Ice-free Arctic in two years heralds methane catastrophe: Interview with polar ocean physicist Peter WadhamsPosted by Jim at Friday, July 26, 2013
By Nafeez Ahmed
24 July 2013
(The Guardian) – A new paper in the journal Nature argues that the release of a 50 Gigatonne (Gt) methane pulse from thawing Arctic permafrost could destabilise the climate system and trigger costs as high as the value of the entire world's GDP. The East Siberian Arctic Shelf's (ESAS) reservoir of methane gas hydrates could be released slowly over 50 years or "catastrophically fast" in a matter of decades – if not even one decade – the researchers said.
Not everyone agrees that the paper's scenario of a catastrophic and imminent methane release is plausible. NASA's Gavin Schmidt has previously argued that the danger of such a methane release is low, whereas scientists like Prof Tim Lenton from Exeter University who specialises in climate tipping points, says the process would take thousands if not tens of thousands of years, let alone a decade.
But do most models underestimate the problem? A new paper in Proceedings of the National Academy of Sciences (PNAS) projects that the Arctic will be ice free in September by around 2054-58. This, however, departs significantly from empirical observations of the rapid loss of Arctic summer sea ice which is heading for disappearance within two or three years according to Nature co-author and renowned Arctic expert Prof Peter Wadhams, head of the Polar ocean physics group at Cambridge University.
If Prof Wadhams is correct in his forecast that the summer sea ice could be gone by 2015, then we might be closer to the tipping point than we realise. To get to the bottom of the scientific basis for the Nature paper's scenarios, I interviewed Prof Wadhams. Here's what he had to say:
How long do we have before the Arctic summer sea ice disappears?
Given present trends in extent and thickness, the ice in September will be gone in a very short while, perhaps by 2015. In subsequent years, the ice-free window will widen, to 2-3 months, then 4-5 months etc, and the trends suggest that within 20 years time we may have six ice-free months per year. [more]