Tuesday, November 23, 2004
3:30 to 5:00
Our vanishing glaciers-A 100-year photographic record of glacier retreat in the central Oregon Cascade Range
Alpine glaciers respond sensitively to decadal scale changes in temperature and precipitation. Glaciers along the length of the Cascade Range have shrunk remarkably since their most advanced Little Ice Age positions of the early-to-mid 1800s. This has especially been the case in the Three Sisters Wilderness Area in central Oregon where 17 named glaciers covered 24 km2 during their maximum Little Ice Age advance but now cover less than 7.5 km2. The first recorded observations of Three Sisters glaciers were by USGS geologist Joseph S. Diller, who noted that the Three Sisters area "probably afford the most interesting field for glacial studies in the United States, with the exception of Alaska." Subsequent maps and photographs document substantial glacier shrinkage since then, which has been a topic of at least local interest since at least the 1930s. Glacier retreat in the Three Sisters mirrors trends worldwide and reflects regional warming of as much as 2 degrees (Celsius) since the late 19th century.
Jim O'Connor is a Research Hydrologist with the U.S. Geological Survey in Portland, Oregon.
University of Washington , B.S. Geological Sciences, 1982
University of Arizona , M.S. Geosciences, 1985
University of Arizona , Ph.D. Geosciences, 1990
1996-present: Research Hydrologist, U.S. Geological Survey, Portland, Oregon
1994-1996: Research Hydrologist, U.S.D.A. Forest Service Pacific Northwest Research Station, Portland, Oregon
1991-1994: National Research Council Post-Doctoral Fellow, U.S. Geological Survey, Cascades Volcano Observatory, Vancouver, Washington