Shrinking mountain glaciers

MOUNTAIN GLACIERS around the world are receding, said geophysicists at the annual spring meeting of the American Geophysical Union (AGU) in Boston. Dr. Rick Wessels from the United States Geologic Survey (USGS) presented his research results that compared new satellite data to historical records and photographs of glaciers on mountains worldwide, showing that majority of glaciers studied 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 glaciers around the world. ASTER is an instrument on the TERRA satellite. Using ASTER data from last year, and comparing it to historical glacier data, according to a report in the American Institute of Physics, 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, which the team is watching closely because it is losing meters of ice each week. Wessels says the team has also seen glaciers shrinking in the Pyrenees Mountains in France and Spain, as well as in the Swiss Alps.

Wessels says they cannot tell why the glaciers are receding, but does say that mountain glaciers respond much more quickly than polar glaciers to changes in temperature and climate. Wessels also added that a few glaciers studied did actually increase in size, although he said these were primarily limited to mountains in Scandinavia.

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

One of the areas where the GLIMS team is focusing research on the size and temperature of glacial lakes in the Tibetan Himalayas, including the Khumbu glacier on Mt. Everest - which 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.

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