Seeping Methane a Reason To Panic?

Methane is leaking from the floor of the Arctic ocean north of Siberia, according to a scientific study released last week. Scientists have long warned about the destabilizing potential of methane locked away in the Artic tundra. They have only recently turned their gaze to the vast stores of the gas trapped under the ocean floor. Although carbon dioxide makes up the vast majority of global greenhouse gases, methane is 25 times more potent an incubator than CO2.

Most methane emissions — 60 percent — are the byproduct of human activity: rice paddies, dumps, livestock farming and energy generation top the list of culprits. The rest come from natural sources, mostly wetlands and Arctic permafrost, whether in the tundra or under the ocean floor.

As the climate warms, permafrost degrades, releasing methane into the surrounding atmosphere. This methane, in turn, warms the climate further, which pushes the permafrost to produce more methane, and so on. This is called a positive feedback loop, one of several in the climate system. (The name can be misleading because the results are not at all positive.)

When folks talk about a tipping point in the climate, they mean a temperature threshold past which every added bit of warming is amplified by one or more of these feedback loops, thereby increasing the chance of catastrophic warming. This is why we must keep the global thermostat under 2 degrees Celsius - after that, not only do climate impacts — droughts, food shortages, storms, heatwaves, sea level rise, mass extinctions — become increasingly severe, but temperature bumps begin to feed on themselves. These feedback loops, combined with the heat-trapping power of methane, are what keep climate scientists up at night. (And by the way, we're not on track to keep warming to 2 degrees Celsius.)

So, do these Arctic burps signal the onset of a methane-climate feedback loop? It's simply too early to tell. Scientists have just started monitoring methane emissions in the area, so there are still too many known unknowns to say for sure.

We don't know if the emissions are new — the result of recent warming — or whether they've been there for, unnoticed, for decades.

Most importantly, we don't know how rapidly these emissions could increase as the Arctic warms, and thus whether a catastrophic methane leak is imminent. However, climate scientist David Archer points out that because methane, unlike CO2, only stays in the atmosphere for a decade, the methane release would have to be unexpectedly massive and sudden to bring on climate catastrophe all by itself. Which would be good news if we weren't belching carbon dioxide into the atmosphere at ever-increasing rates.

Takeaway: We need a lot more study, and a watchful eye, on these Arctic leaks.

Photo credit: Zina Deretsky, National Science Foundation