Ice melt may spell drought

Losses in Arctic could result in less rainfall here

Jim Erickson, Rocky Mountain News

Friday, March 16, 2007

It's not just about hungry polar bears.

If Arctic sea ice continues to shrink in coming decades, Colorado could see less rain and snow and may suffer more frequent droughts, said Mark Serreze of the National Snow and Ice Data Center at the University of Colorado.

That's because changes in the extent of Arctic sea ice can alter weather patterns across much of the Northern Hemisphere.

Some climate simulations indicate that continued ice loss could lead to increased precipitation in western and southern Europe, while the American West could get shortchanged.

"Now whether this is exactly what will occur, we're not sure," he said. "But the real take-home message here is that what happens up there can affect us down here."

Serreze and two Boulder colleagues reviewed dozens of recent Arctic ice research papers for an article published today in the journal Science.

The National Snow and Ice Data Center tracks the annual swelling and shrinking of the floating shell of sea ice that blankets the top of the world.

The cap shrinks each summer to roughly the size of the 48 contiguous U.S. states, then grows each winter.

The summertime extent of the polar ice layer has been declining since the late 1970s, with especially steep drops over the past five years.

If the trend continues, one computer simulation suggests that the Arctic could become nearly ice-free in September between 2040 and 2050.

The losses are shrinking the habitat available to polar bears, who hunt from the ice. But as Serreze and his colleagues point out, other changes could be in store thousands of miles away.

The ongoing sea-ice decline could reduce the severity of Arctic cold fronts dropping into Colorado, reducing snowfall and impacting mountain snowpacks, the ski industry and the winter wheat crop, he said.

ericksonj@RockyMountainNews.com or 303-954-5129