Melting ice sheets threaten defences

Sea levels could rise by as much as 1.4 metres (4.6 feet) by 2100 – more than twice previous estimates – according to new studies showing that one of the Antarctic's massive ice sheets is more vulnerable to melting than previously thought.

This would inundate many densely-populated regions, as well as threaten the flood defences of many coastal cities from San Francisco to St Petersburg, in addition to posing an insurmountable problem for low-lying island states where there is nowhere else for their populations to go.

Scientists said yesterday that the base of the West Antarctic Ice Sheet, which sits on rock beneath sea level, is being undermined by warmer sea temperatures that could accelerate melting and lead to higher-than-expected global sea levels.

The Scientific Committee on Antarctic Research said that the latest assessment of climate change in the southernmost continent suggests that the West Antarctic Ice Sheet is more susceptibile to disintegrating as a result of rising temperatures in the surrounding southern ocean than was previously thought.