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Sample records for climatic record deduced

  1. Proxy late Holocene climatic record deduced from northwest Alaska beach ridges

    SciTech Connect

    Mason, O.K.; Jordan, J.W.

    1992-03-01

    A climatically sensitive, oscillatory pattern of progradation and erosion is revealed in late Holocene accretionary sand ridge and barrier island complexes of Seward Peninsula, northwest Alaska. Archaeological and geological radiocarbon dates constrain the chronology for the Cape Espenberg beach ridge plain and the Shishmaref barrier islands, 50 km to the southwest. Cape Espenberg, the depositional sink for the northeastward longshore transport system, contains the oldest sedimentary deposits: 3700 +/- 90 B.P. (B-23170) old grass from a paleosol in a low dune. The oldest date on the Shishmaref barrier islands is 1550 +/- 70 B.P. (B-23183) and implies that the modern barrier is a comparatively recent phenomenon. Late Holocene sedimentation along the Seward Peninsula varied between intervals of rapid progradation and erosion. Rapid progradation predominated from 4000-3300 B.P. and from 2000-1200 B.P., with the generation of low beach ridges without dunes, separated by wide swales. During erosional periods higher dunes built atop beach ridges: as between 3300-2000 B.P. and intermittently from 1000 B.P. to the present. Dune formation correlates with the Neoglacial and Little Ice Age glacial advances and increased alluviation in northern and central Alaska, while rapid progradation is contemporaneous with warmer intervals of soil and/or, peat formation atop alluvial terraces, dated to 4000-3500 and 2000-1000 B.P.

  2. Climate dynamics from 17 to 7 kyr BP deduced from a new pollen record from Tenaghi Philippon in comparison with marine palynological data from the northern Aegean Sea

    NASA Astrophysics Data System (ADS)

    Kotthoff, U.; Pross, J.; Müller, U. C.; Dormoy, I.; Peyron, O.; Bordon, A.; Schmiedl, G.

    2009-04-01

    The time interval from 17 to 7 kyr BP is characterized by pronounced climate variability. Among the climatic setbacks during that time, the most prominent are the Younger Dryas (YD) and the 8.2 ka event. The impact of these setbacks on vegetation development is relatively well understood for higher-latitude settings particularly in Central and SW Europe. However, there is still a lack of high-resolution vegetation and climate data for the eastern Mediterranean region, although this region is an ideal natural laboratory for analyzing the effects of short-term climatic change on terrestrial environments due to its intermediate position between the higher-latitude and lower-latitude climate systems. In light of the above, we used a terrestrial core from Tenaghi Philippon, NE Greece, to carry out pollen-based vegetation and climate reconstructions. These indicate that both temperature and precipitation controlled vegetation dynamics until ~15 kyr BP. Between ~15 and ~12.7 kyr BP, temperatures were already comparable to early Holocene circumstances, thus changes in moisture availability appear to have been of major importance. During the interstadials of the Bølling/Allerød interstadial complex (BAC), moisture availability appears higher at Tenaghi Phillipon than during the preceding interval. The following Younger Dryas, although drier and colder than the preceding interstadials of the BAC, appears more humid/warmer than the preceding cold intervals, i.e. the Older and Oldest Dryas and the Pleniglacial. These results are in opposite to findings from a neighbouring marine palynomorph record, where the YD appears to be the coldest/driest interval between 17 and 7 kyr BP, implied by both pollen- and dinocyst-based reconstructions. The early Holocene was punctuated by several short-term climate events. Among these, the North-Atlantic-related 8.2 ka event is most strongly pronounced at Tenaghi Philippon, with winter temperatures declining by almost 4° C, in opposite to

  3. Climate change deduced from isotopes in tree rings

    SciTech Connect

    Pendall, E.G.; Leavitt, S.W.

    1997-11-01

    This paper describes the theory of carbon, hydrogen, and oxygen isotopic signatures in cellulose for the purpose of paleoclimatic reconstruction. Mechanisms governing tree ring cellulose isotopic variability are investigated, and applications to the southwestern United States are delineated. A monitoring program of pinyon trees and comparison to climatic parameters is briefly described. Variables measured included deviations in hydrogen and oxygen-18 isotopic composition in precipitation, soil water, stem and leaf water, and atmospheric vapor. Water from phloem tissue was found to be isotopically identical to the xylem sap, suggesting that cellulose precursors can exchange isotopically with source water before cellulose is made in the trunk, thus removing most of the isotopic signal from the leaves. Overall results suggest that, on arid sites in the southwestern US receiving adequate summer rain, a precipitation seasonality signal may be recorded. 21 refs., 2 figs.

  4. Corals as climate recorders

    USGS Publications Warehouse

    Flannery, Jennifer A.; Poore, Richard Z.

    2010-01-01

    The U.S. Geological Survey (USGS) Coral Reef Ecosystem Studies (CREST) Project is analyzing corals from various sites in the Caribbean region, Dry Tortugas National Park, Biscayne National Park, other areas of the Florida Keys, and the Virgin Islands. The objective of this project is to develop records of past environmental change to better our understanding of climate variability. The records are being used to document changes over the last few centuries and to determine how corals and coral reefs have responded to any changes.

  5. Precipitation Climate Data Records

    NASA Astrophysics Data System (ADS)

    Nelson, B. R.; Prat, O.; Vasquez, L.

    2015-12-01

    Five precipitation CDRs are now or soon will be transitioned to NOAA's CDR program. These include the PERSIANN data set, which is a 30-year record of daily adjusted global precipitation based on retrievals from satellite microwave data using artificial neural networks. The AMSU-A/B/Hydrobundle is an 11-year record of precipitable water, cloud water, ice water, and other variables. CMORPH (the NOAA Climate Prediction Center Morphing Technique) is a 17-year record of daily and sub-daily adjusted global precipitation measured from passive microwave and infrared data at high spatial and temporal resolution. GPCP (the Global Precipitation Climatology Project) is an approximately 30-year record of monthly and pentad adjusted global precipitation and a 17-year record of daily adjusted global precipitation. The NEXRAD Reanalysis is a 10-year record of high resolution NEXRAD radar based adjusted CONUS-wide hourly and daily precipitation. This study provides an assessment of the existing and transitioned long term precipitation CDRs and includes the verification of the five precipitation CDRs using various methods including comparison with in-situ data sets and trend analysis. As all of the precipitation related CDRs are transitioned, long term analyses can be performed. Comparisons at varying scales (hourly, daily and longer) of the precipitation CDRs with in-situ data sets are provided as well as a first look at what could be an ensemble long term precipitation data record.

  6. Paleoclimate variability during the Blake geomagnetic excursion (MIS 5d) deduced from a speleothem record

    NASA Astrophysics Data System (ADS)

    Rossi, Carlos; Mertz-Kraus, Regina; Osete, María-Luisa

    2014-10-01

    To evaluate possible connections between climate and the Earth's magnetic field, we examine paleoclimate proxies in a stalagmite (PA-8) recording the Blake excursion (˜112-˜116.4 ka) from Cobre cave (N Spain). Trace element, δ13C, δ18O, δ234U, fluorescent lamination, growth rate, and paleomagnetic records were synchronized using a floating lamina-counted chronology constrained by U-Th dates, providing a high-resolution multi-proxy paleoclimate record for MIS 5d. The alpine cave setting and the combination of proxies contributed to improve the confidence of the paleoclimatic interpretation. Periods of relatively warm and humid climate likely favored forest development and resulted in high speleothem growth rates, arguably annual fluorescent laminae, low δ13C and [Mg], and increased [Sr] and [Ba]. Colder periods limited soil activity and drip water availability, leading to reduced speleothem growth, poor development of fluorescent lamination, enhanced water-rock interaction leading to increased [Mg], δ13C, and δ234U, and episodic flooding. In the coldest and driest period recorded, evaporation caused simultaneous 18O and 13C enrichments and perturbed the trace element patterns. The Blake took place in a relatively warm interestadial at the inception of the Last Glacial period, but during a global cooling trend recorded in PA-8 by an overall decrease of δ18O and growth rate and increasing [Mg]. That trend culminated in the cessation of growth between ˜112 and ˜101 ka likely due to the onset of local glaciation correlated with Greenland stadial 25. That trend is consistent with a link between low geomagnetic intensity and climate cooling, but it does not prove it. Shorter term changes in relative paleointensity (RPI) relate to climate changes recorded in PA-8, particularly a prominent RPI low from ˜114.5 to ˜113 ka coincident with a significant cooling indicated by all proxy records, suggesting a link between geomagnetic intensity and climate at millennial

  7. 600 yr High-Resolution Climate Reconstruction of the Atlantic Multidecadal Variability deduced from a Puerto Rican Speleothem

    NASA Astrophysics Data System (ADS)

    Winter, A.; Vieten, R.

    2015-12-01

    A multi-proxy speleothem study tracks the regional hydrological variability in Puerto Rico and highlights its close relation to the Atlantic Multidecadal Oscillation. Our proxy record extends instrumental observations 600 years into the past, and reveals the range of natural hydrologic variability for the region. A detailed interpretation and understanding of the speleothem climate record is achieved by the combination of multi-proxy measurements, thin section petrography, XRD analysis and cave monitoring results. The speleothem was collected in Cueva Larga, a one mile-long cave system that has been monitored since 2012. MC-ICPMS 230Th/U-dating reveals that the speleothem grew constantly over the last 600 years. Trace element ratios (Sr/Ca and Mg/Ca) as well as stable isotope ratios (δ18O and δ13C) elucidate significant changes in atmospheric precipitation at the site. Monthly cave monitoring results demonstrate that the epikarst system responds to multi-annual changes in seepage water recharge. The drip water isotope and trace element composition lack short term or seasonal variability. This hydrological system creates favorable conditions to deduce decadal climate variability from Cueva Larga's climate record. The speleothem time series mimics the most-recently published AMO reconstruction over the last 200 years with a time lag of 10-20 years. The time lag seems to results from slow atmospheric signal transmission through the epikarst but the effect of dating uncertainties cannot be ruled out. Warm SSTs in the North Atlantic are related to drier conditions in Puerto Rico. During times of decreased rainfall a relative increase in prior calcite precipitation seems to be the main process causing increased Mg/Ca trace element ratios. High trace element ratios correlate to higher δ13C values. The increase in both proxies indicates a shift towards time periods of decreased rainfall. Over the past 600 years there are two intervals of increased Mg/Ca and δ13C values

  8. 600 yr High-Resolution Climate Reconstruction of the Atlantic Multidecadal Oscillation deduced from a Puerto Rican Speleothem

    NASA Astrophysics Data System (ADS)

    Vieten, Rolf; Winter, Amos; Scholz, Denis; Black, David; Spoetl, Christoph; Winterhalder, Sophie; Koltai, Gabriella; Schroeder-Ritzrau, Andrea; Terzer, Stefan; Zanchettin, Davide; Mangini, Augusto

    2016-04-01

    A multi-proxy speleothem study tracks the regional hydrological variability in Puerto Rico and highlights its close relation to the Atlantic Multidecadal Oscillation (AMO) describing low-frequency sea-surface temperature (SST) variability in the North Atlantic ocean. Our proxy record extends instrumental observations 600 years into the past, and reveals the range of natural hydrologic variability for the region. A detailed interpretation and understanding of the speleothem climate record is achieved by the combination of multi-proxy measurements, thin section petrography, XRD analysis and cave monitoring results. The speleothem was collected in Cueva Larga, a one mile-long cave system that has been monitored since 2012. MC-ICPMS 230Th/U-dating reveals that the speleothem grew constantly over the last 600 years. Trace element ratios (Sr/Ca and Mg/Ca) as well as stable isotope ratios (δ18O and δ13C) elucidate significant changes in atmospheric precipitation at the site. Monthly cave monitoring results demonstrate that the epikarst system responds to multi-annual changes in seepage water recharge. The drip water isotope and trace element composition lack short term or seasonal variability. This hydrological system creates favorable conditions to deduce decadal climate variability from Cueva Larga's climate record. The speleothem time series mimics the most recent AMO reconstruction over the last 200 years (Svendsen et al., 2014) with a time lag of 10-20 years. The lag seems to results from slow atmospheric signal transmission through the epikarst but the effect of dating uncertainties cannot be ruled out. Warm SSTs in the North Atlantic are related to drier conditions in Puerto Rico. During times of decreased rainfall a relative increase in prior calcite precipitation seems to be the main process causing increased Mg/Ca trace element ratios. High trace element ratios correlate to higher δ13C values. The increase in both proxies indicates a shift towards time

  9. A Record of Climate Change

    ERIC Educational Resources Information Center

    Smith, Zach

    2007-01-01

    The hydrologic cycle is a very basic scientific principle. In this article, background information is presented on how the hydrologic cycle provides scientists with clues to understanding the history of Earth's climate. Also detailed is a web-based activity that allows students to learn about how scientists are able to piece together a record of…

  10. Climate stability as deduced from an idealized coupled atmosphere-ocean model

    SciTech Connect

    Tang, B.; Weaver, A.J.

    1995-04-01

    The stability of an idealized climate system is investigated using a simple coupled atmosphere-ocean box model. Motivated by the results from general circulation models. the main physical constraint imposed on the system is that the net radiation at the top of the atmosphere is fixed. The specification of an invariant equatorial atmospheric temperature. Consistent with paleoclimatic data, allows the hydrological cycle to be internally determined from the poleward heat transport budget, resulting in a model that has a plausible representation of the hydrological cycle-thermohaline circulation interaction. The model suggests that the stability and variability of the climate system depends fundamentally on the mean climatic state (total heat content of the system). When the total heat content of the climate system is low, a stable present-day equilibrium exists with high-latitude sinking. Conversely, when the total heat content is high, a stable equatorial sinking equilibrium exists. For a range of intermediate values of the total heat content, internal climatic oscillations can occur through a hydrological cycle-thermohaline circulation feedback process. Experiments conducted with the model reveal that under a 100-year 2xCO{sub 2} warming, the thermohaline circulation first collapses but then recovers. Under a 100-year 4 x CO{sub 2} warming, the thermohaline circulation collapses and remains collapsed. Recent paleoclimatic data suggest that the climate system may behave very differently for warmer climate. Our results suggest that this may be attributed to the enhanced poleward freshwater transport, which causes increased instability of the present-day thermohaline circulation. 50 refs., 4 figs., 1 tab.

  11. On the turnaround of stratospheric ozone trends deduced from the reevaluated Umkehr record of Arosa, Switzerland

    NASA Astrophysics Data System (ADS)

    Zanis, P.; Maillard, E.; Staehelin, J.; Zerefos, C.; Kosmidis, E.; Tourpali, K.; Wohltmann, I.

    2006-11-01

    In this work, we investigate the issue of the turnaround in ozone trends of the recently homogenized Umkehr ozone record of Arosa, Switzerland, which is the longest Umkehr data set, extending from 1956 to date, using different statistical methods. All methods show statistically significant negative ozone trends from 1970 to 1995 in the upper stratosphere (above 32.6 km) throughout the course of the year as well as in the lower stratosphere (below 23.5 km) mainly during winter to spring, which can be partially attributed to dynamical changes. Over the recent period (1996-2004) the year-round trends in the lower stratosphere become positive and are more positive during the winter to spring period. The results also show changes in upper stratospheric ozone trends after 1996, which are, however, not statistically significant at 95% if aerosol correction is applied on the retrieved data. This lack of significant trend changes during the recent period in the upper stratosphere is regionally coherent with recent results derived from upper stratospheric ozone data recorded by lidars, microwave radiometers, and satellite instruments at an adjacent location. Although the positive change in trends after 1996 both for upper and lower stratospheric ozone is in line with the reduction of the emissions of ozone-depleting substances from the successful implementation of the Montreal Protocol and its amendments, we recommend, because of lack of significance for the upper stratospheric trends, repeating this analysis in a few years in order to overcome ambiguous results for documentation of the turnaround of upper stratospheric ozone.

  12. Petrographically deduced triassic climate for the Deep River Basin, eastern piedmont of North Carolina

    SciTech Connect

    McCarn, S.T.; Mansfield, C.F.

    1985-01-01

    A petrographic comparison of Triassic, fluvial sandstones from the Deep River Basin in the eastern piedmont of North Carolina with nearby Holocene stream sands (1) indicates that he Triassic climate was more arid than today's and (2) distinguishes an eastern, more plutonic terrane from a western, more metamorphic source terrane. The paleoclimatic interpretation is based on differences in framework composition between modern and ancient sands of the same grain size, derived from the same rock type, transported similar distances and deposited in similar settings. The Triassic sandstones contain more lithic-fragments but less quartz than otherwise equivalent, modern sand in the Deep River Basin. Feldspar content is more complex, controlled by both source-rock composition and climate. Sand from the more plutonic terrane contains more feldspar and plutonic lithic-fragments than sand from the more metamorphic terrane, which contains more quartz and metamorphic lithic-fragments. This petrographic interpretation of the Triassic sandstones along with the presence of coal, limestone, chert and caliche in the middle of the section suggests that the Triassic climate was cyclic, changing from arid to humid and back to arid. Plate-tectonic reconstructions place the Deep River Basin between the Triassic equator and Tropic of cancer, where the easterly trade winds would predominate. Therefore, the arid portions of the cycle could have been due to a periodic, orographic, rain shadow formed as the result of intermittent movement along the Jonesboro Fault, creating a highland area east of the Deep River Basin.

  13. Atmospheric carbon dioxide and the climate record

    SciTech Connect

    Ellsaesser, H.W.

    1989-04-01

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

  14. Multi-scale Holocene Asian monsoon variability deduced from a twin-stalagmite record in southwestern China

    NASA Astrophysics Data System (ADS)

    Huang, Wei; Wang, Yongjin; Cheng, Hai; Edwards, Richard Lawrence; Shen, Chuan-Chou; Liu, Dianbing; Shao, Qingfeng; Deng, Chao; Zhang, Zhenqiu; Wang, Quan

    2016-07-01

    We present two isotopic (δ18O and δ13C) sequences of a twin-stalagmite from Zhuliuping Cave, southwestern China, with 230Th dates from 14.6 to 4.6 ka. The stalagmite δ18O record characterizes orbital- to decadal-scale variability of Asian summer monsoon (ASM) intensity, with the Holocene optimum period (HOP) between 9.8 and 6.8 ka BP which is reinforced by its co-varying δ13C data. The large multi-decadal scale amplitude of the cave δ18O indicates its high sensitivity to climate change. Four centennial-scale weak ASM events during the early Holocene are centered at 11.2, 10.8, 9.1 and 8.2 ka. They can be correlated to cold periods in the northern high latitudes, possibly resulting from rapid dynamics of atmospheric circulation associated with North Atlantic cooling. The 8.2 ka event has an amplitude more than two-thirds that of the Younger Dryas (YD), and is significantly stronger than other cave records in the Asia monsoon region, likely indicating a more severe dry climate condition at the cave site. At the end of the YD event, the δ13C record lags the δ18O record by 300-500 yr, suggesting a multi-centennial slow response of vegetation and soil processes to monsoon enhancement.

  15. Daily Temperature Records in a Warming Climate

    NASA Astrophysics Data System (ADS)

    Meehl, G. A.; Tebaldi, C.

    2014-12-01

    The ratio of daily record high maximum temperatures to daily record low minimum temperatures in the first decade of the 21st century was about 2 to 1. Previous model simulations also showed a comparable ratio, with projections of an increase in that ratio in the 21st century. Here we relate record highs and record lows to changing surface conditions in 1 degree and 0.5 degree resolution global coupled climate models for 20th and 21st century climate to address the issue of model resolution in simulating past and future changes of temperature extremes as represented by daily record highs and lows.

  16. Inferring climate variability from skewed proxy records

    NASA Astrophysics Data System (ADS)

    Emile-Geay, J.; Tingley, M.

    2013-12-01

    Many paleoclimate analyses assume a linear relationship between the proxy and the target climate variable, and that both the climate quantity and the errors follow normal distributions. An ever-increasing number of proxy records, however, are better modeled using distributions that are heavy-tailed, skewed, or otherwise non-normal, on account of the proxies reflecting non-normally distributed climate variables, or having non-linear relationships with a normally distributed climate variable. The analysis of such proxies requires a different set of tools, and this work serves as a cautionary tale on the danger of making conclusions about the underlying climate from applications of classic statistical procedures to heavily skewed proxy records. Inspired by runoff proxies, we consider an idealized proxy characterized by a nonlinear, thresholded relationship with climate, and describe three approaches to using such a record to infer past climate: (i) applying standard methods commonly used in the paleoclimate literature, without considering the non-linearities inherent to the proxy record; (ii) applying a power transform prior to using these standard methods; (iii) constructing a Bayesian model to invert the mechanistic relationship between the climate and the proxy. We find that neglecting the skewness in the proxy leads to erroneous conclusions and often exaggerates changes in climate variability between different time intervals. In contrast, an explicit treatment of the skewness, using either power transforms or a Bayesian inversion of the mechanistic model for the proxy, yields significantly better estimates of past climate variations. We apply these insights in two paleoclimate settings: (1) a classical sedimentary record from Laguna Pallcacocha, Ecuador (Moy et al., 2002). Our results agree with the qualitative aspects of previous analyses of this record, but quantitative departures are evident and hold implications for how such records are interpreted, and

  17. Vegetation history of central Chukotka deduced from permafrost paleoenvironmental records of the El'gygytgyn Impact Crater

    NASA Astrophysics Data System (ADS)

    Andreev, A. A.; Morozova, E.; Fedorov, G.; Schirrmeister, L.; Bobrov, A. A.; Kienast, F.; Schwamborn, G.

    2012-08-01

    Frozen sediments from three cores bored in the permafrost surrounding the El'gygytgyn Impact Crater Lake have been studied for pollen, non-pollen palynomorphs, plant macrofossils and rhizopods. The palynological study of these cores contributes to a higher resolution of time intervals presented in a poor temporal resolution in the lacustrine sediments; namely the Allerød and succeeding periods. Moreover, the permafrost records better reflect local environmental changes, allowing a more reliable reconstruction of the local paleoenvironments. The new data confirm that shrub tundra with dwarf birch, shrub alder and willow dominated the lake surroundings during the Allerød warming. Younger Dryas pollen assemblages reflect abrupt changes to grass-sedge-herb dominated environments reflecting significantly drier and cooler climate. Low shrub tundra with dwarf birch and willow dominate the lake vicinity at the onset of the Holocene. The find of larch seeds indicate its local presence around 11 000 cal yr BP and, thus a northward shift of treeline by about 100 km during the early Holocene thermal optimum. Forest tundra with larch and shrub alder stands grew in the area during the early Holocene. After ca. 3500 cal yr BP similar-to-modern plant communities became common in the lake vicinity.

  18. Vegetation history of Central Chukotka deduced from permafrost paleoenvironmental records of the El'gygytgyn Impact Crater

    NASA Astrophysics Data System (ADS)

    Andreev, A. A.; Morozova, E.; Fedorov, G.; Schirrmeister, L.; Bobrov, A. A.; Kienast, F.; Schwamborn, G.

    2012-04-01

    Frozen sediments from three cores bored in permafrost surrounding of the El'gygytgyn Impact Crater Lake have been studied for pollen, non-pollen palynomorphs, plant macrofossils, and rhizopods. The palynological study of the cores contributes to a higher resolution of time intervals presented in a poor temporal resolution in the lacustrine sediments; namely the Allerød and succeeding periods. Moreover, permafrost records better reflect local environmental changes, thus, allowing more reliable reconstruction of the local paleoenvironments. The new data confirm that shrub tundra with dwarf birch, shrub alder and willow dominated in the lake surroundings during the Allerød warming. Younger Dryas pollen assemblages reflect abrupt changes to grass-sedge-herb dominated environments reflecting significant climate deterioration. Low shrub tundra with dwarf birch and willow dominate the lake vicinity at the onset of the Holocene. The founds of larch seeds indicate its local presence around 11 000 cal. yr BP and, thus a northward shift of treeline by about 100 km during the early Holocene thermal optimum. Forest tundra with larch and shrub alder stands grew in the area during the early Holocene. After ca. 3500 cal. yr BP similar-to-modern plant communities became common in the lake vicinity.

  19. NOAA's Portfolio of Operational Climate Data Records

    NASA Astrophysics Data System (ADS)

    Newport, B. J.; Cecil, D.; Hutchins, C.; Preston, C.; Stachniewicz, J. S.; Wunder, D.

    2015-12-01

    NOAA's Climate Data Record (CDR) Program was established by the National Centers for Environmental Information (NCEI) (formerly the National Climatic Data Center) in order to develop and implement a robust, sustainable, and scientifically defensible approach to producing and preserving climate records from satellite data. Since its inception in 2009 the CDR Program has transitioned 30 CDRs developed by various research groups to an initial operational state at NCEI. As a result of this transition the CDR dataset, metadata, documentation, and source code are archived by NCEI and accessible to the public, and most of the datasets are being extended by the Principal Investigator with CDR Program support. Consistency is maintained by using a formal change control process, with reprocessing and re-archiving as needed. The current portfolio of operational CDRs includes 15 Atmospheric CDRs, four Oceanic CDRs, four Terrestrial CDRs, and seven Fundamental CDRs. The main features of the portfolio will be presented, along with some potential and emerging uses.

  20. Late Holocene climates of the Near East deduced from Dead Sea level variations and modern regional winter rainfall

    NASA Astrophysics Data System (ADS)

    Enzel, Yehouda; Bookman (Ken Tor), Revital; Sharon, David; Gvirtzman, Haim; Dayan, Uri; Ziv, Baruch; Stein, Mordechai

    2003-11-01

    The Dead Sea is a terminal lake of one of the largest hydrological systems in the Levant and may thus be viewed as a large rain gauge for the region. Variations of its level are indicative of the climate variations in the region. Here, we present the decadal- to centennial-resolution Holocene lake-level curve of the Dead Sea. Then we determine the regional hydroclimatology that affected level variations. To achieve this goal we compare modern natural lake-level variations and instrumental rainfall records and quantify the hydrology relative to lake-level rise, fall, or stability. To quantify that relationship under natural conditions, rainfall data pre-dating the artificial Dead Sea level drop since the 1960s are used. In this respect, Jerusalem station offers the longest uninterrupted pre-1960s rainfall record and Jerusalem rains serve as an adequate proxy for the Dead Sea headwaters rainfall. Principal component analysis indicates that temporal variations of annual precipitation in all stations in Israel north of the current 200 mm yr -1 average isohyet during 1940-1990 are largely synchronous and in phase (˜70% of the total variance explained by PC1). This station also represents well northern Jordan and the area all the way to Beirut, Lebanon, especially during extreme drought and wet spells. We (a) determine the modern, and propose the past regional hydrology and Eastern Mediterranean (EM) climatology that affected the severity and length of droughts/wet spells associated with multiyear episodes of Dead Sea level falls/rises and (b) determine that EM cyclone tracks were different in average number and latitude in wet and dry years in Jerusalem. The mean composite sea level pressure and 500-mb height anomalies indicate that the potential causes for wet and dry episodes span the entire EM and are rooted in the larger-scale northern hemisphere atmospheric circulation. We also identified remarkably close association (within radiocarbon resolution) between

  1. Modern climate challenges and the geological record

    USGS Publications Warehouse

    Cronin, Thomas M.

    2010-01-01

    Today's changing climate poses challenges about the influence of human activity, such as greenhouse gas emissions and land use changes, the natural variability of Earth's climate, and complex feedback processes. Ice core and instrumental records show that over the last century, atmospheric carbon dioxide (CO2) concentrations have risen to 390 parts per million volume (ppmv), about 40% above pre-Industrial Age concentrations of 280 ppmv and nearly twice those of the last glacial maximum about 22,000 years ago. Similar historical increases are recorded in atmospheric methane (CH4) and nitrous oxide (N2O). There is general agreement that human activity is largely responsible for these trends. Substantial evidence also suggests that elevated greenhouse gas concentrations are responsible for much of the recent atmospheric and oceanic warming, rising sea level, declining Arctic sea-ice cover, retreating glaciers and small ice caps, decreased mass balance of the Greenland and parts of the Antarctic ice sheets, and decreasing ocean pH (ocean "acidification"). Elevated CO2 concentrations raise concern not only from observations of the climate system, but because feedbacks associated with reduced reflectivity from in land and sea ice, sea level, and land vegetation relatively slowly (centuries or longer) to elevated 2 levels. This means that additional human-induced climate change is expected even if the rate of CO2 emissions is reduced or concentrations immediately stabilized.

  2. Andean uplift and climate evolution in the southern Atacama Desert deduced from geomorphology and supergene alunite-group minerals

    NASA Astrophysics Data System (ADS)

    Bissig, Thomas; Riquelme, Rodrigo

    2010-11-01

    Supergene alunite group minerals from the Late Eocene El Salvador porphyry Cu district, the El Hueso epithermal gold deposit and the Coya porphyry Au prospect located in the Precordillera of Northern Chile (~ 26 to 26° 30´ Lat. S) have been dated by the 40Ar/ 39Ar method and analyzed for stable isotopes. These data support published geomorphologic and sedimentologic evidence suggesting that the Precordillera in the Southern Atacama Desert had been uplifted as early as the late Eocene and, thus, significantly prior to the Altiplano which attained its high elevation only in the late Miocene. The oldest supergene alunite from the Damiana exotic deposit at El Salvador was dated at 35.8 ± 1 Ma and yielded a δD (VSMOW) value of -74‰ which indicates elevations of the Precordillera near El Salvador of at least 3000 m in the Late Eocene. In contrast, Miocene supergene alunite from El Salvador, El Hueso, and Coya have less negative δD signatures reaching values as high as -23 to -25‰ at El Hueso and El Salvador between about 8.2 and 14 Ma. Late Miocene to Holocene supergene alunite, jarosite and natroalunite ages are restricted to El Hueso and Coya located near 4000 m above sea level in the Precordillera, roughly 1000 m higher than the present elevation of El Salvador. The δD values of samples younger than ~ 5 Ma vary between -57 and -97‰. The complex evolution of the δD signatures suggests that meteoric waters recorded in supergene alunite group minerals were variably affected by evaporation and provides evidence for climate desiccation and onset of hyper arid conditions in the Central Depression of the southern Atacama Desert after 15 Ma, which agrees well with published constraints from the Atacama Desert at 23-24° Lat. S. Our data also suggest that wetter climatic conditions than at present prevailed in the latest Miocene and early Pliocene in the Precordillera. The new and previously published age constraints for El Salvador indicate that supergene

  3. The fluvial record of climate change.

    PubMed

    Macklin, M G; Lewin, J; Woodward, J C

    2012-05-13

    Fluvial landforms and sediments can be used to reconstruct past hydrological conditions over different time scales once allowance has been made for tectonic, base-level and human complications. Field stratigraphic evidence is explored here at three time scales: the later Pleistocene, the Holocene, and the historical and instrumental period. New data from a range of field studies demonstrate that Croll-Milankovitch forcing, Dansgaard-Oeschger and Heinrich events, enhanced monsoon circulation, millennial- to centennial-scale climate variability within the Holocene (probably associated with solar forcing and deep ocean circulation) and flood-event variability in recent centuries can all be discerned in the fluvial record. Although very significant advances have been made in river system and climate change research in recent years, the potential of fluvial palaeohydrology has yet to be fully realized, to the detriment of climatology, public health, resource management and river engineering. PMID:22474679

  4. Climatic Teleconnections Recorded By Tropical Mountain Glaciers

    NASA Astrophysics Data System (ADS)

    Thompson, L. G.; Permana, D.; Mosley-Thompson, E.; Davis, M. E.

    2014-12-01

    Information from ice cores from the world's highest mountains in the Tropics demonstrates both local climate variability and a high degree of teleconnectivity across the Pacific basin. Here we examine recently recovered ice core records from glaciers near Puncak Jaya in Papua, Indonesia, which lie on the highest peak between the Himalayas and the South American Andes. These glaciers are located on the western side of the Tropical Pacific warm pool, which is the "center of action" for interannual climate variability dominated by El Niño-Southern Oscillation (ENSO). ENSO either directly or indirectly affects most regions of Earth and their populations. In 2010, two ice cores measuring 32.13 m and 31.25 m were recovered to bedrock from the East Northwall Firn ice field. Both have been analyzed in high resolution (~3 cm sample length, 1156 and 1606 samples, respectively) for stable isotopes, dust, major ions and tritium concentrations. To better understand the controls on the oxygen isotopic (δ18 O) signal for this region, daily rainfall samples were collected between January 2013 and February 2014 at five weather stations over a distance of ~90 km ranging from 9 meters above sea level (masl) on the southern coast up to 3945 masl. The calculated isotopic lapse rate for this region is 0.24 ‰/100m. Papua, Indonesian ice core records are compared to ice core records from Dasuopu Glacier in the central Himalayas and from Quelccaya, Huascarán, Hualcán and Coropuna ice fields in the tropical Andes of Peru on the eastern side of the Pacific Ocean. The composite of the annual isotopic time series from these cores is significantly (R2 =0.53) related to tropical Pacific sea surface temperatures (SSTs), reflecting the strong linkage between tropical Pacific SSTs associated with ENSO and tropospheric temperatures in the low latitudes. New data on the already well-documented concomitant loss of ice on Quelccaya, Kilimanjaro in eastern Africa and the ice fields near Puncak

  5. NOAA Climate Data Records Access for Applications

    NASA Astrophysics Data System (ADS)

    Stachniewicz, J. S.; Cecil, D.; Hollingshead, A.; Newport, B. J.; Wunder, D.

    2015-12-01

    There are many potential uses of NOAA Climate Data Records (CDRs) for decision-making and catastrophic risk management assessment activities in the federal, state, and local government and private sectors, in addition to their traditional uses by the academic/scientific community. There is growing interest in using NOAA CDRs for such applications and straightforward access to the data is essential if these applications are to be successful. User engagement activities determine the types of data that users need, as well as the spatial and temporal subsets. This talk will present the access methods currently available and in development. Alternate representations and sources of some CDRs will also be discussed. Recent improvements include: 1. CDR information web page 2. Dataset types, sizes, growth, latency, grid/swath 3. Dataset discovery, data access, and sub-setting. 4. Knowing our users and their needs. 5. Known uses of some CDRs. 6. Migration to CLASS. 7. Other representations - GeoTIFF, Obs4MIPS 8. Cloud applications - Google, Microsoft

  6. Sustained production of multi-decadal climate records - Lessons from the NOAA Climate Data Record Program

    NASA Astrophysics Data System (ADS)

    Bates, J. J.

    2015-12-01

    NOAA's Climate Data Record (CDR) Program was designed to be responsive to the needs of climate monitoring, research, and services with the ultimate aim of serving decision making across a spectrum of users for the long term. It requires the sustained production of high quality, multidecadal time series data describing the global atmosphere, oceans, and land surface that can be used for informed decision making. The challenges of a long-term program of sustaining CDRs, as contrasted with short-term efforts of traditional three-year research programs, are substantial and different. The sustained production of CDRs requires collaboration between experts in the climate community, data management, and software development and maintenance. It is also informed by scientific application and associated user feedback on the accessibility and usability of the produced CDRs. The CDR Program has developed a metric for assessing the maturity of CDRs with respect to data management, software, and user application and applied it to over 28 CDRs. The main/primary lesson learned over the past seven years is that a rigorous, team approach to data management, employing subject matter experts at every step, is critical to open and transparent production. This approach also makes it much easier to support the needs of users who want near-real-time production of "interim" CDRs for monitoring and users who want to use CDRs for tailored authoritative information, such as a drought index. This talk will review of the history of the CDR program, current status, and plans.

  7. An Improved Total Solar Irradiance Climate Data Record

    NASA Astrophysics Data System (ADS)

    Kopp, G.

    2011-12-01

    The dominant driver of the Earth's climate system is the Sun, which exceeds all other energy sources combined by a factor of 2500. Small as they are, variations in the enormous amount of energy received from the Sun can have climatic effects on the Earth over annual to millennial time scales. Climate studies rely on recent spaceborne measurements of total solar irradiance (TSI) and estimates of its historical variability to discern natural from anthropogenic climatic influences. Because the Sun is relatively stable, the TSI measurements providing this solar record must be of high accuracy, extremely good stability, and long duration. New instrument calibrations and diagnostics have improved the accuracy of the existing record and future instruments promise further improvements. I will discuss the status of the current solar climate data record based on recent findings, explain the climate-driven solar irradiance measurement requirements, show estimates of solar influences on climate, and give an overview of planned missions to provide this needed record for climate studies.

  8. Untangling climatic and autogenic signals in peat records

    NASA Astrophysics Data System (ADS)

    Morris, Paul J.; Baird, Andrew J.; Young, Dylan M.; Swindles, Graeme T.

    2016-04-01

    Raised bogs contain potentially valuable information about Holocene climate change. However, autogenic processes may disconnect peatland hydrological behaviour from climate, and overwrite and degrade climatic signals in peat records. How can genuine climate signals be separated from autogenic changes? What level of detail of climatic information should we expect to be able to recover from peat-based reconstructions? We used an updated version of the DigiBog model to simulate peatland development and response to reconstructed Holocene rainfall and temperature reconstructions. The model represents key processes that are influential in peatland development and climate signal preservation, and includes a network of feedbacks between peat accumulation, decomposition, hydraulic structure and hydrological processes. It also incorporates the effects of temperature upon evapotranspiration, plant (litter) productivity and peat decomposition. Negative feedbacks in the model cause simulated water-table depths and peat humification records to exhibit homeostatic recovery from prescribed changes in rainfall, chiefly through changes in drainage. However, the simulated bogs show less resilience to changes in temperature, which cause lasting alterations to peatland structure and function and may therefore be more readily detectable in peat records. The network of feedbacks represented in DigiBog also provide both high- and low-pass filters for climatic information, meaning that the fidelity with which climate signals are preserved in simulated peatlands is determined by both the magnitude and the rate of climate change. Large-magnitude climatic events of an intermediate frequency (i.e., multi-decadal to centennial) are best preserved in the simulated bogs. We found that simulated humification records are further degraded by a phenomenon known as secondary decomposition. Decomposition signals are consistently offset from the climatic events that generate them, and decomposition

  9. Sustained Satellite Missions for Climate Data Records

    NASA Technical Reports Server (NTRS)

    Halpern, David

    2012-01-01

    Satellite CDRs possess the accuracy, longevity, and stability for sustained moni toring of critical variables to enhance understanding of the global integrated Earth system and predict future conditions. center dot Satellite CDRs are a critical element of a global climate observing system. center dot Satellite CDRs are a difficult challenge and require high - level managerial commitment, extensive intellectual capital, and adequate funding.

  10. A Record of Antarctic Climate and Ice Sheet History Recovered

    NASA Astrophysics Data System (ADS)

    Naish, Tim; Powell, Ross; Levy, Richard; Florindo, Fabio; Harwood, David; Kuhn, Gerhard; Niessen, Frank; Talarico, Franco; Wilson, Gary

    2007-12-01

    Antarctica's late Cenozoic (the past ~15 million years) climate history is poorly known from direct evidence, owing to its remoteness, an extensive sea ice apron, and an ice sheet cover over the region for the past 34 million years. Consequently, knowledge about the role of Antarctica's ice sheets in global sea level and climate has relied heavily upon interpretations of oxygen isotope records from deep-sea cores. Whereas these isotopic records have revolutionized our understanding of climate-ice-ocean interactions, questions still remain about the specific role of Antarctic ice sheets in global climate. Such questions can be addressed from geological records at the marine margin of the ice sheets, recovered by drilling from floating ice platforms [e.g., Davey et al., 2001; Harwood et al., 2006; Barrett, 2007].

  11. The geologic record of climatic change

    NASA Technical Reports Server (NTRS)

    Crowley, T. J.

    1982-01-01

    Major results from paleoclimatic investigations are investigated, and background material is included. The time interval surveyed extends from the formation of the Earth 4.6 billion years ago to the development of the instrumental record.

  12. The paleoclimate record of long-term climate variability

    SciTech Connect

    Webb, R.S.; Bartlein, P.J.; Overpeck, J.T. Univ. of Oregon, Eugene )

    1993-06-01

    Climate variability occurs on time scales ranging from decades or shorter to millions of years. An important step in determining the effects of trace-gas-induced warming on climate variability and ecosystems is characterizing past natural variability and change. Throughout the Quaternary long-term climate variability has been dominated by Milankovitch forcing of glacial/interglacial cycles. Superimposed on this millennia-scale orbitally forced variability have been more rapid climate events (e.g. Younger Dryas, Little Ice Age, Medieval Warm Period, Sahelian droughts). Although highly relevant to understanding possible responses of ecosystems to future climate change, most decade to century scale climate variability remains poorly understood. Insights into mechanisms and responses can be obtained from tree rings, ice cores, corals, marine, lake and fluvial sediments, pollen, and macrofossils. These paleoclimate records reveal that the range of natural climate variability is much larger than indicated by the instrumental record of the past 150 years. Global networks of well-dated, high-resolution paleocrunate records for key intervals of the past are currently being assembled. These networks should provide the baseline of natural variability required to understand climate-ecosystem dynamics and to identify anthropogenic-induced change.

  13. Synoptic messages to extend climate data records

    NASA Astrophysics Data System (ADS)

    den Besselaar, E. J. M.; Klein Tank, A. M. G.; Schrier, G.; Jones, P. D.

    2012-04-01

    Synoptic messages (SYNOP) exchanged internationally for operational weather forecasting are regularly used to extend validated (quality controlled) daily climate time series to the present day, despite differences in measuring intervals and lack of validation. Here we focus on the effect of this on derived climate indices of extremes in Europe. Validated time series are taken from the European Climate Assessment & Dataset (ECA&D). Validated data and SYNOP over the period 01 April 1982 to 31 December 2004 are compared. The distribution of the difference series of validated data and SYNOP is skewed. Generally, minimum temperatures are lower or equal in the validated series, while maximum temperatures are higher or equal. This is at least partly due to the 24-hour (validated data) versus 12-hour (SYNOP) measuring intervals. The precipitation results are dependent on the difference between the measuring intervals of both time series. Time series of indices of extremes exhibit a non-climatic inhomogeneity for several indices when SYNOP are used to extend the validated series, leading to spurious trends. The sizes of the trends in pure validated and pure SYNOP series are generally in good agreement, but the absolute values of the indices show an offset. Accepting a trend error of 10%, the averaged winter minimum and maximum temperature and the number of tropical nights (minimum temperature >20°C) in summer allow only a very small fraction of SYNOP in the extended series (about 5-10%), while for the other indices studied here a larger fraction can be used (up to 50%).

  14. A Terrestrial Surface Climate Data Record for Global Change Studies

    NASA Astrophysics Data System (ADS)

    Vermote, E.; Justice, C.; Csiszar, I. A.; Meyer, D. J.; Myneni, R. B.; Baret, F.; Masuoka, E.; Wolfe, R. E.

    2011-12-01

    The overall objective of this project is to produce, validate and distribute a global land surface climate data record (CDR) using a combination of mature and tested algorithms and the best available land imaging polar orbiting satellite data from the past to the present (1981-2011), and which will be extendable into the JPSS era. The data record consists of one fundamental climate data record (FCDR), the surface reflectance product. Two Thematic CDRs (TCDRs) are also be derived from the FCDR, the normalized difference vegetation index (NDVI) and LAI/fAPAR. These two products are used extensively for climate change research and are listed as Essential Climate Variables (ECVs) by the Global Climate Observing System (GCOS). In addition, these products are used in a number of applications of long-term societal benefit. The two TCDRs are used to assess the performance of the FCDR through a rigorous validation program and will provide feedback on the requirements for the Surface Reflectance FCDR. We will focus this presentation on the progress made so far, a discussion of the performance of the version 3.0 (released April 2010) and the subsequent improvements and schedule for release of version 4.0. We will also present in detail the mechanisms for applying peer-reviewed algorithms, product generation, distribution, quality control, uncertainties assessment and metadata standards for this Terrestrial Climate Data Record.

  15. A Terrestrial Surface Climate Data Record for Global Change Studies

    NASA Astrophysics Data System (ADS)

    Vermote, E.; Justice, C. O.; Claverie, M.; Csiszar, I. A.; Meyer, D. J.; Myneni, R.; Baret, F.; Masuoka, E.; Wolfe, R. E.

    2012-12-01

    This paper presents results from a project to produce, validate and distribute a global land surface Climate Data Record (CDR) using a combination of mature and tested algorithms and the best available polar orbiting satellite data from the past to the present (1981-2012), which can be extendable into the JPSS era. The data record consists of one fundamental climate data record (FCDR), the surface reflectance product. Two Thematic CDRs (TCDRs) are also be derived from the FCDR, the normalized difference vegetation index (VI) and LAI/fAPAR. These two products are used extensively for climate change research and are listed as Essential Climate Variables (ECVs) by the Global Climate Observing System (GCOS). In addition, these products are used in a number of applications of long-term societal benefit. The two TCDRs are used to assess the performance of the FCDR through a rigorous validation program and will provide feedback on the requirements for the Surface Reflectance FCDR. We will focus in this presentation on the progress made so far, the discussion of the performance of version 3.0 of the product and the subsequent improvements and schedule for release of version 4.0. We will also present in detail the mechanisms for product generation, distribution, quality control, uncertainties assessment for this Terrestrial Climate Data Record. We will finally present practical applications of this dataset to forest cover change detection over the long term as well as drought monitoring in the context of agricultural production and food security.

