Rapid warming of the Arctic could result in economic costs of $60 trillion – roughly the size of the entire world economy last year – according to a new analysis.
Writing in the journal Nature, Gail Whiteman of Erasmus University in the Netherlands, and Chris Hope and Peter Wadhams of the University of Cambridge, note that while Arctic climate change is acknowledged to carry negative environmental repercussions – particularly for sea ice-dependent life such as ringed seals and polar bears – the economic consequences have mostly been framed as positive. For example, reductions in sea ice have prompted renewed interest in using the Northern Sea Route above Russia, or the Northwest Passage through Canada's Arctic Archipelago, as swifter and cheaper trade routes than those presently used.
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But Whiteman, Hope and Wadhams argue that the economic costs of a melting Arctic will greatly exceed any benefits, with much of the cost being "borne by developing countries, which will face extreme weather, poorer health and lower agricultural production as Arctic warming affects climate."
Of particular significance, they write, is the potential for release of methane into the atmosphere as temperatures increase. Although the atmospheric duration of methane is shorter than that of carbon dioxide, it is a more potent greenhouse gas; there have long been concerns about what might happen should warming trigger the release of methane from its stores in permafrost and the seabed – and as the Nature authors remind us, there is a particularly large source beneath the East Siberian Sea:
As the amount of Arctic sea ice declines at an unprecedented rate, the thawing of offshore permafrost releases methane. A 50-gigatonne (Gt) reservoir of methane, stored in the form of hydrates, exists on the East Siberian Arctic Shelf. It is likely to be emitted as the seabed warms, either steadily over 50 years or suddenly. Higher methane concentrations in the atmosphere will accelerate global warming and hasten local changes in the Arctic, speeding up sea-ice retreat, reducing the reflection of solar energy and accelerating the melting of the Greenland ice sheet. The ramifications will be felt far from the poles.
It does not automatically follow, of course, that this methane will in fact actually be released over such a time period. While not discounting the concerns, several scientists have argued that the ten-year timeline is far too short, prompting Wadhams to defend the scenario. NASA's Gavin Schmidt is among those who have been particularly critical of the notion of such a rapid methane pulse.
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Using an updated version of a model first used in the UK government's 2006 Stern Review on the Economics of Climate Change, the authors superpose a decade-long pulse of 50 Gt of methane, released into the atmosphere between 2015 and 2025, on two standard emissions scenarios: "business-as-usual," in which emission of CO2 and other greenhouse gases continues without mitigation; and a "low-emissions" case, in which there is a 50 percent chance of keeping the rise in global mean temperatures below 2 degrees Celsius (3.6 F).
They conclude that such a methane pulse would bring forward by "15–35 years the average date at which the global mean temperature rise exceeds 2°C above pre-industrial levels - to 2035 for the business-as-usual scenario and to 2040 for the low-emissions case. This will lead to an extra $60 trillion (net present value) of mean climate-change impacts for the scenario with no mitigation, or 15% of the mean total predicted cost of climate-change impacts (about $400 trillion)."
The impacts would be felt around the globe, they write, but about 80 percent of them "will occur in the poorer economies of Africa, Asia and South America. The extra methane magnifies flooding of low-lying areas, extreme heat stress, droughts and storms."
Furthermore, their cost calculation considers only a methane pulse; adding in other consequences of a warming Arctic – including, for example, ocean acidification and altered ocean and atmospheric circulation – would drive the costs higher still.
Permafrost region in Svalbard. Photograph by Olafur Ingolfsson/NASA Earth Observatory