a host of other social concerns is embedded in the fabric of our everyday lives. Businesses, governments, and consumers regularly use the common economic indices - e.g. the unemployment index or consumer price index - as guides for decision-making on investments and hiring. There is an analogous demand for indicators of environmental conditions and performance - everything from agricultural yields to air and water quality to weather and climate - that are currently less publicly visible than the common economic indicators, but that can have critically important uses in such areas as natural resource management, improvement of environmental quality, emergency planning, and infrastructure development. A number of these environmental indicators, be it physical or ecological, use a range of data sources including earth observations. Despite the extensive development and use of indicators, there is little testing of these indicators to assure that they indeed provide the assumed positive information benefit. This is particularly concerning because if these indicators are systematically misunderstood by the intended audience or a sub-group of that audience, such individuals could make decisions that are consistent with their incorrect understanding of the indicator

North Atlantic-Fennoscandian Holocene climate trends and mechanisms

NARCIS (Netherlands)

Sejrup, H.P.; Seppä, H.; McKay, N.; Kaufman, D.S.; Geirsdottir, A.; de Vernal, A.; Renssen, H.; Husum, K.; Jennings, A.; Andrews, J.T.

2016-01-01

To investigate the mechanisms behind Holocene regional climate trends from north of 58°N in the North Atlantic-Fennoscandian region Principal Component Analysis (PCA) was performed and a temperature anomaly stack produced from 81 proxy derived summer temperature time series from 74 sites. The PC

Indicators of climate change in Idaho: An assessment framework for coupling biophysical change and social perception

Science.gov (United States)

Climate change is well documented at the global scale, but local and regional changes are not as well understood. Finer, local-to-regional scale information is needed for creating specific, place-based planning and adaption efforts. Here we detail the development of an indicator-focused climate chan...

RESPONSE OF THREE PALEO-PRIMARY PRODUCTION PROXY MEASURES TO DEVELOPMENT OF AN URBAN ESTUARY

Science.gov (United States)

In this study we present a novel comparison of three proxy indicators of paleoproductivity, pigments, biogenic silica (BSi), and cysts of autotrophic dinoflagellates measured in cored sediments from New Bedford Harbor, Massachusetts. In addition to detailed historical reports we ...

Modeling Climate and Societal Resilience in the Mediterranean During the Last Millennium

Science.gov (United States)

Wagner, S.; Xoplaki, E.; Luterbacher, J.; Zorita, E.; Fleitmann, D.; Preiser-Kapeller, J.; Toreti, A., , Dr; Sargent, A. M.; Bozkurt, D.; White, S.; Haldon, J. F.; Akçer-Ön, S.; Izdebski, A.

2017-12-01

Past civilisations were influenced by complex external and internal forces, including changes in the environment, climate, politics and economy. A geographical hotspot of the interplay between those agents is the Mediterranean, a cradle of cultural and scientific development. We analyse a novel compilation of high-quality hydroclimate proxy records and spatial reconstructions from the Mediterranean and compare them with two Earth System Model simulations (CCSM4, MPI-ESM-P) for three historical time intervals - the Crusaders, 1095-1290 CE; the Mamluk regime in Transjordan, 1260-1516 CE; and the Ottoman crisis and Celâlî Rebellion, 1580-1610 CE - when environmental and climatic stress tested the resilience of complex societies. ESMs provide important information on the dynamical mechanisms and underlying processes that led to anomalous hydroclimatic conditions of the past. We find that the multidecadal precipitation and drought variations in the Central and Eastern Mediterranean during the three periods cannot be explained by external forcings (solar variations, tropical volcanism); rather they were driven by internal climate dynamics. The integrated analysis of palaeoclimate proxies, climate reconstructions and model simulations sheds light on our understanding of past climate change and its societal impact. Finally, our research emphasises the need to further study the societal dimension of environmental and climate change in the past, in order to properly understand the role that climate has played in human history.

Bringing indices of species vulnerability to climate change into geographic space: an assessment across the Coronado national forest

Science.gov (United States)

Jennifer E. Davison; Sharon Coe; Deborah Finch; Erika Rowland; Megan Friggens; Lisa J. Graumlich

2012-01-01

Indices that rate the vulnerability of species to climate change in a given area are increasingly used to inform conservation and climate change adaptation strategies. These species vulnerability indices (SVI) are not commonly associated with landscape features that may affect local-scale vulnerability. To do so would increase their utility by allowing managers to...

Mid-Pliocene to Early Pleistocene land and sea surface temperature history of NW Australia based on organic geochemical proxies

Science.gov (United States)

Smith, R. A.; Castañeda, I. S.; Henderiks, J.; Christensen, B. A.; De Vleeschouwer, D.; Renema, W.; Groeneveld, J.; Bogus, K.; Gallagher, S. J.; Fulthorpe, C.; Expedition 356 Scientists, I.

2017-12-01

IODP Expedition 356 Site U1463 is located off the coast of NW Australia, and is sensitive to Indonesian Throughflow (ITF) variability. The ITF is a critical ocean gateway that affects global thermohaline circulation, and regulates the movement of water from the Pacific Ocean into the Indian Ocean. However, despite its importance to the global climate system, few SST reconstructions exist for this region that span the Plio-Pleistocene. Here we investigate both the land and sea-surface temperature (SST) history of NW Australia to constrain ITF variability across the Plio-Pleistocene interval. We apply multiple organic geochemical proxies to this site from 3.4-2.6 Ma, which includes the mid-Pliocene warm period, characterized by slightly higher (2-3°C) global temperatures and similar CO2 concentrations to modern values (e.g. Badger et al. 2013; Bartoli et al., 2011; Dowsett et al., 2009; Hönisch et al., 2009; Pagani et al. 2009; Raymo et al., 1996). SST was reconstructed using TEX86, based on isoprenoid glycerol dialkyl glycerol tetraethers (iGDGTs), and the long-chain diol index (LDI), based on the ratio of diols produced by marine diatoms (Rampen et al., 2012). The Uk'37 index, based on long-chain ketones, was analyzed but cannot be applied as a SST proxy at this site due to the influence of coastal alkenone producers. Additionally, a continental air temperature record was developed using the MBT'5ME proxy, based on branched GDGTs (De Jonge et al., 2014; Weijers et al., 2007). We find that TEX86, LDI and MBT'5Me exhibit similar trends and show relatively warm and stable temperatures from 3.5-2.4 Ma followed by a gradual cooling of 3-4°C from 2.4-1.5 Ma. This cooling corresponds with an arid interval previously identified on the same core by Christensen et al. (2017). Furthermore, we find that the TEX86 record agrees closely with the LR04 global benthic δ18O stack (Lisiecki and Raymo, 2005) and captures glacial/interglacial periods including Marine Isotope Stage

Nitrogen isotopes from terrestrial organic matter as a new paleoclimatic proxy for pre-quaternary time

Science.gov (United States)

Tramoy, romain; Schnyder, johann; thuy Nguyen Tu, thanh; Yans, johan; Storme, jean yves; Sebilo, mathieu; Derenne, sylvie; Jacob, jérémy; Baudin, françois

2014-05-01

Taskomirsay, Kazakhstan. This succession is rich in dispersed OM and wood fragments allowing accurate N isotopes measurements. Preliminary results on δ13Corg and palynology suggest that the Pliensbachian/Toarcian transition is recorded at the top of the sedimentary succession. This transition has been studied for a long time since it is characterized by one of the most important global environmental and climatic change of the Phanerozoic time ( Jenkyns, 1988; Hermoso et al., 2012). We are therefore testing the paleoclimatic "proxy" potential of δ15Norg for this time interval by comparing the δ15Norg signal with other indicators more classically used for paleoclimate studies. We have also investigated the influence of differences in organic sources and of early diagenesis on the δ15Norg variations.

