Study links Larsen ice shelf break-up to human activity

Brussels, 17 October 2006

For the first time, a team of researchers has linked the recent dramatic collapse of Antarctic ice shelves to human activity.

Temperatures in the Antarctic's central Western peninsular have risen by almost 3°C over the last 50 years, far higher than the global average rise of 0.52°C and possibly higher than anywhere else on Earth.

The most visible consequence of this temperature increase is the break-up of the region's ice shelves; in the last 30 years over 13,500 square kilometres of ice has disintegrated.

In 1995 and 2002 the world's attention was drawn to the issue by the sudden collapse of immense chunks of the northern part of the Larsen ice shelf. In the 2002 event, 3,250 square kilometres of ice shelf disintegrated. At the time, questions were raised as to whether these dramatic events were the result of human activity. Now, a team of researchers lead by Dr Gareth Marshall of the British Antarctic Survey have found evidence that this is indeed the case.

Global warming has altered the Antarctic's weather patterns. Stronger westerly winds now regularly push warmer air eastward over the 2,000m high mountains on the Antarctic Peninsula. When this happens, as it did in 1995 and 2002, the temperature over the north-east peninsular rises by around 5°C. This in turn creates the conditions which allow melt water on the surface of the ice sheets to drain down into crevasses, a process which is implicated in the break up of ice shelves.

'This is the first time that anyone has been able to demonstrate a physical process directly linking the break-up of the Larsen Ice Shelf to human activity,' explained Dr Marshall. 'Climate change does not impact our planet evenly - it changes weather patterns in a complex way that takes detailed research and computer modelling techniques to unravel. What we've observed at one of the planet's more remote regions is a regional amplifying mechanism that led to the dramatic climate change we see over the Antarctic Peninsula.'

The researchers' findings are reported in the Journal of Climate.

For more information, please visit: http://www.antarctica.ac.uk/