Antarctica's Wilkins Ice Shelf eroding at an unforeseen pace
Scientists say the breakup is a harbinger of what's to come if the region continues warming.
A crumbling ice shelf along the West Antarctic Peninsula has become the latest polar poster child for global warming.Skip to next paragraph
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This week, researchers in the United States, Britain, and Taiwan released images of long stretches of ice shearing away from the shelf. What started with the loss of a relatively thin, 26-mile-long iceberg at the end of February cascaded into the loss of 160 square miles of ice by the end of last week.
Its erosion won't affect sea levels. Like an ice cube in a filled cup, it's already in the water. And the handful of glaciers that feed into the shelf, called the Wilkins Ice Shelf, are small. Still, researchers say, the event represents a marker. The region has seen unprecedented rates of warming during the past 50 years. Two of the 10 shelves along the peninsula have vanished within the past 30 years. Another five have lost between 60 percent and 92 percent of their original extent. Of the 10, Wilkins is the southernmost shelf in the area to start buckling under global warming's effects.
"Wilkins is a stepping stone in a larger process," says Ted Scambos, a glaciologist at the National Snow and Ice Data Center in Boulder, Colo., who discovered the breakup in satellite images. "It's really a story of what's yet to come if the mainland of Antarctica begins to warm."
So far, the shelf has lost about 3 percent of its total extent, which covers an area more than twice the size of Rhode Island and is up to 820 feet thick. But all that sits between the shelf's new seaward edge and a vast expanse of much weaker shelf ice is what researchers dub a "thread" of strong ice. And Wilkins's erosion is happening faster than researchers projected.
"In 1993, we predicted that this was going to be a vulnerable ice shelf," says David Vaughan of the British Antarctic Survey. "But we got the time scales completely wrong. We were saying 30 years at that time, and now it's happened within 15."
Glaciologists are concerned about Antarctica's ice shelves because most of them represent brakes of solid ice that slow the glaciers' flow to the sea. Without those brakes, the glaciers would surge, calve into icebergs, and significantly raise the sea level.