Microbial driver of 2006-2023 CH4 growth indicated by trends in atmospheric δD-CH4 and δ13C-CH4

• 成果类型: Article
• 署名作者: Riddell, Ben; Michel, Sylvia Englund; Lan, Xin; Tans, Pieter; Rockmann, Thomas; Dasgupta, Bibhasvata; Oh, Youmi; Bruhwiler, Lori M. P.; Fujita, Ryo; Umezawa, Taku; Morimoto, Shinji; Miller, John B.
• 署名单位: University of Colorado System; University of Colorado Boulder; National Oceanic Atmospheric Admin (NOAA) - USA; University of Colorado System; University of Colorado Boulder; University of Colorado System; University of Colorado Boulder; Utrecht University; Japan Meteorological Agency; Meteorological Research Institute - Japan; Tohoku University; National Institute for Environmental Studies - Japan
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.2516543122
• 发表日期: 2025-12-16
• 页码: e2516543122
• 关键词: methane; isotope geochemistry; emissions; greenhouse gases; climate change; methane emissions; isotopic composition; fossil-fuel; GLOBAL INVENTORY; carbon-dioxide; DELTA-D; database; WETLAND; ratios; variability

摘要

Methane (CH4) is the second most important greenhouse gas and has been rising following a brief period of stabilization from 1999 to 2006. Determining the cause of this rise is critical for reducing emissions and predicting future climate sensitivity. The carbon and hydrogen stable isotopic composition of atmospheric CH4 is controlled by variability in isotopically distinguishable emission categories and fractionating sink processes. While most studies using atmospheric S13C-CH4 data suggest a dominantly microbial source for recent CH4 growth, this understanding is not uniform, and uncertainties remain [S. Schwietzke et al., Nature 538, 88-91 (2016), S. Basu et al., Atmos. Chem. Phys. 22, 15351-15377 (2022), J. Thanwerdas, M. Saunois, A. Berchet, I. Pison, P. Bousquet, Atmos. Chem. Phys. 24, 2129-2167 (2024)]. Here, we present a harmonized global measurement record of atmospheric SD-CH4 and estimate emissions from 1999 to 2022 with global isotope mass balance calculations using both carbon and hydrogen isotopic ratios. We conduct thorough uncertainty analyses to separate absolute magnitude and emission trend uncertainties and find with high confidence that trends in S13C-CH4 and SD-CH4 observations are both consistent with an entirely microbial emission driver of the post-2006 CH4 rise, while fossil fuel emissions have remained relatively stable.