HR: 0800h
AN: PP31A-1513    [Abstracts]
TI: Spatial manifestation of the Little Ice Age in Alaska
AU: * Clegg, B F
EM: bclegg@life.uiuc.edu
AF: University of Illinois, 505 S. Goodwin Ave. 265 Morrill Hall, Urbana, IL 61801 United States
AU: Tinner, W
EM: Willy.Tinner@ips.unibe.ch
AF: Institut fuer Pflanzenwissenschaften Universitaet Bern, Altenbergrain 21 , Bern, 3013 Switzerland
AU: Henderson, A
EM: ahenders@life.uiuc.edu
AF: University of Illinois, 505 S. Goodwin Ave. 265 Morrill Hall, Urbana, IL 61801 United States
AU: Bigler, C
EM: christian.bigler@emg.umu.se
AF: Umea University, Dept. of Ecology and Environmental Science KBC, Umea, SE - 901 8 Sweden
AU: Hu, F
EM: fshu@life.uiuc.edu
AF: University of Illinois, 505 S. Goodwin Ave. 265 Morrill Hall, Urbana, IL 61801 United States
AB: We present here climate reconstructions of the past 1000 years on the basis of multiproxy sediment analyses at six lakes in three regions of Alaska: the northwestern Alaskan Range (Farewell Lake), the southern Brooks Range (Takahula, Malamute, and Omega Lakes), and the Copper River Basin in southeastern Alaska (Grizzly and Moose Lakes). All three regions show a consistent decline in summer temperature of roughly 1.5 to 2 degrees C during Little Ice Age (LIA, 1480 - 1850 AD), in good agreement with previous estimates. However, effective-moisture reconstructions vary greatly among these regions. Oxygen isotopes, carbonate trace elements, and chironomid assemblages suggest that the SW and N portions of the Alaskan interior experienced a considerable effective-moisture increase and elevated lake levels during the LIA. At Takahula Lake, oxygen isotope analysis reveals that the rise in effective moisture occurred predominantly as a result of increased winter precipitation. In contrast, diatom-inferred water depths at Grizzly Lake dropped dramatically during the LIA, suggesting that the Copper River Basin became drier. The heterogeneity of the LIA moisture changes across our sites is consistent with the expected spatial pattern based on recent reconstructions of the position of the Aleutian Low (AL) during the LIA. Thus, variation of the strength/position of the AL appears to have been a major driver of the Alaskan climate over the last millennium.
DE: 0473 Paleoclimatology and paleoceanography (3344, 4900)
DE: 1605 Abrupt/rapid climate change (4901, 8408)
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 1637 Regional climate change
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005