  16. Climatic change and permafrost. Record from surficial deposits

    USGS Publications Warehouse

    Carter, L. David

    1990-01-01

    The physical and chemical characteristics of surficial deposits and the floral and faunal remains they contain provide information that is useful for interpreting both paleoclimatic and past permafrost conditions. Surficial deposits thus provide a record of climatic change and permafrost history. This record suggests that initiation of permafrost in lowland areas of the Southern Arctic Archipelago and continents of the northern hemisphere may have occurred about 2,400,000 years ago during the pronounced cooling that led to the first major glaciation of late Cenozoic time. Since then, climate has been relatively cold but cyclically variable, characterized by the growth and shrinkage of large, continental ice sheets. Permafrost has expanded and contracted in response to these climatic changes, and we can expect the present permafrost conditions to change in response to future climatic changes. To predict the response of permafrost and the landscape to future climatic change we should: (1) Define relations between climate and the modern landscape; (2) establish long-term records of past climatic change and landscape response; and (3) determine the paleoenvironments of past warm periods as possible analogs for future global warming.

  17. Interpretation of our present terrestrial climatic record

    SciTech Connect

    Ellsaesser, H.W.

    1987-09-01

    Detailed studies of profiles of delta/sup 18/O in oceanic and glacial cores and of pollen deposits in bogs indicate that the terrestrial climatic system, consisting of the atmosphere, hydrosphere, lithosphere and biosphere, is capable of oscillations with amplitudes, such as that of the Melisey II stadial of northern France, approaching or equaling that of the glacial-interglacial cycle but on time scales too short for the usually envisioned transfer of mass between the oceans and continental glaciers. Abrupt oscillations or shifts to new equilibrium are well documented in the Boelling-Aleroed warming and Younger Dryas readvance, the 0.4/sup 0/C rise in NH continental air temperature circa 1920 and the year-to-year oscillations in NH continental air temperatures from 1976 to 1984. Such abrupt oscillations defy explanation in terms of external forcing functions and suggest rather internal rearrangements within the climate system as the driving mechanism. Suggestions are made as to mechanisms for possible internal rearrangements which might lead to different hemispheric or global mean surface temperatures.

  18. NSIDC Contributions to Cryospheric Climate Data Records

    NASA Astrophysics Data System (ADS)

    Barry, R. G.; Armstrong, R. L.; Weaver, R. L.

    2008-12-01

    We assess NSIDC holdings as they relate to the development of consistent, calibrated time series - Earth Science Data Records for the cryosphere. Gaps in the documentation of the major cryospheric elements are identified in the Integrated Global Observing Strategy- Partnership (IGOS-P) cryosphere theme report. Filling these gaps will be a focus of the planned World Meteorological Organization's Global Cryosphere Watch (GCW). Snow cover extent from 1966 is the longest satellite record, and this data product is available from NSIDC as the Northern Hemisphere EASE-Grid Weekly Snow Cover and Sea Ice Extent Version 3. The main gap in snow cover data is the absence in freely accessible archives of station snow depths, especially for European countries.. There is no uniformly reliable data set of in situ snow water equivalent although since 1979 global products from passive microwave satellite data are available from NSIDC as the Global EASE-Grid Monthly Snow Water Equivalent Climatology Product . Corresponding data on global sea ice extent and concentration are also available from 1979 and most earlier operational chart products are accessible via the Global Digital Sea Ice Data Base at NSIDC. Snapshots of Arctic ice thickness exist from 1958 to present from submarine and moored upward-looking sonars, although not all of the Arctic Ocean is covered by these data. The World Glacier Inventory lists about 100,000 (two-thirds of all) glaciers but there are major gaps around Greenland and Antarctica, in the Himalayas and the United States. There are outlines (shapefiles and associated metadata) for over 65,000 glaciers in the NSIDC Global Land Ice Measurements from Space (GLIMS) data base and work is underway to complete these databases. However, there are globally only about 30 continuous mass balance records and larger glaciers are poorly represented. There are piecemeal records of lake and river ice in national archives but those available from NSIDC number 748 water

  19. Achieving Global Ocean Color Climate Data Records

    NASA Technical Reports Server (NTRS)

    Franz, Bryan

    2010-01-01

    Ocean color, or the spectral distribution of visible light upwelling from beneath the ocean surface, carries information on the composition and concentration of biological constituents within the water column. The CZCS mission in 1978 demonstrated that quantitative ocean color measurements could be. made from spaceborne sensors, given sufficient corrections for atmospheric effects and a rigorous calibration and validation program. The launch of SeaWiFS in 1997 represents the beginning of NASA's ongoing efforts to develop a continuous ocean color data record with sufficient coverage and fidelity for global change research. Achievements in establishing and maintaining the consistency of the time-series through multiple missions and varying instrument designs will be highlighted in this talk, including measurements from NASA'S MODIS instruments currently flying on the Terra and Aqua platforms, as well as the MERIS sensor flown by ESA and the OCM-2 sensor recently launched by ISRO.

  20. Ice Core Records of Recent Northwest Greenland Climate

    NASA Astrophysics Data System (ADS)

    Osterberg, E. C.; Wong, G. J.; Ferris, D.; Lutz, E.; Howley, J. A.; Kelly, M. A.; Axford, Y.; Hawley, R. L.

    2014-12-01

    Meteorological station data from NW Greenland indicate a 3oC temperature rise since 1990, with most of the warming occurring in fall and winter. According to remote sensing data, the NW Greenland ice sheet (GIS) and coastal ice caps are responding with ice mass loss and margin retreat, but the cryosphere's response to previous climate variability is poorly constrained in this region. We are developing multi-proxy records (lake sediment cores, ice cores, glacial geologic data, glaciological models) of Holocene climate change and cryospheric response in NW Greenland to improve projections of future ice loss and sea level rise in a warming climate. As part of our efforts to develop a millennial-length ice core paleoclimate record from the Thule region, we collected and analyzed snow pit samples and short firn cores (up to 21 m) from the coastal region of the GIS (2Barrel site; 76.9317o N, 63.1467o W, 1685 m el.) and the summit of North Ice Cap (76.938o N, 67.671o W, 1273 m el.) in 2011, 2012 and 2014. The 2Barrel ice core record has statistically significant relationships with regional spring and fall Baffin Bay sea ice extent, summertime temperature, and annual precipitation. Here we evaluate relationships between the 2014 North Ice Cap firn core glaciochemical record and climate variability from regional instrumental stations and reanalysis datasets. We compare the coastal North Ice Cap record to more inland records from 2Barrel, Camp Century and NEEM to evaluate spatial and elevational gradients in recent NW Greenland climate change.

  1. Developing NOAA's Climate Data Records From AVHRR and Other Data

    NASA Astrophysics Data System (ADS)

    Privette, J. L.; Bates, J. J.; Kearns, E. J.

    2010-12-01

    As part of the provisional NOAA Climate Service, NOAA is providing leadership in the development of authoritative, measurement-based information on climate change and variability. NOAA’s National Climatic Data Center (NCDC) recently initiated a satellite Climate Data Record Program (CDRP) to provide sustained and objective climate information derived from meteorological satellite data that NOAA has collected over the past 30+ years - particularly from its Polar Orbiting Environmental Satellites (POES) program. These are the longest sustained global measurement records in the world and represent billions of dollars of investment. NOAA is now applying advanced analysis methods -- which have improved remarkably over the last decade -- to the POES AVHRR and other instrument data. Data from other satellite programs, including NASA and international research programs and the Defense Meteorological Satellite Program (DMSP), are also being used. This process will unravel the underlying climate trend and variability information and return new value from the records. In parallel, NCDC will extend these records by applying the same methods to present-day and future satellite measurements, including the Joint Polar Satellite System (JPSS) and Jason-3. In this presentation, we will describe the AVHRR-related algorithm development activities that CDRP recently selected and funded through open competitions. We will particularly discuss some of the technical challenges related to adapting and using AVHRR algorithms with the VIIRS data that should become available with the launch of the NPOESS Preparatory Project (NPP) satellite in early 2012. We will also describe IT system development activities that will provide data processing and reprocessing, storage and management. We will also outline the maturing Program framework, including the strategies for coding and development standards, community reviews, independent program oversight, and research-to-operations algorithm

  2. Identifying climate change threats to the arctic archaeological record

    NASA Astrophysics Data System (ADS)

    Murray, Maribeth; Jensen, Anne; Friesen, Max

    2011-05-01

    Global Climate Change and the Polar Archaeological Record; Tromsø, Norway, 15-16 February 2011 ; A workshop was held at the Institute of Archaeology and Social Anthropology, University of Tromsø, in Norway, to catalyze growing concern among polar archaeologists about global climate change and attendant threats to the polar archaeological and paleoecological records. Arctic archaeological sites contain an irreplaceable record of the histories of the many societies that have lived in the region over past millennia. Associated paleoecological deposits provide powerful proxy evidence for paleoclimate and ecosystem structure and function and direct evidence of species diversity, distributions, and genetic variability. Archaeological records can span most of the Holocene (the past ∼12,000 years), depending upon location, and paleoecological records extend even further. Most are largely unstudied, and, although extremely vulnerable to destruction, they are poorly monitored and not well protected. Yet these records are key to understanding how the Arctic has functioned as a system, how humans were integrated into it, and how humans may have shaped it. Such records provide a wide range of data that are not obtainable from sources such as ice and ocean cores; these data are needed for understanding the past, assessing current and projecting future conditions, and adapting to ongoing change.

  3. Late Pliocene-Quaternary humidity fluctuations on the NE Tibetan Plateau deduced from the magnetic record in lacustrine sediments of the Qaidam paleolake (Invited)

    NASA Astrophysics Data System (ADS)

    Herb, C.; Zhang, W.; Appel, E.; Koutsodendris, A.; Pross, J.; Fang, X.

    2013-12-01

    The Qaidam Basin on the NE fringe of the Tibetan Plateau is well-suited for studying past environmental changes as it contains a thick sediment sequence that was deposited almost continuously since the Eocene. The deep drilling core SG-1 (~940-m-long) from the Chahansilatu sub-basin in the western part of the Qaidam Basin offers a time span from 2.8 Ma to the complete drying of the lake near the drilling location at ~0.1 Ma (average sedimentation rate 35.1 cm/kyr). The presently hyper-arid Qaidam Basin is located in the area of influence of the Westerlies and may have been reached by the East Asian and possible even the Indian monsoon in the past. The integrated observation of several magnetic proxies recorded in drill core SG-1 allows detecting magnetic susceptibility (χ) as a useful high-resolution (~1 ka) climate proxy with supporting information from other parameters. Long-term trends of χ can be attributed to changing lake levels inferred from the comparison to lithological studies of SG-1 and to local tectonic activity. Short-term cyclic variation of χ, which exceed the magnitude of the long-term shift, can be correlated to marine oxygen isotope records. Spectral analysis suggests that the χ variation contains a response to orbital forcing. The cyclic χ variation can be attributed to a mixture between (i) low-temperature oxidation (LTO) in the catchment area and (ii) a change of the catchment area during past times. LTO in the catchment implies strong weathering and accordingly higher lake levels in times of low χ values and vice versa. In contrast, a spatial change of the catchment area points to more humid times with prevailing surface erosion in lower elevations accompanied by sediment supply with higher χ values. We compared the magnetic signature to palynological results in order to confirm the link between χ in the lacustrine sediments of drill core SG-1 and past environmental changes and to use lows and highs of χ for high

  4. Transition of SSMI Data to a Climate Data Record

    NASA Astrophysics Data System (ADS)

    Semunegus, H.; Bates, J. J.

    2007-12-01

    Since 1993, the National Oceanic and Atmospheric Administration's (NOAA) National Climatic Data Center (NCDC) has served as the active archive of passive microwave satellite measurements from the Defense Meteorological Satellite Program's (DMSP) Special Sensor Microwave Imager (SSMI) instrument. SSMI data measurements have been used extensively to generate climate data sets (including rain, snow, ice, cloud liquid water, and total precipitable water) in support of both national and international programs. A project by NCDC and NOAA's Center for Satellite Applications and Research (STAR) is working towards the goal of regenerating a high quality SSMI Climate Data Record as defined by NOAA's Scientific Data Stewardship (SDS) program. As part of this effort, the SSMI Temperature Data Record (TDR) and Sensor Data Record (SDR) datasets have been reprocessed as value-added network Common Data Form (netCDF) orbit files. Data quality control flags embedded in netCDF orbit files preserve the original data, while warning users of erroneous geolocation, radiance and temporal values at the pixel level. These orbit files will also extend the period of record of SSMI data publicly available at NOAA's Comprehensive Large-Array Stewardship System (CLASS) by several years (August 1993-February 1997). Making earlier SSMI data available to customers and improving the quality of the SSMI dataset are important steps in attaining higher levels of dataset maturity in terms of scientific value and data preservation.

  5. METEOSAT IR and WV channels Fundamental Climate Data Record

    NASA Astrophysics Data System (ADS)

    Roebeling, Rob; John, Viju; Hewison, Tim; Lattanzio, Alessio; Schulz, Joerg

    2015-04-01

    The detection of climate change and analysis of climate variability at inter-annual scales requires long-term, well calibrated observations that are homogenised in time and space. Observations from EUMETSAT's series of Meteosat First Generation (MFG) and Meteosat Second Generation (MSG) geostationary satellites span a period from 1982 to today. Although these satellites provide data for climate analysis at multi-decadal scales, their applicability for such analysis is hampered by heterogeneities in the time series due to successive radiometers having different filter functions and changes in the calibration methodology. EUMETSAT initiated the activity to improve the quality of these data, and generates a Fundamental Climate Data Record (FCDR) of Water Vapour (WV) and Infrared (IR) channel radiances, i.e., a long-term data record of calibrated and quality-controlled sensor data designed to allow the generation of homogeneous products that are accurate and stable enough for climate monitoring. The generation of this FCDR is part of EUMETSATs activities in the European Re-Analysis of global CLIMate observations 2 (ERA-CLIM2) project. We present a method to inter-calibrate the complete time series of WV (6.3 µm) and IR (11.8 µm) channel radiances from MFG-MVIRI and MSG-SEVIRI observations. Our method is based on the principles of the Global Space-based Inter-Calibration System (GSICS). A systematic review of spectral conversion functions, which often dominate the errors, indicates that spectral changes of the WV channel from HIRS/2 to HIRS/3 triples the uncertainty of inter-calibrated METEOSAT WV radiances. We will show that these issues can be circumvented by using HIRS/2, AIRS, and IASI as reference instruments, and thus keeping the uncertainties due to spectral conversion similar throughout the time series. Finally we will present an evaluation of 30 years of recalibrated HIRS, MVIRI and /SEVIRI radiances from the IR and WV channels, and demonstrate their improved

  6. Canada's Landscape Response To Climate Change From Satellite Records

    NASA Astrophysics Data System (ADS)

    Latifovic, R.; Trishchenko, A.; Pouliot, D.

    2005-12-01

    Progress towards sustainability, including adaptation to climate change relies on our ability to monitor and predict impacts on the environment resulting from combined human and natural causes. The synthesis of current knowledge and quantitative impact assessments used by stakeholders and decision makers regarding climate change are founded on observations sustained over decades. Such long-term observations of the earth's surface and atmospheric properties can be provided to a large degree by earth observation systems. Satellite data contain valuable measurements of sufficient length and continuity to generate geophysical time series of land cover, leaf area index, cloud fraction, albedo, radiation, lake temperature and other land, atmosphere and water properties. In addition to studying climate change the information provided by such data, can be used in wide range of applications related to natural resource development, agriculture, environmental monitoring, and ocean surveillance. In response to this recognized need, under the project National Action on Climate Change in the framework of the Climate Change Program of Natural Resources Canada the generation of a comprehensive satellite data record has been initiated. The new archive includes AVHRR data at 1-km spatial resolution over Canada for 1985-2004 (20 years), SPOT/VGT 1&2 (1998-2004) and MODIS (2000-2005). The first evaluation of landscape response to global climate change at regional level using the new archive will be presented through examples related to land cover change, landscape productivity, and lake and sea ice variability.

  7. Use of Paleomagnetic Secular Variation, Excursion, and Reversal Records to Correlate African Lake Climate Records

    NASA Astrophysics Data System (ADS)

    King, J.; Heil, C.; Peck, J.; Scholz, C.; Shanahan, T.; Overpeck, J.

    2005-12-01

    Geomagnetic secular variation, excursions, and reversal records can provide an excellent means for high resolution correlation of sedimentary climate records. Recent drilling projects on Lake Bosumtwi, Ghana, and Lake Malawi, Malawi, have provided the opportunity to study long African climate records (<1 Ma). Magnetic studies of these sedimentary archives indicate that high quality SV records are preserved through most of the sequence despite the fact that anoxia is the usual condition of bottom waters in both lakes. We compare the magnetic records of Lake Bosumtwi and Lake Malawi to test our ability to correlate between West African and East African lakes. In addition, we compare the magnetic record of Lake Malawi to records from Lake Tanganyika in East Africa and the Indian Ocean region, and the record of Lake Bosumtwi to that of Lake Barombi Mbo in West Africa. Correlations within regions are straightforward and highly useful for intrasite correlation. Correlation between East and West Africa is also possible, although the resolution of the correlation is more limited.

  8. A long-term climate data record of scatterometer winds

    NASA Astrophysics Data System (ADS)

    Belmonte Rivas, Maria; Stoffelen, Ad; Verhoef, Anton; de Kloe, Jos; Verspeek, Jeroen; Vogelzang, Jur

    2015-04-01

    The ocean surface wind stress is a key element of the air-sea interaction, which refers to the transfer of energy, momentum and trace gases between the ocean and the atmosphere, both essential components of the Earth's climate system. We propose to create a global and continuous climate data record (CDR) of ocean stress-equivalent winds from satellite scatterometers from 1991 to present date. This will be done by reprocessing the entire backscatter archives from the ERS1 and ERS2, Quikscat SeaWinds, Metop-A ASCAT and Oceansat-2 OSCAT instruments using publicly available wind retrieval packages and special emphasis on sensor inter-calibration. Along with a consistent long-term record of scatterometer wind stress, this CDR will deliver wind curl/divergence and sea ice extents. This contribution reports on progress made, applications envisioned and current status of this activity.

  9. Biomarker records of Holocene climate variations in Asian interior

    NASA Astrophysics Data System (ADS)

    Song, M.; Liu, Z.; Liu, W.; Zhao, C.; Li, S.; He, Y.

    2012-12-01

    Understanding Holocene climate fluctuation may provide clues to projection of future climate change. Lake sediments in the arid central Asia (ACA), as an archive of past climate information, keep attracting considerable interest. We have retrieved several sediment cores from Lake Manas, an endorheic lake in Zunggar desert, Xinjiang Province, China. Biomarker proxies including alkenone Uk'37, %C37:4 and C37 concentration (C37 Conc), and physical proxies including density and magnetic susceptibility (MS) have been analyzed. We have found substantial climatic and environmental changes during the late Holocene. Density, MS and Uk'37 values are high during Medieval Warm Period (MWP) and C37 Conc is very low. During the Little Ice Age, density and MS decrease, Uk'37 values drop to near 0.1, C37 Conc is increased by 2 to 3 magnitude. Thus, warm and dry conditions dominated MWP while cold and wet conditions dominated LIA, a typical "Westerly" pattern which is opposite to the hydrological variation in Asian monsoonal regions. Biomarker records' correlation with solar irradiance (SI), the North Atlantic Oscillation (NAO), the 1000year ACA Moisture Index (ACAM), and the North Hemisphere Temperature (NHT) suggests SI as one of the forcing factor on temperature fluctuation and cold and wet LIA possibly resulting from westerly-jet shift, negative NAO oscillation and the lower evaporation induced by the decrease of temperature. Biomarker records for the whole Holocene will be also presented.

  10. Progress and Processes for Generating NOAA's Climate Data Records

    NASA Astrophysics Data System (ADS)

    Johnston, S. S.; Glance, W. J.; Bates, J. J.; Kearns, E. J.

    2011-12-01

    NOAA established a satellite Climate Data Record Program (CDRP) at its National Climatic Data Center (NCDC) to provide a systematic reprocessing capability which will generate sustained and authoritative climate information from 30+ years of satellite data. CDRP implements a unique approach in archiving not only the data products themselves, but also the software, ancillary data, and enough documentation to allow any user with the processing power, to reproduce the data. Best practices, such as a common maturity matrix, software guidelines, and format standards, are employed to facilitate both the transition of research algorithms to operational software, and the long-term maintenance of the software. Throughout the implementation and execution of the program, CDRP seeks to adhere to production guidelines from Global Climate Observing System (GCOS) and World Meteorological Organization's (WMO's) Sustained, Coordinated Processing of Environmental Satellite Data for Climate Monitoring (SCOPE-CM activity. Elements of the CDR Adaptive Processing System (CAPS) are described, along with the system's implementation approach, performance expectations, and plans for growth to accommodate increased CDR processing. In addition, a cost model has been implemented to capture the cost of CDR generation and maintenance, considering variables such as CDR complexity, source, and maturity at the beginning of the process.

  11. Climatic records over the past 30 ka from temperate Australia - a synthesis from the Oz-INTIMATE workgroup

    NASA Astrophysics Data System (ADS)

    Petherick, L.; Bostock, H.; Cohen, T. J.; Fitzsimmons, K.; Tibby, J.; Fletcher, M.-S.; Moss, P.; Reeves, J.; Mooney, S.; Barrows, T.; Kemp, J.; Jansen, J.; Nanson, G.; Dosseto, A.

    2013-08-01

    Temperate Australia sits between the heat engine of the tropics and the cold Southern Ocean, encompassing a range of rainfall regimes and falling under the influence of different climatic drivers. Despite this heterogeneity, broad-scale trends in climatic and environmental change are evident over the past 30 ka. During the early glacial period (˜30-22 ka) and the Last Glacial Maximum (˜22-18 ka), climate was relatively cool across the entire temperate zone and there was an expansion of grasslands and increased fluvial activity in regionally important Murray-Darling Basin. The temperate region at this time appears to be dominated by expanded sea ice in the Southern Ocean forcing a northerly shift in the position of the oceanic fronts and a concomitant influx of cold water along the southeast (including Tasmania) and southwest Australian coasts. The deglacial period (˜18-12 ka) was characterised by glacial recession and eventual disappearance resulting from an increase in temperature deduced from terrestrial records, while there is some evidence for climatic reversals (e.g. the Antarctic Cold Reversal) in high resolution marine sediment cores through this period. The high spatial density of Holocene terrestrial records reveals an overall expansion of sclerophyll woodland and rainforest taxa across the temperate region after ˜12 ka, presumably in response to increasing temperature, while hydrological records reveal spatially heterogeneous hydro-climatic trends. Patterns after ˜6 ka suggest higher frequency climatic variability that possibly reflects the onset of large scale climate variability caused by the El Niño/Southern Oscillation.

  12. Antarctic climate signature in the Greenland ice core record

    PubMed Central

    Barker, Stephen; Knorr, Gregor

    2007-01-01

    A numerical algorithm is applied to the Greenland Ice Sheet Project 2 (GISP2) dust record from Greenland to remove the abrupt changes in dust flux associated with the Dansgaard–Oeschger (D–O) oscillations of the last glacial period. The procedure is based on the assumption that the rapid changes in dust are associated with large-scale changes in atmospheric transport and implies that D–O oscillations (in terms of their atmospheric imprint) are more symmetric in form than can be inferred from Greenland temperature records. After removal of the abrupt shifts the residual, dejumped dust record is found to match Antarctic climate variability with a temporal lag of several hundred years. It is argued that such variability may reflect changes in the source region of Greenland dust (thought to be the deserts of eastern Asia). Other records from this region and more globally also reveal Antarctic-style variability and suggest that this signal is globally pervasive. This provides the potential basis for suggesting a more important role for gradual changes in triggering more abrupt transitions in the climate system. PMID:17954910

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

    PubMed

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

    2016-01-01

    The driving force behind Quaternary glacial-interglacial cycles and much associated climate change is widely considered to be orbital forcing. However, previous versions of the iconic Devils Hole (Nevada) subaqueous calcite record exhibit shifts to interglacial values ~10,000 years before orbitally forced ice age terminations, and interglacial durations ~10,000 years longer than other estimates. Our measurements from Devils Hole 2 replicate virtually all aspects of the past 204,000 years of earlier records, except for the timing during terminations, and they lower the age of the record near Termination II by ~8000 years, removing both ~10,000-year anomalies. The shift to interglacial values now broadly coincides with the rise in boreal summer insolation, the marine termination, and the rise in atmospheric CO2, which is consistent with mechanisms ultimately tied to orbital forcing. PMID:26744404

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

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

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

  15. Developing climate data records and essential climate variables from landsat data

    USGS Publications Warehouse

    Dwyer, John; Dinardo, Thomas P.; Muchoney, Douglas M.

    2011-01-01

    The series of Landsat missions has compiled the longest record of satellite observation of the Earth’s land surface, extending for more than 38 years for most areas of the globe. Landsat data are particularly important as long term climate data records because the scale of observation is sufficient to differentiate between natural and human drivers of land cover change. The USGS has established consistent radiometric calibration across the Landsat TM and ETM+ sensors, and have extended the calibration back to the earlier MSS sensors. The USGS is developing capabilities to create fundamental climate data records (FCDRs), thematic climate data records (TCDRs), and essential climate variables (ECVs) from the Landsat data archive. Two high priority TCDRs were identified: surface reflectance and land surface temperature because they have direct application or are required as input to the generation of ECVs. We will focus development on a few of the terrestrial ECVs that have a high potential for being derived from Landsat data, that include land cover, albedo, fire disturbance, surface water, snow and ice, and leaf area index (LAI). We are collaborating with scientists who have demonstrated successful algorithm development and application of these science products to develop a framework of processing capabilities to support research projects and land management applications, along with an independent strategy for product validation. Our goal is to scale the creation and validation of these products from specific sites in the conterminous U.S. and Alaska, for extension to continental and global scales.

  16. A Holocene climate record from palaeolakes in NW India

    NASA Astrophysics Data System (ADS)

    Dixit, Y.; Hodell, D. A.; Petrie, C.

    2011-12-01

    The plains of NW India encompasses arid, semi-arid to sub-humid zones and archaeological research indicate this region was intensively settled by the Indus Valley Civilization. The precise climatological and environmental history of this region during the Holocene period remain largely unknown. We present high-resolution isotope proxy records of local palaeoclimate change from lacustrine deposits in two different climatic zones from west to east; Palaeo-lake Riwasa in the semi-arid and paleo-lake Kotla Dahar in the sub-humid region in Haryana plains, India. The oxygen isotope record from palaeolake Riwasa indicates the inception of wet climate conditions and establishment of a deep, permanent lake in the basin at ~8870 14C yr BP, coinciding approximately with the early Holocene maximum in the Indian monsoon. A major desiccation event occurs after ~7000 14C yr BP. Our results from palaeolake Riwasa indicate that the permanent deep-water lake and major desiccation event in semi-arid region pre-dated the urban phase of the Indus Civilization. Palaeolake Kotla Dahar is located further east than Riwasa in the sub-humid zone, and receives 500-700mm rainfall. Calcium carbonate percent of bulk sediments from Kotla Dahar increases down section to a maximum of 72%, indicating the presence of a deep carbonate marl lake. Oxygen isotopes are currently being measured on gastropod and ostracod shells and radiocarbon dates are being obtained from this section. We speculate that the oxygen isotope record from Kotla Dahar may provide critical climate data for the period between 5000-3500 BP, the period of Harappan Urbanism. Our study of palaeo-lakes Riwasa and Kotla Dahar constitute the first oxygen isotope records from the plains of NW India to interpret the palaeoclimate history of this region.

  17. Break and trend analysis of EUMETSAT Climate Data Records

    NASA Astrophysics Data System (ADS)

    Doutriaux-Boucher, Marie; Zeder, Joel; Lattanzio, Alessio; Khlystova, Iryna; Graw, Kathrin

    2016-04-01

    EUMETSAT reprocessed imagery acquired by the Spinning Enhanced Visible and Infrared Imager (SEVIRI) on board Meteosat 8-9. The data covers the period from 2004 to 2012. Climate Data Records (CDRs) of atmospheric parameters such as Atmospheric Motion Vectors (AMV) as well as Clear and All Sky Radiances (CSR and ASR) have been generated. Such CDRs are mainly ingested by ECMWF to produce a reanalysis data. In addition, EUMETSAT produced a long CDR (1982-2004) of land surface albedo exploiting imagery acquired by the Meteosat Visible and Infrared Imager (MVIRI) on board Meteosat 2-7. Such CDR is key information in climate analysis and climate models. Extensive validation has been performed for the surface albedo record and a first validation of the winds and clear sky radiances have been done. All validation results demonstrated that the time series of all parameter appear homogeneous at first sight. Statistical science offers a variety of analyses methods that have been applied to further analyse the homogeneity of the CDRs. Many breakpoint analysis techniques depend on the comparison of two time series which incorporates the issue that both may have breakpoints. This paper will present a quantitative and statistical analysis of eventual breakpoints found in the MVIRI and SEVIRI CDRs that includes attribution of breakpoints to changes of instruments and other events in the data series compared. The value of different methods applied will be discussed with suggestions how to further develop this type of analysis for quality evaluation of CDRs.

  18. Antarctic Cenozoic climate history from sedimentary records: ANDRILL and beyond.

    PubMed

    McKay, R M; Barrett, P J; Levy, R S; Naish, T R; Golledge, N R; Pyne, A

    2016-01-28

    Mounting evidence from models and geological data implies that the Antarctic Ice Sheet may behave in an unstable manner and retreat rapidly in response to a warming climate, which is a key factor motivating efforts to improve estimates of Antarctic ice volume contributions to future sea-level rise. Here, we review Antarctic cooling history since peak temperatures of the Middle Eocene Climatic Optimum (approx. 50 Ma) to provide a framework for future initiatives to recover sediment cores from subglacial lakes and sedimentary basins in Antarctica's continental interior. While the existing inventory of cores has yielded important insights into the biotic and climatic evolution of Antarctica, strata have numerous and often lengthy time breaks, providing a framework of 'snapshots' through time. Further cores, and more work on existing cores, are needed to reconcile Antarctic records with the more continuous 'far-field' records documenting the evolution of global ice volume and deep-sea temperature. To achieve this, we argue for an integrated portfolio of drilling and coring missions that encompasses existing methodologies using ship- and sea-ice-/ice-shelf-based drilling platforms as well as recently developed seafloor-based drilling and subglacial access systems. We conclude by reviewing key technological issues that will need to be overcome. PMID:26667911

  19. A speleothem record of Holocene climate variability from southwestern Mexico

    NASA Astrophysics Data System (ADS)

    Bernal, Juan Pablo; Lachniet, Matthew; McCulloch, Malcolm; Mortimer, Graham; Morales, Pedro; Cienfuegos, Edith

    2011-01-01

    A paleoclimate reconstruction for the Holocene based upon variations of δ 18O in a U-Th dated stalagmite from southwestern Mexico is presented. Our results indicate that the arrival of moisture to the area has been strongly linked to the input of glacial meltwaters into the North Atlantic throughout the Holocene. The record also suggests a complex interplay between Caribbean and Pacific moisture sources, modulated by the North Atlantic SST and the position of the ITCZ, where Pacific moisture becomes increasingly more influential through ENSO since ~ 4.3 ka. The interruption of stalagmite growth during the largest climatic anomalies of the Holocene (10.3 and 8.2 ka) is evidenced by the presence of hiatuses, which suggest a severe disruption in the arrival of moisture to the area. The δ 18O record presented here has important implications for understanding the evolution of the North American Monsoon and climate in southwestern Mexico, as it represents one of the most detailed archives of climate variability for the area spanning most of the Holocene.

  20. Evidence for climate change in the satellite cloud record.

    PubMed

    Norris, Joel R; Allen, Robert J; Evan, Amato T; Zelinka, Mark D; O'Dell, Christopher W; Klein, Stephen A

    2016-08-01

    Clouds substantially affect Earth's energy budget by reflecting solar radiation back to space and by restricting emission of thermal radiation to space. They are perhaps the largest uncertainty in our understanding of climate change, owing to disagreement among climate models and observational datasets over what cloud changes have occurred during recent decades and will occur in response to global warming. This is because observational systems originally designed for monitoring weather have lacked sufficient stability to detect cloud changes reliably over decades unless they have been corrected to remove artefacts. Here we show that several independent, empirically corrected satellite records exhibit large-scale patterns of cloud change between the 1980s and the 2000s that are similar to those produced by model simulations of climate with recent historical external radiative forcing. Observed and simulated cloud change patterns are consistent with poleward retreat of mid-latitude storm tracks, expansion of subtropical dry zones, and increasing height of the highest cloud tops at all latitudes. The primary drivers of these cloud changes appear to be increasing greenhouse gas concentrations and a recovery from volcanic radiative cooling. These results indicate that the cloud changes most consistently predicted by global climate models are currently occurring in nature. PMID:27398619

  1. Evidence for climate change in the satellite cloud record

    DOE PAGESBeta

    Norris, Joel R.; Allen, Robert J.; Evan, Amato T.; Zelinka, Mark D.; O'Dell, Christopher W.; Klein, Stephen A.

    2016-07-11

    Clouds substantially affect Earth’s energy budget by reflecting solar radiation back to space and by restricting emission of thermal radiation to space1. They are perhaps the largest uncertainty in our understanding of climate change, owing to disagreement among climate models and observational datasets over what cloud changes have occurred during recent decades and will occur in response to global warming2, 3. This is because observational systems originally designed for monitoring weather have lacked sufficient stability to detect cloud changes reliably over decades unless they have been corrected to remove artefacts4, 5. Here we show that several independent, empirically corrected satellitemore » records exhibit large-scale patterns of cloud change between the 1980s and the 2000s that are similar to those produced by model simulations of climate with recent historical external radiative forcing. Observed and simulated cloud change patterns are consistent with poleward retreat of mid-latitude storm tracks, expansion of subtropical dry zones, and increasing height of the highest cloud tops at all latitudes. The primary drivers of these cloud changes appear to be increasing greenhouse gas concentrations and a recovery from volcanic radiative cooling. Here, these results indicate that the cloud changes most consistently predicted by global climate models are currently occurring in nature.« less

  2. Elements of a Successful Climate Data Records Generation Program

    NASA Astrophysics Data System (ADS)

    Robinson, D. A.

    2005-12-01

    For the past four decades, data flowing from satellite-borne sensors have provided environmental information at spatial scales only dreamed of previously. Remarkable insights have been gained regarding Earth's land, atmosphere, oceans and cryosphere systems. This includes their internal dynamics and kinematics, along with important interrelationships. Additionally, time series of elements within these systems have been scrutinized in attempts to better understand climate variability and to identify critical trends that may signal changes in the climate system. From these studies, has emerged a growing appreciation for the importance of satellite climate data records (CDRs) that possess the accuracy, longevity and stability to facilitate credible climate monitoring. These satellite CDRs provide abundant information to assist those making decisions regarding the fate of our environment. Recently, a National Research Council committee was tasked with assisting the National Oceanic and Atmospheric Administration as it designs a plan to establish this agency as the chief steward of satellite CDRs. Based on an evaluation of historical lessons learned, community surveys, a workshop, and committee expertise, the committee identified 14 key elements for creating a CDR program based mainly on satellites. They are divided into three general categories that include organizational, generation and sustaining elements, many of which are applicable to any CDR endeavor. This presentation will address the 14 elements and provide examples of candidate satellite CDRs.

  3. Evidence for climate change in the satellite cloud record

    NASA Astrophysics Data System (ADS)

    Norris, Joel R.; Allen, Robert J.; Evan, Amato T.; Zelinka, Mark D.; O’Dell, Christopher W.; Klein, Stephen A.

    2016-08-01

    Clouds substantially affect Earth’s energy budget by reflecting solar radiation back to space and by restricting emission of thermal radiation to space. They are perhaps the largest uncertainty in our understanding of climate change, owing to disagreement among climate models and observational datasets over what cloud changes have occurred during recent decades and will occur in response to global warming. This is because observational systems originally designed for monitoring weather have lacked sufficient stability to detect cloud changes reliably over decades unless they have been corrected to remove artefacts. Here we show that several independent, empirically corrected satellite records exhibit large-scale patterns of cloud change between the 1980s and the 2000s that are similar to those produced by model simulations of climate with recent historical external radiative forcing. Observed and simulated cloud change patterns are consistent with poleward retreat of mid-latitude storm tracks, expansion of subtropical dry zones, and increasing height of the highest cloud tops at all latitudes. The primary drivers of these cloud changes appear to be increasing greenhouse gas concentrations and a recovery from volcanic radiative cooling. These results indicate that the cloud changes most consistently predicted by global climate models are currently occurring in nature.

  4. The Contributions of Local Knowledge to Cryospheric Climate Data Records

    NASA Astrophysics Data System (ADS)

    Jurt, C.; Orlove, B. S.; Dunbar, K.; Brugger, J.

    2009-12-01

    Anthropological and geographical research in high mountain regions of the world (e.g., Cruikshank 2006) has demonstrated that residents of these regions often have detailed knowledge about the history and dynamics of glaciers. We present field data from 3 sites (South Tirol, Italian Alps; Cordillera Blanca, Peruvian Andes; North Cascades, Washington) of such vernacular cryospheric climate data records (VCDRs). We indicate the large number of sources of VCDRs in individual sites; these include oral histories or narratives of changing glacial extent; place names that describe former glacier features; ritual visits to glacier fronts or surfaces that track changes; physical structures built at former glacier fronts; paintings of mountains that depict former glacier extents; local photographic collections; written records of community meetings that discuss glaciers; local monographs. (Table I shows the distribution of these records at the sites.) We indicate that these VCDRs often have a relatively small spatial extent but a temporal depth that varies from decades (North Cascades) to centuries (Italian Alps, Peruvian Andes). We discuss the features and attributes of glaciers that are reported in the VCDRs, including spatial extent, front location, surface characteristics (e.g., extent of dust cover) and surface features (e.g., crevasses, moulins). We provide initial results of efforts to validate VCDRs with records (early scientific surveys, aerial photographs, remote sensing) ordinarily used by geoscientists, and suggest that the accuracy of VCDRs in recent periods suggests the value of drawing on them for earlier periods, when scientific data are absent. We suggest research methods for collecting VCDRs from other sites as well. Reference: Cruikshank, J. 2005. Do Glaciers Listen? Local Knowledge, Colonial Encounters, and Social Imagination. Vancouver: University of British Columbia PressData Sources Present in Vernacular Cryospheric Climate Data Records in 3 Sites

  5. Evaluation of the EUMETSAT Meteosat Surface Albedo Climate Data Record

    NASA Astrophysics Data System (ADS)

    Lattanzio, Alessio; Schulz, Joerg; Roebeling, Rob; Fell, Frank; Bennartz, Ralf; Cahill, Brownwyn; Muller, Jan-Peter; Shane, Neville; Trigo, Isabel; Watson, Gill

    2013-04-01

    Understanding the climate system, with its variability and changes, requires a joint long-term international commitment from research and governmental institutions. The Global Climate Observing System (GCOS) formulated scientific requirements for the needed global observations and products including a list of relevant parameters, the so called Essential Climate Variables (ECVs). The Sustained and Coordinated Processing of Environmental Satellite Data for Climate Monitoring (SCOPE-CM) activity, is answering to these requirements by establishing an international network of facilities to ensure a continuous and sustained generation of high-quality Climate Data Records (CDR) from satellite data in compliance with the GCOS principles and guidelines. Currently, SCOPE-CM represents a partnership between operational space agencies to coordinate the generation of CDRs. Within the SCOPE-CM framework the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) has generated the Meteosat Surface Albedo (MSA) Climate Data Record that comprises up to 25 years (1982-2010) of continuous surface albedo coverage for large areas of the Earth. As part of the SCOPE-CM activity on land surface albedo, involving the operational meteorological satellite agencies in Europe (EUMETSAT), in Japan (JMA: Japanese Meteorological Agency) and in the USA (NOAA: National Oceanic and Atmospheric Administration), the MSA CDR contributes to the creation of a global harmonised surface albedo record derived from all satellites in geostationary orbit. This presentation discusses the results of an evaluation study for the MSA CDR that has been performed by independent researchers in Europe and the US. The MSA CDR has been evaluated in terms of its internal consistency, its compatibility to other satellite-derived surface albedo products, its validity against in-situ observations of superior quality, and its temporal homogeneity. The evaluation of the MSA data record has revealed a

  6. Mesozoic climates: General circulation models and the rock record

    NASA Astrophysics Data System (ADS)

    Sellwood, Bruce W.; Valdes, Paul J.

    2006-08-01

    General circulation models (GCMs) use the laws of physics and an understanding of past geography to simulate climatic responses. They are objective in character. However, they tend to require powerful computers to handle vast numbers of calculations. Nevertheless, it is now possible to compare results from different GCMs for a range of times and over a wide range of parameterisations for the past, present and future (e.g. in terms of predictions of surface air temperature, surface moisture, precipitation, etc.). GCMs are currently producing simulated climate predictions for the Mesozoic, which compare favourably with the distributions of climatically sensitive facies (e.g. coals, evaporites and palaeosols). They can be used effectively in the prediction of oceanic upwelling sites and the distribution of petroleum source rocks and phosphorites. Models also produce evaluations of other parameters that do not leave a geological record (e.g. cloud cover, snow cover) and equivocal phenomena such as storminess. Parameterisation of sub-grid scale processes is the main weakness in GCMs (e.g. land surfaces, convection, cloud behaviour) and model output for continental interiors is still too cold in winter by comparison with palaeontological data. The sedimentary and palaeontological record provides an important way that GCMs may themselves be evaluated and this is important because the same GCMs are being used currently to predict possible changes in future climate. The Mesozoic Earth was, by comparison with the present, an alien world, as we illustrate here by reference to late Triassic, late Jurassic and late Cretaceous simulations. Dense forests grew close to both poles but experienced months-long daylight in warm summers and months-long darkness in cold snowy winters. Ocean depths were warm (8 °C or more to the ocean floor) and reefs, with corals, grew 10° of latitude further north and south than at the present time. The whole Earth was warmer than now by 6 °C or

  7. Past freeze and thaw cycling in the margin of the El'gygytgyn Crater deduced from a 141 m long permafrost record

    NASA Astrophysics Data System (ADS)

    Schwamborn, G.; Meyer, H.; Schirrmeister, L.; Fedorov, G.

    2013-07-01

    Past permafrost thaw and freeze has destabilised the basin slopes of Lake El'gygytgyn in the northeastern Eurasian Arctic. This has probably promoted the release of mass movements from the lake edge to the deeper basin as known from frequently occurring turbidite layers in the lake sediment column. The continuous sediment record from the Arctic spans the last 3.6 Ma and for much of this time permafrost dynamics and lake level changes likely have played a crucial role for sediment delivery to the lake. Changes in the ground ice hydrochemical composition (pH, δ18O, δD, electrical conductivity, Na+, Mg2+, Ca2+, K+, HCO3-, Cl-, SO4-) of a 141 m long permafrost record from the western crater plain are examined to reconstruct repeated freeze and thaw cycles at the lake edge. Stable water isotope and major ion records of ground ice in the permafrost reflect both a synsedimentary palaeo-precipitation signal preserved in the near-surface permafrost (0.0 m to 9.1 m core depth) and a postdepositional record of talik thawing and refreezing in deeper layers of the core (9.1 to 141.0 m core depth). The lake marginal permafrost dynamics were controlled by lake level changes that episodically flooded the surfaces and induced thaw in the underlying frozen ground. At least three cycles of freeze and thaw during marine isotope stage (MIS) 7, possibly MIS 5, and the Allerød (AD) are identified and the hydrochemical data point to a vertical and horizontal talik refreezing through time.

  8. Past freeze and thaw cycling in the margin of the El'gygytgyn crater deduced from a 141 m long permafrost record

    NASA Astrophysics Data System (ADS)

    Schwamborn, G.; Meyer, H.; Schirrmeister, L.; Fedorov, G.

    2014-06-01

    The continuous sediment record from Lake El'gygytgyn in the northeastern Eurasian Arctic spans the last 3.6 Ma and for much of this time permafrost dynamics and lake level changes have likely played a crucial role for sediment delivery to the lake. Changes in the ground-ice hydrochemical composition (δ18O, δD, pH, electrical conductivity, Na+, Mg2+, Ca2+, K+, HCO3-, Cl-, SO4-) of a 141 m long permafrost record from the western crater plain are examined to reconstruct repeated periods of freeze and thaw at the lake edge. Stable water isotope and major ion records of ground ice in the permafrost reflect both a synsedimentary palaeo-precipitation signal preserved in the near-surface permafrost (0.0-9.1 m core depth) and a post-depositional record of thawing and refreezing in deeper layers of the core (9.1-141.0 m core depth). These lake marginal permafrost dynamics were controlled by lake level changes that episodically flooded the surfaces and induced thaw in the underlying frozen ground. During times of lake level fall these layers froze over again. At least three cycles of freeze and thaw are identified and the hydrochemical data point to a vertical and horizontal talik refreezing through time. Past permafrost thaw and freeze may have destabilised the basin slopes of Lake El'gygytgyn and this has probably promoted the release of mass movements from the lake edge to the deeper basin as known from frequently occurring turbidite layers in the lake sediment column.

