The European Space Agency says satellite images show icebergs have begun to calve from the northern front of the Wilkins Ice Shelf in Antarctica.

ESA scientists said the images indicate the huge shelf has become unstable following the collapse three weeks ago of the ice bridge that linked the Antarctic mainland with Charcot Island. That ice bridge, said the ESA, effectively formed a barrier pinning back the northern ice front of the central Wilkins Ice Shelf. It collapsed April 5, removing about 127 square miles of ice.

Radar images from the ESA's Envisat satellite and the German Aerospace Center's TerraSAR-X satellite show approximately 270 square miles of ice have been lost from the Wilkins Ice Shelf.

"The retreat of Wilkins Ice Shelf is the latest and the largest of its kind," said David Vaughn of the British Antarctic Survey. "Eight separate ice shelves along the Antarctic Peninsula have shown signs of retreat over the last few decades. There is little doubt that these changes are the result of atmospheric warming on the Antarctic Peninsula, which has been the most rapid in the Southern Hemisphere."

Satellite images documenting the break-up of the Wilkins Ice Shelf are available at http://www.esa.int/esaEO/SEMWZS5DHNF_index_0.html.