Sphagnum-dwelling testate amoebae in subarctic bogs are more sensitive to soil warming in the growing season than in winter: the results of eight-year field climate manipulations.

Science.gov (United States)

Tsyganov, Andrey N; Aerts, Rien; Nijs, Ivan; Cornelissen, Johannes H C; Beyens, Louis

2012-05-01

Sphagnum-dwelling testate amoebae are widely used in paleoclimate reconstructions as a proxy for climate-induced changes in bogs. However, the sensitivity of proxies to seasonal climate components is an important issue when interpreting proxy records. Here, we studied the effects of summer warming, winter snow addition solely and winter snow addition together with spring warming on testate amoeba assemblages after eight years of experimental field climate manipulations. All manipulations were accomplished using open top chambers in a dry blanket bog located in the sub-Arctic (Abisko, Sweden). We estimated sensitivity of abundance, diversity and assemblage structure of living and empty shell assemblages of testate amoebae in the living and decaying layers of Sphagnum. Our results show that, in a sub-arctic climate, testate amoebae are more sensitive to climate changes in the growing season than in winter. Summer warming reduced species richness and shifted assemblage composition towards predominance of xerophilous species for the living and empty shell assemblages in both layers. The higher soil temperatures during the growing season also decreased abundance of empty shells in both layers hinting at a possible increase in their decomposition rates. Thus, although possible effects of climate changes on preservation of empty shells should always be taken into account, species diversity and structure of testate amoeba assemblages in dry subarctic bogs are sensitive proxies for climatic changes during the growing season. Copyright © 2011 Elsevier GmbH. All rights reserved.

The last millennium of Aleutian low variability based on dendrochonolgy and water isotope proxies

Science.gov (United States)

Gaglioti, B.; Mann, D. H.; Andreu-Hayles, L.; Wiles, G. C.; Streverler, G.; Williams, P.; Field, R. D.; D'Arrigo, R.

2017-12-01

How the wintertime Aleutian Low pressure system (AL) will respond to climate forcing is germane to the forest resources, glaciers, and fisheries in the North Pacific region. Recent work suggests the AL has strengthened over the last few centuries, and new, high-resolution paleo-records could help evaluate this trend. Namely, when it started, whether it has any historical precedents, and what it means for high-latitude climate feedbacks? Our study area is Southeast Alaska and the Southwest Yukon Territory, where the winters are warmer and wetter when the AL is stronger (deeper) and positioned further east. First, we use newly developed winter-sensitive tree-ring records to determine how AL variability has changed over the past 1000 years. During winters with a stronger AL, meridional flow brings: (i) heavy ice storms and snow loads to the coastal mountains that can injure sub-alpine trees; (ii) thaw events that can compromise growth in coastal forests; and (iii) changes in seasonality that can moderate the climate sensitivity of mid-elevation trees. Therefore, a time series of changing tree architecture in the mountains, tree ring widths in the lowlands, and running inter-series correlation in mid-slope chronologies collectively provide a landscape-level view of paleo-AL variability. Second, we compare and complement this dendro perspective with new proxy records based on stable oxygen isotope ratios measured in tree-ring and peat cellulose (d18O cell). To interpret how these proxies reflect the AL, we analyze the precipitation isotopes in Gustavus, Alaska over the past 16 months. We then use d18Ocell time series along a coastal to inland transect that records the degree of heavy-isotope rainout over the St. Elias Mountains, a factor that depends on the sources and pathways of the dominant storm tracks, which are influenced by the AL strength. We will present these new data in the context of existing AL reconstructions, and discuss the implications for the ongoing

Limitations of climatic data for inferring species boundaries: insights from speckled rattlesnakes.

Directory of Open Access Journals (Sweden)

Jesse M Meik

Full Text Available Phenotypes, DNA, and measures of ecological differences are widely used in species delimitation. Although rarely defined in such studies, ecological divergence is almost always approximated using multivariate climatic data associated with sets of specimens (i.e., the "climatic niche"; the justification for this approach is that species-specific climatic envelopes act as surrogates for physiological tolerances. Using identical statistical procedures, we evaluated the usefulness and validity of the climate-as-proxy assumption by comparing performance of genetic (nDNA SNPs and mitochondrial DNA, phenotypic, and climatic data for objective species delimitation in the speckled rattlesnake (Crotalus mitchellii complex. Ordination and clustering patterns were largely congruent among intrinsic (heritable traits (nDNA, mtDNA, phenotype, and discordance is explained by biological processes (e.g., ontogeny, hybridization. In contrast, climatic data did not produce biologically meaningful clusters that were congruent with any intrinsic dataset, but rather corresponded to regional differences in atmospheric circulation and climate, indicating an absence of inherent taxonomic signal in these data. Surrogating climate for physiological tolerances adds artificial weight to evidence of species boundaries, as these data are irrelevant for that purpose. Based on the evidence from congruent clustering of intrinsic datasets, we recommend that three subspecies of C. mitchellii be recognized as species: C. angelensis, C. mitchellii, and C. Pyrrhus.

Taraxerol and Rhizophora pollen as proxies for tracking past mangrove ecosystems 1

Science.gov (United States)

Versteegh, Gerard J. M.; Schefuß, Enno; Dupont, Lydie; Marret, Fabienne; Sinninghe Damsté, Jaap S.; Jansen, J. H. Fred

2004-02-01

Angola Basin and Cape Basin (southeast Atlantic) surface sediments and sediment cores show that maxima in the abundance of taraxerol (relative to other land-derived lipids) covary with maxima in the relative abundance of pollen from the mangrove tree genus Rhizophora and that in the surface sediments offshore maxima in the relative abundance of taraxerol occur at latitudes with abundant coastal mangrove forests. Together with the observation that Rhizophora mangle and Rhizophora racemosa leaves are extraordinarily rich in taraxerol, this strongly indicates that taraxerol can be used as a lipid biomarker for mangrove input to the SE Atlantic. The proxy-environment relations for taraxerol and Rhizophora pollen down-core show that increased taraxerol and Rhizophora pollen abundances occur during transgressions and periods with a humid climate. These environmental changes modify the coastal erosion and sedimentation patterns, enhancing the extent of the mangrove ecosystem and/or the transport of mangrove organic matter offshore. Analyses of mid-Pleistocene sediments show that interruption of the pattern of taraxerol maxima during precession minima occurs almost only during periods of low obliquity. This demonstrates the complex environmental response of the interaction between precession-related humidity cycles and obliquity-related sea-level changes on mangrove input.

A multi-proxy geochemical investigation of late-Quaternary paleoenvironmental change from Burial Lake, Noatak National Preserve, Alaska

Science.gov (United States)

Finkenbinder, M. S.; Abbott, M.; Stoner, J. S.; Dorfman, J. M.

