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.

Why do the climate models not match empirical observations – and why is your estimate of the Arctic sea ice disappearance so different from most model projections?

The modellers did not pay sufficient regard to observations, especially of ice thickness. They considered certain physical processes in the model, then when the rate of retreat greatly outstripped the predictions of the model, they ignored the observations and stuck with the model. A very great physicist, Richard Feynmann, said that when a model comes up against measurements that contradict it, it is the measurements that must be preferred and the model must be abandoned or changed. Scientists who have a lot of their credibility bound up in a model are reluctant to do this. Then there are a number of key processes that can only be represented if the model has a very fine grid scale, such effects as the break-up of ice due to waves generated in the large areas of open water that we now have in summer; or the additional weakening of the ice by meltwater pools that melt their way right through the ice sheet. A modeller who represents all these fine scale processes is Wiselaw Maslowsky (Monterey) and his models agree with my empirical predictions.

Our global emissions trajectory is already on track to breach 2C in coming decades. What does a 2C world imply for the Arctic melt and the potential for methane release?

We are already in a 2C world in terms of the heating potential of carbon dioxide that we have already put into the atmosphere. The heating will reach 2C before 2050 and will then go on to 3-4C globally by the end of the century. Even a 2C world involves the probable loss of Arctic sea ice for much of the year (and 4C for most of it), which will ensure maximum methane release from the exposed shallow seas of the continental shelves.

What does the loss of the Arctic summer sea ice mean for the climate? How will this impact on society and the economy?

Our own model shows that the methane release from the ice retreat will add about 0.6C to global warming by 2040. Adding on the faster sea level rise, and trend towards greater extremes in weather (due to jet stream displacement) means increased risk of catastrophic floods in less developed countries and a decrease in food production at a time when world population is rapidly increasing.

What is the link between permafrost melt, methane release and the loss of the Arctic sea ice? After 2015, if the Arctic becomes ice free in the summer, is there a heightened danger of methane release?

The loss of sea ice leads to seabed warming, which leads to offshore permafrost melt , which leads to methane release, which leads to enhanced warming, which leads to even more rapid uncovering of seabed. If a large release has not occurred by 2016 the danger will be continuously increasing. It is thought that at 2-3C of global warming, which means 6-8C of Arctic warming, methane release from permafrost on land will be greatly increased.

Some people say that a catastrophic methane release over 10 years – your worst-case scenario – is a very low probability event and we don’t really need to worry about it. What’s your response to that?

Those who understand Arctic seabed geology and the oceanography of water column warming from ice retreat do not say that this is a low probability event. I think one should trust those who know about a subject rather than those who don’t. As far as I’m concerned, the experts in this area are the people who have been actively working on the seabed conditions in the East Siberian Sea in summer during the past few summers where the ice cover has disappeared and the water has warmed. The rapid disappearance of offshore permafrost through water heating is a unique phenomenon, so clearly no “expert” would have found a mechanism elsewhere to compare with this.

Would Arctic experts agree with you?

I think that most Arctic specialists would agree that this scenario is plausible.

What about scientists like Prof Tim Lenton, a climate tipping point expert, who argues that a methane release is a long-term problem, not an immediate danger?

His earlier conclusions are out of date. His oft-cited paper on tipping points is two years old now and was based on literature surveys rather than direct research. An ice-free summer (September) Arctic is clearly nearly upon us, and will be achieved within three years or less – this is plain from the observational data on ice extent (satellites) and thickness (submarines and altimeter satellites). I am sure that he is about to revise his views if he hasn’t already done so.

Dr Nafeez Ahmed is executive director of the Institute for Policy Research & Development and author of A User’s Guide to the Crisis of Civilisation: And How to Save It among other books. Follow him on Twitter @nafeezahmed

Rapid thawing of the Arctic could trigger a catastrophic “economic timebomb” which would cost trillions of dollars and undermine the global financial system, say a group of economists and polar scientists.

Governments and industry have expected the widespread warming of the Arctic region in the past 20 years to be an economic boon, allowing the exploitation of new gas and oilfields and enabling shipping to travel faster between Europe and Asia. But the release of a single giant “pulse” of methane from thawing Arctic permafrost beneath the East Siberian sea “could come with a $60tn [£39tn] global price tag”, according to the researchers who have for the first time quantified the effects on the global economy.

