Ice bridge holding Antarctic ice shelf cracks up

OSLO Sat Apr 4, 2009 6:18pm EDT

1 of 2. A 20 metre-high ice cliff forming the edge of the Wilkins Ice shelf on the Antarctic Peninsula is seen from a plane January 18, 2009.

Credit: Reuters/Alister Doyle

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OSLO (Reuters) - An ice bridge which had held a vast Antarctic ice shelf in place for hundreds of years at least shattered on Saturday and may herald a wider collapse linked to global warming, a leading scientist said.

"It's amazing how the ice has ruptured. Two days ago it was intact," David Vaughan, a glaciologist with the British Antarctic Survey, told Reuters of a satellite image of the Wilkins Ice Shelf. "We've waited a long time to see this."

The satellite picture, by the European Space Agency (ESA), showed that a 40-km (25 mile) long strip of ice believed to pin the Wilkins Ice Shelf in place had snapped at its narrowest point of about 500 meters wide off the Antarctic Peninsula.

The break left a jumble of huge flat-topped icebergs in the sea. The loss of the ice bridge, which was almost 100 km wide in 1950 and had been in place for hundreds of years at least, could allow ocean currents to wash away more of the Wilkins.

"My feeling is that we will lose more of the ice, but there will be a remnant to the south," Vaughan said. The remaining shelf is about the size of Jamaica or the U.S. state of Connecticut.

Temperatures on the Antarctic Peninsula, the which snakes up toward South America, have risen by up to about 3 Celsius (5.4 Fahrenheit) in the past 50 years, the fastest rate of warming in the Southern Hemisphere.

"We believe the warming on the Antarctic Peninsula is related to global climate change, though the links are not entirely clear," Vaughan said. Antarctica's response to warming will go a long way to deciding the pace of global sea level rise.

Nine other shelves have receded or collapsed around the Antarctic Peninsula in the past 50 years, often abruptly like the Larsen A in 1995 or the Larsen B in 2002 further north, and shrinking maps of the frozen continent.

The trend is widely blamed on climate change caused by heat-trapping gases from burning fossil fuels.

Vaughan landed on the narrow ice bridge, which jutted about 20 meters above the sea, in January with a group of scientists and two Reuters reporters. He predicted that it would snap this year.

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