A Thin Silver Lining to Antarctic Ice Collapse

http://blog.wired.com/wiredscience/2008/03/a-thin-silver-l.html

A Thin Silver Lining to Antarctic Ice Collapse
By Brandon Keim
March 26, 2008
Categories: Climate

News of the disturbing collapse of a 160-square-mile piece of western Antarctic ice was mildly reassuring in one way: the chunk itself wouldn't immediately start to melt, or unleash glaciers into the sea.

"Scientists said they are not concerned about a rise in sea level from the latest event, but say it's a sign of worsening global warming," reported the Associated Press.

As Dylan noted in his post, Antarctic ice shelves are "the leading edges of land-based glaciers." The shelves act like dams -- and we all know what happens when a dam breaks. In 1995 and 2002, when vast portions of the Larsen B ice shelf broke off and disintegrated, glaciers soon surged towards the sea.

But researchers say that the Wilkins Ice Shelf -- the larger sheet to which the now-fallen piece belonged -- already floats in the ocean, with few glaciers flowing into it. When it collapses -- its lifespan is optimistically pegged at 15 years -- no backed-up glaciers will be released.

So that's reassuring. Or is it?

As the BBC reported last month, the British Antarctic Survey recently found "the clearest evidence yet" of glacial instabilities in West Antarctica, where three "rivers of ice" have accelerated their seaward course.

"If there is a feedback mechanism to make the ice sheet unstable, it will be most unstable in this region," said BAS researcher David Vaughan.

Could the distintegrating Wilkins Ice Shelf be part of such a feedback mechanism? Or is it just a vast, icy canary in the coal mine of Earth? I'll ask the BAS and let you know.