Kongressvatnet, Svalbard, 1800 Year Lake Sediment Alkenone Paleotemperature D'Andrea, W.J.; Vaillencourt, D.A.; Balascio, N.L.; Werner, A.; Roof, S.R.; Retelle, M.J.; Bradley, R.S. D'Andrea, W.J. Vaillencourt, D.A. Balascio, N.L. Werner, A. Roof, S.R. Retelle, M.J. Bradley, R.S. Air Temperature Reconstruction Arctic Little Ice Age (LIA) Medieval Climate Anomaly (MCA) earth science/paleoclimate/climate reconstructions|paleolimnology (surface temperature,alkenone unsaturation index,null,degree Celsius,Jun-Aug,climate reconstructions|paleolimnology,null,null,N,null) earth science/paleoclimate/climate reconstructions|paleolimnology (age,null,null,year Common Era,null,climate reconstructions|paleolimnology,null,null,N,null) earth science/paleoclimate/paleolimnology (alkenone unsaturation index Uk37,null,null,dimensionless,null,paleolimnology,null,null,N,null) earth science/paleoclimate/paleolimnology earth science/paleoclimate/paleolimnology (Kongressvatnet>LATITUDE 78.0217>LONGITUDE 13.9311) The Arctic region is subject to a great amplitude of climate variability and is currently undergoing large-scale changes due in part to anthropogenic global warming. Accurate projections of future change depend on anticipating the response of the Arctic climate system to forcing, and understanding how the response to human forcing will interact with natural climate variations. The Svalbard Archipelago occupies an important location for studying patterns and causes of Arctic climate variability; however, available paleoclimate records from Svalbard are of restricted use due to limitations of existing climate proxies. Here we present a sub-decadal- to multidecadal-scale record of summer temperature for the past 1800 yr from lake sediments of Kongressvatnet on West Spitsbergen, Svalbard, based on the first instrumental calibration of the alkenone paleothermometer. The age model for the High Arctic lake sediments is based on 210Pb, plutonium activity, and the first application of tephrochronology to lake sediments in this region. We find that the summer warmth of the past 50 yr recorded in both the instrumental and alkenone records was unmatched in West Spitsbergen in the course of the past 1800 yr, including during the Medieval Climate Anomaly, and that summers during the Little Ice Age (LIA) of the 18th and 19th centuries on Svalbard were not particularly cold, even though glaciers occupied their maximum Holocene extent. Our results suggest that increased wintertime precipitation, rather than cold temperatures, was responsible for LIA glaciations on Svalbard and that increased heat transport into the Arctic via the West Spitsbergen Current began ca. A.D. 1600. STUDY NOTES: 1800-year UK37 and inferred summer temperature reconstruction based on alkenone unsaturation in lake Kongressvatnet, western Svalbard Included data: UK37 measurements, inferred temperature, depth, age UK37 calibration data table Major oxides from all measured isolated tephra grains Age-depth model data (210Pb & 239+240Pu ages and tephra ages) NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : D'Andrea, W.J. Investigator : Vaillencourt, D.A. Investigator : Balascio, N.L. Investigator : Werner, A. Investigator : Roof, S.R. Investigator : Retelle, M.J. Investigator : Bradley, R.S. 2012-10-22 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/13458 https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/europe/norway/kongressvatnet2012.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/europe/norway/kongressvatnet2012.txt English https://www.ncdc.noaa.gov/paleo/study/13458 https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/europe/norway/kongressvatnet2012.txt D'Andrea, W.J., D.A. Vaillencourt, N.L. Balascio, A. Werner, S.R. Roof, M. Retelle, and R.S. Bradley. 2012. Mild Little Ice Age and unprecedented recent warmth in an 1800 year lake sediment record from Svalbard. Geology, November 2012, v. 40, p. 1007-1010. DOI: 10.1130/G33365.1 START YEAR: 250 AD * END YEAR: 2008 AD 13.9311 78.0217 13.9311 78.0217