Snowmelt

Pictured above: South Cascade Glacier, Washington State. Top: 1928. Bottom: 2006. From a story in today's Seattle Times:

The pattern of shrinking in the South Cascade Glacier, as well as several glaciers in Alaska, for example, suggests a link to broader climate change, said Ed Josberger, head of the ice and climate project at the USGS office in Tacoma.

A shift in regional weather patterns in the late 1980s should have brought more snow and caused the South Cascade Glacier's shrinkage to slow. But rising summer temperatures overwhelmed the additional snow, and the glacier continues to shrink quickly.

Also, for decades the South Cascade Glacier and another glacier in Alaska were polar opposites. Because of regional weather patterns, when one shrank quickly the other did well. But now they are both rapidly shrinking.

As the story takes pains to point out, this trend has serious implications for a region dependent upon hydropower, irrigation and the health of its salmon runs.

And just in case you're one of those whose reaction is, 'C'mon, glaciers have been advancing and receding for eons,' read Coby Beck's response from his online guide, How to Talk to a Global Warming Skeptic.