How much will the sea rise ?

New Scientist (March 14, 2009) reports that the estimates or rising sea level provided by the Intergovernmental Panel on Climate Change which forecast a rise of 18 to 59 centimetres by 2100 are too low. The estimates did not include water from the Greenland and Antartica ice sheets and Greenland alone has enough ice which if melted would raise sea levels by 6 metres on average, worldwide. The most recent measurements show sea level has been rising 3 millimetres a year since 1993.

This is not good news as the altered estimates would bring forward the dates by which low level land and island groups would experience permanent water inundation. The difficulty with all these estimates is the lack of clear models which encompass a rigorous methodology including all known ice sources which can melt and feed directly into sea levels.