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Satellites track the West’s fading mountain glaciers

Mount Rainier glaciers
This map shows the elevation change of Mount Rainier glaciers between 1970 and 2016. The earlier observations are from USGS maps, while the recent data use the satellite stereo imaging technique. Glacier surface elevations have dropped more than 40 meters (130 feet) in some places. (University of Washington Photo / David Shean)

Elevation readings captured by satellites confirm that glaciers in the western United States are fading away at a worrisome rate.

The fade-out isn’t a surprise, considering the rise in global mean temperatures that’s ascribed to climate change. The new twist has to do with how the measurements were made.

University of Washington researcher David Shean looked back at satellite readings that have been amassed in databases, plus fresh readings that are being taken by DigitalGlobe’s constellation of GeoEye and WorldView satellites.

An analysis of the data, facilitated with NASA’s Ames Stereo Pipeline software, produces a 3-D elevation model of mountainous terrain. The method supplements other techniques to estimate glacier size, including area measurements based on aerial imagery and depth measurements made using stakes in the snow.

The result is a year-by-year record tracing the ups and downs of a glacier.

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By Alan Boyle

Mastermind of Cosmic Log, contributing editor at GeekWire, author of "The Case for Pluto: How a Little Planet Made a Big Difference," president of the Council for the Advancement of Science Writing. Check out "About Alan Boyle" for more fun facts.

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