They look like massive bomb craters. So far seven of these gaping chasms have been discovered in Siberia, apparently caused by pockets of methane exploding out of the melting permafrost. Has the Arctic methane time bomb begun to detonate in a more literal way than anyone imagined.
The “methane time bomb” is the popular shorthand for the idea that the thawing of the Arctic could at any moment trigger the sudden release of massive amounts of the potent greenhouse gas methane, rapidly accelerating the warming of the planet. Some refer to it in more dramatic terms: the Arctic methane catastrophe. Even the methane apocalypse.
Some scientists have been issuing dire warnings about this. There is even an Arctic Methane Emergency Group. Others, though, think that while we are on course for catastrophic warming, the one thing we don’t need to worry about is the so-called methane time bomb. The possibility of an imminent release massive enough to accelerate warming can be ruled out, they say. So who is right?
Few scientists think there is any chance of limiting warming to 2 °C, even though many still publicly support this goal. Our carbon dioxide emissions are the main cause of the warming, but methane is a significant player.
Methane is a highly potent greenhouse gas – causing 86 times as much warming per molecule as CO2 over a 20-year period. Fortunately, there’s very little of it in the atmosphere. Before humans arrived on the scene there was less than 1000 parts per billion. Levels started rising very slowly around 5000 years ago, possibly to due to rice farming. They’ve gone up more since the industrial age began: the fossil fuel industry is by far the single biggest source, followed by farting farm animals, leaking landfills and so on. Only a tiny percentage comes from melting Arctic permafrost.