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How Many Cans?

Filed under: — david @ 22 March 2014

XKCD, the brilliant and hilarious on-line comic, attempts to answer the question

How much CO2 is contained in the world’s stock of bottled fizzy drinks? How much soda would be needed to bring atmospheric CO2 back to preindustrial levels?

The answer is, enough to cover the Earth with 10 layers of soda cans. However, the comic misses a factor of about two, which would arise from the ocean. The oceans have been taking up carbon throughout the industrial era, as have some parts of the land surface biosphere. The ocean contains about half of the carbon we’ve ever released from fossil fuels. We’ve also cut down a lot of trees, which has been more-or-less compensated for by uptake into other parts of the land biosphere. So as a fraction of our total carbon footprint (fuels + trees) the oceans contain about a third.

At any rate, the oceans are acting as a CO2 buffer, meaning that it’s absorbing CO2 as it tries to limit the change to the atmospheric concentration. If we suddenly pulled atmospheric CO2 back down to 280 ppm (by putting it all in cans of soda perhaps), the oceans would work in the opposite direction, to buffer our present-day higher concentration by giving up CO2. The land biosphere is kind of a loose cannon in the carbon cycle, hard to predict what it will do.

Ten layers of soda cans covering the whole earth sounds like a lot. But most of a soda can is soda, rather than CO2. Here’s another statistic: If the CO2 in the atmosphere were to freeze out as dry ice depositing on the ground, the dry ice layer would only be about 7 millimeters thick. I guess cans of soda pop might not be the most efficient or economical means of CO2 sequestration. For a better option, look to saline aquifers, which are porous geological formations containing salty water that no one would want to drink or irrigate with anyway. CO2 at high pressure forms a liquid, then ultimately reacts with igneous rocks to form CaCO3.

Further Reading

Tans, Pieter. An accounting of the observed increase in oceanic and atmospheric CO2 and
an outlook for the Future. Oceanography 22(4) 26-35, 2009

Carbon dioxide capture and storage IPCC Report, 2005

Arctic and American Methane in Context

Filed under: — david @ 24 November 2013

Lots of interesting methane papers this week. In Nature Geoscience, Shakhova et al (2013) have published a substantial new study of the methane cycle on the Siberian continental margin of the Arctic Ocean. This paper will get a lot of attention, because it follows by a few months a paper from last summer, Whiteman et al (2013), which claimed a strong (and expensive) potential impact from Arctic methane on near-term climate evolution. That economic modeling study was based on an Arctic methane release scenario proposed in an earlier paper by Shakhova (2010). In PNAS, Miller et al (2013) find that the United States may be emitting 50-70% more methane than we thought. So where does this leave us?

More »

References

  1. N. Shakhova, I. Semiletov, I. Leifer, V. Sergienko, A. Salyuk, D. Kosmach, D. Chernykh, C. Stubbs, D. Nicolsky, V. Tumskoy, and . Gustafsson, "Ebullition and storm-induced methane release from the East Siberian Arctic Shelf", Nature Geosci, vol. 7, pp. 64-70, 2013. http://dx.doi.org/10.1038/NGEO2007
  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. N.E. Shakhova, V.A. Alekseev, and I.P. Semiletov, "Predicted methane emission on the East Siberian shelf", Dokl. Earth Sc., vol. 430, pp. 190-193, 2010. http://dx.doi.org/10.1134/S1028334X10020091
  4. S.M. Miller, S.C. Wofsy, A.M. Michalak, E.A. Kort, A.E. Andrews, S.C. Biraud, E.J. Dlugokencky, J. Eluszkiewicz, M.L. Fischer, G. Janssens-Maenhout, B.R. Miller, J.B. Miller, S.A. Montzka, T. Nehrkorn, and C. Sweeney, "Anthropogenic emissions of methane in the United States", Proceedings of the National Academy of Sciences, vol. 110, pp. 20018-20022, 2013. http://dx.doi.org/10.1073/pnas.1314392110

Science of Climate Change online class starting next week on Coursera

Filed under: — david @ 14 October 2013

Maybe you remember the rollout a few years ago of Open Climate 101, a massive open online class (MOOC) that was served sort of free-range from a computer at the University of Chicago. Now the class has been entirely redone as Global Warming: The Science of Climate Change within the far slicker Coursera platform. Beginning on October 21, the class is free and runs for 8 weeks. The videos have been reshot in a short and punchy (2-10 minute) format, for example here (8:13). These seem like they will be easier to watch than traditional 45-minute lectures from a classroom. It’s based on, and will show you how to play with, all-new on-line computer models, including extensive new browsing systems for global climate records and model results from the new AR5 climate model archive, an ice sheet model you can clobber with slugs of CO2 as it evolves, and more. Come and watch the train wreck join the fun! More »

The scientific debate on climate change

Filed under: — david @ 24 May 2013

by Jill and David Archer

Methane game upgrade

Filed under: — david @ 14 June 2012

Walter Anthony et al (2012) have made a major contribution to the picture of methane emissions from thawing Arctic regions. Not a game-changer exactly, but definitely a graphics upgrade, bringing the game to life in stunningly higher resolution (/joke).
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