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the global methane budget 2000-2012The global methane (CH4) budget is becoming an increasingly important component for managing realistic pathways to mitigate climate change. This relevance, due to a shorter atmospheric lifetime and a stronger warming potential than carbon dioxide, is challenged by the still unexplained changes of atmospheric CH4 over the past decade. Emissions and concentrations of CH4 are continuing to increase, making CH4 the second most important human-induced greenhouse gas after carbon dioxide. Two major difficulties in reducing uncertainties come from the large variety of diffusive CH4 sources that overlap geographically, and from the destruction of CH4 by the very short-lived hydroxyl radical (OH). To address these difficulties, we have established a consortium of multi-disciplinary scientists under the umbrella of the Global Carbon Project to synthesize and stimulate research on the methane cycle, and producing regular (approximately biennial) updates of the global methane budget. This consortium includes atmospheric physicists and chemists, biogeochemists of surface and marine emissions, and socio-economists who study anthropogenic emissions. Following Kirschke et al. (2013), we propose here the first version of a living review paper that integrates results of top-down studies (exploiting atmospheric observations within an atmospheric inverse-modeling framework) and bottom-up models, inventories and data-driven approaches (including process-based models for estimating land surface emissions and atmospheric chemistry, and inventories for anthropogenic emissions, data-driven extrapolations).For the 2003-2012 decade, global methane emissions are estimated by top-down inversions at 558 TgCH4 yr(exp -1), range 540-568. About 60 of global emissions are anthropogenic (range 50-65%). Since 2010, the bottom-up global emission inventories have been closer to methane emissions in the most carbon-intensive Representative Concentrations Pathway (RCP8.5) and higher than all other RCP scenarios. Bottom-up approaches suggest larger global emissions (736 TgCH4 yr(exp -1), range 596-884) mostly because of larger natural emissions from individual sources such as inland waters, natural wetlands and geological sources. Considering the atmospheric constraints on the top-down budget, it is likely that some of the individual emissions reported by the bottom-up approaches are overestimated, leading to too large global emissions. Latitudinal data from top-down emissions indicate a predominance of tropical emissions (approximately 64% of the global budget, less than 30deg N) as compared to mid (approximately 32%, 30-60deg N) and high northern latitudes (approximately 4%, 60-90deg N). Top-down inversions consistently infer lower emissions in China (approximately 58 TgCH4 yr(exp -1), range 51-72, minus14% ) and higher emissions in Africa (86 TgCH4 yr(exp -1), range 73-108, plus 19% ) than bottom-up values used as prior estimates. Overall, uncertainties for anthropogenic emissions appear smaller than those from natural sources, and the uncertainties on source categories appear larger for top-down inversions than for bottom-up inventories and models. The most important source of uncertainty on the methane budget is attributable to emissions from wetland and other inland waters. We show that the wetland extent could contribute 30-40% on the estimated range for wetland emissions. Other priorities for improving the methane budget include the following: (i) the development of process-based models for inland-water emissions, (ii) the intensification of methane observations at local scale (flux measurements) to constrain bottom-up land surface models, and at regional scale (surface networks and satellites) to constrain top-down inversions, (iii) improvements in the estimation of atmospheric loss by OH, and (iv) improvements of the transport models integrated in top-down inversions. The data presented here can be downloaded from the Carbon Dioxide Information Analysis Center (http://doi.org/10.3334/CDIAC/GLOBAL_ METHANE_BUDGET_2016_V1.1) and the Global Carbon Project.
Document ID
20170005489
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Saunois, Marielle
(Laboratoire des Sciences du Climat et de l'Environnement Gif-sur-Yvette, France)
Bousquet, Philippe
(Laboratoire des Sciences du Climat et de l'Environnement Gif-sur-Yvette, France)
Poulter, Benjamin
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Peregon, Anna
(Laboratoire des Sciences du Climat et de l'Environnement Gif-sur-Yvette, France)
Ciais, Philippe
(Laboratoire des Sciences du Climat et de l'Environnement Gif-sur-Yvette, France)
Canadell, Josep G.
