NOAA/WDS Paleoclimatology - Kongressvatnet, Svalbard, 1800 Year Lake Sediment Alkenone Paleotemperature

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) UK37 Period of sedimentation (yrs A.D.) JJA Temp (°C)* -0.654 2006-2009 5.8 -0.674 2003-2005 5.7 -0.649 1998-2002 5.3 -0.668 1992-1997 4.5 -0.693 1989-1991 4.6 -0.680 1985-1988 4.7 -0.706 1980-1984 3.9 -0.682 1972-1979 4.4 -0.695 1963-1971 3.9 -0.700 1956-1962 4.3 -0.691 1949-1955 4.3 -0.699 1944-1948 3.9 -0.721 1936-1943 4.2 -0.709 1927-1935 4.5 -0.687 1915-1926 4.4 "*Mean June/July/August Air temperatures over period of sedimentation (from Nordli, 2010)"
ABSTRACT SUPPLIED BY ORIGINATOR: 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.