Even the slow emission of a much smaller proportion of the vast quantities of methane locked up in the Arctic permafrost and offshore waters could trigger catastrophic climate change and “steep” economic losses, they say.

The Arctic sea ice, which largely melts and reforms each year, is declining at an unprecedented rate. In 2013, it collapsed to under 3.5m sqkm by mid September, just 40% of its usual extent in the 1970s. Because the ice is also losing its thickness, some scientists expect the Arctic ocean to be largely free of summer ice by 2020.

The growing fear is that as the ice retreats, the warming of the sea water will allow offshore permafrost to release ever greater quantities of methane. A giant reservoir of the greenhouse gas, in the form of gas hydrates on the East Siberian Arctic Shelf (ESAS), could be emitted, either slowly over 50 years or catastrophically fast over a shorter time frame, say the researchers.

The ramifications of vanishing ice will also be felt far from the poles, they say because the region is pivotal to the functioning of Earth systems, such as oceans and climate. “The imminent disappearance of the summer sea ice in the Arctic will have enormous implications for both the acceleration of climate change, and the release of methane from off-shore waters which are now able to warm up in the summer,” said Prof Peter Wadhams, head of the Polar ocean physics group at Cambridge University and one of the authors of the paper published in the journal Nature.

“This massive methane boost will have major implications for global economies and societies. Much of those costs would be borne by developing countries in the form of extreme weather, flooding and impacts on health and agricultural production,” he said.

According to the authors, who using the Stern review, calculated that 80% of the extra impacts by value will occur in the poorer economies of Africa, Asia and South America. “Inundation of low-lying areas, extreme heat stress, droughts and storms are all magnified by the extra methane emissions,” they authors write. They argue that global economic bodies have not taken into account the risks of rapid ice melt and that the only economic downside to the warming of the Arctic they have identified so far has been the possible risk of oil spills.

But, they say, economists are missing the big picture. “Neither the World Economic Forum nor the International Monetary Fund currently recognise the economic danger of Arctic change. [They must] pay much more attention to this invisible time-bomb. The impacts of just one [giant “pulse” of methane] approaches the $70-tn value of the world economy in 2012″, said Prof Gail Whiteman, at the Rotterdam School of Management and another author.

The Nature report comes as global shipping companies prepare to send a record number of vessels across the north of Russia later in 2013, slashing miles travelled between Asia and Europe by over 35% and cutting costs up to 40%.

According to Russian authorities, 218 ships from Korea, China, Japan, Norway, Germany and elsewhere have so far applied for permission to follow the “Northern sea route” (NSR) this year. This route uses the Bering Strait between Siberia and Alaska and is only open for a few months each year with an icebreaker.

But following 2012’s record collapse of the Arctic sea ice, shipping companies are gaining confidence to use the route. In 2012, only 46 ships sailed its entire length from the Atlantic to Pacific oceans and in 2011 only four. The route can save even medium-sized bulk carrier 10-15 days and hundreds of tonnes of bunker fuel on a journey between northern Norway and China.

Satellite data collated from the US National snow and ice data centre in Boulder, Colorado this week showed ice loss now accelerating and, at 8.2m sqkm (3.2m square miles) approaching the same extent as during last year’s record melt. Over 130,000 sqkm of sea ice melted between July 1 and 15. “Compared to the 1981 to 2010 average, ice extent on July 15 was 1.06m sqkm (409,000 square miles) below average,” said a spokseman.

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The release of a giant methane pulse from thawing Arctic permafrost could destabilise the climate system and trigger huge costs to the global economy within coming decades, warns a forthcoming paper in the journal Nature.

The paper highlights the link between the “unprecedented rate” of melting of Arctic sea ice, and the intensifying methane emissions from thawing offshore permafrost. The East Siberian Arctic Shelf (ESAS) alone carries a 50 Gigatonne (Gt) reservoir of methane gas hydrates which could be released slowly over 50 years or “catastrophically fast” in a matter of decades under the current pace of global warming.

