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Saturday 16 December 2017
16 December 2017 - NEWS UPDATE
Climate Change

Melting Arctic ice could cause $60 trillion global economic catastrophe

A giant methane burp in the Arctic could cost the world's economy a colossal $60 trillion. Billions of tonnes of the greenhouse gas methane are trapped just below the surface of the East Siberian Arctic shelf and could be released by global warming.

ArcticIceJuly24

Map showing (in white) the ice extent in July 2013; the orange line is the median extent 1981-2010. The UK is lower left of the illustration.

When the ice melts the area will be the scene of a giant gaseous belch which could bring global warming forward 35 years and cost the equivalent of almost a year's global GDP, according to new research.

Environmental economist Chris Hope and Arctic Ocean specialist Peter Wadhams, both at the University of Cambridge, together with climate policy analyst Gail Whiteman of Erasmus University in Rotterdam, the Netherlands, have analysed the likely consequences of such a release occurring between 2015 and 2025.

They did so by adding the extra emissions to an existing model used in the UK government's 2006 Stern Review, designed to assess the economic cost of coping with climate change between now and 2200.

The team calculated that a release of 50 billion tonnes would be possible within a decade, through known areas of melting and geological faults.

Because methane is a greenhouse gas 25 times as potent as carbon dioxide, such a scenario would trigger a "climate catastrophe", they say, increasing the methane content of the planet's atmosphere twelve-fold, and raising temperatures by 1.3 ˚C.

"The global impact of a warming Arctic is an economic time bomb," says Whiteman. A release of 50 billion tonnes of methane would bring forward by 15 to 35 years the date at which global temperature rise exceeds 2 ˚C above pre-industrial levels, the model shows, with most of the damage in the poorer parts of Africa, Asia and South America.

The largest costs envisaged include loss of crops to heat and drought, coping with sea level rise and worsening tropical storms.

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.

"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," said Prof Peter Wadhams.

The conclusions temper the current view of Governments and industry which expect the widespread warming of the Arctic region in the past 20 years to create an economic boom, allowing the exploitation of new gas and oilfields and enabling shipping to travel faster between Europe and Asia and increase fishing.

Previous work has estimated that more than a trillion tonnes of methane lie under the shelf, trapped inside the ice at depths as shallow as 20 metres.

Concern has grown since 2010, when research by Natalia Shakhova and Igor Semiletov, both now at the University of Alaska at Fairbanks, found plumes of methane as much as a kilometre wide rising from the surface.

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 sq km 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.

According to the National Snow and Ice Data Center (http://nsidc.org) while the rate of Arctic sea ice loss is normally fastest during July, the warmest month of the year, ice loss was even faster than usual over the first two weeks of July 2013.

As a result, on July 15 extent came within 540,000 square kilometres (208,000 square miles) of that seen in 2012 on the same date. The ice loss is dominated by retreat on the Atlantic side of the Arctic, including the East Greenland, Kara and Laptev seas, and Baffin Bay. In the Beaufort and Chukchi seas and much of the Eurasian coast, the ice cover remains fairly extensive, especially compared to recent summers. Compared to the 1981 to 2010 average, ice extent on July 15, 2013 was 1.06 million square kilometres (409,000 square miles) below average.

Article source: Journal Reference: Nature, vol. 499, p 410

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