MEASURING TWENTIETH CENTURY SURFACE AREA CHANGES AT SEVEN GLACIERS IN THE SIERRA NEVADA, CALIFORNIA

Alpine glaciers are important indicators of climate trends within a region and play a significant role in the hydrology of alpine ecosystems. The Sierra Nevada of California contains over 800 alpine glaciers and perennial ice features with an area greater than 0.01 km2. These glaciers provide an opportunity to determine regional responses to warming global temperatures over the past century. Here, we present a chronology of surface changes from seven glaciers located in and adjacent to Sequoia, Kings Canyon, and Yosemite National Parks. Past glacier extents of Lyell, Conness, Dana, Darwin, Goddard, Lilliput, and Picket Glaciers were complied in a Geographic Information System database. The surface extents are based on historical maps and photographs, as well as recent GPS mapping efforts. Preliminary results at the seven glaciers show a range between 30 and 70% loss in glacier area, with an average loss of 50% in area over the past century. The range in results suggests that topographic controls strongly influence individual glacier response to regional climate changes.