Retreat of Alaska’s Columbia Glacier
The Columbia Glacier descends from an ice field 3,050 meters (10,000 feet) above sea level, down the flanks of the Chugach Mountains, and into a narrow inlet that leads into Prince William Sound in southeastern Alaska. It is one of the most rapidly changing glaciers in the world.
The Columbia is a large tidewater glacier, flowing directly into the sea. When British explorers first surveyed it in 1794, its nose—or terminus—extended south to the northern edge of Heather Island, a small island near the mouth of Columbia Bay. The glacier held that position until 1980, when it began a rapid retreat that continues today.
These two false-color images, both captured by the Thematic Mapper (TM) instrument on Landsat 5, show the glacier and the surrounding landscape in 1986 and 2011. Snow and ice appears bright cyan, vegetation is green, clouds are white or light orange, and the open ocean is dark blue. Exposed bedrock is brown, while rocky debris on the glacier’s surface is gray. The 2011 image has more snow because it was captured in May, while the 1986 image was captured in July.
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