In a finding he calls "dramatic," Dr. Rick Wessels from the United States Geologic Survey (USGS) presented research that compared new satellite data with historical records and photographs of glaciers on mountains worldwide, showing that the majority of glaciers have decreased in size.

Wessels is part of the Global Land Ice Measurement from Space (GLIMS) project at USGS, which is using NASA's Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) to monitor mountain glaciers around the world. ASTER is one of the instruments on the TERRA satellite, launched in December 1999.

Using ASTER data from the last year and comparing it to historical glacier data, Wessels says his team was able to get preliminary results that show significant reduction in glacier size over the past decade.

For example, Wessels showed images of glaciers in the Andes Mountains in South America, which have decreased by almost a kilometer in the past 13 years, and a glacier in Columbia that the team is watching closely because it is losing meters of ice every week.

Wessels says the team has also seen glaciers shrinking in the Pyrenees in France and Spain as well as in the Swiss Alps.

He declares that the scientists can't tell why the glaciers are receding, but that mountain glaciers respond much more quickly than polar glaciers to changes in temperature and climate. (Wessels added that a few glaciers did actually increase in size, primarily those in mountains in Scandinavia.)

Wessels and his colleagues are also using the high resolution images from ASTER to look at crevasses and small bodies of water on the surface of glaciers -- giving scientists a better picture of the overall "health" of a particular glacial region.

The GLIMS team is focusing on the size and temperature of glacial lakes in the Tibetan Himalayas, including the Khumbu glacier on Mt. Everest that makes up part of the most popular route that climbers use when attempting to reach the world's highest peak.

Wessels says that eventually they will be able to monitor the status of every glacier in the world, and will be able to create a long-term assessment of glacier hazards.

(Editor's Note: This story is based on a release from Inside Science News Service, a product of the American Institute of Physics.)

Related websites:

American Geophysical Union Spring Meeting

GLIMS

ASTER

Images from ASTER

[Contact: Rory McGee]

31-May-2001