Undersea Methane Is Leaking--Should We Panic?

by Bradford Plumer | March 5, 2010

A new study about how methane stores in the Arctic seabed are "destabilizing and venting" is getting a lot of attention. Here's a write-up from the Times:

Climate scientists have long warned that global warming could unlock vast stores of the greenhouse gas methane that are frozen into the Arctic permafrost, setting off potentially significant increases in global warming. Now researchers at the University of Alaska, Fairbanks, and elsewhere say this change is under way in a little-studied area under the sea, the East Siberian Arctic Shelf, west of the Bering Strait.

Natalia Shakhova, a scientist at the university and a leader of the study, said it was too soon to say whether the findings suggest that a dangerous release of methane looms. In a telephone news conference, she said researchers were only beginning to track the movement of this methane into the atmosphere as the undersea permafrost that traps it degrades.

But climate experts familiar with the new research reported in Friday’s issue of the journal Science that even though it does not suggest imminent climate catastrophe, it is important because of methane’s role as a greenhouse gas. Although carbon dioxide is far more abundant and persistent in the atmosphere, ton for ton atmospheric methane traps at least 25 times as much heat.

Just to clarify a bit: Yes, methane is bubbling up from the East Siberian Arctic Shelf, but because methane emissions in the area haven't been tracked for very long, it's still not clear whether these are actually new emissions—possibly caused by warming in the Arctic—or whether this leak has been around for centuries and it's just that no one ever noticed it before. But the study notes that there's an "urgent need" to monitor the area better, since there's a decent chance that warmer temperatures could weaken the undersea permafrost even further and allow even more methane to bubble up, causing yet more warming.

So how worried should we be about potential methane feedbacks? Joe Romm offers a dire view: "It is increasingly clear that if the world strays significantly above 450 ppm atmospheric concentrations of carbon dioxide for any length of time, we will find it unimaginably difficult to stop short of 800 to 1000 ppm. ... No climate model currently incorporates the amplifying feedback from methane released by a defrosting tundra." That's why the these feedbacks are so unnerving—no one's quite sure how the Earth will respond.

But on the flip side, Dot Earth talks to a few researchers who are a little more sanguine: "But [NOAA's Ed] Dlugokencky, like quite a few other scientists assessing Arctic warming, sees no evidence for a 'tipping point' beyond which this cascades uncontrollably. That doesn’t mean this is impossible, just that there’s no evidence pointing to such a prospect." That's somewhat comforting, though everyone seems to agree it would be incredibly stupid to just keep heating up the Earth and finding out for sure what happens.

Meanwhile, David Archer has a good, sober discussion of the paper at RealClimate. His bottom line: "For methane to be a game-changer in the future of Earth’s climate, it would have to degas to the atmosphere catastrophically, on a time scale that is faster than the decadal lifetime of methane in the air. So far no one has seen or proposed a mechanism to make that happen." So while these methane leaks need a lot more study, they're not cause for panic at the moment. There's enough to worry about when it comes to climate change as it is.

Source URL: http://www.newrepublic.com//blog/the-vine/undersea-methane-leaking-should-we-panic