There has been much speculation that global warming may cause sea levels to rise due to the melting of ice sheets. For the first time scientists have worked out the likelihood of Antarctic ice sheet collapse using engineering risk-analysis techniques. They conclude that there is a 5% chance of major sea level rise (up to 1 metre) in the next century due to disintegration of the ice covering West Antarctica, a report in January 2002 Climatic Change reveals. This study gives a realistic assessment of differing scientific opinions in a useful way for policy makers.

This novel study pooled the opinions of international experts to assess the probability of the collapse of the West Antarctic Ice Sheet (WAIS), which contains 13% of all the ice on the Antarctic continent. Currently this ice sheet is anchored to the rock beneath, much of which is below sea level. However, in past warm periods, the ice sheet thinned and disintegrated into floating icebergs. If the WAIS completely disintegrated, it would raise global sea levels by about 5 metres over several centuries. The stability of this ice sheet has been hotly debated since the 1960s.

The risk assessment was carried out by a partnership between scientists from the British Antarctic Survey and risk assessment specialists Det Norske Veritas for the UK Department of the Environment, Food and Rural Affairs (DEFRA). They conclude that the scientific community does not know enough to reliably predict the future of the West Antarctic Ice Sheet. Overall, scientists are 95% convinced that the ice sheet will not collapse completely, but there remains a 5% chance that collapse will occur in the next 200 years, enough to double present estimates of sea level rise.   

Dr David Vaughan, the principal scientist said: “Although this study shows that the scientists gave a low probability of complete ice sheet collapse, there’s a huge health warning attached.   The potential impacts of a major change in the West Antarctic ice sheet are severe – sea level rise will be fantastically expensive for developed nations with coastal cities and dire for poor populations in low-lying coastal areas”

John Spouge, co-author of the report, added: “We normally base risk assessment on experience of accidents in the past. In the case of the West Antarctic, this was impossible, and instead we tried to describe the diversity of current scientific opinion about the issue in a way that would be helpful for policy makers. Until we have done more research, no-one can be certain whether the West Antarctic Ice Sheet will disintegrate or not, and so we have to live with the possibility that it might happen. Our results show we can’t ignore it.”

Issued by British Antarctic Survey
Press enquiries to: British Antarctic Survey Press Office:
Linda Capper (w) 01223 221448, (h) 01480 880302, (m) 07714 233744.
Alison George (w) 01223 221414, (m) 07740 822229
Athena Dinar (h) 01223 513298

For more information contact:
Dr. David Vaughan, British Antarctic Survey. Tel: (m) 07785 975244, (w) +44 (0)1223 221643
John Spouge, Det Norske Veritas, Technical Consultancy +44 (0)207 716 6557
Dr. Simon J. Brown, UK Department of the Environment, Food and Rural Affairs. Tel: +44 (0)207 944 5210

Notes for editor

Ice sheet
The Antarctic ice sheet is the layer of ice up to 5000 m thick covering the Antarctic continent. It is formed from snow falling in the interior of the Antarctic which compacts into ice. The ice sheet slowly moves towards the coast, eventually breaking away as icebergs which gradually melt into the sea.

The ice sheet covering East Antarctica is very stable, because it lies on rock that is above sea level and is thought unlikely to collapse. The West Antarctic is less stable, because it sits on rock below sea level.

If the ice sheet does collapse, it is more likely to be part of a natural collapse cycle, or as a response to climatic change that occurred many thousands of years ago, rather than a response to current climatic change.

British Antarctic Survey is responsible for most of the UK’s research in Antarctica. It is a component of the Natural Environment Research Council. More information about the work of the Survey can be found on our website:

Det Norske Veritas is a Norwegian organisation whose objective is safeguarding life, property and the environment. Their website is:

Picture editors: Photographs of Antarctica and ice sheet research being carried out are available from the BAS Press Office.