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Documenting Twentieth Century Glacier Change with Repeat Photography in the Sierra Nevada, California HASSAN J BASAGIC; ANDREW G

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Documenting Twentieth Century Glacier Change with Repeat Photography in the Sierra Nevada, California HASSAN J BASAGIC; ANDREW G Documenting Twentieth Century Glacier Change with Repeat Photography in the Sierra Nevada, California HASSAN J BASAGIC; ANDREW G. FOUNTAIN Department of Geography, Portland State University, Portland, Oregon, 97207 Introduction Repeat Photography Quantifying Glacier Change Alpine glaciers are important indicators of climate trends within a region and play a We gathered historical photos from the USGS Earth Science Photographic Archive (http://libraryphoto.er.usgs.gov/) significant role in the hydrology of alpine ecosystems. The Sierra Nevada of California and re-photographed following methods outlined by Harrison (1960) and Klett et al. (1984). The data Change in glacier area was calculated for Lyell Glacier in Yosemite National Park for contains approximately 497 alpine glaciers and perennial ice features (Raub, 1980). serve as a visual comparison of change through time. Below are the results from four of the ten the three time periods of 1883, 1944, 2003. Early photographs and a map by I.C. These glaciers provide an opportunity to determine regional responses to warming locations. Russell indicate that the Lyell glacier extent was near or at the Matthes, or Little Ice global temperatures over the past century. Historical photos of glaciers taken by early Age maximum (Russell, 1885). The 1944 extent was delineated from aerial and explorers, land surveyors, and park rangers in the late 19th century and early 20th ground based photographs. The 2003 extent was collected in the field with GPS. century are valuable records of past conditions. Repeat photography of glaciers is a Dana Glacier useful way to determine how these Sierra Nevada glaciers and perennial ice features have changed through time. During the summer of 2003 and 2004, over 52 repeat images were collected from ten glaciers located throughout the Sierra Nevada. Kilometers 02.55 120°0'0"W 119°0'0"W 1883 map of Lyell Glacier (Russell, 1944 Army aerial photograph 1885) 1883 I.C. Russell September 5, 2004 H. Basagic Lyell Glacier Mapping terminus with GPS 00 3500 36 0 360 38°0'0"N 0 0 7 38°0'0"N 3 600 3700 3 Surface Area of Lyell Glacier 1883 - 2003 0.8 0.7 3 8 3 700 ) 00 0 2 0.6 Kilometers 38 0 0.5 38 02.55 00 0.4 39 00 0.3 + 00 39 PEAK 0.2 1883 Surface Area (km + 3927m MOUNT LYELLLYELL 1944 0.1 3998m Legend I.C. Russell H. Basagic 0.0 August 15, 2003 2003 1883 1850 1900 1950 2000 Glaciers and perennial ice $ Year Moraines and rock glaciers Met ers Elevation (m) 0 220 440 West Lobe East Lobe High : 4412 37°0'0"N Low : 672 $ 37°0'0"N 1:800,000 Conclusion Kilometers 0204010 Comparisons of the repeat photography reveal that all ten of the glaciers have experienced a reduction in ice volume and surface extent over the past century. August 7, 1903 G.K. Gilbert September 5, 2004 H. Basagic Repeat photography is a valuable tool in determining change through time, especially when combined with aerial photos and field measurements. The case example at Darwin Glacier Lyell Glacier indicate the surface area of the west lobe has been reduced by 30% since 1883, and the smaller east lobe has been reduced by 70%. These results suggest that topographic controls strongly influence individual glacier response to regional and global climate change. 120°0'0"W 119°0'0"W References Glacier regions of the Western United States Harrison, A.E., 1960. Exploring Glaciers-with a Camera. Sierra Club Books, San Francisco, CA, 71 pp. Klett, M., Manchester, E., Verburg, J., Bushaw, G. and Dingus, R., 1984. Second View: The Rephotographic Survey Project. Essay by Paul Berger. University of New Mexico Press, Albuquerque. August 14, 1908 G.K. Gilbert August 14, 2004 H. Basagic Sierra Nevada Glacier Inventory Raub, W.B., Post, A., Brown, C.S. and Meier, M.F., 1980. Perennial ice masses of the Sierra Nevada, California, Goddard Glacier World glacier inventory. IASH-AISH Publication 126: 33-34. We performed an inventory of all Sierra Nevada glaciers, perennial ice, and Russell, I.C., 1885. Existing Glaciers of the United States. 5th Annual Report of the U.S. Geologic Survey snowfields to understand the distribution and quantity of these features. The GIS U.S. Geological Survey, Earth Science Photographic Archive.Online at http://libraryphoto.er.usgs.gov database is based on USGS 7.5 minute topographic quadrangle maps (1:24,000 scale). The USGS created these topographic maps from aerial photos taken between Acknowledgements 1975 and 1984. A total of 1795 ice and snow features were found along with 454 Special thanks to Danny Boiano, Annie Esperanza, Pat Lineback, and DNR at Sequoia & Kings Canyon National moraines and rock glaciers. Parks; Nate Stephenson, BRD, USGS; and Hal Pranger, Geologic Resources Division, NPS. August 13, 1908G.K. Gilbert August 16, 2004 H. Basagic.
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