2012-12-01

Here we present a new multi-proxy geochemical analysis of paleoenvironmental change inferred from sediment cores recovered from Burial Lake (68.434° N, 159.174° W; 430 m ASL) in northwest Alaska. Previous work on cores from 7.9 m water depth sampled at comparatively low resolution revealed basal sediments date to ~ 40,000 cal yr BP and an unconformity during a period of aridity around the Last Glacial Maximum (LGM). We therefore collected multiple overlapping Livingston cores from the lake depocenter (21.5 m water depth) in the summer of 2010 in an effort to develop a temporally continuous, high resolution record spanning prior to the LGM to the present. We focus our interpretations on a 6.51 m core developed through wiggle matching proxy data from core sites A10 and C10. We use traditional laboratory methods and investigate new approaches to assess changes in sedimentation and productivity. We are measuring dry bulk density, organic matter via Loss-on-ignition at 550° C, biogenic silica, magnetic susceptibility, grain size via laser diffractometry, and elemental abundances via scanning x-ray fluorescence (XRF). Future research seeks to test the reliability of two commonly used XRF proxies, for organic matter (incoherence/coherence ratios) and aquatic productivity (Si/Ti ratios). Age control is provided by 12 Accelerator Mass Spectrometry radiocarbon dates of discrete terrestrial macrofossils. Results from these analyses indicate that the depocenter core is continuous and the sediment record spans the last ~ 38,000 cal yr BP and most importantly contains sediments spanning the LGM. Preliminary geochemical results demonstrate substantial cyclicity in organic matter and aquatic productivity beginning in the late-glacial. We seek to analyze the periodicity of these proxies through spectral analysis, although initial observations suggest multi-century to millennial scale variability. In addition, we note the presence of two abrupt, non-linear transitions in organic

A multi-proxy record of hydroclimate, vegetation, fire, and post-settlement impacts for a subalpine plateau, Central Rocky Mountains U.S.A

Science.gov (United States)

Anderson, Lesleigh; Brunelle, Andrea; Thompson, Robert S.

2015-01-01

Apparent changes in vegetation distribution, fire, and other disturbance regimes throughout western North America have prompted investigations of the relative importance of human activities and climate change as potential causal mechanisms. Assessing the effects of Euro-American settlement is difficult because climate changes occur on multi-decadal to centennial time scales and require longer time perspectives than historic observations can provide. Here, we report vegetation and environmental changes over the past ~13,000 years as recorded in a sediment record from Bison Lake, a subalpine lake on a high plateau in northwestern Colorado. Results are based on multiple independent proxies, which include pollen, charcoal, and elemental geochemistry, and are compared with previously reported interpretations of hydroclimatic changes from oxygen isotope ratios. The pollen data indicate a slowly changing vegetation sequence from sagebrush steppe during the late glacial to coniferous forest through the late Holocene. The most dramatic vegetation changes of the Holocene occurred during the ‘Medieval Climate Anomaly’ (MCA) and ‘Little Ice Age’ (LIA) with rapid replacement of conifer forest by grassland followed by an equally rapid return to conifer forest. Late Holocene vegetation responses are mirrored by changes in fire, lake biological productivity, and watershed erosion. These combined records indicate that subsequent disturbance related to Euro-American settlement, although perhaps significant, had acted upon a landscape that was already responding to MCA-LIA hydroclimatic change. Results document both rapid and long-term subalpine grassland ecosystem dynamics driven by agents of change that can be anticipated in the future and simulated by ecosystem models.

The Early Eocene equable climate problem: can perturbations of climate model parameters identify possible solutions?

Science.gov (United States)

Sagoo, Navjit; Valdes, Paul; Flecker, Rachel; Gregoire, Lauren J

2013-10-28

Geological data for the Early Eocene (56-47.8 Ma) indicate extensive global warming, with very warm temperatures at both poles. However, despite numerous attempts to simulate this warmth, there are remarkable data-model differences in the prediction of these polar surface temperatures, resulting in the so-called 'equable climate problem'. In this paper, for the first time an ensemble with a perturbed climate-sensitive model parameters approach has been applied to modelling the Early Eocene climate. We performed more than 100 simulations with perturbed physics parameters, and identified two simulations that have an optimal fit with the proxy data. We have simulated the warmth of the Early Eocene at 560 ppmv CO2, which is a much lower CO2 level than many other models. We investigate the changes in atmospheric circulation, cloud properties and ocean circulation that are common to these simulations and how they differ from the remaining simulations in order to understand what mechanisms contribute to the polar warming. The parameter set from one of the optimal Early Eocene simulations also produces a favourable fit for the last glacial maximum boundary climate and outperforms the control parameter set for the present day. Although this does not 'prove' that this model is correct, it is very encouraging that there is a parameter set that creates a climate model able to simulate well very different palaeoclimates and the present-day climate. Interestingly, to achieve the great warmth of the Early Eocene this version of the model does not have a strong future climate change Charney climate sensitivity. It produces a Charney climate sensitivity of 2.7(°)C, whereas the mean value of the 18 models in the IPCC Fourth Assessment Report (AR4) is 3.26(°)C±0.69(°)C. Thus, this value is within the range and below the mean of the models included in the AR4.

Developing a reduced-form ensemble of climate change scenarios for Europe and its application to selected impact indicators

Czech Academy of Sciences Publication Activity Database

Dubrovský, Martin; Trnka, M.; Holman, I. P.; Svobodová, E.; Harrison, P. A.

2015-01-01

Roč. 128, 3-4 (2015), s. 169-186 ISSN 0165-0009 R&D Projects: GA MŠk LD12029 Institutional support: RVO:68378289 Keywords : global Climate Model * ensemble of models * climate change * climate change scenarios * climate change impact indices * Europe Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 3.344, year: 2015 http://link.springer.com/article/10.1007%2Fs10584-014-1297-7

Using climate information for improved health in Africa: relevance, constraints and opportunities

Directory of Open Access Journals (Sweden)

Stephen J. Connor

2006-11-01

Full Text Available Good health status is one of the primary aspirations of human social development and, as a consequence, health indicators are key components of the human development indices by which we measure progress toward sustainable development. Certain diseases and ill health are associated with particular environmental and climate conditions. The timeframe of the Millennium Development Goals (MDGs demands that the risks to health associated with current climate variability are more fully understood and acted upon to improve the focus of resources in climate sensitive disease control, especially in sub-Saharan Africa, where good epidemiological surveillance data are lacking. In the absence of high-quality epidemiological data on malaria distribution in Africa, climate information has long been used to develop malaria risk maps illustrating the climatic suitability boundaries for endemic transmission. However, experience to date has shown that it is difficult in terms of availability, timing and cost to obtain meteorological observations from national meteorological services in Africa. National health services generally find the costs of purchasing these data prohibitive given their competing demands for resources across the spectrum of health service requirements. Some national health services have tried to overcome this access problem by using proxies derived from satellites, which tend to be available freely, in 'near-real-time' and therefore offer much promise for monitoring applications. This paper discusses the issues related to climate and health, reviews the current use of climate information for malaria endemic and epidemic surveillance, and presents examples of operational use of climate information for malaria control in Africa based on Geographical Information Systems and Remote Sensing.

Munchausen by Proxy Syndrome

Science.gov (United States)

... the Child Getting Help for the Parent or Caregiver Print Munchausen by proxy syndrome (MBPS) is a relatively rare form of child abuse that involves the exaggeration or fabrication of illnesses or symptoms by a primary caretaker. Also known as "medical child abuse," MBPS ...

