Ever Heard of a "Methane Pulse"? Get Ready, It Could be Just Two Years Away.

It's sort of like walking along a cliff edge blindfolded.   Most of us, given the choice, would say no.

There's a worst case scenario and a best case scenario and not much in between.  That's the situation that confronts us with new warnings that we could be taken by surprise by a "methane pulse" from the Arctic.  Put simply we may be at a major tipping point, the loss of Arctic sea ice, that triggers a natural feedback mechanism giving rise to runaway global warming.

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.

Read The Guardian's interview with Professor Wadhams here.

When you think this through, there are only a couple of possibilities.   One, Wadham's right.  If he's right it's hard to imagine what we can do about this threat at this late stage.   The effective tipping point, that point at which we must take action to prevent the canoe from rolling over, has passed.  Or there's number Two, Wadham's wrong.   We might have decades before this occurs, possibly centuries.

The thing is, we need to know whether Wadham's right or, if not, how far off the mark he actually is.   We know that the Arctic climate has already undergone substantial change over just the past five to ten years.   We know the changes already in effect are accelerating further change.   We know these changes are wide-reaching, impacting most of the northern hemisphere and sometimes beyond.

The tangible and powerful changes we have already seen, researched and recorded mean that we don't get to dismiss warnings from Professor Wadhams as "alarmist".  The clock has run out on that ploy.  We need answers and the Harper government owes us that much - and a good deal more.