Ever since the Stern Review attempted to quantify the economic cost of climate change, scientists and economists have continued to explore how planetary changes might impact the prosperity of future generations. Like much climate related research, their predictions are highly contested: any attempt to chart a future as full of unknowns and complex variables can never be precise.
But that does not make such work pointless, as some critics have tried to argue. We tend to accept apparently simpler cost comparisons of, say, renewable energy versus fossil fuels, but these also contain assumptions and exclusions that render them unreliable. Coal is routinely described as a cheap fuel, for instance, but when the water and health impacts are taken into account, let alone the climate implications, the figures look very different.
The variables of climate science itself, especially the idea of tipping points, add greatly to the difficulty of reaching reliable estimates of future economic impacts: we can project current warming trends, correlated to rising emissions, in a relatively smooth graph, but scientists warn that warming itself might trigger sudden changes that would throw the predictions off. The release of methane, a greenhouse gas 25 times more powerful than CO2, is one such wild card.
The authors of a new article in Nature this month warn that the billions of tonnes of methane currently locked into the frozen shelf of the Arctic Ocean could have devastating economic effects and accelerate climate change by decades. The team comprised experts at the Judge Business School in Cambridge and Erasmus University in the Netherlands.
As the Arctic melts, the risk of massive methane release is growing. The researchers modelled the effects of a leakage of 50 billion tonnes from the floor of the East Siberian Sea, a two million square kilometre (772,200 square mile ) sector of the Arctic Ocean off north-eastern Russia. Taken over a decade, the release of such a volume of methane would bring forward the date at which the global mean temperature rise exceeds two degrees Celsius (3.6 degrees Fahrenheit) – internationally agreed to be dangerous – by up to 35 years, and would cost the world economy $60 trillion in floods, droughts and heat stress. Up to 80% of the effects would occur in Africa, Asia and South America, according to the authors.
The likely speed of methane release is itself a variable which is affected by the rate of increase in other greenhouse gases, but whenever it happened, it would accelerate climate change and render human attempts to control it immeasurably more difficult and expensive. One way to deal with these uncertainties, as the Nobel prize winning economist George Akerlof wrote in 2006, is to insure against future threats by taking action now: it is by far the cheapest option in the long run.