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Archives for November 2013

Arctic and American Methane in Context

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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?

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References

  1. N. Shakhova, I. Semiletov, I. Leifer, V. Sergienko, A. Salyuk, D. Kosmach, D. Chernykh, C. Stubbs, D. Nicolsky, V. Tumskoy, and Ă. Gustafsson, "Ebullition and storm-induced methane release from the East Siberian Arctic Shelf", Nature Geoscience, vol. 7, pp. 64-70, 2013. http://dx.doi.org/10.1038/NGEO2007
  2. G. Whiteman, C. Hope, and P. Wadhams, "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", Doklady Earth Sciences, 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

Sea-level rise: What the experts expect

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In the long run, sea-level rise will be one of the most serious consequences of global warming. But how fast will sea levels rise? Model simulations are still associated with considerable uncertainty – too complex and varied are the processes that contribute to the increase. A just-published survey of 90 sea-level experts from 18 countries now reveals what amount of sea-level rise the wider expert community expects. With successful, strong mitigation measures, the experts expect a likely rise of 40-60 cm in this century and 60-100 cm by the year 2300. With unmitigated warming, however, the likely range is 70-120 cm by 2100 and two to three meters by the year 2300.
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Statistics and Climate

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Do different climate models give different results? And if so, why? The answer to these questions will increase our understanding of the climate models, and potentially the physical phenomena and processes present in the climate system.

We now have many different climate models, many different methods, and get a range of different results. They provide what we call ‘multi-model‘ and ‘multi-method‘ ensembles. But how do we make sense out of all this information?

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Global Warming Since 1997 Underestimated by Half

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A new study by British and Canadian researchers shows that the global temperature rise of the past 15 years has been greatly underestimated. The reason is the data gaps in the weather station network, especially in the Arctic. If you fill these data gaps using satellite measurements, the warming trend is more than doubled in the widely used HadCRUT4 data, and the much-discussed “warming pause” has virtually disappeared. [Read more…] about Global Warming Since 1997 Underestimated by Half

Simple physics and climate

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No doubt, our climate system is complex and messy. Still, we can sometimes make some inferences about it based on well-known physical principles. Indeed, the beauty of physics is that a complex systems can be reduced into simple terms that can be quantified, and the essential aspects understood.

A recent paper by Sloan and Wolfendale (2013) provides an example where they derive a simple conceptual model of how the greenhouse effect works from first principles. They show the story behind the expression saying that a doubling in CO2 should increase the forcing by a factor of 1+log|2|/log|CO2|. I have a fondness for such simple conceptual models (e.g. I’ve made my own attempt posted at arXiv) because they provide a general picture of the essence – of course their precision is limited by their simplicity.

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References

  1. T. Sloan, and A.W. Wolfendale, "Cosmic rays, solar activity and the climate", Environmental Research Letters, vol. 8, pp. 045022, 2013. http://dx.doi.org/10.1088/1748-9326/8/4/045022

Cows, Carbon and the Anthropocene: Commentary on Savory TED Video

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Guest post by Jason West and David Briske

Allan Savory delivered a highly publicized talk at a “Technology, Entertainment, Design (TED)” conference in February of this year (2013) entitled “How to fight desertification and reverse climate change.” Here we address one of the most dramatic claims made – that a specialized grazing method alone can reverse the current trajectory of increasing atmospheric CO2 and climate change.

The talk was attended by many conferees and has since been viewed on the TED website over 1.6 million times. It has received substantial acclaim in social media, some of which is available at the Savory Institute website, but it has also received considerable criticism (of particular note is a blog post from Adam Merberg and an article in Slate magazine. Although these criticism quickly followed Mr. Savory’s presentation and are broadly supported by the available science, his sweeping claims have continued to resonate with lay audiences. An apparent example is his invitation to deliver a speech to Swiss Re during their 150 year anniversary celebration in London in September, in which he is quoted as saying “…only now due largely to my TED talk on the desertification aspect of the global problem, was the public becoming aware of such hope in a world so short on solutions…”.
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