The increasing release of methane coupled with the loss of Arctic sea ice would create an amplifying feedback “speeding up sea-ice retreat, reducing the reflection of solar energy and hastening sea-level rise as the Greenland ice sheet melt accelerates.” Recent research on ‘Arctic amplification’ has demonstrated a complex relationship between the earth system and the Arctic. The accelerating melt process is already altering the jet stream which seems to be multiplying and accentuating extreme weather events.

As I wrote in May:

“Extreme weather events over the last few years apparently driven by the accelerating Arctic melt process – including unprecedented heatwaves and droughts in the US and Russia, along with snowstorms and cold weather in northern Europe – have undermined harvests, dramatically impacting global food production and contributing to civil unrest.”

The authors of the Nature article, modelling the potential consequences of the 50 Gt East Siberian methane release over different time periods, conclude that it “will bring forward by 15–35 years the date at which the global mean temperature rise exceeds 2C above pre-industrial levels” – the ‘safe limit’ accepted by policymakers (though its safety has been disputed by leading scientists).

Under a business as usual scenario, this will generate an “extra $60 trillion (net present value) of mean climate change impacts” – nearly the same value as the entire GDP of the global economy. The lower emissions scenario (which unfortunately looks far less plausible at the moment) would “be an extra $37 trillion” – still over half of world GDP.

Two of the Nature authors are leading business school scholars – Prof Gail Whiteman at the Department of Business-Society Management, Erasmus University, and Dr Chris Hope at the Judge Business School, Cambridge University. The third author is Prof Peter Wadhams, Head of the Polar Ocean Physics Group at Cambridge.

They point out that 80% of climate change impacts will hit poorer, less developed countries through “inundation of low-lying areas, extreme heat stress, droughts and storms”, all of which will be “magnified by the extra methane emissions.” But they also emphasise that their analysis only focuses on potential impacts from “one feedback” involving methane release from the ESAS, and is therefore probably “conservative” – implying actual costs could be much higher. They warn of an urgent need to:

“… re-direct economic attention from short-term economic gains from shipping and extraction to what appears to be an economic time-bomb… The costs of Arctic change carry significant – yet thus far invisible – risks to our global economic foundations.”

The authors urge the World Economic Forum, the International Monetary Fund, and other financial institutions to embark on new research accounting for such dramatic costs of Arctic climate change, which so far have been insufficiently recognised.

Current models do not incorporate amplifying feedbacks such as “linking the extent of Arctic ice to increases in Arctic mean temperature, global sea level rise and ocean acidification”; nor do they include critical “feedback loops”, such as “the effects of black carbon deposits from forest and agricultural fires, diesel use and industrial activity on snow and ice reflectivity and melting”, as well as links between Arctic sea ice extent, global sea level rise, increased shipping and the increase in Arctic local temperatures. Without analysing these factors, “world leaders and economists will continue to miss the big picture.”

The extent to which the majority of climate models have underplayed the scale of the challenge in the Arctic is evident from a new paper in Proceedings of the National Academy of Sciences (PNAS) which projects that the Arctic will be ice free in September by around 2054-58. The projection departs significantly, however, from actual empirical observations of the rapid loss of Arctic summer sea ice which is heading for disappearance within three years according to Nature co-author and renowned sea ice expert Prof Wadhams.

NASA airborne surveillance in the Arctic has already encountered large “plumes of methane” as much as 150 kilometres wide. While no one knows for sure how and when a significant methane release might occur, recent evidence shows that once the Arctic summer sea ice disappears the chances of breaching a tipping point in methane release from melting permafrost are far higher.

New research led by Dr Anton Vaks of Oxford University reconstructing the history of Siberian permafrost shows that continuous melting sufficient to release significant quantities of methane would begin at around 1.5C, a temperature rise to which the world is already committed early this century.

Underscoring the urgency of mitigation efforts, the Nature paper warns that it would be:

“… difficult, perhaps impossible, to avoid large methane releases in the East Siberian Sea without significant reductions in global emissions of CO2, since it is seabed warming, a product of summer sea ice retreat, which directly drives the methane release.”

If Prof Wadhams is correct in his forecast that the summer sea ice will be gone by 2016, then we could be closer to the tipping point than we realise.

Dr Nafeez Ahmed is executive director of the Institute for Policy Research & Development and author of A User’s Guide to the Crisis of Civilisation: And How to Save It among other books. Follow him on Twitter @nafeezahmed