  9. Herbivory, plant resistance, and climate in the tree ring record: interactions distort climatic reconstructions.

    PubMed

    Trotter, R Talbot; Cobb, Neil S; Whitham, Thomas G

    2002-07-23

    To understand climate change, dendrochronologists have used tree ring analyses to reconstruct past climates, as well as ecological processes such as herbivore population dynamics. Such reconstructions, however, have been hindered by a lack of experiments that separate the influences of confounding impacts on tree rings, such as herbivores and the interactions of multiple factors. Our long-term experiments with scale insects on resistant and susceptible pines demonstrate three major points that are important to the application of this commonly used tool. (i) Herbivory reduced tree ring growth by 25-35%. (ii) The impact on ring growth distorted climate reconstruction, resulting in the overestimation of past moisture levels by more than 2-fold. Our data suggest that, if distortion because of herbivory has been a problem in previous reconstructions, estimates of the magnitude of recent climate changes are likely to be conservative. (iii) Our studies support a detectible plant resistance x herbivore x climate interaction in the tree ring record. Because resistance and susceptibility to herbivory are known to be genetically based in many systems, the potential exists to incorporate plant genetics into the field of dendrochronology, where it may be used to screen distortions from the tree ring record. PMID:12110729

  10. Climatic record of the Iberian peninsula from lake Moncortes' sediments

    NASA Astrophysics Data System (ADS)

    Cao, Min; Huguet, Carme; Rull, Valenti; Valero, Blas; Rosell-Mele, Antoni

    2014-05-01

    Climatic record of the Iberian peninsula from lake Moncortes' sediments Min Cao1, Carme Huguet1, Valenti Rull2, Blas L. Valero-Garces3, Antoni Rosell-Melé1,4 1Institut de Ciència i Tecnologia Ambientals (ICTA), Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Catalonia, Spain; 2Institut de Botanic de Barcelona (CSIC), Passeig del Migdia s/n, 08038, Barcelona, Spain, 3 Instituto Pirenaico de Ecologıa (CSIC), Avda. Montañana 1005, 50059 Zaragoza, Spain, 4Institució Catalana de Recerca i Estudis Avançats (ICREA), 08010 Barcelona, Catalonia, Spain. The continuing buildup of industrial greenhouse gases in the atmosphere and concomitant increase in global temperatures has made much of the world's society aware that decades to centuries of environmental change lie ahead, and that these will have profound economic, political and societal impacts. The Iberian Peninsula lies in the boundary between tropical and subtropical climates and seems to amplify the climatic signals form the northern hemisphere through both atmospheric and water circulation feedbacks, making it an ideal site to monitor Northern hemisphere climate changes. This extreme sensitivity to climatic changes also makes the Iberian Peninsula extremely vulnerable to future climate changes. This is why understanding sensitivity to climate change and the consequences it will have on both climate and the hydrological cycle is key to implement preventive measures. The aim of our study is to come up with a high resolution quantitative reconstruction of climate variability (temperature, production and precipitation) in the Iberian Peninsula from lake sediments. We also want to establish the relation between those changes and the ones observed in both ice cores from Greenland and paleotemperature records from marine sediments of the continental Iberian margin. For these reasons we sampled a core in Moncortes (42.3N, 0.99E), a lake of karstic origin with an average depth of 25m and an area of 0

  11. Geodetic mass balance record with rigorous uncertainty estimates deduced from aerial photographs and lidar data - Case study from Drangajökull ice cap, NW Iceland

    NASA Astrophysics Data System (ADS)

    Magnússon, E.; Muñoz-Cobo Belart, J.; Pálsson, F.; Ágústsson, H.; Crochet, P.

    2016-01-01

    In this paper we describe how recent high-resolution digital elevation models (DEMs) can be used to extract glacier surface DEMs from old aerial photographs and to evaluate the uncertainty of the mass balance record derived from the DEMs. We present a case study for Drangajökull ice cap, NW Iceland. This ice cap covered an area of 144 km2 when it was surveyed with airborne lidar in 2011. Aerial photographs spanning all or most of the ice cap are available from survey flights in 1946, 1960, 1975, 1985, 1994 and 2005. All ground control points used to constrain the orientation of the aerial photographs were obtained from the high-resolution lidar DEM. The lidar DEM was also used to estimate errors of the extracted photogrammetric DEMs in ice- and snow-free areas, at nunataks and outside the glacier margin. The derived errors of each DEM were used to constrain a spherical semivariogram model, which along with the derived errors in ice- and snow-free areas were used as inputs into 1000 sequential Gaussian simulations (SGSims). The simulations were used to estimate the possible bias in the entire glaciated part of the DEM and the 95 % confidence level of this bias. This results in bias correction varying in magnitude between 0.03 m (in 1975) and 1.66 m (in 1946) and uncertainty values between ±0.21 m (in 2005) and ±1.58 m (in 1946). Error estimation methods based on more simple proxies would typically yield 2-4 times larger error estimates. The aerial photographs used were acquired between late June and early October. An additional seasonal bias correction was therefore estimated using a degree-day model to obtain the volume change between the start of 2 glaciological years (1 October). This correction was largest for the 1960 DEM, corresponding to an average elevation change of -3.5 m or approx. three-quarters of the volume change between the 1960 and the 1975 DEMs. The total uncertainty of the derived mass balance record is dominated by uncertainty in the volume

  12. Evidence of climate change in the 1949-2010 historical climate record of the Fort Cobb experimental watershed, Oklahoma

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Seasonal and annual precipitation and air temperature records of the Fort Cobb watershed and the Fort Cobb climate division were analyzed to identify climatic trends over the last 30 to 40 years and infer if these trends could potentially be a sign of climate change due to global warming. Findings s...

  13. Thorium-230 Dating: Technical Capabilities and Cave Climate Records (Invited)

    NASA Astrophysics Data System (ADS)

    Edwards, R.; Cheng, H.

    2013-12-01

    Because of low natural abundances of Th-230 and U-234, Th-230 dating has been limited by counting statistics ever since the first Th-230 dating studies (Barnes et al., 1956; Broecker, 1963). In this regard, we have made tremendous strides over the past quarter century, increasing the fraction of atoms of U and Th atoms that we can detect by 5 orders of magnitude (from 10-7 to 3x10-2). We have also improved the accuracy and precision of half-life values so that their contribution to uncertainty in Th-230 age is comparable to or smaller than that resulting from analysis uncertainty (Cheng et al., 2013). With ideal samples, we can date materials as old as 800,000 years and the uncertainty in age for a 100,000 year old sample, for example, may be as low as ×100 years (2σ). Given these technical capabilities, the most daunting hurdle is often the ability to find and identify materials amenable to Th-230 dating. Coarsely-crystalline, low-porosity speleothem calcite, containing negligible detrital clay has, in many cases, proven to be ideal in this respect. Over the past 15 years, Th-230 dating of cave calcite has been used to obtain precise chronologies for many cave climate records. Prominent among these are records of the oxygen isotopic composition of cave calcite, which reflect the oxygen isotopic composition of rainfall at the cave site. The most extensive records of this sort are those of the Asian Monsoon based on Chinese cave deposits. Such records now cover over 400,000 years with oxygen isotope resolution averaging several decades. In addition to the fundamental characterization of monsoon history, the records help us to understand the causes in changes in monsoon rainfall. Furthermore, we can correlate cave records to some marine and ice core records, thereby transferring precise cave chronologies to other types of records. Of note is the use of this approach to understand the timing and causes of events during glacial terminations (Cheng et al., 2009). In

  14. North Atlantic Holocene climate evolution recorded by high-resolution terrestrial and marine biomarker records

    NASA Astrophysics Data System (ADS)

    Moossen, Heiko; Bendle, James; Seki, Osamu; Quillmann, Ursula; Kawamura, Kimitaka

    2015-12-01

    Holocene climatic change is driven by a plethora of forcing mechanisms acting on different time scales, including: insolation, internal ocean (e.g. Atlantic Meridional Overturning Circulation; AMOC) and atmospheric (e.g. North Atlantic Oscillation; NAO) variability. However, it is unclear how these driving mechanisms interact with each other. Here we present five, biomarker based, paleoclimate records (air-, sea surface temperature and precipitation), from a fjordic sediment core, revealing North Atlantic terrestrial and marine climate in unprecedented detail. The Early Holocene (10.7-7.8 kyrs BP) is characterised by relatively high air temperatures while SSTs are dampened by melt water events, and relatively low precipitation. The Middle Holocene (7.8-3.2 kyrs BP) is characterised by peak SSTs, declining air temperatures and high precipitation. A pronounced marine thermal maximum occurs between ∼7-5.5 kyrs BP, 3000 years after the terrestrial thermal maximum, driven by melt water cessation and an accelerating AMOC. The neoglacial cooling, between 5.8 and 3.2 kyrs BP leads into the late Holocene. We demonstrate that an observed modern link between Icelandic precipitation variability during different NAO phases, may have existed from ∼7.5 kyrs BP. A simultaneous decoupling of both air, and sea surface temperature records from declining insolation at ∼3.2 kyrs BP may indicate a threshold, after which internal feedback mechanisms, namely the NAO evolved to be the primary drivers of Icelandic climate on centennial time-scales.

  15. Magnetic record associated with tree ring density: Possible climate proxy

    PubMed Central

    Kletetschka, Gunther; Pruner, Petr; Venhodova, Daniela; Kadlec, Jaroslav

    2007-01-01

    A magnetic signature of tree rings was tested as a potential paleo-climatic indicator. We examined wood from sequoia tree, located in Mountain Home State Forest, California, whose tree ring record spans over the period 600 – 1700 A.D. We measured low and high-field magnetic susceptibility, the natural remanent magnetization (NRM), saturation isothermal remanent magnetization (SIRM), and stability against thermal and alternating field (AF) demagnetization. Magnetic investigation of the 200 mm long sequoia material suggests that magnetic efficiency of natural remanence may be a sensitive paleoclimate indicator because it is substantially higher (in average >1%) during the Medieval Warm Epoch (700–1300 A.D.) than during the Little Ice Age (1300–1850 A.D.) where it is <1%. Diamagnetic behavior has been noted to be prevalent in regions with higher tree ring density. The mineralogical nature of the remanence carrier was not directly detected but maghemite is suggested due to low coercivity and absence of Verwey transition. Tree ring density, along with the wood's magnetic remanence efficiency, records the Little Ice Age (LIA) well documented in Europe. Such a record suggests that the European LIA was a global phenomenon. Magnetic analysis of the thermal stability reveals the blocking temperatures near 200 degree C. This phenomenon suggests that the remanent component in this tree may be thermal in origin and was controlled by local thermal condition. PMID:17381844

  16. The Seasonal Climate Record from Soreq Cave (Israel) Speleothems

    NASA Astrophysics Data System (ADS)

    Orland, I. J.; Bar-Matthews, M.; Ayalon, A.; Burstyn, Y.; Kozdon, R.; Ushikubo, T.; Matthews, A.; Meyers, S. R.; Valley, J. W.

    2011-12-01

    The slow growth rate of most speleothems prevents conventional (drill-sampling) methods from acquiring precise, seasonal-scale sampling. Micro-scale (e.g. ion microprobe and LA-ICP-MS) analysis in speleothems adds important detail to the climate record if seasonal climate variability is geochemically evident within the cave. Micro-analytical results may reveal seasonal climate history, climate dynamics over both short and long timescales, bias in conventional analyses, and local hydrological processes. High-resolution in situ analysis of Soreq speleothems provides new information about regional climate, seasonality, and abrupt climate events since 34 ka. We combine and compare conventionally measured records of δ18O from Soreq speleothems with micro-scale analysis and imaging. We use the WiscSIMS CAMECA 1280 ion microprobe to measure δ18O at sub-annual resolution (10 μm spots, 2 SD precision ~0.3%) and confocal laser fluorescence microscopy (CLFM) to image growth bands. Combined analyses of δ18O and CLFM show that couplets of bright and dark fluorescent calcite in Soreq speleothems represent annual growth bands. Organic molecules (e.g. humic acids) that are flushed into the cave from the overlying soil column cause the bright fluorescence. A quantitative measure of seasonality (Δ18O = |δ18O[dark calcite] - δ18O[bright calcite]| in a single band) in annual bands reveals both long-term trends and abrupt changes that are not quantified by conventional methods. The mean value of Δ18O decreases from 1.0% prior to the Younger Dryas (YD) to 0.7% for the Holocene (>99% confidence that mean values are not equal). The change in Δ18O correlates with a shift in the fluorescent patterns of annual bands; the fluorescence of calcite formed prior to the YD is consistently reversed within an annual band (dark precedes bright) relative to Holocene bands (bright precedes dark). Coupled differences in Δ18O and fluorescence are likely caused by changes in seasonal rainfall

  17. Daily OLR Climate Data Record - A Challenge to Homogenize Operational Satellite Observations for Climate Applications

    NASA Astrophysics Data System (ADS)

    Lee, Hai-Tien

    2014-05-01

    A data set of daily mean outgoing longwave radiation (OLR) at 1°x1° grid spanning from 1979 to 2012 was generated using infrared radiance observations from the High resolution Infrared Radiation Sounder (HIRS) and Imaging instruments onboard the international operational polar-orbiting and geostationary satellites. The instantaneous OLR can be accurately estimated by the multi-spectral regression model using narrow band radiance observations (Ellingson et al., 1989), however, there are challenges for constructing a climate data record that is homogeneous in both space and time, while maintaining radiometric accuracy. The synergy of polar-orbiting and geostationary observation systems provides advantages that much improve the homogeneity of the temporal and spatial sampling. Bias correction methodologies have been devised to maintain the radiometric accuracy. The HIRS OLR algorithm is revised to handle the problems caused by the configuration variations in the HIRS instruments over time. This removes scene-dependent inter-satellite biases. Incorporating OLR estimated from Imager instruments onboard geostationary satellites not only sufficiently resolves the diurnal variation that is critical for daily integral purpose, but it also helps to remove the artificial trends resulted from the polar-orbiter's orbital drift effects. This work produced a continuous daily OLR climate data record of more than three decades that can be very useful for climate variation and numerical model simulation assessment purposes.

  18. Snow and the ground temperature record of climate change

    NASA Astrophysics Data System (ADS)

    Bartlett, Marshall G.; Chapman, David S.; Harris, Robert N.

    2004-12-01

    Borehole temperature-depth profiles contain a record of surface ground temperature (SGT) changes with time and complement surface air temperature (SAT) analysis to infer climate change over multiple centuries. Ground temperatures are generally warmer than air temperatures due to solar radiation effects in the summer and the insulating effect of snow cover during the winter. The low thermal diffusivity of snow damps surface temperature variations; snow effectively acts as an insulator of the ground during the coldest part of the year. A numerical model of snow-ground thermal interactions is developed to investigate the effect of seasonal snow cover on annual ground temperatures. The model is parameterized in terms of three snow event parameters: onset time of the annual snow event, duration of the event, and depth of snow during the event. These parameters are commonly available from meteorological and remotely sensed data making the model broadly applicable. The model is validated using SAT, subsurface temperature from a depth of 10 cm, and snow depth data from the 6 years of observations at Emigrant Pass climate observatory in northwestern Utah and 217 station years of National Weather Service data from sites across North America. Measured subsurface temperature-time series are compared to changes predicted by the model. The model consistently predicts ground temperature changes that compare well with those observed. Sensitivity analysis of the model leads to a nonlinear relationship between the three snow event parameters (onset, duration, and depth of the annual snow event) and the influence snow has on mean annual SGT.

  19. Growing up MODIS: Towards a mature aerosol climate data record

    NASA Astrophysics Data System (ADS)

    Levy, Robert C.

    2013-05-01

    Aerosols are major players within the Earth's climate system, affecting the radiation budget, clouds and the hydrological cycle. In high concentrations near the surface, aerosols (or particulate matter, PM) affect visibility, impact air quality, and can contribute to poor health. Among others, Yoram Kaufman recognized the importance of aerosols to climate, and helped to design new instrumentation and algorithms to retrieve and quantify global aerosol properties. One instrument, known as the Moderate Imaging Resolution Spectro-radiometer (MODIS), was deployed on the AM-1 satellite (later known as Terra), part of NASA's Earth Observing System (EOS). In 1998, armed with an M.S. and job experience in neither aerosols nor satellites, I was looking for a new job. I somehow found my way to the MODIS Aerosol team. It was only a year before Terra launch, and most major decisions about the MODIS aerosol retrieval algorithms had been finalized. Since then, we worked through launch, initial evaluation of the product with AERONET and field deployments, and continued efforts to understand the product and refine retrieval algorithms. I have had opportunities to participate in field experiments, write papers, and earn my PhD. The "second generation" algorithm for aerosol retrieval over land has been hugely successful. We have collected nearly a half-million collocations with AERONET and other dataseis, made new discoveries, and have contributed to research and operational projects globally. Due to the dedication of the entire team, the MODIS aerosol product now is one of the highlights of NASA's EOS program. It is used for climate research and air quality forecasting, as well for applications not even considered before the MODIS era. More recently, a focus is on stitching the MODIS aerosol product into the "climate data record" (CDR) for global aerosol, determining whether the product has sufficient length, consistency and continuity to determine climate variability and change

  20. A satellite-derived climate data record of global radiation

    NASA Astrophysics Data System (ADS)

    Posselt, R.; Müller, R.; Stöckli, R.; Trentmann, J.

    2010-09-01

    A 25 year long continuous and consistently validated surface incoming shortwave (SIS) radiation climate data record (CDR) from METEOSAT satellites is MeteoSwiss' contribution to CM SAF (Satellite Application Facility for Climate Monitoring). CM SAF is a joint activity of several national Meteorological Services within EUMETSAT's satellite data processing (SAF - Satellite Application Facilities). CM SAF generates archives and distributes widely recognized high-quality satellite-derived products and services relevant for climate monitoring in operational mode with a special emphasis on the retrieval of climate variables such as cloud parameters, radiation budget and water vapor. The SIS CDR by MeteoSwiss and DWD is generated using an extended Heliosat algorithm which exploits the attenuation of radiation by clouds from the METEOSAT visible channel, and using the MAGIC (Mesoscale Atmospheric Global Irradiance Code) radiative transfer model that accounts for water vapor, ozone and aerosol absorption on clear sky radiation fluxes. Besides the dataset itself, a statistical analysis of the surface radiation climatology will be presented. Monthly means of surface radiation but also TOA cloud albedo are analyzed for trends, changes in patterns and also for homogeneity between the different satellites. Furthermore, the dataset is compared to reference surface radiation products from ISCCP, GEWEX and ERA interim. Ground based measurements of the BSRN (Baseline surface radiation network) and ASRB (Alpine surface radiation budget) network are used to estimate the uncertainty of the satellite surface radiation climatology. In order to satisfy the dataset accuracy required for climate variability and change studies, discontinuities due to changes in satellite instrumentation must be avoided. Therefore, a selfcalibration technique within the Heliosat algorithm is applied. It uses the 95% percentile of the measured radiance distribution obtained in a selected (nearly) always cloudy

  1. What the Sunspot Record Tells Us About Space Climate

    NASA Technical Reports Server (NTRS)

    Hathaway, David H.; Wilson, Robert M.

    2004-01-01

    The records concerning the number, sizes, and positions of sunspots provide a direct means of characterizing solar activity over nearly 400 years. Sunspot numbers are strongly correlated with modem measures of solar activity including: 10.7-cm radio flux, total irradiance, x-ray flares, sunspot area, the baseline level of geomagnetic activity, and the flux of galactic cosmic rays. The Group Sunspot Number provides information on 27 sunspot cycles, far more than any of the modem measures of solar activity, and enough to provide important details about long-term variations in solar activity or Space Climate. The sunspot record shows: 1) sunspot cycles have periods of 131 plus or minus 14 months with a normal distribution; 2) sunspot cycles are asymmetric with a fast rise and slow decline; 3) the rise time from minimum to maximum decreases with cycle amplitude; 4) large amplitude cycles are preceded by short period cycles; 5 ) large amplitude cycles are preceded by high minima; 6) although the two hemispheres remain linked in phase, there are significant asymmetries in the activity in each hemisphere; 7) the rate at which the active latitudes drift toward the equator is anti-correlated with the cycle period, 8) the rate at which the active latitudes drift toward the equator is positively correlated with the amplitude of the cycle after the next; 9) there has been a significant secular increase in the amplitudes of the sunspot cycles since the end of the Maunder Minimum (1715); and 10) there is weak evidence for a quasi-periodic variation in the sunspot cycle amplitudes with a period of about 90 years. These characteristics indicate that the next solar cycle should have a maximum smoothed sunspot number of about 1.45 plus or minus 30 in 2010 while the following cycle should have a maximum of about 70 plus or minus 30 in 2023.

  2. Climatic influences on species: Evidence from the fossil record

    USGS Publications Warehouse

    Cronin, T. M.; Schneider, C.E.

    1990-01-01

    The detailed Neogene and Quaternary paleoclimatic reconstructions now available provide a means to test how species respond to environmental change. Paleontologic studies of marine organisms show that climatic change causes evolution (via cladogenesis and anagenesis), ecophenotypic variation, migration, morphologic stasis and extinction. Evolution during climatic change is a rare event relative to the number of climatic cycles that have occurred, but climate-related environmental barriers, usually temperature, may play an important role in the isolation of populations during allopatric speciation.

  3. Evaluation of Little Ice Age cooling in Western Central Andes, suggested by paleoELAs, in contrast with global warming since late 19th century deduced from instrumental records

    NASA Astrophysics Data System (ADS)

    Ubeda, Jose; Palacios, David; Campos, Néstor; Giraldez, Claudia; García, Eduardo; Quiros, Tatiana

    2015-04-01

    This paper attempts to evaluate climate cooling (°C) during the glacial expansion phases using the product GTV•ΔELA, where GTV is the vertical air temperature gradient (°C/m) and ΔELA (m) the difference in level observed between the Equilibrium Line Altitude (ELA) reconstructions for current and past glaciers. With this aim the Area x Altitude Balance Ratio-(AABR) method was used to produce reconstructions of present ELAs (2002-2010) and paleoELAs corresponding to the last glacier advance phase. The reconstructions were produced in three study areas located along a N-S transect of the western cordillera in the Central Andes: the south-western sector of the Nevado Hualcán (9°S, 77°W; Giráldez 2011); the southern slope of the Cordillera Pariaqaqa (12°S, 76°W; Quirós, 2013) and the NW, NE, SE and SW quadrants of the Nevado Coropuna (16°S, 72°W; García 2013; Úbeda 2011; Campos, 2012). The three mountains exceed 6000 m altitude, their summit areas are covered by glaciers, and on their slopes there are existing well-conserved moraines deposited by the last advances near the present front of the ice masses. Although there are no absolute dates to confirm this hypothesis, it has been assumed that the last glacial advances occurred during the Little Ice Age (LIA), which the oxygen isotopes of the Nevado Huascarán (9°S, 77°W) date to the period 1500-1890. For the Hualcán and Pariaqaqa the mean global value of the Earth's GTV (6.5°C/km) was used, considered valid for the Tropics. On the Coropuna a GTV=8.4°C/km was used, based on high resolution sensors installed in situ since 2007 (Úbeda 2011). This gradient is approaching the upper limit of the dry adiabatic gradient (9.8°C/km), as the Coropuna region is more arid than the other case study areas. The climate cooling estimates deduced from the product GTV•ΔELA were compared with the global warming shown by the 1880-2012 series, ΔT=0.85°C, and 1850/1900-2003/2012, ΔT=0.78°C. The differences are

  4. Climate, atmosphere, and volatile inventory evolution: Polar processes, climate records, volatile inventories

    NASA Technical Reports Server (NTRS)

    Pollack, J. B.

    1988-01-01

    Climate change on Mars was driven by long term changes in the solar luminosity, variations in the partitioning of volatiles between the atmosphere and near-surface reservoirs, and astronomical variations in axial and orbital properties. There are important parallels between these drives for Mars and comparable ones for Earth. In the early history of the solar system, the Sun's luminosity was 25 to 30 percent lower than its current value. It is suggested that an early benign climate on Earth was due to the presence of much more carbon dioxide in its atmosphere at these early times than currently resides there. Such a partitioning of carbon dioxide, at the expense of the carbonate rock reservoir, may have resulted from a more vigorous tectonic and volcanic style at early times. Such a line of reasoning may imply that much more carbon dioxide was present in the Martian atmosphere during the planet's early history than resides there today. It is now widely recognized that astronomical variations of the Earth's axial and orbital characteristics have played a dominant role in causing the succession of glacial and interglacial periods characterizing the last several million years. The magnitude of the axial and eccentricity variations are much larger for Mars than for Earth. Such changes on Mars could result in sizeable variations in atmospheric pressure, dust storm activity, and the stability of perennial carbon dioxide and water ice polar caps. These quasi-periodic climate changes occur on periods of 100,000 to 1,000,000 years and may be recorded in the sedimentary layers of the polar layered terrain.

  5. Climatic controls on hurricane patterns: a 1200-y near-annual record from Lighthouse Reef, Belize

    NASA Astrophysics Data System (ADS)

    Denommee, K. C.; Bentley, S. J.; Droxler, A. W.

    2014-01-01

    Tropical cyclones (TCs) are powerful agents of destruction, and understanding climatic controls on TC patterns is of great importance. Over timescales of seasons to several decades, relationships among TC track, frequency, intensity and basin-scale climate changes are well documented by instrumental records. Over centuries to millennia, climate-shift influence on TC regimes remains poorly constrained. To better understand these relationships, records from multiple locations of TC strikes spanning millennia with high temporal resolution are required, but such records are rare. Here we report on a highly detailed sedimentary proxy record of paleo-TC strikes from the Blue Hole of Lighthouse Reef, Belize. Our findings provide an important addition to other high-resolution records, which collectively demonstrate that shifts between active and inactive TC regimes have occurred contemporaneously with shifts hemispheric-scale oceanic and atmospheric circulation patterns such as MDR SSTs and NAO mode, rather than with changes in local climate phenomena as has previously been suggested.

  6. Expressions of climate perturbations in western Ugandan crater lake sediment records during the last 1000 years

    NASA Astrophysics Data System (ADS)

    Mills, K.; Ryves, D. B.; Anderson, N. J.; Bryant, C. L.; Tyler, J. J.

    2014-08-01

    Equatorial East Africa has a complex regional patchwork of climate regimes, sensitive to climate fluctuations over a variety of temporal and spatial scales during the late Holocene. Understanding how these changes are recorded in and interpreted from biological and geochemical proxies in lake sedimentary records remains a key challenge to answering fundamental questions regarding the nature, spatial extent and synchroneity of climatic changes seen in East African palaeo-records. Using a paired lake approach, where neighbouring lakes share the same geology, climate and landscape, it might be expected that the systems will respond similarly to external climate forcing. Sediment cores from two crater lakes in western Uganda spanning the last ~1000 years were examined to assess diatom community responses to late Holocene climate and environmental changes, and to test responses to multiple drivers using redundancy analysis (RDA). These archives provide annual to sub-decadal records of environmental change. Lakes Nyamogusingiri and Kyasanduka appear to operate as independent systems in their recording of a similar hydrological response signal via distinct diatom records. However, whilst their fossil diatom records demonstrate an individualistic, indirect response to external (e.g. climatic) drivers, the inferred lake levels show similar overall trends and reflect the broader patterns observed in Uganda and across East Africa. The lakes appear to be sensitive to large-scale climatic perturbations, with evidence of a dry Medieval Climate Anomaly (MCA; ca. AD 1000-1200). The diatom record from Lake Nyamogusingiri suggests a drying climate during the main phase of the Little Ice Age (LIA) (ca. AD 1600-1800), whereas the diatom response from the shallower Lake Kyasanduka is more complex (with groundwater likely playing a key role), and may be driven more by changes in silica and other nutrients, rather than by lake level. The sensitivity of these two Ugandan lakes to regional

  7. Challenges in assessing the contribution of climate change to observed record-breaking heat waves

    NASA Astrophysics Data System (ADS)

    Perlwitz, J.; Xu, T.; Quan, X.; Hoerling, M. P.; Dole, R. M.

    2013-12-01

    Record-setting heat waves have large impacts on public health and society due to increased mortality rate, wild fires, property damages and agricultural loss. There is increasing interest in understanding the causes of such extreme events including the role of climate change. We use the example of the link between atmospheric blocking frequency and summertime seasonal temperature extreme to address some challenges in determining the relative contributions of natural variability and climate change on the occurrence and magnitude of extreme climate-related events. We utilize the 62-year record of observational data from 1960 to 2011 and long integrations with the NCARs Community Climate System Model Version 4 (CCSM4). This climate model represents well atmospheric blocking frequency and related weather features over the European/Ural region. Both observations and long climate integrations suggest that seasonal temperature extremes over the Northern European/Ural region are strongly conditioned by blocking. We illustrate that one challenge in climate event attribution is related to the fact that very long records are necessary to sufficiently sample the frequency of occurrence of the principal driver of a record-setting climate event. We further illustrate that there is a strong regional dependence on how the link between blocking frequency and extreme temperature anomalies is modified due to climate change suggesting that event attribution results are often not transferable from one region to another.

  8. Ice Core Records of Past Climate and Evidence for Present and Future Glacier Loss across the Third Pole

    NASA Astrophysics Data System (ADS)

    Thompson, L. G.; Yao, T.; Davis, M. E.; Mosley-Thompson, E. S.

    2010-12-01

    High altitude temperatures in the tropics are predicted by IPCC models (2007) to warm twice as much as the 3oC rise projected for global sea surface temperature by 2100 AD. Data collected over the last thirty years from ice cores drilled in five glaciers across the Tibetan Plateau and the Himalaya document this amplification. These ice cores, drilled at elevations ranging from 5325 to 7200 masl, have provided high-resolution climate records that show greater average stable isotopic depletion with increasing altitude for the last 1000 years. Four of these core records extend back over one thousand years. Comparison of the average δ18O from 1939 to 1987 to that from 1938 to 1000 AD illustrates a recent isotopic enrichment that is also enhanced with altitude. The greatest enrichment from AD 1938 to 1987 relative to the previous 938 years occurred at the highest elevation site (Dasuopu), presumably where the greatest warming is occurring. These trends are consistent with instrumental temperature records collected since the 1950s across the Plateau as well as with model predictions of vertical amplification of temperatures in the tropics. The isotopic profile from a fifth core drilled on Naimona’nyi (6100 masl) is not included as recent melting from the top of the glacier has obliterated the upper 40 to 50 years of the record. Naimona’nyi (also known as Gurla Mandata) is located near the headwaters of the Ganges and Brahmaputra Rivers, and is experiencing loss of ice from the surface, as deduced by the absence of both the 1962-63 beta radioactive signal that is seen in other Asian cores and the 1951-52 36Cl signal from the Ivy thermonuclear test that appears in other tropical glaciers. Recent mass balance measurements indicate that no net accumulation is occurring on this glacier in today’s climate. These ice core records also provide evidence that these ice fields are sensitive to fluctuations in the intensity of the South Asian Monsoon. Thus, a growing body of

  9. Climate Data Records (CDRs) for Ice Motion and Ice Age

    NASA Astrophysics Data System (ADS)

    Tschudi, M. A.; Fowler, C.; Maslanik, J. A.; Stroeve, J. C.

    2011-12-01

    Climate Data Records (CDRs) for remotely-sensed Arctic sea ice motion and sea ice age are under development by our group at the University of Colorado, Boulder. The ice motion product, archived at NSIDC, has a considerable history of use, while sea ice age is a relatively new product. Our technique to estimate sea ice motion utilizes images from SSM/I, as well as SMMR and the series of AVHRR sensors to estimate the daily motion of ice parcels. This method is augmented by incorporating ice motion observations from the network of drifting buoys deployed as part of the International Arctic Buoy Program. Our technique to calculate ice age relies on following the actual age of the ice for each ice parcel, categorizing the parcel as first-year ice, second-year, ice, etc. based on how many summer melt seasons the ice parcel survives. Both of these research-grade products have been interpolated onto 25x25 km grid points spanning the entire Arctic Ocean using the Equal-Area Scalable Earth (EASE) grid. Datasets generated from this program have shown that the Arctic ice cover has experienced a significant (> 70%) decline in multiyear ice over the last 20 years, leaving a younger ice cover in 2011. By comparing ice age derived by the Lagrangian tracking method to ice thickness estimated by Ice, Cloud and land Elevation Satellite (ICESat) Geoscience Laser Altimeter System (GLAS) data, it is observed that ice age is linearly related to ice thickness, up to an age of 10 years. Therefore, the shift in dominance of multiyear ice to first-year ice relates to a significant thinning of the ice. This thinning is estimated to correspond to a 40% reduction in ice volume in the last 20 years. An ancillary dataset (APP-X) produced by the University of Wisconsin, Madison has been combined with the ice motion product to monitor the properties of the sea ice parcels tracked by the ice motion product. This dataset includes ice surface and 2-meter air temperature, albedo, downwelling shortwave

  10. Abundant climatic information in water stable isotope record from a maritime glacier on southeastern Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Zhao, Huabiao; Xu, Baiqing; Li, Zhen; Wang, Mo; Li, Jiule; Zhang, Xiaolong

    2016-04-01

    Climatic significance of ice core stable isotope record in the Himalayas and southern Tibetan Plateau (TP), where the climate is alternately influenced by Indian summer monsoon and mid-latitude westerlies, is still debated. A newly drilled Zuoqiupu ice core from a temperate maritime glacier on the southeastern TP covering 1942-2011 is investigated in terms of the relationships between δ18O and climate parameters. Distinct seasonal variation of δ18O is observed due to high precipitation amount in this area. Thus the monsoon (June to September) and non-monsoon (October to May) δ18O records are reconstructed, respectively. The temperature effect is identified in the annual δ18O record, which is predominantly contributed by temperature control on the non-monsoon precipitation δ18O record. Conversely, the negative correlation between annual δ18O record and precipitation amount over part of Northeast India is mostly contributed by the monsoon precipitation δ18O record. The variation of monsoon δ18O record is greatly impacted by the Indian summer monsoon strength, while that of non-monsoon δ18O record is potentially associated with the mid-latitude westerly activity. The relationship between Zuoqiupu δ18O record and Sea Surface Temperature (SST) is found to be inconsistent before and after the climate shift of 1976/1977. In summer monsoon season, the role of SST in the monsoon δ18O record is more important in eastern equatorial Pacific Ocean and tropical Indian Ocean before and after the shift, respectively. In non-monsoon season, however, the Atlantic Multidecadal Oscillation has a negative impact before but positive impact after the climate shift on the non-monsoon δ18O record.

  11. The GOME-type Total Ozone Essential Climate Variable (GTO-ECV) data record from the ESA Climate Change Initiative

    NASA Astrophysics Data System (ADS)

    Coldewey-Egbers, M.; Loyola, D. G.; Koukouli, M.; Balis, D.; Lambert, J.-C.; Verhoelst, T.; Granville, J.; van Roozendael, M.; Lerot, C.; Spurr, R.; Frith, S. M.; Zehner, C.

    2015-09-01

    We present the new GOME-type Total Ozone Essential Climate Variable (GTO-ECV) data record which has been created within the framework of the European Space Agency's Climate Change Initiative (ESA-CCI). Total ozone column observations - based on the GOME-type Direct Fitting version 3 algorithm - from GOME (Global Ozone Monitoring Experiment), SCIAMACHY (SCanning Imaging Absorption SpectroMeter for Atmospheric CHartographY), and GOME-2 have been combined into one homogeneous time series, thereby taking advantage of the high inter-sensor consistency. The data record spans the 15-year period from March 1996 to June 2011 and it contains global monthly mean total ozone columns on a 1°× 1° grid. Geophysical ground-based validation using Brewer, Dobson, and UV-visible instruments has shown that the GTO-ECV level 3 data record is of the same high quality as the equivalent individual level 2 data products that constitute it. Both absolute agreement and long-term stability are excellent with respect to the ground-based data, for almost all latitudes apart from a few outliers which are mostly due to sampling differences between the level 2 and level 3 data. We conclude that the GTO-ECV data record is valuable for a variety of climate applications such as the long-term monitoring of the past evolution of the ozone layer, trend analysis and the evaluation of chemistry-climate model simulations.

  12. The GOME-type Total Ozone Essential Climate Variable (GTO-ECV) data record from the ESA Climate Change Initiative

    NASA Astrophysics Data System (ADS)

    Coldewey-Egbers, M.; Loyola, D. G.; Koukouli, M.; Balis, D.; Lambert, J.-C.; Verhoelst, T.; Granville, J.; van Roozendael, M.; Lerot, C.; Spurr, R.; Frith, S. M.; Zehner, C.

    2015-05-01

    We present the new GOME-type Total Ozone Essential Climate Variable (GTO-ECV) data record which has been created within the framework of the European Space Agency's Climate Change Initiative (ESA-CCI). Total ozone column observations - based on the GOME-type Direct Fitting version 3 algorithm - from GOME (Global Ozone Monitoring Experiment), SCIAMACHY (SCanning Imaging Absorption SpectroMeter for Atmospheric CHartographY), and GOME-2 have been combined into one homogeneous time series, thereby taking advantage of the high inter-sensor consistency. The data record spans the 15-year period from March 1996 to June 2011 and it contains global monthly mean total ozone columns on a 1° × 1° grid. Geophysical ground-based validation using Brewer, Dobson, and UV-visible instruments has shown that the GTO-ECV level 3 data record is of the same high quality as the equivalent individual level 2 data products that constitute it. Both absolute agreement and long-term stability are excellent with respect to the ground-based data, for almost all latitudes apart from a few outliers which are mostly due to sampling differences between the level 2 and level 3 data. We conclude that the GTO-ECV data record is valuable for a variety of climate applications such as the long-term monitoring of the past evolution of the ozone layer, trend analysis and the evaluation of Chemistry-Climate Model simulations.

  13. A composite annual-resolution stalagmite record of North Atlantic climate over the last three millennia

    NASA Astrophysics Data System (ADS)

    Baker, Andy; C. Hellstrom, John; Kelly, Bryce F. J.; Mariethoz, Gregoire; Trouet, Valerie

    2015-06-01

    Annually laminated stalagmites can be used to construct a precise chronology, and variations in laminae thickness provide an annual growth-rate record that can be used as a proxy for past climate and environmental change. Here, we present and analyse the first composite speleothem annual growth-rate record based on five stalagmites from the same cave system in northwest Scotland, where precipitation is sensitive to North Atlantic climate variability and the winter North Atlantic Oscillation (NAO). Our 3000-year record confirms persistently low growth-rates, reflective of positive NAO states, during the Medieval Climate Anomaly (MCA). Another persistently low growth period occurring at 290-550 CE coincides with the European Migration Period, and a subsequent period of sustained fast growth-rate (negative NAO) from 600-900 AD provides the climate context for the Viking Age in northern and western Europe.

  14. A composite annual-resolution stalagmite record of North Atlantic climate over the last three millennia.

    PubMed

    Baker, Andy; C Hellstrom, John; Kelly, Bryce F J; Mariethoz, Gregoire; Trouet, Valerie

    2015-01-01

    Annually laminated stalagmites can be used to construct a precise chronology, and variations in laminae thickness provide an annual growth-rate record that can be used as a proxy for past climate and environmental change. Here, we present and analyse the first composite speleothem annual growth-rate record based on five stalagmites from the same cave system in northwest Scotland, where precipitation is sensitive to North Atlantic climate variability and the winter North Atlantic Oscillation (NAO). Our 3000-year record confirms persistently low growth-rates, reflective of positive NAO states, during the Medieval Climate Anomaly (MCA). Another persistently low growth period occurring at 290-550 CE coincides with the European Migration Period, and a subsequent period of sustained fast growth-rate (negative NAO) from 600-900 AD provides the climate context for the Viking Age in northern and western Europe. PMID:26068805

  15. A composite annual-resolution stalagmite record of North Atlantic climate over the last three millennia

    PubMed Central

    Baker, Andy; C. Hellstrom, John; Kelly, Bryce F. J.; Mariethoz, Gregoire; Trouet, Valerie

    2015-01-01

    Annually laminated stalagmites can be used to construct a precise chronology, and variations in laminae thickness provide an annual growth-rate record that can be used as a proxy for past climate and environmental change. Here, we present and analyse the first composite speleothem annual growth-rate record based on five stalagmites from the same cave system in northwest Scotland, where precipitation is sensitive to North Atlantic climate variability and the winter North Atlantic Oscillation (NAO). Our 3000-year record confirms persistently low growth-rates, reflective of positive NAO states, during the Medieval Climate Anomaly (MCA). Another persistently low growth period occurring at 290-550 CE coincides with the European Migration Period, and a subsequent period of sustained fast growth-rate (negative NAO) from 600-900 AD provides the climate context for the Viking Age in northern and western Europe. PMID:26068805

  16. Holocene Climate and Catchment-Specific Responses to Climate Change, Recorded in a Transect of Icelandic Lakes

    NASA Astrophysics Data System (ADS)

    Geirsdottir, A.; Axford, Y.; Florian, C. R.; Miller, G. H.; Crump, S. E.; Larsen, D. J.; Olafsdóttir, S.; Thordarson, T.; Blair, C.

    2015-12-01

    Holocene paleoclimate reconstructions from the northern North Atlantic landmasses exhibit greater responses to climate forcings than other Arctic regions presumably tied to changes in North Atlantic ocean-atmosphere circulation. Here we present an overview of high-resolution, precisely dated and PSV synchronized Holocene lake sediment records on Iceland, where we employ diverse proxies at sites spanning a broad modern climate gradient, from the presently glaciated highlands to the coastal lowlands. Despite substantial differences in catchment specific processes that influence each lake record, the multi-proxy reconstructions over the last 10 ka show remarkably consistent trends, especially throughout the mid to late Holocene cooling related to the slow decrease in summer insolation. Of particular note are highly non-linear abrupt departures of centennial scale summer cold periods such as at 5.5 ka, ~4.2 ka; ~3.0 ka, ~1.5 ka, 0.7 ka, and 0.2 ka. Some of the abrupt shifts may be related to Icelandic volcanism influencing catchment stability, but the lack of a full recovery to pre-existing values after the perturbation suggests increased periglacial activity, decreased vegetation cover, and glacier growth in Iceland. That these shifts reflect regional climate changes is also supported by contemporaneous shifts documented elsewhere in the northern North Atlantic region. Although timing and abruptness of these shifts is similar between our Icelandic lake records, their magnitude can differ substantially. Regional-scale factors such as volcanism likely modulate climatic responses to radiative forcing; and at the same time, local watershed characteristics like vegetation cover and soil properties produce site-specific environmental responses to climate change. Our Icelandic lake records provide opportunities to observe the precise timing of local climate shifts and corresponding environmental responses, and thus to disentangle these effects.

  17. The insect response to climate change: Perspectives from the Quaternary record

    SciTech Connect

    Ashworth, A.C.; Schwert, D.P. . Quaternary Entomology Lab.)

    1993-03-01

    Data based on museum collections of insects are generally inadequate to answer questions related to the response of insects to recent and potential changes in climate. The most important source of information for this purpose is the late Quaternary fossil record. Abundant, well-preserved, [sup 14]C-dated assemblages of insect fossils provide information with which to answer the following questions: (1) will climate change result in speciation--all evidence suggests that species are constant through the climate changes of the late Quaternary, future climate change would not be expected to result in accelerated rates of speciation; (2) will climate change result in extinction--few species became extinct as a result of the large-scale changes in climate and physical environment during the quaternary, although large-scale extirpation might occur, future climate change would not be expected to result in widespread extinction of species; (3) will climate change result in changes in geographic distribution--species survived late Quaternary climatic change through the ability of individuals to disperse into suitable habitats. The result was large changes in geographic distribution of species, as exemplified by the succession of faunal changes that occurred in response to the climatic changes of the late Wisconsinan in the midcontinent, future climate change would be expected to result in significant range changes of species.

  18. SARAH - A new homogeneous climate data record of surface radiation

    NASA Astrophysics Data System (ADS)

    Müller, Richard; Trentmann, Jörg; Träger-Chatterjee, Christine; Pfeifroth, Uwe

    2015-04-01

    Long-term observations of the surface radiation budget and cloud radiation properties are crucial for climate monitoring. Ground-based measurements provide accurate information for specific sites, but only satellite observations and data from reanalysis can provide consistent spatial information on the surface radiation budget for climate monitoring, in particular in regions with limited coverage of well maintained ground based measurements (e.g. ocean, Africa). Here, we present the new release of solar surface irradiance and cloud albedo derived from geostationary Meteosat imagery (1983 to 2013) within the EUMETSAT Satellite Application Facility on Climate Monitoring (CM SAF). The first release of the data set is widely used, e.g. in the solar energy community (e.g. PVGIS, http://re.jrc.ec.europa.eu/pvgis) and for validation of numerical weather prediction (e.g. ECMWF, DWD). The data set has a high temporal (hourly, daily and monthly means) and spatial resolution (0.05x0.05 deg) and is available free of charge from www.cmsaf.eu. The data cover Europe, Africa and the surrounding oceans. The quality of the data have been evaluated with surface measurements and compared with other satellite-based data sets. Respective results will be briefly presented. It will be shown that the CM SAF data set is well suited for climate monitoring, e.g for monitoring and analysis of extremes and trends. Within this scope key applications of the data will be presented. These include the analysis of radiation processes, extremes (heat waves) and trends for Europe, Africa and the ocean as well as solar energy applications.

  19. Climate forcing and Neanderthal extinction in Southern Iberia: insights from a multiproxy marine record

    NASA Astrophysics Data System (ADS)

    Jiménez-Espejo, Francisco J.; Martínez-Ruiz, Francisca; Finlayson, Clive; Paytan, Adina; Sakamoto, Tatsuhiko; Ortega-Huertas, Miguel; Finlayson, Geraldine; Iijima, Koichi; Gallego-Torres, David; Fa, Darren

    2007-04-01

    Paleoclimate records from the western Mediterranean have been used to further understand the role of climatic changes in the replacement of archaic human populations inhabiting South Iberia. Marine sediments from the Balearic basin (ODP Site 975) was analysed at high resolution to obtain both geochemical and mineralogical data. These data were compared with climate records from nearby areas. Baexcces was used to characterize marine productivity and then related to climatic variability. Since variations in productivity were the consequence of climatic oscillations, climate/productivity events have been established. Sedimentary regime, primary marine productivity and oxygen conditions at the time of population replacement were reconstructed by means of a multiproxy approach. Climatic/oceanographic variations correlate well with Homo spatial and occupational patterns in Southern Iberia. It was found that low ventilation (U/Th), high river supply (Mg/Al), low aridity (Zr/Al) and low values of Baexcess coefficient of variation, may be linked with Neanderthal hospitable conditions. We attempt to support recent findings which claim that Neanderthals populations continued to inhabit southern Iberia between 30 and ˜28 ky cal BP and that this persistence was due to the specific characteristics of South Iberian climatic refugia. Comparisons of our data with other marine and continental records appear to indicate that conditions in South Iberia were highly inhospitable at ˜24 ky cal BP. Thus, it is proposed that the final disappearance of Neanderthals in this region could be linked with these extreme conditions.

