Ice bridge broken asunder
Antarctic: Wilkins Ice Shelf loses stabilising link
Münster (upm), 6th April 2009
The ice bridge on Wilkins Ice Shelf in the Antarctic is broken.
Foto: Terra SAR-X ScanSAR, DLR
The ice is broken: a strip of the Wilkins Ice Shelf in the Antarctic – which was once 15 kilometres wide, joined the two islands of Charcot and Latady and had a stabilising effect on the Ice Shelf – was completely destroyed in April 2009 as a result of a new break-up. The ice bridge had already shrunk to a width of 900 metres at its narrowest point after the last spectacular break-up in the summer of 2008. Researchers at the Universities of Münster and Bonn expect a further loss of ice on the Wilkins Shelf in the current break-up phase.
Dr. Angelika Humbert from the Geophysics Institute at the University of Münster and her colleague Dr. Matthias Braun from the University of Bonn have been following the development of the Wilkins Ice Shelf via satellite for years, including three break-up phases in 2008. The team of researchers has found out that failure zones developed as a result of past break-up events. Humbert says: “In the past month we observed on high-resolution images of the German TerraSAR-X satellite that the ice bridge deformed. Partly this deformation is caused by the creep of ice. The shape of the ice bridge and the adjacent ice melange provided additionally an ideal surface for storms. Both contributions led to the subsequent disruption.”
And what of the future? “In the current break-up phase,” says Humbert, “we are expecting an ice-loss of around 800 square kilometres. But as cracks have already formed further south than we first assumed they would, the loss may well rise to 3,700 square kilometres,” she predicts. The break-up of the strip of ice means the loss of a stabilising link for the ice shelf. As Humbert explains, “An ice shelf is like a taut membrane. If one of the membrane’s links comes loose, a new balance has to be found. This is what happens in the case of the Wilkins Ice Shelf and means a loss of mass.”
The ice remaining after the current break-up – at least 8,000 square kilometres – is, however, still free of any visible failure zones, say the scientists. As Humbert points out, “At the moment we have no indication that there could be a complete collapse of the Wilkins Ice Shelf.”
