Alaska glacier moving faster

The Columbia Glacier is currently about 34 miles in length, three miles wide and more than 3,000 feet thick in places.

June 21, 1999
Web posted at: 12:19 p.m. EDT (1619 GMT)

Alaska's Columbia Glacier has increased its speed from 82 feet per day to 115 feet per day in recent months and within the next few years it could fill Prince William Sound with icebergs, according to a University of Colorado glaciologist.

Already the world's fastest moving glacier, the glacier is suddenly flowing even faster down its channel. Because icebergs are breaking off the glacier faster than the rate of flow, the glacier is retreating and may soon retreat back to where its channel rises above sea level.

Since 1982, the Columbia Glacier has retreated about seven miles. It is currently about 34 miles in length, three miles wide and more than 3,000 feet thick in places. The end of the glacier, known as a tidewater glacier, rests in waters 300 to 600 feet deep.

If the glacier continues to retreat the end of the glacier will soon be resting in waters that are 2,000 feet deep. Glaciologists are not sure why, but icebergs tend to calve off of glaciers more frequently when the glacial end is in deeper water.

"The deeper the water, the faster they calve," said Tad Pfeffer, a researcher at the university's Institute of Arctic and Alpine Research.

The glacier is moving so fast because it is getting thinner and parts of it are floating on the water. "Once they lose contact with the bed, glaciers start moving faster," said Pfeffer.

Researchers are not sure why the glacier is getting thinner, but some scientists, including Mark Meier, a retired professor at the University of Colorado, point to global warming.

In general, however, Pfeffer said that tidewater glaciers are not a good indicator of climate change. "But the climate may have a long-term effect on these tidewater glaciers we don't yet understand. When a glacier thins to a critical level, it seems to be the point of no return."

Pfeffer will take stereoscopic photography images of the glacier from land adjacent to the glacier beginning late this month to further study its movement.

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