A re-evaluation and spatial analysis of evidence for a Younger Dryas climatic reversal in Beringia |
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Authors: | H.D. Kokorowski P.M. Anderson C.J. Mock A.V. Lozhkin |
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Affiliation: | aDepartment of Earth and Space Sciences and the Quaternary Research Center, University of Washington, Box 351310, Seattle, WA 98195-1310, USA;bDepartment of Geography, University of South Carolina, Columbia, SC 29208, USA;cNortheast Interdisciplinary Science Research Institute, Far East Branch, Russian Academy of Sciences, 16 Portovaya Street, Magadan 685000, Russia |
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Abstract: | An objective classification of paleoclimatic proxies from 75 lake and peat records is used to re-evaluate data quality and inferred climatic patterns in Beringia during the Younger Dryas. Mapped data reveal coherent but spatially-complex regional patterns, suggesting the Younger Dryas was characterized by: (1) cooling in Southern Alaska, Eastern Siberia, and portions of Northeastern Siberia; and (2) uniform to warmer-than-present conditions through most of Central Alaska, Northeastern Siberia, and possibly the Russian Far East and Northern Alaska. The Beringian patterns correspond to distinctive large-scale climatic forcings, although in some locations further modified by more local influences, such as topography. General circulation models and modern synoptic climatology provide a conceptual framework for exploring possible mechanisms responsible for the observed changes. Forcings and associated climatic responses consistent with the proxy data include: (1) lowered sea-surface temperatures in the North Atlantic and Pacific reducing temperature and precipitation in Eastern Siberia; (2) intensified Aleutian low and lowered sea-surface temperatures causing cooler summers and higher winter precipitation in Southern Alaska; (3) stronger Pacific Subtropical High and an eastward shift of the East Asian Trough reducing summer temperatures in Southern Alaska and causing relative warmth in Northeastern Siberia; and (4) strong high pressure system producing warm, dry conditions in interior Alaska. |
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