Climate scientists say a rise in sea levels due to global warming could be much higher than previously forecast.
The projection is based on new satellite studies and measurements in Greenland and Antarctica.
At an international congress on climate change in Copenhagen, Professor Stefan Rahmstorf of Potsdam said a rise in the sea level "may well exceed one metre by 2100."
A UN panel on climate change in 2007 predicted global warming would cause sea levels to rise by 18cm to 59cm this century.
The IPCC said at the time the estimate could not accurately take into account factors such as the melting of ice sheets in Greenland and Antarctica.
University of Colorado researcher Konrad Steffen said ice loss in Greenland showed an acceleration during the last decade.