Three 'benchmark glaciers' rapidly retreating

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Known as "benchmark glaciers," the South Cascade Glacier in Washington state, along with the Wolverine Glacier on Alaska's Kenai Peninsula and the Gulkana Glacier in Interior Alaska, have all shown a "rapid and sustained" retreat, the report said.

For years scientists have reported glaciers around the world were melting, but the study, conducted by the U.S. Geological Survey, offers some of the most definitive findings to date. Because the three glaciers represent different climates and elevations, they can be used to understand thousands of other North American glaciers.