See our interactive map of regional sea-level rises
SYDNEY, Tokyo and Buenos Aires watch out. These cities will experience some of the greatest sea level rises by 2100, according to one of the most comprehensive predictions to date.
Sea levels have been rising for over 100 years - not evenly, though. Several processes are at work, says Mahé Perrette of the Potsdam Institute for Climate Impact Research in Germany. Some land is sinking, some is rising. Stronger currents create slopes in sea surface, and since all things with mass exert a gravitation pull, disappearing ice sheets lead to a fall in sea levels in their surrounding areas.
Perrette has modelled all of these effects and calculated local sea level rises in 2100 for the entire planet. While the global average rise is predicted to be between 30 and 106 centimetres, he says tropical seas will rise 10 or 20 per cent more, while polar seas will see a below-average rise. Coasts around the Indian Ocean will be hard hit, as will Japan, south-east Australia and Argentina (Earth System Dynamics, doi.org/kbf).
New York's position may be less perilous than previously thought. A weakening of the Atlantic Gulf Stream will cause water to slop westwards, triggering a rapid rise on the eastern seaboard, but this will be counteracted by Greenland's weaker gravitational pull. The city is not out of the woods, though, warns Aimée Slangen of Utrecht University in the Netherlands, whose own model suggests that Antarctica could lose a lot of ice, which would produce an above-average rise throughout the northern hemisphere.
For now, Perrette offers a warning to tropical countries. "You may have 120 centimetres of sea level rise on your coastline," he says. "Build defences."
This article appeared in print under the headline "Where not to be when seas rise up to meet us"
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New map pinpoints cities to avoid as sea levels rise
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New map pinpoints cities to avoid as sea levels rise
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New map pinpoints cities to avoid as sea levels rise
