Sea rise could be double that predicted, drenching coastal cities - study

Global seas could rise nearly twice as much as previous, widely accepted estimates, according to a new study saying low-lying cities face possible disaster by the end of the century.

Sea levels could surge more than 90cm by the year 2100 from melting Antarctic ice alone, on top of a 90cm rise already predicted, said the study by two American researchers, that appeared in the science journal Nature.

That same Antarctic ice melt could add nearly 15 metres of sea-level rise by the year 2500, it said.

The earlier, commonly accepted prediction was made by the United Nations Intergovernmental Panel on Climate Change in 2013 estimating global sea levels rising more than 90cm by 2100.

"This could spell disaster for many low-lying cities," said co-author Robert DeConto, professor of geosciences at the University of Massachusetts at Amherst, in a statement.

Boston, for example, could see about 1.5m of sea level rise at the end of the century, he said.

Other low-lying cities often cited as being in jeopardy of rising sea levels include London, New York, Shanghai, Hong Kong, Sydney, Australia and Venice, Italy.

The findings should sound an alarm bell for more greenhouse gas emission cuts, said co-author David Pollard, a senior scientist at Pennsylvania State University's Earth and Environmental Systems Institute.

While the findings are "worst-case" possibilities, they "should be considered seriously," he said.