Methane tipping point is close… very close

A possible explanation for the increasing methane concentrations in the atmosphere. From Yale360:

British and German scientists have discovered 250 plumes of methane gas rising from the thawing seabed off the Spitsbergen archipelago in the Norwegian Arctic, apparently a result of the warming of the West Spitsbergen current. The researchers measured the plumes rising from the seabed at a depth of 150 to 400 meters (500 to 1,300 feet). The methane — a potent greenhouse gas — is being released by frozen methane hydrates on the sea floor, which are thawing as a result of a 1 degree C (1.8 F) warming of the West Spitsbergen current in the last 30 years, the scientists said. Most of the methane is absorbed by the ocean before it reaches the surface, but the gas increases the acidity of the ocean, which inhibits the ability of marine creatures to grow shells. Scientists fear that as the world’s oceans warm, huge amounts of methane will be released. The Spitsbergen researchers said they were surprised by the large number of methane plumes. “Our survey was designed to work out how much methane might be released by future ocean warming,” said one scientist. “We did not expect to discover such strong evidence that this process has already started.”

(h/t Michael Tobis)

And here is the study abstract:

More than 250 plumes of gas bubbles have been discovered emanating from the seabed of the West Spitsbergen continental margin, in a depth range of 150–400 m, at and above the present upper limit of the gas hydrate stability zone (GHSZ). Some of the plumes extend upward to within 50 m of the sea surface. The gas is predominantly methane. Warming of the northward-flowing West Spitsbergen current by 1°C over the last thirty years is likely to have increased the release of methane from the seabed by reducing the extent of the GHSZ, causing the liberation of methane from decomposing hydrate. If this process becomes widespread along Arctic continental margins, tens of Teragrams of methane per year could be released into the ocean.

This is definitely not good news. All the more reason to demand strong action as soon as possible.

Tamino sums up the remaining questions:

1. Does the behavior observed at the West Spitzbergen continental margin extend to most of the Svalbard archipelago, or even to much of the Artic continental margins?
2. How much of the released methane will end up in the atmosphere, and how quickly — are we witnessing a greenhouse-gas feedback in action?
3. What other sources of methane increase are responsible for the recent increase in atmospheric concentration?

And arrives at a rather unsettling conclusion:

given the uncertainty associated with the release of methane from the sea floor, at least we can hope that we’re no worse off than we already knew.

Hardly comforting. Clearly there is a rather urgent need to better understand the methane cycle.