Scientists Link Methane Formation by Bacteria in Shale Rock to Increases in Atmospheric Methane During Deglaciation; Production of the Gas Was Relatively Rapid:

Researchers from the University of Massachusetts-Amherst and Amherst College have linked the methane production of a subsurface consortium of fermentative and methanogenic bacteria in shale rock to increases in concentrations of atmospheric methane associated with the retreat of the continental ice sheets. The study also concluded that these bacteria produced large amounts of methane in a relatively short time.

Steven Petsch, assistant professor Geosciences at U Mass-Amherst, and his colleagues studied natural gas reservoirs in Michigan’s Antrim Shale. Their results are published in the February issue of the journal Geology.

Bacteria digested the carbon in the rocks and made large amounts of natural gas in a relatively short time, tens of thousands of years instead of millions. This suggests that it may be possible to seed carbon-rich environments with bacteria to create natural gas reservoirs.

—Steven Petsch

The study also helps explain high levels of methane in the atmosphere that occurred between ice ages, a trend recorded in ice cores taken from Greenland and Antarctica.

When the ice sheets retreated, it was like uncapping a soda bottle. Natural gas, which is mostly methane, was released from the shale into the atmosphere.

—Steven Petsch

The article is here (subscription access), and the press release about the paper is here.

So, what does this mean? As best I can tell, it’s distinctly bad news. The polar regions are already warming much quicker than expected, and there’s a truly mind blowing amount of ice on the move and/or melting in Alaska, Greenland, the Arctic, and the Antarctic. As best I can tell from my layman’s reading of the situation, the “methane surge” effect portrayed in the Petsch paper has yet to kick in, which only increases the possibility of a major “methane burp”, as others have called it, creating an enormous positive feedback effect. (The “methane burp” typically refers to the release of methane from defrosting tundra and undersea methane hydrate deposits.)

Again, this all ties back to the big questions: How much CO2 can we emit before we encounter truly horrific human impacts from global warming, and how much worse will global warming get, thanks to CO2 we’ve already dumped into the atmosphere, even if we very aggressively reduce future emissions?

For me, the most terrifying part of this mess is that we really don’t know the answers to those questions with any confidence. The rate of change we’re seeing, especially at the poles, is so far ahead of the predictions of the world’s best climate scientists that we should consider their advice–reduce CO2 emissions 80% by 2050–as a starting point, not a final goal.

The “magic ppm number issue” is one I’ve talked about before–just last month, in fact. Then I quoted an article in which James Hansen says that the magic concentration level at which global warming turns into an all-out disaster is not 550 ppm of CO2 or even the more recently quoted 450, but 350, which is less than the current level of about 383.

But we’re not talking about a binary state–exceed X ppm and we have sea levels rise 20 meters, and heat waves, droughts, floods, and hurricanes decimating cities around the world, but stay just under that level and everything is just peachy. We’re already locked in to further warming, even if all new CO2 emissions stopped today. Given the feedbacks involved and our incomplete understanding of them, there’s no way to be sure just how bad things would get over the next 20 or 30 years.

One thing we can be sure of: The more CO2 we pump into the atmosphere, the worse things will get.

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