Most Alaskan Glaciers Retreating, Thinning, and Stagnating

Oct 06, 2008

This August 1941 photograph is of Muir Glacier in Glacier Bay National Monument, Alaska. It shows the lower reaches of Muir Glacier, then a large, tidewater calving valley glacier and its tributary, Riggs Glacier. For nearly two centuries before 1941, Muir Glacier had been retreating. In places, a thickness of more than two-thirds of a mile of ice had been lost.

This August 1950 photo documents the significant changes that occurred during the 9 years between photographs A and B. Muir Glacier has retreated more than 2 miles, exposing Muir Inlet, and thinned 340 feet or more. However, it still is connected with tributary Riggs Glacier.

Photo courtesy of the National Snow and Ice Data Center and Glacier Bay National Park and Preserve Archive

This ship-deck-based August 1980 photograph of Muir Glacier and Muir Inlet, Glacier Bay National Park and Preserve, St. Elias Mountains, Alaska, shows the nearly 200-ft-high retreating tidewater end of Muir Glacier with part of its face capped by a few angular pinnacles of ice, called séracs. Note the icebergs in the ship's wake in the lower right side of the photograph. The location of Muir's terminus is less than a mile from the landward end of Muir Inlet.

Photo courtesy of Bruce Molnia, USGS).

This photo was taken in September 2003; in the 23 years between photographs, Muir Glacier has retreated more than a mile and ceased to have a tidewater terminus. Since 1980, Muir Glacier has thinned by more than 600 ft, permitting a view of a mountain with a summit elevation of greater than 4000 ft, located in the center of the photograph. A reexamination of the 1980 photograph shows that the summit of this mountain was visible but that it blended in with adjacent clouds.

Photo courtesy of Bruce Molnia, USGS).

This August 2004 photo further documents the significant changes that have occurred during the 63 years between photographs A and C, and during the 54 years between photographs B and C. Muir Glacier has retreated out of the field of view and is now nearly 5 miles to the northwest. Riggs Glacier has retreated as much as 2000 ft and thinned by more than 800 feet. Note the dense vegetation that has developed. Also note the correlation between Muir Glacier's 1941 thickness and the nearly horizontal line on the mountainside on the left side of the 2004 photograph. This line that indicates the past height of the glacier is called a trimline.

Photo courtesy of Bruce Molnia, USGS).