Atmospheric data analyzed in “Microbial driver of 2006 – 2023 CH4 growth indicated by trends in atmospheric 𝛿D-CH4 and 𝛿13C-CH4”, PNAS

Atmospheric data analyzed in “Microbial driver of 2006 – 2023 CH₄ growth indicated by trends in atmospheric 𝛿D-CH₄ and 𝛿¹³C-CH₄”, PNAS

Ben Riddell-Young^1,2; Sylvia Englund Michel^3,4; Xin Lan^1,2; Pieter Tans³; Thomas Röckmann⁵; Bibhasvata Dasgupta⁵; Youmi Oh^1,2; Lori Bruhwiler^1,2; Ryo Fujita⁶; Taku Umezawa^7,8; Shinji Morimoto⁷; John Miller²

¹ Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, CO, 80309, USA

² Global Monitoring Laboratory, National Oceanic and Atmospheric Administration, Boulder, CO, 80205, USA

³ Institute of Arctic and Alpine Research, University of Colorado, Boulder, CO, 80303, USA

⁴ Department of Atmospheric and Oceanic Sciences, University of Colorado, Boulder, CO, 80303, USA

⁵ Institute for Marine and Atmospheric research Utrecht, Utrecht University, The Netherlands

⁶ Meteorological Research Institute, Japan Meteorological Agency, Tsukuba, Japan

⁷ Tohoku University, Sendai, Japan

⁸ National Institute for Environmental Studies, Tsukuba, Japan

Corresponding Author: Ben Riddell-Young

E: ben.riddell-young@colorado.edu

Abstract:

This paper investigates the global annual average record of atmospheric methane (CH₄) and the stable isotopic composition of atmospheric CH₄ (𝛿D-CH₄ and 𝛿¹³C-CH₄). Atmospheric CH₄ and 𝛿¹³C-CH₄ global means are determined from the NOAA Global Monitoring Laboratories Global Greenhouse Gas Reference Network. Discrete data and descriptions of sampling methods are available on the NOAA GML website.

The 2005 to 2023 global mean atmospheric 𝛿D-CH₄ was determined using a compilation of discrete measurements from several different laboratories at sampling sites around the world (see below). The data are presented on their original laboratory-specific calibration scales and are from sites that receive well-mixed air that is minimally influenced by local source, which are known as marine boundary layer reference sites. In the paper, the data were harmonized to the MPI-BGC scale using established laboratory offsets from Umezawa et al., 2018 (https://doi.org/10.5194/amt-11-1207-2018) and a recent intercomparison between INSTAAR and MPI-BGC. Alternatively, the data can be harmonized using a more recent estimate of laboratory offsets from Dasgupta et al., 2025 (https://doi.org/10.5194/egusphere-2025-2439), which differs slightly. Refer to Table S1 in the paper for offset values and uncertainties used.

All atmospheric data included in the paper are available here. If you would like to use the δD-CH₄ data in publication, please contact benjamin.riddell-young@noaa.gov. If you would like to use the δ¹³C-CH₄ data in publication, please contact sylvia.michel@colorado.edu. If you would like to use the CH₄ data in publication, please also contact xin.lan@noaa.gov. If you would like to use the isotopic data from MPI, NIWA, or TU/NIPR in publications, please contact the data providers listed next to the data below.

Globally averaged data files (Figure 1 in manuscript):

• Global annual average 𝛿D-CH₄, global annual average uncertainty, trend, and trend uncertainty since 2005: ch3d_glob_mean_unc.xlsx
• Global annual average 𝛿¹³C-CH₄, global annual average uncertainty, trend, and trend uncertainty since 1999: ch4c13_glob_mean_unc.xlsx

𝛿D-CH₄ site data files:

• INSTAAR Stable Isotope Laboratory Data:
  • Folder name: INSTAAR_ch3d
  • The folder contains atmospheric 𝛿D-CH₄ measurements from the following sampling sites:
    • Alert, Canada (ALT): alt.ch4h2.txt
    • Barrow Atmospheric Baseline Observatory, Alaska, USA (BRW): brw.ch4h2.txt
    • Cold Bay, Alaska, USA (CBA): cba.ch4h2.txt
    • Cape Grim, Tasmania, Australia (CGO): cgo.ch4h2.txt
    • Cape Kumukahi, Hawaii, USA (KUM): kum.ch4h2.txt
    • Mace Head, Ireland (MHD): mhd.ch4h2.txt
    • Tutuila, American Samoa (SMO): smo.ch4h2.txt
    • South Pole, Antarctica (SPO): spo.ch4h2.txt
    • Ny-Alesund, Svalbard, Norway (ZEP): zep. ch4h2.txt
  • Dataset Contact: Sylvia Michel: michel@colorado.edu
• Max Planck Institute for Biogeochemistry (MPI-BGC) Data:
  • Folder name: MPI-BGC_ch3d
  • The folder contains atmospheric 𝛿D-CH₄ measurements from the following sampling sites:
    • Alert, Canada (ALT): Flasks_ALT_dH2(CH4)_v2025.1.txt
    • Cape Verde Atmospheric Observatory, Cape Verde (CVO): Flasks_CVO_dH2(CH4)_v2025.1.txt
    • Neumayer Station, Antarctica (GVN/NMY): Flasks_GVN_dH2(CH4)_v2025.1.txt
    • Gobabeb Station, Namibia (NMB): Flasks_NMB_dH2(CH4)_v2025.1.txt
    • Shetland Islands, United Kingdom (SIS): Flasks_SIS_dH2(CH4)_v2025.1.txt
    • Villium Research Station, Greenland (VRS/SNO): Flasks_SNO_dH2(CH4)_v2025.1.txt
    • Zotina Tall Tower Observatory, Siberia, Russia (ZOT): Flasks_ZOT_dH2(CH4)_v2025.1.txt
  • Public repository link: https://www.edmond.mpg.de/dataset.xhtml?persistentId=doi:10.17617/3.V2EXHD
  • Dataset contact: Dr. Heiko Moossen (moossen@bgc-jena.mpg.de)
• Utrecht University’s Institute for Marine and Atmospheric Research (UU/IMAU) Data:
  • Folder name: UU-IMAU_ch3d
  • The folder contains atmospheric 𝛿D-CH₄ measurements from the following sampling sites:
    • Neumayer Station, Antarctica (GVN):
    • Ny-Alesund, Svalbard, Norway (ZEP):
  • Dataset contact: Dr. Thomas Röckmann (rockmann@uu.nl)
• Tohoku University and the National Institute for Polar Research (TU/NIPR) Data:
  • Folder name: TU-NIPR_ch3d
  • The folder contains atmospheric 𝛿D-CH₄ measurements from the following sampling sites:
    • Nyvolesund Station, Norway (NYA):
    • Syowa Station, Antarctica (SYO): ch3d_syo_TU-NIPR.txt
  • Dataset contact: Dr. Shinji Morimoto: (mon@tohoku.ac.jp)

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