azcentral.com
Data document retreat of noted Montana glaciers
Susan Gallagher
Associated Press
May. 6, 2004 02:15 PM
HELENA, Mont. - When Vice President Al Gore wanted a dramatic backdrop for a 1997 speech about global warming, he chose Glacier National Park, the spectacular million-acre preserve on the country's northern edge.
Standing in front of Grinnell Glacier on a late-summer day, Gore cast the shrinking ice mass as one of the victims of a world made warmer, at least partly by indifferent polluters.
Grinnell has retreated further in the 6 1/2 years since Gore's visit, and scientists predict this glacier and the park's 26 others will be gone by 2030 if current climate trends continue. In 1850 there were an estimated 150 glaciers in what is now Glacier National Park.
"It's very conclusive that glaciers are retreating because it's warming," said Dan Fagre, an ecologist who coordinates global change research for the U.S. Geological Survey at West Glacier.
The mean summer temperature at Glacier National Park has risen by about 3 degrees Fahrenheit over the past century, and snow melts an average of two weeks earlier than it did 50 years ago, Fagre said.
"People think 'It's only 3 degrees,' " he said, but that is enormously significant in what happens to a glacier.
"It seems an open-and-shut case that human activities have exacerbated the normal warming process," said Lex Blood, founder of the Glacier Institute, which provides field education at the park. "A component of the warming going on today is probably natural. Trying to separate what's natural and what's human-caused is the issue."
But S. Fred Singer, a retired University of Virginia professor of environmental sciences, disputes the conclusions of global warming.
"It could be temperatures. It could be that they are getting less snow in the winter," said Singer, a former U.S. Weather Satellite Service director. "Glaciers have long memories. It could be they're reacting to a previous warming."
Whether the climate is warming through some natural cycle or because human activity is contributing to it through smokestack emissions, car exhaust and other gases is debated widely. What's not debatable is that glaciers react to climate, Fagre said.
"Glaciers are excellent barometers of climate change," he said.
Scientists say glacial retreat means more than a smaller icefield. Eventual consequences may include reduced late-summer streamflows as the supply of glacial water decreases. Streamside areas inhabited by birds stand to be affected by the loss of cold water that helps to sustain those areas. In some parts of the world, farmers rely on melted glacier water for crops.
Glaciers in the Northern Rockies have been in continuous retreat since the Little Ice Age, a long cooling period with glacial expansion, ended about 150 years ago, Fagre said. While he is certain the glaciers he studies are shrinking from warmth, he steers clear of the debate over what is responsible for higher temperatures.
The reduction in Grinnell can be measured both by the thinning of its ice and decline in the area covered. Fagre estimates the glacier has lost 90 percent of its ice and covers only 28 percent of its previous area. The glacier covered 2.33 square kilometers in 1885. In 2001 the measurement was 0.71.
Glaciers in the park's Blackfoot-Jackson Glacier Basin dwindled from 21.6 square kilometers in 1850 to 7.4 in 1979.
"Most of these large glaciers have shrunk to less than a third, some a quarter, of what they used to be," Fagre said. "We are definitely seeing some significant, climate-driven changes here. That part is indisputable."
But some of the evidence is mixed. Fagre notes the rate of retreat in Glacier actually has slowed in recent decades. The degree of retreat from about 1917 to 1940 was greater than what has happened in the years since.
And there are examples of glaciers still advancing. Hubbard Glacier in the St. Elias Mountains of Southeast Alaska is perhaps the best known; Hubbard has advanced steadily for about 110 years.
Twice in the last 18 years, the glacier's advancing snout has sealed off Russell Fiord, turning it into a stream-fed lake. The first massive dam of ice ruptured in 1986, releasing a flood of water and freeing porpoises and other animals trapped for several months by the advancing ice.
After 1986 the glacier continued to advance into Russell Fiord and Disenchantment Bay at a rate averaging about 105 feet a year, the USGS said. In 2002 the glacier again blocked the fiord, this time for 2 1/2 months, until the dam broke after heavy rain. Scientists expect Hubbard to continue advancing, and to block Russell Fiord again.
But advancing glaciers are the exception.
"Of the 11 (Alaska) mountain ranges that had large Little Ice Age cover, there are only three or four that currently support advancing glaciers," said Bruce F. Molnia, who has studied glaciers for the USGS since 1974. "The last time we did a count, 2002-03, there were only about 15 glaciers in Alaska that were advancing."
More than half of those are in the westernmost coastal mountains and the St. Elias range.
"You get the strange, localized phenomena of glaciers responding to regional climate," Molnia said. "There are lots of complications based on altitude, proximity to the ocean, available moisture."
Singer believes part of the debate over warming is driven by people who make money from it.
"Nongovernment organizations are doing well, thanks to this," he said. "They're getting a lot of contributions. The government spends about $2 billion a year on climate research. Bureaucrats like it because their perks are growing, their staffs are growing."
"There are people who believe it is warming and it is bad for us. There are also people who believe it is warming and that would be good for us."
But for George Ostrom, a northwestern Montana resident who has hiked in Glacier National Park for a half-century, the retreat of glaciers is both obvious and irrelevant.
"They've shrunk a lot in my lifetime," Ostrom said. "It isn't anything that upsets me or dismays me or anything else. It's just life here on Earth."
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