Current sea level rise projections could be under-estimating the impact of human-induced climate change on the world's oceans, scientists suggest.
By plotting global mean surface temperatures against sea level rise, the team found that levels could rise by 59% more than current forecasts.
The researchers say the possibility of greater increases needs be taken into account when planning coastal defences.
The findings have been published in the online edition of the journal Science.
The team from Germany and the US found that for the timescale relevant to human-induced climate change, the observed rate of sea level rise through the 20th Century held a strong correlation with the rate of warming.
When applied to the possible scenarios outlined by the Intergovernmental Panel on Climate Change (IPCC), the researchers found that in 2100 sea levels would be 0.5-1.4m above 1990 levels.
This projection is much greater than the 9-88cm forecast made by the IPCC itself in its Third Assessment Report, published in 2001.
He writes in Science Express: "Understanding global sea level changes is a difficult physical problem, as a number of complex mechanisms with different timescales play a role."
* thermal expansion of water through heat absorption
* water entering the oceans from glaciers and ice sheets
* increased ice flows after the removal of buttressing ice shelves
Professor Rahmstorf said he decided to use observational data because computer models of climate significantly under-estimated the sea level rise that had already occurred.
"The fact that we get such differences using different methods shows how uncertain our sea level forecasts still are," he said.
Greenland's glaciers have been sliding faster towards the sea
He added that the main uncertainty was the response of large ice sheets in Greenland and Antarctica to rising temperatures, which was difficult to predict.
Saturday, December 16, 2006
Sea level rise 'under-estimated'
I'm definitely seeing a pattern with the reporting on climate change stories. Seems that with every single story on every new report it is always we underestimated the effects or this particular effect is happening much sooner than we thought it would. The BBC reports that Sea level rise 'under-estimated':