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Sea levels may surge on loss of ice: report

INCREASING loss of ice from Antarctica and Greenland could cause sea levels to exceed United Nations estimates by 2100, an Australian government-backed report said, with the extent of the rise still uncertain.

The UN Climate Panel said seas could rise by 18-59 centimeters by 2100. It also raised the possibility of an additional 20-centimeter rise if polar ice sheets dumped ever greater amounts of ice into the ocean. That assessment was based on scientific knowledge up to 2005.

"There is now emerging evidence that sea level rise by 2100 might exceed this," said the report released yesterday that reviews the latest science.

"Although it is unlikely that total sea level rise by 2100 will be as high as 2 meters, the probable upper limit of a contribution from ice sheets remains uncertain," said the report by the Antarctic Climate and Ecosystems Cooperative Research Centre in Hobart, Tasmania.

A rise of even 1 meter would force millions along Bangladesh's low-lying coast to move inland and trigger mass migration in Vietnam's Mekong Delta. Major coastal cities around the globe would need taller sea defenses or risk being swamped.

"The ice that's being lost is Antarctica is being lost not by surface melt. The continent is very cold. But it's being lost by increasing discharge from glaciers," Ian Allison, one of the report's authors, said in an online briefing yesterday.

"Some of the large glaciers in West Antarctica have sped up and they are pushing more ice out into the ocean," said Allison, leader of the Australian Antarctic Division's ice, ocean, atmosphere and climate program.

The same was also occurring in Greenland, in addition to increased melting of ice near the coast.

The report says sea levels were rising at the upper end of UN climate panel projections and that evidence suggested the Greenland and Antarctic ice sheets were contributing more to present sea-level rise than was previously estimated.

The total ice stored in ice sheets on both landmasses would raise sea levels by nearly 65 meters if it all melted.

East Antarctica, where most of the ice is locked up, remains stable for now, studies show. But in West Antarctica, much of the ice sits on bedrock up to 2 kilometers below sea level and was at great risk of collapse if warming seas eroded protective ice shelves.


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