SAN FRANCISCO--One of the United States' most beautiful landmarks may soon have to change its name. Glacier National Park in Montana, which once boasted 150 of the spectacular rivers of ice, is now down to 25, and the most recent data show that the remainder "may be gone in our lifetimes," an ecologist said here yesterday at a meeting of the American Geophysical Union. Other than the aesthetic loss, the disappearance of glaciers across the American West could cause huge problems for a regional population that is 85% dependent on mountain water and already coping with shortages.
Compared to Earth's more permanent polar ice caps, mountain glaciers are transient. The glaciers of the American West, for example, formed about 8000 years ago--several millennia after the end of the last ice age--during a prolonged cold period. Since then, they have become a scenic fixture of the landscape, drawing millions of visitors a year, and also act as a source of freshwater, for ecosystems as well as humans, during their annual spring and summer runoffs.
The problem now is that "all of the glaciers are disappearing," said ecologist Daniel Fagre of the U.S. Geological Survey's Northern Rocky Mountain Science Center, located in Glacier National Park. The latest surveys conducted by the organization show that the glaciers are, on average, 1.7 meters thinner each year--a decline much more rapid than expected. One of the hardest hit is the Grinnell Glacier, which had ice as much as 300 meters thick when it was discovered in the 19th century. Now that ice is completely gone in some places, exposing soils that have not seen daylight in thousands of years. Bighorn sheep are grazing in areas that until recently were overlain by ice, Fagre said.
Warmer temperatures are only part of the problem, explained geographer Thomas Painter of the University of Utah, Salt Lake City, who presented his own research on snowpack in the West at the meeting. Also contributing is carbon black, known more commonly as soot, which continually rains down on the glaciers but tends to concentrate on the surface of the ice. By the calculations of his research team, Painter said, soot increases heat absorption from the sun's rays by 43%. That provides "yet another reason" to limit carbon black from industrial emissions, says climatologist Claire Parkinson of NASA's Goddard Space Flight Center in Greenbelt, Maryland.
Others are more skeptical about carbon black's contribution. Environmental scientist Mauri Pelto of Nichols College in Dudley, Massachusetts, says it's "overblown in terms of glaciers," which aren't "clean by any means due to wind-carried dust from surrounding areas." Also, not all glaciers in the park are shrinking rapidly, he says, adding that soot probably affects the accumulation of the annual snowpack more.