NOAA/WDS Paleoclimatology - Lake GTH90, Northern Arctic Foothills, Alaska: Geochemical and Isotope Measurements Spanning the Past 3500 Years

Amplified warming in the Arctic has resulted in reduced sea-ice extent, which can impact regional climate dynamics. Elucidating temperature and moisture variability in the past in response to changing temperatures and sea-ice conditions can offer insight into how anthropogenic climate change may impact Arctic areas such as the Alaskan North Slope in the future. We contribute a new high-resolution record of integrated air temperature and precipitation variability from Lake GTH90 located on the Alaskan North Slope. This new record is based on the isotopic composition of chitin from lake sediments, and adds to a growing suite of Late Holocene climate records in northern Alaska. An overall decrease in d18O values from 3.5 ka to present at Lake GTH90 captures Neoglacial cooling associated with millennial-scale decrease in summer insolation. The highest and most variable d18O values occur between 3.5 and 2.6 ka and the lowest values are centered around 0.5 ka, suggesting that this record captures Little Ice Age cooling of up to 2°C. However, our record shows that on centennial timescales, climatic variables beyond air temperature likely contributed to the variability of d18O values at Lake GTH90. Variability in our record is consistent with temporal variability in sea-ice extent in the Arctic Ocean in the late Holocene, suggesting that periods of high sea-ice extent inhibited Arctic moisture sources and long-distance moisture transport from the North Pacific became dominant. In addition, shifts in the strength and position of the Aleutian Low contributed to the changes in the seasonality of precipitation in this region.