UPDATE: It is always a good thing to actually read the paper rather than just use a media report. It appears there are some interesting problems with the paper, as mentioned by Andy Revkin.
Ice-free Arctic in two years heralds methane catastrophe – scientist
[Via Science news, comment and analysis | guardian.co.uk]
Professor Peter Wadhams, co-author of new Nature paper on costs of Arctic warming, explains the danger of inaction
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:
This study is all over the media, what with its $60 trillion prediction of the economic cost of this methane release. Their number may be right but the unknown thing is over what time-frame this might happen in. Over a century might not be so bad. In 10 years would be horrible.
I’ve written about a lot of similar reports over the last few years: Methane from thawing permafrost could be a big tipping point; The release of methane causes extinction events; Increasing amounts of natural methane emissions; Warming bigtime up north.
One of the points Wadhams mentions is that climate models are based on certain facts, facts that are well known and provide the parameters for the future prediction. But, many models have actually made forecasts in thewrong direction, at least when it comes to feeling sanguine about the future.
As the article mentions, models predict an ice free arctic in 40 years. Yet, extrapolation of ongoing data indicate that the Arctic might be ice-free before the end of this decade. This means that the models underestimated the effects of global warming. What happens if the Arctic becomes free of ice much faster than most models predict?
That is worrisome and why, even if viewed with skepticism, we should look carefully at Wadhams work. He attempts to use specific empirical data in his hypothesis, using trend analysis. If the trends indicate that Arctic ice will be gone within a decade, he uses that. Most climate models to not really include such trends in their analysis. Their models also look at the world with a crude scale due to computational needs. Some processes may require a much finer grid to actually see properly.
He is right on one thing – the data do not match the models in some areas, such as the Arctic. And in almost every case, the models underestimate the effects of global warming. That is to be expected as most scientists are cautious and would rather undershoot the mark than overshoot it.
But Wadhams work suggests that this caution may be keeping us from the truth. The Arctic will warm more than any other part of the globe due to climate change. So the effects there really should be examined with a very fine grid.