Sea level rose 60 percent faster than UN projections, study finds

http://worldnews.nbcnews.com/_news/2012/11/28/15512957-sea-level-rose-60-percent-faster-than-un-projections-study-finds?lite

Nov. 28, 2012
By Miguel Llanos, NBC News

Projections for sea level rise in coming decades could be too conservative, experts warned Wednesday, saying they found that the rise over the last two decades is much more than predicted by the U.N. scientific body tracking climate signals.

In a peer-reviewed study, the experts said satellite data show sea levels rose by 3.2 millimeters (0.1 inch) a year from 1993 to 2011 — 60 percent faster than the 2 mm annual rise projected by the U.N.'s Intergovernmental Panel on Climate Change for that period.

"This suggests that IPCC sea-level projections for the future may also be biased low," the team wrote in the journal Environmental Research Letters.

The experts also said the IPCC was just about spot on with its predictions for warming temperatures.

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The IPCC earlier estimated that seas rose by about 7 inches over the last century, and its most recent report, published in 2007, estimated a range of between 7 and 23 inches this century — enough to worsen coastal flooding and erosion during storm surges.

But the IPCC report did not factor in a possible acceleration of the melt of the Greenland and Antarctic ice sheets.

The IPCC "assumed that Antarctica will gain enough (ice) mass" to compensate for Greenland ice loss, the new study's authors noted, but more recent studies have shown that "the ice sheets in Greenland and Antarctica are increasingly losing mass."

Rahmstorf told Reuters his best estimate for sea level rise was between 20 inches and three feet this century, possibly more if greenhouse gas emissions of carbon dioxide surged.

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The results confirm that global warming, which was predicted by scientists in the 1960s and 1970s as a consequence of increasing greenhouse concentrations, continues unabated at a rate of 0.16 °C per decade and follows IPCC projections closely.