Icebergs Breaking Away from Wilkins Ice Shelf

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The latest satellite images show that icebergs have begun to break away from the northern front of the Wilkins Ice Shelf – indicating that the huge shelf has become unstable. This follows the collapse three weeks ago of the ice bridge that had previously linked the Antarctic mainland to Charcot Island. On April 24, satellite data from ESA’s Envisat satellite and the German Aerospace Centre’s TerraSAR-X satellite showed that the first icebergs had started to break away from the fragile ice shelf. A very rough estimate suggests that, so far, about 700 sq km of ice has been lost from the Wilkins Ice Shelf.

Three weeks ago, the ice bridge shattered very quickly, but it is expected that the current discharge of ice will continue for some weeks. The process where portions of a glacier’s leading edge break off as icebergs into an adjacent body of water is known as “calving” and this is occurring as a result of fracture zones that have formed over the last 15 years and which turned Wilkins into a fragile and vulnerable ice shelf.

Click here for a “movie” of the how the Wilkins Ice Shelf has changed from January 2008 to April 2009.

“The retreat of Wilkins Ice Shelf is the latest and the largest of its kind. 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,” explained David Vaughan from the British Antarctic Survey.

“The changes to Wilkins Ice Shelf provide a fabulous natural laboratory that will allow us to understand how ice shelves respond to climate change and what the future will hold for the rest of Antarctica,” Vaughan commented. “The quality and frequency of images acquired by ESA satellites mean that the break-up of Wilkins Ice Shelf can be analyzed far more effectively than any previous event. For the first time, I think, we can really begin to see the processes that have brought about the demise of the ice shelf.”

However, it is still unclear how the situation will evolve, Humbert said. “We are not sure if a new stable ice front will now form between Latady Island, Petrie Ice Rises and Dorsey Island. If the connection to Latady Island is lost, the projected loss of 3370 sq km of ice might be greater – though we have no indication that this will happen in the near future.”

Source: ESA