The thinning of one part of an ice shelf can speed up ice movement in another part of the ice shelf up to 900 kilometres away, a computer model suggests. The finding is concerning because many ice shelves are already being thinned by warm sea water flowing beneath them.
of the Potsdam Institute for Climate Impact Research in Germany has been using a computer model of ice shelves to explore the consequences of this thinning. Her team recently ran simulations to see what happens when ice shelves thin by 1 to 10 metres over areas of 20 by 20 kilometres.
According to their results, even such highly localised thinning can have immediate impacts hundreds of kilometres away, Reese told . For example, in the model, thinning at the western coast of the Ross Ice-Shelf near Ross Island immediately causes an increased outflow of ice from the Bindschadler Ice Stream, located more than 900 kilometres across the ice shelf.
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Because ice shelves float on the ocean, sea level does not rise as they thin. However, ice-shelves hold back land-based glaciers flowing into the ocean. Some glaciers in the Antarctic are already speeding up and dumping more ice in the sea, thereby raising global sea levels.
The simulations reveal which areas of ice shelves are likely to trigger an especially strong response as they thin. 鈥淲e can think of this as a risk map identifying the most critical ice-shelf regions that induce a strong response 鈥� in either magnitude or distance or both 鈥� on the overall flow of the Antarctic Ice Sheet,鈥� said Reese. 鈥淚t鈥檚 critical because the most relevant regions are often located in regions easily accessible to the intrusion of warm ocean waters.鈥�
鈥淲ith her map, glaciologists can now direct their attention to changes in relevant ice-shelf regions,鈥� says of the University of Erlangen-Nuremburg.
