Methane release from Arctic permafrost found to be > doubled by unexpectedly abrupt thawing

A NASA-funded international team observe an impact of warming not foreseen or incorporated in climate models: emissions from carbon deep in thermokarst lakes.

NASA reports: “An international team of U.S. and German researchers found that abrupt thawing more than doubles previous estimates of permafrost-derived greenhouse warming. They found that the abrupt thaw process increases the release of ancient carbon stored in the soil 125 to 190 percent compared to gradual thawing alone. What’s more, they found that in future warming scenarios defined by the Intergovernmental Panel on Climate Change, abrupt thawing was as important under the moderate reduction of emissions scenario as it was under the extreme business-as-usual scenario. This means that even in the scenario where humans reduced their global carbon emissions, large methane releases from abrupt thawing are still likely to occur.”

“These ancient greenhouse gases, produced from microbes chewing through ancient carbon stored in the soil, range from 2,000 to 43,000 years old. Walter Anthony and her colleagues captured methane bubbling out of 72 locations in 11 thermokarst lakes in Alaska and Siberia to measure the amount of gas released from the permafrost below the lakes, as well as used radiocarbon dating on captured samples to determine their age. They compared the emissions from lakes to five locations where gradual thawing occurs. In addition, they used the field measurements to evaluate how well their model simulated the natural field conditions.”

A deadly positive feedback from melting permafrost has long been a fear of mine, ever since I began working on climate change in the mid 1980s. I chronicle the growth of this fear, and the evidence for it, in The Carbon War. I wish I could offer an ameliorating thought. Unfortunately, I can’t. This is extremely bad news – and it will not even be noticed by most of the political class.

Image: screenshot of NASA video



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