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A huge iceberg (25 miles x 1.5 miles) appears to have dropped from the Wilkins Ice Shelf. Scientists now think that the rest of the shelf - about the size of Northern Ireland - is at risk of collapse

Satellite imagery from the University of Colorado at Boulder's National Snow and Ice Data Center shows a portion of Antarctica's massive Wilkins Ice Shelf has begun to collapse because of rapid climate change in a fast-warming region of the continent.

While the area of collapse involves 160 square miles at present, a large part of the 5,000-square-mile Wilkins Ice Shelf is now supported only by a narrow strip of ice between two islands, said CU-Boulder's Ted Scambos, lead scientist at NSIDC. "If there is a little bit more retreat, this last 'ice buttress' could collapse and we'd likely lose about half the total ice shelf area in the next few years."

In the past 50 years, the western Antarctic Peninsula has experienced the biggest temperature increase on Earth, rising by 0.9 degree F per decade. "We believe the Wilkins has been in place for at least a few hundred years, but warm air and exposure to ocean waves are causing a breakup," said Scambos, who first spotted the disintegration activity in March.

Satellite images indicate the Wilkins began its collapse on Feb. 28. Data revealed that a large iceberg, measuring 25.5 by 1.5 miles, fell away from the ice shelf's southwestern front, triggering a runaway disintegration of 220 square miles of the shelf interior. The Wilkins Ice Shelf is a broad sheet of permanent floating ice on the southwest Antarctic Peninsula roughly 1,000 miles south of South America.

The edge of the shelf crumbled into the sky-blue pattern of exposed deep glacial ice that has become characteristic of climate-induced ice shelf breakups such as the Larsen B ice shelf breakup in 2002, said Scambos. A narrow beam of intact ice about 3.7 miles wide was protecting the remaining shelf from further breakup as of March 23.

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