Sea levels could rise ‘twice as much’ as previous forecasts, scientists warn Sea levels will rise by twice as much as previously forecast, researchers have found. By the end of the century […]

Sea levels will rise by twice as much as previously forecast, researchers have found. By the end of the century sea levels will rise by 65cm – more than two feet – according to the latest projections.

Until now a rise of 30cm by 2100 has been the widely accepted figure.

Such rises are feared to be likely to cause “significant difficulties” for coastal cities and low-lying regions, especially once storm surges are taken into consideration.

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‘Significant difficulties’

Since 1993 sea levels have been rising by about 3mm a year, meaning they have risen more than 7cm in the last 25 years, but a study by US researchers has concluded the rise will accelerate.

The research was published in the journal Proceedings of the National Academy of Sciences.

Professor Steve Nerem, of the University of Colorado Boulder and one of the co-authors of the study, said even a total of 65cm was a “conservative estimate”.

“This is a game-changer as far as the climate change discussion goes.”

“Our extrapolation assumes that sea level continues to change as it has over the last 25 years. Given the large changes we are seeing in the ice sheets today, that’s not likely.”

He said rising concentrations of greenhouse gases increased the temperature of air and water, causing sea levels to rise in two ways.

The first of these was warmer water expanding, with this “thermal expansion” of the oceans having contributed around half of the 7cm global mean sea level rise over the last 25 years.

Game-changer

The second was that of melting ice flowing into the oceans from places such as Greenland and Antarctica.

Co-author Gary Mitchum, a professor at the University of South Florida College of Marine Science, said the acceleration predicted by models had now been detected directly from their observations.

He said: “I think this is a game-changer as far as the climate change discussion goes.”

Bangladesh and the Maldives are among the regions of the world most threatened by rising seas.

The UK is also at risk, with East Anglia likely to face more flooding. London is also at risk from surges and there are fears the Thames Barrier will need to be improved or replaced.