Scientists plan to drill deep into the ice of the Antarctic to see what the materials deposited four kilometres deep can reveal about sudden changes in climate up to half a million years ago - and therefore about whether the ice might melt due to climate changes today.

The Pounds 8 million project, which will begin in November, will be carried out in one of the most hostile places on the planet: scientists will work at minus 50 Celsius in blizzards, and on an ice plateau that can be reached only by travelling by tractor over thousands of kilometres of featureless snow.

The only previous such European drilling expedition, in Greenland, showed that at times the climate has changed very rapidly, says Carol Williams, co-ordinator of the polar programme at the European Science Foundation, which is organising the project.

"It is possible to get a climate change within a 25-year period," she says.

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ESF says that the behaviour of the Antarctic ice sheet is the largest single uncertainty in predicting how world sea levels will change under global warming, yet we have only a primitive understanding of the relationship between ice sheets and climate.

The dangers of our ignorance were highlighted recently when coastal ice shelves in the Antarctic broke up, creating icebergs the size of Luxembourg: this might have been caused by human induced global warming.

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The group, which will include scientists from the British Antarctic Survey, will drill the two holes in the centre of Antarctica, at Concordia and Droning Maudland.

By studying the composition of the ice at various levels - such as gas bubbles compressed in the ice - they will be able to build up a picture of the composition of the atmosphere at the times ice was deposited. "We're hoping to go back through several interglacial cycles," says Dr Williams.

Data will be fed into computer models of climate change to help them to predict future climate.

Dr Williams said that they may also find primitive bacteria at the bottom of the ice cores, which could throw light on evolution and on ecology.

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The project is called Epica (European Ice Core Project in Antarctica). Evidence is mounting from the Antarctic about climate warming: the UK Faraday station in the Antarctic Peninsula has experienced a 2.5 C warming in the past 50 years; and French glaciologists have reported increases in snowfall in the region, which is consistent with a warming atmosphere.