CGRG Bibliography of Canadian Geomorphology
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Author : Elias, S.A.
Date : 1998
Title : Late Wisconsin climates in Eastern Beringia, based on fossil beetle evidence
Publication : AMQUA 1998 - American Quaternary Association Program and Abstracts of the 15th Biennial Meeting, Puerto Vellarta, Mexico, 5-7 September 1998.
Issue :
Page(s) : 90.
Abstract
Fossil beetle assemblages from sites in Alaska and the Yukon Territory are now yielding quantitative estimates of mean temperatures of the warmest (TMAX) and coldest months (TMIN) of the year. These estimates are derived from Mutual Climatic Range analyses of fossil assemblages. The estimates have been calibrated using linear regression formulas derived from modern tests of observed vs. MCR-predicted TMAX and TMIN at 25 regional sites. Mid-Wisconsin and late glacial climatic ameliorations are evident in the TMAX reconstructions for Eastern Beringia. At sites in the subarctic regions, a mid-Wisconsin interstadial appears to have peaked about 30,000 yr. B.P. The MCR estimates from subarctic assemblages indicate that TMAX values were within about 2ºC of modern levels at that time. At arctic sites, TMAX estimates from the Mid-Wisconsin interstadial indicate that TMAX values rose as much as 2ºC above modern levels. TMIN values during this interstadial were about 4ºC colder than modern in both arctic and subarctic assemblages. Fossil assemblages from the last glacial maximum yielded TMAX values about 3.5ºC colder than modern at subarctic sites, and about 5ºC colder than modern at arctic sites. TMIN values for all sites were only 1-2ºC colder than modern during the LGM. Late glacial warming is shown in both arctic and subarctic assemblages, beginning about 12,500 yr. B.P. By 11,000 yr. B.P., arctic assemblages indicate TMAX values as much as 5ºC warmer than modern, while subarctic assemblages indicate warming to about 2ºC above modern levels. Arctic assemblages show a dramatic cooling of summer temperatures between 10,900 and 10,000 yr. B.P., the first clear evidence of a climatic oscillation during the Younger Dryas chronozone in arctic Alaska and the Yukon Territory.
Bibliography of Canadian Geomorphology