  20. Climate change impacts on Swiss groundwater: insights from historical records

    NASA Astrophysics Data System (ADS)

    Figura, S.; Livingstone, D. M.; Kipfer, R.

    2012-04-01

    Knowledge of the impact of climate change on groundwater is limited mainly by a lack of relevant long-term data that would allow the effects of climatic forcing to be assessed empirically. With the aim of assessing the consequences of climate change on groundwater, we collected and statistically analysed historical groundwater data from Switzerland. While most existing studies have focused on the impact of climate change on groundwater quantity, we focus on groundwater quality. As measures of groundwater quality we chose groundwater temperature and oxygen concentration because of their importance for biogeochemical processes and for reasons of data availability. Our analyses show that in aquifers that are recharged by riverbank infiltration, groundwater temperature has increased by 1°C - 1.5°C over the last 30 years. By contrast, in aquifers that are recharged only by the percolation of precipitation, increases in groundwater temperature are slight or non-existent. A detailed analysis of groundwater temperatures measured in the pumping wells of five aquifers that are recharged by riverbank infiltration revealed that an abrupt temperature increase in the late 1980s, which was also detected in Swiss air temperature and river water temperatures and which is traceable ultimately to a change in the behaviour of the Arctic Oscillation, accounted for a large proportion of the total groundwater warming [1]. Oxygen concentrations were available for four of the five aquifers we investigated. In two of these aquifers the oxygen concentration underwent a strong decrease, in the third a slight decrease, and in the fourth a slight increase. Neither long-term trends in river water oxygen concentration nor altered hydraulic conditions seem to be responsible for the long-term trends in groundwater oxygen concentrations. However, the decreasing oxygen concentrations were accompanied by decreasing DOC concentrations in the groundwater, while DOC concentrations in the river water

  1. What can we learn from the Paleo-Records about Future Arctic Climate Change?

    NASA Astrophysics Data System (ADS)

    Tremblay, B.; Huard, D. B.; Schmidt, G. A.; de Vernal, A.

    2014-12-01

    The Coupled Model Intercomparison Project, Phase 5 (CMIP5), include historical simulations from the 20th century, future climate simulations following different Representative Concentration Pathways (RCPs) for the 21st Century and beyond, and, for the first time in CMIP, three sets of paleo-climate simulations of the recent past for which more paleo-proxi-data exist. We use simulations of the Mid-Holocene (MH) climate (6K BP) from General Circulation Models participating in CMIP5 to constrain future projections of Arctic climate change by the same models. During the Mid-Holocene, the Arctic received approximately 50 W/m2 more solar radiation at the top of the atmosphere during summer, a similar increase to what is projected from greenhouse gas forcing for the middle of the 21st century. The constraint in our analysis arise from a measure of the ability of GCMs to hindcast MH climate using a suite of both land paleo-records - which are much more abundant for high latitudes than ocean proxy - and ocean paleo-record. Results show that GCMs with skill at simulating the MH climate and today's climate give more realistic future projections of the sea ice decline in forced climate simulations of the 21st century participating in the IPCC-AR5.

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

    USGS Publications Warehouse

    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.

  3. Assessing the continuity of the blue ice climate record at Patriot Hills, Horseshoe Valley, West Antarctica

    NASA Astrophysics Data System (ADS)

    Winter, Kate; Woodward, John; Dunning, Stuart A.; Turney, Chris S. M.; Fogwill, Christopher J.; Hein, Andrew S.; Golledge, Nicholas R.; Bingham, Robert G.; Marrero, Shasta M.; Sugden, David E.; Ross, Neil

    2016-03-01

    We use high-resolution ground-penetrating radar (GPR) to assess the continuity of the Blue Ice Area (BIA) horizontal climate record at Patriot Hills, Horseshoe Valley, West Antarctica. The sequence contains three pronounced changes in deuterium isotopic values at ~18 cal ka, ~12 cal ka, and ~8 cal ka. GPR surveys along the climate sequence reveal continuous, conformable dipping isochrones, separated by two unconformities in the isochrone layers, which correlate with the two older deuterium shifts. We interpret these unconformities as discontinuities in the sequence, rather than direct measures of climate change. Ice sheet models and Internal Layer Continuity Index plots suggest that the unconformities represent periods of erosion occurring, as the former ice surface was scoured by katabatic winds in front of mountains at the head of Horseshoe Valley. This study demonstrates the importance of high-resolution GPR surveys for investigating both paleoflow dynamics and interpreting BIA climate records.

  4. Climate Interpretations from the WAIS Divide Water Isotope Record

    NASA Astrophysics Data System (ADS)

    Jones, Tyler R.; White, James W. C.; Cuffey, Kurt M.; Steig, Eric J.; Fudge, Tyler J.; Vaughn, Bruce H.; Morris, Valerie A.; Gkinis, Vasileios; Markle, Bradley R.; Schoenemann, Spruce W.

    2014-05-01

    Ultra-high resolution water isotope measurements (δD, δ18O and deuterium excess) from the WAIS Divide ice core have been analyzed using a continuous flow system (CFA). The CFA measurements (INSTAAR, University of Colorado) have been averaged to 1 cm and compared with 50 cm discrete measurements (Isolab, University of Washington). Downsampling the CFA data, we find significant (>99%) multi-taper coherence between the two measurement techniques (δD and δ18O). The deuterium excess measurements are more difficult to reproduce at high-resolution, but are significantly coherent at longer time scales (100-1000 years). Frequency analysis of the CFA water isotope signal (δD and δ18O) shows 1-year power persists throughout the Holocene and part-way into the Glacial. At 5 ka bp about 50% of the initial water isotope annual amplitude remains, whereas at 9 ka bp about 20% remains. By 15 ka bp yearly power has mostly disappeared. We use the exceptional preservation of the water isotope signal to undertake various analyses including: 1) Interpretation of abrupt climate changes (e.g. AIM events), 2) Frequency analysis of ENSO-type climate oscillations throughout the Holocene and the late-Glacial (e.g. 2-7 year periodicities), and 3) The effects of diffusion on the water isotope signal (e.g. diffusion constrains the temperature, accumulation during firn densification, and dynamic thinning history, which could be used to invert for these parameters). These analyses are ongoing as we continue to develop our methodologies and CFA system processing code.

  5. Assessing the Pleistocene hemispheric climate links through correlating loess, marine and ice-core records

    NASA Astrophysics Data System (ADS)

    Guo, Z.

    2015-12-01

    Near continuous loess-soil records in China cover the past 22 million years. Here, we compare various independent climate proxies from the terrestrial, marine and ice-core domains to re-evaluate the regional and global significance of the China loess with special emphases to the Quaternary portion. The results confirm that the intensity of loess deposition in China is closely coupled with the northern high latitude climate from the over-orbital to millennial scales, and that loess accumulation rates (LAR) and loess particle-size reflect many features of the northern high latitude ice conditions. Consequently, correlating the loess and marine records could offer the possibility for addressing the hemispheric climate links. Our loess-marine correlations show that both records are broadly coupled during the Pleistocene. However, numerous decoupled features exist between the two records. Marine oxygen isotope record shows a general trend of increased ice-volume during the Pleistocene. This trend has no clear reflection in the loess LAR and grain-size data. A prominent change at ~ 430 ka, referred to as the Mid-Brunhes Event (MBE), is clearly documented in both marine and EPICA ice records while its reflections in loess are rather ambiguous. Both marine and EPICA data show a cooler-than-average interglacial for the marine-oxygen isotope stage 13 (MIS-13) while a series of terrestrial records show a warm-extreme interglacial for the northern hemisphere. During a number of glacial intervals, such as MIS-16, MIS 14, MIS-12 and MIS-3, interglacial-level of loess grain-size are observed while they have no obvious reflections in the marine and EPICA ice records. Based on a multi-proxy approach, we argue that these decoupled features between the loess and marine records are attributable to the asymmetrical behaviors of the Pleistocene climates between the southern and northern hemispheres.

  6. Generation of Reliable Climate Data Records From Satellite Data: The Calibration and Inter-Calibration Challenge

    NASA Astrophysics Data System (ADS)

    Schulz, Joerg; Roebeling, Rob; Hewison, Tim; Wagner, Sebastien; Lattanzio, Alessio

    2013-04-01

    Earth observations constitute a critical input for monitoring and advancing understanding of the Earth climate system including its variability and change. From observations taken by satellites or ground-based systems so-called Climate Data Records (CDRs) also known as time series of Essential Climate Variables (ECV) can be created. In particular long records of satellite data have a high potential for being utilised for assimilation into Numerical Weather Prediction (NWP) models to create a physically consistent model-based reanalysis, for the assessment of climate model performance and climate studies directly targeting an improved understanding of the mechanisms of climate change and variability. However, the requirements concerning long-term stability and uncertainty for CDRs are challenging. This is because many long-term satellite observations are provided by operational satellite systems build for the purpose of weather and not climate monitoring. Thus, a high demand for satellite radiance data records with quality analysed and corrected observations as well as a homogenisation over time facilitating the use of multiple satellites carrying similar and different instruments exists. The improvement of the quality of a multi-satellite data record is clearly an international challenge. For instance the creation of a CDR from all past and current geostationary satellite instruments needs a collaboration of space agencies worldwide. The WMO Space Program has initialised two relevant activities leading to improved CDRs. The Global Space-based Inter-Calibration System (GSICS) aims at the development of techniques to ensure comparability of satellite measurements taken at different times and locations by different instruments operated by different satellite agencies, and ties all measurements to SI units. The Sustained Coordinated Processing of Environmental Satellite Data for Climate Monitoring (SCOPE-CM) initiative is a major activity to establish a sustained

  7. Solar cycles or random processes? Evaluating solar variability in Holocene climate records.

    PubMed

    Turner, T Edward; Swindles, Graeme T; Charman, Dan J; Langdon, Peter G; Morris, Paul J; Booth, Robert K; Parry, Lauren E; Nichols, Jonathan E

    2016-01-01

    Many studies have reported evidence for solar-forcing of Holocene climate change across a range of archives. These studies have compared proxy-climate data with records of solar variability (e.g. (14)C or (10)Be), or have used time series analysis to test for the presence of solar-type cycles. This has led to some climate sceptics misrepresenting this literature to argue strongly that solar variability drove the rapid global temperature increase of the twentieth century. As proxy records underpin our understanding of the long-term processes governing climate, they need to be evaluated thoroughly. The peatland archive has become a prominent line of evidence for solar forcing of climate. Here we examine high-resolution peatland proxy climate data to determine whether solar signals are present. We find a wide range of significant periodicities similar to those in records of solar variability: periods between 40-100 years, and 120-140 years are particularly common. However, periodicities similar to those in the data are commonly found in random-walk simulations. Our results demonstrate that solar-type signals can be the product of random variations alone, and that a more critical approach is required for their robust interpretation. PMID:27045989

  8. Solar cycles or random processes? Evaluating solar variability in Holocene climate records

    PubMed Central

    Turner, T. Edward; Swindles, Graeme T.; Charman, Dan J.; Langdon, Peter G.; Morris, Paul J.; Booth, Robert K.; Parry, Lauren E.; Nichols, Jonathan E.

    2016-01-01

    Many studies have reported evidence for solar-forcing of Holocene climate change across a range of archives. These studies have compared proxy-climate data with records of solar variability (e.g. 14C or 10Be), or have used time series analysis to test for the presence of solar-type cycles. This has led to some climate sceptics misrepresenting this literature to argue strongly that solar variability drove the rapid global temperature increase of the twentieth century. As proxy records underpin our understanding of the long-term processes governing climate, they need to be evaluated thoroughly. The peatland archive has become a prominent line of evidence for solar forcing of climate. Here we examine high-resolution peatland proxy climate data to determine whether solar signals are present. We find a wide range of significant periodicities similar to those in records of solar variability: periods between 40–100 years, and 120–140 years are particularly common. However, periodicities similar to those in the data are commonly found in random-walk simulations. Our results demonstrate that solar-type signals can be the product of random variations alone, and that a more critical approach is required for their robust interpretation. PMID:27045989

  9. The secret lives of corals: Climate records from coral chemistry

    SciTech Connect

    Beck, J.W.; Smoker, M.; Burr, G.

    1995-12-01

    Corals can provide archives of a diverse suite of information about the ocean surface mixed layer, including records of ocean surface temperature (via coral Sr/Ca or U/Ca measurements), salinity (via {gamma}{sup 18}O measurements), biologic activity (via {gamma}{sup 13}C measurements), and ocean/atmosphere CO{sub 2} exchange rates (via {sup 14}C/{sup 12}C measurements). Recently, it has been shown that corals record evidence of large seasonal oscillations in {sup 14}C concentration of the ocean surface mixed layer, and that such oscillations are modulated by ENSO. These oscillations are related to seasonal changes in the surface wind velocity field, changes in the patterns of regional upwelling, as well as seasonal changes in the strength of the thermocline. High frequency AMS {sup 14}C analyses of corals shows that ENSO events can dramatically diminish the annual range in ocean mixed layer {sup 14}C concentration in this region. Our work on a coral from Vanuatu in the western equatorial Pacific also documents large seasonal changes in {sup 14}C concentration (3-5%) as well as ENSO modulation of these variations during the 82-83 ENSO event.

  10. Climatic controls on hurricane patterns: a 1200-y near-annual record from Lighthouse Reef, Belize.

    PubMed

    Denommee, K C; Bentley, S J; Droxler, A W

    2014-01-01

    Tropical cyclones (TCs) are powerful agents of destruction, and understanding climatic controls on TC patterns is of great importance. Over timescales of seasons to several decades, relationships among TC track, frequency, intensity and basin-scale climate changes are well documented by instrumental records. Over centuries to millennia, climate-shift influence on TC regimes remains poorly constrained. To better understand these relationships, records from multiple locations of TC strikes spanning millennia with high temporal resolution are required, but such records are rare. Here we report on a highly detailed sedimentary proxy record of paleo-TC strikes from the Blue Hole of Lighthouse Reef, Belize. Our findings provide an important addition to other high-resolution records, which collectively demonstrate that shifts between active and inactive TC regimes have occurred contemporaneously with shifts hemispheric-scale oceanic and atmospheric circulation patterns such as MDR SSTs and NAO mode, rather than with changes in local climate phenomena as has previously been suggested. PMID:24464265

  11. Climatic controls on hurricane patterns: a 1200-y near-annual record from Lighthouse Reef, Belize

    PubMed Central

    Denommee, K. C.; Bentley, S. J.; Droxler, A. W.

    2014-01-01

    Tropical cyclones (TCs) are powerful agents of destruction, and understanding climatic controls on TC patterns is of great importance. Over timescales of seasons to several decades, relationships among TC track, frequency, intensity and basin-scale climate changes are well documented by instrumental records. Over centuries to millennia, climate-shift influence on TC regimes remains poorly constrained. To better understand these relationships, records from multiple locations of TC strikes spanning millennia with high temporal resolution are required, but such records are rare. Here we report on a highly detailed sedimentary proxy record of paleo-TC strikes from the Blue Hole of Lighthouse Reef, Belize. Our findings provide an important addition to other high-resolution records, which collectively demonstrate that shifts between active and inactive TC regimes have occurred contemporaneously with shifts hemispheric-scale oceanic and atmospheric circulation patterns such as MDR SSTs and NAO mode, rather than with changes in local climate phenomena as has previously been suggested. PMID:24464265

  12. A lacustrine carbonate record of Holocene seasonality and climate

    USGS Publications Warehouse

    Wittkop, Chad A.; Teranes, Jane L.; Dean, Walter E.; Guilderson, Thomas P.

    2009-01-01

    Annually laminated (varved) Holocene sediments from Derby Lake, Michigan, display variations in endogenic calcite abundance reflecting a long-(millennial-scale) decrease in burial punctuated with frequent short- (decadal-scale) oscillations due to carbonate dissolution. Since 6000 cal yr B.P., sediment carbonate abundance has followed a decreasing trend while organic-carbon abundance has increased. The correlation between organic-carbon abundance and the sum of March-April-October-November insolation has an r2 value of 0.58. We interpret these trends to represent a precession-driven lengthening of the Holocene growing season that has reduced calcite burial by enhancing net annual organic-matter production and associated calcite dissolution. Correlations with regional paleoclimate records suggest that changes in temperature and moisture balance have impacted the distribution of short- oscillations in carbonate and organic-matter abundance superimposed on the precession-driven trends.

  13. A molecular organic carbon isotope record of miocene climate changes.

    PubMed

    Schoell, M; Schouten, S; Damsté, J S; de Leeuw, J W; Summons, R E

    1994-02-25

    The difference in carbon-13 ((13)C) contents of hopane and sterane biomarkers in the Monterey formation (Naples Beach, California) parallels the Miocene inorganic record of the change in (18)O (delta(18)O), reflecting the Miocene evolution from a well-mixed to a highly stratified photic zone (upper 100 meters) in the Pacific. Steranes (delta(13)C = 25.4 +/- 0.7 per mil versus the Pee Dee belemnite standard) from shallow photic-zone organisms do not change isotopically throughout the Miocene. In contrast, sulfur-bound C(35) hopanes (likely derived from bacterial plankton living at the base of the photic zone) have systematically decreasing (13)C concentrations in Middle and Late Miocene samples (delta(13)C = -29.5 to -31.5 per mil), consistent with the Middle Miocene formation of a carbon dioxide-rich cold water mass at the base of the photic zone. PMID:17831625

  14. A New Climate Data Record of Solar Spectral Irradiance from 1610 to Present

    NASA Astrophysics Data System (ADS)

    Coddington, O.; Lean, J.; Pilewskie, P.; Snow, M. A.; Lindholm, D. M.

    2015-12-01

    We present a climate data record of Solar Spectral Irradiance (SSI), with associated time and wavelength dependent uncertainties, from 1610 to the present. The data record was developed jointly by the University of Colorado at Boulder's Laboratory for Atmospheric and Space Physics (LASP) and the Naval Research Laboratory (NRL) as part of the National Oceanographic and Atmospheric Administration's (NOAA) National Centers for Environmental Information (NCEI) Climate Data Record (CDR) Program, where the data record, source code, and supporting documentation are archived. SSI is constructed from models that determine the changes from quiet Sun conditions arising from bright faculae and dark sunspots on the solar disk using linear regression of proxies of solar magnetic activity with observations from the SOlar Radiation and Climate Experiment (SORCE) Spectral Irradiance Monitor (SIM); the measurements are assumed to be reliable on solar rotational time scales. We extend the SSI record to longer time scales by reproducing the integral of the SSI with independent measurements of Total Solar Irradiance (TSI) measurements made by the SORCE Total Irradiance Monitor (TIM); TSI can be separately modeled to within TIM's measurement accuracy from solar rotational to solar cycle time scales. We discuss the model formulation, uncertainty estimates, and operational implementation and present comparisons of the modeled SSI with the measurement record and with other solar irradiance models. We also discuss future work to improve the Solar Irradiance Climate Data Record with new measurements from the Total and Spectral Solar Irradiance Sensor (TSIS), different proxy representations of sunspot darkening and facular brightening, including the improved composite record of Mg II index being developed as part of the European-led SOlar Irradiance Data exploitation (SOLID) project, and to expand the uncertainty estimates to include model assumptions.

  15. Last Interglacial climate variability recorded in sediments of Lake Ohrid (Albania/Macedonia)

    NASA Astrophysics Data System (ADS)

    Vogel, H.; Valsecchi, V.; Schouten, S.; Leng, M. J.; Wagner, B.; Sulpizio, R.; Zanchetta, G.; Lotter, A. F.

    2010-12-01

    Lake Ohrid, a transboundary lake shared by the former Yugoslav Republic of Macedonia and the Republic of Albania is with its likely Pliocene age considered to be the oldest existing lake in Europe. Since 2004 several sediment successions have been recovered from Lake Ohrid. The longest records cover the last glacial-interglacial cycle and reach back to MIS 6. Independent age control is given by radiocarbon dating and tephrochronology. These records allow insights on climatic and environmental evolution of the last interglacial in a region, which today is densely populated and highly vulnerable to climate change. We used a multiproxy approach to study climatic and environmental variability during the last interglacial. This approach combines novel molecular (TEX86, MBT/CBT) and established sedimentological, geochemical and paleoecological tools. These combined data imply that the last interglacial at Lake Ohrid was preceded by an interstadial period between c. 133 and 131 ka that was followed by a stadial centred at c. 130 ka and characterized by a marked vegetation shift to more steppic elements around the lake. Subsequently, temperatures rose steadily from c. 129 to 122 ka. From c. 122 ka temperatures declined gradually. A sudden drop in temperatures starting at about 116 ka probably marks the end of the last interglacial period at Lake Ohrid. A comparison of highest temperatures during the Holocene and the last interglacial points to 2-3 °C higher temperatures during the last interglacial. A temperature increase in the same order is predicted by climate models for this region implying that last interglacial climatic and environmental conditions as recorded in Lake Ohrids sediments could provide a relatively good analogue for the future. However, longer records from this area are needed to gain a better understanding of natural climate variability during interglacials with a different setting of orbital parameters. In order to recover longer records extending

  16. Climatic Change over the 'Third Pole' from Long Tree-Ring Records

    NASA Astrophysics Data System (ADS)

    Cook, E.

    2011-12-01

    Climatic change over the Greater Himalayas and Tibetan Plateau, the 'Third Pole' of the world, is of great concern now as the Earth continues to warm at an alarming rate. While future climatic change over this region and its resulting impacts on humanity and the environment are difficult to predict with much certainty, knowing how climate has varied in the past can provide both an improved understanding of the range of variability and change that could occur in the future and the necessary context for assessing recent observed climatic change there. For this purpose, one of the best natural archives of past climate information available for study of the Third Pole environment is the changing pattern of annual ring widths found in long tree-ring chronologies. The forests of the Third Pole support many long-lived tree species, with some having life spans in excess of 1,000 years. This natural resource is steadily dwindling now due to continuing deforestation caused by human activity, but there is still enough remaining forest cover to produce a detailed network of long tree-ring chronologies for study of climate variability and change covering the past several centuries. The tree-ring records provide a mix of climate information, including that related to both temperature and precipitation. Examples of long drought-sensitive tree-ring records from the more arid parts of the Karakoram and Tibetan Plateau will be presented, along with records that primarily reflect changing temperatures in moister environments such as in Bhutan. Together they provide a glimpse of how climate of the Third Pole has changed over the past several centuries, the range of natural variability that could occur in the future independent of changes caused by greenhouse warming, and how changes during the latter part of the 20th century period of rapid global warming compare to the past.

  17. An 8700 Year Record of Holocene Climate Variability from the Yucatan Peninsula

    NASA Astrophysics Data System (ADS)

    Wahl, D.; Byrne, R.; Anderson, L.

    2013-12-01

    Our understanding of Holocene climate change in the Maya lowlands of Central America has improved significantly during the last several decades thanks to the development of proxy climate records from lake cores and speleothems. One important finding is that longer-term climate changes (i.e., millennial scale) were driven primarily by precessional forcing; less clear, however, are the causes of abrupt shifts and higher frequency (centennial to decadal) change recognized in many Holocene climate reconstructions. The mechanisms driving climate change on these time scales have been difficult to identify in the region, in part because the Yucatan peninsula is influenced by climatic conditions linked to both the tropical Atlantic and Pacific oceans. Additional complications arise from the development of dense human populations following the initial introduction of agriculture ~5000 cal yr BP, which had significant impact on the environment as a whole. Here we present the results of analyses (stable isotope, pollen, magnetic susceptibility, and physical properties) of a 7.25 m sediment core from Lago Puerto Arturo, a closed basin lake in the northern Peten, Guatemala. An age-depth model, based on 6 AMS radiocarbon determinations and created using CLAM, indicates the record extends to 8700 cal yr BP. Proxy data suggest that, similar to other low latitude sites, millennial scale climate at Lago Puerto Arturo was driven by changes in insolation. Higher frequency variability is associated with El Niño/Southern Oscillation (ENSO) and North Atlantic Oscillation (NAO) dynamics, reflecting latitudinal shifts in the Intertropical Convergence Zone in both the tropical North Atlantic and North Pacific. Solar forcing may also play a role in short-term climate change. The pollen and isotope records show that the entire period of prehispanic settlement and agricultural activity, i.e. ~5000-1000 cal yr B.P., was characterized by relatively dry conditions compared to before or after.

  18. Sampling Impacts on the NVAP-M Global Water Vapor Climate Data Record

    NASA Astrophysics Data System (ADS)

    Vonder Haar, T. H.; Forsythe, J. M.; Cronk, H. Q.

    2015-12-01

    Atmospheric water vapor is a fundamental ingredient both for regulating climate as a greenhouse gas and as a necessary precursor for high impact weather events such as heavy precipitation. Water vapor concentration varies geographically because of its close linkage with surface temperature and as a component of synoptic and mesoscale weather systems. Satellite observations provide the only means to quantify the global occurrence and variability of water vapor. In common with other long-term climate data records such as clouds and precipitation, intercalibrating and blending diverse measurements of water vapor to create a consistent record through time is a challenge. The NASA Making Earth Science Data Records for Research Environments (MEaSUREs) program supported the development of the NASA Water Vapor Project (NVAP-M) dataset. The dataset was released to the science community in 2013 via the NASA Langley Atmospheric Science Data Center. The dataset is a global (land and ocean) water vapor dataset created by merging multiple satellite infrared and microwave sources of atmospheric water vapor along with surface data to form global gridded fields of total and layered precipitable water vapor. NVAP-M spans 22 years (1988-2009) of data. The challenges in creating this multisensor, multidecadal satellite-driven climate data record are illustrative of challenges for all satellite climate data records. While advances in sensor intercalibration and retrieval algorithms have improved the quality of the global water vapor climate data record, uncertainties arise due to sampling biases of the input sensors. These biases are particularly evident on a regional scale, in cloudy regions or over desert surfaces. The changing mixture of sensors with varying sensitivity to clear/cloudy, land/ocean and even day/night conditions can lead to different results on trends and variability of water vapor. We explore this variability via the NVAP-M data set. Connections and collaborations

  19. Records from Lake Qinghai: Holocene climate history of Northeastern Tibetan Plateau linking to global change

    NASA Astrophysics Data System (ADS)

    An, Z.; Colman, S.; Zhou, W.; Brown, E.; Li, X.; Jull, T.; Wang, S.; Liu, W.; Sun, Y.; Lu, X.; Song, Y.; Chang, H.; Cai, Y.; Xu, H.; Wang, X.; Liu, X.; Wu, F.; Han, Y.; Cheng, P.; Ai, L.; Wang, Z.; Qiang, X.; Shen, J.; Zhu, Y.; Wu, Z.; Liu, X.

    2008-12-01

    Lake Qinghai (99°36'-100°16'E, 36°32'-37°15'N ) of the north eastern margin of Tibet Plateau is the largest inland lake of China. It sits on the transitional zone of Asian monsoon- arid areas, receives influences of Asian monsoons and Westerlies, thus sensitive to global climate changes. Although previous studies had investigated Holocene climate change of Lake Qinghai area, it is rare to see precise Holocene climatic sequences of Lake Qinghai, nor in-depth discussions on controlling factors of Lake Qinghai climate changes. In Year 2005, with support from ICDP, Chinese Academy of Sciences (CAS), Chinese Ministry of Science and Technology (MOST) and National Science Foundation of China (NSFC), Drilling, Observation and Sampling of the Earths Continental Crust Corporation (DOSECC) and Institute of Earth Environment, Chinese Academy of Sciences (IEECAS) took a series of shallows cores from the southern basin of Lake Qinghai. West sub-basin sediments display Holocene lacustrine feature for the upper 5m, while the 5-18m are interbeded sediments of shallow lake, eolian-lacustrine and eolian loess. Chinese and US scientists with support from NSFC, MOST, CAS and NSF analysed 1F core from west sub-basin depocenter of the south basin with multiple physical, chemical, biological approaches. By comparing with modern process observation records, we obtained proxies that respectfully reflect precipitation, temperature and lake salinity changes, etc., reconstructed high resolution time sequences of magnetic susceptibility, colour scale, grain size, Corg, C/N, δ13Corg, carbonate, δ13C and δ18O of carbonate and ostracodes, elements, char-soot,Uk'37 and %C37:4 as well as pollen of the last 13Ka. They indicate the climatic change history of Lake Qinghai since past 13Ka, and agreeable evidences are found from adjacent tree ring and stalagmite records. Comparison of Lake Qinghai Holocene climate change sequence with those from high altitude ice core, stalagmites and ocean

  20. A molecular organic carbon isotope record of miocene climate changes

    SciTech Connect

    Schoell, M. ); Schouten, S.; Sinninghe Damste', J.S.; Leeuw, J.W. de ); Summons, R.E. )

    1994-02-25

    The difference in carbon-13 ([sup 13]C) contents of hopane and sterane biomarkers in the Monterey formation (Naples Beach, California) parallels the Miocene inorganic record of the change in [sup 18]O ([delta][sup 18]O), reflecting the Miocene evolution from a well-mixed to a highly stratified photic zone (upper 100 meters) in the Pacific. Steranes ([delta][sup 13]C = 25.4 [+-] 0.7 per mil versus the Pee Dee belemnite standard) from shallow photic-zone organisms do not change isotopically throughout the Miocene. In contrast, sulfur-bound C[sub 35] hopanes (likely derived from bacterial plankton living at the base of the photic zone) have systematically decreasing [sup 13]C concentrations in Middle and Late Miocene samples ([delta][sup 13]C = 29.5 to [minus]31.5 per mil), consistent with the Middle Miocene formation of a carbon dioxide-rich cold water mass at the base of the photic zone.

  1. A long-term Northern Hemisphere snow cover extent data record for climate studies and monitoring

    NASA Astrophysics Data System (ADS)

    Estilow, T. W.; Young, A. H.; Robinson, D. A.

    2015-06-01

    This paper describes the long-term, satellite-based visible snow cover extent National Oceanic and Atmospheric Administration (NOAA) climate data record (CDR) currently available for climate studies, monitoring, and model validation. This environmental data product is developed from weekly Northern Hemisphere snow cover extent data that have been digitized from snow cover maps onto a Cartesian grid draped over a polar stereographic projection. The data have a spatial resolution of 190.6 km at 60° latitude, are updated monthly, and span the period from 4 October 1966 to the present. The data comprise the longest satellite-based CDR of any environmental variable. Access to the data is provided in Network Common Data Form (netCDF) and archived by NOAA's National Climatic Data Center (NCDC) under the satellite Climate Data Record Program (doi:10.7289/V5N014G9). The basic characteristics, history, and evolution of the data set are presented herein. In general, the CDR provides similar spatial and temporal variability to its widely used predecessor product. Key refinements included in the CDR improve the product's grid accuracy and documentation and bring metadata into compliance with current standards for climate data records.

  2. Coral oxygen isotope records of interdecadal climate variations in the South Pacific Convergence Zone region

    NASA Astrophysics Data System (ADS)

    Bagnato, Stefan; Linsley, Braddock K.; Howe, Stephen S.; Wellington, Gerard M.; Salinger, Jim

    2005-06-01

    The South Pacific Convergence Zone (SPCZ), a region of high rainfall, is a major feature of subtropical Southern Hemisphere climate and contributes to and interacts with circulation features across the Pacific, yet its past temporal variability and forcing remain only partially understood. Here we compare coral oxygen isotopic (δ18O) series (spanning A.D. 1997-1780 and A.D. 2001-1776) from two genera of hermatypic corals in Fiji, located within the SPCZ, to examine the fidelity of these corals in recording climate change and SPCZ interdecadal dynamics. One of these coral records is a new 225-year subannually resolved δ18O series from the massive coral Diploastreaheliopora. Diploastrea's use in climate reconstructions is still relatively new, but this coral has shown encouragingly similar interannual variability to Porites, the coral genus most commonly used in Pacific paleoclimate studies. In Fiji we observe that interdecadal δ18O variance is also similar in these two coral genera, and Diploastrea contains a larger-amplitude interdecadal signal that more closely tracks instrumental-based indices of Pacific interdecadal climate change and the SPCZ than Porites. Both coral δ18O series record greater interdecadal variability from ˜1880 to 1950, which is consistent with the observations of Folland et al. (2002), who reported higher variability in SPCZ position before 1945. These observations indicate that Diploastrea will likely provide a significant new source of long-term climate information from the SPCZ region.

  3. Biogeochemistry of carbonates: recorders of past oceans and climate.

    PubMed

    Rickaby, Rosalind E M; Schrag, Daniel P

    2005-01-01

    Trace metal proxies bound within the calcium carbonate tests of oceanic organisms provide a unique insight into how the climate system works on timescales which span eight orders of magnitude, from annual to hundreds of millions of years. Whilst the motivation for developing these proxies was the idea that thermodynamic equilibria control the chemistry during precipitation, in reality the application of trace metal proxies relies upon empirical calibration. Such calibration can be applied to a wide range of environmental reconstructions, but more accurate application of proxies requires a mechanistic understanding of the biomineralization process. The partitioning of trace metals into biogenic carbonates reflects to some extent the same pattern as an inorganic crystal, but there is an additional selectivity and differing environmental sensitivity to, e.g., temperature, which confirms that biochemical processes also play a role in the uptake and assembly of ions into a crystal. Different organisms display differing degrees of biological control on their carbonate chemistry. Aragonitic coral chemistry is most similar to inorganic precipitation from seawater whilst coccolithophores are most different, and these contrasts correlate with the degree of control of the organism over its biomineralization. Selectivity between Ca and trace metals during biomineralization arises during transport by pumps, channels, or nucleation upon an organic matrix. The biological selectivity of the transporters and matrix is strikingly similar in its base chemistry to the selective assembly of ions into a crystal. In each case, the selectivity between Ca2+ and trace metals derives from the balance between the energy required for dehydration of the hexaaqua complex of the cation, and the energy released from the new coordination geometry of binding with either carbonyl oxygen from polysaccharides or amino acids, or carbonate oxygen in the crystal. This is a speculative idea, but with some

  4. Detailed glaciochemical investigations in southern Victoria Land - a proxy climatic record

    SciTech Connect

    Mayewski, P.A.

    1987-09-01

    Local accumulation-basins in the Transantarctic Mountains possess sites suitable for recovering ice-core records that are valuable for studying climate change. These sites are also unique, because they are close to the sites of other ice-core studies and to areas with established terrestrial records. The objective is to study a snowpit in detail and collect ice cores in southern Victoria Land; this work will be similar to the investigations that the authors has conducted in south Greenland and in the Dominion Range near the Beardmore Glacier. The proposed sites are in Convoy, Asgard, and Royal Society ranges. The authors will select one site at which he will recover two ice cores, each approximately 200 to 300 meters in depth. Samples will be analyzed for major anions (chloride, sulfate, nitrate, fluoride) and cations (sodium, potassium, magnesium, ammonium, silicate), total acidity, conductivity, density, and core stratigraphy with dating provided by cross-calibration of all of the preceding plus total beta-activity, lead-210, oxygen isotopes, and microparticles. This investigation will yield a detailed record of several thousand years of glacial history, climate change, and volcanic activity for southern Victoria Land. This record will be compared to existing terrestrial records to add necessary detail and to other global ice-core records to assess global climatic change. It will also help to document volcanic activity for Mount Erebus as well as other volcanos in the Southern Hemisphere and possibly some in the Northern Hemisphere. With this record, the author will be able to evaluate the influence of volcanic and solar activity on climate as well as add greatly to the understanding of the chemistry of the global atmosphere.

  5. Late to middle Pleistocene climate variability recorded in stalagmites from Sofular Cave, Northern Turkey

    NASA Astrophysics Data System (ADS)

    Fleitmann, D.; Cheng, H.; Edwards, R. L.; Badertscher, S.; Tüysüz, O.

    2012-04-01

    The modern climate in Turkey and the eastern Mediterranean is strongly affected by two major climate systems; the North Atlantic/Siberian pressure system in winter and the Indian monsoon in summer. Turkey is thus ideally situated to study how and to what extent both systems were dynamically linked during the Holocene and Pleistocene. Our current knowledge of continental climate variability in Turkey relies almost entirely on lake records with only a few extending back to the Last Glacial Maximum and beyond. Another source of information on Pleistocene and Holocene climate variability is speleothems, which can be found in caves throughout Turkey. Here we present composite stalagmite oxygen and carbon isotope records from Sofular Cave located at the Black Sea coast in north-western Turkey, which cover the last 670.000 discontinuously. Uranium-series dates with unprecedented small age uncertainties of only 0.25-2% and highly resolved isotope profiles allow us to (1) identify the climatic impacts of Dansgaard-Oeschger and Heinrich events, (2) compare climatic and environmental conditions during different interglacial and glacial periods (Marine Isotope Stages 1-7, 9, 13 and 15) and (3) reveal changes in the hydrological state of the Black Sea in unprecedented detail.

  6. A 0.6 million year record of millennial-scale climate variability in the tropics

    NASA Astrophysics Data System (ADS)

    Gibson, Kelly Ann; Peterson, Larry C.

    2014-02-01

    A ~600 kyr long scanning X-ray fluorescence record of redox variability from the Cariaco Basin, Venezuela, provides insight into rapid climate change in the tropics over the past five glacial-interglacial cycles. Variations in the sediment accumulation of the redox-sensitive element molybdenum (Mo) can be linked to changes in Intertropical Convergence Zone migration and reveal that millennial-scale variability is a persistent feature of tropical climate over the past 600 kyr, including during periods of interglacial warmth. This new record supports the idea that high-frequency tropical climate variability is not controlled solely by ice volume changes, with implications for the role of high-latitude forcing of Intertropical Convergence Zone position and tropical hydrology on millennial timescales.

  7. Climate Change Detection in the UTLS with the GPS Radio Occultation Record

    NASA Astrophysics Data System (ADS)

    Steiner, A. K.; Kirchengast, G.; Lackner, B. C.; Hegerl, G. C.; Pirscher, B.; Foelsche, U.

    2009-12-01

    Radio Occultation (RO) based on signals from Global Positioning System (GPS) satellites provides a new climate record of high quality and vertical resolution in the upper troposphere and lower stratosphere (UTLS). RO data are considered a climate benchmark data type since they are based on timing with precise atomic clocks and tied to the international definition of the second. Long-term stability and the consistency of RO data stemming from different satellites (without need for inter-calibration) make RO well suited for climate change detection. RO data are available on a continuous basis from Sep 2001 to Sep 2008 from the CHAMP satellite and intermittent periods of observations from the GPS/Met proof-of-concept mission exist in the years 1995-1997, with sufficient data only for Oct 1995 and Feb 1997. We present a climate change detection study based on monthly mean zonal mean RO climatologies in the UTLS region within 9-25 km (300-30 hPa) where we use different detection methods. An optimal fingerprinting technique is applied to the whole record of RO accessible parameters refractivity, geopotential height, and temperature to detect a forced climate signal. Three representative global climate models of the 4th Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) are employed to estimate natural climate variability using pre-industrial control runs. The response pattern to the external forcings is presented by an ensemble mean of the models' A2 and B1 scenario runs. Optimal fingerprinting shows that a climate change signal can be detected in the RO refractivity and in the RO temperature record (90 % significance level). Furthermore, standard and multiple linear regression is applied to temperature time series for February (1997 and 2002-2008) and for October (1995 and 2001-2007), taking RO errors into account. In the tropics, we also investigate the influence of stratospheric quasi-biennial oscillation (QBO) and tropospheric El Nino

  8. The new climate data record of total and spectral solar irradiance: Current progress and future steps

    NASA Astrophysics Data System (ADS)

    Coddington, Odele; Lean, Judith; Rottman, Gary; Pilewskie, Peter; Snow, Martin; Lindholm, Doug

    2016-04-01

    We present a climate data record of Total Solar Irradiance (TSI) and Solar Spectral Irradiance (SSI), with associated time and wavelength dependent uncertainties, from 1610 to the present. The data record was developed jointly by the Laboratory for Atmospheric and Space Physics (LASP) at the University of Colorado Boulder and the Naval Research Laboratory (NRL) as part of the National Oceanographic and Atmospheric Administration's (NOAA) National Centers for Environmental Information (NCEI) Climate Data Record (CDR) Program, where the data record, source code, and supporting documentation are archived. TSI and SSI are constructed from models that determine the changes from quiet Sun conditions arising from bright faculae and dark sunspots on the solar disk using linear regression of proxies of solar magnetic activity with observations from the SOlar Radiation and Climate Experiment (SORCE) Total Irradiance Monitor (TIM), Spectral Irradiance Monitor (SIM), and SOlar Stellar Irradiance Comparison Experiment (SOLSTICE). We show that TSI can be separately modeled to within TIM's measurement accuracy from solar rotational to solar cycle time scales and we assume that SSI measurements are reliable on solar rotational time scales. We discuss the model formulation, uncertainty estimates, and operational implementation and present comparisons of the modeled TSI and SSI with the measurement record and with other solar irradiance models. We also discuss ongoing work to assess the sensitivity of the modeled irradiances to model assumptions, namely, the scaling of solar variability from rotational-to-cycle time scales and the representation of the sunspot darkening index.

  9. Climate reconstruction from pollen and δ13C records using inverse vegetation modeling - Implication for past and future climates

    NASA Astrophysics Data System (ADS)

    Hatté, C.; Rousseau, D.-D.; Guiot, J.

    2009-04-01

    An improved inverse vegetation model has been designed to better specify both temperature and precipitation estimates from vegetation descriptions. It is based on the BIOME4 vegetation model and uses both vegetation δ13C and biome as constraints. Previous inverse models based on only one of the two proxies were already improvements over standard reconstruction methods such as the modern analog since these did not take into account some external forcings, for example CO2 concentration. This new approach makes it possible to describe a potential "isotopic niche" defined by analogy with the "climatic niche" theory. Boreal and temperate biomes simulated by BIOME4 are considered in this study. We demonstrate the impact of CO2 concentration on biome existence domains by replacing a "most likely biome" with another with increased CO2 concentration. Additionally, the climate imprint on δ13C between and within biomes is shown: the colder the biome, the lighter its potential isotopic niche; and the higher the precipitation, the lighter the δ13C. For paleoclimate purposes, previous inverse models based on either biome or δ13C did not allow informative paleoclimatic reconstructions of both precipitation and temperature. Application of the new approach to the Eemian of La Grande Pile palynological and geochemical records reduces the range in precipitation values by more than 50% reduces the range in temperatures by about 15% compared to previous inverse modeling approaches. This shows evidence of climate instabilities during Eemian period that can be correlated with independent continental and marine records.

  10. Exceptional record of mid-Pleistocene vertebrates helps differentiate climatic from anthropogenic ecosystem perturbations.

    PubMed

    Barnosky, Anthony D; Bell, Christopher J; Emslie, Steven D; Goodwin, H Thomas; Mead, Jim I; Repenning, Charles A; Scott, Eric; Shabel, Alan B

    2004-06-22

    Mid-Pleistocene vertebrates in North America are scarce but important for recognizing the ecological effects of climatic change in the absence of humans. We report on a uniquely rich mid-Pleistocene vertebrate sequence from Porcupine Cave, Colorado, which records at least 127 species and the earliest appearances of 30 mammals and birds. By analyzing >20,000 mammal fossils in relation to modern species and independent climatic proxies, we determined how mammal communities reacted to presumed glacial-interglacial transitions between 1,000,000 and 600,000 years ago. We conclude that climatic warming primarily affected mammals of lower trophic and size categories, in contrast to documented human impacts on higher trophic and size categories historically. Despite changes in species composition and minor changes in small-mammal species richness evident at times of climatic change, overall structural stability of mammal communities persisted >600,000 years before human impacts. PMID:15197254

  11. Climatic changes near the Great Lakes inferred from 141 year ice records

    USGS Publications Warehouse

    Assel, Raymond A.; Robertson, Dale M.

    1992-01-01

    Freeze-up and break-up dates and duration of ice cover for lakes and rivers represent an integration of weather conditions prior to the specified event(s). Changes in mean ice conditions may be used as quantitative indicators of climatic changes if long homogenous ice records are accompanied by sufficiently homogenous air temperature records to calibrate the changes in mean ice cover in terms of climatic variables. Historical ice records dating back to 1855 are available for Lake Mendota, WI (located on the southwestern side of Lake Michigan) and back to 1851 for Grand Traverse Bay, MI (located on the northeastern side of Lake Michigan). Changes in the mean ice cover of these two systems were used to describe changes in fall, winter, and spring air temperatures in the area near the Great Lakes during the past 141 years. 

