Friday, May 21, 2010

Methane Release from East Siberian Arctic Shelf

Global warming creates a number of positive feedback cycles in which warming creates the conditions for accelerated warming. An example would be higher temperatures reducing the extent of Arctic sea ice, which allows the Arctic Ocean to absorb more sunlight and warm faster. There is one feedback in particular we should be scared shitless about: methane feedbacks.

Methane (CH4, same as that natural gas you might use to cook) is a greenhouse gas 25 times more potent than CO2. Not only do humans emit methane in a variety of ways, but feedback cycles from warming caused primarily by our CO2 emissions drive further methane release. Higher temperatures in the Arctic and Antarctic (and remember that higher latitudes experience a greater level of warming) cause the frozen tundra soils, or permafrost, to melt. The melting triggers anaerobic decomposition of organic material in the soil, which creates methane as a byproduct. Joe Romm has been raising the visibility of this issue for a long time because the feedback cycle is not incorporated into climate models. That suggests that we need to cut emissions faster and deeper than the models say to stabilize global temperature at the same level.

Via Romm's blog Climate Progress, I came across a study that found a potentially more dangerous source of methane: submerged permafrost in shallow seas off the eastern coast of Siberia. In colder times, the area was tundra above sea level but in this warmer epoch it lies under water. The submerged permafrost contains massive amounts of methane that, if released, could cause the rate of global warming to increase hugely. Check out Romm's summary in its entirety as it condenses the findings quite well and contextualizes them with regard to overall climate and emissions trends.

The study found that already the area is emitting more methane into the atmosphere than the rest of the ocean does. The permafrost/methane formations show signs of instability as warming has created 100 hotspots of methane release. The really scary part is how the release of even a small amount of the methane stored in the East Siberian Arctic Shelf would destabilize the atmosphere:
“The release to the atmosphere of only one percent of the methane assumed to be stored in shallow hydrate deposits might alter the current atmospheric burden of methane up to 3 to 4 times,” Shakhova said. “The climatic consequences of this are hard to predict.”
Yikes. Given that the climate models used to make climate policy don't incorporate major feedbacks, we knew earlier that we had to make greater emissions cuts than the models say to stabilize at the same temperatures and in doing so avoid the worst impacts of global warming. This study suggests that we have to make those cuts not just to avoid a greater increment of warming, but to avoid a drastic jump in greenhouse gas levels from methane release that would greatly multiply the effect of human emissions and push our climate into a dramatically warmer era (we're talking like 10 degrees F warmer with commensurate consequences for people and ecosystems). I leave with you with the climate blogging master Romm himself:
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
In short, the would-be point of atmospheric stabilization, 550 ppm isn’t stable at all — it is past the point of no return. We must stay well below 450 ppm to save the tundra and hence the climate. The new research underscores that conclusion, especially since the planet will keep warming (slowly) for decades even once we slash emissions to near zero.

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