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They examined a scenario in which there is a release of methane over a decade as global temperatures rise at their current pace.

They also looked at lower and slower releases, yet all produced “steep” economic costs stemming from physical changes to the Arctic.

“The global impact of a warming Arctic is an economic time-bomb,” said Gail Whiteman, an author of the report and professor of sustainability, management and climate change at the Rotterdam School of Management, part of Erasmus University.

“In the absence of climate-change mitigation measures, the model calculates that it would increase mean global climate impacts by $60 trillion,” said Chris Hope, a reader in policy modelling at the Cambridge Judge Business School, part of the University of Cambridge.

That approaches the value of the global economy, which was around US$70-trillion last year.

The costs could be even greater if other factors such as ocean acidification were included, the study said, or reduced to some US$37-trillion if action is taken to lower emissions.

As much as 80% of the costs would likely be borne by developing countries experiencing more extreme weather, flooding, droughts and poorer health as the Arctic melt affects the global climate, the paper said.

Methane is a greenhouse gas usually trapped as methane hydrate in sediment beneath the seabed. As temperatures rise, the hydrate breaks down and methane is released from the seabed, mostly dissolving into the seawater.