  12. Plio-Pleistocene climate sensitivity evaluated using high-resolution CO2 records.

    PubMed

    Martínez-Botí, M A; Foster, G L; Chalk, T B; Rohling, E J; Sexton, P F; Lunt, D J; Pancost, R D; Badger, M P S; Schmidt, D N

    2015-02-01

    Theory and climate modelling suggest that the sensitivity of Earth's climate to changes in radiative forcing could depend on the background climate. However, palaeoclimate data have thus far been insufficient to provide a conclusive test of this prediction. Here we present atmospheric carbon dioxide (CO2) reconstructions based on multi-site boron-isotope records from the late Pliocene epoch (3.3 to 2.3 million years ago). We find that Earth's climate sensitivity to CO2-based radiative forcing (Earth system sensitivity) was half as strong during the warm Pliocene as during the cold late Pleistocene epoch (0.8 to 0.01 million years ago). We attribute this difference to the radiative impacts of continental ice-volume changes (the ice-albedo feedback) during the late Pleistocene, because equilibrium climate sensitivity is identical for the two intervals when we account for such impacts using sea-level reconstructions. We conclude that, on a global scale, no unexpected climate feedbacks operated during the warm Pliocene, and that predictions of equilibrium climate sensitivity (excluding long-term ice-albedo feedbacks) for our Pliocene-like future (with CO2 levels up to maximum Pliocene levels of 450 parts per million) are well described by the currently accepted range of an increase of 1.5 K to 4.5 K per doubling of CO2. PMID:25652996

  13. A maturity model for assessing the completeness of climate data records

    NASA Astrophysics Data System (ADS)

    Bates, John J.; Privette, Jeffrey L.

    2012-10-01

    The demand for climate information, with long observational records spanning decades to centuries and the information's broad application for decision making across many socioeconomic sectors, requires that geophysicists adopt more rigorous processes for the sustained production of climate data records (CDRs). Such processes, methods, and standards are more typically found in the systems engineering community and have not generally been adopted in the climate science community. We propose the use of a maturity matrix for climate data records that characterizes the process of moving from a basic research product (e.g., raw data and initial product) to a sustained and routinely generated product (e.g., a quality-controlled homogenized data set). This model of increasing product and process maturity is similar to NASA's technical readiness levels for flight hardware and instrumentation and the software industry's capability maturity model. Over time, engineers who have worked on many projects developed a set of best practices that identified the processes required to optimize cost, schedule, and risk. In the NASA maturity model, they identified steps in technology readiness, denoted as the technology readiness level (TRL). TRL 1 occurs when basic research has taken the first steps toward application. TRL 9 is when a technology has been fully proven to work consistently for the intended purpose and is operational.

  14. Development, Production and Validation of the NOAA Solar Irradiance Climate Data Record

    NASA Astrophysics Data System (ADS)

    Coddington, O.; Lean, J.; Pilewskie, P.; Snow, M. A.; Lindholm, D. M.

    2015-12-01

    A new climate data record of Total Solar Irradiance (TSI) and Solar Spectral Irradiance (SSI), including source code and supporting documentation is now publicly available as part of the National Oceanographic and Atmospheric Administration's (NOAA) National Centers for Environmental Information (NCEI) Climate Data Record (CDR) Program. Daily and monthly averaged values of TSI and SSI, with associated time and wavelength dependent uncertainties, are estimated from 1882 to the present with yearly averaged values since 1610, updated quarterly for the foreseeable future. The new Solar Irradiance Climate Data Record, jointly developed by the University of Colorado at Boulder's Laboratory for Atmospheric and Space Physics (LASP) and the Naval Research Laboratory (NRL), is constructed from solar irradiance models that determine the changes from quiet Sun conditions when bright faculae and dark sunspots are present on the solar disk. The magnitudes of the irradiance changes that these features produce are determined from linear regression of the proxy Mg II index and sunspot area indices against the approximately decade-long solar irradiance measurements made by instruments on the SOlar Radiation and Climate Experiment (SORCE) spacecraft. We describe the model formulation, uncertainty estimates, operational implementation and validation approach. Future efforts to improve the uncertainty estimates of the Solar Irradiance CDR arising from model assumptions, and augmentation of the solar irradiance reconstructions with direct measurements from the Total and Spectral Solar Irradiance Sensor (TSIS: launch date, July 2017) are also discussed.

  15. A rock-magnetic record from Lake Baikal, Siberia: Evidence for Late Quaternary climate change

    USGS Publications Warehouse

    Peck, J.A.; King, J.W.; Colman, Steven M.; Kravchinsky, V.A.

    1994-01-01

    Rock-magnetic measurements of sediment cores from the Academician Ridge region of Lake Baikal, Siberia show variations related to Late Quaternary climate change. Based upon the well-dated last glacial-interglacial transition, variations in magnetic concentration and mineralogy are related to glacial-interglacial cycles using a conceptual model. Interglacial intervals are characterized by low magnetic concentrations and a composition that is dominated by low coercivity minerals. Glacial intervals are characterized by high magnetic concentrations and increased amounts of high coercivity minerals. The variation in magnetic concentration is consistent with dilution by diatom opal during the more productive interglacial periods. We also infer an increased contribution of eolian sediment during the colder, windier, and more arid glacial conditions when extensive loess deposits were formed throughout Europe and Asia. Eolian transport is inferred to deliver increased amounts of high coercivity minerals as staining on eolian grains during the glacial intervals. Variations in magnetic concentration and mineralogy of Lake Baikal sediment correlate to the SPECMAP marine oxygen-isotope record. The high degree of correlation between Baikal magnetic concentration/mineralogy and the SPECMAP oxygen-isotope record indicates that Lake Baikal sediment preserves a history of climate change in central Asia for the last 250 ka. This correlation provides a method of estimating the age of sediment beyond the range of the radiocarbon method. Future work must include providing better age control and additional climate proxy data, thereby strengthening the correlation of continental and marine climate records. ?? 1994.

  16. Ice Core Recorded Climate changes on the Tibetan Plateau in the past 2000 years

    NASA Astrophysics Data System (ADS)

    Yao, T.; Yao Tandong

    2011-12-01

    Climate history on the Tibetan Plateau in the past 2000 years has been profusely studied using various proxies. Ice cores have been drilled on the Plateau since last century, with four cores systematically studied and widely reported as the Dasuopu (in Xixabangma on south Plateau), Guliya (in the west Kunlun Mt. on northwest Plateau), Puruogangri (in central Plateau), and Dunde (in Mt Qilian on north Plateau) ice cores. Different geographical locations of those four ice cores give rise to distinct climate histories, with the Dasuopu ice core representing variance of the Indian monsoon influence, the Guliya and Dunde ice cores representing that of the westerlies, and the Puruogangri ice core representing the interaction of both large-scale circulation systems. Despite different dominative circulation processes, study of modern delta-18O in precipitation suggests a positive correlation between delta-18O and temperature, thus confirming the representativeness of long-term delta-18O in ice cores of paleo-temperature. Each ice core record represents regional temperature variation, while comparison of those records highlight the synchronicity of significant climate events in the past 2000 years, including the Medieval Warm Period, Little Ice Age, and the 20th century warming. Besides, solar isolation is shown as the dominant factor over temperature changes on the Plateau, while variation of ENSO bears significantly on precipitation and snow accumulation on Tibetan glaciers. Recent studies of newly drilled ice cores in southeast Plateau reveals close relationship of temperature with bacteria variability, implying potential effect of global warming on bacteria activity. They also demonstrate significant effect of black carbon on glacial melting, suggesting increased influence of human activities on the southeast Plateau. With the widely distributed ice cores acquired, a composite of ice core records on the Plateau is in urgent need to demonstrate climate variation for the

  17. Uranium-series dating of sediments from Searles Lake: Differences between continental and marine climate records

    USGS Publications Warehouse

    Bischoff, J.L.; Rosenbauer, R.J.; Smith, G.I.

    1985-01-01

    One of the major unresolved questions in Pleistocene paleoclimatology has been whether continental climatic transitions are consistent with the glacial ??18O marine record. Searles Lake in California, now a dry salt pan, is underlain by sediment layers deposited in a succession of lakes whose levels and salinities have fluctuated in response to changes in climate over the last 3 ?? 106 years. Uranium-series dates on the salt beds range from 35 ?? 103 to 231 ?? 103 years. This range of dates allows identification of lake-sediment horizons that are time correlatives of the boundaries of marine isotope stages from the recent 3/4 boundary back to the 8/9 boundary. The 5/6 boundary coincided with a deepening of the lake, but the analogous 1/2 boundary coincided with desiccation. The 3/4, 4/5, 6/7, 7/8, and 8/9 boundaries correspond in age to horizons that record little or no change in sedimentation or climate. These hydrologic results demonstrate that the continental paleoclimate record at this mid-latitude site does not mimic the marine record.

  18. Uranium-series dating of sediments from searles lake: differences between continental and marine climate records.

    PubMed

    Bischoff, J L; Rosenbauer, R J; Smith, G I

    1985-03-01

    One of the major unresolved questions in Pleistocene paleoclimatology has been whether continental climatic transitions are consistent with the glacial delta(18)O marine record. Searles Lake in California, now a dry salt pan, is underlain by sediment layers deposited in a succession of lakes whose levels and salinities have fluctuated in response to changes in climate over the last 3 x 10(6) years. Uraniumseries dates on the salt beds range from 35 x 10(3) to 231x 10(3) years. This range of dates allows identification of lake-sediment horizons that are time correlatives of the boundaries of marine isotope stages from the recent 3/4 boundary back to the 8/9 boundary. The 5/6 boundary coincided with a deepening of the lake, but the analogous 1/2 boundary coincided with desiccation. The 3/4, 4/5, 6/7, 7/8, and 8/9 boundaries correspond in age to horizons that record little or no change in sedimentation or climate. These hydrologic results demonstrate that the continental paleoclimate record at this mid-latitude site does not mimic the marine record. PMID:17757864

  19. A 2000 year varve-based climate record from the central Brooks Range, Alaska

    SciTech Connect

    Bird, B.W.; Abbott, M.B.; Finney, B.P.; Kutchko, Barbara

    2009-01-01

    Varved minerogenic sediments from glacial-fed Blue Lake, northern Alaska, are used to investigate late Holocene climate variability. Varve thickness measurements track summer temperature recorded at Atigun Pass, located 41 km east at a similar elevation (r2 = 0.31, P = 0.08). Results indicate that climate in the Brooks Range from 10 to 730 AD (varve year) was warm with precipitation inferred to be higher than during the twentieth century. The varve-temperature relationship for this period was likely compromised and not used in our temperature reconstruction because the glacier was greatly reduced, or absent, exposing sub-glacial sediments to erosion from enhanced precipitation.

  20. GCOS reference upper air network (GRUAN): Steps towards assuring future climate records

    NASA Astrophysics Data System (ADS)

    Thorne, P. W.; Vömel, H.; Bodeker, G.; Sommer, M.; Apituley, A.; Berger, F.; Bojinski, S.; Braathen, G.; Calpini, B.; Demoz, B.; Diamond, H. J.; Dykema, J.; Fassò, A.; Fujiwara, M.; Gardiner, T.; Hurst, D.; Leblanc, T.; Madonna, F.; Merlone, A.; Mikalsen, A.; Miller, C. D.; Reale, T.; Rannat, K.; Richter, C.; Seidel, D. J.; Shiotani, M.; Sisterson, D.; Tan, D. G. H.; Vose, R. S.; Voyles, J.; Wang, J.; Whiteman, D. N.; Williams, S.

    2013-09-01

    The observational climate record is a cornerstone of our scientific understanding of climate changes and their potential causes. Existing observing networks have been designed largely in support of operational weather forecasting and continue to be run in this mode. Coverage and timeliness are often higher priorities than absolute traceability and accuracy. Changes in instrumentation used in the observing system, as well as in operating procedures, are frequent, rarely adequately documented and their impacts poorly quantified. For monitoring changes in upper-air climate, which is achieved through in-situ soundings and more recently satellites and ground-based remote sensing, the net result has been trend uncertainties as large as, or larger than, the expected emergent signals of climate change. This is more than simply academic with the tropospheric temperature trends issue having been the subject of intense debate, two international assessment reports and several US congressional hearings. For more than a decade the international climate science community has been calling for the instigation of a network of reference quality measurements to reduce uncertainty in our climate monitoring capabilities. This paper provides a brief history of GRUAN developments to date and outlines future plans. Such reference networks can only be achieved and maintained with strong continuing input from the global metrological community.

  1. Decadal-scale variability in climate proxy records: a search for tidal and solar forcing

    NASA Astrophysics Data System (ADS)

    Berger, W.; Paetzold, J.; Wefer, G.

    2003-04-01

    Decadal-scale climate- and ocean variability is an unsolved problem. The geologic record holds a number of clues as to possible forcing functions; useful proxy series are in ice cores, corals, biogenic deposits in anaerobic basins, marine varves and small turbidites, in the sea and in lakes. Certain decadal-scale cycles seem to occur more commonly than others, and in a number of records with an entirely different pedigree, suggesting effects from outside forcing. If we assume that both solar forcing and tidal forcing play some role (as supported by spectra from corals and varves), we should expect interference between the respective forcing functions. From such interference, we can calculate the most likely periods to be found. Analysis of an 800-y coral record from Bermuda suggests that such interference periods are expressed in this proxy record.

  2. Solving the Global Climate Monitoring Problem in the Atmosphere: Towards SI-tied Climate Records with Integrated Uncertainty Propagation

    NASA Astrophysics Data System (ADS)

    Kirchengast, G.; Schwaerz, M.; Fritzer, J.; Schwarz, J.; Scherllin-Pirscher, B.; Steiner, A. K.

    2013-12-01

    Monitoring the atmosphere to gain accurate and long-term stable records of essential climate variables (ECVs) such as temperature and greenhouse gases is the backbone of contemporary atmospheric and climate science. Earth observation from space is the key to obtain such data globally in the atmosphere. Currently, however, not any existing satellite-based atmospheric ECV record can serve as authoritative benchmark over months to decades so that climate variability and change in the atmosphere are not yet reliably monitored. Radio occultation (RO) using Global Navigation Satellite System (GNSS) signals provides a unique opportunity to solve this problem in the free atmosphere (from ~1-2 km altitude upwards) for core ECVs: the thermodynamic variables temperature and pressure, and to some degree water vapor, which are key parameters for tracking climate change. On top of RO we have recently conceived next-generation methods, microwave and infrared-laser occultation and nadir-looking infrared-laser reflectometry. These can monitor a full set of thermo-dynamic ECVs (incl. wind) as well as the greenhouse gases such as carbon dioxide and methane as main drivers of climate change; for the latter we also target the boundary layer for tracking carbon sources and sinks. We briefly introduce to why the atmospheric climate monitoring challenge is unsolved so far and why just the above methods have the capabilities to break through. We then focus on RO, which already provided more than a decade of observations. RO accurately measures time delays from refraction of GNSS signals during atmospheric occultation events. This enables to tie RO-derived ECVs and their uncertainty to fundamental time standards, effectively the SI second, and to their unique long-term stability and narrow uncertainty. However, despite impressive advances since the pioneering RO mission GPS/Met in the mid-1990ties no rigorous trace from fundamental time to the ECVs (duly accounting also for relevant side

  3. A new solar forcing record for the past 9400 years and its imprint in climate

    NASA Astrophysics Data System (ADS)

    Steinhilber, F.; Beer, J.

    2011-12-01

    For studies of the solar-terrestrial relationship in the past (and future), solar activity has to be known. Solar activity can be reconstructed using cosmogenic radionuclides (10Be from polar ice cores and 14C from tree rings); these are produced in the Earth's atmosphere by cosmic ray particles, which are modulated by solar and geomagnetic activity. After production due to solar and geomagnetic activity the radionuclides are distributed in their respective geochemical systems before they get stored in natural archives (10Be in polar ice cores and 14C in trees). Changes in the geochemical systems add local (record-dependent) noise to the global radionuclide production signal. By applying principal component analysis to several 10Be records from ice cores from Greenland and Antarctica and the 14C record from tree rings, we were able to extract the global production signal and to remove the local noise signal. In the final step we used the physical relationship between radionuclide production and solar activity and obtained a new low-noise reconstruction of 22-year averaged solar forcing for the past 9400 years. Spectral analysis of solar forcing shows distinct periodicities, which are used to predict the average solar cycle activity for the next 200 years; the occurrence of a grand solar minimum around 2100 is likely, however an exact prediction of the amplitude is difficult. The record of solar forcing is used to identify the solar imprint in published climate records from different regions. In several periods good agreement is found between changes in solar activity and climate. However there are also periods without any agreement, which may be explained by other important forcing factors such as volcanoes and greenhouse gases and their corresponding feedback effects. The new solar forcing record may help to distinguish between the different forcing factors when used as an input parameter in climate models.

  4. In Search of Sun-Climate Connection Using Solar Irradiance Measurements and Climate Records

    NASA Technical Reports Server (NTRS)

    Kiang, Richard K.; Kyle, H. Lee

    2000-01-01

    The Earth's temperature has risen approximately 0.5 degree-C in the last 150 years. Because the atmospheric concentration of carbon dioxide has increased nearly 30% since the industrial revolution, a common conjecture, supported by various climate models, is that anthropogenic greenhouse gases have contributed to global warming. Another probable factor for the warming is the natural variation of solar irradiance. Although the variation is as small as 0.1 % it is hypothesized that it contributes to part of the temperature rise. Warmer or cooler ocean temperature at one part of the Globe may manifest as abnormally wet or dry weather patterns some months or years later at another part of the globe. Furthermore, the lower atmosphere can be affected through its coupling with the stratosphere, after the stratospheric ozone absorbs the ultraviolet portion of the solar irradiance. In this paper, we use wavelet transforms based on Morlet wavelet to analyze the time-frequency properties in several datasets, including the Radiation Budget measurements, the long-term total solar irradiance time series, the long-term temperature at two locations for the North and the South Hemisphere. The main solar cycle, approximately 11 years, are identified in the long-term total solar irradiance time series. The wavelet transform of the temperature datasets show annual cycle but not the solar cycle. Some correlation is seen between the length of the solar cycle extracted from the wavelet transform and the North Hemisphere temperature time series. The absence of the 11-year cycle in a time series does not necessarily imply that the geophysical parameter is not affected by the solar cycle; rather it simply reflects the complex nature of the Earth's response to climate forcings.

  5. Using image reconstruction methods to enhance gridded resolutionfor a newly calibrated passive microwave climate data record

    NASA Astrophysics Data System (ADS)

    Paget, A. C.; Brodzik, M. J.; Gotberg, J.; Hardman, M.; Long, D. G.

    2014-12-01

    Spanning over 35 years of Earth observations, satellite passive microwave sensors have generated a near-daily, multi-channel brightness temperature record of observations. Critical to describing and understanding Earth system hydrologic and cryospheric parameters, data products derived from the passive microwave record include precipitation, soil moisture, surface water, vegetation, snow water equivalent, sea ice concentration and sea ice motion. While swath data are valuable to oceanographers due to the temporal scales of ocean phenomena, gridded data are more valuable to researchers interested in derived parameters at fixed locations through time and are widely used in climate studies. We are applying recent developments in image reconstruction methods to produce a systematically reprocessed historical time series NASA MEaSUREs Earth System Data Record, at higher spatial resolutions than have previously been available, for the entire SMMR, SSM/I-SSMIS and AMSR-E record. We take advantage of recently released, recalibrated SSM/I-SSMIS swath format Fundamental Climate Data Records. Our presentation will compare and contrast the two candidate image reconstruction techniques we are evaluating: Backus-Gilbert (BG) interpolation and a radiometer version of Scatterometer Image Reconstruction (SIR). Both BG and SIR use regularization to trade off noise and resolution. We discuss our rationale for the respective algorithm parameters we have selected, compare results and computational costs, and include prototype SSM/I images at enhanced resolutions of up to 3 km. We include a sensitivity analysis for estimating sensor measurement response functions critical to both methods.

  6. Climate or land-use change? Complexities in the attribution of trends in river flow records

    NASA Astrophysics Data System (ADS)

    Harrigan, S.; Murphy, C.; Noone, S.; Wilby, R. L.; Hall, J.

    2012-12-01

    Uncertainty associated with projections of regional climate change and the challenge of developing adaptation responses are heightening interest in trend detection from observations. In many studies, attribution of detected trends in river flow has been based on the assessment of correlations with large scale modes of climate variability, with too little emphasis being placed on understanding non-climatic changes within the catchment. The River Boyne in Ireland has been cited as exhibiting a climate driven increase in river flows associated with a shift towards positive anomalies in the North Atlantic Oscillation Index (NAOI) from the mid to late 1970s. However, metadata suggests that the catchment was subjected to extensive arterial drainage during the period 1969-86. This was installed to improve land drainage and reduce the frequency/ extent of overland flooding, particularly through river straightening and channel deepening, complicating the attribution of change linked to climatic drivers. This study uses river flow records from the pre-drainage period along with meteorological data to calibrate conceptual rainfall runoff models in order to reconstruct continuous flow series spanning the pre- and post-drainage eras. Model parameter and structure uncertainties were explored via a suite of conceptually and structurally diverse models. Archival rainfall records dating from the late 1800s were used to further extend the flow series. Reconstructed flows are analyzed for both monotonic and step changes using a variety of statistical tests. Emphasis is placed on a moving windows approach to assess the evolution of trends throughout the reconstructed series. Our results show that the variability of trends (direction, magnitude and significance) is heavily dependent on the choice of record start and end dates. Rather than being associated with a change point in the NAOI, the mid 1970s step change is shown to coincide with the documented changes in arterial drainage

  7. Interaction between the ENSO and the Asian monsoon in a coral record of tropical climate

    SciTech Connect

    Charles, C.D.; Hunter, D.E.; Fairbanks, R.G.

    1997-08-15

    The oxygen isotopic composition of a banded coral from the western equatorial Indian Ocean provides a 150-year-long history of the relation between the El Nino-Southern Oscillation (ENSO) phenomenon and the Asian monsoon. Interannual cycles in the coral time series were found to correlate with Pacific coral and instrumental climate records, suggesting a consistent linkage across ocean basins, despite the changing frequency and amplitude of the ENSO. However, decadal variability that is characteristic of the monsoon system also dominates the coral record, which implies important interactions between tropical and midlatitude climate variability. One prominent manifestation of this interaction is the strong amplitude modulation of the quasi-biennial cycle. 26 refs., 4 figs.

  8. Annually resolved ice core records of tropical climate variability over the past ~1800 years.

    PubMed

    Thompson, L G; Mosley-Thompson, E; Davis, M E; Zagorodnov, V S; Howat, I M; Mikhalenko, V N; Lin, P-N

    2013-05-24

    Ice cores from low latitudes can provide a wealth of unique information about past climate in the tropics, but they are difficult to recover and few exist. Here, we report annually resolved ice core records from the Quelccaya ice cap (5670 meters above sea level) in Peru that extend back ~1800 years and provide a high-resolution record of climate variability there. Oxygen isotopic ratios (δ(18)O) are linked to sea surface temperatures in the tropical eastern Pacific, whereas concentrations of ammonium and nitrate document the dominant role played by the migration of the Intertropical Convergence Zone in the region of the tropical Andes. Quelccaya continues to retreat and thin. Radiocarbon dates on wetland plants exposed along its retreating margins indicate that it has not been smaller for at least six millennia. PMID:23558172

  9. Climate and ocean dynamics and the lead isotopic records in pacific ferromanganese crusts

    SciTech Connect

    Christensen, J.N.; Halliday, A.N.; Rea, D.K.

    1997-08-15

    As hydrogenous iron-manganese crusts grow, at rates of millimeters per million years, they record changes in the lead isotopic composition of ambient seawater. Time-resolved lead isotopic data for cut slabs of two central Pacific iron-manganese crusts that have been growing since about 50 million years ago were measured in situ by laser ablation, multiple-collector, inductively coupled plasma mass spectrometry. The lead isotopic compositions have remained remarkably uniform over the past 30 million years, but the record of small variations corresponds with other paleoceanographic indicators of climate change, including weathering and glaciation. This implies that despite the short residence time of lead in the oceans, global mechanisms may influence lead isotopic compositions in the central Pacific, far from continental inputs, because of changes in weathering, ocean circulation, and degree of mixing. Thus lead isotopic data could be used to probe climate-driven changes in ocean circulation through time. 40 refs., 4 figs.

  10. Sedimentation controls on the preservation and time resolution of climate-proxy records from shallow fluctuating lakes

    NASA Astrophysics Data System (ADS)

    Verschuren, Dirk

    1999-05-01

    Lithological stratigraphies of 210Pb-dated sediment cores from four hydrologically interconnected fluctuating lake basins in Kenya are used to investigate how differences in basin morphometry and physical limnology influence the preservation and time resolution of sedimentary climate-proxy records. The potential of lakes to accumulate an undisturbed sediment record is primarily determined by their relative depth, the ratio between maximum depth and effective wind fetch. Chemically stratified crater lakes accumulate high-quality climate-proxy records because they complement great relative depth with topographical wind shelter, resistance of density stratification to propagation of wind-induced turbulence, and absence of bioturbation in anoxic bottom waters. The changes in water-column circulation and bottom dynamics that accompany lake-level fluctuations affect the time resolution of accumulating climate-proxy signals and thus the apparent magnitude and frequency of inferred climatic events. An episode of low lake level can be both over- or underrepresented in the climate-proxy record depending on the severity of the drawdown relative to the lake's critical depth of sediment accumulation. Decade-scale hiatuses due to non-deposition or erosion at low lake level may be difficult to recognize because mixing of unconsolidated muds deposited before and after the lowstand can obliterate evidence that the record has been truncated. Regional correlation of climate-proxy records must consider both hydrology-related differences in the climatic sensitivity of lakes and sedimentation-related differences in the integrity of their climate-history archives.

  11. Investigating annually-resovled natural climate variability during MIS 11 using lacustrine records

    NASA Astrophysics Data System (ADS)

    Tye, G. J.; Palmer, A. P.; Candy, I.; Coxon, P.; Hardiman, M.

    2012-04-01

    Marine isotope stage 11 (MIS 11, ca 410,000 yrs BP) is considered to be one of the best analogues for current and future climate change due to the similarity of orbital forcing patterns during these two interglacials. Marine and ice-core records suggest that MIS 11 was a particularly long interglacial, characterised by stable climates. The investigation of high-resolution climate records from MIS 11 can, therefore, allow us to understand how the climate of a Holocene-like interglacial might evolve in the absence of anthropogenic modification. MIS 11 sediments preserved in the palaeolake basin at Marks Tey, eastern England, offer the potential for such a study as they are considered to be annually-laminated (varved) throughout a large part of the interglacial (Turner, 1970, 1975). The lamination sets appear to be comprised, primarily, of three regularly occurring laminae types; 1) authigenic carbonate, 2) diatom blooms, and 3) organic detritus, although there appears to be some variability in the microfacies of these laminations. The carbonate laminations are the key to the study of climate variability during MIS 11, as they represent authigenic carbonate precipitation, consistent with temperature/biologically driven changes in lake chemistry during the summer months. Oxygen isotopic analysis of the carbonate therefore gives a proxy for summer temperature. A period of key interest in the MIS 11 sequence at Marks Tey occurs during the early part of the interglacial, where there is a short-lived increase in grass pollen relative to tree pollen, termed the Non-Arboreal Pollen Zone (NAPZ). The cause of this shift in pollen has been subject to debate, with natural wildfire (Turner, 1970) or climatic deterioration (e.g. Kelly, 1964) being suggested as possible forcing mechanisms. In this study, as well as discussing the main characteristics of the MIS 11 sequence at Marks Tey, we will focus on the sedimentary, micromorphological and geochemical record of the NAPZ. In

  12. The origin of the 1500-year climate cycles in Holocene North-Atlantic records

    NASA Astrophysics Data System (ADS)

    Debret, M.; Bout-Roumazeilles, V.; Grousset, F.; Desmet, M.; McManus, J. F.; Massei, N.; Sebag, D.; Petit, J.-R.; Copard, Y.; Trentesaux, A.

    2007-10-01

    Since the first suggestion of 1500-year cycles in the advance and retreat of glaciers (Denton and Karlen, 1973), many studies have uncovered evidence of repeated climate oscillations of 2500, 1500, and 1000 years. During last glacial period, natural climate cycles of 1500 years appear to be persistent (Bond and Lotti, 1995) and remarkably regular (Mayewski et al., 1997; Rahmstorf, 2003), yet the origin of this pacing during the Holocene remains a mystery (Rahmstorf, 2003), making it one of the outstanding puzzles of climate variability. Solar variability is often considered likely to be responsible for such cyclicities, but the evidence for solar forcing is difficult to evaluate within available data series due to the shortcomings of conventional time-series analyses. However, the wavelets analysis method is appropriate when considering non-stationary variability. Here we show by the use of wavelets analysis that it is possible to distinguish solar forcing of 1000- and 2500- year oscillations from oceanic forcing of 1500-year cycles. Using this method, the relative contribution of solar-related and ocean-related climate influences can be distinguished throughout the 10 000 yr Holocene intervals since the last ice age. These results reveal that the 1500-year climate cycles are linked with the oceanic circulation and not with variations in solar output as previously argued (Bond et al., 2001). In this light, previously studied marine sediment (Bianchi and McCave, 1999; Chapman and Shackleton, 2000; Giraudeau et al., 2000), ice core (O'Brien et al., 1995; Vonmoos et al., 2006) and dust records (Jackson et al., 2005) can be seen to contain the evidence of combined forcing mechanisms, whose relative influences varied during the course of the Holocene. Circum-Atlantic climate records cannot be explained exclusively by solar forcing, but require changes in ocean circulation, as suggested previously (Broecker et al., 2001; McManus et al., 1999).

  13. The origin of the 1500-year climate cycles in Holocene North-Atlantic records

    NASA Astrophysics Data System (ADS)

    Debret, M.; Bout-Roumazeilles, V.; Grousset, F.; Desmet, M.; McManus, J. F.; Massei, N.; Sebag, D.; Petit, J.-R.; Copard, Y.; Trentesaux, A.

    2007-03-01

    Since the first suggestion of 1500-year cycles in the advance and retreat of glaciers (Denton and Karlen, 1973), many studies have uncovered evidence of repeated climate oscillations of 2500, 1500, and 1000 years. During last glacial period, natural climate cycles of 1500 years appear to be persistent (Bond and Lotti, 1995) and remarkably regular (Mayewski et al., 1997; Rahmstorf, 2003), yet the origin of this pacing during the Holocene remains a mystery (Rahmstorf, 2003), making it one of the outstanding puzzles of climate variability. Solar variability is often considered likely to be responsible for such cyclicities, but the evidence for solar forcing is difficult to evaluate within available data series due to the shortcomings of conventional time-series analyses. However, the wavelets analysis method is appropriate when considering non-stationary variability. Here we show by the use of wavelets analysis that it is possible to distinguish solar forcing of 1000- and 2500- year oscillations from oceanic forcing of 1500-year cycles. Using this method, the relative contribution of solar-related and ocean-related climate influences can be distinguished throughout the 10 000 Holocene intervals since the last ice age. These results reveal that the mysteriously regular 1,500-year climate cycles are linked with the oceanic circulation and not with variations in solar output as previously argued (Bond et al., 2001). In this light, previously studied marine sediment (Bianchi and McCave, 1999; Giraudeau et al., 2000), ice core (O'Brien et al., 1995) and dust records (Jackson et al., 2005) can be seen to contain the evidence of combined forcing mechanisms, whose relative influences varied during the course of the Holocene. Circum-Atlantic climate records cannot be explained by solar forcing, but require changes in ocean circulation, as suggested previously (Broecker et al., 2001; McManus et al., 1999).

  14. Continental climate response to orbital forcing from biogenic silica records in Lake Baikal

    USGS Publications Warehouse

    Colman, Steven M.; Peck, J.A.; Karabanov, E.B.; Carter, Susan J.; Bradbury, J.P.; King, J.W.; Williams, D.F.

    1995-01-01

    CHANGES in insolation caused by periodic changes in the Earth's orbital parameters provide the primary forcing for global ice ages1-6. But it is not clear to what extent the climates in continental interiors are controlled directly by regional variations in insolation and to what extent they are driven instead by the highly nonlinear response of the oceans and ice sheets. Here we investigate this question using the record of biogenic silica in Lake Baikal as a proxy for climate change in this high-latitude mid-continental region. We find a good correlation between this record and that of marine oxygen isotopes4. Over the past 250 kyr the Baikal record exhibits both a strongly nonlinear component (manifested in a 100-kyr periodicity) and weaker direct-insolation components (manifested in the 41-kyr (obliquity) and 23- and 19-kyr (precession) orbital cycles). These results show that even though extreme continental climates such as this are influenced directly by insolation variations, they are dominated by the nonlinear rhythm of the oceans and ice sheets.

  15. Climatic and Anthropogenic Influences on Lake-Sediment Records in Western Mongolia

    NASA Astrophysics Data System (ADS)

    Shinneman, A. L.; Edlund, M. B.; Umbanhower, C. E.; Almendinger, J. E.; Soninkhishig, N.

    2008-12-01

    The Valley of the Great Lakes in western Mongolia is a unique ecosystem comprising a wide variety of terrestrial and aquatic habitats. Little is known about the long-term climate history of the region or the relative impact of climate and land-use on ecosystem development. Recent drought and rising temperatures in Mongolia have made an improved understanding of the regional moisture balance a pressing concern. Records from across arid Central Asia have shown substantial temporal and spatial variability in past correlation between temperature and moisture availability. Many of the available paleoclimate records from Mongolia are limited in temporal resolution and offer little information on recent changes in the precipitation- to-evaporation balance in the region. We have developed a 2000 year diatom-inferred record of salinity from western Mongolia demonstrating a negative correlation between temperature and effective moisture (warm- dry and cool-wet conditions) over this time period, analogous to many records from the nearby Tibetan Plateau. The Tibetan plateau is notable for climate records free from strong anthropogenic influence, a similar scenario might be expected on the western Mongolian steppe with its low population density and nomadic livelihood. However, Mongolian grasslands have seen substantial human impacts in the recent several decades. Since the end of Soviet authority in 1991, traditional nomadic herders have seen large incentives to increase the number of livestock in their household, particularly numbers of cashmere goat. The increasing demand and transitional regulation of these resources may be increasing the nutrient load in Mongolia's aquatic systems and creating a deleterious situation for both wildlife and local herders. Correspondence analysis (CCA) demonstrates that both salinity and total phosphorus concentrations account for unique and significant fractions of the observed variability in diatom communities among the lakes, allowing for

  16. Hemispherical Snow Water Equivalent Records of Satellite-Based Data and CMIP5 Climate Model Simulations

    NASA Astrophysics Data System (ADS)

    Luojus, Kari; Pulliainen, Jouni; Takala, Matias; Lemmetyinen, Juha; Smolander, Tuomo; Ikonen, Jaakko; Cohen, Juval; Derksen, Chris

    2013-04-01

    The European Space Agency (ESA) GlobSnow project has produced a daily hemisphere-scale satellite-based snow water equivalent (SWE) data record spanning more than 30-years. The GlobSnow SWE record, based on methodology by Pulliainen [1] utilizes a data-assimilation based approach for the estimation of SWE which was shown to be superior to the approaches depending solely on satellite-based data [2]. The GlobSnow SWE data record is based on the time-series of measurements by two different space-borne passive radiometers (SMMR and SSM/I) measuring in the microwave region, spanning from 1980 to present day at a spatial resolution of approximately 25 km. We briefly present the on-going efforts taking place for further enhancement of the satellite-based SWE retrieval and the way this transfers to the reliability of the long-term SWE climate record. The development of SWE retrieval are focused on application of a new HUT multi-layer snow emission model and variational snow density scheme for SWE retrieval and efforts carried out to improve the homogeneity of the long-term record of weather station-based snow depth observations that are applied within the SWE retrieval scheme. In addition, the GlobSnow satellite-based dataset is inter-compared with climate model simulations from the CMIP5 archive. The objective of this work is to investigate the performance of the CMIP5 models in capturing the evolution of hemispheric scale snow conditions for the period of 1980 to 2010. The climate model simulations on snow cover extent, snow depth and snow water equivalent are evaluated against the GlobSnow SWE record. The goal is to assess the performance of the CMIP5 models to simulate snow conditions for the time-period that is covered by satellite-based observations. The results indicate a clear decreasing trend in total hemispherical snow mass for the period of 1980 to 2010 in the remote-sensing based data record. The inter-comparison of satellite-based record and climate model

  17. NOAA's Satellite Climate Data Records: The Research to Operations Process and Current State

    NASA Astrophysics Data System (ADS)

    Privette, J. L.; Bates, J. J.; Kearns, E. J.; NOAA's Climate Data Record Program

    2011-12-01

    In support of NOAA's mandate to provide climate products and services to the Nation, the National Climatic Data Center initiated the satellite Climate Data Record (CDR) Program. The Program develops and sustains climate information products derived from satellite data that NOAA has collected over the past 30+ years. These are the longest sets of continuous global measurements in existence. Data from other satellite programs, including those in NASA, the Department of Defense, and foreign space agencies, are also used. NOAA is now applying advanced analysis techniques to these historic data. This process is unraveling underlying climate trend and variability information and returning new value from the data. However, the transition of complex data processing chains, voluminous data products and documentation into an systematic, configuration controlled context involves many challenges. In this presentation, we focus on the Program's process for research-to-operations transition and the evolving systems designed to ensure transparency, security, economy and authoritative value. The Program has adopted a two-phase process defined by an Initial Operational Capability (IOC) and a Full Operational Capability (FOC). The principles and procedures for IOC are described, as well as the process for moving CDRs from IOC to FOC. Finally, we will describe the state of the CDRs in all phases the Program, with an emphasis on the seven community-developed CDRs transitioned to NOAA in 2011. Details on CDR access and distribution will be provided.

  18. On the development of probabilistic climate reconstructions based on fossil pollen records

    NASA Astrophysics Data System (ADS)

    Schoelzel, C.; Hense, A.

    2009-04-01

    Past climate reconstructions based on proxy data help to understand natural climate variability. It is essential that palaeoenvironmental transfer functions between climate and proxy variables take in to account the stochastical nature of the climate system. Especially pollen based reconstructions are a complex issue, since pollen counts do not show direct relation to climatological parameters, e.g. due to plant competition and/or land cultivation. The idea is to assess the background knowledge from classical, more empirically based methods in order to develop statistical transfer functions between vegetation and climate. Two popular concepts, the indicator taxa approach (or MCR) as well as the biomisation (BIOME/PFT), are translated into a statistical framework in order to reconstruct January and July temperatures as well as annual precipitation during the Holocene (10,000yrs BP). This involves the problem of multivariate random vectors with non-normally distributed marginals, which has been adressed by using copulas. The methods are applied to fossil pollen records of laminated sediments from the Eifel region in Germany. On the one hand, the reconstructions indicate that pollen based reconstructions show larger uncertainty ranges than expected by several classical approaches. On the other hand, the indicator taxa approach is robust to the lack of modern analogues, which is an advantage in highly anthropogenically influenced areas such as the Mediterranean or Central Europe.

  19. Towards understanding North Pacific climate variabilty with instrumental and ice core records

    NASA Astrophysics Data System (ADS)

    Kelsey, Eric P.

    Reconstructing climate variability prior to the instrumental era is critical to advance our understanding of the Earth's climate system. Although many paleoclimate records from the North Atlantic basin have been studied, relatively few paleoclimate records have been recovered in the North Pacific leaving a gap in our knowledge concerning North Pacific climate variability. The Eclipse and Mount Logan Prospector-Russell ice cores are favorably located in the St. Elias Mountains, Yukon, Canada to document North Pacific climate variability over the late Holocene. Detailed analysis reveals a consistent relationship of surface air temperature (SAT) anomalies associated with extreme Arctic Oscillation (AO) and Pacific-North America (PNA) index values, and a consistent relationship of North Pacific sea level pressure (SLP) anomalies associated with extreme Mt. Logan annual [Na+] and Eclipse cold season accumulation values. Spatial SAT anomaly patterns are most consistent for AO and PNA index values ≥1.5 and ≤-1.5 during the period 1872-2010. The highest and lowest ˜10% of Eclipse warm and cold season stable isotopes are associated with distinct atmospheric circulation patterns. The most-fractionated isotope values occur with a weaker Aleutian Low, and the least-fractionated isotope values occur with an amplification of the Aleutian Low and northwestern North American ridge. The assumption of stationarity between ice core records and sea-level pressure was tested for the Eclipse cold season accumulation and Mt. Logan annual sodium concentration records for 1872-2001. A stationary relationship was found for ≥95% of years when Mt. Logan sodium concentrations were ≤1.32 microg/L, with positive SLP anomalies in the eastern North Pacific. This high frequency supports the use of low sodium values at Mt. Logan for a reconstruction of SLP prior to 1872. Negative SLP anomalies in the North Pacific occurred for extreme high sodium concentration years and positive SLP

  20. Towards a Seamless Global Long-Term Earth Radiation Budget Climate Data Record

    NASA Astrophysics Data System (ADS)

    Loeb, N. G.; Priestley, K.; Minnis, P.; Smith, W. L., Jr.; Su, W.; Kratz, D. P.; Kato, S.; Doelling, D.

    2015-12-01

    Earth's climate is determined by the exchange of radiant energy between the Sun, Earth and space. The absorbed solar radiation (ASR) fuels the climate system, providing the energy required for atmospheric and oceanic motions, and energy released to space in the form of outgoing longwave radiation (OLR) nearly balances ASR, ensuring a relatively stable climate. Owing to human activities, there is currently less emitted thermal radiation than absorbed solar radiation, leading to an accumulation of energy into the Earth's system, which is driving global warming. Achieving an understanding of Earth's energy flows requires an accurate description of how radiant energy at the top-of-atmosphere (TOA), within the atmosphere, and at the surface is distributed spatially, and how this changes with time. A central objective of the Clouds and the Earth's Radiant Energy System (CERES) project is the production of a long-term global climate data record of Earth's radiation budget from the TOA down to the surface along with the associated atmospheric and surface properties that influence this budget. The CERES team relies on a number of data sources, including broadband radiometers that measure incoming and reflected solar radiation and OLR, high-resolution spectral imagers, meteorological, aerosol and ozone assimilation data, and snow/sea-ice maps based on microwave radiometer data. While TOA radiation budget is determined from accurate broadband radiometer measurements, the surface radiation budget is derived indirectly through radiative transfer model calculations initialized using imager-based cloud and aerosol retrievals and meteorological assimilation data. In order to accurately capture changes in Earth's radiation budget from interannual to decadal timescales, satellite instruments used to produce these data records must be radiometrically stable and the input data stream must be free of artificial discontinuities. Otherwise, distinguishing real climate system changes from

  1. A 700-year paleoecological record of boreal ecosystem responses to climatic variation from Alaska.

    PubMed

    Tinner, Willy; Bigler, Christian; Gedye, Sharon; Gregory-Eaves, Irene; Jones, Richard T; Kaltenrieder, Petra; Krähenbühl, Urs; Hu, Feng Sheng

    2008-03-01

    Recent observations and model simulations have highlighted the sensitivity of the forest-tundra ecotone to climatic forcing. In contrast, paleoecological studies have not provided evidence of tree-line fluctuations in response to Holocene climatic changes in Alaska, suggesting that the forest-tundra boundary in certain areas may be relatively stable at multicentennial to millennial time scales. We conducted a multiproxy study of sediment cores from an Alaskan lake near the altitudinal limits of key boreal-forest species. Paleoecological data were compared with independent climatic reconstructions to assess ecosystem responses of the forest tundra boundary to Little Ice Age (LIA) climatic fluctuations. Pollen, diatom, charcoal, macrofossil, and magnetic analyses provide the first continuous record of vegetation fire-climate interactions at decadal to centennial time scales during the past 700 years from southern Alaska. Boreal-forest diebacks characterized by declines of Picea mariana, P. glauca, and tree Betula occurred during the LIA (AD 1500-1800), whereas shrubs (Alnus viridis, Betula glandulosa/nana) and herbaceous taxa (Epilobium, Aconitum) expanded. Marked increases in charcoal abundance and changes in magnetic properties suggest increases in fire importance and soil erosion during the same period. In addition, the conspicuous reduction or disappearance of certain aquatic (e.g., Isoetes, Nuphar, Pediastrum) and wetland (Sphagnum) plants and major shifts in diatom assemblages suggest pronounced lake-level fluctuations and rapid ecosystem reorganization in response to LIA climatic deterioration. Our results imply that temperature shifts of 1-2 degrees C, when accompanied by major changes in moisture balance, can greatly alter high-altitudinal terrestrial, wetland, and aquatic ecosystems, including conversion between boreal-forest tree line and tundra. The climatic and ecosystem variations in our study area appear to be coherent with changes in solar irradiance

  2. Holocene climate variability from ice core records in the Ross Sea area (East Antarctica)

    NASA Astrophysics Data System (ADS)

    Braida, Martina; Stenni, Barbara; Masson-Delmotte, Valerie; Pol, Katy; Selmo, Enricomaria; Mezgec, Karin

    2014-05-01

    Past polar climate variability can be documented at high resolution thanks to ice core records, which have revealed significant Holocene variations in Antarctica. Paleotemperature reconstructions from Antarctic ice cores are mainly based on δ18O (δD) records, a proxy for local, precipitation-weighted atmospheric temperatures. Here, we present a new climate record spanning the past 12,000 years resulting from high resolution (10 cm) stable isotope analyses of the ice core drilled at Talos Dome (TD) in East Antarctica from 2003 to 2007 in the framework of the TALDICE (TALos Dome Ice CorE) project. Talos Dome (72°49'S, 159°11'E; 2315 m; -41°C) is an ice dome on the edge of the East Antarctic plateau, where moisture is mainly advected from the Indian and western Pacific sectors of the Southern Ocean. Pacific moisture arriving at TD has been transported above the Ross Sea, where extensive presence of sea ice also occurs during summer. High-resolution δ18O data have been measured using both IRMS and CRDS techniques on 10 cm samples, leading to a mean time resolution of two years. The long-term trend of the TALDICE δ18O profile shows characteristic features already observed in other ice cores from the East Antarctic plateau. Following the approach of Pol et al. (2011), high frequency climate variability has been investigated using a 3000-year running standard deviation on the de-trended record. The results are compared to the same analysis performed on the nearby Taylor Dome ice core δ18O data, which is the single East Antarctic ice core showing a strong Holocene decreasing trend. Despite these trend differences, both sites share common features regarding changes in variance. We also investigate changes in deuterium excess, a proxy reflecting changes in moisture source conditions. Both deuterium excess records show a two-step increasing trend in the first part of the Holocene. Taylor Dome deuterium excess however depicts an enhanced variability since about 7000

  3. The Towuti Drilling Project: A new, long Pleistocene record of Indo-Pacific Climate

    NASA Astrophysics Data System (ADS)

    Russell, James M.; Vogel, Hendrik; Bijaksana, Satria; Melles, Martin

    2016-04-01

    Lake Towuti is the largest tectonic lake in Indonesia, and the longest known terrestrial sediment archive in Southeast Asia. Lake Towuti's location in central Indonesia provides an important opportunity to reconstruct long-term changes in terrestrial climate in the Western Pacific warm pool, heart of the El Niño-Southern Oscillation. Lake Towuti has extremely high rates of floral and faunal endemism and is surrounded by one of the most diverse tropical forests on Earth making it a hotspot of Southeast Asian biodiversity. The ultramafic rocks and soils surrounding Lake Towuti provide high concentrations of metals to the lake and its sediments that feed a diverse, exotic microbial community. From May - July, 2015, the Towuti Drilling Project, consisting of more than 30 scientists from eight countries, recovered over 1,000 meters of new sediment core from 3 different drill sites in Lake Towuti, including cores through the entire sediment column to bedrock. These new sediment cores will allow us to investigate the history of rainfall and temperature in central Indonesia, long-term changes in the composition of the region's rainforests and diverse aquatic ecosystems, and the micro-organisms living in Towuti's exotic, metal-rich sediments. The Indo-Pacific region plays a pivotal role in the Earth's climate system, regulating critical atmospheric circulation systems and the global concentration of atmospheric water vapor- the Earth's most important greenhouse gas. Changes in seasonal insolation, greenhouse gas concentrations, ice volume, and local sea level are each hypothesized to exert a dominant control on Indo-Pacific hydroclimate variations through the Pleistocene. Existing records from the region are short and exhibit fundamental differences and complexity in orbital-scale climate patterns that limit our understanding of the regional climate responses to climate boundary conditions. Our sediment cores, which span much of the past 1 million years, allow new tests of

  4. Climate variability and human impact in South America during the last 2000 years: synthesis and perspectives from pollen records

    NASA Astrophysics Data System (ADS)

    Flantua, S. G. A.; Hooghiemstra, H.; Vuille, M.; Behling, H.; Carson, J. F.; Gosling, W. D.; Hoyos, I.; Ledru, M. P.; Montoya, E.; Mayle, F.; Maldonado, A.; Rull, V.; Tonello, M. S.; Whitney, B. S.; González-Arango, C.

