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How much methane came out of that hole in Siberia?

Filed under: — david @ 13 August 2014

Siberia has explosion holes in it that smell like methane, and there are newly found bubbles of methane in the Arctic Ocean. As a result, journalists are contacting me assuming that the Arctic Methane Apocalypse has begun. However, as a climate scientist I remain much more concerned about the fossil fuel industry than I am about Arctic methane. Short answer: It would take about 20,000,000 such eruptions within a few years to generate the standard Arctic Methane Apocalypse that people have been talking about. Here’s where that statement comes from:

How much methane emission is “a lot”? The yardstick here comes from Natalie Shakhova, an Arctic methane oceanographer and modeler at the University of Fairbanks. She proposed that 50 Gton of methane (a gigaton is 1015 grams) might erupt from the Arctic on a short time scale Shakhova (2010). Let’s call this a “Shakhova” event. There would be significant short-term climate disruption from a Shakhova event, with economic consequences explored by Whiteman et al Whiteman et al (2013). The radiative forcing right after the release would be similar to that from fossil fuel CO2 by the end of the century, but subsiding quickly rather than continuing to grow as business-as-usual CO2 does.

I and others have been skeptical of the possibility that so much methane could escape from the Arctic so quickly, given the century to millennial time scale of warming the permafrost and ocean sediments, and point out that if the carbon is released slowly, the climate impacts will be small. But now that explosion holes are being found in Siberia, the question is

How much methane came out of that hole in Siberia? The hole is about 80 meters in diameter and 60-100 meters deep.

It’s hard to say exactly how much methane did this, because perhaps the crater allowed methane to be released from the surrounding soil. There may be emissions in the future from permafrost melting laterally from the sides of the hole. But for a start let’s assume that the volume of the hole is the same as the volume of the original, now escaped, bubble. Gases are compressible, so we need to know what its pressure was. The deeper in the Earth it was, the higher the pressure, but if we are concerned about gas whose release might be triggered by climate warming, we should look for pockets that come close to the surface. Deep pockets might take thousands of years for surface warming to reach. The mass of a solid cap ten meters thick would increase the pressure underneath it to about four atmospheres, plus there may have been some overpressure. Let’s assume a pressure of ten atmospheres (enough to hold up the atmosphere plus about 30 meters of rock).

If the bubble was pure methane, it would have contained about … wait for it … 0.000003 Gtons of methane. In other words, building a Shakhova event from these explosions would take approximately 20,000,000 explosions, all within a few years, or else the climate impact of the methane would be muted by the lifetime effect.

What about the bubbles of methane they just found in the Arctic ocean? There were reports this summer of a new expedition to the Siberian margin, documenting vast plumes of methane bubbles rising from sediments ~500 meters water depth.

It is certainly believable that warming ocean waters could trigger an increase in methane emissions to the atmosphere, and that the time scale for changing ocean temperatures can be fast due to circulation changes (we are seeing the same thing in the Antarctic). But the time scale for heat to diffuse into the sediment, where methane hydrate can be found, should be slow, like that for permafrost on land or slower. More importantly, the atmospheric methane flux from the Arctic Ocean is really small (extrapolating estimates from Kort et al 2012), even compared with emissions from the Arctic land surface, which is itself only a few percent of global emissions (dominated by human sources and tropical wetlands).

In conclusion, despite recent explosions suggesting the contrary, I still feel that the future of Earth’s climate in this century and beyond will be determined mostly by the fossil fuel industry, and not by Arctic methane. We should keep our eyes on the ball.

References

  1. N.E. Shakhova, V.A. Alekseev, and I.P. Semiletov, "Predicted methane emission on the East Siberian shelf", Doklady Earth Sciences, vol. 430, pp. 190-193, 2010. http://dx.doi.org/10.1134/S1028334X10020091
  2. G. Whiteman, C. Hope, and P. Wadhams, "Climate science: Vast costs of Arctic change", Nature, vol. 499, pp. 401-403, 2013. http://dx.doi.org/10.1038/499401a
  3. E.A. Kort, S.C. Wofsy, B.C. Daube, M. Diao, J.W. Elkins, R.S. Gao, E.J. Hintsa, D.F. Hurst, R. Jimenez, F.L. Moore, J.R. Spackman, and M.A. Zondlo, "Atmospheric observations of Arctic Ocean methane emissions up to 82° north", Nature Geoscience, vol. 5, pp. 318-321, 2012. http://dx.doi.org/10.1038/NGEO1452

106 Responses to “How much methane came out of that hole in Siberia?”

  1. 101
    Hank Roberts says:

    Better it be done in an almost carbon neutral way…. I don’t think an authority exists on the planet that is capable of … carbon sequestration…. some Russian scientists … fear … thousands of those blowouts and the chronic emissions from them ….

    Fixed that for ya.
    It’s a scary story sold to pretend their infrastructure development is climate-friendly.
    It’s a flat lie to cover investing money in short-term profit from gas instead of in alternatives.
    No credible argument for “depressurizing, selling, and burning” is being made.
    They want to burn it before it loses its value as better alternatives are already threatening that.

  2. 102
    Hank Roberts says:

    P.S. for Leland Palmer: the Russians are not alone, being in a hurry to extract more gas fast before the value collapses; soon enough it will be left in the ground as uneconomical to extract. They know.
    You can look this up:
    https://www.google.com/search?q=electric+industry+gas+profit+model+solar+photovoltaic

  3. 103
    Leland Palmer says:

    That’s a great example of selective quoting, but I have to say that it’s not at all accurate, in several different ways. The Russians are not proposing to deep inject the CO2 from their natural gas and export the energy as electricity, for example – I’m proposing that. If the AMEG folks are proposing that too, that’s great. It’s an obvious solution, though. Also, most of the methane is in the deep gas deposits, not in the possible regional layer of shallow methane hydrate possibly associated with the Yamal crater.

    I hope that better energy alternatives do arise. But the Russians could probably sell their gas for a lot less than they do now, and still make a profit. Solar energy and other alternatives are very diffuse sources of energy, and getting the cost down far enough to put the fossil fuel interests out of business is going to be very, very difficult.

    We better hope that some form of carbon storage does materialize, though – because quite a few published studies say that getting back to 350 ppm of atmospheric CO2 without some form of carbon capture and storage is infinitely costly, and so effectively impossible.
    I believe myself that we’re going to have to go to carbon negative energy production by combining biomass energy with carbon capture and storage to avoid a methane catastrophe and mass extinction event – if it is not already too late.

    If we put too many constraints on solving this global warming problem, it’s going to be impossible to solve, I think. Eventually, we’re going to have to do what works scientifically, that keeps methane out of the atmosphere, and takes CO2 back out of it – if it is not already too late to stop positive feedback generated low level runaway global heating.

  4. 104
    Hank Roberts says:

    > If the AMEG folks are proposing that too, that’s great

    They aren’t.

    > to put the fossil fuel interests out of business
    > is going to be very, very difficult.

    The impossible takes a little longer.

  5. 105
    Robyn Wagoner says:

    Hello David,
    I want to thank you for the wonderful book assigned in my grad school class on The Global Carbon Cycle. I also want to point out that Natalia Shakhova has recently taken cores of the East Siberian Arctic subsea permafrost. She has observed first hand that they have thawed as far down as 15 meters in an area that has only been submerged for 150-200 years, not the thousands of years that you predicted such thawing would require. https://m.youtube.com/watch?v=dQDVr1eMLK8

  6. 106

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