WE NOW have a clearer idea of what is happening to the ice in Greenland and Antarctica, and it means rising sea level may drown the official estimates. That鈥檚 the warning from a , this week.
In 2007, the Intergovernmental Panel on Climate Change forecast a rise of 18 to 59 centimetres by 2100. But these figures did not include water from the Greenland and Antarctic ice sheets because models of future melting were deemed inconclusive. Yet Greenland alone holds enough water to raise sea level by 6 metres on average worldwide.
Recent measurements show that sea level has been rising by 3 millimetres a year since 1993, which exceeds IPCC forecasts. Not surprisingly, it seems Greenland and Antarctica are to blame. 鈥淭he ice sheets are already contributing more and faster to sea level rise than anticipated鈥� due to the acceleration of the glaciers flowing from them, says Eric Rignot of the University of California in Irvine and NASA鈥檚 Jet Propulsion Laboratory in Pasadena, California. 鈥淚f this trend continues, we are likely to witness sea level rise by 1 metre or more by 2100,鈥� he says.
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A rise of only half a metre would be bad enough, says John Church of the Centre for Australian Weather and Climate Research. He has shown that in Australia, such a rise would cause 鈥渉undred year鈥� flooding events to occur several times a year by 2100.