Sea level set to rise by one metre over next century, scientists warn
The sea level could rise by a metre over the next century, according to new research by European scientists. Their study, published in the journal Climate Dynamics, suggests that even if the temperature only rises by 2°C over the next 100 years (which is a relatively optimistic scenario), sea levels will still rise by around 80 cm. 'Basically we need to adapt to sea-level rise,' stated Dr Aslak Grinsted, a geophysicist at the University of Copenhagen in Denmark. 'CO2 reductions will help but we are already committed to a considerable rise in sea level. There is simply too much inertia in the system.' These latest predictions of sea-level rise over the next century are much greater than those published by the Intergovernmental Panel on Climate Change (IPCC). In its most recent report, it predicted that sea levels would rise by between 18 and 59 cm over the next century. The IPCC itself has admitted this is probably an underestimate. While the contributions of small glaciers and the thermal expansion of the oceans to sea level rise are quite well understood, the same cannot be said for the large ice sheets that cover Greenland and Antarctica. In this latest study, the scientists used another approach, going back in time to investigate the relationship between temperature and sea-level rise over the past 2,000 years. 'Instead of making calculations based on what one believes will happen with the melting of the ice sheets we have made calculations based on what has actually happened in the past,' explained Dr Grinsted. Data on past temperatures came from ice core borings and the annual growth rings of trees. Sea levels have been measured directly at various locations around the world for some 300 years, and other information on sea levels stretching further back in time is also available. According to the team's calculations, if the temperature rises by 3°C over the next 100 years, sea levels will rise by between 0.9 and 1.3 metres. A more optimistic scenario, involving a temperature rise of 2°C, will lead to a sea-level rise of around 80 cm. Meanwhile, under a more pessimistic scenario, with a temperature rise of 4.5°C the sea level could rise by as much as 1.35 metres. 'Even if we stop the temperature from rising, the sea level will still rise by 20 to 40 cm,' said Dr Grinsted. 'To stop sea levels from rising, we should lower temperatures by 0.6°C.' The researchers note that the sea level will rise faster during the 21st century than at any other time in the past 2,000 years. Nevertheless, such rapid changes in the sea level are not without precedent; at the end of the last ice age, some 11,700 years ago, the ice sheets melted so fast that the sea level rose by 11 millimetres a year - equivalent to over a metre in 100 years. 'All experts knew that the IPCC projects were too conservative, including the IPCC themselves, and those I talked to had a feeling that something like 1 to 1.5 metres of rise was to be expected,' commented Dr Grinsted. 'Now we provide some good solid evidence. Hopefully infrastructure planners will listen and plan accordingly.'
Countries
Denmark, Finland, United Kingdom