NOAA/WDS Paleoclimatology - Little Swift Lake, Alaska 12KYr Multiproxy Sediment Data

STUDY NOTES: Multiproxy sediment data covering the last 12,000 years from Little Swift Lake, southwest Alaska. Data include major-element geochemistry, grain size measurements, loss on ignition, magnetic susceptibility, and pollen counts. Core LS-A, a 575-cm-long sediment core, was recovered from Little Swift Lake in 14.7 m of water in summer 1998. The lake is 24 m deep and has 0.7 km2 surface area.
ABSTRACT SUPPLIED BY ORIGINATOR: Multiproxy data from Little Swift Lake, an alpine lake in southwestern Alaska, provide evidence for pronounced late glacial and Holocene environmental change. An alpine glacier upvalley of Little Swift Lake retreated following the Younger Dryas chronozone, as evidenced by sedimentological changes in the lake record. Glacier retreat was accompanied by local and regional vegetation changes, including the expansion of Betula and contraction of Cyperaceae, in response to climatic amelioration. Warm, moist conditions between ~9800 and 8000 cal yr B.P. supported abundant Betula shrubs and high lake and watershed productivity. Alnus rapidly expanded near Little Swift Lake while the region cooled between 8000 and 7500 cal yr B.P. Environmental changes at Little Swift Lake appear to have been roughly synchronous with similar changes elsewhere in southwestern Alaska, but late glacial and Holocene changes in other parts of Alaska were different in nature and timing. The complex spatial and temporal patterns of late glacial and Holocene environmental change throughout Alaska point to the importance of local and regional-scale factors, especially controls on moisture availability, as modulators of site-specific responses to hemispheric- and global-scale climate forcing.