It's the most urgent call for geoengineering yet: begin cooling the Arctic by 2013 or face runaway global warming. But the warning – from a voice on the scientific fringe – may be premature, according to experts contacted by New Scientist.
John Nissen, a former software engineer who has become alarmed at the possibility of reaching a climate "tipping point" argued for Arctic geoengineering as soon as possible in a poster presentation at the American Geophysical Union meeting in San Francisco last week.
"We've got to pull out all the stops to prevent a runaway situation," Nissen says. He suggests using stratospheric aerosols to cool the surface and subsurface below, or increasing the reflectance of low-level clouds by pumping a fine spray of salt water into them.
Although Nissen's opinion is not in the scientific mainstream, he has the backing of a leading expert on sea ice, Peter Wadhams of the University of Cambridge, who recently suggested that the Arctic ocean may be ice-free at the end of each summer from 2015 onwards. Wadhams says that accelerating climate change in the Arctic has forced him to abandon his scepticism about geoengineering. "One has to consider doing something," he says.