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Methane, more scary than we thought

Methane’s Contribution to Global Warming Is Worse than You Thought

It seems we've been "fudging the numbers" in a sense, when comparing the global warming potential of methane to CO2. When global warming potential (GWP) of a gas is calculated, a time frame is assumed. The IPCC decided to use a 100 year time frame.

With a 100 year time frame methane heats up the planet 21 times as much as CO2. The problem with that assumption is that we don't have 100 years. A 20 year time frame would be much more realistic, given the urgency of climate crisis. With a 20 year time frame...

... any CH4 released today is at least 56 times more heat-trapping than a molecule of C02 also released today. And because of the way it reacts in the atmosphere, the number is probably even higher, according to research conducted by  Drew Shindell , a scientist at NASA’s Goddard Space Center. [emphasis mine]


What if we were to use the IPCC’s 20-year comparison instead of its 100-year comparison? For starters, it would force us to get much more serious about tackling  the sources of methane emissions. Here in the US, the top methane sources are the decomposition of wastes in landfills, agriculture (from ruminant digestion), and leaks from natural gas drilling and transmission. A new emphasis on methane would require us to get smarter about capturing methane at landfills, reduce the market incentives that encourage Americans’ meat-heavy diets, and ensure that methane isn’t leaking from fracking operations.

But beyond the policy specifics, adopting the 20-year global warming potential comparisons would be useful for changing how we think about climate change.

And we appear to be approaching some irrevocable tipping points that will create powerful negative feedback loops, the most worrisome being  the release of methane  stores at the bottom of the ocean and locked into sub-Arctic permafrost.

Image from Arctic Methane Release Tipping Point Diagram
With 56 times as much warming as CO2 in mind, we'd take this feedback more seriously.

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    Ruth Anthony-Gardner

    Woods Hole scientists call for research on the tipping point for catastrophic permafrost melting.

    Top Scientist — Threat of Catastrophic Permafrost Thaw is “Real and...

    A 2 C global warming threshold is generally thought to be the point at which enough of the Arctic permafrost will go into catastrophic destabilization, to result in a global warming amplifying feedback that then thaws all or most of the rest.

    The problem is we’ve already emitted enough CO2, methane and other greenhouse gasses to warm the Earth by 2-4 degrees Celsius long term and by around 1.4 to 1.9 degrees Celsius this Century. 

    Dr. Holmes’ and his Woods Hole colleagues are calling for a focused effort to more accurately nail down that tipping point. To give us a better idea how close we really are ...

    ... there may be some risk that enough of the store could become unstable at lesser levels of warming — crossing the tipping point sooner than expected.

    Are large Siberian fires … indicative that the Arctic permafrost carbon stores are nearing a critical tipping? [text order altered]

    This news is disturbing, insofar as it's generally agreed we've already locked ourselves into more than 2°C warming with fossil fuel infrastructure investments. Japan is helping many countries build even more coal plants, a new tar sands site is starting in the US, and a bill encouraging widespread logging in US National Forests has passed the House. <groan> Is spiraling catastrophic heating just a matter of decades? Have we already guaranteed our doom by the end of this century or early next?

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      Ruth Anthony-Gardner

      Yesterday a large portion of the Arctic Ocean under which methane lies had an air temperature 20°C above normal for this time of year.

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        Ruth Anthony-Gardner

        Study of pingos (ice mounds) discovered off the shore of the Sibera, near Yamal where land based pingos erupted to create blowholes, shows they're also caused by melting permafrost. Two undersea pingos were studied by radar. One was leaking copious amounts of recently-generated methane.

        Methane Bubbling up and melting down

        This is a land-based pingo.

        At sea, the mounds, measuring 70m-100m across and nicknamed pingos, are believed to be formed when is methane released from soil that has been thawed by warming ocean water. On shore, such mounds are generally smaller and formed in a slightly different manner, but both may be the precursor to sinkholes, which form after methane makes its way to the surface and either dissipates slowly into the atmosphere or blasts out. [emphasis mine]

        Sudden methane releases from pingos might explain the extra high outlier methane readings periodically recorded. Of course we wouldn't be aware of such events unless a ship or plane happened to be nearby and recording it.