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Antarctic Peninsula Climate Variability: APRIL 3-5, 2002 |
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Ice Core Contributions to the Paleoclimate History of the Antarctic Peninsula Ellen Mosley-Thompson1,2 and Lonnie G. Thompson1,3 1Byrd Polar Research Center, Ohio State University, Columbus,
OH Ice cores collected on the Dyer Plateau of the Antarctic Peninsula (AP) in 1889-90 by a joint OSU-BAS project demonstrate the excellent preservation of seasonal variations in δO 18 and SO42- that allowed reconstruction of a very well dated 480-year record of climatic and environmental conditions in this region (Dai et al., 1995; Thompson et al., 1994). A complementary geophysical survey (Raymond et al., 1996) suggests that the ice flow pattern at this site, coupled with the high accumulation and relatively thin ice (265±8 meters), limits the likely length of a high resolution record from this site to several thousand years. However, their geophysical survey, including radio-echo sounding, confirmed that much longer records can be attained at nearby locations where the ice is much thicker. This region offers excellent potential for annually resolvable ice core proxy histories, but a thorough geophysical survey will be required to select optimal drilling sites. The highest priority for the ice core contribution to the AP paleoclimate history is to attain cores to bedrock from optimal sites in this region. Key questions to be addressed from the anticipated records include: (1) When did deglaciation begin in the region and how is it related to global climate change?; (2) How have the ice shelves changed over time?; (3) How are annual, decadal and century-scale climate variability in the AP related to climate variability on the same scales in the Pacific Basin (provided by multi-proxy histories from the PEP I transect)?; and (4) In light of the strong, unprecedented warming in the last 5 decades, are some of the proxy archives in the AP in imminent danger of being lost? The meteorological regime that brings precipitation to the AP Plateau is complex and likely dominated at different times by conditions to the east (the Weddell sea / South Atlantic sector) and to the west (the Amundsen Sea / South Pacific sector). Accurate interpretation of a long ice core history from AP plateau will require ancillary records from these meteorological regimes. Ideally an east-west transect of cores across the Peninsula should be attained; however, it must be determined which sites preserve an interpretable annual proxy record. In the last two decades a few other cores have been collected in the Peninsula region by BAS (e.g., Dolleman Island and Dronning Maude Land) and the European Union (EU) will begin drilling on Berkner Island in 2001. Once available, these records will complement the Antarctic Peninsula paleohistories by providing a larger-scale, regional context. A 550-year record from Siple Station at the base of the AP reveals similar trends in temperature (inferred from δ 18O) and accumulation on multi-decadal to century scales as the Dyer Plateau cores. Undoubtedly, excellent drill sites also exist southward on the AP (between Dyer and Siple Station) and should be considered as part of any comprehensive paleoclimate reconstruction. In addition, an ice core record from Plateau Remote (East Antarctica) appears to contain multi-decadal to century climate signals similar to those recorded at both Bermuda Rise and in the Lallemand Fjord. Recent discussions with BAS colleagues indicate their strong interest in collaborating with OSU to identify ideal drill sites and to drill and analyze the paleohistories contained therein. Dai, J., L.G. Thompson, and E. Mosley-Thompson. 1996. A
495-year record of atmospheric chloride, nitrate, and sulfate: Results
of chemical analysis of ice cores from Dyer Plateau, Antarctic Peninsula.
Annals of Glaciology, 21, 182-188. |
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