Sea levels could rise far more rapidly than expected in coming decades according to new research that reveals Antarctica’s vast ice cap is less stable than previously thought.
The UN’s climate science body had predicted up to a metre of sea level rise this century – but it did not anticipate any significant contribution from Antarctica where increasing snowfall was expected to keep the ice sheet in balance.
According a study published in the journal Nature collapsing Antarctic ice sheets are expected to double sea-level rise to two metres by 2100 if carbon emissions are not cut.
Previously only the passive melting of Antarctic ice by warmer air and seawater was considered but the new work added active processes – such as the disintegration of huge ice cliffs.
‘This [doubling] could spell disaster for many low-lying cities’ said Prof Robert DeConto at the University of Massachusetts Amherst who led the work.
He said that if global warming was not halted the rate of sea-level rise would change from millimetres per year to centimetres a year.
‘At that point it becomes about retreat [from cities] – not engineering of defences’.
As well as rising seas, climate change is also causing storms to become fiercer – forming a highly destructive combination for low-lying cities like New York, Mumbai and Guangzhou.
But the new work suggests that major rises are possible within the lifetimes of today’s children – not over centuries.