Antarctic Ice Shelf All But Lost

By LiveScience Staff, LiveScience

A vast shelf of ice in Antarctica is hanging on to the continent bya thread and is not expected to survive, scientists announced today.

The Wilkins Ice Shelf is experiencing further disintegration that could collapse an ice bridge connecting the shelf toCharcot Island. Since the connection to the island helps to stabilizethe ice shelf, it is likely the breakup of the bridge will put theremainder of the ice shelf at risk, the researchers said.

The disintegration is evident in images from the European Space Agency's Envisat satellite.

The Wilkins Ice Shelf, a broad plate of floating ice south of SouthAmerica on the Antarctic Peninsula that is connected to Charcot andLatady Islands, had been stable for most of the last century before itbegan retreating in the 1990s. A major breakup was spotted in May, the second this year.

This third significant breakup is puzzling because it occurred in the Southern Hemispheric winter. It's also behaving differently than previous breakups.

"The scale of rifting in the newly-removed areas seems larger, andthe pieces are moving out as large bergs and not toppled,finely-divided ice melange," said Ted Scambos from the U.S. NationalSnow and Ice Data Center.

The Antarctic Peninsula's atmosphere has experienced more warming than any otherpart of the southern-most continent; in the past 50 years, it hasexperienced 4.5 degrees Fahrenheit (2.5 degrees Celsius) of warming. The warming has been so drastic because the peninsula is sandwichedbetween a region with substantially rising air temperatures and a warming ocean.

But warm water seems to be at least partly to blame for the recent disintegration, Scambos said.

In the past 20 years, seven ice shelves along the peninsula haveretreated or come apart, including the spectacular 2002 breakup ofthe Larsen B Ice Shelf.The entire Wilkins shelf, before the recent breakups, covered about6,180 square miles (16,000 square kilometers — about the size ofNorthern Ireland).

"Wilkins Ice Shelf is the most recent in a long, and growing, listof ice shelves on the Antarctic Peninsula that are responding to therapid warming that has occurred in this area over the last fiftyyears," said David Vaughan of the British Antarctic Survey."Current events are showing that we were being too conservative whenwe made the prediction in the early 1990s that Wilkins Ice Shelf wouldbe lost within thirty years - the truth is it is going more quicklythan we guessed."

Meanwhile at the top of the world, melting has become so rapid that scientists say the North Pole could be ice-free this summer.

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