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Thursday, 27 December, 2001, 20:16 GMT
Low probability of ice collapse
Ice, Nasa
Viewed from space: The ice is crucial to future sea levels
By Christine McGourty, science correspondent, in the Antarctic

Scientists think there is just a one in 20 chance that the West Antarctic Ice Sheet (WAIS) will collapse in the next 200 years.


More data on the ice sheet is urgently required to be more certain about the future of the ice sheet and possible future sea-level rises

Dr David Vaughan, Bas
The integrity of the WAIS is crucial to future sea levels; if all the ice melts in this region of the White Continent, it could raise the oceans by several metres.

The 5% probability of disintegration has been worked out by researchers commissioned by the British Government. Their work will be published in the journal Climate Change next month.

It is the first time a risk assessment of a WAIS collapse has been attempted.

'Health warning'

The West Antarctic Ice Sheet contains about 13% of all the ice in Antarctica, and scientists believe it has melted in the past - about 120,000 years ago when temperatures were 7-10 degrees Celsius warmer than they are today.


In parts of the West Antarctic, temperatures are now rising much faster than in the rest of the world, and the researchers involved in the UK study have concluded there is now a one in 20 chance in the next two centuries of the ice sheet once again collapsing.

Lead scientist Dr David Vaughan, of the British Antarctic Survey (Bas), said: "Although this study shows the probability of ice sheet collapse is reasonably low, there's a huge health warning attached.

"The potential impacts of a major change in the West Antarctic Ice Sheet are severe - fantastically expensive for developed nations with coastal cities, and just dire for poor populations in low-lying coastal areas.

'Managed retreat'

"This is the first time a risk assessment of ice sheet collapse has been attempted and it is the best estimate we can make based on the current information. More data on the ice sheet is urgently required to be more certain about the future of the ice sheet and possible future sea-level rises."

The research, carried out for the Department for Environment, Food and Rural Affairs (Defra), concluded that these rises would be spread out over at least several centuries and probably much longer. It would be at most a one-metre rise per century, which is about five times the current rate of sea-level rise.

It said: "If this occurred, it would be slow enough for a managed retreat from low-lying coastal areas, and a progressive raising of flood defences around populated areas.

"However, this would be expensive. Economists estimated a cost of 0.1% of gross domestic product for many nations such as the UK, but it would be much higher for smaller island states."

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 ON THIS STORY
The BBC's Christine McGourty in Antarctica
"The climate is warming up faster than at any time in the last two thousand years"
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