Wednesday, August 30, 2006
With more glaciers than any state in the Lower 48, Washington state has emerged as a bellwether for global warming.
The signs are not encouraging.
A national environmental group recently reported that North Cascades and Mount Rainier are among the dozen national parks most susceptible to climate change.
At Mount Rainier, which has more glacial ice than the rest of the Cascades combined and is among the best studied sites in the nation, the area covered by glaciers shrank by more than a fifth from 1913 to 1994, and the volume of the glaciers by almost one-fourth, the National Park Service says. From 1912 to 2001, the Nisqually Glacier on Mount Rainier retreated nearly a mile.
Since the first stirrings of the Industrial Revolution 150 years ago, glaciers in the northern Cascades have shrunk by 40 percent, and the pace is accelerating. The South Cascades Glacier, one of the most studied in the nation, has lost roughly half its mass since 1928.
In the Olympic Mountains, glaciers have lost about one-third of their mass.
"They are the canary in the coal mine," Ed Josberger, the head of the U.S. Geological Survey's ice and climate project in Tacoma, said of the glaciers in Washington state. "They are changing fast, and this is not good."
The state's official climatologist, Philip Mote, agreed.
"Everything is now retreating, and the smaller glaciers are disappearing," said Mote, a research scientist at the University of Washington, who's guarded in attributing the changes directly to global warming but concedes that the evidence is mounting.
Glaciers are affected by two climatic conditions: snowfall, which adds to their mass during the winter, and warm temperatures, which spur melting in the summer. The amount of snow falling in the Northwest is declining, while temperatures are rising.
During the 20th century, Mote said, temperatures in the region rose about 1.5 degrees Fahrenheit. In western Washington state, Mote said, the increase was even greater, roughly 2 degrees.
Despite some heavy snowfalls in the late 1990s - in the winter of 1998-99, Mount Baker recorded a record snowfall of 1,100 inches - the overall trend is negative.
"The decline in snowfall in the Northwest has been the largest in the West, and it is clearly related to temperature," Mote said.
The glaciers in Washington state aren't the only ones retreating. From the Arctic to Peru and from Greenland and Europe to East Africa, there are reports that glaciers are shrinking.
There are exceptions. Glaciers on California's Mount Shasta, at the southern end of the Cascade range, have been growing, Mote said. Recent studies indicate that glaciers also might be growing in the Himalayas and other Asian mountain ranges.
No one is quite sure what causes these anomalies.
"The signature of human influence on climate is pretty clear on the continental scale and the regional scale," Mote said. But when it comes to smaller geographic areas, Mote said, the picture is unclear.
Other scientists are convinced that global warming has caused glaciers to retreat in the Northwest and elsewhere.
"This is what the models predicted," said Joe Reidel, the park geologist for the North Cascades National Park. "They are melting fast. There can be pauses of five or six years, but they are still shrinking rapidly."
Reidel has been studying glaciers in the North Cascades for 15 years. Scientists use everything from ice-penetrating radar to satellite imagery to on-the-ground observations to track the glaciers. They've been methodically studying the South Cascades Glacier for 50 years and observing glacial changes on Mount Rainier since the late 1800s.
"There is no question glaciers are a dramatic indicator of climate," Reidel said.
The National Park Service has been supportive of his research, Reidel said, but it's harder to find more funding through federal grants.
"Money is getting tougher and tougher to come by," he said.
Reidel thinks the glaciers and the Earth's climate might be reaching a tipping point from which there may be no recovery.
There's more carbon dioxide in the atmosphere now than at any time in the past 20 million years, Reidel said. Carbon dioxide, thought to be a key ingredient in global warming, is emitted by burning fossil fuels such as coal or oil, among other things. Research has shown that none of the other warm periods in the past 20 million years had such a high concentration of carbon dioxide in the atmosphere, he said.
"It is clear it is human-induced," Reidel said.
Scientists are still trying to determine what changes the Northwest may experience from global warming. But Reidel said it was clear that stream flows would be reduced as the glaciers shrank, affecting the region's extensive system of hydroelectric dams and salmon and other fish.
Reidel said summer flows in one drainage in the North Cascades had dropped by 25 percent; if the glaciers disappear they'll fall by another 20 percent.
"Some reservoirs get 20, 30 and even 40 percent of their water during the summer from glaciers," he said.
Reidel said no one knew for sure whether Washington state's mountain glaciers would disappear eventually.