Holocene record of glacier variability from lake sediments reveals tripartite climate history for Svalbard

Science.gov (United States)

van der Bilt, Willem; Bakke, Jostein; Vasskog, Kristian; D`Andrea, William; Bradley, Raymond; Olafsdottir, Sædis

2016-04-01

The Arctic is responding sensitively to ongoing global climate change, warming and moistening faster than any other region on the planet. Holocene proxy paleoclimate time series are increasingly used to put this amplified response in perspective by understanding Arctic climate processes beyond the instrumental period. Glaciers rapidly respond to climate shifts as demonstrated by their current demise around the world. This response has a composite climate signature, marked by shifts in hydroclimate (winter precipitation) as well as (summer) temperature. Attendant changes in glacier size are recorded by variations in glacigenic rock flour that may be deposited in downstream lakes. Here, we present a Holocene reconstruction of glacier activity, based on sediments from Hajeren, a glacier-fed lake on northwest Spitsbergen in the High Arctic Svalbard archipelago. Owing to undisturbed sediments and robust age control, we could resolve variability on a sub-centennial scale. To ensure the accurate detection of glacier activity, we applied a toolbox of physical, magnetic and geochemical proxies in conjunction with multivariate statistics. Our findings indicate a three-stage Holocene climate history for Svalbard, driving by melt water pulses, episodic Atlantic cooling and a decline in orbitally driven summer insolation. Correspondence between inferred advances, including a Holocene glacier maximum around 9.5 ka BP, suggests forcing by the melting LIS during the Early Holocene. Following a late Holocene Thermal Maximum around 7.4 ka BP, glaciers disappeared from the catchment. Glaciers reformed around 4.2 ka BP during the regional onset of the Neoglacial, supporting previous findings. This transition did, however, not mark the onset of persistent glacier activity in the catchment, but a series of centennial-scale cycles of growth and decay, including events around 3.3 and 1.1 ka BP. As orbitally driven insolation declined towards the present, the glaciation threshold

Reliability and validity of a self-administration version of DEMQOL-Proxy.

Science.gov (United States)

Hendriks, A A Jolijn; Smith, Sarah C; Chrysanthaki, Theopisti; Black, Nick

2017-07-01

This study aimed to investigate the reliability and validity of a self-administered version of DEMQOL-Proxy, a disease-specific instrument that measures health-related quality of life in people with dementia. The sample consisted of 173 informal carers of people with dementia, aged 29 to 89 years old. Carers were mostly female, White/White British and closely related to the patient. They completed DEMQOL-Proxy (self-administered), EQ-5D-3L (proxy reported about the person with dementia), EQ-5D-3L (self-reported about their own health) and the Zarit Burden Interview. Using well-established methods from classical test theory, we evaluated scale level acceptability, reliability and convergent, discriminant and known-groups validity of DEMQOL-Proxy. DEMQOL-Proxy (self-administered) showed high acceptability (3.5% missing data and 0% scores at floor or ceiling), high internal consistency reliability (α = 0.93) and good convergent and discriminant validity. Amongst others, we found a moderately high correlation with EQ-5D-3L proxy reported (r = 0.52) and low to essentially zero correlations with EQ-5D-3L self-reported (r = 0.20) and carer and patient background variables (r ≤ 0.20). As predicted, DEMQOL-Proxy (self-administered) showed a modest correlation with DEMQOL (r = 0.32). Known-groups differences on health-related quality of life (comparing people with versus people without cognitive impairment) were of moderate effect size (d = 0.38) and in the expected direction. DEMQOL-Proxy (self-administered) has comparable acceptability, reliability and validity with DEMQOL-Proxy (interviewer administered). DEMQOL-Proxy (self-administered) can be used in a wider variety of contexts than its interviewer-administered version, including routine use in busy clinics. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

On the construction of a time base and the elimination of averaging errors in proxy records

Science.gov (United States)

Beelaerts, V.; De Ridder, F.; Bauwens, M.; Schmitz, N.; Pintelon, R.

2009-04-01

Proxies are sources of climate information which are stored in natural archives (e.g. ice-cores, sediment layers on ocean floors and animals with calcareous marine skeletons). Measuring these proxies produces very short records and mostly involves sampling solid substrates, which is subject to the following two problems: Problem 1: Natural archives are equidistantly sampled at a distance grid along their accretion axis. Starting from these distance series, a time series needs to be constructed, as comparison of different data records is only meaningful on a time grid. The time series will be non-equidistant, as the accretion rate is non-constant. Problem 2: A typical example of sampling solid substrates is drilling. Because of the dimensions of the drill, the holes drilled will not be infinitesimally small. Consequently, samples are not taken at a point in distance, but rather over a volume in distance. This holds for most sampling methods in solid substrates. As a consequence, when the continuous proxy signal is sampled, it will be averaged over the volume of the sample, resulting in an underestimation of the amplitude. Whether this averaging effect is significant, depends on the volume of the sample and the variations of interest of the proxy signal. Starting from the measured signal, the continuous signal needs to be reconstructed in order eliminate these averaging errors. The aim is to provide an efficient identification algorithm to identify the non-linearities in the distance-time relationship, called time base distortions, and to correct for the averaging effects. Because this is a parametric method, an assumption about the proxy signal needs to be made: the proxy record on a time base is assumed to be harmonic, this is an obvious assumption because natural archives often exhibit a seasonal cycle. In a first approach the averaging effects are assumed to be in one direction only, i.e. the direction of the axis on which the measurements were performed. The

Assessing debris flow activity in a changing climate : open access

NARCIS (Netherlands)

Turkington, T.; Remaitre, A.; Ettema, J.; Hussin, H.Y.; van Westen, C.J.

2016-01-01

Future trends in debris flow activity are constructed based on bias-corrected climate change projections using two meteorological proxies: daily precipitation and Convective Available Potential Energy (CAPE) combined with specific humidity for two Alpine areas. Along with a comparison between

Arctic and Antarctic Oscillation signatures in tropical coral proxies over the South China Sea

Directory of Open Access Journals (Sweden)

D.-Y. Gong

2009-05-01

Full Text Available Arctic Oscillation (AO and Antarctic Oscillation (AAO are the leading modes of atmospheric circulation in mid-high latitudes. Previous studies have revealed that the climatic influences of the two modes are dominant in extra-tropical regions. This study finds that AO and AAO signals are also well recorded in coral proxies in the tropical South China Sea. There are significant interannual signals of AO and AAO in the strontium (Sr content, which represents the sea surface temperature (SST. Among all the seasons, the most significant correlation occurs during winter in both hemispheres: the strongest AO-Sr and AAO-Sr coral correlations occur in January and August, respectively. This study also determined that the Sr content lags behind AO and AAO by 1–3 months. Large-scale anomalies in sea level pressure and horizontal wind at 850 hPa level support the strength of AO/AAO-coral teleconnections. In addition, a comparison with oxygen isotope records from two coral sites in neighboring oceans yields significant AO and AAO signatures with similar time lags. These results help to better understand monsoon climates and their teleconnection to high-latitude climate changes.

Climatic and environmental events over the Last Termination, as recorded in The Netherlands: a review

NARCIS (Netherlands)

Hoek, W.Z.; Bohncke, S.J.P.

The Last Termination, or Weichselian Lateglacial (ca 15-10 ka cal. BP), is a time period with rapid changes in climate and environment. The oxygen-isotope records of the Greenland ice-cores are regarded as the most complete climate proxy for the North Atlantic region. In The Netherlands several

Predicting shifting sustainability tradeoffs in marine finfish aquaculture under climate change.

Science.gov (United States)

Sarà, Gianluca; Gouhier, Tarik C; Brigolin, Daniele; Porporato, Erika M D; Mangano, M Cristina; Mirto, Simone; Mazzola, Antonio; Pastres, Roberto

2018-05-03

Defining sustainability goals is a crucial but difficult task because it often involves the quantification of multiple interrelated and sometimes conflicting components. This complexity may be exacerbated by climate change, which will increase environmental vulnerability in aquaculture and potentially compromise the ability to meet the needs of a growing human population. Here, we developed an approach to inform sustainable aquaculture by quantifying spatio-temporal shifts in critical trade-offs between environmental costs and benefits using the time to reach the commercial size as a possible proxy of economic implications of aquaculture under climate change. Our results indicate that optimizing aquaculture practices by minimizing impact (this study considers as impact a benthic carbon deposition ≥ 1 gC m -2 d -1 ) will become increasingly difficult under climate change. Moreover, an increasing temperature will produce a poleward shift in sustainability trade-offs. These findings suggest that future sustainable management strategies and plans will need to account for the effects of climate change across scales. Overall, our results highlight the importance of integrating environmental factors in order to sustainably manage critical natural resources under shifting climatic conditions. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Sensitivity of the Palaeocene-Eocene Thermal Maximum climate to cloud properties.

