Unexpected future boost of methane possible from Arctic permafrost

Federico Mansilla
Agosto 19, 2018

Even more, these water bodies accelerate the permafrost meltdown ensuring the proper ecosystem for the development of microbes that generate methane, carbon dioxide, and other greenhouse gases that, at their turn, accelerate the climate change.

Existing models now attribute about 20 percent of the permafrost carbon feedback this century to methane, with the rest due to carbon dioxide from terrestrial soils.

"The mechanism of abrupt thaw and thermokarst lake formation matters a lot for the permafrost-carbon feedback this century", said first author Katey Walter Anthony from University of Alaska Fairbanks in the US. They measured the growth of these lakes and also recorded the amount of methane bubbling up top their surface.

Permafrost thaw may accelerate, and it is more devastating and potent than scientists originally thought. However, a process begins in the event that the permafrost thaws out - soil microbes located in the permafrost convert the carbon into carbon dioxide and methane.

So, we measured the carbon emissions in 72 different locations in 11 thermokarst lakes in areas of Siberia and Alaska, and in five places without lakes, to understand, how much is a greenhouse gas, and also with the goal of measuring the age of contained carbon.

For centuries, a massive store of carbon has been locked underground in the Arctic's permanently frozen soil known as permafrost. "This is already happening, just not very fast, but in a few decades will reach its peak".

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The researchers found the release of greenhouse gases beneath thermokarst lakes is relatively rapid, with deep thawing taking place over the course of decades.

American and German researchers found that abrupt thawing more than doubles previous estimates of permafrost-derived greenhouse warming. "Ancient greenhouse gases go out".

Moreover, the team also found that this abrupt thawing was still a concern even under a scenario in which humans tried to rein in their greenhouse-gas production and slow climate change.

As part of the study, researchers observed hundreds of thermokarst lakes in Alaska and Siberia during a 12-year period.

They compared the emissions from lakes to five locations where gradual thawing occurs. Adding thermokarst methane to the models makes the feedback's effect similar to that of land-use change, which is the second-largest source of manmade warming.

Team members with the Alfred Wegener Institute (AWI) for Polar and Marine Research in Germany then used U.S. Geological Survey-NASA Landsat satellite imagery from 1999 to 2014 to determine the speed of lake expansion across a large region of Alaska. In particular, a team of scientists have paid special attention to the melting of ice under water, known as thermokarst lakes. "When the lakes form, they flash-thaw these permafrost areas", said Walter Anthony, an associate professor with UAF's Water and Environmental Research Center. The released gases, built with carbon atoms between 2,000 and 43,000 years old, quickly rise up through the lake and into the atmosphere.

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