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 language||English (US)|
|Journal||Communications Earth and Environment|
|State||Published - Dec 2022|
Bibliographical noteFunding 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.
© 2022, The Author(s).