    2016-02-01

    An improved understanding of present-day climate variability and change relies on high-quality data sets from the past 2 millennia. Global efforts to model regional climate modes are in the process of being validated against, and integrated with, records of past vegetation change. For South America, however, the full potential of vegetation records for evaluating and improving climate models has hitherto not been sufficiently acknowledged due to an absence of information on the spatial and temporal coverage of study sites. This paper therefore serves as a guide to high-quality pollen records that capture environmental variability during the last 2 millennia. We identify 60 vegetation (pollen) records from across South America which satisfy geochronological requirements set out for climate modelling, and we discuss their sensitivity to the spatial signature of climate modes throughout the continent. Diverse patterns of vegetation response to climate change are observed, with more similar patterns of change in the lowlands and varying intensity and direction of responses in the highlands. Pollen records display local-scale responses to climate modes; thus, it is necessary to understand how vegetation-climate interactions might diverge under variable settings. We provide a qualitative translation from pollen metrics to climate variables. Additionally, pollen is an excellent indicator of human impact through time. We discuss evidence for human land use in pollen records and provide an overview considered useful for archaeological hypothesis testing and important in distinguishing natural from anthropogenically driven vegetation change. We stress the need for the palynological community to be more familiar with climate variability patterns to correctly attribute the potential causes of observed vegetation dynamics. This manuscript forms part of the wider LOng-Term multi-proxy climate REconstructions and Dynamics in South America - 2k initiative that provides the ideal

  5. Early to Mid-Holocene climate variability from multi-millennial tree ring isotope records

    NASA Astrophysics Data System (ADS)

    Ziehmer, Malin Michelle; Nicolussi, Kurt; Schlüchter, Christian; Leuenberger, Markus

    2015-04-01

    The evolution of Holocene climate and its variability in the Alps has been principally investigated by analyzing low-frequency archives. The environment of the Alps is known to react sensitively to changes in environmental conditions such as variations of precipitation and temperature, which can be observed in the current retreat of glaciers as a result of global warming in the course of global climate change. The mentioned low- frequency records such as glacier and tree line fluctuations reveal an evolution of Holocene climate from a generally warm Early and Mid to a relatively cool Late Holocene, whereas the rare high resolution records often do not indicate such a general long-term trend. The causes and mechanisms behind are not fully understood yet. Recent finds of wood remains of long-lived trees in Alpine glacier forefields changed the concept of Holocene glacier variability and therefore, the present understanding of Holocene climate dynamics as they prove that glaciers in the Alps were usually relatively small and short in their extension during the Early and Mid-Holocene (Joerin et al., 2008; Nicolussi, Schlüchter, 2012). Those findings of wood remains further prove that the natural variability of postglacial climate is still not sufficiently known. However; such knowledge is essential for climate model input and the ability to disentangle natural from anthropogenic influences on the Earth's climate. The aim of our study is to establish highly resolved isotope records from calendar-dated wood remains covering the past 9000 years. Samples are collected in glacier forefields in the Alps, thereby covering a large SW- NE transect. Wood samples are separated into 5-year tree ring blocks from which cellulose is extracted and is crushed by ultrasonic homogenization (Boettger et al., 2007; Laumer et al., 2009). As the amount of samples (>7000 samples to cover the whole Holocene) is immense, the improved preparation procedure shortens the time for each single

  6. Combining intermediate complexity models and seasonal palaeo records: how to deal with model and climate variability?

    NASA Astrophysics Data System (ADS)

    de Boer, H. J.; Dekker, S. C.; Wassen, M. J.

    2009-04-01

    Earth System Models of Intermediate Complexity (EMICs) are popular tools for palaeo climate simulations. Recent studies applied these models in comparison to terrestrial proxy records and aimed to reconstruct changes in seasonal climate forced by altered ocean circulation patterns. To strengthen this powerful methodology, we argue that the magnitude of the simulated atmospheric changes should be considered in relation to the internal variability of both the climate system and the intermediate complexity model. To attribute a shift in modelled climate to reality, this ‘signal' should be detectable above the ‘noise' related to the internal variability of the climate system and the internal variability of the model. Both noise and climate signals vary over the globe and change with the seasons. We therefore argue that spatial explicit fields of noise should be considered in relation to the strengths of the simulated signals at a seasonal timescale. We approximated total noise on terrestrial temperature and precipitation from a 29 member simulation with the EMIC PUMA-2 and global temperature and precipitation datasets. To illustrate this approach, we calculate Signal-to-Noise-Ratios (SNRs) in terrestrial temperature and precipitation on simulations of an El Niño warm event, a phase change in Atlantic Meridional Oscillation (AMO) and a Heinrich cooling event. The results of the El Niño and AMO simulations indicate that the chance to accurately detect a climate signal increases with increasing SNRs. Considering the regions and seasons with highest SNRs, the simulated El Niño anomalies show good agreement with observations (r² = 0.8 and 0.6 for temperature and precipitation at SNRs > 4). The AMO signals rarely surpass the noise levels and remain mostly undetected. The simulation of a Heinrich event predicts highest SNRs for temperature (up to 10) over Arabia and Russia during Boreal winter and spring. Highest SNRs for precipitation (up to 12) are predicted over

  7. High resolution 900 yr volcanic and climatic record from the Vostok area, East Antarctica

    NASA Astrophysics Data System (ADS)

    Osipov, E. Yu.; Khodzher, T. V.; Golobokova, L. P.; Onischuk, N. A.; Lipenkov, V. Ya.; Ekaykin, A. A.; Osipova, O. P.

    2013-05-01

    Detailed volcanic record of the last 900 yr (1093-2010 AD) has been received using high resolution (2-3 samples per accumulation year) sulfate measurements in four snow/firn cores from the Vostok station area, East Antarctica. Totally, 33 volcanic events have been identified in the record, including well-known low latitude eruption signals found in many polar ice cores (e.g., Pinatubo 1991, Agung 1963, Krakatoa 1883, Tambora 1815, Huanaputina 1600, Kuwae 1452), however in comparison with other Antarctic sites the record has more events covering the last 900 yr. The strongest volcanic signals occurred during mid-13th, mid-15th and 18th centuries. The largest volcanic signal of Vostok (both in sulfate concentration and flux) is the 1452 AD Kuwae eruption. Average snow accumulation rate calculated for the period 1093-2010 AD is 21.3 ± 2.3 mm H2O. Accumulation record demonstrates a slight positive trend, however sharply increased accumulation rate during the periods from 1600 to 1815 AD (by 11% from long-term mean) and from 1963 to 2010 AD (by 15%) are typical features of the site. Na+ record shows strong decadal-scale variability probably connected with coupled changes in atmospheric transport patterns over Antarctica (meridional circulation change) and local glaciology. The obtained high resolution climatic records suggest a high sensitivity of the Vostok location to environmental changes in Southern Hemisphere.

  8. Multidecadal climate variability in Brazil's Nordeste during the last 3000 years based on speleothem isotope records

    NASA Astrophysics Data System (ADS)

    Novello, Valdir F.; Cruz, Francisco W.; Karmann, Ivo; Burns, Stephen J.; Stríkis, Nicolás M.; Vuille, Mathias; Cheng, Hai; Lawrence Edwards, R.; Santos, Roberto V.; Frigo, Everton; Barreto, Eline A. S.

    2012-12-01

    We present the first high resolution, approximately ∼4 years sample spacing, precipitation record from northeastern Brazil (hereafter referred to as ‘Nordeste’) covering the last ∼3000 yrs from 230Th-dated stalagmites oxygen isotope records. Our record shows abrupt fluctuations in rainfall tied to variations in the intensity of the South American summer monsoon (SASM), including the periods corresponding to the Little Ice Age (LIA), the Medieval Climate Anomaly (MCA) and an event around 2800 yr B.P. Unlike other monsoon records in southern tropical South America, dry conditions prevailed during the LIA in the Nordeste. Our record suggests that the region is currently undergoing drought conditions that are unprecedented over the past 3 millennia, rivaled only by the LIA period. Using spectral, wavelet and cross-wavelet analyses we show that changes in SASM activity in the region are mainly associated with variations of the Atlantic Multidecadal Oscillation (AMO) and to a lesser degree caused by fluctuations in tropical Pacific SST. Our record also shows a distinct periodicity around 210 years, which has been linked to solar variability.

  9. Using Coastal Ice Cap Records to Investigate Maritime Climate and Ice Sheet Processes in West Greenland

    NASA Astrophysics Data System (ADS)

    Das, S. B.; Evans, M. J.; Frey, K. E.; Osman, M. B.; Smith, B. E.; Stevens, L. A.; Trusel, L. D.; York, A.; Bingham, M.

    2014-12-01

    Recent changes, including outlet glacier retreat and speedup, and increased rates of surface melting, have dramatically increased the Greenland ice sheet contribution to sea-level rise over the past few decades. Increasingly studies point towards the influence of coupled ocean-ice processes in modulating Greenland ice sheet mass balance and glacier behavior in response to climate change, but many of these studies are limited to the past few years to decades, restricting our ability to understand these ocean-ice relationships over longer time periods. Ice core records have the potential to provide unique, high-resolution records of interest (e.g. accumulation and melt variability, as well as contemporaneous proxy records of regional air temperature and sea surface conditions), but suitable Greenland ice sheet coring regions are often located far inland (>200 km) from many maritime regions of interest. In this study we focus on new records from previously unstudied maritime ice caps (10-30 km from the coast) to reconstruct past environmental conditions in the Disko, Ummannaq and Baffin Bay regions. Here we present results from our recent 2014 field investigation of three high altitude ice caps (1300-2000 m) on Disko Island and the Nuussuaq Peninsula, as well as complementary results from two sites in the western ice sheet accumulation zone. Geophysical observations provide constraints on ice thickness, layering, and ice flow. Physical and chemical stratigraphic observations from snow pits and shallow firn cores are used to reconstruct recent accumulation rate and melt variability, as well as to develop and test environmental proxy relationships over the satellite era. Multi-century records from longer coastal ice cores, to be drilled in 2015, will contribute a key missing component to the existing observational record documenting ice, ocean and atmospheric changes in this region over a time period of dramatic change in Greenland ice sheet behavior (retreat and

  10. Coral δ18O records Porites vs. Diploastrea - sampling resolution and climatic signal!

    NASA Astrophysics Data System (ADS)

    Dassie, E. P.; Linsley, B. K.; Lambdin, S.

    2013-12-01

    Narrowing uncertainties in climate prediction is an economical and social need that could partially be addressed by the development of robust paleoclimatic networks. Porites is the most widely used genus in studies using massive corals from the Pacific Ocean, however only a few Pacific Porites records span more than 100 years. A different slower growing coral genius, Diploastrea, has the potential to also generate multi-century length paleo-records. Recent Paleoclimatic studies utilizing this genus have shown promising results (Watanabe et al., 2003; Bagnato et al., 2004, 2005). However, some sampling concerns still remain. Diploastrea has large individual corallites (4-5 times larger than Porites); these corallites include a straight inner portion (columella) surrounded by a radiating portion (septa). The septa portion does not grow perpendicular to the direction of the coral growth, but instead radiates at a 45° angle from the columella. Sampling both the columnar and septal portions simultaneously might produce erroneous climatic reconstructions, reflecting a combination of corallite material precipitated several months apart. Additionally, due to Diploastrea slower growing rate, a millimeter sampling resolution might not be enough to retrieve robust climatic information. This study determined the optimal sampling resolution for Diploastrea from Fiji and verified the fidelity of this archive to reconstruct climatic variability. δ18O and δ13C measurements were made on one Diploastrea and one Porites coral colonies from a lagoon in Kandavu, Fiji. Diploastrea (FKD2) was sampled and analyzed at a 0.25mm resolution and Porites (FKD1) at a one-mm resolution; taking into consideration the growth rate of these two cores, both sampling resolution corresponds to a nearly monthly resolution. We created low-resolution sampling from the high-resolution sampling of the Diploastrea and compared it to the Porites measurements. This leads to determine the optimal sampling

  11. Wetlands as a Record of Climate Change and Hydrological Response in Arid Rift Settings

    NASA Astrophysics Data System (ADS)

    Ashley, G. M.

    2004-12-01

    Of all the terrestrial depositional settings, rift basins typically provide the greatest accommodation space, and consequently have some of the longest records of continental sedimentation. Lake deposits were the only rift component studied for records of long-term climatic change and for testing hypotheses of orbital forcing. Recently, the continuing quest for the paleontological and cultural records of human origins entombed in the sedimentary rocks of the East African Rift System raised questions concerning hydrologic and biologic response to climatic change. Additional issues are the impact of climate on paleolandscapes and the environmental stresses that might have affected human evolution. Other important indicators of rift hydrology, such as springs and wetlands are now emerging as viable records of climate change. Rift valley basins are shallow, hydrologically closed systems that are responsive to shifts in climate, and specifically sensitive to changes in the hydrologic budget (P-ET). Long term wet-dry cycles in the low latitudes are thought to be astronomically controlled, i.e. Milankovitch precession cycles (19-23 ka). In the tropics, precipitation (P) varies with changes in solar insolation which fluctuates <8-10 % over a cycle. Stronger insolation drives stronger summer monsoon maxima increasing P. Mean annual temperatures are high, but evapo-transpiration, ET (~ 2500 mm/yr) varies little. Consequently, during wetter periods regional groundwater reservoirs enlarge, the water table rises and springs and wetlands increase in number and in size compared to drier periods. Lake levels are known to fluctuate in response to change in hydrologic budget and wetlands appear to respond similarly. Springs and groundwater-fed wetlands are common, however the sources and sustainability of water or what geologic factors lead to the formation and longevity of wetlands is not well established. It appears that rainfall is trapped on topographic highs (rift fault blocks

  12. Orbital forcing of continental climate during the Pleistocene: a complete astronomically-tuned climatic record from Lake Baikal, SE Siberia

    NASA Astrophysics Data System (ADS)

    Prokopenko, A. A.; Hinnov, L. A.; Williams, D. F.; Kuzmin, M. I.

    2007-12-01

    confirms SP-tuning efficacy. At the same time, however, an anomaly is observed between the BioSi obliquity component and the obliquity variation. A phasing of -32° ± 3° points to a possible inherent time-lagged response of BioSi (productivity) and terrestrial vegetation proxies to insolation forcing. The presence of this ca. 4-kyr lag suggests that factors other than 'slow physics of ice sheets' may have contributed to generating lagged responses to insolation in the northern hemisphere climate proxy records. Long-term changes in sedimentation rates in Lake Baikal at the hemipelagic drill site suggest a significant orbital forcing of sedimentation process (both biogenic and clastic) in this rift basin. The Middle Pleistocene Transition in the Lake Baikal record is associated with significant changes in average sedimentation rates, with a particularly high rate during glacial MIS 24 (880-900 ka) in contrast with rather low rates over MIS 23-19.We suggest the composite BDP-96 Baikal record as a new benchmark correlation target for terrestrial records in continental Eurasia as an alternative to June 65°N insolation and ODP marine oxygen isotope timescales, commonly used as targets for tuning loess/soil sections and palynological records in this part of the world.

  13. Climate change research in Massachusetts, U.S.A.: searching for phenology in the historical record.

    NASA Astrophysics Data System (ADS)

    Primack, R.; Miller-Rushing, A.

    2009-04-01

    The United States does not have as many large, well-researched sets of phenological records as can be found in Europe. Such phenological research is important both scientifically to investigate the effects of climate change and, just as importantly, for convincing the public that climate change is really happening and is already affecting our environment. Scientists in the United States are currently uncovering a wealth of data from a variety of unconventional sources on the effects of climate on the phenology of a wide range of organisms, with many studies being published on birds and plants. For the past six years, we have been investigating the impact of climate change in Massachusetts, a region with a particularly strong tradition of science and natural history. We are able to use combinations of herbarium specimens, photographs, diaries of individual naturalists, records from research stations, and current observations of our own to document the effects of climate change. Each of these data sources has certain limitations, but the overall message is the same: a warming climate is causing plants to flower earlier and certain migratory birds to arrive earlier. Such data has to be interpreted carefully due to issues of changing population sizes and changing sampling methods and intensity. The single most valuable source of data for our research has been the observations of flowering times of hundreds of plant species from 1852 to 1858 in Concord, Massachusetts, made by Henry David Thoreau. Thoreau is the most famous environmental philosopher in the United States, and most students read his book Walden. Later botanists also recorded flowering times and the abundance of plant species in Concord, and we recorded flowering times and species abundances in Concord starting in 2004. The project has shown that spring flowering species are the most responsive to temperatures, and that these plant species are now flowering seven days earlier than they were in the 1850s

  14. Numerical Modeling of Climatic Change from the Terminus Record of Lewis Glacier, Mount Kenya.

    NASA Astrophysics Data System (ADS)

    Kruss, Phillip Donald

    Over the last 100 years, the glaciers and lakes of East Africa have undergone dramatic change in response to climatic forcing. However, the available conventional meterological series have not proven sufficient to explain these environmental events. The secular climatic change at Lewis Glacier, Mount Kenya (0(DEGREES)9'S, 37(DEGREES)19'E), is reconstructed from its terminus record documented since 1893. The short-time-step numerical model developed for this study consists of climate and ice dynamics segments. The climate segment directly computes the effect on the net balance of change in the four forcings: precipitation, albedo, cloudiness, and temperature. The flow segment calculates the dynamic glacier response to net balance variation. Climatic change occurs over a wide range of time scales. Each glacier responds in a unique fashion to this spectrum of climatic forcings. The response of the Lewis terminus extent to repeated sinusoidal fluctuation in the net balance is calculated. The net balance versus elevation profile is separately translated along the orthogonal balance and elevation axes. Net balance amplitudes of 0.1 to 0.5 m a('-1) of ice and 10 to 50 m elevation, respectively, and periods ranging from 20 to 1000 years are covered. Consideration of the Lewis response is perspective with similar results for Hintereisferner, Storglaciaren, and Berendon and South Cascade Glaciers identifies general characteristics of the time lag and amplitude of the terminus response. The magnitude and timing of the change in only one of the climatic forcings precipitation, albedo, cloudiness, or temperature necessary to produce the retreat of the Lewis terminus from its late 19th century maximum are computed. Equivalent changes for two scenarios of simultaneous variation, namely precipitation/albedo/cloudiness and temperature/albedo, are also estimated. These numerical results are interpreted in the light of long-term lake level, river flow, and instrumental information. A

  15. 500-year climate cycles stacking of recent centennial warming documented in an East Asian pollen record

    PubMed Central

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

    2014-01-01

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

  16. Plant Functional Variability in Response to Late-Quaternary Climate Change Recorded in Ancient Packrat Middens

    NASA Astrophysics Data System (ADS)

    Holmgren, C. A.; Potts, D. L.

    2006-12-01

    Responses of plant functional traits to environmental variability are of enduring interest because they constrain organism performance and ecosystem function. However, most inferences regarding plant functional trait response to climatic variability have been limited to the modern period. To better understand plant functional response to long-term climate variability and how adjustments in leaf morphology may contribute to patterns of species establishment, persistence, or extirpation, we measured specific leaf area (SLA) from macrofossils preserved in ancient packrat middens collected along the Arizona/New Mexico border, USA. Our record spanned more than 32,000 years and included six woodland and Chihuahuan Desert species: Berberis cf. haematocarpa, Juniperus cf. coahuilensis, Juniperus osteosperma, Larrea tridentata, Prosopis glandulosa and Parthenium incanum. We predicted that regional climatic warming and drying since the late Pleistocene would result in intraspecific decreases in SLA. As predicted, SLA was positively correlated with midden age for three of the six species (L. tridentata, J. osteosperma, B. cf. haematocarpa). SLA was also negatively correlated with December (L. tridentata, J. cf. coahuilensis) or June (B. cf. haematocarpa, J. osteosperma) insolation. A unique record of vegetation community dynamics, plant macrofossils preserved in packrat middens also represent a rich and largely untapped source of information on long-term trends in species functional response to environmental change.

  17. 500-year climate cycles stacking of recent centennial warming documented in an East Asian pollen record.

    PubMed

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

    2014-01-01

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

  18. Antarctic climate variability from ice core records over the last two millennia

    NASA Astrophysics Data System (ADS)

    Braida, Martina; Stenni, Barbara; Masson-Delmotte, Valerie; Dreossi, Giuliano; Oerter, Hans; Selmo, Enricomaria; Severi, Mirko; Goosse, Hugues; Mezgec, Karin

    2013-04-01

    The climate of the past can be successfully investigated through the study of polar ice sheets. Paleotemperature reconstructions from Antarctic ice cores are based on water isotope profiles, thanks to the existing relationship between δ18O (or δD) and the temperature at the site. Here we present the climate record of the past 2000 years resulting from the stable isotope analysis of the ice core drilled at Talos Dome in East Antarctica from 2003 to 2007 in the framework of the European TALDICE (TALos Dome Ice CorE) project. Talos Dome (72°49'S, 159°11'E; 2315 m; -41°C) is an ice dome on the edge of the East Antarctic plateau. The snow accumulation rate of the site (80 kg m-2 yr-1) allows extracting high-resolution data for the past millennia. The main moisture sources of snow precipitation at this near-coastal site are located in the Indian Ocean and the Ross Sea. Isotopic analyses of TALDICE detailed (10 cm) samples have been performed in the framework of the ESF-HOLOCLIP project, whose main objective is to integrate the ice core, the marine core and the modeling data to investigate the climate variability of the high latitude southern hemisphere over the Holocene. The isotopic record obtained from the TALDICE ice core is here compared with a shallow firn core (89 m long) previously drilled at Talos Dome, at a 5 km distance, and covering the past 800 years. The two isotopic records are stacked to reduce the stratigraphic noise and compared with other available isotopic records from Antarctica to highlight common trends and regional variability in the climatic signal over the past two millennia. We compare the data with a simulation performed with a three-dimensional earth system model of intermediate complexity (LOVECLIM) with and without data assimilation. Considering the δ18O profile from the TALDICE ice core and comparing it with the ones from the other available records we can observe common negative isotopic anomalies in the period from about 1450 to

  19. Stable Isotopic Variations in Columnar Cacti: are Responses to Climate Recorded in Spines?

    NASA Astrophysics Data System (ADS)

    English, N. B.; Dettman, D. L.; Williams, D. G.

    2004-12-01

    The behavior of the North American monsoon (NAM), particularly with respect to times of continental drought and its relationship to the Pacific-North American (PNA) teleconnection pattern and the El Nino/Southern Oscillation (ENSO) is of great interest to paleoclimatologists and water managers. Long-term instrumental precipitation and tree ring records in the southwestern United States and northwestern Mexico at low elevations are sparse and this has hindered research on NAM variability at interannual timescales. Saguaro cacti (Carnegiea gigantea) and other columnar cacti in North and South America are long-lived and have the potential to record climate variability on land with high temporal and spatial resolution. The vertical sequence of spines on the saguaro's exterior represents a high resolution (4 to 6 per year), and long (over 150 years) record of environmental change. We present results from an experiment where we tracked the oxygen isotopic values in the source waters, stem tissue waters and spine tissue for three treatments over the course of three months. These data are then compared to a previously developed mechanistic model of isotopic variation that reflects the physiological responses of Saguaro to climate variation over seasonal to century long time-scales. We also present the rationale for a new method to determine the growth rate of columnar cacti using the radiocarbon bomb spike. Our measurements reveal that oxygen and hydrogen isotopic variation among the sequentially produced and persistent spines covering the saguaro body record fluctuations in saguaro water balance. The model successfully predicts isotopic variation in spines and constrains controlling variables, yielding a powerful and high-resolution stable isotope index of water stress in the low desert. The development and refinement of an isotopic model for saguaro will serve as the basis for models applied to other species of columnar cacti in North and South America. The role of the

  20. Floodplain ecohydrology: Discerning climatic v. anthropogenic controls from tree-ring δ18O, dendrochronology, and instrumental climate records

    NASA Astrophysics Data System (ADS)

    Singer, M. B.; Piégay, H.; Stella, J. C.; Wilson, R.

    2012-12-01

    Vegetation of lowland riparian zones in temperate climates is largely determined by floodplain water availability during the growth season. Floodplain water reservoirs are replenished seasonally by lateral hyporheic water from streamflow, which primarily contributes to phreatic zone water and by infiltration of precipitation, which typically controls seasonal vadose zone soil moisture. Water availability to species rooted to particular depths in the floodplain is subject to interannual variability in climate (e.g., precipitation magnitude, timing, and phase). Co-occurring tree species in the riparian zone may express differential adaptation to water availability and shifting water sources, especially if they are rooted at contrasting depths. We have developed an ecohydrologic approach to assess how climatic variability impacts water availability at different depths in the floodplain and corresponding tree growth in the Rhône River basin, France. We combine dendrochronology, tree ring isotopes (δ18O), and instrumental climate records to discern relationships between tree growth and water sources for two contrasting, co-occurring riparian species—the shallowly rooting Fraxinus excelsior and the obligate phreatophyte, Populus nigra (poplar). We developed growth time series via basal area increment (BAI) and extracted alpha-cellulose from tree rings to assess relative responses to water stress via δ18O contained in each annual ring, and we analyzed these data alongside streamflow, precipitation, and groundwater data. Our initial work on a tributary of the Rhône showed that F. excelsior generally indicates water availability in the vadose zone, while P. nigra provides a window into the phreatic zone. However, the rooting depths and water sources for these species overlap on particularly low topographic surfaces, where phreatic water is abundant for both. In contrast to prior assumptions, we found that P. nigra exhibits more growth sensitivity to drought stress

  1. Coralline alga reveals first marine record of subarctic North Pacific climate change

    USGS Publications Warehouse

    Halfar, J.; Steneck, R.; Schone, B.; Moore, G.W.K.; Joachimski, M.; Kronz, A.; Fietzke, J.; Estes, James

    2007-01-01

    While recent changes in subarctic North Pacific climate had dramatic effects on ecosystems and fishery yields, past climate dynamics and teleconnection patterns are poorly understood due to the absence of century-long high-resolution marine records. We present the first 117-year long annually resolved marine climate history from the western Bering Sea/Aleutian Island region using information contained in the calcitic skeleton of the long-lived crustose coralline red alga Clathromorphum nereostratum, a previously unused climate archive. The skeletal ??18O-time series indicates significant warming and/or freshening of surface waters after the middle of the 20th century. Furthermore, the time series is spatiotemporally correlated with Pacific Decadal Oscillation (PDO) and tropical El Nio??-Southern Oscillation (ENSO) indices. Even though the western Bering Sea/Aleutian Island region is believed to be outside the area of significant marine response to ENSO, we propose that an ENSO signal is transmitted via the Alaskan Stream from the Eastern North Pacific, a region of known ENSO teleconnections. Copyright 2007 by the American Geophysical Union.

  2. Challenges and Decisions in Producing a Sea Ice Concentration Climate Data Record

    NASA Astrophysics Data System (ADS)

    Savoie, M.; Meier, W.; Mallory, S. M.; Scott, D. J.

    2011-12-01

    Historic sea ice concentrations derived from satellite passive microwave sensors are an important climatological data set. Trends in extent are often cited as evidence of fundamental changes in the Earth's climate. The general public is increasingly aware of climate change, yet climate change deniers continue to spread misinformation by casting doubts when misrepresenting both data and scientific findings. To ensure data quality while increasing public confidence, increased transparency and full reproducibility should be a goal for every researcher. In NSIDC's recent effort to create a sea ice concentration Climate Data Record (CDR), our goal was to create a completely automated, reproducible data set that matched the existing widely-used, published data sets. In this presentation, we review the challenges we encountered and the solutions selected in the creation of the CDR. These included unreproducible ancillary files, manual editing of data, and uncertainty about the input data. As we strive to meet CDRs production requirements for reproducibility, we acknowledge we are sacrificing data quality without manual processes. Researchers must understand the provenance and quality of a data set when choosing to use it.

  3. New insights on Arctic Quaternary climate variability from palaeo-records and numerical modelling

    NASA Astrophysics Data System (ADS)

    Jakobsson, Martin; Long, Antony; Ingólfsson, Ólafur; Kjær, Kurt H.; Spielhagen, Robert F.

    2010-12-01

    Terrestrial and marine geological archives in the Arctic contain information on environmental change through Quaternary interglacial-glacial cycles. The Arctic Palaeoclimate and its Extremes (APEX) scientific network aims to better understand the magnitude and frequency of past Arctic climate variability, with focus on the "extreme" versus the "normal" conditions of the climate system. One important motivation for studying the amplitude of past natural environmental changes in the Arctic is to better understand the role of this region in a global perspective and provide base-line conditions against which to explore potential future changes in Arctic climate under scenarios of global warming. In this review we identify several areas that are distinct to the present programme and highlight some recent advances presented in this special issue concerning Arctic palaeo-records and natural variability, including spatial and temporal variability of the Greenland Ice Sheet, Arctic Ocean sediment stratigraphy, past ice shelves and marginal marine ice sheets, and the Cenozoic history of Arctic Ocean sea ice in general and Holocene oscillations in sea ice concentrations in particular. The combined sea ice data suggest that the seasonal Arctic sea ice cover was strongly reduced during most of the early Holocene and there appear to have been periods of ice free summers in the central Arctic Ocean. This has important consequences for our understanding of the recent trend of declining sea ice, and calls for further research on causal links between Arctic climate and sea ice.

  4. Solar and climate signal records in tree ring width from Chile (AD 1587 1994)

    NASA Astrophysics Data System (ADS)

    Rodolfo Rigozo, Nivaor; Roger Nordemann, Daniel Jean; Evangelista da Silva, Heitor; Pereira de Souza Echer, Mariza; Echer, Ezequiel

    2007-01-01

    Tree growth rings represent an important natural record of past climate variations and solar activity effects registered on them. We performed in this study a wavelet analysis of tree ring samples of Pilgerodendron cupressoides species, from Glaciar Pio XI (Lat: 49°12'S; 74°55'W; Alt: 25 m), Chile. We obtained an average chronology of about 400 years from these trees. The 11-yr solar cycle was present during the whole period in tree ring data, being more intense during Maunder minimum (1645-1715). The short-term periods, around 2-7 yr, that were found are more likely associated with ENSO effects. Further, we found significant periods around 52 and 80-100 yr. These periodicities are coincident with the fourth harmonic (52 yr) of the Suess cycle (208 yr) and Gleissberg (˜80-100 yr) solar cycles. Therefore, the present analysis shows evidence of solar activity effect/modulation on climatic conditions that affect tree ring growth. Although we cannot say with the present analysis if this effect is on local, regional or global climate, these results add evidence to an important role of solar activity over terrestrial climate over the past ˜400 yr.

  5. Simulated European stalagmite record and its relation to a quasi-decadal climate mode

    NASA Astrophysics Data System (ADS)

    Lohmann, G.; Wackerbarth, A.; Langebroek, P.; Werner, M.; Fohlmeister, J.; Scholz, D.; Mangini, A.

    2012-08-01

    A synthetic stalagmite record for the Bunker cave is constructed using a combined climate-stalagmite modeling approach. The power spectrum of the simulated speleothem calcite δ18O record has a pronounced peak at quasi-decadal time scale. Interestingly, mixing processes in the soil and karst above the cave represent a natural low-pass filter of the speleothem climate archive. We identify a quasi-decadal mode characterized by a "tripole pattern" of sea surface temperature affecting stalagmite δ18O values. This pattern, which is well-known in literature as the quasi-decadal mode in the North Atlantic, propagates eastwards and affects western European temperature surrounding the cave. Stalagmite δ18O values at Bunker Cave lag the regional surface temperature (r = 0.4) and soil moisture (r = -0.4) signal by 2-3 yr. Our modelling study suggests that stalagmite records from Bunker Cave are representative for large-scale teleconnections and can be used to obtain information about the North Atlantic and its decadal variability.

  6. Tree ring records capture long-term memory in climate systems

    NASA Astrophysics Data System (ADS)

    Schultz, Colin

    2013-03-01

    Measuring tree rings is a mainstay technique for estimating ancient climatic conditions, with a tree's year-by-year growth reflecting changes in precipitation and temperature. In some cases, paleoclimatological records compiled from tree ring measurements can stretch for thousands of years. Based on recent research, climatologists have found that hydrological and other systems have long-term memory. Drawing on tree ring measurements compiled from across the continental United States, Bowers et al. sought to determine whether such long-term relationships are preserved in ring width measurements. The authors analyzed the Hurst parameter—a measure of long-term memory—of 697 different tree ring records that were collected from 10 tree species from locations across the United States. They found that though each tree species had a different mean value for its Hurst parameter, meaning that each species recorded long-term trends in the climate differently, they all fell within the range suggestive of their being able to properly represent long-term memory.

  7. 1400 yr multiproxy record of climate variability from the northern Gulf of Mexico

    USGS Publications Warehouse

    Richey, J.N.; Poore, R.Z.; Flower, B.P.; Quinn, T.M.

    2007-01-01

    A continuous decadal-scale resolution record of climate variability over the past 1400 yr in the northern Gulf of Mexico was constructed from a box core recovered in the Pigmy Basin, northern Gulf of Mexico. Proxies include paired analyses of Mg/Ca and δ18O in the white variety of the planktic foraminifer Globigerinoides ruber and relative abundance variations of G. sacculifer in the foraminifer assemblages. Two multi-decadal intervals of sustained high Mg/Ca indicate that Gulf of Mexico sea surface temperatures (SSTs) were as warm or warmer than near-modern conditions between 1000 and 1400 yr B.P. Foraminiferal Mg/Ca during the coolest interval of the Little Ice Age (ca. 250 yr B.P.) indicate that SST was 2–2.5 °C below modern SST. Four minima in the Mg/Ca record between 900 and 250 yr B.P. correspond with the Maunder, Spörer, Wolf, and Oort sunspot minima, suggesting a link between changes in solar insolation and SST variability in the Gulf of Mexico. An abrupt shift recorded in both δ18Ocalcite and relative abundance of G. sacculifer occurred ca. 600 yr B.P. The shift in the Pigmy Basin record corresponds with a shift in the sea-salt-sodium (ssNa) record from the Greenland Ice Sheet Project 2 ice core, linking changes in high-latitude atmospheric circulation with the subtropical Atlantic Ocean.

  8. Hydrogen isotope ratios of palmitic acid in lacustrine sediments record late Quaternary climate variations

    NASA Astrophysics Data System (ADS)

    Huang, Yongsong; Shuman, Bryan; Wang, Yi; Webb, Thompson, III

    2002-12-01

    The rich paleoclimate information preserved in lacustrine sedimentary organic matter can be difficult to extract because of the mixed terrestrial and aquatic inputs. Herein we demonstrate that compound-specific hydrogen isotope analysis of palmitic acid, (PA), a ubiquitous compound in lacustrine sediments, captures the δD signals of lake water. Samples collected across a diverse range of 33 North American lakes show a strong correlation between water and δDPA values. At Crooked Pond, Massachusetts, the δDPA changes in a 14 k.y. sediment record parallel temperature trends inferred from fossil pollen. Downcore changes reveal differences between climatic trends in New England and in Greenland that are consistent with important regional differences in climate controls.

  9. A 2000 year varve-based climate record from the central Brooks Range, Alaska

    SciTech Connect

    Bird, BW; Abbott, MB; Finney, BP; Kutchko, B

    2009-01-01

    Varved minerogenic sediments from glacial-fed Blue Lake, northern Alaska, are used to investigate late Holocene climate variability. Varve-thickness measurements track summer temperature recorded at Atigun Pass, located 41 km east at a similar elevation (r (2) = 0.31, P = 0.08). Results indicate that climate in the Brooks Range from 10 to 730 AD (varve year) was warm with precipitation inferred to be higher than during the twentieth century. The varvetemperature relationship for this period was likely compromised and not used in our temperature reconstruction because the glacier was greatly reduced, or absent, exposing sub-glacial sediments to erosion from enhanced precipitation. Varve-inferred summer temperatures and precipitation decreased after 730 AD, averaging 0.4A degrees C above the last millennial average (LMA = 4.2A degrees C) from 730 to 850 AD, and 0.1A degrees C above the LMA from 850 to 980 AD. Cooling culminated between 980 and 1030 AD with temperatures 0.7A degrees C below the LMA. Varve-inferred summer temperatures increased between 1030 and 1620 AD to the LMA, though the period between 1260 and 1350 AD was 0.2A degrees C below the LMA. Although there is no equivalent to the European Medieval Warm Period in the Blue Lake record, two warm intervals occurred from 1350 to 1450 AD and 1500 to 1620 AD (0.4 and 0.3A degrees C above the LMA, respectively). During the Little Ice Age (LIA; 1620 to 1880 AD), inferred summer temperature averaged 0.2A degrees C below the LMA. After 1880 AD, inferred summer temperature increased to 0.8A degrees C above the LMA, glaciers retreated, but aridity persisted based on a number of regional paleoclimate records. Despite warming and glacial retreat, varve thicknesses have not achieved pre-730 AD levels. This reflects limited sediment availability and transport due to a less extensive retreat compared to the first millennium, and continued relative aridity. Overall, the Blue Lake record is similar to varve records from the

  10. Lake Sediment Records on Climate Change and Human Activities in the Xingyun Lake Catchment, SW China

    PubMed Central

    Zhang, Wenxiang; Ming, Qingzhong; Shi, Zhengtao; Chen, Guangjie; Niu, Jie; Lei, Guoliang; Chang, Fengqin; Zhang, Hucai

    2014-01-01

    Sediments from Xinyun Lake in central Yunnan, southwest China, provide a record of environmental history since the Holocene. With the application of multi-proxy indicators (total organic carbon (TOC), total nitrogen (TN), δ13C and δ15N isotopes, C/N ratio, grain size, magnetic susceptibility (MS) and CaCO3 content), as well as accelerator mass spectrometry (AMS) 14C datings, four major climatic stages during the Holocene have been identified in Xingyun′s catchment. A marked increase in lacustrine palaeoproductivity occurred from 11.06 to 9.98 cal. ka BP, which likely resulted from an enhanced Asian southwest monsoon and warm-humid climate. Between 9.98 and 5.93 cal. ka BP, a gradually increased lake level might have reached the optimum water depth, causing a marked decline in coverage by aquatic plants and lake productivity of the lake. This was caused by strong Asian southwest monsoon, and coincided with the global Holocene Optimum. During the period of 5.60–1.35 cal. ka BP, it resulted in a warm and dry climate at this stage, which is comparable to the aridification of India during the mid- and late Holocene. The intensifying human activity and land-use in the lake catchment since the early Tang Dynasty (∼1.35 cal. ka BP) were associated with the ancient Dian culture within Xingyun’s catchment. The extensive deforestation and development of agriculture in the lake catchment caused heavy soil loss. Our study clearly shows that long-term human activities and land-use change have strongly impacted the evolution of the lake environment and therefore modulated the sediment records of the regional climate in central Yunnan for more than one thousand years. PMID:25033404

  11. Geodetic mass balance record with rigorous uncertainty estimates deduced from aerial photographs and LiDAR data - case study from Drangajökull ice cap, NW-Iceland

    NASA Astrophysics Data System (ADS)

    Magnússon, E.; Belart, J. M. C.; Pálsson, F.; Ágústsson, H.; Crochet, P.

    2015-09-01

    In this paper we describe how recent high resolution Digital Elevation Models (DEMs) can be used as constraints for extracting glacier surface DEMs from old aerial photographs and to evaluate the uncertainty of the mass balance record derived from the DEMs. We present a case study for Drangajökull ice cap, NW-Iceland. This ice cap covered an area of 144 km2 when it was surveyed with airborne LiDAR in 2011. Aerial photographs spanning all or most of the ice cap are available from survey flights in 1946, 1960, 1975, 1985, 1994 and 2005. All ground control points used to constrain the orientation of the aerial photographs were obtained from the high resolution LiDAR DEM (2 m × 2 m cell size and vertical accuracy < 0.5 m). The LiDAR DEM was also used to estimate errors of the extracted photogrammetric DEMs in ice and snow free areas, at nunataks and outside the glacier margin. The derived errors of each DEM were used to constrain a spherical variogram model, which along with the derived errors in ice and snow free areas were used as inputs into 1000 Sequential Gaussian Simulations (SGSim). The simulations were used to estimate the possible bias in the entire glaciated part of the DEM. The derived bias correction, varying in magnitude between DEMs from 0.03 to 1.66 m (1946 DEM) was then applied. The simulation results were also used to calculate the 95 % confidence level of this bias, resulting in values between ±0.21 m (in 2005) and ±1.58 m (in 1946). Error estimation methods based on more simple proxies would typically yield 2-4 times larger error estimates. The aerial photographs used were acquired between late June and early October. An additional bias correction was therefore estimated using a degree day model to obtain the volume change between the start of two hydrological years (1 October). This correction corresponds to an average elevation change of ~ -3 m in the worst case for 1960, or about ~ 2/3 of volume change between the 1960 and the 1975 DEMs. The

  12. Maturity Matrices for Quality of Model- and Observation-Based Climate Data Records

    NASA Astrophysics Data System (ADS)

    Höck, Heinke; Kaiser-Weiss, Andrea; Kaspar, Frank; Stockhause, Martina; Toussaint, Frank; Lautenschlager, Michael

    2015-04-01

    In the field of Software Engineering the Capability Maturity Model is used to evaluate and improve software development processes. The application of a Maturity Matrix is a method to assess the degree of software maturity. This method was adapted to the maturity of Earth System data in scientific archives. The application of such an approach to Climate Data Records was first proposed in the context of satellite-based climate products and applied by NOAA and NASA. The European FP7 project CORE-CLIMAX suggested and tested extensions of the approach in order to allow the applicability to additional climate datasets, e.g. based on in-situ observations as well as model-based reanalysis. Within that project the concept was applied to products of satellite- and in-situ based datasets. Examples are national ground-based data from Germany as an example for typical products of a national meteorological service, the EUMETSAT Satellite Application Facility Network, the ESA Climate Change Initiative, European Reanalysis activities (ERA-CLIM) and international in situ-based climatologies such as GPCC, ECA&D, BSRN, HadSST. Climate models and their related output have some additional characteristics that need specific consideration in such an approach. Here we use examples from the World Data Centre for Climate (WDCC) to discuss the applicability. The WDCC focuses on climate data products, specifically those resulting from climate simulations. Based on these already existing Maturity Matrix models, WDCC developed a generic Quality Assessment System for Earth System data. A self-assessment is performed using a maturity matrix evaluating the data quality for five maturity levels with respect to the criteria data and metadata consistency, completeness, accessibility and accuracy. The classical goals of a quality assessment system in a data processing workflow are: (1) to encourage data creators to improve quality to reach the next quality level, (2) enable data consumers to decide

  13. Geochemical and Sedimentological Records of Late Quaternary Climate Change, Lake Tanganyika, Tropical East Africa

    NASA Astrophysics Data System (ADS)

    Felton, A. A.; Russell, J. M.; Cohen, A. S.; Baker, M. E.; McGlue, M. M.; Lezzar, K. E.