(Commonwealth Scientific and Industrial Research Organization Canberra, Australia)
Dlugokencky, Edward J.
(National Oceanic and Atmospheric Administration Highlands, NJ, United States)
Etiope, Giuseppe
(Istituto Nazionale di Geofisica e Vulcanologia Rome, Italy)
Bastviken, David
(Linkoeping Univ. Sweden)
Houweling, Sander
(SRON Space Research Organization Utrecht, Netherlands)
Janssens-Maenhout, Greet
(European Commission Joint Research Centre Ispra, Italy)
Tubiello, Francesco N.
(Food and Agriculture Organization of the United Nations Rome, Italy)
Castaldi, Simona
(Naples II Univ. Caserta, Italy)
Jackson, Robert B.
(Stanford Univ. Stanford, CA, United States)
Alexe, Mihai
(European Commission Joint Research Centre Ispra, Italy)
Arora, Vivek K.
(Environment and Climate Change Canada (ECCC) Victoria, British Columbia, Canada)
Beerling, David J.
(Sheffield Univ. United Kingdom)
Bergamaschi, Peter
(European Commission Joint Research Centre Ispra, Italy)
Blake, Donald R.
(California Univ. Irvine, CA, United States)
Brailsford, Gordon
(National Inst. of Water and Atmospheric Research Wellington, New Zealand)
Brovkin, Victor
(Max-Planck-Inst. fuer Meteorologie Hamburg, Germany)
Bruhwiler, Lori
(National Oceanic and Atmospheric Administration Highlands, NJ, United States)
Crevoisier, Cyril
(Laboratoire de Meteorologie Dynamique Palaiseau, France)
Crill, Patrick
(Bolin Centre for Climate Research Stockholm, Sweden)
Covey, Kristofer
(Yale Univ. New Haven, CT, United States)
Curry, Charles
(Victoria Univ. Victoria, British Columbia, Canada)
Frankenberg, Christian
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Gedney, Nicola
(Met Office Hadley Centre Wallingford, United Kingdom)
Hoglund-Isaksson, Lena
(Institute for Applied Systems Analysis Laxenburg, Austria)
Ishizawa, Misa
(National Inst. for Environmental Studies Ibaraki, Japan)
Ito, Akihiko
(National Inst. for Environmental Studies Ibaraki, Japan)
Joos, Fortunat
(Bern Univ. Bern, Switzerland)
Kim, Heon-Sook
(National Inst. for Environmental Studies Ibaraki, Japan)
Kleinen, Thomas
(Max-Planck-Inst. fuer Meteorologie Hamburg, Germany)
Krummel, Paul
(Commonwealth Scientific and Industrial Research Organization Aspendale, Australia)
Lamarque, Jean-Francois
(National Center for Atmospheric Research Boulder, CO, United States)
Langenfelds, Ray
(Commonwealth Scientific and Industrial Research Organization Aspendale, Australia)
Locatelli, Robin
(Laboratoire des Sciences du Climat et de l'Environnement Gif-sur-Yvette, France)
Machida, Toshinobu
(National Inst. for Environmental Studies Ibaraki, Japan)
Maksyutov, Shamil
(National Inst. for Environmental Studies Ibaraki, Japan)
McDonald, Kyle C.
(City Univ. of New York New York, NY, United States)
Marshall, Julia
(Max-Planck Inst. for Biogeochemistry Jena, Germany)
Melton, Joe R.
(Environment and Climate Change Canada (ECCC) Victoria, British Columbia, Canada)
Morino, Isam
(Met Office Hadley Centre Wallingford, United Kingdom)
Naik, Vaishali
(National Oceanic and Atmospheric Administration Princeton, NJ, United States)
O'Doherty, Simon
(Bristol Univ. United Kingdom)
Parmentier, Frans-Jan W.
(Lund Univ. Hospital Lund, Sweden)
Patra, Prabir K.
