"Fifty years of U.S. Geological Survey (USGS) research on glacier change shows recent dramatic shrinkage of glaciers in three climatic regions of the United States. These long periods of record provide clues to the climate shifts that may be driving glacier change."
Beginning in 1957, the USGS has taken annual measurements of the South Cascade Glacier in Washington state, and followed shortly thereafter monitoring the Gulkana Glacier on the coast of Alaska and Wolverine Glacier in Alaska's interior.
All three glaciers have shrunk and thinned, the report says, with the mass loss rapidly accelerating over the past 15 years. The South Cascade Glacier has lost nearly 25% of its weight, and the two Alaskan glaciers about 15%.
Between 1987 and 2004 all three glaciers consistently lost more snow and ice each summer as compared to years prior, the report says. Combined with less snowfall the loss has led to the net decline of the glaceirs.
The study raises concerns about diminishing freshwater runoff and the future availability for fresh drinking water in areas that depend on the glaciers for water supply as they continue to shrink - some possibly disappearing entirely. The shrinkage also changes water temperatures, effecting the habitat of fish, insects, and other animals downstream, says USGS scientist Shad O'Neel.
Photo shows the South Cascade Glacier in 1928 (top) and now (bottom).