Global warming causing massive ice chunks to break off from Antarctic shelf

Massive ice chunks are crumbling away from a shelf in the western Antarctic peninsula, researchers said on Wednesday, warning that 1,300 square miles of ice - an area larger than Luxembourg - was in danger of breaking off in coming weeks.

Last Updated: 5:15PM BST 30 Apr 2009

The Wilkins Ice Shelf had been stable for most of the last century, but began retreating in the 1990s. Researchers believe it was held in place by an ice bridge linking Charcot Island to the Antarctic mainland.
But the 127-square-mile bridge lost two large chunks last year and then shattered completely on April 5.

"As a consequence of the collapse, the rifts, which had already featured along the northern ice front, widened and new cracks formed as the ice adjusted," the European Space Agency said in a statement Wednesday on its Web site, citing new satellite images.
The first icebergs broke away on Friday, and since then some 270 square miles of ice have dropped into the sea, according to the satellite data.
"There is little doubt that these changes are the result of atmospheric warming," said David Vaughan of the British Antarctic Survey.
The falling away of Antarctic ice shelves does not, in itself, raise sea levels, since the ice was already floating in the sea. But such coastal tables of ice usually hold back glaciers, and when they disintegrate that land ice will often flow more quickly into the sea, contributing to sea-level rise.
The Wilkins shelf, which is the size of Jamaica, lost 14 per cent of its mass last year, according to scientists who are looking at whether global warming is the cause of its breakup.
Average temperatures in the Antarctic Peninsula have risen by 2.5 Celsius over the past 50 years - higher than the average global rise, according to studies.