Antarctic Ice Shelf hanging by its last thread

Paris, July 11 : The Wilkins Ice Shelf in Antarctica is literally hanging by its last thread, with further disintegration that is threatening the collapse of the ice bridge connecting the shelf to Charcot Island.

Since the connection to the island helps to stabilise the ice shelf, it is likely the break-up of the bridge will put the remainder of the ice shelf at risk.

The Wilkins Ice Shelf, a broad plate of floating ice south of South America on the Antarctic Peninsula that is connected to Charcot and Latady Islands, had been stable for most of the last century before it began retreating in the 1990s.

Images acquired by Envisat's Advanced Synthetic Aperture Radar (ASAR) between 30 May and 9 July 2008, shows the break-up event which began on the east rather than the on west like the previous event that occurred last month.

By 8th July, a fracture that could open the ice bridge was visible.

According to the image acquired on 7th July 2008, Dr Matthias Braun from the Center for Remote Sensing of Land Surfaces at Bonn University estimated that the area lost on the Wilkins Ice Shelf during this break-up event is about 1350 km sq., with a rough estimate of 500 to 700 km sq. in addition being lost if the bridge to Charcot Island collapses.

This break-up is puzzling to scientists because it has occurred in the Southern Hemispheric winter and does not have characteristics similar to two earlier events that occurred in 2008, which were comparable to the break-up of the Larsen-A and -B ice shelves.

"The scale of rifting in the newly-removed areas seems larger, and the pieces are moving out as large bergs and not toppled, finely-divided ice melange," said Ted Scambos from the National Snow and Ice Data Center, who uses ASAR images to track the area.

"The persistently low sea ice cover in the area and data from some interesting sources, electronic seal hats (caps worn by seals that provide temperature, depth and position data) seems to suggest that warm water beneath the halocline may be reaching the underside of the Wilkins Ice Shelf and thinning it rapidly - and perhaps reaching the surface, or at least mixing with surface waters," he added. According to Professor David Vaughan of the British Antarctic Survey (BAS), "Current events are showing that we were being too conservative, when we made the prediction in the early 1990s that Wilkins Ice Shelf would be lost within thirty years - the truth is it is going more quickly than we guessed," he added.

ANI