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Methane emissions vastly surpass previous estimates

Date:
November 25, 2013
Source:
Carnegie Institution
Summary:
Government calculations of total US methane emissions may underestimate the true values by 50 percent, a new study finds. The results cast doubt on a recent Environmental Protection Agency decision to downscale its emissions estimate.
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Government calculations of total U.S. methane emissions may underestimate the true values by 50 percent, a new study finds. The results are published the week of November 25 in the early online edition of the Proceedings of the National Academy of Sciences, and cast doubt on a recent Environmental Protection Agency decision to downscale its emissions estimate.

Carnegie's Anna Michalak, Harvard's Scot Miller and Steven Wofsy, and colleagues used atmospheric methane observations from across North America in 2007 and 2008 to improve estimates of methane gas emissions from a variety of human sources, including agriculture and fossil fuel drilling and refining.

The study found large discrepancies with government estimates in some regions of the United States, particularly the south-central US, where total methane emissions were 2.7 times greater than those reported in most inventories. Emissions from oil and gas drilling and processing in this region could account for 50% of that total, representing a source of methane almost five times higher than in the most commonly used global emissions database.

Methane is the second-most important greenhouse gas after carbon dioxide, and the study findings may help inform national and state greenhouse gas reduction strategies, according to the authors.

The team used modeling tools developed by Michalak's lab that make it possible to trace variations in atmospheric methane measurements back to emissions throughout the U.S., and to relate the emissions to known economic sectors. The methods thereby provide a direct constraint on total emissions, as well as provide insight into what is behind them.


Story Source:

The above post is reprinted from materials provided by Carnegie Institution. Note: Materials may be edited for content and length.


Journal Reference:

  1. 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, C. Sweeney. Anthropogenic emissions of methane in the United States. Proceedings of the National Academy of Sciences, 2013; DOI: 10.1073/pnas.1314392110

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Carnegie Institution. "Methane emissions vastly surpass previous estimates." ScienceDaily. ScienceDaily, 25 November 2013. <www.sciencedaily.com/releases/2013/11/131125164442.htm>.
Carnegie Institution. (2013, November 25). Methane emissions vastly surpass previous estimates. ScienceDaily. Retrieved August 1, 2015 from www.sciencedaily.com/releases/2013/11/131125164442.htm
Carnegie Institution. "Methane emissions vastly surpass previous estimates." ScienceDaily. www.sciencedaily.com/releases/2013/11/131125164442.htm (accessed August 1, 2015).

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