National Geographic News
It's an oft-repeated statistic that the glaciers at Montana's Glacier National Park will disappear by the year 2030.
But Daniel Fagre, a U.S. Geological Survey ecologist who works at Glacier, says the park's namesakes will be gone about ten years ahead of schedule, endangering the region's plants and animals.
The 2030 date, he said, was based on a 2003 USGS study, along with 1992 temperature predictions by the UN's Intergovernmental Panel on Climate Change (IPCC).
"Temperature rise in our area was twice as great as what we put into the  model," Fagre said. "What we've been saying now is 2020."
The 2020 estimate is based on aerial surveys and photography Fagre and his team have been conducting at Glacier since the early 1980s. A more standardized measure of what's happening to a glacier comes from arduous documentation of its mass, which requires—among other techniques—multiple core samples.
Fagre said the 2020 estimate could be slightly revised after his team conducts the mass measurements—hopefully this year—and their computer models are retooled with current temperatures.
Nonpolar ice is disappearing all over the globe, Fagre said. Major glaciers have entirely disappeared from the Andes, and the Himalaya have lost a third of their snow. (See video of Alpine glaciers melting.)
Animals at Risk as Glaciers Melt
Fagre is concerned about ecological implications of glacier melt.
"A lot of our sensitive and rare plants are associated with the edges of glaciers," he said.
At first, retreating glaciers will expose more growing area for plants. But eventually plants will crowd the area, and reduced water could cause drying and die-offs.
And as glaciers retreat, the streams they feed can become intermittent, he added.
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