(Japan Marine Science and Technology Center Kanagawa, Japan)
Peng, Changhui
(Quebec Univ. Montreal, Quebec, Canada)
Peng, Shushi
(Laboratoire des Sciences du Climat et de l'Environnement Gif-sur-Yvette, France)
Peters, Glen P.
(Center for International Climate and Environmental Research (CICERO) Oslo, Norway)
Pison, Isabelle
(Laboratoire des Sciences du Climat et de l'Environnement Gif-sur-Yvette, France)
Prigent, Catherine
(Observatoire de Paris France)
Prinn, Ronald
(Massachusetts Inst. of Tech. Cambridge, MA, United States)
Ramonet, Michel
(Laboratoire des Sciences du Climat et de l'Environnement Gif-sur-Yvette, France)
Riley, William J.
(California Univ. Berkeley, CA, United States)
Saito, Makoto
(National Inst. for Environmental Studies Ibaraki, Japan)
Santini, Monia
(Euro-Mediterranean Center on Climate Change Lecce, Italy)
Schroeder, Ronny
(City Univ. of New York New York, NY, United States)
Simpson, Isobel J.
(California Univ. Irvine, CA, United States)
Spahni, Renato
(Bern Univ. Bern, Switzerland)
Steele, Paul
(Commonwealth Scientific and Industrial Research Organization Aspendale, Australia)
Takizawa, Atsushi
(Japan Meteorological Agency Tokyo, Japan)
Thornton, Brett F.
(Bolin Centre for Climate Research Stockholm, Sweden)
Tian, Hanqin
(Auburn Univ. AL, United States)
Tohjima, Yasunor
(National Inst. for Environmental Studies Ibaraki, Japan)
Viovy, Nicolas
(Laboratoire des Sciences du Climat et de l'Environnement Gif-sur-Yvette, France)
Voulgarakis, Aposolos
(Imperial Coll. of London London, United Kingdom)
van Weele, Michiel
(Royal Netherlands Meteorological Inst. De Bilt, Netherlands)
van der Werf, Guido R.
(Vrije Univ. Amsterdam, Netherlands)
Weiss, Ray
(Scripps Institution of Oceanography La Jolla, CA, United States)
Wiedinmyer, Christine
(Commonwealth Scientific and Industrial Research Organization Aspendale, Australia)
Wilton, David J.
(Sheffield Univ. United Kingdom)
Wiltshire, Andy
(Met Office Hadley Centre Exeter, United Kingdom)
Worthy, Doug
(Environment Canada Climate Change Canada (ECCC) Toronto, Ontario, Canada)
Wunch, Debra
(Toronto Univ. Ontario, Canada)
Xu, Xiyan
(California Univ. Berkeley, CA, United States)
Yoshida, Yukio
(National Inst. for Environmental Studies Ibaraki, Japan)
Zhang, Bowen
(Auburn Univ. AL, United States)
Zhang, Zhen
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Zhu, Qiuan
(Northwest A&F Univ. China)
Date Acquired
June 12, 2017
Publication Date
December 12, 2016
Publication Information
Publication: Earth System Science Data
Volume: 8
Issue: 2
Subject Category
Geophysics
Report/Patent Number
GSFC-E-DAA-TN43357
Funding Number(s)
CONTRACT_GRANT: NSF 1243232
CONTRACT_GRANT: NNX11AF16G
CONTRACT_GRANT: NNX14AO73G
CONTRACT_GRANT: NSF 1243220
CONTRACT_GRANT: NAG5-12669
CONTRACT_GRANT: NSF 1243232
CONTRACT_GRANT: NNX11AF17G
CONTRACT_GRANT: NNX14AF93G
CONTRACT_GRANT: NNX07AE89G
CONTRACT_GRANT: NNX11AF15G
CONTRACT_GRANT: DE-AC02-05CH11231
CONTRACT_GRANT: NNX07AE87G
CONTRACT_GRANT: NNX07AF09G
Distribution Limits
Public
Copyright
Other