Science.gov (United States)

Kiehl, Jeffrey T; Shields, Christine A

2013-10-28

The Palaeocene-Eocene Thermal Maximum (PETM) was a significant global warming event in the Earth's history (approx. 55 Ma). The cause for this warming event has been linked to increases in greenhouse gases, specifically carbon dioxide and methane. This rapid warming took place in the presence of the existing Early Eocene warm climate. Given that projected business-as-usual levels of atmospheric carbon dioxide reach concentrations of 800-1100 ppmv by 2100, it is of interest to study past climates where atmospheric carbon dioxide was higher than present. This is especially the case given the difficulty of climate models in simulating past warm climates. This study explores the sensitivity of the simulated pre-PETM and PETM periods to change in cloud condensation nuclei (CCN) and microphysical properties of liquid water clouds. Assuming lower levels of CCN for both of these periods leads to significant warming, especially at high latitudes. The study indicates that past differences in cloud properties may be an important factor in accurately simulating past warm climates. Importantly, additional shortwave warming from such a mechanism would imply lower required atmospheric CO2 concentrations for simulated surface temperatures to be in reasonable agreement with proxy data for the Eocene.

Towards a Comparative Index of Seaport Climate-Risk: Development of Indicators from Open Data

Science.gov (United States)

McIntosh, R. D.; Becker, A.

2016-02-01

Seaports represent an example of coastal infrastructure that is at once critical to global trade, constrained to the land-sea interface, and exposed to weather and climate hazards. Seaports face impacts associated with projected changes in sea level, sedimentation, ocean chemistry, wave dynamics, temperature, precipitation, and storm frequency and intensity. Port decision-makers have the responsibility to enhance resilience against these impacts. At the multi-port (regional or national) scale, policy-makers must prioritize adaptation efforts to maximize the efficiency of limited physical and financial resources. Prioritization requires comparing across seaports, and comparison requires a standardized assessment method, but efforts to date have either been limited in scope to exposure-only assessments or limited in scale to evaluate one port in isolation from a system of ports. In order to better understand the distribution of risk across ports and to inform transportation resilience policy, we are developing a comparative assessment method to measure the relative climate-risk faced by a sample of ports. Our mixed-methods approach combines a quantitative, data-driven, indicator-based assessment with qualitative data collected via expert-elicitation. In this presentation, we identify and synthesize over 120 potential risk indicators from open data sources. Indicators represent exposure, sensitivity, and adaptive capacity for a pilot sample of 20 ports. Our exploratory data analysis, including Principal Component Analysis, uncovered sources of variance between individual ports and between indicators. Next steps include convening an expert panel representing the perspectives of multiple transportation system agencies to find consensus on a suite of robust indicators and metrics for maritime freight node climate risk assessment. The index will be refined based on expert feedback, the sample size expanded, and additional indicators sought from closed data sources

Climate change as an ecosystem architect: implications to rare plant ecology, conservation, and restoration

Science.gov (United States)

Constance I. Millar

2003-01-01

Recent advances in earth system sciences have revealed significant new information relevant to rare plant ecology and conservation. Analysis of climate change at high resolution with new and precise proxies of paleotemperatures reveals a picture over the past two million years of oscillatory climate change operating simultaneously at multiple timescales. Low-frequency...

Oxygen Isotopes Archived in Subfossil Chironomids: Advancing a Promising Proxy for Lake Water Isotopes

Science.gov (United States)

Lasher, G. E.; Axford, Y.; Blair, N. E.

2017-12-01

Oxygen isotopes measured in subfossil chironomid head capsules (aquatic insect remains) in lake sediments are beginning to offer paleoclimate insights from previously under-studied areas of the world. Since the first published pilot study demonstrated the potential of chironomid δ18O to record lake water δ18O (Wooller et al., 2004), subsequent work has refined our understanding of this proxy: confirming via lab cultures that growth water controls head capsule δ18O (Wang et al., 2009), refining laboratory pretreatment protocols, and further validating the method by demonstrating strong agreement between carbonate and chironomid-derived paleo-isotope records (Verbruggen et al., 2009, 2010, 2011). However, outstanding questions remain, including the seasonality of chironomid growth, possible species-dependent vital effects, and diagenetic effects on the protein-chitin complex that comprise chironomid cuticles. To address some of these questions, we summarize available data from paired modern chironomid-lake water δ18O values from around the world and discuss climatic and environmental factors affecting chironomid isotopic signatures. We also present new data on the resistance of these subfossils to diagenesis and degradation throughout the late Quaternary using Fourier Transform Infrared Spectroscopy (FT-IR) and Pyrolysis Gas Chromatography Mass Spectrometry (Py-GC/MS) of chironomid remains up to >100,000 years old. As chironomids are nearly ubiquitous in lakes globally and, we argue, molecularly stable through glacial and interglacial cycles, this proxy has the potential to greatly expand the spatial and temporal resolution of Quaternary paleo-isotopes and thus climate records. In addition to reviewing and presenting new methodological advances, we also present applications of chironomid δ18O from millennial- to centennial-scale Holocene Greenland lake records.

Understanding linkages between global climate indices and terrestrial water storage changes over Africa using GRACE products.

Science.gov (United States)

Anyah, R O; Forootan, E; Awange, J L; Khaki, M

2018-09-01

Africa, a continent endowed with huge water resources that sustain its agricultural activities is increasingly coming under threat from impacts of climate extremes (droughts and floods), which puts the very precious water resource into jeopardy. Understanding the relationship between climate variability and water storage over the continent, therefore, is paramount in order to inform future water management strategies. This study employs Gravity Recovery And Climate Experiment (GRACE) satellite data and the higher order (fourth order cumulant) statistical independent component analysis (ICA) method to study the relationship between terrestrial water storage (TWS) changes and five global climate-teleconnection indices; El Niño-Southern Oscillation (ENSO), North Atlantic Oscillation (NAO), Madden-Julian Oscillation (MJO), Quasi-Biennial Oscillation (QBO) and the Indian Ocean Dipole (IOD) over Africa for the period 2003-2014. Pearson correlation analysis is applied to extract the connections between these climate indices (CIs) and TWS, from which some known strong CI-rainfall relationships (e.g., over equatorial eastern Africa) are found. Results indicate unique linear-relationships and regions that exhibit strong linkages between CIs and TWS. Moreover, unique regions having strong CI-TWS connections that are completely different from the typical ENSO-rainfall connections over eastern and southern Africa are also identified. Furthermore, the results indicate that the first dominant independent components (IC) of the CIs are linked to NAO, and are characterized by significant reductions of TWS over southern Africa. The second dominant ICs are associated with IOD and are characterized by significant increases in TWS over equatorial eastern Africa, while the combined ENSO and MJO are apparently linked to the third ICs, which are also associated with significant increase in TWS changes over both southern Africa, as well as equatorial eastern Africa. Copyright © 2018

Climate change likely to reduce orchid bee abundance even in climatic suitable sites.

