Arctic ice melt an 'economic time bomb'

Rapid thawing of the Arctic could trigger a catastrophic "economic time bomb" 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 US$60 trillion (HK$465 trillion) 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, according to the study published in the journal Nature.

The Arctic sea ice, which largely melts and reforms each year, is declining at an unprecedented rate. In 2013, it collapsed to under 3.5 million square kilometres by mid September, just 40 per cent of its usual extent in the 1970s. Because the ice is also losing its thickness, some scientists expect the Arctic 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, could be emitted, either slowly over 50 years or catastrophically fast over a shorter period, 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.