    2005-12-01

    We have analyzed piston core records from Lake Tanganyika (western Tanzania, East African Rift Valley) to investigate possible signals of tropical paleoclimate change during the Late Quaternary. Long paleoclimate records from East Africa are of importance for understanding climatic processes such as the role of solar variability in regulating tropical climates at Milankovitch time scales, and the relationship between abrupt climate changes, migration of Intertropical Convergence Zone, and regional climate variability (Nicholson, 2000). However, records of pre-Holocene climate variability from tropical African lakes (>25ka) are still quite rare. Long records from Lake Tanganyika are of particular interest given the lake's antiquity and its demonstrated potential for producing high resolution (frequently annually laminated) sedimentary records (Cohen et al., 1993). We analyzed physical properties, grain size, total organic carbon, major, minor and trace element variability, and biogenic silica data for a 7.75 m core from the Kalya slope and horst region of central Lake Tanganyika at 640m water depth. Nine 14C dates provide an age model for the core, which spans ~62 cal kyr. Elemental concentrations preserved in Lake Tanganyika sediments record variability in deposition and runoff into the lake basin. Under conditions of rapid erosion, exposure and rapid weathering of bedrock has been shown to generate high concentrations of original silicate minerals enriched in soluble cations such as sodium and potassium, elements that are also biologically conservative. Prior to 40ka cal yr. core sediments are characterized by high magnetic susceptibility, intermediate levels of organic carbon, low to intermediate levels of biogenic silica, and fine grain size, indicative of relatively high precipitation. There is a profound decrease in magnetic susceptibility, a decrease in organic carbon and an increase in grain size at 40ka cal yr, which persists until ~16ka cal yr. Seismic

  14. Recording of climate and diagenesis through fossil pigments and sedimentary DNA at Laguna Potrok Aike, Argentina

    NASA Astrophysics Data System (ADS)

    Vuillemin, A.; Ariztegui, D.; Leavitt, P. R.; Bunting, L.; Pasado Science Team

    2015-11-01

    Aquatic sediments record past climatic conditions while providing a wide range of ecological niches for microorganisms. Although marine sedimentary microbial assemblages are often defined by their surrounding geochemical conditions, the influence of environmental features upon microbial development and post-depositional survival remains largely unknown in the lacustrine realm. Due to long-term microbial activity, the composition of environmental DNA can be expected to evolve with sediment depth and over time and therefore should reflect both ancient and extant microbial populations, but this hypothesis has rarely been tested using a multiproxy approach. Here geomicrobiological and phylogenetic analyses of a Patagonian maar lake were used to indicate that the different sedimentary microbial assemblages derive from specific lacustrine regimes during defined climatic periods. Two well defined climatic intervals whose sediments harboured active microbial populations and measurable ATP were sampled for a comparative environmental study based on fossil pigments and 16S rRNA gene sequences. Bacterial and archaeal 16S rRNA gene sequences recovered from the Holocene record revealed a microbial community adapted to subsaline conditions actively producing methane during organic matter degradation. These characteristics were associated with sediments resulting from endorheic lake conditions with high evaporative stress and concomitant high algal productivity. Moreover, archaeal clone libraries established throughout the Holocene record indicate an age-related stratification of these populations, consistent with a gradual use of organic substrates after deposition. In contrast, sulphate-reducing bacteria and lithotrophic Archaea were predominant in sediments dated from the Last Glacial Maximum, in which pelagic clays alternated with fine volcanic material characteristic of a lake level highstand and freshwater conditions, but reduced water column productivity. These patterns

  15. A Lake Sediment Record of Climate Change and Human-Environment Interactions in Southwestern China

    NASA Astrophysics Data System (ADS)

    Hillman, A.; Abbott, M.; Yu, J.; Steinman, B. A.

    2012-12-01

    The delivery of precipitation to southwestern China is largely through monsoon circulation which has evolved with changing insolation during the Holocene. Additionally, southwestern China has a long history of human activity including mining, metallurgy, agriculture, and pollution. Here, high-resolution sampling of a sediment core from Lake Xing Yun in the Yunnan Province (24°10'N, 102°46'E), a drought sensitive lake that behaves as a closed basin system, provides a sub-decadal record of changing climate and human activity in the late Holocene. We use δ18O and δ13C measurements of authigenic carbonate precipitated from the lake water, magnetic susceptibility values, and hydrologic mass balance models to document the timing, direction, and magnitude of moisture changes associated with variations in monsoon strength. We also use δ13C and δ15N measurements on organic matter, carbon to nitrogen ratios, and sediment trace metal concentrations to assess the impact of human activity on the Xing Yun watershed. The 2,500 year record highlights several transition periods related to both human and climate forcing. The rise of intensive irrigation of the lake associated with agriculture occurs at 900 AD, coincident with the rise of metallurgy and mining activities. The period from 1200 to 1360 AD is marked by an abrupt decrease in δ18O values indicating that lake-level rose at this time. We attribute this to a shifting demographic change associated with political upheaval, which is supported by the leveling off of trace metal concentrations and the stagnation of metallurgy and mining activities. The most pronounced feature of the record is a rapid transition to substantially lower lake levels that persisted from 1360-1850 AD. This can be attributed to the return of dramatic human modification to the watershed and changing monsoon strength associated with the Little Ice Age. Using hydrologic mass balance models we are able to quantify the change that can be ascribed to

  16. Uncertainty Propagation in a Fundamental Climate Data Record derived from Meteosat Visible Band Data

    NASA Astrophysics Data System (ADS)

    Rüthrich, Frank; John, Viju; Roebeling, Rob; Wagner, Sebastien; Viticchie, Bartolomeo; Hewison, Tim; Govaerts, Yves; Quast, Ralf; Giering, Ralf; Schulz, Jörg

    2016-04-01

    The series of Meteosat First Generation (MFG) Satellites provides a unique opportunity for the monitoring of climate variability and of possible changes. 6 Satellites were operationally employed; all equipped with identical MVIRI radiometers. The time series now covers, for some parts of the globe, more than 34 years with a high temporal (30 minutes) and spatial (2.5 x 2.5 km²) resolution for the visible band. However, subtle differences between the radiometers in terms of the silicon photodiodes, sensor spectral ageing and variability due to other sources of uncertainties have limited the thorough exploitation of this unique time series so far. For instance upper level wind fields and surface albedo data records could be derived and used for the assimilation into Numerical Weather Prediction models for re-analysis and climate studies, respectively. However, the derivation of aerosol depth with high quality has not been possible so far. In order to enhance the quality of MVIRI reflectances for enabling an aerosol and improved surface albedo data record it is necessary to perform a re-calibration of the MVIRI instruments visible bands that corrects for above mentioned effects and results in an improved Fundamental Climate Data Record (FCDR) of Meteosat/MVIRI radiance data. This re-calibration has to be consistent over the entire period, to consider the ageing of the sensor's spectral response functions and to add accurate information about the combined uncertainty of the radiances. Therefore the uncertainties from all different sources have to be thoroughly investigated and propagated into the final product. This presentation aims to introduce all sources of uncertainty present in MVIRI visible data and points on the major mechanisms of uncertainty propagation. An outlook will be given on the enhancements of the calibration procedure as it will be carried out at EUMETSAT in the course of the EU Horizon 2020 FIDUCEO project (FIDelity and Uncertainty in Climate data

  17. A 3-Myr Mineral Magnetic Record of Saharan Dust Input Into the Eastern Mediterranean: Linking Magnetic Data With Climate Variability Over Northern Africa

    NASA Astrophysics Data System (ADS)

    Larrasoana, J.; Roberts, A. P.; Rohling, E. J.; Winklhofer, M.; Wehausen, R.

    2003-12-01

    We have produced a high resolution, 3-million-year mineral magnetic record for eastern Mediterranean sediments from Ocean Drilling Program Site 967. Rock magnetic analyses indicate that hematite dominates the high coercivity fraction of the sediments. We have developed a proxy (IRM0.9T@AF120mT) for the concentration of hematite by AF demagnetizing the IRM0.9T at 120 mT. A comparison of this proxy with Ti/Al data and other geochemical data indicates that variations in the concentration of hematite are related to the input of aeolian Saharan dust, regardless of non-steady-state diagenetic processes associated with organic-rich (sapropel) layers. We deduce that the eolian hematite in eastern Mediterranean sediments derives from the northern Sahara and relate dust production in this area with penetration of the African summer monsoon front to the north of the central Saharan watershed. Long-term variations in the penetration of the monsoon front would have led to changes in soil humidity and vegetation cover, and hence in the amount of dust production. Spectral analyses of our dust record reveal strong power at the precession, obliquity and eccentricity bands, which indicates that the northward penetration of the African monsoon, and thus northern African climate, is driven by a combination of low and high latitude mechanisms. We also observe a marked increase in dust supply and sub-Milankovitch variability around the mid-Pleistocene transition (~0.95 Ma), which suggests a link between millennial-scale climate variability, including monsoon dynamics, and the size of northern hemisphere ice sheets.

  18. Late Holocene interdecadal climate variability in the Sahel: inferences from a marine dust record offshore Senegal

    NASA Astrophysics Data System (ADS)

    Meyer, I.; Stuut, J.-B.; Mollenhauer, G.; Mulitza, S.; Zabel, M.

    2009-04-01

    Present-day climate in northwestern Africa strongly depends on the avaiability of water. At least since the Pliocene the Saharan Desert and the semiarid Sahel belt (tropical North Afrika) have been frequently affected by sudden shifts to more arid climate. The rate of change from arid to humid conditions is presently under heavy debate (e.g., deMenocal et al., 2001, Kröpelin et al., 2008). A recent example of abrupt droughts occurred in the early 70's and 80's of the last century. In this study we compare different high-resolution marine sediment records of Sahel climate variability from the Senegal mud belt, northwest Africa. Marine sediment cores show the variations of terrigenous input (both aeolian dust and fluvial matter) from the African continent. Due to their different distinctive grain-size distributions, aeolian dust and fluvial mud can be recognised and quantified in marine sediments (e.g., Stuut et al., 2002). Based on these variations in the grain-size distributions of the terrigenous sediment fraction, deconvolved with an end-member modelling algorithm (Weltje, 1997), are used to reconstruct rainfall variability and dust production on land for the last 4,000 years. References P. B. deMenocal, et al. (2001). Late Holocene Cultural Responses to Climate Change During the Holocene. Science 292, 667 S. Kröpelin, et al. (2008) Response to Comment on "Climate-Driven Ecosystem Succession in the Sahara: The Past 6000 Years" Science 322, 1326c G. J. Weltje (1997) End-member modeling of compositional data: Numerical-statistical algorithms for solving the explicit mixing problem. Mathematical Geology 9, 4

  19. Past climate changes and ecophysiological responses recorded in the isotope ratios of saguaro cactus spines.

    PubMed

    English, Nathan B; Dettman, David L; Sandquist, Darren R; Williams, David G

    2007-11-01

    The stable isotope composition of spines produced serially from the apex of columnar cacti has the potential to be used as a record of changes in climate and physiology. To investigate this potential, we measured the delta(18)O, delta(13)C and F(14)C values of spines from a long-lived columnar cactus, saguaro (Carnegiea gigantea). To determine plant age, we collected spines at 11 different heights along one rib from the stem apex (3.77 m height) to the base of a naturally occurring saguaro. Fractions of modern carbon (F(14)C) ranged from 0.9679 to 1.5537, which is consistent with ages between 1950 and 2004. We observed a very strong positive correlation (r = 0.997) between the F(14)C age of spines and the age of spines determined from direct and repeated height measurements taken on this individual over the past 37 years. A series of 96 spines collected from this individual had delta(18)O values ranging from 38 per thousand to 50 per thousand [Vienna standard mean ocean water (VSMOW)] and delta(13)C values from -11.5 per thousand to -8.5 per thousand [Vienna Peedee belemnite (VPDB)]. The delta(18)O and delta(13)C values of spines were positively correlated (r = 0.45, P < 0.0001) and showed near-annual oscillations over the approximately 15-year record. This pattern suggests that seasonal periods of reduced evaporative demand or greater precipitation input may correspond to increased daytime CO(2) uptake. The lowest delta(18)O and delta(13)C values of spines observed occurred during the 1983 and 1993 El Niño years, suggesting that the stable isotope composition recorded in spine tissue may serve as a proxy for these climate events. We compared empirical models and data from potted experimental cacti to validate these observations and test our hypotheses. The isotopic records presented here are the first ever reported from a chronosequence of cactus spines and demonstrate that tissues of columnar cacti, and potentially other long-lived succulents, may contain a

  20. Shoreline and Lacustrine Records of Late Quaternary Climate Change in the Chihuahuan Desert, Mexico

    NASA Astrophysics Data System (ADS)

    Castiglia, P. J.; Fawcett, P. J.

    2001-12-01

    Spatial and temporal patterns of Quaternary moisture and temperature variability in northern Mexico are difficult to reconstruct given the paucity of continuous, long-term Quaternary climate records from the region. Preliminary shoreline age dates and a pair of lacustrine sediment cores from Laguna Fresnal in northern Chihuahua, Mexico, record climate-driven variations in both lake level and sedimentologic input. Reeves (1969) first described Laguna Fresnal as part of Pluvial Lake Palomas, a Pleistocene lake composed of 3 interconnected sub-basins: Laguna Guzman, Santa Maria, and Fresnal. Six AMS 14C age dates from previously unrecognized lake fauna on a beach ridge complex indicate a number of Holocene lakes as well. These preserved shorelines increase in age with distance and elevation from the playa surface and include early Holocene (8456\\pm97 14C yrs BP; 1225 m asl), middle Holocene (6180\\pm53, 6401\\pm58, and 6721\\pm68 14C yrs BP; 1200 m asl), and Little Ice Age (435\\pm39 14C yrs BP; 1175 m asl) lake stands. These ages correlate with beach ridge chronologies throughout the western US and northern Mexico. However, during the middle Holocene Laguna Fresnal exhibits a pronounced high stand while other records show a prolonged dry episode. Two 17 m-long cores from the basin center provide a continuous record of sedimentation during the late Quaternary. Several abrupt changes in lake level are indicated by mud cracks preserved as sharp, light gray lineations (487-548 cm and 975-1130 cm), sharply overlain by finely laminated silt and clay. Drying episodes are preserved in the basal section of the cores as several 0.5-2 cm-thick gypsum horizons, overlain by 3-5 cm-thick, carbon-poor (0.02-0.05% TOC), light gray silt. Five distinct zones of coupled, alternating relatively high and low average magnetic susceptibility (MS) and bulk density further reveals changes in lacustrine sedimentation. Peaks in MS generally correlate with peaks in bulk density, with the

  1. Climate Variability Recorded in Earth System History: Contributions to our Understanding of a Changing Planet

    NASA Astrophysics Data System (ADS)

    Barron, E. J.

    2001-12-01

    The study of Earth System History is characterized by substantial innovation and excitement directed toward addressing the critical issue of understanding a changing planet and promoting new insights into the evolution of the Earth and its resources. Much of this innovation reflects the considerable expansion in the availability and quality of observations, particularly from the oceans, and the development and application of numerical models of the ocean-atmosphere-land-ice system. The key challenge within the Earth sciences is to develop a robust understanding of this coupled earth system and then to develop a predictive capability for natural variability and global change. Our capabilities are limited, among other things, by the fact that the instrumented record is too short to provide a strong sense of the character of change and the sensitivity of the Earth system. For this reason, modern observations are inadequate to demonstrate the capability of climate models to simulate conditions very different from the present day. The importance of Earth system history, and the ocean record in particular, stems from unique capabilities to: (1) assess the temporal and spatial characteristics of system variability, (2) define the nature of Earth sensitivity to a large number of forcing factors, including changes in ocean circulation and in greenhouse gases, (3) examine the integrated climatic, chemical and biologic response of the Earth system to a variety of spatial and temporal perturbations, (4) validate the predictions of numerical models for conditions very different from the present day, and (5) assess the rates of change associated with the evolution of the Earth and its components. Earth system history provides a great diversity of examples yielding a remarkable opportunity to develop insights into a broad range of issues and problems associated with the evolution of our planet. Three examples provide a focus for discussion. First, a careful analysis of climate

  2. Oxygen isotope records of Holocene climate variability in the Pacific Northwest

    NASA Astrophysics Data System (ADS)

    Steinman, Byron A.; Pompeani, David P.; Abbott, Mark B.; Ortiz, Joseph D.; Stansell, Nathan D.; Finkenbinder, Matthew S.; Mihindukulasooriya, Lorita N.; Hillman, Aubrey L.

    2016-06-01

    Oxygen isotope (δ18O) measurements of authigenic carbonate from Cleland Lake (southeastern British Columbia), Paradise Lake (central British Columbia), and Lime Lake (eastern Washington) provide a ∼9000 year Holocene record of precipitation-evaporation balance variations in the Pacific Northwest. Both Cleland Lake and Paradise Lake are small, surficially closed-basin systems with no active inflows or outflows. Lime Lake is surficially open with a seasonally active overflow. Water isotope values from Cleland and Paradise plot along the local evaporation line, indicating that precipitation-evaporation balance is a strong influence on lake hydrology. In contrast, Lime Lake water isotope values plot on the local meteoric water line, signifying minimal influence by evaporation. To infer past hydrologic balance variations at a high temporal resolution, we sampled the Cleland, Paradise, and Lime Lake sediment cores at 1-60 mm intervals (∼3-33 years per sample on average) and measured the isotopic composition of fine-grained (<63 μm) authigenic CaCO3 in each sample. Negative δ18O values, which indicate wetter conditions in closed-basin lakes, occur in Cleland Lake sediment from 7600 to 2200 years before present (yr BP), and are followed by more positive δ18O values, which suggest drier conditions, after 2200 yr BP. Highly negative δ18O values in the Cleland Lake record centered on ∼2400 yr BP suggest that lake levels were high (and that the lake may have been overflowing) at this time as a result of a substantially wetter climate. Similarly, Paradise Lake sediment δ18O values are relatively low from 7600 to 4000 yr BP and increase from ∼4000 to 3000 yr BP and from ∼2000 yr BP to present, indicating that climate became drier from the middle through the late Holocene. The δ18O record from Lime Lake, which principally reflects changes in the isotopic composition of precipitation, exhibits less variability than the closed-basin lake records and follows a

  3. Holocene record of glacier variability from lake sediments reveals tripartite climate history for Svalbard

    NASA Astrophysics Data System (ADS)

    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

  4. Marine record of Holocene climate, ocean, and cryosphere interactions: Herbert Sound, James Ross Island, Antarctica

    NASA Astrophysics Data System (ADS)

    Minzoni, Rebecca Totten; Anderson, John B.; Fernandez, Rodrigo; Wellner, Julia Smith

    2015-12-01

    The sediment record offshore James Ross Island, northeast Antarctic Peninsula presents an unparalleled opportunity to directly compare marine and terrestrial climate records spanning the Holocene in maritime Antarctica. An 11 m drill core was collected between Herbert Sound and Croft Bay as part of the SHALDRIL NBP-0502 initiative and produced the southernmost sediment record from the eastern side of the AP. Thirty-eight radiocarbon ages are used to construct an age model of centennial-scale resolution. Multi-proxy records, including magnetic susceptibility, pebble content, particle size, total organic carbon, and diatom assemblages, were interrogated in the context of nearby Holocene-age ice core, lake, and drift records from James Ross Island. Differences in the timing and expression of Holocene events reflect marine controls on tidewater glaciers, such as water mass configurations and sea ice. Glacial behavior mimics ice core paleotemperatures during the Holocene, with the exception of distinct ocean warming events. Herbert Sound was fully occupied by grounded ice during the Last Glacial Maximum, and experienced rapid lift-off, followed by a floating ice phase. The canopy of floating ice receded by 10 ± 2.4 cal kyr BP, presumably in response to Early Holocene warming. Herbert Sound and Croft Bay fully deglaciated by 7.2 cal kyr BP, when the Mid Holocene Hypsithermal commenced and the sound became open and productive. An extreme peak in productivity ˜6.1 cal kyr BP indicates an oceanic warming event that is not reflected in atmospheric temperature or lacustrine sediment records. Increase in sea ice cover and ice rafting mark the onset of the Neoglacial ˜2.5 cal kyr BP, when pronounced atmospheric cooling is documented in the James Ross Island ice core. Our comparison facilitates more holistic understanding of atmosphere-ocean-cryosphere interactions that may aid predictions of glacial response to future warming and sea-level scenarios.

  5. Pliocene climate along a 42-52° North latitude European transect documented by pollen records

    NASA Astrophysics Data System (ADS)

    Popescu, Speranta-Maria; Biltekin, Demet; Winter, Hanna; Suc, Jean-Pierre; Melinte-Dobrinescu, Mihaela Carmen; Klotz, Stefan; Rabineau, Marina

    2010-05-01

    Climate characteristics (temperature, rainfall, seasonality) of Europe were already documented by several pollen records (Suc et al., 1995; Fauquette et al., 1999; Popescu, 2006; Fauquette et al., 2007; Jiménez-Moreno et al., 2007). Two new pollen records at high chronological resolution of the whole Pliocene (5.33 - 2.6 Ma) and early Pleistocene (DSDP Site 380 in the southwestern Black Sea and Wólka Ligezowska in southern Poland, at 42 and 51° North latitude, respectively), provide detailed information in two key-regions. DSDP Site 380 pollen diagram shows a continuous competition between thermophilous forests and Artemisia steppes, while thermophilous-mesophilous forests contrast with coniferous boreal forests then the latter with toundra-park at Wólka Ligezowska (Popescu et al., accepted). The narrow relationship between Site 380 pollen curves (especially the "thermophilous elements / steppe elements" ratio) and the oxygen isotope reference ones allows (1) to accurately characterize the cyclic evolution of climate progressively leading from warm to glacial conditions along a 10° in latitude gradient in Europe, and (2) to define phytogeographical provinces with their distinction both in mean annual temperature with respect to latitude and in seasonality (temperature, precipitations) according to their geographic location.

  6. Ecological changes in Miocene mammalian record show impact of prolonged climatic forcing.

    PubMed

    Badgley, Catherine; Barry, John C; Morgan, Michèle E; Nelson, Sherry V; Behrensmeyer, Anna K; Cerling, Thure E; Pilbeam, David

    2008-08-26

    Geohistorical records reveal the long-term impacts of climate change on ecosystem structure. A 5-myr record of mammalian faunas from floodplain ecosystems of South Asia shows substantial change in species richness and ecological structure in relation to vegetation change as documented by stable isotopes of C and O from paleosols. Between 8.5 and 6.0 Ma, C(4) savannah replaced C(3) forest and woodland. Isotopic historical trends for 27 mammalian herbivore species, in combination with ecomorphological data from teeth, show three patterns of response. Most forest frugivores and browsers maintained their dietary habits and disappeared. Other herbivores altered their dietary habits to include increasing amounts of C(4) plants and persisted for >1 myr during the vegetation transition. The few lineages that persisted through the vegetation transition show isotopic enrichment of delta(13)C values over time. These results are evidence for long-term climatic forcing of vegetation structure and mammalian ecological diversity at the subcontinental scale. PMID:18711123

  7. Evidence for an early Holocene climate optimum in the Antarctic deep ice-core record

    SciTech Connect

    Ciais, P.; Lipenkov, V.; Nicolaiev, V.

    1992-01-01

    In the interpretation of the Antarctic deep ice-core data, little attention has been given to the Holocene part of the records. As far as translation of the stable isotope content in terms of temperature is concerned, this can be understood because expected temperature changes may be obscured by isotopic noise of various origins and because no {sup 14}C dating has yet been available for this type of sequence. In this article, we focus on the Dome C and Vostok cores and on a new 850-m long ice core drilled out at Komsomolskaia by the Soviet Antarctic Expeditions. These three sites are located in East Antarctica, on the Antarctic plateau, in a region essentially undisturbed by ice-flow conditions, so that their detailed intercomparison may allow us to identify the climatically significant isotopic signal. Our results compare well with the proximal records of Southern Hemisphere high latitudes and support the existence of a warmer {open_quotes}climatic optimum{close_quotes} between 10 and 6 ka y BP. Maximum temperatures are reached just at the end of the last deglaciation, which confirms previous observations at high latitudes, in contrast with later dates for the Atlantic and hypsithermal optima in Europe and North America. 60 refs., 6 figs.

  8. Little Ice Age Glaciation in Alaska: A record of recent global climatic change

    SciTech Connect

    Calkin, P.E.; Wiles, G.C.

    1992-03-01

    General global cooling and temperature fluctuation accompanied by expansion of mountain glaciers characterized the Little Ice Age of about A.D. 1200 through A.D. 1900. The effects of such temperature changes appear first and are strongest at high latitudes. Therefore the Little Ice Age record of glacial fluctuation in Alaska may provide a good proxy for these events and a test for models of future climatic change. Holocene expansions began here as early as 7000 B.P. and locally show a periodicity of 350 years after about 4500 years B.P. The Little Ice Age followed a late Holocene interval of minor ice advance and a subsequent period of ice margin recession lasting one to seven centuries. The timing of expansions since about A.D. 1200 have often varied between glaciers, but these are the most pervasive glacial events of the Holocene in Alaska and frequently represent ice marginal maxima for this interval. At least two major expansions are, apparent in forefields of both land-terminating and fjord-calving glaciers, but the former display the most reliable and detailed climatic record. Major maxima occurred by the 16th century and into the mid-18th century. Culmination of advances occurred throughout Alaska during the 19th century followed within a few decades by general glacial retreat. Concurrently, equilibrium line altitudes have been raised 100-400 m, representing a rise of 2-3 deg C in mean summer temperature.

  9. Ecological changes in Miocene mammalian record show impact of prolonged climatic forcing

    PubMed Central

    Badgley, Catherine; Barry, John C.; Morgan, Michèle E.; Nelson, Sherry V.; Behrensmeyer, Anna K.; Cerling, Thure E.; Pilbeam, David

    2008-01-01

    Geohistorical records reveal the long-term impacts of climate change on ecosystem structure. A 5-myr record of mammalian faunas from floodplain ecosystems of South Asia shows substantial change in species richness and ecological structure in relation to vegetation change as documented by stable isotopes of C and O from paleosols. Between 8.5 and 6.0 Ma, C4 savannah replaced C3 forest and woodland. Isotopic historical trends for 27 mammalian herbivore species, in combination with ecomorphological data from teeth, show three patterns of response. Most forest frugivores and browsers maintained their dietary habits and disappeared. Other herbivores altered their dietary habits to include increasing amounts of C4 plants and persisted for >1 myr during the vegetation transition. The few lineages that persisted through the vegetation transition show isotopic enrichment of δ13C values over time. These results are evidence for long-term climatic forcing of vegetation structure and mammalian ecological diversity at the subcontinental scale. PMID:18711123

  10. Carbonaceous aerosol tracers in ice-cores record multi-decadal climate oscillations

    PubMed Central

    Seki, Osamu; Kawamura, Kimitaka; Bendle, James A. P.; Izawa, Yusuke; Suzuki, Ikuko; Shiraiwa, Takayuki; Fujii, Yoshiyuki

    2015-01-01

    Carbonaceous aerosols influence the climate via direct and indirect effects on radiative balance. However, the factors controlling the emissions, transport and role of carbonaceous aerosols in the climate system are highly uncertain. Here we investigate organic tracers in ice cores from Greenland and Kamchatka and find that, throughout the period covered by the records (1550 to 2000 CE), the concentrations and composition of biomass burning-, soil bacterial- and plant wax- tracers correspond to Arctic and regional temperatures as well as the warm season Arctic Oscillation (AO) over multi-decadal time-scales. Specifically, order of magnitude decreases (increases) in abundances of ice-core organic tracers, likely representing significant decreases (increases) in the atmospheric loading of carbonaceous aerosols, occur during colder (warmer) phases in the high latitudinal Northern Hemisphere. This raises questions about causality and possible carbonaceous aerosol feedback mechanisms. Our work opens new avenues for ice core research. Translating concentrations of organic tracers (μg/kg-ice or TOC) from ice-cores, into estimates of the atmospheric loading of carbonaceous aerosols (μg/m3) combined with new model constraints on the strength and sign of climate forcing by carbonaceous aerosols should be a priority for future research. PMID:26411576

  11. Multi-proxy records of Eocene vegetation and climatic dynamics from North America

    NASA Astrophysics Data System (ADS)

    Sheldon, N. D.; Smith, S. Y.; Stromberg, C. A.; Hyland, E.; Miller, L. A.

    2010-12-01

    The Eocene is characterized by a “thermal maximum” in the early part, and a shift to “icehouse” conditions by the end of the epoch. Consequently, this is an interesting time to look at vegetation dynamics and understanding plant responses to environmental change, especially as refinement of global climate models is needed if we are to understand future climate change impacts. Paleobotanical evidence, such as phytoliths (plant silica bodies), and paleoenvironmental indicators, such as paleosols, offer an opportunity to study vegetation composition and dynamics in the absence of macrofossils on a variety of spatial and temporal scales. To examine the interaction between paleoclimatic/paleoenvironmental changes and paleovegetation changes, we will compare and contrast two well-dated, high-resolution, multi-proxy records from North America. The margins of the Green River Basin system during the Early Eocene Climatic Optimum (53-50 Ma) are an extremely important location for understanding ecological composition and potential climatic drivers of North American floral diversification, because this area is widely considered the point of origin for many modern grass clades. We examined paleosols preserved in the fluvial, basin-margin Wasatch Formation preserved near South Pass, Wyoming. Field identification of the paleosols indicated a suite that includes Entisols, Inceptisols, and Alfisols. To reconstruct paleovegetation, pedogenic carbonates were analyzed isotopically, and samples were collected and extracted for phytoliths . By combining these paleobotanical proxies with quantitative climatic proxies on whole rock geochemistry, we will present an integrated vegetation-climate history of the EECO at the margins of the Green River Basin. Second, we will present high-resolution record of vegetation patterns based on phytoliths from a section of the Renova Formation, Timberhills region, Montana dated to 39.2 ± 3 Ma. The section is composed of Alfisols, Entisols

  12. KZai 02 pollen record, an insight into West African monsoon fluctuations during the Last Climatic Cycle

    NASA Astrophysics Data System (ADS)

    Dalibard, M.; Popescu, S.; Maley, J.; Suc, J.

    2012-12-01

    Climate of the circum-Atlantic intertropical zone is driven by the ocean/atmosphere dynamics in response to variations of yearly insolation. These latitudes correspond to the convergence of the Hadley cells expressed on earth surface by intense trade winds and in lower troposphere by the African easterly jet making the edges of the intertropical zone relatively dry, while humidity is concentrated near the Equator. This phenomenon generates a precipitation front, known as the InterTropical Convergence Zone (ITCZ), the oscillations of which regulate the latitudinal vegetation distribution. Pollen record of core KZai 02 (Guinea Gulf) allows high resolution reconstruction of variations of past ecosystems over Central Africa during the Last Climatic Cycle. Plant taxa recorded in pollen analyses have been clustered according to their ecological requirements and African phytogeography. Fluctuations of these groups inform on precipitation intensity and their distribution during the last 130 ka. During Glacials, an open vegetation made of Cyperaceae marshes developed in the central Zaire/Congo Basin, surrounded by savannah on borders and afromontane forests on reliefs. Composition and distribution of vegetation indicate a decrease in monsoon activity and the strengthening of the precipitation front in the center of the basin. Interglacial phases are characterized by rain forest expansion over Central Africa in response to a precipitation enhancement associated with a northward shift of the rainfall front. Replacement of afromontane forest and marsh ecosystems by savannah then lowland pioneering, warm-temperate and rain forests characterized glacial/interglacial transitions. This succession suggests the increasing influence of at least two climatic parameters: the water availability and temperature and/or CO2 fluctuation. Spectral analysis applied to vegetation groups evidences the forcing of insolation, mainly driven by precession, on the West African monsoon system. Sub

  13. The Integration of SMOS Soil Moisture in a Consistent Soil Moisture Climate Record

    NASA Astrophysics Data System (ADS)

    de Jeu, Richard; Kerr, Yann; Wigneron, Jean Pierre; Rodriguez-Fernandez, Nemesio; Al-Yaari, Amen; van der Schalie, Robin; Dolman, Han; Drusch, Matthias; Mecklenburg, Susanne

    2015-04-01

    Recently, a study funded by the European Space Agency (ESA) was set up to provide guidelines for the development of a global soil moisture climate record with a special emphasis on the integration of SMOS. Three different data fusion approaches were designed and implemented on 10 year passive microwave data (2003-2013) from two different satellite sensors; the ESA Soil Moisture Ocean Salinity Mission (SMOS) and the NASA/JAXA Advanced Scanning Microwave Radiometer (AMSR-E). The AMSR-E data covered the period from January 2003 until Oct 2011 and SMOS data covered the period from June 2010 until the end of 2013. The fusion approaches included a neural network approach (Rodriguez-Fernandez et al., this conference session HS6.4), a regression approach (Wigneron et al., 2004), and an approach based on the baseline algorithm of ESAs current Climate Change Initiative soil moisture program, the Land Parameter Retrieval Model (Van der Schalie et al., this conference session HS6.4). With this presentation we will show the first results from this study including a description of the different approaches and the validation activities using both globally covered modeled datasets and ground observations from the international soil moisture network. The statistical validation analyses will give us information on the temporal and spatial performance of the three different approaches. Based on these results we will then discuss the next steps towards a seamless integration of SMOS in a consistent soil moisture climate record. References Wigneron J.-P., J.-C. Calvet, P. de Rosnay, Y. Kerr, P. Waldteufel, K. Saleh, M. J. Escorihuela, A. Kruszewski, 'Soil Moisture Retrievals from Bi-Angular L-band Passive Microwave Observations', IEEE Trans. Geosc. Remote Sens. Let., vol 1, no. 4, 277-281, 2004.

  14. Geomorphological records of extreme floods and their relationship to decadal-scale climate change

    NASA Astrophysics Data System (ADS)

    Foulds, S. A.; Griffiths, H. M.; Macklin, M. G.; Brewer, P. A.

    2014-07-01

    Extreme rainfall and flood events in steep upland catchments leave geomorphological traces of their occurrence in the form of boulder berms, debris cones, and alluvial fans. Constraining the age of these features is critical to understanding (i) landscape evolution in response to past, present, and future climate changes; and (ii) the magnitude-frequency of extreme, ungauged floods in small upland catchments. This research focuses on the Cambrian Mountains of Wales, UK, where lichenometric dating of geomorphological features and palaeohydrological reconstructions is combined with climatological data and documentary flood records. Our new data from Wales highlight a distinct flood-rich period between 1900 and 1960, similar to many other UK lichen-dated records. However, this study sheds new light on the underlying climatic controls on upland flooding in small catchments. Although floods can occur in any season, their timing is best explained by the Summer North Atlantic Oscillation (SNAO) and shifts between negative (wetter than average conditions with regular cyclonic flow and flooding) and positive phases (drier than average conditions with less frequent cyclonic flow and flooding), which vary from individual summers to decadal and multidecadal periods. Recent wet summer weather, flooding, and boulder-berm deposition in the UK (2007-2012) are related to a pronounced negative phase shift of the SNAO. There is also increasing evidence that recent summer weather extremes in the mid-latitudes may be related to Arctic amplification and rapid sea ice loss. If this is the case, continuing and future climate change is likely to mean that (i) unusual weather patterns become more frequent; and (ii) upland UK catchments will experience heightened flood risk and significant geomorphological changes.

  15. Long-range persistence of temperature records induced by long-term climatic phenomena.

    PubMed

    Capparelli, V; Vecchio, A; Carbone, V

    2011-10-01

    The occurrence of persistence in climatic systems has been investigated by analyzing 1167 surface temperature records, covering 110 years, in the whole United States. Due to the nonlinear and nonstationary character of temperature time series, the seasonal cycle suffers from both phase and amplitude modulations, which are not properly removed by the classical definition of the temperature anomaly. In order to properly filter out the seasonal component and the monotonic trends, we define the temperature anomaly in a different way by using the empirical mode decomposition (EMD). The essence of this method is to empirically identify the intrinsic oscillatory modes from the temperature records according to their characteristic time scale. The original signal is thus decomposed into a collection of a finite small number of intrinsic mode functions (IMFs), having its own time scale and representing oscillations experiencing amplitude and phase modulations, and a residue, describing the mean trend. The sum of all the IMF components as well as the residue reconstructs the original signal. Partial reconstruction can be achieved by selectively choosing IMFs in order to remove trivial trends and noise. The EMD description in terms of time-dependent amplitude and phase functions overcomes one of the major limitation of the Fourier analysis, namely, a correct description of nonlinearities and nonstationarities. By using the EMD definition of temperature anomalies we found persistence of fluctuations with a different degree according to the geographical location, on time scales in the range 3-15 years. The spatial distribution of the detrended fluctuation analysis exponent, used to quantify the degree of memory, indicates that the long-term persistence could be related to to the presence of climatic regions, which are more sensitive to climatic phenomena such as the El Niño southern oscillation. PMID:22181223

  16. Toward understanding nonstationarity in climate and hydrology through tree ring proxy records

    NASA Astrophysics Data System (ADS)

    Razavi, Saman; Elshorbagy, Amin; Wheater, Howard; Sauchyn, David

    2015-03-01

    Natural proxy records of hydroclimatic behavior, such as tree ring chronologies, are a rich source of information of past climate-driven nonstationarities in hydrologic variables. In this study, we investigate tree ring chronologies that demonstrate significant correlations with streamflows, with the objective of identifying the spatiotemporal patterns and extents of nonstationarities in climate and hydrology, which are essentially representations of past "climate changes." First and second-order nonstationarities are of particular interest in this study. As a prerequisite, we develop a methodology to assess the consistency and credibility of a regional network of tree ring chronologies as proxies for hydrologic regime. This methodology involves a cluster analysis of available tree ring data to understand and evaluate their dependence structure, and a regional temporal-consistency plot to assess the consistency of different chronologies over time. The major headwater tributaries of the Saskatchewan River basin (SaskRB), the main source of surface water in the Canadian Prairie Provinces, are used as the case study. Results indicate that stationarity might never have existed in the hydrology of the region, as the statistical properties of annual paleo-hydrologic proxy records across the basin, i.e., the mean and autocorrelation structure, have consistently undergone significant changes (nonstationarities) at different points in the history of the region. The spatial pattern of the changes in the mean statistic has been variable with time, indicating a time-varying cross-correlation structure across the tributaries of the SaskRB. Conversely, the changes in the autocorrelation structure across the basin have been in harmony over time. The results demonstrate that the 89 year period of observational record in this region is a poor representation of the long-term properties of the hydrologic regime, and shorter periods, e.g., 30 year periods, are by no means

  17. Total Uncertainty in Measurements Record for Climate: Strategies from the CLARREO Mission

    NASA Astrophysics Data System (ADS)

    Dykema, J. A.; Anderson, J.

    2010-12-01

    Questions about uncertainty in observed trends in the climate system arise from multiple sources, including instrument performance, issues of temporal and spatial sampling, and geophysical information content obtainable from measurement records. The Climate Absolute Radiance and Refractivity Observatory (CLARREO) mission is designed to provide objective, testable evidence to support uncertainty estimates associated with these various sources. In this paper, we examine the strategies planned for CLARREO to obtain the information required to achieve this objective. In the case of instrument performance, the CLARREO sensors will utilize methods for obtaining robust uncertainty estimates that have been refined throughout the natural sciences through the work of the international community of National Measurement Institutes (NMIs). The foundation of the methods developed by the NMI community is a set of measurement standards that can be reproduced over time, and across national borders and institutions, to assure an exact quantitative relationship between different measurements. These measurement standards are the International System of Units, or SI. The SI units achieve the required properties by utilizing fundamental properties of matter to define a measurement system that is independent of instruments or techniques that are specific to a particular place or time. The set of a robust set of measurement standards then forms the basis for an experimental strategy to test the uncertainty of a climate observation system based on objective techniques that can be repeated by any experimenter, anywhere in the world, at any time. This paper will look at specific examples of the physical logic underlying this framework for the CLARREO infrared instrument suite, paying special attention to the overlap between the CLARREO calibration strategies and measurement successes from other areas of natural science. The interplay of measurement uncertainty with sampling and information

  18. Multi-decadal-scale records of North Atlantic climate variability during the last and present interglacials and preceding glacial terminations.

    NASA Astrophysics Data System (ADS)

    Jimenez-Amat, Patricia; Zahn, Rainer

    2013-04-01

    High-resolution records of natural interglacial climate variability can provide knowledge if the currently ongoing climate change and variability are part of or are already beyond the natural state. Warmer-than-present climatic conditions, a reduced Greenland Ice Sheet and higher sea level are some of the features the Last Interglacial (LIG, MIS5e; 129-115 kyr) climate has in common with numerous model projections of our future climate (Otto-Bliesner et al., 2006; Koop et al., 2009). Establishing multi-decadal resolution records of past North Atlantic climate variability hence contributes to a better understanding of the ocean and climate sensitivity of the wider North Atlantic region. We present palaeoceanographic time series of surface ocean climatology from Ocean Drilling Program (ODP) Site 976 in the Alboran Sea, westernmost Mediterranean that span the LIG and Present Interglacial (PIG, Holocene, 11-0 kyr). The site receives North Atlantic climate signals through the atmosphere and with the advection of Atlantic inflow waters which in connection with the high rate of sediment deposition underscores the exceptional quality of the site to monitor North Atlantic climate variability at multi-decadal resolution (60-90 yrs). Sea surface temperature (SST) time series derived from Mg/Ca ratios and stable isotope records (δ18O, δ13C) of the planktonic foraminifera Globigerina bulloides are presented. Mg/Ca data display similar SST for the climatic optima PIG and LIG. The records compare well with speleothem and ice core palaeoclimatic profiles, confirming that Site 976 palaeo-profiles reflect climate of the North Atlantic region. The close link between SSTMg-Caand the LIG δ18O record from the Antro del Corchia speleothem in northern Italy highlights the strong connection between marine and terrestrial climatology during that time indicating a farfield contribution of atmospheric signals. Comparison with SST and benthic δ13C records at North Atlantic sites instructs

  19. Glacial to Interglacial Climate and Sea Level Changes Recorded in Submerged Speleothems, Argentarola, Italy

    NASA Astrophysics Data System (ADS)

    Folz-Donahue, K.; Dutton, A.; Antonioli, F.; Richards, D. A.; Nita, D. C.; Lambeck, K.

    2014-12-01

    Direct records of Quaternary sea level change can provide insight on the timing and nature of ice sheet retreat during glacial terminations. Such records are generally rare, particularly prior to the last deglaciation, due in part to the difficulty of recovering material from sites that have been submerged by subsequent sea-level rise. A suite of stalagmites recovered from a submerged cave on Argentarola Island in the Tyrrhenian Sea contains hiatuses that were formed when the cave became submerged by seawater. These hiatuses are remarkable due to the presence of calcite tubes secreted by serpulid worms, providing direct evidence of marine inundation. As sea level drops during the following glacial inception, the cave is drained and dense spelean calcite encases the serpulid worm tubes, forming alternating layers of spelean and serpulid calcite. U-Th dates of spelean calcite directly above and below these serpulid layers has previously been used to constrain timing and amplitude of sea level highstands in the Mediterranean. Stable isotope records from the same cave have also been used to indicate increased precipitation across the Mediterranean during Sapropel 6 (175 ka). Here we present U-Th dates and stable isotope records for three Argentarola stalagmites. These specimens were recovered from -22, -18, and -14 m relative to present sea level (rpsl), and complement previously published data for Argentarola stalagmites at -21, -18.5, and -18 m rpsl. The timing and elevation of spelean calcite directly above and below serpulid tube layers provide rare insight on rates of sea-level change between -14 and -22 m during glacial terminations and inceptions prior to the last termination. Stable isotope records from the same stalagmites are used to investigate changes in western Mediterranean climate and potential relationships to Mediterranean sapropel events.

  20. A Bat's-Eye View of Holocene Climate Change in the Southwest: Resolving Ambiguities in Cave Isotopic Records

    NASA Astrophysics Data System (ADS)

    Cole, J. E.; Truebe, S. A.; Harrington, M. D.; Woodhead, J. D.; Overpeck, J. T.; Hlohowskyj, S.; Henderson, G. M.

    2015-12-01

    In dry environments, speleothems provide an outstanding archive of information on past climate change, particularly since lakes are typically absent or intermittent. Speleothem stable isotopes are widely used for climate reconstruction, but the isotope-climate relationship is complex in arid-region precipitation, and within-cave processes further complicate climate interpretations. Our isotope results from 3 southeastern Arizona caves, spanning the past 3.5-12 kyr, collectively indicate a weakening monsoon from 7kyr to present. These records exhibit substantial multidecadal-multicentury variability that is sometimes shared, and sometimes independent among caves. Strategies to overcome ambiguities in isotope records include long-term monitoring of cave dripwaters, multi-site comparisons, and multiproxy measurements. Monthly dripwater measurements from two caves spanning several years highlight substantial seasonal biases that create distinct differences in the climate sensitivity of individual cave records. These biases can lead to lack of correlation between records, but also creates opportunities for seasonally specific moisture reconstructions. New preliminary analyses suggest that elemental data can help to unravel the multivariate signal contained in speleothem oxygen isotope records.

  1. A Quarter Century Record of Stratospheric Sulfate Aerosol: implication for the past, present and future climates

    NASA Astrophysics Data System (ADS)

    Shaheen, R.; Abaunza, M.; Jackson, T. L.; McCabe, J.; Savarino, J.; Thiemens, M. H.

