Global Gas Geochemistry Inventory 2017

A new version of this database is now available at https://doi.org/10.15138/qn55-e011

Global Inventory of Gas Geochemistry Data from Fossil Fuel, Microbial and Biomass Burning Sources, Version 2017

Authors

• Sherwood, O.A., University of Colorado/INSTAAR *
• Schwietzke, S., University of Colorado/CIRES, NOAA/ESRL/GMD
• Arling, V.A., University of Colorado/CIRES, NOAA/ESRL/GMD
• Etiope, G., Istituto Nazionale di Geofisica e Vulcanologia

* corresponding author. Email: owen.sherwood@colorado.edu

https://www.earth-syst-sci-data.net/9/639/2017/

Abstract (from accompanying Earth Systems Science Data journal article):

The concentration of atmospheric methane (CH₄) has more than doubled over the industrial era. To help constrain global and regional CH₄ budgets, inverse (top-down) models incorporate data on the concentration and stable carbon (δ¹³C) and hydrogen (δ²H) isotopic ratios of atmospheric CH₄. These models depend on accurate δ¹³C and δ²H end-member source signatures for each the main emissions categories. Compared with meticulous measurement and calibration of isotopic CH₄ in the atmosphere, there has been relatively little effort to characterize globally representative isotopic source signatures, particularly for fossil fuel sources, since the 1980s. Most global CH₄ budget models have so far relied on outdated source signature values derived from globally non-representative data. To correct this deficiency, we present a comprehensive, globally representative end-member database of the δ¹³C and δ²H of CH₄ from fossil fuel (conventional natural gas, shale gas and coal), modern microbial (wetlands, rice paddies, ruminants, termites, and landfills/waste) and biomass burning sources. Alkane and permanent gas molecular chemistry for fossil fuel categories are also included with the database. The database comprises 10,706 samples (8,732 fossil fuel, 1972 non-fossil) from 190 published references. Mean (unweighted) δ¹³C signatures for fossil fuel CH₄ are significantly lighter than values commonly used in CH₄ budget models, thus highlighting potential under-estimation of fossil fuel CH₄ emissions in previous CH₄ budget models. This living database will be updated every 2-3 years to provide the atmospheric modeling community with the most complete CH₄ source signature data possible.

Version Information:

This 2017 version of the gas geochemistry database supersedes an earlier version (Sherwood, O. A., Schwietzke, S. S., Arling, V. A., and Etiope, G.: Global Inventory of Fossil and Non-fossil Methane δ¹³C Source Signature Measurements for Improved Atmospheric Modeling. Available at: https://doi.org/10.15138/G37P4D, 2016).
The following updates have been made to the 2017 version:

• Fossil Fuel Data: Concentrations of permanent gases and C₁ to C₆ alkanes added
• Fossil Fuel Data: δ¹³C of C₂+ alkanes added to fossil fuel data
• Fossil Fuel Data: δ²H of CH₄ and C2+ alkanes added to fossil fuel data
• Non-Fossil Data: Corrected sample counts and uncertainty type for Cerling et al. (1997)
• Non-Fossil Data: Corrected sample counts for Chanton and Martens (1988)
• Non-Fossil Data: Corrected sample location (Illinois, USA) for Rust (1981)
• Non-Fossil Data: From Whalen et al. (1987), deleted data for termites as abstract does not distriguish between termites and cattle. Added data for rice fields.
• Non-Fossil Data: Added data on δ²H from termites from Whalen et al. (1989)

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