Melting ice raises concern

2005-10-24 08:40

Washington - European scientists and US fear the collapse of ice shelves in Greenland and Antarctica will raise ocean levels faster than estimated, said a report published on Friday in the journal Science.

The rapid breakdown of the floating ice shelves observed in recent years, the experts said, could destabilise land-based ice sheets and glaciers behind them and cause faster melting and rise in sea levels than anticipated.

Current projections for rises in sea levels do not take into account the new hypothesis, said Peter Clark, professor of geosciences at Oregon State University.

"We may be more vulnerable to sea level rise than we thought and it may be more rapid than we have anticipated," Clark said. "This is an issue we should take very seriously."

Current projections in climate models suggest that global warming during the next century or two will cause thermal expansion of water and some melting of glacial ice chiefly in Greenland.

However, that may be largely offset by increased precipitation and glacial build-up in Antarctica, leading to increased sea level of about 50cm the scientists said.

The breakdown of glaciers currently being studied, said Clark, could double the sea level rise to a full metre.

And in a span of about 1 000 years, he added, the Greenland ice sheet may disappear, raising Earth's sea level by about six metres. Glacial breakdown mechanisms currently being studied could speed that up considerably.

"It's become clear that the West Antarctic Ice Sheet, much of which sits on land that's actually below sea level, is one of the most vulnerable in the world to these types of rapid breakdowns," Clark said.

"The real problem would occur if these smaller glacial break-ups trigger larger ones, and rising sea levels by themselves might cause a feedback mechanism which would further speed up the process," the scientist added.

- SAPA