    2014-12-01

    Stratospheric sulfate aerosol (SSA) plays an important role in the earth climate system by reflecting solar radiation making it an attractive candidate in geoengineering to counter greenhouse warming. However, these planetary scales perturbations demand a priori understanding of SSA over a longer time period to resolve anthropogenic and natural perturbations to the delicate and thin layers- SSA and ozone layers. Here we present a quarter century high resolution seasonal record of SSA and its linkage to the ozone layer. Sulfate was extracted from a (1x1m) and 25m deep snow pit at the South Pole. The combination of cations, anions, O-triple isotopes and S-quadruple isotope measurements allowed us to deconvolve the oxidation history of SSA and tease out natural and anthropogenic components. The period (1980 to 2002) encompasses the largest volcanic eruptions of the century, El-Chichon, Pinatubo, Cerro Hudson and the three largest El-Nino Southern Oscillation events. The highest O-isotope anomaly (∆17O = 3.7‰) in SSA was observed during the super ENSO event (1997-98) and recorded changes in ozone levels of the upper troposphere-lower stratosphere (1). ENSO is another flavor of natural climate variability and is important as it links hydrosphere and the atmosphere in unique ways controlling rainfall and temperature. The highest S-isotope anomaly was observed in 1998-99 and records changes in atmospheric dynamics and transport of sulfur compounds to the stratosphere following intense wild fires as a consequence of the Super ENSO event. The highest S-isotopic anomaly (∆33S = +2.26‰ and ∆36S= +0.51 ‰) is ~ 3 times higher compared to the Pinatubo signal, the largest volcanic eruption of the 20th century. The pattern of S-isotope anomalies in this period fits within the pre-Cambrian record of S-isotopes in three billion year old rock. The generation of such a large S-isotope anomaly in the present day oxygen rich atmosphere may have implications for the

  2. Late Holocene climatic changes in west Africa, a high resolution diatom record from equatorial Cameroon

    NASA Astrophysics Data System (ADS)

    Nguetsop, Victor François; Servant-Vildary, Simone; Servant, Michel

    2004-03-01

    Holocene climatic changes in West Africa are usually explained by increased/decreased activity of the monsoon from the Guinean Gulf toward the continent. According to a diatom record from Lake Ossa (3°50'N, 9°36'E), we suggest that, in the near coastal areas of Cameroon, phases of intensification of the monsoon were marked by reduced precipitation and reduced evaporation, conditions nowadays prevailing South of the equator (4-5°S) during the austral winter. Lake Ossa is a shallow lake located in one of the rainiest area of the African rain forest belt. During the wet season (March-November) it is fed by acid meteoric waters entailing low pH in the lacustrine waters. During the dry season (December-February) groundwater discharges allow the persistence of acid waters near the borders of the lake, but, in the inner parts, the waters tend to be alkaline, alkaliphilous diatoms are abundant in the surface sediment samples and are used as indicators of low precipitation. At that time, atmospheric dust containing reworked diatoms from Saharan Quaternary deposits is transported by the northern trade winds and reaches the Ossa area. Wind blown diatoms are considered as a signature of the northern trade winds. A diatom record from the western deep part of Lake Ossa has provided climatic data for the mid-late Holocene at a resolution of 50-60 years. A major climatic change at 2700 cal yr BP was marked by the appearance of wind blown diatoms. A millennial-scale alternation between low and high precipitation episodes is recorded during the last 5500 years. The low precipitation episodes before 2700 cal yr BP are interpreted as a consequence of a northward extension of the climatic conditions that nowadays characterize the Southern Congo during the austral winter, when the monsoon extends into West Africa and reaches the northern sub-tropical latitudes. The effects of low precipitation on the water balance and on the rain forest were obliterated by an extremely low

  3. Regional climate model-speleothem proxy record comparisons for the last deglaciation in California.

    NASA Astrophysics Data System (ADS)

    Oster, J. L.; Montanez, I. P.; Potter, G. L.; Behling, P.; Bauer, M.; Rosenbloom, N. A.; Otto-Bliesner, B. L.

    2012-12-01

    Both ecosystems and human populations in western North America depend on seasonal precipitation delivered by winter storms originating in the Pacific Ocean. Understanding the history of water availability and storminess in western North America is imperative to better anticipate the impacts of future climate change in this water-stressed region. Proxy records and climate models suggest that water availability in this region varied substantially during the late Pleistocene and Holocene. However, the spatial and temporal patterns of this variability as well as the mechanisms behind it remain poorly constrained. Here we present a comparison of speleothem-based paleoclimate proxy records from Moaning Cave, central Sierra Nevada, California with results from a transient simulation of the climate evolution from the Last Glacial Maximum (21 ka) to the early Holocene (10 ka) carried out using the coupled atmosphere-ocean general circulation model, the Community Climate System Model version 3 (CCSM3). With realistic time-varying boundary conditions and forcings, the model successfully simulates the deglacial climate evolution of the North Atlantic region, including the collapse of AMOC. Records of stable isotope (δ18O and δ13C) and trace element concentration (Mg, Sr) variations in the Moaning Cave speleothem suggest drier and warmer conditions above the cave during past Northern Hemisphere warm periods and wetter and colder conditions during past Northern Hemisphere cold periods between 8.7 and 16.7 ka. Two discrete time slices representing the maximum (during the Bølling, 14.37 ka) and minimum (during the Younger-Dryas, 12.2 ka) stable isotope values observed during this time interval in the Moaning Cave record (and thus potentially the driest and wettest conditions above the cave, respectively) were selected, regridded to a higher resolution (T85; 1.4ο atmosphere) and run for short time slices (15 - 20 years) using the Community Atmosphere Model (CAM), which

  4. Climate Forcing on the Sedimentary Pb Isotope Record of the Equatorial Atlantic

    NASA Astrophysics Data System (ADS)

    Abouchami, W.; Zabel, M.

    2001-12-01

    The forcing mechanism for the radiogenic isotopes variations recorded in marine sediments over the past few million years remains debatable and a causal link between isotope tracers and climate is difficult to ascertain. We report evidence for a climate control on Pb sources to the Equatorial Atlantic using high precision Pb triple spike data (Galer, 1999) on two sediments cores covering the last six Marine Isotope Stages ( ~200 ka). Core GeoB1523-1 (3° 49,9'N, 41° 37.3'W, 3292m) is located on the Ceará Rise (West Atlantic) close to the Amazon mouth and core GeoB2910-1 (4° 50.7'N, 21° 03.2'W, 2703m) on the Sierra Leone Rise (East Atlantic) on the downwind trajectory of the boreal winter Saharan dust plume. These cores are ideally situated for monitoring climate-related Pb isotopic variations, since they have been shown to record past variations in terrigenous fluxes in response to Earth's orbital changes (Zabel et al., 1999; Rühlemann et al., 2001). Pb isotope data were obtained on bulk sediments which, given the two orders of magnitude difference in Pb contents of detritus ( ~10ppm) and carbonate (1-10ppb), will essentially reflect the composition of the terrigenous fraction. Pb isotope ratios display periodic fluctuations over the last ~200 ka in both cores and are quite distinct in the two basins. The east Atlantic core exhibits higher 207Pb/204Pb and 208Pb/204Pb but lower 206Pb/204Pb than the west Atlantic core. The Pb isotope signal is cyclical and closely follows the \\delta 18O record, interglacial periods being systematically more radiogenic than glacial periods. This pattern is observed in both cores, although changes in the western Atlantic seem to lead those in the eastern Atlantic. In Pb isotope space, the west Atlantic data form a unique Pb isotope array that is quite distinct from the east Atlantic where two trends are found. This clearly demonstrates that the Pb sources feeding the two basins are different. Furthermore, the persistence of a

  5. Climatic stress events in the source region of modern man - Matching the last 20 ka of the Chew Bahir climate record with occupation history of adjacent refugia

    NASA Astrophysics Data System (ADS)

    Foerster, Verena; Vogelsang, Ralf; Junginger, Annett; Asrat, Asfawossen; Lamb, Henry F.; Viehberg, Finn; Trauth, Martin H.; Schaebitz, Frank

    2014-05-01

    A rapidly changing environment is considered an important driver not just for human evolution but also for cultural and technological innovation and migration. To evaluate the impact that climatic shifts on different timescales might have had on the living conditions of prehistoric humans is one of the cornerstones in current research, but continuous paleo-climate records in the vicinity of archaeological sites are still rare. As a contribution towards a better understanding of this human-climate interaction we here present a match between the last 20 ka of the just recently developed paleo-climate record from Chew Bahir in southern Ethiopia and the settlement history of adjacent possible refugia. The Chew Bahir basin, as a newly explored reliable climatic archive, lies in a biogeographically highly sensitive transition zone between the Main Ethiopian Rift and the Omo-Turkana basin and hence represents an ideal site to study climatic variability in the source region of modern man. The climatic history with a temporal resolution of up to 3 years is showing besides orbitally driven long-term transitions in and out of favourable living conditions several short abrupt excursions towards drier or wetter episodes. Comparing the frequency of archaeological findings as a parameter for human occupation to this close-by climate record that allows us to outline how complex the interplay between humans and environment during the last 20 ka really was, which dynamics might have been involved and which role the temporal dimension of environmental changes could have played for the adaption of humans.

  6. A 250,000-year climatic record from great basin vein calcite: Implications for Milankovitch theory

    USGS Publications Warehouse

    Winograd, I.J.; Szabo, B. J.; Coplen, T.B.; Riggs, A.C.

    1988-01-01

    A continuous record of oxygen-18 (??18O) variations in the continental hydrosphere during the middle-to-late Pleistocene has been obtained from a uranium-series dated calcitic vein in the southern Great Basin. The vein was deposited from ground water that moved through Devils Hole - an open fault zone at Ash Meadows, Nevada - between 50 and 310 ka (thousand years ago). The configuration of the ??18O versus time curve closely resembles the marine and Antarctic ice core (Vostok) ??18O curves; however, the U-Th dates indicate that the last interglacial stage (marine oxygen isotope stage 5) began before 147 ?? 3 ka, at least 17,000 years earlier than indicated by the marine ??18O record and 7,000 years earlier than indicated by the less well dated Antarctic ??18O record. This discrepancy and other differences in the timing of key climatic events suggest that the indirectly dated marine ??18O chronology may need revision and that orbital forcing may not be the principal cause of the Pleistocene ice ages.

  7. Organic matter preservation: A proxy for Turonian climatic shifts recorded during relative sea-level stillstands

    SciTech Connect

    White, T.S.; Arthur, M.A.; Dean, W.

    1996-12-31

    We performed analyses of organic matter obtained from cores across Utah, Colorado, and Kansas. The results provide a detailed (30 cm sampling interval) record of organic matter preservation in the Turonian seaway during highstand (HST), lowstand (LST) and overlying transgressive systems tract (TST) deposition in the Western Interior Seaway. In general, total organic carbon (TOC) and carbonate (CaCO3) percentages decrease through the HST, with the highest values obtained from strata deposited during maximum transgression. Organic matter within the early- to mid-HST is dominantly marine algae with dinoflagellate and foraminiferal inputs. The late-HST contains small quantities of TOC and CaCO3, characterized as terrestrial organic debris; early-LST sediments have a signature similar to the late-HST. As one might expect, during sea-level fall the basin records mostly terrestrial inputs, whereas during sea-level rise a marine signature prevails. A similarity exists between late-LST and early-HST TOC and CaCO3 contents and is noteable for fluctuations between terrestrial and marine organic matter as indicated by Rockeval pyrolyses, organic petrography, and palynology. We surmise that during mid-HST and late-LST (i.e. during times of little or no variation in rate of sea-level change), the basin is poised to record fluctuations between terrestrial and marine-dominated sediment deposition which may be controlled by changes in climate.

  8. Warm Events At Summit, Greenland During 2012 Relative To An Evolving Climate Record

    NASA Astrophysics Data System (ADS)

    Shuman, C. A.; Schnaubelt, M. J.; Mefford, T. K.

    2012-12-01

    An evolving temperature record from the Greenland Summit Station, at approximately 3216 m in elevation, has documented unusual periods of near and above freezing air temperatures in July 2012. Since August 2005, data has been collected from well-calibrated and actively-ventilated temperature sensors at a NOAA-ESRL climate observatory. Comparison of these data from a nominal 2 m height above the ice sheet surface over the past seven summers reveals several periods of unusual warmth at the highest elevations of the ice sheet in 2012. Detailed analysis of the available data indicates that temperatures rose to or above freezing for almost 6.5 hours on July 11 at Summit Station. A maximum air temperature of 1 degree C was recorded repeatedly in the 1-minute averages during this period. NOAA's data also indicated brief periods at or above zero on July 12th and 29th as well. These anomalously warm air-temperature periods can now be compared and contrasted with equivalent-quality data from earlier records (automatic weather stations began operating in May 1987 during the GISP2 project) and used to calibrate indications of warm surface temperatures derived from multi-decadal satellite passive microwave and infrared sensors.

  9. Organic matter preservation: A proxy for Turonian climatic shifts recorded during relative sea-level stillstands

    SciTech Connect

    White, T.S.; Arthur, M.A. ); Dean, W. )

    1996-01-01

    We performed analyses of organic matter obtained from cores across Utah, Colorado, and Kansas. The results provide a detailed (30 cm sampling interval) record of organic matter preservation in the Turonian seaway during highstand (HST), lowstand (LST) and overlying transgressive systems tract (TST) deposition in the Western Interior Seaway. In general, total organic carbon (TOC) and carbonate (CaCO3) percentages decrease through the HST, with the highest values obtained from strata deposited during maximum transgression. Organic matter within the early- to mid-HST is dominantly marine algae with dinoflagellate and foraminiferal inputs. The late-HST contains small quantities of TOC and CaCO3, characterized as terrestrial organic debris; early-LST sediments have a signature similar to the late-HST. As one might expect, during sea-level fall the basin records mostly terrestrial inputs, whereas during sea-level rise a marine signature prevails. A similarity exists between late-LST and early-HST TOC and CaCO3 contents and is noteable for fluctuations between terrestrial and marine organic matter as indicated by Rockeval pyrolyses, organic petrography, and palynology. We surmise that during mid-HST and late-LST (i.e. during times of little or no variation in rate of sea-level change), the basin is poised to record fluctuations between terrestrial and marine-dominated sediment deposition which may be controlled by changes in climate.

  10. A 250,000-Year Climatic Record from Great Basin Vein Calcite: Implications for Milankovitch Theory

    NASA Astrophysics Data System (ADS)

    Winograd, Isaac J.; Szabo, Barney J.; Coplen, Tyler B.; Riggs, Alan C.

    1988-12-01

    A continuous record of oxygen-18 (δ 18O) variations in the continental hydrosphere during the middle-to-late Pleistocene has been obtained from a uranium-series dated calcitic vein in the southern Great Basin. The vein was deposited from ground water that moved through Devils Hole--an open fault zone at Ash Meadows, Nevada--between 50 and 310 ka (thousand years ago). The configuration of the δ 18O versus time curve closely resembles the marine and Antarctic ice core (Vostok) δ 18O curves; however, the U-Th dates indicate that the last interglacial stage (marine oxygen isotope stage 5) began before 147 ± 3 ka, at least 17,000 years earlier than indicated by the marine δ 18O record and 7,000 years earlier than indicated by the less well dated Antarctic δ 18O record. This discrepancy and other differences in the timing of key climatic events suggest that the indirectly dated marine δ 18O chronology may need revision and that orbital forcing may not be the principal cause of the Pleistocene ice ages.

  11. A 250,000-year climatic record from great basin vein calcite: implications for milankovitch theory.

    PubMed

    Winograd, I J; Coplen, T B; Szabo, B J; Riggs, A C

    1988-12-01

    A continuous record of oxygen-18 (delta(18)O) variations in the continental hydrosphere during the middle-to-late Pleistocene has been obtained from a uranium-series dated calcitic vein in the southern Great Basin. The vein was deposited from ground water that moved through Devils Hole-an open fault zone at Ash Meadows, Nevada-between 50 and 310 ka (thousand years ago). The configuration of the delta(18)O versus time curve closely resembles the marine and Antarctic ice core (Vostok) delta(18)O curves; however, the U-Th dates indicate that the last interglacial stage (marine oxygen isotope stage 5) began before 147 +/- 3 ka, at least 17,000 years earlier than indicated by the marine delta(18)O record and 7,000 years earlier than indicated by the less well dated Antarctic delta(18)O record. This discrepancy and other differences in the timing of key climatic events suggest that the indirectly dated marine delta(18)O chronology may need revision and that orbital forcing may not be the principal cause of the Pleistocene ice ages. PMID:17817073

  12. Rapid climate fluctuations over the past millennium: evidence from a lacustrine record of Basomtso Lake, southeastern Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Li, Kai; Liu, Xingqi; Herzschuh, Ulrike; Wang, Yongbo

    2016-04-01

    Abrupt climate changes and fluctuations over short time scales are superimposed on long-term climate changes. Understanding rapid climate fluctuations at the decadal time scale over the past millennium will enhance our understanding of patterns of climate variability and aid in forecasting climate changes in the future. In this study, climate changes on the southeastern Tibetan Plateau over the past millennium were determined from a 4.82-m-long sediment core from Basomtso Lake. At the centennial time scale, the Medieval Climate Anomaly (MCA), Little Ice Age (LIA) and Current Warm Period (CWP) are distinct in the Basomtso region. Rapid climate fluctuations inferred from five episodes with higher sediment input and likely warmer conditions, as well as seven episodes with lower sediment input and likely colder conditions, were well preserved in our record. These episodes with higher and lower sediment input are characterized by abrupt climate changes and short time durations. Spectral analysis indicates that the climate variations at the centennial scale on the southeastern Tibetan Plateau are influenced by solar activity during the past millennium.

  13. Rapid climate fluctuations over the past millennium: evidence from a lacustrine record of Basomtso Lake, southeastern Tibetan Plateau.

    PubMed

    Li, Kai; Liu, Xingqi; Herzschuh, Ulrike; Wang, Yongbo

    2016-01-01

    Abrupt climate changes and fluctuations over short time scales are superimposed on long-term climate changes. Understanding rapid climate fluctuations at the decadal time scale over the past millennium will enhance our understanding of patterns of climate variability and aid in forecasting climate changes in the future. In this study, climate changes on the southeastern Tibetan Plateau over the past millennium were determined from a 4.82-m-long sediment core from Basomtso Lake. At the centennial time scale, the Medieval Climate Anomaly (MCA), Little Ice Age (LIA) and Current Warm Period (CWP) are distinct in the Basomtso region. Rapid climate fluctuations inferred from five episodes with higher sediment input and likely warmer conditions, as well as seven episodes with lower sediment input and likely colder conditions, were well preserved in our record. These episodes with higher and lower sediment input are characterized by abrupt climate changes and short time durations. Spectral analysis indicates that the climate variations at the centennial scale on the southeastern Tibetan Plateau are influenced by solar activity during the past millennium. PMID:27091591

  14. Rapid climate fluctuations over the past millennium: evidence from a lacustrine record of Basomtso Lake, southeastern Tibetan Plateau

    PubMed Central

    Li, Kai; Liu, Xingqi; Herzschuh, Ulrike; Wang, Yongbo

    2016-01-01

    Abrupt climate changes and fluctuations over short time scales are superimposed on long-term climate changes. Understanding rapid climate fluctuations at the decadal time scale over the past millennium will enhance our understanding of patterns of climate variability and aid in forecasting climate changes in the future. In this study, climate changes on the southeastern Tibetan Plateau over the past millennium were determined from a 4.82-m-long sediment core from Basomtso Lake. At the centennial time scale, the Medieval Climate Anomaly (MCA), Little Ice Age (LIA) and Current Warm Period (CWP) are distinct in the Basomtso region. Rapid climate fluctuations inferred from five episodes with higher sediment input and likely warmer conditions, as well as seven episodes with lower sediment input and likely colder conditions, were well preserved in our record. These episodes with higher and lower sediment input are characterized by abrupt climate changes and short time durations. Spectral analysis indicates that the climate variations at the centennial scale on the southeastern Tibetan Plateau are influenced by solar activity during the past millennium. PMID:27091591

  15. Recording of climate and diagenesis through sedimentary DNA and fossil pigments at Laguna Potrok Aike, Argentina

    NASA Astrophysics Data System (ADS)

    Vuillemin, Aurèle; Ariztegui, Daniel; Leavitt, Peter R.; Bunting, Lynda; The Pasado Science Team

    2016-04-01

    Aquatic sediments record past climatic conditions while providing a wide range of ecological niches for microorganisms. In theory, benthic microbial community composition should depend on environmental features and geochemical conditions of surrounding sediments, as well as ontogeny of the subsurface environment as sediment degraded. In principle, DNA in sediments should be composed of ancient and extant microbial elements persisting at different degrees of preservation, although to date few studies have quantified the relative influence of each factor in regulating final composition of total sedimentary DNA assemblage. Here geomicrobiological and phylogenetic analyses of a Patagonian maar lake were used to indicate that the different sedimentary microbial assemblages derive from specific lacustrine regimes during defined climatic periods. Two climatic intervals (Mid-Holocene, 5 ka BP; Last Glacial Maximum, 25 ka BP) whose sediments harbored active microbial populations were sampled for a comparative environmental study based on fossil pigments and 16S rRNA gene sequences. The genetic assemblage recovered from the Holocene record revealed a microbial community displaying metabolic complementarities that allowed prolonged degradation of organic matter to methane. The series of Archaea identified throughout the Holocene record indicated an age-related stratification of these populations brought on by environmental selection during early diagenesis. These characteristics were associated with sediments resulting from endorheic lake conditions and stable pelagic regime, high evaporative stress and concomitant high algal productivity. In contrast, sulphate-reducing bacteria and lithotrophic Archaea were predominant in sediments dated from the Last Glacial Maximum, in which pelagic clays alternated with fine volcanic material characteristic of a lake level highstand and freshwater conditions, but reduced water column productivity. Comparison of sedimentary DNA composition

  16. A compilation of Western European terrestrial records 60-8 ka BP: towards an understanding of latitudinal climatic gradients

    NASA Astrophysics Data System (ADS)

    Moreno, Ana; Svensson, Anders; Brooks, Stephen J.; Connor, Simon; Engels, Stefan; Fletcher, William; Genty, Dominique; Heiri, Oliver; Labuhn, Inga; Perşoiu, Aurel; Peyron, Odile; Sadori, Laura; Valero-Garcés, Blas; Wulf, Sabine; Zanchetta, Giovanni

    2014-12-01

    Terrestrial records of past climatic conditions, such as lake sediments and speleothems, provide data of great importance for understanding environmental changes. However, unlike marine and ice core records, terrestrial palaeodata are often not available in databases or in a format that is easily accessible to the non-specialist. As a consequence, many excellent terrestrial records are unknown to the broader palaeoclimate community and are not included in compilations, comparisons, or modelling exercises. Here we present a compilation of Western European terrestrial palaeo-records covering, entirely or partially, the 60-8-ka INTIMATE time period. The compilation contains 56 natural archives, including lake records, speleothems, ice cores, and terrestrial proxies in marine records. The compilation is limited to include records of high temporal resolution and/or records that provide climate proxies or quantitative reconstructions of environmental parameters, such as temperature or precipitation, and that are of relevance and interest to a broader community. We briefly review the different types of terrestrial archives, their respective proxies, their interpretation and their application for palaeoclimatic reconstructions. We also discuss the importance of independent chronologies and the issue of record synchronization. The aim of this exercise is to provide the wider palaeo-community with a consistent compilation of high-quality terrestrial records, to facilitate model-data comparisons, and to identify key areas of interest for future investigations. We use the compilation to investigate Western European latitudinal climate gradients during the deglacial period and, despite of poorly constrained chronologies for the older records, we summarize the main results obtained from NW and SW European terrestrial records before the LGM.

  17. Evaluation of annual resolution coral geochemical records as climate proxies in the Great Barrier Reef of Australia

    NASA Astrophysics Data System (ADS)

    Deng, Wenfeng; Wei, Gangjian; McCulloch, Malcolm; Xie, Luhua; Liu, Ying; Zeng, Ti

    2014-12-01

    Sampling of annually banded massive coral skeletons at annual (or higher) resolutions is increasingly being used to obtain replicate long-term time series of changing seawater conditions. However, few of these studies have compared and calibrated the lower annual resolution records based on coral geochemical tracers with the corresponding instrumental climate records, although some studies have inferred the climatic significance of annual coral series derived from averages of monthly or sub-annual records. Here, we present annual resolution analysis of coral records of elemental and stable isotopic composition that are approximately 70 years long. These records were preserved in two coexisting colonies of Porites sp. from Arlington Reef, on the Great Barrier Reef in Australia, and are used to evaluate the climatic significance of annually resolved coral geochemical proxies. The geochemical records of coral sample "10AR2," with its faster and relatively constant annual growth rate, appear to have been independent of skeletal growth rate and other vital effects. The annual resolution of Sr/Ca and Δδ18O time series was shown to be a good proxy for annual sea surface temperature (SST; r = -0.67, n = 73, p < 0.0000001) and rainfall records ( r = -0.34, n = 67, p < 0.01). However, a slower growing coral sample, "10AR1" showed significantly lower correlations ( r = -0.20, n = 71, p = 0.05 for Sr/Ca and SST; r = -0.19, n = 67, p = 0.06 for Δδ18O and rainfall), indicating its greater susceptibility to biological/metabolic effects. Our results suggest that while annually resolved coral records are potentially a valuable tool for determining, in particular, long timescale climate variability such as Pacific Decadal Oscillation, Interdecadal Pacific Oscillation, and other climatic factors, the selection of the coral sample is important, and replication is essential.

  18. A decadal gridded hyperspectral infrared record for climate Sep 1st 2002--Aug 31st 2012

    NASA Astrophysics Data System (ADS)

    Chapman, David Raymond

    We present a gridded Fundamental Decadal Data Record (FDDR) of Brightness Temperatures (BT) from the NASA Atmospheric Infrared Sounder (AIRS) from ten years of hyperspectral Infrared Radiances onboard the NASA EOS Aqua satellite. Although global surface temperature data records are available for over 130 years, it was not until 1978 when the Microwave Sounding Unit (MSU) was the first instrument series to reliably monitor long-term trends of the upper atmosphere. AIRS, operational on September 1, 2002 is the first successful hyperspectral satellite weather instrument of more than 1 year, and provides a 10 year global hyperspectral IR radiance data record. Our contribution was to prepare a gridded decadal data record of climate resolution from the AIRS Outgoing Longwave Spectrum (OLS). In order to do this, we developed a robust software infrastructure "Gridderama" using large multivariate array storage to facilitate this multi-terabyte parallel data processing task while ensuring integrity, tracking provenance, logging errors, and providing extensive visualization. All of our data, code, logs and visualizations are freely available online and browsable via a real-time "Data Catalog" interface. We show that these global all-sky trends are consistent with the expected radiative forcings from an increase in greenhouse gasses. We have also measured high global correlations with the GISS global surface air temperatures as well as high regional anticorrelations with the NOAA ONI index of El Niño phase. In addition, we have performed inter-annual inter-comparisons with the Moderate Resolution Spectro-radiometer (MODIS) on the same Aqua satellite to examine the relative consistency of their calibrations. The comparisons of the two instruments for the 4µ spectral channels (between 3.9µ and 4.1µ) indicate an inter-annual warming of 0.13K per decade of AIRS more than MODIS. This decadal relative drift is small compared to inter-annual variability but on the order of

  19. A mid-european decadal isotope-climate record from 15,500 to 5000 years B.P

    PubMed

    von Grafenstein U; Erlenkeuser; Brauer; Jouzel; Johnsen

    1999-06-01

    Oxygen-isotope ratios of precipitation (delta18OP) inferred from deep-lake ostracods from the Ammersee (southern Germany) provide a climate record with decadal resolution. The record in detail shows many of the rapid climate shifts seen in central Greenland ice cores between 15,000 and 5000 years before the present (B.P.). Negative excursions in the estimated delta18OP from both of these records likely reflect short weakenings of the thermohaline circulation caused by episodic discharges of continental freshwater into the North Atlantic. Deviating millennial-scale trends, however, indicate that climate gradients between Europe and Greenland changed systematically, reflecting a gradual rearrangement of North Atlantic circulation during deglaciation. PMID:10356392

  20. Lacustrine records of continental climate in northwest Greenland through the Holocene and Last Interglacial

    NASA Astrophysics Data System (ADS)

    McFarlin, J. M.; Axford, Y.; Osburn, M. R.; Lasher, G. E.; Francis, D. R.; Kelly, M. A.; Osterberg, E. C.

    2015-12-01

    Lake sediment records provide opportunities for high-resolution observations of paleoclimate that help to place modern climate change in geologic context. Here we present a terrestrial record of July air temperature for northwest Greenland (Nunatarssuaq, ~25 km east of the Thule Air Base) through the Holocene and a prior warm period, inferred from subfossil insect remains (Chironomidae) preserved in lacustrine sediments. In addition, we discuss ongoing work in characterizing the sources and isotopic composition of leaf waxes preserved in the same sediments. Multiple parallel sediment cores were collected in the summers of 2012 and 2014 from Wax Lips Lake (informal name), a non-glacial lake situated <2 km from the current margin of the Greenland Ice Sheet. Radiocarbon ages were obtained on aquatic mosses from intact laminae, and indicate that the record spans the Holocene, beginning at ~10.4 ka, as well as an interval beyond the range of 14C (>44 ka) and thus predates the Last Glacial Maximum (LGM). Our results demonstrate temperatures warmer than present through the early and mid Holocene followed by cooling in the late Holocene. Material that pre-dates the LGM contains insect assemblages indicating temperatures warmer than the warmest millennia of the Holocene. We interpret this material as most likely dating to the Last Interglacial Period (MIS 5). Along with assemblages of Chironomidae, we find subfossil Chaoboridae in one section of the pre-LGM sediments, suggesting exceptionally warm conditions based upon the distribution of modern-day Chaoborus. We find abundant n-alkanes and n-acids are preserved in the Holocene and pre-LGM sediments, allowing for complementary compound-specific δD analyses and identification of organic matter source in addition to chironomid derived temperature records.

  1. Grey Scale Record in Lake Baikal Sediments: Climate Significance for the Last 20 ka.

    NASA Astrophysics Data System (ADS)

    Fagel, N.; Boes, X.; Piotrovska, N.

    2004-12-01

    Three sediment cores from Lake Baïkal (52°N) are investigated to evidence Northern Eurasian regional climate and environmental changes. The last 20 ka are analyzed from Kasten cores (3-4 m) and short cores (60 cm) taken in turbidite free key-sites: Vydrino Shoulder, Posolsky Bank, and Continent Ridge (EU-CONTINENT project). The age-models of the cores are based on 14C AMS datings and magnetic susceptibility correlations. From the Late Glacial Maximum (LGM) to Present, sedimentation rates range around 0,05 to 0,14 mm/yr. Thus, the standard 5 mm sampling step represent a temporal resolution of no more than 100 to 30 years. The cores material was impregnated by a new polymer technique to analyze the sediments at higher resolution from continuous thin-section cover. We present continuous grey-scale record at 20 µm resolution, measured in the undisturbed part of the sediment, i.e. outside punctual burrows. The grey-scale is visually controlled by optical microscopy, and compared with magnetic susceptibility. Due to sediment properties, the grey-scale provides a high resolution record of diatom/clay ratio. For the Holocene, the grey density record shows that the biogenic productivity (diatoms) is related to the highest values (120-150 units), whereas the lowest values (80-100 units) are related to clays mixed with iron oxides and phosphates. The grey densities show an opposite trend compared to magnetic susceptibility. Our Baikal results are compared with Siberian chronozones and with global ice core record from Greenland (GISP 2).

  2. Combining Satellite and in Situ Data with Models to Support Climate Data Records in Ocean Biology

    NASA Technical Reports Server (NTRS)

    Gregg, Watson

    2011-01-01

    The satellite ocean color data record spans multiple decades and, like most long-term satellite observations of the Earth, comes from many sensors. Unfortunately, global and regional chlorophyll estimates from the overlapping missions show substantial biases, limiting their use in combination to construct consistent data records. SeaWiFS and MODIS-Aqua differed by 13% globally in overlapping time segments, 2003-2007. For perspective, the maximum change in annual means over the entire Sea WiFS mission era was about 3%, and this included an El NinoLa Nina transition. These discrepancies lead to different estimates of trends depending upon whether one uses SeaWiFS alone for the 1998-2007 (no significant change), or whether MODIS is substituted for the 2003-2007 period (18% decline, P less than 0.05). Understanding the effects of climate change on the global oceans is difficult if different satellite data sets cannot be brought into conformity. The differences arise from two causes: 1) different sensors see chlorophyll differently, and 2) different sensors see different chlorophyll. In the first case, differences in sensor band locations, bandwidths, sensitivity, and time of observation lead to different estimates of chlorophyll even from the same location and day. In the second, differences in orbit and sensitivities to aerosols lead to sampling differences. A new approach to ocean color using in situ data from the public archives forces different satellite data to agree to within interannual variability. The global difference between Sea WiFS and MODIS is 0.6% for 2003-2007 using this approach. It also produces a trend using the combination of SeaWiFS and MODIS that agrees with SeaWiFS alone for 1998-2007. This is a major step to reducing errors produced by the first cause, sensor-related discrepancies. For differences that arise from sampling, data assimilation is applied. The underlying geographically complete fields derived from a free-running model is unaffected

  3. RETRACTED: Impacts of past climate variability on marine ecosystems: Lessons from sediment records

    NASA Astrophysics Data System (ADS)

    Emeis, Kay-Christian; Finney, Bruce P.; Ganeshram, Raja; Gutiérrez, Dimitri; Poulsen, Bo; Struck, Ulrich

    2010-02-01

    This article has been retracted at the request of the Editor-in-Chief and Author. Please see Elsevier Policy on Article Withdrawal ( http://www.elsevier.com/locate/withdrawalpolicy). Reason: Paragraph 3.3 of this article contains text (verbatim) that had already appeared in a book chapter "Variability from scales in marine sediments and other historical records" by David B. Field, Tim R. Baumgartner, Vicente Ferreira, Dimitri Gutierrez, Hector Lozano-Montes, Renato Salvatteci and Andy Soutar. The book is entitled "Climate Change and Small Pelagic Fish", 2009, edited by Dave Checkley, Claude Roy, Jurgen Alheit, and Yoshioki Oozeki (Cambridge University Press; 2009).The authors would like to apologize for this administrative error on their part.

  4. A Fundamental Climate Data Record of Intercalibrated Brightness Temperature Data from SSM/I and SSMIS

    NASA Astrophysics Data System (ADS)

    Sapiano, M. R. P.; Berg, W. K.; McKague, D.; Kummerow, C. D.

    2012-04-01

    The first Special Sensor Microwave/Imager (SSM/I) was launched in June 1987 on the Defense Meteorological Satellite Program's (DMSP) F08 spacecraft and started what is now a nearly continuous 24-year record of passive microwave imager data that can be used to monitor the climate system. This includes such fields as precipitation (over both land and ocean), the extent of sea ice and snow, sea ice concentration, total precipitable water, cloud liquid water, and surface wind speed over oceans. A total of nine window channel radiometers have been launched to date in the DMSP series including the SSM/I instrument on board F08, F10, F11, F13, F14, and F15 followed by the Special Sensor Microwave Imager/Sounder (SSMIS) on board F16, F17, and F18, which is expected to operate for at least the next decade. As a result, this data record provides the best available source of long-term global observations of several hydrological variables for climate applications. Although the DMSP sensors provide a long-term record, because the sensors were developed for operational use there are a number of issues that must be addressed to produce a dataset suitable for use in climate applications. There are a several quality control and calibration issues including, but not limited to, quality control of the original antenna temperatures, geolocation, cross-track bias corrections, solar and lunar intrusion issues and emissive antennas. The goal of producing an FCDR of brightness temperature data involves not only addressing many of these instrument issues, but also developing a well-documented, transparent approach that allows for subsequent improvements as well as a framework for incorporating future sensors. Once the data have been quality controlled and various calibration corrections have been applied, the goal is to adjust the calibration of the various sensors so that they are physically consistent. Such intercalibration does not correct for changes due to local observing time, which

  5. A climatic record from 14C-dated wood fragments from southwestern Colorado

    USGS Publications Warehouse

    Epstein, S.; Xu, X.; Carrara, P.

    1999-01-01

    Deuterium concentrations in trees are related to the climatic temperature at which the trees grew. Deuterium analyses were made on all available (39) 14C-dated (all 14C dates cited are uncorrected) wood fragments collected from Lake Emma sediments. The 14C dates range from 9600 to 5400 'B.P.'. Tree line was above Lake Emma at 9600 'B.P.', was at Lake Emma at about 5000 'B.P.', and is 80 m below Lake Emma at the present time. The isotopic records at the various intervals of time coincide very well with this history. The range of ??D values is maximum at 9600 'B.P.' and is minimum at about 5400 'B.P.'. These data allow us to estimate the temperature range for the area between tree line and Lake Emma between these times. These results confirm previously observed cooling trends from several sources in the Western Hemisphere.

  6. Quality assessment and improvement of the EUMETSAT Meteosat Surface Albedo Climate Data Record

    NASA Astrophysics Data System (ADS)

    Lattanzio, A.; Fell, F.; Bennartz, R.; Trigo, I. F.; Schulz, J.

    2015-10-01

    Surface albedo has been identified as an important parameter for understanding and quantifying the Earth's radiation budget. EUMETSAT generated the Meteosat Surface Albedo (MSA) Climate Data Record (CDR) currently comprising up to 24 years (1982-2006) of continuous surface albedo coverage for large areas of the Earth. This CDR has been created within the Sustained, Coordinated Processing of Environmental Satellite Data for Climate Monitoring (SCOPE-CM) framework. The long-term consistency of the MSA CDR is high and meets the Global Climate Observing System (GCOS) stability requirements for desert reference sites. The limitation in quality due to non-removed clouds by the embedded cloud screening procedure is the most relevant weakness in the retrieval process. A twofold strategy is applied to efficiently improve the cloud detection and removal. The first step consists of the application of a robust and reliable cloud mask, taking advantage of the information contained in the measurements of the infrared and visible bands. Due to the limited information available from old radiometers, some clouds can still remain undetected. A second step relies on a post-processing analysis of the albedo seasonal variation together with the usage of a background albedo map in order to detect and screen out such outliers. The usage of a reliable cloud mask has a double effect. It enhances the number of high-quality retrievals for tropical forest areas sensed under low view angles and removes the most frequently unrealistic retrievals on similar surfaces sensed under high view angles. As expected, the usage of a cloud mask has a negligible impact on desert areas where clear conditions dominate. The exploitation of the albedo seasonal variation for cloud removal has good potentialities but it needs to be carefully addressed. Nevertheless it is shown that the inclusion of cloud masking and removal strategy is a key point for the generation of the next MSA CDR release.

  7. Quality assessment and improvement of the EUMETSAT Meteosat Surface Albedo Climate Data Record

    NASA Astrophysics Data System (ADS)

    Lattanzio, A.; Fell, F.; Bennartz, R.; Trigo, I. F.; Schulz, J.

    2015-07-01

    Surface albedo has been identified as an important parameter for understanding and quantifying the Earth's radiation budget. EUMETSAT generated the Meteosat Surface Albedo (MSA) Climate Data Record (CDR) currently comprising up to 24 years (1982-2006) of continuous surface albedo coverage for large areas of the Earth. This CDR has been created within the Sustained and Coordinated Processing of Environmental Satellite Data for Climate Monitoring (SCOPE-CM) framework. The long-term consistency of the MSA CDR is high and meets the Global Climate Observing System (GCOS) stability requirements for desert reference sites. The limitation in quality due to non removed clouds by the embedded cloud screening procedure is the most relevant weakness in the retrieval process. A twofold strategy is applied to efficiently improve the cloud detection and removal. A first step consists on the application of a robust and reliable cloud mask taking advantage of the information contained in the measurements of the infrared and visible bands. Due to the limited information available from old radiometers some clouds can still remain undetected. A second step relies on a post processing analysis of the albedo seasonal variation together with the usage of a background albedo map in order to detect and screen out such outliers. The usage of a reliable cloud mask has a double effect. It enhances the number of high quality retrievals for tropical forest areas sensed under low view angles and removes the most frequently unrealistic retrievals on similar surfaces sensed under high view angles. As expected, the usage of a cloud mask has a negligible impact on desert areas where clear conditions dominate. The exploitation of the albedo seasonal variation for cloud removal has good potentialities but it needs to be carefully addressed. Nevertheless it is shown that the inclusion of cloud masking and removal strategy is a key point for the generation of the next MSA CDR Release.

  8. Impact of Holocene climate variability on lacustrine records and human settlements in South Greenland

    NASA Astrophysics Data System (ADS)

    Guillemot, T.; Bichet, V.; Simonneau, A.; Rius, D.; Massa, C.; Gauthier, E.; Richard, H.; Magny, M.

    2015-11-01

    Due to its sensitivity to climate changes, south Greenland is a particularly suitable area to study past global climate changes and their influence on locale Human settlements. A paleohydrological investigation was therefore carried out on two river-fed lakes: Lake Qallimiut and Little Kangerluluup, both located close to the Labrador Sea in the historic farming center of Greenland. Two sediment cores (QAL-2011 and LKG-2011), spanning the last four millennia, were retrieved and showed similar thin laminae, described by high magnetic susceptibility and density, high titanium and TOC / TN atomic ratio, and coarse grain size. They are also characterized either by inverse grading followed by normal grading or by normal grading only and a prevalence of red amorphous particles and lignocellulosic fragments, typical of flood deposits. Flood events showed similar trend in both records: they mainly occurred during cooler and wetter periods characterized by weaker Greenlandic paleo-temperatures, substantial glacier advances, and a high precipitation on the Greenlandic Ice Sheet and North Atlantic ice-rafting events. They can therefore be interpreted as a result of ice and snow-melting episodes. They occurred especially during rapid climate changes (RCC) such as the Middle to Late Holocene transition around 2250 BC, the Sub-boreal/Sub-atlantic transition around 700 BC and the Little Ice Age (LIA) between AD 1300 and AD 1900, separated by cycles of 1500 years and driven by solar forcing. These global RCC revealed by QAL-2011 and LKG-2011 flood events may have influenced Human settlements in south Greenland, especially the paleo-Eskimo cultures and the Norse settlement, and have been mainly responsible for their demise.

  9. Climate, productivity, and intermediate water nutrients: new records from bamboo coral Ba/Ca

    NASA Astrophysics Data System (ADS)

    Lavigne, M.; Hill, T. M.; Spero, H. J.; Guilderson, T. P.

    2010-12-01

    A geochemical nutrient proxy from deep-sea corals would provide decadal to centennial scale records of intermediate-water nutrient dynamics. Such records could be used to determine how intermediate water masses (300-2000m) are affected by decadal scale climate change (e.g. Pacific Decadal Oscillation) via carbon cycling, export production, and intermediate water-mass circulation/ventilation. Because seawater barium (BaSW ) has a nutrient-like distribution in the water-column (similar to silicate), Ba/Ca records have been used to trace upwelled nutrient supply in shallow water surface corals isolated from terrestrial barium sources. Here we show the first calibration of a nutrient proxy from skeletal barium preserved in the calcitic internodes of bamboo corals. Our calibration was calculated from a depth transect (500-2000m) of Isidella and Keratoisis corals spanning a silicate and (BaSW ) gradient on the California Margin (Ba/Ca coral (µmol/mol) = 0.117 BaSW (nmol/kg ) + 0.835; R2 = 0.88; n = 29). The strong linear correlation between Ba/Ca coral and BaSW suggests that coral Ba/Ca is a reliable recorder of seawater barium (and, therefore, silicate). We find a distribution coefficient (DBa) for bamboo coral Ba/Ca of 1.3±0.1, similar to that of other corals (surface and deep-sea dwelling) and inorganic calcium carbonate precipitation experiments (DBa = 1.2-1.5). This implies that, as true for other carbonates, Ba incorporation is primarily driven by ionic substitution and holds promise as a globally applicable nutrient proxy in bamboo corals. High-resolution Ba/Ca timeseries records sampled via LA-ICP-MS in two co-located California Margin corals (Pioneer Seamount; 830m; 37°22’27”N) co-vary with ~decadal-scale variations in silicate and nitrate measured at 500m depth (CalCOFI line 80 sta. 60; 34°8’60”N). This suggests that high-resolution records of bamboo coral Ba/Ca can be used to reconstruct broad changes in intermediate water nutrients driven by

  10. Multitemporal Snow Cover Mapping in Mountainous Terrain for Landsat Climate Data Record Development

    NASA Technical Reports Server (NTRS)

    Crawford, Christopher J.; Manson, Steven M.; Bauer, Marvin E.; Hall, Dorothy K.

    2013-01-01

    A multitemporal method to map snow cover in mountainous terrain is proposed to guide Landsat climate data record (CDR) development. The Landsat image archive including MSS, TM, and ETM+ imagery was used to construct a prototype Landsat snow cover CDR for the interior northwestern United States. Landsat snow cover CDRs are designed to capture snow-covered area (SCA) variability at discrete bi-monthly intervals that correspond to ground-based snow telemetry (SNOTEL) snow-water-equivalent (SWE) measurements. The June 1 bi-monthly interval was selected for initial CDR development, and was based on peak snowmelt timing for this mountainous region. Fifty-four Landsat images from 1975 to 2011 were preprocessed that included image registration, top-of-the-atmosphere (TOA) reflectance conversion, cloud and shadow masking, and topographic normalization. Snow covered pixels were retrieved using the normalized difference snow index (NDSI) and unsupervised classification, and pixels having greater (less) than 50% snow cover were classified presence (absence). A normalized SCA equation was derived to independently estimate SCA given missing image coverage and cloud-shadow contamination. Relative frequency maps of missing pixels were assembled to assess whether systematic biases were embedded within this Landsat CDR. Our results suggest that it is possible to confidently estimate historical bi-monthly SCA from partially cloudy Landsat images. This multitemporal method is intended to guide Landsat CDR development for freshwaterscarce regions of the western US to monitor climate-driven changes in mountain snowpack extent.