Figure A geographic information system representation of glacier shrinkage from 1850 to 1993 in Glacier National Park. The Blackfeet­Jackson glaciers are in the center. The yellow areas reflect the current area of each glacier; other colors represent the extent of the glaciers at various times in the past. (Courtesy: C. Key, USGS and R. Menicke, National Park Service) (Source: USGS - Understanding Climate Change Effects on Glacier National Park's Natural Resources)