Science.gov (United States)

Faleiro, Frederico Valtuille; Nemésio, André; Loyola, Rafael

2018-06-01

Studies have tested whether model predictions based on species' occurrence can predict the spatial pattern of population abundance. The relationship between predicted environmental suitability and population abundance varies in shape, strength and predictive power. However, little attention has been paid to the congruence in predictions of different models fed with occurrence or abundance data, in particular when comparing metrics of climate change impact. Here, we used the ecological niche modeling fit with presence-absence and abundance data of orchid bees to predict the effect of climate change on species and assembly level distribution patterns. In addition, we assessed whether predictions of presence-absence models can be used as a proxy to abundance patterns. We obtained georeferenced abundance data of orchid bees (Hymenoptera: Apidae: Euglossina) in the Brazilian Atlantic Forest. Sampling method consisted in attracting male orchid bees to baits of at least five different aromatic compounds and collecting the individuals with entomological nets or bait traps. We limited abundance data to those obtained by similar standard sampling protocol to avoid bias in abundance estimation. We used boosted regression trees to model ecological niches and project them into six climate models and two Representative Concentration Pathways. We found that models based on species occurrences worked as a proxy for changes in population abundance when the output of the models were continuous; results were very different when outputs were discretized to binary predictions. We found an overall trend of diminishing abundance in the future, but a clear retention of climatically suitable sites too. Furthermore, geographic distance to gained climatic suitable areas can be very short, although it embraces great variation. Changes in species richness and turnover would be concentrated in western and southern Atlantic Forest. Our findings offer support to the ongoing debate of suitability

Fighting terrorism in Africa by proxy

DEFF Research Database (Denmark)

Olsen, Gorm Rye

2014-01-01

The French intervention in Mali in early 2013 emphasizes that the decision-makers in Paris, Brussels, and Washington considered the establishment of the radical Islamist regime in Northern Mali a threat to their security interests. The widespread instability including the rise of radical Islamist...... groups in Somalia was perceived as a threat to western interests. It is the core argument of the paper if western powers decide to provide security in Africa, they will be inclined to use proxy instead of deploying own troops. Security provision by proxy in African means that African troops are doing...

Among nonagenarians, congruence between self-rated and proxy-rated health was low but both predicted mortality.

Science.gov (United States)

Vuorisalmi, Merja; Sarkeala, Tytti; Hervonen, Antti; Jylhä, Marja

2012-05-01

The congruence between self-rated global health (SRH) and proxy-rated global health (PRH), the factors associated with congruence between SRH and PRH, and their associations with mortality are examined using data from the Vitality 90+ study. The data consist of 213 pairs of subjects--aged 90 years and older--and proxies. The relationship between SRH and PRH was analyzed by chi-square test and Cohen's kappa. Logistic regression analysis was used to find out the factors that are associated with the congruence between health ratings. The association between SRH and PRH with mortality was studied using Cox proportional hazard models. The subjects rated their health more negatively than the proxies. Kappa value indicated only slight congruence between SRH and PRH, and they also predicted mortality differently. Good self-reported functional ability was associated with congruence between SRH and PRH. The results imply that the evaluation processes of SRH and PRH differ, and the measures are not directly interchangeable. Both measures are useful health indicators in very old age but SRH cannot be replaced by PRH in analyses. Copyright © 2012 Elsevier Inc. All rights reserved.

Impact of Earth's orbit and freshwater fluxes on Holocene climate mean seasonal cycle and ENSO characteristics

Energy Technology Data Exchange (ETDEWEB)

Braconnot, P.; Zheng, W. [unite mixte CEA-CNRS-UVSQ, Laboratoire des Sciences du climat et de l' Environnement, Gif-sur-Yvette Cedex (France); Luan, Y. [unite mixte CEA-CNRS-UVSQ, Laboratoire des Sciences du climat et de l' Environnement, Gif-sur-Yvette Cedex (France); Chinese Academy of Sciences (CAS), State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG), Institute of Atmospheric Physics (IAP), Beijing (China); Graduate University of Chinese Academy of Sciences, Beijing (China); Brewer, Simon [University of Wyoming, Department of Botany, Laramie, WY (United States)

2012-03-15

We use a state-of-the-art 3-dimensional coupled model to investigate the relative impact of long term variations in the Holocene insolation forcing and of a freshwater release in the North Atlantic. We show that insolation has a greater effect on seasonality and La Nina events and is the major driver of sea surface temperature changes. In contrast, the variations in precipitation reflect changes in El Nino events. The impact of ice-sheet melting may have offset the impact of insolation on El Nino Southern Oscillation variability at the beginning of the Holocene. These simulations provide a coherent framework to refine the interpretation of proxy data and show that changes in seasonality may bias the projection of relationships established between proxy indicators and climate variations in the east Pacific from present day records. (orig.)

Similarity indices of meteo-climatic gauging stations: definition and comparison.

Science.gov (United States)

Barca, Emanuele; Bruno, Delia Evelina; Passarella, Giuseppe

2016-07-01

Space-time dependencies among monitoring network stations have been investigated to detect and quantify similarity relationships among gauging stations. In this work, besides the well-known rank correlation index, two new similarity indices have been defined and applied to compute the similarity matrix related to the Apulian meteo-climatic monitoring network. The similarity matrices can be applied to address reliably the issue of missing data in space-time series. In order to establish the effectiveness of the similarity indices, a simulation test was then designed and performed with the aim of estimating missing monthly rainfall rates in a suitably selected gauging station. The results of the simulation allowed us to evaluate the effectiveness of the proposed similarity indices. Finally, the multiple imputation by chained equations method was used as a benchmark to have an absolute yardstick for comparing the outcomes of the test. In conclusion, the new proposed multiplicative similarity index resulted at least as reliable as the selected benchmark.

Review of probabilistic pollen-climate transfer methods

Science.gov (United States)

Ohlwein, Christian; Wahl, Eugene R.

2012-01-01

Pollen-climate transfer methods are reviewed from a Bayesian perspective and with a special focus on the formulation of uncertainties. This approach is motivated by recent developments of spatial multi-proxy Bayesian hierarchical models (BHM), which allow synthesizing local reconstructions from different proxies for a spatially complete picture of past climate. In order to enhance the pollen realism in these models we try to bridge the gap between spatial statistics and paleoclimatology and show how far classical pollen-climate transfer concepts such as regression methods, mutual climatic range, modern analogues, plant functional types, and biomes can be understood in novel ways by refining the data models used in BHMs. As a case study, we discuss modeling of uncertainty by introducing a new probabilistic pollen ratio model, which is a simplified variation of the modern analogue technique (MAT) including the concept of response surfaces and designed for later inclusion in a spatial multiproxy BHM. Applications to fossil pollen data from varved sediments in three nearby lakes in west-central Wisconsin, USA and for a Holocene fossil pollen record from southern California, USA provide local climate reconstructions of summer temperature for the past millennium and the Holocene respectively. The performance of the probabilistic model is generally similar in comparison to MAT-derived reconstructions using the same data. Furthermore, the combination of co-location and precise dating for the three fossil sites in Wisconsin allows us to study the issue of site-specific uncertainty and to test the assumption of ergodicity in a real-world example. A multivariate ensemble kernel dressing approach derived from the post-processing of climate simulations reveals that the overall interpretation based on the individual reconstructions remains essentially unchanged, but the single-site reconstructions underestimate the overall uncertainty.

