In 1980, the Columbia Glacier in Prince William Sound extended all the way to Heather Island.
Since then, the glacier's snout, or terminus, has retreated more than 12 miles, exposing prominent rings of brown bedrock. The mountain glacier has also lost about half of its total thickness and volume, according to NASA.
The following images track the glaciers rapid retreat over the last two decades. They were captured by NASA's Landsat satellites using infrared scans. Snow and ice appear bright blue, vegetation is green, open ocean is dark blue and open rock is brown.
