September 26, 2012

More Evidence Against a Methane Time Bomb

Over at Watts Up With That, Anthony Watts has highlighted a recent press release from the German Helmholtz Center for Ocean Research Kiel announcing the preliminary findings from an expedition this summer to the Greenland Sea (off the coast of Spitzbergen). The expedition on the German research vessel the Maria S. Merian was aimed at investigating the release of methane from the seafloor—one of the many potential apocalyptic positive feedback pathways which lead from an initial warming instigated by anthropogenic greenhouse gas emissions. Watts drew attention to the press release because the researchers were reporting that contrary to expectations, the release of methane from the seabed was found not to be a recent phenomenon (i.e., a result of global warming), but instead that many of the gas outlets had been active for long before local ocean temperatures have been rising.

According to the press release:

Above all the fear that the gas emanation is a consequence of the current rising sea temperature does not seem to apply.

And also, although the full details from the expedition’s data collections will not be known for several months, the scientists suggested that

[T]he observed gas emanations are probably not caused by human influence.

In Watts’ coverage, he contrasted this announcement with a rather alarmist one from a few years ago bemoaning the detection of the dreaded methane positive feedback loop, another step to our climate demise. Watts’ headline succinctly summarizes the current situation:

“Remember the panic over methane seeping out of the Arctic seabed in 2009? Never mind.”

And this is not the first time that evidence has been found that runs contrary to the methane apocalypse storyline.

Back in December of last year, in our article “Methane Time Bomb in Arctic Seas—Apocalypse Not,” we highlighted a report from New York Times blogger Andy Revkin that described results of an investigation of methane release from the Arctic seafloor off the coast of Siberia. In Siberia, as in the Greenland Sea, the investigators reported that methane release was a result of climate processes from long ago, rather than recent global warming.

Revkin aptly concluded:

So the next time you see a “science stunner” about Arctic methane time bombs, reach out to a couple of scientists working on this gas before you run to the ramparts.

With the new results highlighted by Watts, this sentiment now goes double.

And while we are at it, we may as well take a look at the latest update to the observations of the atmospheric concentration of methane, just as a sort of second opinion about whether the Arctic seafloor is becoming a significant new source of methane emissions. While Figure 1 show that atmospheric methane concentrations are again on the rise after rather mysteriously leveling off during the mid-1990s to mid-2000s, the rate of increase is still much less than was occurring during the 1980s—a period when the Arctic was a good 2°F cooler than it is now (Figure 2). So clearly other processes must be responsible for the recent upswing in methane concentrations. In his article last year, Revkin quoted leading methane researcher Ed Dlugokencky as stating:

[B]ased on what we see in the atmosphere, there is no evidence of substantial increases in methane emissions from the Arctic in the past 20 years.

Figure 1. Atmospheric methane concentrations (source: National Oceanic and Atmospheric Administration)

Figure 2. Arctic-wide annual average surface air temperature anomalies relative to the 1961-90 mean, based on land stations north of 60°N. Data are from the CRUTEM 3v dataset. Note this curve does not include marine observations (source: National Oceanic and Atmospheric Administration)

So what we have is no evidence that anthropogenic greenhouse gas emissions from the burning of fossil fuels are leading to runaway greenhouse warming spurred by a large and positive feedback from Arctic seabed methane release.

Anthony Watts seems quite correct in relegating this alarmist scenario to his “Climate Fail” file.

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