Satellite images show that icebergs have begun to calve 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.
Superimposed Envisat images show margins of the collapsed ice bridge
Credits: ESA (Annotations by A. Humbert, Münster University)
The ice bridge, which effectively formed a barrier pinning back the northern ice front of the central Wilkins Ice Shelf, collapsed on 5 April removing about 330 sq km of ice. 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 in the days that followed.
Dr Angelika Humbert from the Institute of Geophysics, Münster University and Dr Matthias Braun from the Center for Remote Sensing, University of Bonn have been monitoring the ice shelf using a combination of radar images from ESA's Envisat satellite and the German Aerospace Centre's TerraSAR-X satellite.
Wilkins Ice Shelf from January 2008 - April 2009
On 24 April, the satellite data 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.
In contrast to the ice bridge, which shattered very quickly, it is expected that the discharge of ice will continue for some weeks. The icebergs are calving 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.
TerraSAR-X image over Wilkins Ice Shelf from 23 April
Credits: DLR, ESA (Annotations by A. Humbert, Münster University)
"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 analysed 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."
Map of Antarctica
ESA's Webcam from Spaceis available to the public and features the latest Envisat images, documenting the break-up of Antarctica's Wilkins Ice Shelf.
Contact: Media Relations, Paris, tel: +33 1 5369 7155, fax: +33 1 5369 7690, email: media @ esa.int(Media inquiries only)
Source: ESA, European Space Agency