Anchorage Daily News | Craig Medred | Oct. 13, 2008
Two hundred years of glacial shrinkage in Alaska, and then came the winter and summer of 2007-2008. Unusually large amounts of winter snow were followed by unusually chill temperatures in June, July and August. […]
Never before in the history of a research project dating back to 1946 had the Juneau Icefield witnessed the kind of snow buildup that came this year. It was similar on a lot of other glaciers too.
“In mid-June, I was surprised to see snow still at sea level in Prince William Sound,” said U.S. Geological Survey glaciologist Bruce Molnia. “On the Juneau Icefield, there was still 20 feet of new snow on the surface of the Taku Glacier in late July. At Bering Glacier, a landslide I am studying, located at about 1,500 feet elevation, did not become snow free until early August.
“In general, the weather this summer was the worst I have seen in at least 20 years.”
“It’s been a long time on most glaciers where they’ve actually had positive mass balance,” Molnia said.
That’s the way a scientist says the glaciers got thicker in the middle.
Mass balance is the difference between how much snow falls every winter and how much snow fades away each summer. For most Alaska glaciers, the summer snow loss has for decades exceeded the winter snowfall.
The result has put the state’s glaciers on a long-term diet. Every year they lose the snow of the previous winter plus some of the snow from years before. And so they steadily shrink.
Climate change has led to speculation they might all disappear. Molnia isn’t sure what to expect. As far as glaciers go, he said, Alaska’s glaciers are volatile. They live life on the edge.
“What we’re talking about to (change) most of Alaska’s glaciers is a small temperature change; just a small fraction-of-a-degree change makes a big difference. It’s the mean annual temperature that’s the big thing.
“All it takes is a warm summer to have a really dramatic effect on the melting.”
Or a cool summer to shift that mass balance the other way.
One cool summer that leaves 20 feet of new snow still sitting atop glaciers come the start of the next winter is no big deal, Molnia said.
Ten summers like that?
Well, that might mark the start of something like the Little Ice Age.
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