Scientists from the American Geophysical Union and the U.S. Geological Survey have reported that the snowpack of the Rocky Mountains, North America’s largest mountain range, has declined 20% since the 1980’s.
Greg Pederson of the Northern Rocky Mountain Science Center in Bozeman pointed his finger at warmer temps as the major cause of the decline in snowpack.
“From 1980 on, warmer spring temperatures melted snowpack throughout the Rockies early, regardless of winter precipitation,” he said. “The model in turn shows temperature as the major driving factor in snowpack declines over the past 30 years.”
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Runoff from the Rocky Mountain snows accounts for 60 to 80 percent of the annual water supply for more than 70 million people in the Western United States. The timing of snowmelt affects the levels of water available for crop irrigation and hydro-electric power. It can also influence the risk of regional floods and bush fires.
The researchers blame both natural variation – the influence of cyclic Pacific Ocean phenomena such as El Niño and La Niña, for example – and global warming from human activity for the change.
“Regardless of the ultimate causes, continuation of present snowpack trends in the Rocky Mountains will pose difficult challenges for watershed management and conventional water planning in the American West,” said study co-author Julio Betancourt.
Meanwhile, at the American Geophysical Union’s meeting in Cancun, Mexico, researchers report that the world’s highest peak, Mount Everest, is beginning to lose its snow and ice.
They report, after studies of satellite imagery of the mountain and the Sagarmatha National Park, that the Everest region in the Himalayas has been warming, and snow precipitation declining, for the last 20 years.
Everest glaciers have shrunk by 13 percent in the last 50 years and the snowline has moved 180 meters uphill. As the glaciers dwindle, the rocks and debris they carry are being exposed: The debris-covered sections of the glaciers have increased by 17 percent since the 1960s.
Once again, the researchers suspect that human-induced climate change may be responsible: This connection however is much harder to establish. But the majority of glaciers in the region are retreating at an ever-faster rate.
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