Methane Released by Arctic Melting Could Cost the World $60 Trillion in Climate Extremes

The costs resulting from methane released by melting Arctic ice could equal $60 trillion, or roughly a year of global economic output, according to a paper published Wednesday in the journal Nature.

Trapped within the East Siberian Arctic Shelf is an estimated 50 gigatons of the known greenhouse gas that is expected, according to the scientists, to be released either suddenly or gradually over the next half century based on how quickly the ice melts.

Either way, the researchers, who hail from Cambridge and Erasmus Universities, argue that higher concentrations of methane 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."

In coming to these conclusions the researchers used the PAGE09 model developed to calculate the impacts of climate change and the costs of mitigation and adaption measures through assessing how the net present value of climate effects varies with each ton of carbon dioxide emitted or saved.

In order to erase as much room for error as possible and to account for multiple scenarios, the scientists ran the model 10,000 times, taking into account a variety of possible variables and comparing the various outcomes.

They superimposed several possible scenarios in regards to the release of methane, including one based on rising CO2 levels based on current trends and another that accounted for lower emissions over time.

In all of the cases, the scientists found a "steep global price tag" even after possible short-term gains as a result, for example, of the opening of shipping lanes as ice continues to melt.

Furthermore, the study determined that fully 80 percent of the economic consequences will focus on the poorer economies of Africa, Asia and South America as intense flooding, extreme heat, droughts and storms are likely to occur in each of these regions.

How quickly this process will take place is unclear, though a recent study published in the journal Proceedings of the National Academy of Sciences argues that the Arctic could experience an ice-free September by 2054.

The Nature report is not without its critics, however, one of which is Tim Lenton of Exeter University and a specialist in climatic tipping points. Speaking to the UK's Environmental Audit Committe, Lenton believes that, while methane can be problematic, the process will take place over a much longer time scale, spreading its effects across a much larger period of time.

"My personal view on this, having done some work on it and feeling I know the field reasonably well, is that, yes, methane in the long run and methane loss from these frozen reservoirs will be a long-term significant amplifier," he said, explaining that by "long-term" he means "thousands and tens of thousands of years."