Defratyka, S M; Fernandez, J M; Adnew, G A; Dong, G; Douglas, P M J; Eldridge, D L; Etiope, G; Giunta, T; Haghnegahdar, M A; Hristov, A N; Hultquist, N; Vadillo, I; Jautzy, J; Kim, J-H; Labidi, J; Lalk, E; Leavitt, W; Li, J; Lin, L-H; Liu, J; Ojeda, L; Ono, S; Rhim, J H; Röckmann, T; Sherwood Lollar, B; Sivan, M; Sun, J; Ventura, G T; Wang, D T; Young, E D; Zhang, N; Arnold, T (2025) Global inventory of doubly substituted isotopologues of methane (Δ 13 CH 3 D and Δ 12 CH 2 D 2 ). Earth System Science Data, 17 (12). pp. 6889-6910. ISSN 1866-3516

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Abstract

Understanding why methane (CH4) is currently rising in the atmosphere is under scrutiny owing to recent years having some of the highest annual growth rates witnessed in decades. Methane isotopologue ratios containing the doubly substituted isotopologues (13CH3D and 12CH2D2), also termed ‘clumped’ isotopologues, have potential to help bring further direct evidence for studying the reasons for this growth. In this work, we summarise the state of doubly substituted CH4 measurement research, with an emphasis on compiling results of all relevant work to aid development of the inputs to atmospheric modelling studies. The database comprises 1241 records compiled from the literature over the last ten years (doi.org/10.5285/f90fc5b05bb4450f87e89b5f86038346). For field samples, 43% of records come from natural gas. Lakes samples contribute 70% of microbial field samples. There is limited representation of samples coming from wetlands and agriculture sources. So far, no samples for measurement of Δ13CH3D and Δ12CH2D2 were collected from anthropogenic waste sources. Laboratory experiments were mostly focused on methanogenesis or anaerobic and aerobic CH4 oxidation, with insignificant contribution of studies on OH and Cl oxidation. The range of Δ13CH3D and Δ12CH2D2 measured in these studies highlights their potential to improve our understanding of atmospheric CH4. This work also provides an overview of the major gaps in measurements and where further studies should be focussed to enable the greatest immediate impact on understanding global CH4.

Item Type:	Article
Subjects:	Environmental Measurement > Atmospheric Science, Emission and Security
Divisions:	Atmospheric Environmental Sciences
Identification number/DOI:	10.5194/essd-17-6889-2025
Last Modified:	22 Jun 2026 13:04
URI:	https://eprintspublications.npl.co.uk/id/eprint/10469