A persistent Holocene wetting trend in arid central Asia, with wettest conditions in the late Holocene, revealed by multi-proxy analyses of loess-paleosol sequences in Xinjiang, China

Science.gov (United States)

Chen, Fahu; Jia, Jia; Chen, Jianhui; Li, Guoqiang; Zhang, Xiaojian; Xie, Haichao; Xia, Dunsheng; Huang, Wei; An, Chengbang

2016-08-01

There are significant differences in the interpretation of the moisture (precipitation) history of arid central Asia (ACA) during the Holocene, as inferred on one hand from speleothem oxygen isotope records, and on the other from lake sediments. Here we present the results of measurements of climatically-sensitive magnetic properties and soil color from four well-dated loess-paleosol sequences from the northern slopes of the Tienshan Mountains and the Yili River valley, Xinjiang, China, in the core area of ACA. Our results demonstrate that the characteristic Holocene paleosol, indicating relatively moist conditions, generally formed after ∼6 ka (1 ka = 1000 cal yr BP) in the study region, and that the accumulation of unweathered loess prevailed during the early Holocene, indicating a dry climate at that time. The magnetic proxies further reveal a trend of generally increasing moisture since the Last Glacial Maximum, with the wettest climate occurring during the late Holocene. This trend of increasing moisture during the Holocene is representative of the Xinjiang region and possibly of the whole of the core area of ACA, and is in marked contrast both to the mid-Holocene moisture maximum observed in the East Asian summer monsoon region and to the general decrease in the strength of the Indian summer monsoon since the early Holocene. Our findings are supported by the results of a climate simulation which indicate a trend of increasing summer and winter precipitation during the Holocene in the core area of ACA, caused mainly by an increase in the strength of the westerlies effected by an increasing latitudinal insolation gradient and by a negative trend of the Arctic Oscillation (AO) or North Atlantic Oscillation (NAO).

Holocene seasonal variability inferred from multiple proxy records from Crevice Lake, Yellowstone National Park, USA

Science.gov (United States)

Whitlock, Cathy; Dean, Walter E.; Fritz, Sherilyn C.; Stevens, Lora R.; Stone, Jeffery R.; Power, Mitchell J.; Rosenbaum, Joseph R.; Pierce, Kenneth L.; Bracht-Flyr, Brandi B.

2012-01-01

the Roman Warm Period (~ 2000 cal yr BP) and Medieval Climate Anomaly (1200–800 cal yr BP). Long springs and mild summers occurred during the Little Ice Age, and these conditions persist to the present. Although the proxy data indicate effectively wet summer conditions in the early Holocene and drier conditions in the middle and late Holocene, none point specifically to changes in summer precipitation as the cause. Instead, summer conditions were governed by multi-seasonal controls on effective moisture that operated over multiple time scales.

Regionalisation of the recent and potential future climate of Central Asia. Modelling on the basis of direct climate data. Final report; Regionalisierung der rezenten und potentiell-zukuenftigen Klimaverhaeltnisse Zentralasiens. Modellierung auf Basis von direkten Klimadaten, geomorphologisch-palaeooekologischen Befunden und GCM-Simulationen. Schlussbericht

Energy Technology Data Exchange (ETDEWEB)

Boehner, J; Haselein, F; Hoffmann, H; Klinge, M; Lehmkuhl, F

2001-07-01

During the research project, the scientific base for the methodological coupling of GCM-Simulations and relief parametrisations for a spatially distributed downscaling scheme and for the detection of climatic controlled geomorphologic process regions was founded. The results of the application of the downscaling procedure and the detected climatic determinants of the recent geomorphologic process regions serve as the actualistic base for a proxy based climatic reconstruction as well as for the prognosis of potential future climatic impacts on the environment of Central and High Mountain Asia. For the Last Glacial Maximum (LGM), the spatial distribution of temperature and precipitation of Central- and High Mountain Asia was reconstructed and compared to the downscaling results of GCM-Paleo simulations (ECHAM). Due to the possibility of a direct parameterisation of GCM generated circulation variables and complex relief parameters for the regionalisation of climatic variables and geomorphologic process regions, the validation of ECHAM paleo simulations was also possible by comparing the proxy based reconstruction of the late quaternary environment to the modelled environment as derived from the application of ECHAM LGM simulations. For the assessment of potential future climatic impacts on the natural environment, alternative SRES emission scenarios are taken into account to detect the range of possible future changes in the distribution of Central Asia mountain belts and climatic controlled geomorphologic process regions. (orig.) [German] Im Rahmen des Forschungsprojektes wurden die Grundlagen zur methodisch-konzeptionellen Koppelung von GCM-Simulationen mit Reliefparametrisierungen zur raeumlich hochaufloesenden Klimaregionalisierung sowie zur Erfassung und quantitativen Eingrenzung klimatisch determinierter Prozessregionen geschaffen, die die aktualistische Basis fuer Klimarekonstruktionen auf Basis von Proxies aber auch die Grundlage fuer geomorphologisch

Applicability of a cognitive questionnaire in the elderly and proxy

Directory of Open Access Journals (Sweden)

Renata Areza Fegyveres

Full Text Available Abstract The Informant Questionnaire on Cognitive Decline in the Elderly with the Proxy (IQCODE was developed as a screening tool for cognition alterations. Objectives: 1 To verify the applicability of IQCODE in the elderly with limited schooling, 2 To verify the reliability of the responses supplied by the aged and their proxies. Methods: Individuals of a Community Group were evaluated using the Mini-Mental State Examination (MMSE, IQCODE and Geriatric Depression Scale (GDS. The IQCODE was applied to informants and proxies. Results: We analyzed 44 individuals, aged between 58-82 years (M=66.8, SD=5.97 with mean elderly-schooling level of 3.75, SD=2.82 and 44 proxies aged 44.5 (SD=13.3, with mean schooling level of 8.25 (SD=4.3. The mean GDS was 8.22, SD=4.90 and 13 participants presented a score suggestive of depressive symptoms. The mean elderly IQCODE score was 3.26, SD=0.69 and 3.21, SD=0.65, for proxy responses. There was no statistical difference between these means. On the MMSE, the mean score was 24.20, SD=4.14 and 18 participants presented scores below the cut-off. The IQCODE answers by the elderly in this latter group were more congruent with MMSE than the answers of proxies. Conclusions: The applicability of the IQCODE in a population with little schooling was verified in that the proxy-report was similar to the elderly report. We can affirm that the elderly answers were more accurate than the proxies, as they were closer to MMSE score. The inclusion of a greater number of participants from community-dwelling settings is necessary to confirm the results obtained in this study.

On the uncertainties associated with using gridded rainfall data as a proxy for observed

Directory of Open Access Journals (Sweden)

C. R. Tozer

2012-05-01

Full Text Available Gridded rainfall datasets are used in many hydrological and climatological studies, in Australia and elsewhere, including for hydroclimatic forecasting, climate attribution studies and climate model performance assessments. The attraction of the spatial coverage provided by gridded data is clear, particularly in Australia where the spatial and temporal resolution of the rainfall gauge network is sparse. However, the question that must be asked is whether it is suitable to use gridded data as a proxy for observed point data, given that gridded data is inherently "smoothed" and may not necessarily capture the temporal and spatial variability of Australian rainfall which leads to hydroclimatic extremes (i.e. droughts, floods. This study investigates this question through a statistical analysis of three monthly gridded Australian rainfall datasets – the Bureau of Meteorology (BOM dataset, the Australian Water Availability Project (AWAP and the SILO dataset. The results of the monthly, seasonal and annual comparisons show that not only are the three gridded datasets different relative to each other, there are also marked differences between the gridded rainfall data and the rainfall observed at gauges within the corresponding grids – particularly for extremely wet or extremely dry conditions. Also important is that the differences observed appear to be non-systematic. To demonstrate the hydrological implications of using gridded data as a proxy for gauged data, a rainfall-runoff model is applied to one catchment in South Australia initially using gauged data as the source of rainfall input and then gridded rainfall data. The results indicate a markedly different runoff response associated with each of the different sources of rainfall data. It should be noted that this study does not seek to identify which gridded dataset is the "best" for Australia, as each gridded data source has its pros and cons, as does gauged data. Rather, the intention is

Munchausen syndrome by proxy

Directory of Open Access Journals (Sweden)

Jovanović Aleksandar A.

