March 10, 2009

Sea Level Rise Could Bust IPCC Estimate

"Sea level rises could bust official estimates – that's the first big message to come from the climate change congress that kicked off in Copenhagen, Denmark, today.

Researchers, including John Church of the Centre for Australian Weather and Climate Research, presented evidence that Greenland and Antarctica are losing ice fast, contributing to the annual sea-level rise. Recent data shows that waters have been rising by 3 millimetres a year since 1993.

Church says this is above any of the rates forecast by the IPCC models. By 2100, sea levels could be 1 metre or more above current levels, he says. And it looks increasingly unlikely that the rise will be much less than 50 centimetres.

In 2007, the Intergovernmental Panel on Climate Change forecast a rise of 18 cm to 59 cm by 2100. But the numbers came with a heavy caveat that often went unnoticed by the popular press.

Because modelling how the Greenland and Antarctic ice sheets will react to rising temperatures is fiendishly complicated, the IPCC did not include either in its estimate. It's no small omission: the Greenland ice cap, the smaller and so far less stable of the two, holds enough water that if it all melted, it would raise sea levels by 6 metres on average across the globe."

ORIGINAL SOURCE: New Scientist

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