For more information

Website:

http://www.mesc.usgs.gov/glacier

Publications:

Fagre, D.B., 1998, Understanding climate change impacts on Glacier National Park's natural resources, in Mac, M.J., Opler, P.A., Puckett-Haecker, C.E., and Doran, P.D., eds., Status and trends of the Nation's biological resources: Washington, D.C., U.S. Department of the Interior, In press.

Key, C.H., Fagre, D.B., and Menicke, R.K., Glacier recession in Glacier National Park, Montana, in Williams, R.S., and Ferrigno, J.G., eds., Satellite image atlas of glaciers of the world, U.S. Geological Survey Professional Paper 1386-J, In press.

Melting Glaciers Signal Change in National Parks

National parks are being altered by global climate change. Though the impact is not always easy to detect, evidence for these changes is seen in the shrinking glaciers of Glacier National Park, Montana. As part of a comprehensive assessment of the park's ecosystem, USGS scientists are studying the glaciers' response to more than a century of warming.

Since 1850, larger glaciers in the park have been reduced to a third of their previous size and continue to shrink. Some have receded more than a mile into the shadows of steep cliffs. Many smaller glaciers have entirely disappeared. A computer model predicts that all glaciers in the park will be gone by 2030 if global temperatures continue to rise as forecast. Even with no additional rise in temperature, the park's glaciers will be largely gone by 2100.

Because glaciers respond to changes in temperature and precipitation, a long period of glacier shrinkage represents a shift in climate. Thus, glacial change provides an early indicator of fundamental climatic change, change that will

ultimately affect other parts of the ecosystem as well. The absence of glaciers will directly affect environmental variables such as stream flow and temperature in mountain watersheds, especially late in summer. But perhaps of greatest significance is that melting glaciers indicate broader changes to which plants and animals must adapt.

The USGS's 7-year modeling and monitoring effort provides a computer-based system to simulate how plants and animals might respond to not only climate change but also to resulting changes in fire intensity and frequency, plant invasions and redistribution, and other environmental variables. This tool provides explicit scenarios to help park managers, policy makers, and the public understand and make decisions about the future of national parks.

The results of this study paint a vivid picture, not only of the magnitude of a future problem, but of changes already apparent in national parks. By better understanding the response of glaciers and other ecosystem functions to global warming, the Nation can better prepare and manage for its consequences.

Boulder Glacier, Glacier National Park, Montana, July 1932 (left) and July 1988 (right), 56 years later, from the same point. The ice cave and glacier have completely disappeared.