Forecast for big sea level rise

Today's "uh oh," by Richard Black, environment correspondent for the BBC: Sea levels could rise by up to one-and-a-half metres by the end of this century, according to a new scientific analysis. This is substantially more than the Intergovernmental Panel on Climate Change (IPCC) forecast in last year's landmark assessment of climate science. Sea level rise of this magnitude would have major impacts on low-lying countries such as Bangladesh.

The findings were presented at a major science conference in Vienna. The research group is not the first to suggest that the IPCC's forecast of an average rise in global sea levels of 28-43cm by 2100 is too conservative. The IPCC was unable to include the contribution from "accelerated" melting of polar ice sheets as water temperatures warm because the processes involved were not yet understood.

The new analysis comes from a UK/Finnish team which has built a computer model linking temperatures to sea levels for the last two millennia. "For the past 2,000 years, the [global average] sea level was very stable, it only varied by about 20cm," said Svetlana Jevrejeva from the Proudman Oceanographic Laboratory (POL), near Liverpool, UK. "But by the end of the century, we predict it will rise by between 0.8m and 1.5m. The rapid rise in the coming years is associated with the rapid melting of ice sheets."

The model, she told reporters here at the European Geosciences Union (EGU) annual meeting, is able to mimic accurately sea levels reliably observed by tide gauges over the last 300 years. There is little concrete evidence on sea levels for the thousands of years before that, explained POL's Simon Holgate, who was not involved in the new study….

Margin of the Greenland ice sheet, seen from a plane. Photo by Hannes Grobe, Alfred Wegener Institute for Polar and Marine Research, from Wikimedia Commons, licensed under the Creative Commons Attribution ShareAlike 2.5 License.