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Glaciers in Perspective
Fri Apr 01, 2005
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Hi, I'm Bryan Yeaton and this is The Weather Notebook.
The recipe for a glacier is surprisingly simple: gradually add snow to a below-freezing environment, making sure the bottom layers don't melt as you sprinkle on new layers, chill for several hundred years or until the frozen mass is at least 60 feet deep and voila! A glacier. But this recipe has one freaky little twist: at some point as the layers of new snow build up and crush the snow underneath into a dense conglomeration of ice crystals, a glacier takes on a life of its own. Like Frankenstein, this frozen monster starts to move, lurching inch by inch down the sides of crumpled mountains, stomping over valleys, tumbling into the sea.
Nowadays, though, these are monsters on the run. For the past century or so, most of the world's glaciers have been retreating, thinning or stagnating. And this trend has intensified sharply in recent years. University of Colorado geologist Mark Meier notes that the rate of ice loss has more than doubled since 1988, contributing significantly to the rise in sea level. Alaska's glaciers are being hit especially hard. Nearly all of the state's 2,000 valley glaciers are shrinking significantly: some disappeared altogether during the 20th century while others pulled back to reveal valleys and bays that had been ice-choked through recorded history.
This glacial decline may be a result of global warming. Whether it will persist or worsen remains an open question. After all, the past two million years have seen at least four major glacial advances and retreats. We'll need a minimum of a couple of thousand years to put the current picture in perspective.
The Weather Notebook is a production of the Mount Washington Observatory. It is supported by Subaru and the National Science Foundation.
Today's Links
Visit the Glacier Website
http://www.glacier.rice.edu/
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