Improved global wetland carbon isotopic signatures support post-2006 microbial methane emission increase

Youmi Oh, Qianlai Zhuang, Lisa R. Welp, Licheng Liu, Xin Lan, Sourish Basu, Edward J. Dlugokencky, Lori Bruhwiler, John B. Miller, Sylvia E. Michel, Stefan Schwietzke, Pieter Tans, Philippe Ciais, Jeffrey P. Chanton

Research output: Contribution to journalArticlepeer-review

14 Scopus citations

Abstract

Atmospheric concentrations of methane, a powerful greenhouse gas, have strongly increased since 2007. Measurements of stable carbon isotopes of methane can constrain emissions if the isotopic compositions are known; however, isotopic compositions of methane emissions from wetlands are poorly constrained despite their importance. Here, we use a process-based biogeochemistry model to calculate the stable carbon isotopic composition of global wetland methane emissions. We estimate a mean global signature of −61.3 ± 0.7‰ and find that tropical wetland emissions are enriched by ~11‰ relative to boreal wetlands. Our model shows improved resolution of regional, latitudinal and global variations in isotopic composition of wetland emissions. Atmospheric simulation scenarios with the improved wetland isotopic composition suggest that increases in atmospheric methane since 2007 are attributable to rising microbial emissions. Our findings substantially reduce uncertainty in the stable carbon isotopic composition of methane emissions from wetlands and improve understanding of the global methane budget.

Original languageEnglish (US)
Article number159
JournalCommunications Earth and Environment
Volume3
Issue number1
DOIs
StatePublished - Dec 2022

Bibliographical note

Funding Information:
This work was supported by NASA Earth and Space Science Fellowship Program (#80NSSC17K0368 P00001) and Interdisciplinary Research in Earth Science (#NNX17AK20G). We thank Carmody K. McCalley for providing data and John Mund for technical support.

Publisher Copyright:
© 2022, The Author(s).

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