Study: atmospheric methane increases largely attributable to Northern Wetlands

[Bill USA]

http://thinkprogress.org/climate/2014/05/02/3433592/methane-wetlands-permafrost/

A new international study offers a worrisome answer to the question of why global levels of methane — one of the most potent heat-trapping greenhouse gases — have begun rising again in recent years.

The study, “A synthesis of methane emissions from 71 northern, temperate, and subtropical wetlands,” finds that the rise “likely stems from wetland emissions.”


Global average methane levels (Image: NOAA via MNN)

The news here is that while scientists had thought methane emissions from the wetlands would be largest in the tropics, in fact northern wetlands (such as the fens, Canada’s most common form of wetland) are also major contributors, as the 19-author study concludes. The lead author, Canadian Prof. Merritt Turetsky, explained:

“But our analyses show that northern fens, such as those created when permafrost thaws, can have emissions comparable to warm sites in the tropics, despite their cold temperatures … Not only are fens one of the strongest sources of wetland greenhouse gases, but we also know that Canadian forests and tundra underlain by permafrost are thawing and creating these kinds of high methane-producing ecosystems.”

This is exceedingly worrisome for three reasons. First, the permafrost contains twice as much carbon as the atmosphere does today. Second, the Intergovernmental Panel on Climate Change (IPCC) reported last year that methane (CH4) is a far more potent greenhouse gas than we had previously realized — a stunning 86 times more potent than carbon dioxide over a 20-year time frame. Third, since warming permafrost releases methane that in turn increases the rate of global warming, this process represents a positive or amplifying carbon cycle feedback.
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