Scientists warn of danger from Antarctic ice melt

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SEA LEVELS are likely to rise faster and higher than previous predictions suggested, say scientists who have finished the first accurate satellite study of the thickness of the Antarctic ice sheet.

A four-year research project to measure the Antarctic ice has found that it has contributed little to rising sea levels this century - but paradoxically this means that the loss of land to the sea in the next century is likely to be greater than forecast so far.

The results of the study indicate that for the past 100 years, when sea levels have risen by a global average of 18cm (7in), factors such as the thermal expansion of the oceans and melting mountain glaciers have played a far greater role than the melting of the Antarctic ice sheets.

Professor Duncan Wingham, of University College London and leader of the international project team, said: "As a consequence of our research we should be able to produce more accurate predictions of future sea-level rises. Indeed, it is possible that the consequences of global warming on sea level rise has been underestimated."

Professor Wingham said it is reasonable to speculate that the rise in sea level next century is likely to be nearer to the higher predictions of 80cm (31in) rather than the lower predictions of 50cm (20in).

The researchers, who publish their results in the journal Science, collected more than four million radar measurements of the Antarctic ice between 1992 and 1996, which showed that the ice sheet's thickness changed by an average of less than 1cm.

"Many millions of people throughout the world live within one metre of sea level," Professor Wingham said. "They could all be under water in two centuries if models of the thermal expansion of the ocean due to global warming are correct.

"These findings make the Antarctic ice sheet look an unlikely source for the sea level rise we have observed this century. If this is the case we now have a problem explaining the rise," he said. "Other sources of rise must be underestimated. In particular it is possible that the effect of global warming on thermal expansion is larger than we thought."