Arctic Warming May Capture More Methane Than It Releases

Expedition Fjord, Axel Heiberg Island, Nunavut, Canada. Nadia Mykytczuk, Laurentian University.

As the Arctic warms, methane will both be released from the permafrost and captured by flourishing bacteria. A study published in The ISME Journal concludes that, contrary to expectations, the second process may outpace the first.

If Climate Change were a blockbuster movie, this might be the moment when hope appears on the horizon, and as uplifting music swells we realize that all is not lost. Then again, it might be a false dawn, depending on the accuracy of the paper’s measurements of bacterial response to warmer temperatures.

Rising Greenhouse gasses trigger both positive and negative feedback processes. At some point, warming may initiate a runaway process that will rapidly take the world to temperatures incompatible with our civilization.

Arctic methane is the most likely suspect. The frozen north holds more than a trillion tonnes of carbon. Methane, particularly in the short term, is a much more powerful Greenhouse gas than carbon dioxide. Any large release in the form of methane will spur more warming, and more release. On hearing reports of methane release, Professor Jason Box memorably tweeted, “If even a small fraction of Arctic sea floor carbon is released to the atmosphere, we're fucked.”

Box was worrying about methane trapped underwater on continental slopes, but he could equally have been referring to the situation on land. This is why reports of holes appearing in Siberia last year sent shivers down many spines, although many climate scientists remained calm.

However the paper notes, “Methane (CH4) emission by carbon-rich cryosols at the high latitudes in [the] Northern Hemisphere has been studied extensively. In contrast, data on the CH4 emission potential of carbon-poor cryosols is limited, despite their spatial predominance.”

Warmer conditions make for more active bacteria, including some that oxidize atmospheric methane to methanol. First author Princeton’s Dr Chui Yim Lau and colleagues reported in April on a study of bacterial behavior on Axel Heiberg Island, Canada, under varying temperature conditions. They concluded that, if the Arctic warms by 5°–15°C (9°–27°F), the soil on Axel Heiberg will absorb methane 5-30 times as much methane as it does today. Further, they argued, this island’s acidic soils are representative of 87% of the global permafrost, far exceeding methane releasing areas.

Since publication errors in the original paper have been pointed out, the authors have revised some calculations. Their corrected paper has now been published, and reaches the same general conclusion.

“At our study sites, we are more confident that these soils will continue to be a sink under future warming,” Lau said. “We don't have a direct answer as to whether these Arctic soils will offset global atmospheric methane or not, but they will certainly help the situation.”

Even if correct, the finding is not a get out of jail free card for humanity. Fossil fuels alone could drown most major cities. Moreover, other possible tipping points, such as burning out of the Amazon rainforests, remain. But if Lau is right, it’s probably not too late to save the world. Or, as Box might put it, we’re not fucked yet.

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