2005-01-01

Full Text Available This review deals with bibliography on Munchausen syndrome by proxy (MSbP. The name of this disorder was introduced by English psychiatrist Roy Meadow who pointed to diagnostic difficulties as well as to serious medical and legal connotations of MSbP. MSbP was classified in DSM-IV among criteria sets provided for further study as "factitious disorder by proxy", while in ICD-10, though not explicitly cited, MSbP might be classified as "factitious disorders" F68.1. MSbP is a special form of abuse where the perpetrator induces somatic or mental symptoms of illness in the victim under his/her care and then persistently presents the victims for medical examinations and care. The victim is usually a preschool child and the perpetrator is the child's mother. Motivation for such pathological behavior of perpetrator is considered to be unconscious need to assume sick role by proxy while external incentives such as economic gain are absent. Conceptualization of MSbP development is still in the domain of psychodynamic speculation, its course is chronic and the prognosis is poor considering lack of consistent, efficient and specific treatment. The authors also present the case report of thirty-three year-old mother who had been abusing her nine year-old son both emotionally and physically over the last several years forcing him to, together with her, report to the police, medical and educational institutions that he had been the victim of rape, poisoning and beating by various individuals, especially teaching and medical staff. Mother manifested psychosis and her child presented with impaired cognitive development, emotional problems and conduct disorder.

Evaluation of patient and proxy responses on the activity measure for postacute care.

Science.gov (United States)

Jette, Alan M; Ni, Pengsheng; Rasch, Elizabeth K; Appelman, Jed; Sandel, M Elizabeth; Terdiman, Joseph; Chan, Leighton

2012-03-01

Our objective was to examine the agreement between adult patients with stroke and family member or clinician proxies in activity measure for postacute care (AM-PAC) summary scores for daily activity, basic mobility, and applied cognitive function. This study involved 67 patients with stroke admitted to a hospital within the Kaiser Permanente of Northern California system and were participants in a parent study on stroke outcomes. Each participant and proxy respondent completed the AM-PAC by personal or telephone interview at the point of hospital discharge or during ≥1 transitions to different postacute care settings. The results suggest that for patients with a stroke proxy, AM-PAC data are robust for family or clinician proxy assessment of basic mobility function and clinician proxy assessment of daily activity function, but less robust for family proxy assessment of daily activity function and for all proxy groups' assessments of applied cognitive function. The pattern of disagreement between patient and proxy was, on average, relatively small and random. There was little evidence of systematic bias between proxy and patient reports of their functional status. The degree of concordance between patient and proxy was similar for those with moderate to severe strokes compared with mild strokes. Patient and proxy ratings on the AM-PAC achieved adequate agreement for use in stroke research when using proxy respondents could reduce sample selection bias. The AM-PAC data can be implemented across institutional as well as community care settings while achieving precision and reducing respondent burden.

How well are the climate indices related to the GRACE-observed total water storage changes in China?

Science.gov (United States)

Devaraju, B.; Vishwakarma, B.; Sneeuw, N. J.

2017-12-01

The fresh water availability over land masses is changing rapidly under the influence of climate change and human intervention. In order to manage our water resources and plan for a better future, we need to demarcate the role of climate change. The total water storage change in a region can be obtained from the GRACE satellite mission. On the other hand, many climate change indicators, for example ENSO, are derived from sea surface temperature. In this contribution we investigate the relationship between the total water storage change over China with the climate indices using statistical time-series decomposition techniques, such as Seasonal and Trend decomposition using Loess (STL), Principal Component Analysis (PCA) and Canonical Correlation Analysis (CCA). The anomalies in climate variables, such as sea surface temperature, are responsible for anomalous precipitation and thus an anomalous total water storage change over land. Therefore, it is imperative that we use a GRACE product that can capture anomalous water storage changes with unprecedented accuracy. Since filtering decreases the sensitivity of GRACE products substantially, we use the data-driven method of deviation for recovering the signal lost due to filtering. To this end, we are able to obtain the spatial fingerprint of individual climate index on total water storage change observed over China.

Proxy-rated quality of life in Alzheimer's disease

DEFF Research Database (Denmark)

Vogel, Asmus; Bhattacharya, Suvosree; Waldorff, Frans Boch

2012-01-01

The study investigated the change in proxy rated quality of life (QoL) of a large cohort of home living patients with Alzheimer's disease (AD) over a period of 36 months.......The study investigated the change in proxy rated quality of life (QoL) of a large cohort of home living patients with Alzheimer's disease (AD) over a period of 36 months....

Climate Reconstruction on the Growth of Teak in Umphang Wildlife Sanctuary, Thailand

Directory of Open Access Journals (Sweden)

Pichit Lumyai

2017-11-01

Full Text Available Teak is an example of proxy data that can be used to indirectly deduce past climatic conditions. The objective of this study was to investigate the relationship between teak growth and climate data in western Thailand. Dendrochronological techniques were used to analyze 52 sample cores from Umphang Wildlife Sanctuary. The crossdated ring width data could be extended back 127 years (1886-2012. The relationship between ring-width index and climatic data indicated a positive correlation (p<0.01 with the current year total rainfall in March and June. Thus, only March and June data were used to reconstruct the annual ring width index which indicated a downward trend in the reconstructed rainfall. Considering the March and June average total rainfall, a wet period occurred in 1887-1895 and this gradually decreased to a stable pattern in 1927-1945 with a further decline to another stable level in 1957-1964. Similarly, the dry periods occurring in 1896-1926, 1946-1955, 1965-1981 and 1982-2012 could explain the high fluctuations in rainfall. Periods of 2.2-2.7 and 25.2 years were found to be common with the variations in the El Niño-Southern Oscillation. In conclusion, teak growth information can be used to monitor global warming events.

Longitudinal proxy measurements in multiple sclerosis: patient-proxy agreement on the impact of MS on daily life over a period of two years

Directory of Open Access Journals (Sweden)

Thompson Alan J

2008-02-01

Full Text Available Abstract Background The use of self-report measurements in clinical settings is increasing. However, in patients with limitations that interfere with reliable self-assessment such as cognitive impairment or mood disturbances, as may be the case in multiple sclerosis (MS, data collection might be problematic. In these situations, information obtained from proxy respondents (e.g. partners may replace self-ratings. The aim of this study was to examine the value of proxy ratings at separate points in time and to assess patient-proxy agreement on possible changes in disease impact of MS. Methods Fifty-six MS patients and their partners completed the Multiple Sclerosis Impact Scale (MSIS-29 at baseline and follow-up, two years later. Patient-proxy agreement was assessed at both time points by calculating intraclass correlation coefficients (ICCs, exact and global agreement and the mean directional differences between groups. Agreement of change over time was assessed by calculating ICCs between change scores. In parallel, global ratings of both patients and proxy respondents of the extent to which the patient had improved or deteriorated over the past two years were collected to validate possible changes on the MSIS-29. Results At both time points, agreement on the physical scale was higher than agreement on the psychological scale (ICCs at baseline were 0.81 for the physical scale and 0.72 for the psychological scale; at follow-up, the ICC values were 0.86 and 0.65 respectively. At follow-up, statistically significant mean differences between patients and proxies were noted for the physical scale (-4.8 ± 12.7, p = 0.006 and the psychological scale (-8.9 ± 18.8, p = 0.001. Agreement between change scores on the MSIS-29 was fair (ICC Conclusion Proxy respondents could act as a reliable source of information in cross-sectional studies. Moreover, results suggested that agreement on change over time might be better for proxy respondents compared to