Articles | Volume 22, issue 23
Research article
 | Highlight paper
05 Dec 2022
Research article | Highlight paper |  | 05 Dec 2022

Estimating emissions of methane consistent with atmospheric measurements of methane and δ13C of methane

Sourish Basu, Xin Lan, Edward Dlugokencky, Sylvia Michel, Stefan Schwietzke, John B. Miller, Lori Bruhwiler, Youmi Oh, Pieter P. Tans, Francesco Apadula, Luciana V. Gatti, Armin Jordan, Jaroslaw Necki, Motoki Sasakawa, Shinji Morimoto, Tatiana Di Iorio, Haeyoung Lee, Jgor Arduini, and Giovanni Manca

Data sets

Database of CH₄ and δ¹³CH₄ observations assimilated Xin Lan, Edward Dlugokencky, Sylvia Englund Michel, Sourish Basu, Kenneth Schuldt, John Mund, Shuji Aoki, Alcide "Giorgio" di Sarra, Alex Vermeulen, Arlyn Andrews, Armin Jordan, ,Bianca Baier, Casper Labuschagne, Catherine Lund Myhre, Colm Sweeney, Dagmar Kubistin, Dan Smale, Doug Worthy, Emilio Cuevas, Francesco Apadula, Gordon Brailsford, Haeyoung Lee, Heiko Moosen, Hinrich Schaefer, Hsiang Jui, Jaroslaw Necki, Jgor Arduini, John Miller, John Moncrieff, Juha Hatakka, Karin Uhse, Kathryn McKain, Laszlo Haszpra, Luciana Gatti, Ludwig Ries, Martin Steinbacher, Martina Schmidt, Michel Ramonet, Mikhail Arshinov, Motoki Sasakawa, Nina Paramonova, Peter Bergamaschi, Ray Langenfelds, Seung-Yeon Kim, Shinji Morimoto, Shinya Takatsuji, Sylvia Nichol, Taku Umezawa, Tatiana Di Iorio, Teruo Kawasaki

Model code and software

TM5 4DVAR model code Sourish Basu, Arjo Segers, Maarten Krol and other TM5 4DVAR developers

Executive editor
Methane is a potent greenhouse gas and an important sink of atmospheric OH radicals, which determine the global atmospheric oxidation capacity. CH4 has increased since pre-industrial times until the year 2000, after which its global concentration has remained relatively stable. Since 2007, it is rapidly increasing again for reasons that are not well understood. The current paper analyses source specific methane emissions that are likely responsible for the recent increase. Global CH4 sources are determined using variational inversion based on measurements of methane and its isotope signatures (δ13C). This latter provide better constraints on the contributions of microbial and fossil fuel CH4 sources than the concentrations alone. The analysis points to a more strongly increasing contribution of microbial sources since 2007 than predicted by previous assessments (Global Carbon Project). These findings have the potential to lead to a major reassessment of the global methane budget.
Short summary
Atmospheric methane (CH4) has been growing steadily since 2007 for reasons that are not well understood. Here we determine sources of methane using a technique informed by atmospheric measurements of CH4 and its isotopologue 13CH4. Measurements of 13CH4 provide for better separation of microbial, fossil, and fire sources of methane than CH4 measurements alone. Compared to previous assessments such as the Global Carbon Project, we find a larger microbial contribution to the post-2007 increase.
Final-revised paper