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Spatially Resolved Isotopic Source Signatures of Wetland Methane Emissions
Author(s) -
Ganesan A. L.,
Stell A. C.,
Gedney N.,
ComynPlatt E.,
Hayman G.,
Rigby M.,
Poulter B.,
Hornibrook E. R. C.
Publication year - 2018
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2018gl077536
Subject(s) - wetland , environmental science , latitude , atmospheric sciences , ecosystem , isotopic signature , methane , atmospheric methane , geology , stable isotope ratio , ecology , physics , geodesy , quantum mechanics , biology
We present the first spatially resolved wetland δ 13 C(CH 4 ) source signature map based on data characterizing wetland ecosystems and demonstrate good agreement with wetland signatures derived from atmospheric observations. The source signature map resolves a latitudinal difference of ~10‰ between northern high‐latitude (mean −67.8‰) and tropical (mean −56.7‰) wetlands and shows significant regional variations on top of the latitudinal gradient. We assess the errors in inverse modeling studies aiming to separate CH 4 sources and sinks by comparing atmospheric δ 13 C(CH 4 ) derived using our spatially resolved map against the common assumption of globally uniform wetland δ 13 C(CH 4 ) signature. We find a larger interhemispheric gradient, a larger high‐latitude seasonal cycle, and smaller trend over the period 2000–2012. The implication is that erroneous CH 4 fluxes would be derived to compensate for the biases imposed by not utilizing spatially resolved signatures for the largest source of CH 4 emissions. These biases are significant when compared to the size of observed signals.