A half-century worth of data on glacial advance and retreat released by the Interior Department clearly illustrates how climate change is affecting these rivers of ice in Alaska and Washington state.
Formally released Thursday by Interior Secretary Ken Salazar, the USGS study shows that glaciers are dramatically changing in mass, length and thickness as a result of climate change. The specific glaciers monitored by the USGS were Alaska’s Gulkana and Wolverine glaciers and Washington’s South Cascade Glacier. The study is the longest compiled on glaciers in North America, according to Interior officials.
“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 for the 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.”
For a look at how the South Cascade Glacier has receded down through the years, check out the video at this site: http://wa.water.usgs.gov/projects/glacier/video.html