A report on long-term glacier measurements released today by Secretary of the Interior Ken Salazar shows that glaciers are dramatically changing in mass, length and thickness as a result of climate change.

Over the past 50 years, U.S. Geological Survey (USGS) scientists have monitored the melting of Alaska’s Gulkana and Wolverine Glaciers and Washington’s South Cascade Glacier, yielding the longest such records in North America.

“This report we are releasing today is great example of the science and data our Department has gathered over the past 50 years,” said Secretary Salazar.  “This information is helpful in tackling the effects of climate change and it is exactly the kind of science we need to invest in to measure and mitigate the dangerous impacts of climate change.”

Glacier shrinkage has global impacts, including sea level rise that threatens low-lying and coastal communities. Smaller glaciers will also result in a decrease of water runoff, and impacts are especially important during the dry late summer when other water sources are limited.

“There is no doubt that most mountain glaciers are shrinking worldwide in response to a warming climate. Measuring changes in glacier mass provides direct insight to the link between glaciers and climate, ultimately helping predict glacier response to anticipated climate conditions,” said USGS scientist Edward Josberger.

The three glaciers monitored in this study are known as benchmark glaciers. They are widely spaced, represent different climate regimes, and can be used to understand the thousands of other glaciers in nearby regions.

USGS scientists study glacier behavior during different seasons, including summer melt and winter snow accumulation, as well as their response to both short and long term climate variations. This allows for more detailed insight regarding how and when the climate is changing.

“In addition to these three glaciers, more than 99 percent of America’s thousands of large glaciers have long documented records of an overall shrinkage as climate warms,” said USGS scientist Bruce Molnia. “Many people are surprised to learn that a few glaciers are thickening and advancing. These glaciers are responding to unusual and unique local conditions, including having large, high elevation areas where snow accumulates. Except for these anomalous few , most of America’s glaciers are shrinking and these exceptions emphasize how natural variability is an inherent part of a complex Earth system.”

You can view a video of South Cascade Glacier aerial photos from 1928 to 2006 at the USGS Washington Water Science Center Web site.

For more information on this study of glacier change in Washington and Alaska, visit Fact Sheet 2009-3046, Fifty-Year Record of Glacier Change Reveals Shifting Climate in the Pacific Northwest and Alaska, USA.

More information about the USGS Benchmark Glacier Program can be found online.