HR: 16:30h
AN: PP44A-03 INVITED    [Abstracts]
TI: Glacier Changes and Inferred Temperature Variability in Alaska for the Past Two Thousand Years
AU: * Wiles, G C
EM: gwiles@wooster.edu
AF: The College of Wooster, Department of Geology 1189 Beall Ave., Wooster, OH 44691, United States
AU: Barclay, D J
EM: barlcayd@cortland.edu
AF: SUNY Cortland, Geology Department, Cortland, NY 13045, United States
AU: Malcomb, N
EM: nmalcomb@wooster.edu
AF: The College of Wooster, Department of Geology 1189 Beall Ave., Wooster, OH 44691, United States
AB: Comparisons of temperature sensitive tree-ring records with histories from land-terminating, non-surging glaciers for the last two millennia from Alaska identify summer temperature as a primary driver of glacier changes. Uniform retreat of glaciers across Alaska attests to the sensitivity of this proxy to warming, whereas examination of the paleorecord places these contemporary changes into a longer-term perspective. Two major intervals in the Alaskan chronology of glaciation, during the First Millennium AD (FMA) and again during the Little Ice Age (LIA), are evident as broad times of cooling and ice expansion. These two intervals are respectively followed by ice retreat coincident with the Medieval Warm Period (MWP) and contemporary warming, and together correspond with millennial-scale variations recognized in other Alaskan proxy records. The FMA advance appears to be of similar extent as the subsequent LIA expansions indicating a uniformity of forcing over the past two millennia. This general millennial-scale history of temperature variability can be compared with the behavior of tidewater glacier margins over the same two thousand year interval. It is clear over this time that tidewater expansions were underway in the FMA, during the height of the MWP and persisted through the LIA. That some tidewater glaciers advanced during the MWP and retreated during portions of the LIA reflects the control of non-climatic factors on tidewater glacier fluctuations. Understanding these non-climatic factors and the fate of Alaskan glaciers is vital as their contribution to global sea level rise in the coming decades to centuries is of major importance, and as the economic and ecological impacts of deglaciated Alaskan mountain ranges becomes a reality.
DE: 0700 CRYOSPHERE (4540)
DE: 0720 Glaciers
DE: 1105 Quaternary geochronology
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 1620 Climate dynamics (0429, 3309)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting