Reduced biomass burning emissions reconcile conflicting estimates of the post-2006 atmospheric methane budget

John R. Worden, A. Anthony Bloom, Sudhanshu Pandey, Zhe Jiang, Helen M. Worden, Thomas W. Walker, Sander Houweling, Thomas Röckmann

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

Several viable but conflicting explanations have been proposed to explain the recent textasciitilde8 p.p.b. per year increase in atmospheric methane after 2006, equivalent to net emissions increase of textasciitilde25 Tg CH4 per year. A concurrent increase in atmospheric ethane implicates a fossil source; a concurrent decrease in the heavy isotope content?of methane points toward a biogenic source, while other studies propose a decrease in the chemical sink (OH). Here we show that biomass burning emissions of methane decreased by 3.7 (textpm1.4) Tg CH4 per year from the 2001-2007 to the 2008-2014 time periods using satellite measurements of CO and CH4, nearly twice the decrease expected from prior estimates. After updating both the total and isotopic budgets for atmospheric methane with these revised biomass burning emissions (and assuming no change to the chemical sink), we find that fossil fuels contribute between 12-19 Tg CH4 per year to the recent atmospheric methane increase, thus reconciling the isotopic- and ethane-based results.
Original languageUndefined/Unknown
Article number2227
Pages (from-to)2227
Number of pages1
JournalNature Communications
Volume8
Issue number1
DOIs
Publication statusPublished - 2017

Funding

Competing interests: This research was funded through a NASA Carbon Cycle Science ROSES grant NNH13ZDA001N. The remaining authors declare no competing financial interests. This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. The work at Utrecht University is related to the program of the Netherlands Earth System Science Centre (NESSC), financially supported by the Ministry of Education, Culture and Science (OCW). The National Center for Atmospheric Research (NCAR) is sponsored by the National Science Foundation. The MOPITT and TES projects are supported by the National Aeronautics and Space Administration (NASA) Earth Observing System (EOS) Program. The MOPITT team also acknowledges support from the Canadian Space Agency (CSA), the Natural Sciences and Engineering Research Council (NSERC) and Environment Canada, along with the contributions of COMDEV and ABB BOMEM. Methane surface data were downloaded from the World Data Centre for Greenhouse Gases. We are very grateful to all the institutions and individuals who provide these surface data for researchers to use as these efforts are critical for carbon cycle science research; the following is hopefully an inclusive list of institutions and individuals, based on email response, who provide data that we use in this research: (1) NOAA, Boulder CO/Ed Dlugokencky, Laboratory for Earth Observations and Analyses, (2) ENEA, Palermo, Italy/Salvatore Piacentino, the CSIRO Flask Network/Paul Krum-mel, (3) Atmospheric Environment Division, Global Environment and Marine Department Japan Meteorological Agency/Atsushi Takizawa, and (4) Canadian Greenhouse Gas Measurement Program, Environment Canada/Doug Worthy. We would like to thank Dr. David Schimel of JPL for his helpful comments and feedback. We would like to thank the Stable Isotope Lab, CU-INSTAAR: James White, Bruce Vaughn, and Sylvia Michel for use of their data in this analysis.

FundersFunder number
National Science Foundation
National Aeronautics and Space AdministrationNNH13ZDA001N
Canadian Space Agency
Natural Sciences and Engineering Research Council of Canada
Environment Canada
Universiteit Utrecht
Ministerie van Onderwijs, Cultuur en Wetenschap
Netherlands Earth System Science Centre

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