Is This Why Heat-Trapping Methane Emissions Are On The Rise?
Joe
Romm
Think Progress,
May, 2014
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.”
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.
The permafrost carbon feedback is one of the important and likely consequences of climate change, and it is certain to trigger additional warming … Instead of reducing emissions, we currently are on track with the most dire scenario considered by the IPCC.
So
permafrost thawing is “certain to trigger additional warming” —
and yet the super-conservative IPCC modelers ignored
any warming impact from
the permafrost! This in spite of the fact that the IPCC
itself concluded
in its recent assessment of
climate science:
It is virtually certain that near-surface permafrost extent at high northern latitudes will be reduced as global mean surface temperature increases. By the end of the 21st century, the area of permafrost near the surface (upper 3.5 m) is projected to decrease by between 37% (RCP2.6) to 81% (RCP8.5) for the model average.
While
the IPCC modelers failed to incorporate this catastrophic loss of the
top ten feet of permafrost, other researchers didn’t. One major
2012 study found
that the carbon feedback alone from thawing permafrost will add up to
1.5°F to total global warming by 2100.
This
new research is yet more evidence that given our do-little path
climate policy, we
are headed towards 10°F warming compared
to preindustrial levels, which is terra
incognita forterra
firma and
its inhabitants.
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