West Antarctic Ice Sheet Deep Structure Suggests Climate Vulnerability

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"Scientists have found a remarkable new structure deep within the West Antarctic Ice Sheet which suggests that the whole ice sheet is more susceptible to future change than previously thought.

The structure - a distinctive fold in the ice, 800m deep by 50 km long was detected using ice-penetrating radar. Ice sheets normally consist of flat layers of ice, so finding this huge fold was a complete surprise. Its presence suggests that a few thousand years ago surface ice at the Centre of the ice sheet was moving rapidly and being 'drawn down' towards the bottom of the ice sheet.

The discovery, by scientists from Bristol University and the British Antarctic Survey in collaboration with US colleagues, is revealed in a paper entitled Ice Flow Direction Change in Interior West Antarctica, published in the journal Science. Vol 305, 24 September 2004. Lead author Prof Martin Siegert of Bristol University said, 'There is a great deal of speculation that global warming may cause sea levels to rise due to the melting of ice sheets. Until now, scientific observations suggested that change to the West Antarctic Ice Sheet would be restricted to the edges implying that large-scale instability of the ice sheet is unlikely. This new discovery deep within the ice means that we need to re-think our current assessment of the risk of collapse of this ice sheet.'

EDIT

More recently the rate of the ice flow has changed from fast to slow. The direction of flow has also changed. The most likely explanation for these changes is the 'switching-off' of a large ice stream at the margin of the ice sheet several centuries ago. These changes imply that the centre of the ice sheet is more mobile than scientists previously realised, requiring them to rethink existing models."

EDIT

http://www.falkland-malvinas.com/Detalle.asp?NUM=4297