Geophys. Res. Lett. doi:10.1029/2007GL032486 (2008)

Credit: SHAHEE ILYAS

The extent to which sea level could rise by 2100 is greatly underestimated in current models, suggests a new study, highlighting the risk faced by coastal areas and island nations.

Radley Horton at Columbia University, US, and colleagues estimated that sea level could rise by 54 to 89 centimetres by the end of the century, in contrast to the latest estimate by the Intergovernmental Panel on Climate Change (IPCC) of 18 to 59 centimetres. The team used a different approach to directly estimate rates of sea-level rise on the basis of model projections of ground surface temperature changes. The future sea-level rise predicted was mostly determined by the assumed rate of greenhouse gas emissions, suggesting that changes in emissions will be the main determinant of sea-level rise in the twenty-first century.

Neither these estimates nor those of the latest IPCC report take into account the recent acceleration of ice loss in the Greenland and West Antarctic Ice Sheets or the indirect effects of loss of Arctic sea ice cover, however. The scientists point out that current projections could therefore strongly underestimate the magnitude of sea-level rise in the coming century if ice loss continues to accelerate in polar regions.