Niki Bowerman

Alpine glaciers expand and retreat rapidly in response to changes in climate, particularly winter precipitation and summer temperature. With few exceptions, however, past changes in extent of glaciers in the western U.S. during the Holocene (last 10,000 years) are poorly constrained. I propose to develop the most comprehensive record yet obtained of Holocene glaciation in the Sierra Nevada, California, by combining detailed glaciologic mapping and reconstructions with intensive analyses of lake sediments associated with the largest glacier in the range, the Palisade Glacier. Sediments in the lakes will provide the longest and most detailed records of Holocene glacial fluctuations available in the Sierra Nevada. These records will constrain the responses of glaciers and alpine ecosystems to proposed periods of extreme drought (Stine, 1994) and cooling (Feng and Epstein, 1994) as well as test the timing of onset of Neoglaciation in the range (Konrad and Clark, 1998). On a broader scale, detailed comparisons to other equivalent glacial records across the American Cordillera will test the regional climate response to proposed Holocene climate perturbations (e.g., the 8200 yr. B.P. cold period in Greenland; Alley et al., 1997; 5.2 kyr. B.P. and 4.2 kyr B.P. cold events; Thompson, 2004).

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