Shrinking glaciers. (Environment).

A great majority of the world's glaciers appear to be declining at rates equal to or greater than long-established trends. The retreat is significantly affecting agriculture, water supplies, hydroelectric power, transportation, mining, coastlines, and ecological habitats. The net loss or benefit

"It's not all doom and gloom," USGS scientist Jeff Kargel says. "Glaciers are wastelands, but as they recede the land underneath may become available for use."

Kargel and his team are comparing current glacier satellite images with topographical maps and other glacier records from the twentieth century. Not all glaciers are receding at the same rate, and a few glaciers are advancing. "Glaciers in the Himalayas are wasting at alarming and accelerating rates, as indicated by comparisons of satellite and historic data, and as shown by the widespread, rapid growth of lakes on the glacier surfaces," says Kargel.

For example, the Gangotri Glacier between Kashmir and Nepal is retreating at an accelerated rate that cannot be accounted for by lingering effects from warming after the Little Ice Age more than 200 years ago. Gangotri is one of many glaciers feeding the Ganges River Basin, upon which hundreds of millions of people, including those in New Delhi and Calcutta, depend for fresh water.

Glaciologists at the University of Alaska Fairbanks Geophysical Institute also note changes in Alaska's glaciers. "Most glaciers have thinned several hundred feet at low elevations in the last 40 years and about 60 feet at higher elevations," says the Institute's Keith Echelmeyer. He and his team have calculated that Alaska glaciers are responsible for at least 9% of the global sea-level rise during the past century, and Alaska's glaciers raise the level of Earth's oceans by more than 0.1 millimeter each year.

As Alaska's permafrost thaws, the consequences are dramatic and alarming. Sagging roads, crumbling villages, sinking pipelines, the proliferation of insects that are destroying spruce forests, and the possible disruption of marine wildlife are among the effects seen as the thaw continues. Some Alaskans talk about "drunken trees" that list and show their roots because of the rapid decline of the permafrost.

Sources: National Aeronautics and Space Administration, Goddard Space Flight Center, Greenbelt, Maryland 20771. Web site www.gsfc.nasa.gov.

University of Alaska Fairbanks Geophysical Institute, P.O. Box 757520, Fairbanks, Alaska 99775. Web site www.uaf.edu.