The world’s seas could rise far faster than the UN is predicting, according to research presented to this week’s European Geosciences Union meeting. If this work is right, millions of people are living on what will soon be sea floor.

Svetlana Jevrejeva, from the UK’s Proudman Oceanographic Laboratory, thinks we could see rises of 1 to 1.5 metres by 2100. By contrast the UN’s Intergovernmental Panel on Climate Change has predicted only a 28 to 43 cm rise by 2100.

Nature’s Quirin Schiermeier is blogging the conference at In the Field*:

Jevrejeva and her team reconstructed seal levels for the past 2,000 years, and then used a non- linear equation relating sea levels to temperature change to predict future sea level rise. Unlike the Intergovernmental Panel for Climate Change (IPCC), whose most recent prediction of sea level rise is three times smaller, the team incorporated into their prediction the rapid response to global warming of large ice sheets, such as Greenland’s.

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The global sea level currently rises by 3.5 millimetres per year, as the combined result of thermal expansion of ocean water, glacier melting, and changes in the global hydrological cycle. Sea level rise by 1.5 meters would result in the loss of most of Bangladesh, and threaten low-lying regions around the world. In China alone, some 100 million people would need to be displaced if sea level were to rise by one meter or more.

The BBC notes that Jevrejeva’s results have been submitted for publication in PNAS. Both the BBC and Reuters quote Steve Nerem, from the University of Colorado, saying: “There’s a lot of evidence out there that we’re going to see at least a metre of sea level rise by 2100,” says

Climate modeller/blogger William Connolley isn’t convinced. On his blog, under the headline Don’t believe a word of it, guv, he says:

… it’s rather unclear where 0.8-1.5m comes from or how you can get that from monitoring past changes. Extrapolating past change into the future won’t get you more than 0.3m for the 21st century.

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Oh, and when I say I don’t believe in 1.5m this century… I don’t rule it out as impossible; but I can’t see how you can get it from this stuff. … Apparently “The rapid rise in the coming years is associated with the rapid melting of ice sheets.” I think its entirely likely that *if* SLR is much larger than IPCC projections then the excess will come from ice sheets. But how you get that from past data is murky.

*Along with Oliver Heffernan of Nature Reports Climate Change.

Image: Getty