06:54 AM PST on Monday, March 27, 2006

Associated Press

An Oregon landmark is changing before our eyes.

Photo by kgw.com contributor Randy Craig.

Mt. Hood

The seven largest of Mount Hood's 11 glaciers have shrunk by an average of more than 30 percent since the beginning of the last century, according to calculations by a Portland State University graduate student.

Keith Jackson, who is part of a glacier research team financed by the National Science Foundation and NASA, estimates that Sandy Glacier, on Mount Hood's west slopes facing Portland, covers about 60 percent less ground than it did a century ago and Eliot Glacier has lost at least half of its ice in the last 100 years.

And scientists think glaciers might recede faster in the coming century because of warmer temperatures. Average low temperatures at Eliot Glacier have been above freezing during at least six of the last 12 years, more than any such period in the last 110 years, according to Oregon Climate Service calculations.

Scientists in the University of Washington's Climate Impacts Group predict the Northwest will warm nearly as much in the next 20 years as it has in the last 100, about a degree Fahrenheit.

Mount Hood is not the only mountain losing its ice. Glaciers are vanishing from Europe to Africa to North America.

"It's almost universal that all glaciers are retreating," said Peter Clark, an Oregon State University professor who's an authority on glaciers. "The signs of retreat are dramatic and accelerating."

It signals that "the cause of that change is overwhelming other factors," he said. "The fingerprint of global warming is increasing on a global scale."

There is wide agreement among scientists that human burning of fossil fuels has driven greenhouse gases to their highest levels in at least 600,000 years, warming the Earth.

Portland State researchers have built upon measurements the Mazamas climbing group began in the 1920s. The analyses show Eliot Glacier has been shrinking almost since scientists first described it at the turn of the last century.

Mount Hood's glaciers are especially vulnerable to global warming because they are closer to warm ocean weather than ice in many other mountain regions.

"In 20 years, it's going to look a lot different, without a doubt," said Andrew Fountain, an associate professor at Portland State heading the research project, which examines and catalogs western glaciers. "The glaciers are continuing to retreat. They're getting a lot smaller. The glaciers today look a lot different than 20 years ago."

Studies that show the glaciers receding do not surprise climbers of Mount Hood, who say they now skip certain routes to the summit because rocks and ice once locked solidly in place now break loose.

"Warming and the receding glaciers are very much affecting the recreation potential and the dangerousness of it on all sides of the mountain," said Vera Dafoe, who has long led hikes on the mountain for the Mazamas. "It has changed enormously."