Glacier Change in the American West ANDREW G. FOUNTAIN, KRISTINA THORNEYCROFT, HASSAN J. BASAGIC, GREGORY J. McCABE Departments of Geology and Geography, Portland State University, Portland, , USA

Introduction Climate Glaciers are located throughout the American West in the states of Washington, Oregon, Principle component (PC) analysis was used to estimate annual glacier California, Montana, Wyoming, Colorado, Idaho, and Nevada. The glaciers occupy a area change based on seasonal temperatures and precipitation (Pwin, range of climates, are important indicators of climate trends in alpine regions, and play a Psum, Twin, Tsum) for 1900 through 2008. Two components emerged significant role in the hydrology of alpine ecosystems. (right). Stacked bar charts of the relative contributions of standardized Explained cumulative departures of seasonal precipitation and temperature to Variance We have compiled a 100-year history of glacier change using historic maps and PC1 55% departures of estimated glacier area change for each of PC sites (the PC2 31% photographs to identify the magnitude and rate of glacier change across the West. 1938 1981 1998 2006 relative contributions were computed using the regression for PC) 1960 USGS 2004 J. Scurlock Hileman, GNP Key,USGS Fagre, USGS Holzer, USGS shown below. South Cascade Glacier, Washington Grinnell Glacier, Montana PC1 PC2 Map-based 25%% wet Eliot Glacier, , Oregon 2 1158 Glacier Area 2.0 2.02 summers, 66% dry 31% wet winters, cool summers P wet cool winters Glacier Inventory 3079 46% 1.5 win 68.6 Lost since 1900 1.5 1.51.5 summers, summers, and cool winters 450 Tsum warm winters summers We inventoried all 24% 1.01 1.01 and summers glaciers, perennial ice, 0.50.5 0.50.5 Series3 0 Series2 0 and snow to define the 30% 0.0 0.0 Series2 Series1 Series1 463 208 -0.5 -0.5 number and area of these 1901 -0.5 -0.5 Psum 42.5 1475 features. The GIS 2.6 -1.0-1 -1.0-1 Twin wet summers, warm winters 73.3 mixed winters, T database is based on H.F. Reid 42% -1.5 warm summers -1.5 sum and summers -1.5 dry winters, cool summers -1.5 dry summers, USGS 7.5 minute (courtesy the warm summers 1 Mazamas) -2.0-2 -2.0-2 topographic quadrangle 190011920 211940 411960 611980 812000 101 190011920 214161811011940 1960 1980 2000 Contribution to Estimated Glacier Mass Balance 0.09 Contribution to Estimated Glacier Mass Balance maps (1:24,000 scale). 141 Year Year 4.8 40% periods with increases The USGS created these in glacier mass balance For PC1 sites, the recent negative effects of Glacier mass balance for PC2 sites are highly topographic maps from temperature on glacier mass balance appear periods with decreases in sensitive to temperature variability. glacier mass balance aerial photos. A total of to be unprecedented during the last century 2005 8303 glaciers, ice and 55% 1778 snow features were found 1913-1971 46.2 K.M. 5000 with a total area of 688 Jackson percent of area lost 4000 2 percent of area lost Elevation Differences km . currently being updated 3000 stratovolcano Glaciers that span large elevation differences (e.g. State totals Darwin Glacier, Sierra Nevada, California Glaciers 2000

glacier count in red on stratovolcanoes) are less sensitive to the (m) Elevation total area (km2) in grey US Forest Service lands effects of rising winter temperatures (rain vs 1000 fthh National Park Service lands snow), whereas those glaciers with a small 0 -10% 0% 10% 20% 30% 40% 50% 60% 70% 80% 90%

elevation range are more susceptible. This Area Change 1971-2002 highlights the role of local topographic effects. 5000

4000 Quantifying Glacier Change Andrews Glacier, Colorado Glacier 1908 3000 Glaciers of (right) Glacier boundaries were delineated from historic maps, ground and aerial photographs G.K. Gilbert 2000 into a GIS for a subset of glaciers in different regions in the American West. glaciers with area above 3000m (m) Elevation 1000 glaciers below 3000m 0 -10% 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% Mount Rainer (below) and winter temperatures (modeled PRISM data) Historic Maps Area Change

2004 Conclusions Climate H. Basagic 1916 W.T. Lee 2001 J. Achuff Overall warming is affecting all glaciers in the American West. Local Depending on altitude, warming winter temperatures may or may not Aerial Photos Meteorology play a role at this time. Differential shrinkage across the West appears to Surface Mass be controlled by variations in snow fall. Elevation range is an important And Glacier of the American West Website Energy Exchange factor in glacier response. GIS Glacier Our website contains more information including our Change Database Net Mass Change glacier inventory map, our photo archive with over Adios icy amigos. 14,000 historical and contemporary photographs, state and featured glacier articles, reports, and Repeat Photos References Dynamic glacier repeat photography. Response Basagic, H.J., and Fountain, A.G (submitted). Quantifying Twentieth Century Glacier Change in the Sierra Nevada. Fountain, A. G., Hoffman, M. J., Jackson, K. M., Basagic, H. J., Nylen, T., and Percy, D., 2007: Digital Outlines and Topography of the Changes Glaciers of the American West. U.S. Geological Survey Open-File Report 2006–1340, 23 pp.. In Check it out: www.glaciers.us Geometry Granshaw, F. D., and Fountain, A. G., 2006: Glacier change (1958-1998) in the National Park Complex, Washington, Effect on USA. Journal of Glaciology, 52: 251-256. Landscape (Meier, 1965) Hoffman, M. J., Fountain, A. G., and Achuff, J. M., 2007: Twentieth-century variations in area of small glaciers and icefields, Rocky Geologic Mountain National Park, Rocky Mountains, Colorado, USA. Annals of Glaciology, 46: 349-354. evidence Jackson, K. M., and Fountain, A. G., 2007: Spatial and morphological change on Eliot Glacier, Mount Hood, Oregon, USA. Annals of Glaciology, 46: 222-226. Meier, M. F., 1965: Glaciers and climate. In Wright, H. E., and Frey, D.G. (eds.) The Quaternary of the United States. Princeton: Princeton University Press, 795-805. (Top to bottom) Historic map of Lyell Glacier, CA (1885), aerial photo of Garnett Glacier, WY, repeat photos of Lyell Glacier, and moraines of Eliot Glacier, OR. Nylen, T., 2004: Spatial and Temporal Variations of Glaciers on Mount Rainier between 1913 and 1994. MS thesis. Portland State University, Portland, Oregon, 94 pp.