In The Field

Sea level rise: Linear or not?

Global sea levels could rise by up to 1.5 metres by the end of the century, Svetlana Jevrejeva of the Proudman Oceanographic Laboratory in Liverpool told the EGU this morning.

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 sheet’s, such as Greenland’s.

Interestingly, Jevrejeva arrives at an even higher range (0.8 to 1.5 metres) than had Stefan Rahmstorf, an oceanographer at the Potsdam Institute of Climate Impact Research, just prior to the release of the 2007 IPCC report . Using a similar semi-empirical approach, but assuming a linear relationship between temperature and sea level change, Rahmstorf projected sea level rise in 2100 of 0.5 to 1.4 meters above the 1990 level. In a technical comment published in Science, Jevrejeva and others criticized his approach for “not meaningfully” contributing to quantifying uncertainties in the prediction of future sea-level rise.

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.


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