November 2, 2009, 3:23 pm
Like
the long tail of a sleeping dragon, northwestern Montana's jagged peaks
snake their way across several hundred square miles of ancient glacial
plains. At first glance, this slice of the Northern Rockies, with its
massive flanks carpeted by Douglas fir, spruce and lodgepole pine,
looks perfectly healthy.
But above the tree line, decades of regional warming has taken its
toll on the ecosystem's glaciers and permanent snowpacks. At summer's
end, even from a distance of 60 miles, the mountainous eastern slope of
Glacier National Park resembles a chain of dirty snow cones.
"The Little Ice Age ended about 1850," noted Dan Fagre, a U.S.
Geological Survey research ecologist at the Northern Rocky Mountain
science center in West Glacier, Mont. "We had 150 glaciers here in
1900. We only have 25 left now."
A recent paper co-authored by Fagre, appearing in the journal Climatic Change, analyzed more than 100 years of temperature data from western Montana.
It concluded that the rise in its temperature extremes and seasonal
averages "has been two to three times greater than that of the global
average."
The
authors are still trying to figure out exactly why. The end result, as
the paper notes, is that the region has undergone both "a loss of
extremely cold days as well as an increase in extremely hot days."
But inside the million-acre national park, in late afternoon on the
last day of summer, there's already an autumn-ish nip in the air. The
deciduous trees are beginning to turn and the park's remaining glaciers
have finally shed the last of their seasonal snowpacks.
Fagre gestures toward the northeastern end of Lake McDonald and the
disappearing Sperry Glacier in the distance. Ice and snow from Sperry
used to overlap onto the Lake McDonald side of the ridge, he notes. But
the glacier has shrunk to such an extent that its ice is no longer
visible from this side of the mountains.
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