The scientific consensus that melting ice in Greenland will contribute to a five centimetre sea-level rise this century is outdated, with the actual figure “more likely” to reach 14cm, says Dr Jan-Gunnar Winther, director of the Norwegian Polar Institute, in an interview with EURACTIV.
Winther’s declarations come as a major international summit is underway in Copenhagen to decide on a successor to the Kyoto Protocol on climate change.
The United Nation’s fourth assessment report on the science of global warming, published in 2007, had projected that sea levels could rise by 18cm to 59cm by 2099. But Winther says the report has probably been too optimistic.
“When the IPCC reported in 2007, it said there would be approximately a 5cm sea-level rise resulting from Greenland ice melt by the end of this century,” said Winther.
“Now, the research done after that indicates that it could be three times higher as the ice flows faster in Greenland, delivering icebergs to the ocean. So it is more likely that we will get a 14cm sea-level rise this century from Greenland ice melt.”
According to the Norwegian Polar Institute, this could result in central parts of the Arctic Ocean being completely ice-free twenty years from now. Should this prove to be the case, it would be the first time it has happened for 14-15 million years, it says.
More worrying still are the latest signs coming from Antarctica, Winther says. “For a long time we have thought that Antarctica would in fact increase in mass because high temperatures give more precipitation and when it is very cold, that transforms into ice or snow.”
“But then in the last ten years, we had losses around the coastal areas that have been quite rapid and dramatic. And a more recent survey from this year indicates that we have a net loss of ice from Antarctica.”
Winther’s declarations come amid unprecedented controversy around the science of global warming, with e-mail exchanges between scientists at the centre of a media furore, since dubbed ‘climategate’.
In the e-mails, scientists at the University of East Anglia’s Climatic Research Unit in Britain appear to be downplaying studies that could contradict global warming claims. The scientists sit on the Intergovernmental Panel on Climate Change (IPCC), a UN body in charge of drawing up a consensus on global warming science.
The timing of the release has cast a shadow over the conference’s chances of success, but also triggered angry reactions from prominent climate scientists who have linked the timing of the release with lobbies interested in delaying a deal.
No point of no return
Generally, the IPCC and the European Union have accepted that global warming should be kept below 2°C, the level above which climate change is expected to spiral out of control.
But the range of accepted scientific projections on global temperature rises may have to be revised, Winther suggests. In its 2007 report, the IPCC estimated that that there would be a 1.5 to 6°C temperature change by the end of the century.
“That is a wide range and it is way different if you get one or the other,” says Winther.
Surprisingly, the latest scientific findings may not necessarily paint a bleak picture, Winther suggests, saying: “It is more and more likely that we will end up around +2°C or +3°C this century,” a level above the minimum mentioned in the IPCC report but below the upper value of 6°C.
And according to Winther, there is not a point of no return as some have suggested. At least, he says he “doesn’t see it like that”.
“It is not too late, the situation is not black and white,” Winther said. “But the longer we wait, the steeper the temperatures will continue to increase and the consequences should be larger. So it is important to act rapidly but there is no such thing as an absolute limit where you have to act or not.”
‘Not Copenhagen or nothing’
On the Copenhagen meeting, Winther says there is enough scientific data on the table for politicians to make an informed decision. But he also says he understands that complex politics may delay decisions.
“I would hope for a very good agreement in Copenhagen. And I am a realist too, not only a scientist.”
“But if, for many reasons, that is not possible – and I understand that this is a very complex issue politically-speaking – I think we should not be too depressed because we have to work continuously to find this good agreement. And that should happen and needs to happen quickly.”
“I think getting a good agreement is better than getting a not so good agreement. But it is not like it is Copenhagen or nothing.”