Glaciers melting at fastest rate in 10,000 years

ARAPAHO GLACIER, Colo. — The state's largest glacier is shrinking fast, and University of Colorado researchers suspect global warming is playing a role.

The surface of the 62-acre Arapaho Glacier along the Continental Divide west of Boulder has dropped 100 to 130 feet since 1960, according to recent university reports.

A third university analysis concludes that the surface of the 25-acre Arikaree Glacier, about five miles north of the Arapaho, has also sunk some 66 feet since 1965.

The three reports are the first to document significant present-day declines in Colorado's pint-size Front Range glaciers, which are clustered along the Continental Divide from Rocky Mountain National Park south to I-70.

"We can argue about the rate of decline, but I think we can say confidently that both of them are losing ice — and they've been losing it fairly seriously," said university hydrologist Nel Caine, author of the Arikaree report.

Researchers say there is no reason to believe that other Front Range glaciers aren't experiencing similar declines. Some of them could be gone in a few decades.

Just two years ago, at the height of Colorado's multiyear drought, two year-round ice patches along the Continental Divide disgorged ancient bison horns that have been radiocarbon dated between 2,090 and 2,280 years old.

The animal remains suggest that, in some cases, ice along the divide has retreated to levels unseen since before the time of Christ.

"Over the last couple of decades, and especially over the last 10 years, we have entered a period of warming and retreat that is as great, or greater, than any we know of since the end of the last ice age" 10,000 years ago, said glaciologist Tad Pfeffer, of the university's Institute of Arctic and Alpine Research, or INSTAAR.

"The Front Range glaciers and snowfields could be gone in a couple of decades," Pfeffer said.

"Are we directly responsible for this? Is this the smoking gun that says this is caused by fossil-fuel emissions? That's a harder question to answer," he said.

The loss of glaciers and the so-called perennial snowfields would redefine places such as Rocky Mountain National Park. It would reduce habitat for fish that rely on late-summer runoff from glacial sources. Some alpine plants and high-altitude forests also could suffer.