Wednesday, March 28, 2012

Scientists pin down historic sea level rise

LONDON (Reuters) - The collapse of an ice sheet in Antarctica up to 14,650 years ago might have caused sea levels to rise between 14 and 18 metres (46-60 feet), a study showed on Wednesday, data which could help make more accurate climate change predictions.

The melting of polar ice could contribute to long-term sea level rise, threatening the lives of millions, scientists say.

Sea levels have increased on average about 18 centimetres (7 inches) since 1900 and rapid global warming will accelerate the pace of the increase, experts say, putting coastlines at risk and forcing low-lying cities to build costly sea defenses.

Scientists last month said that thinning glaciers and ice caps were pushing up sea levels by 1.5 millimetres a year, and experts forecast an increase of as much as two metres by 2100.

A very rapid sea level rise is thought to have occurred 14,650 years ago but details about the event have been unclear.

Some past sea level records have suggested glacier melt led to a 20 metre increase in less than 500 years.

But uncertainty lingered about the source of the melt, its force and its link to the changes in climate. More