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Using high frequency observations of δ13C-CH4 and δ2H-CH4 and uncertain regional isotopic signatures to estimate sources of UK methane emissions

Ramsden, Alice E. ; Ganesan, Anita L. ; Rigby, Matthew ; Rennick, Chris ; Arnold, Tim LU orcid ; Safi, Emmal ; Chung, Edward ; Kikaj, Dafina ; Yeo, Cameron and Lowry, Dave , et al. (2026) In Atmospheric Chemistry and Physics 26(15). p.11421-11448
Abstract
Methane is emitted from a range of anthropogenic and natural sources, and identifying these sources is important for emissions monitoring and mitigation. Different sources emit methane with different isotopic signatures. However, these signatures can vary spatially and temporally and are often not well understood. Top-down inverse methods can be used with measurements of methane mole fractions to estimate total emissions of methane from all sources. Here, we present an inverse system for concurrently estimating regional fossil-fuel (FF) and non-fossil-fuel (non-FF) emissions, using isotope ratio observations and considering uncertainty in the isotopic signatures. This method is highly adaptable and could be used to estimate emissions from... (More)
Methane is emitted from a range of anthropogenic and natural sources, and identifying these sources is important for emissions monitoring and mitigation. Different sources emit methane with different isotopic signatures. However, these signatures can vary spatially and temporally and are often not well understood. Top-down inverse methods can be used with measurements of methane mole fractions to estimate total emissions of methane from all sources. Here, we present an inverse system for concurrently estimating regional fossil-fuel (FF) and non-fossil-fuel (non-FF) emissions, using isotope ratio observations and considering uncertainty in the isotopic signatures. This method is highly adaptable and could be used to estimate emissions from any number of sources. Synthetic data tests with this method show that this inverse system can accurately estimate FF and non-FF methane emissions across the UK, when isotopic source signatures are fixed at known values. However, emissions estimation becomes less accurate when source signature uncertainties are increased to over approximately 50 % of their likely ranges. In a real-world test of this method, we estimated south-east UK FF and non-FF emissions using high-frequency δ13C-CH4 and δ2H-CH4 observations from one UK site, with source signature uncertainties reflecting our current understanding of these values. Results show only a limited impact on emissions uncertainty and magnitude, when compared with a methane-only inversion. This suggests that both an expansion of the UK network of isotope ratio observations and an improved understanding of isotopic signatures is required for this method to be effective in estimating UK FF and non-FF methane emissions with reduced uncertainty compared to traditional inverse methods. (Less)
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organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Atmospheric Chemistry and Physics
volume
26
issue
15
pages
11421 - 11448
publisher
Copernicus GmbH
ISSN
1680-7324
DOI
10.5194/acp-26-11421-2026
language
English
LU publication?
yes
id
184dbe17-cb6a-423c-92dd-57448c5e2c4e
date added to LUP
2026-08-17 10:52:21
date last changed
2026-08-17 11:58:33
@article{184dbe17-cb6a-423c-92dd-57448c5e2c4e,
  abstract     = {{Methane is emitted from a range of anthropogenic and natural sources, and identifying these sources is important for emissions monitoring and mitigation. Different sources emit methane with different isotopic signatures. However, these signatures can vary spatially and temporally and are often not well understood. Top-down inverse methods can be used with measurements of methane mole fractions to estimate total emissions of methane from all sources. Here, we present an inverse system for concurrently estimating regional fossil-fuel (FF) and non-fossil-fuel (non-FF) emissions, using isotope ratio observations and considering uncertainty in the isotopic signatures. This method is highly adaptable and could be used to estimate emissions from any number of sources. Synthetic data tests with this method show that this inverse system can accurately estimate FF and non-FF methane emissions across the UK, when isotopic source signatures are fixed at known values. However, emissions estimation becomes less accurate when source signature uncertainties are increased to over approximately 50 % of their likely ranges. In a real-world test of this method, we estimated south-east UK FF and non-FF emissions using high-frequency δ13C-CH4 and δ2H-CH4 observations from one UK site, with source signature uncertainties reflecting our current understanding of these values. Results show only a limited impact on emissions uncertainty and magnitude, when compared with a methane-only inversion. This suggests that both an expansion of the UK network of isotope ratio observations and an improved understanding of isotopic signatures is required for this method to be effective in estimating UK FF and non-FF methane emissions with reduced uncertainty compared to traditional inverse methods.}},
  author       = {{Ramsden, Alice E. and Ganesan, Anita L. and Rigby, Matthew and Rennick, Chris and Arnold, Tim and Safi, Emmal and Chung, Edward and Kikaj, Dafina and Yeo, Cameron and Lowry, Dave and Levy, Pete and O'Doherty, Simon and Stanley, Kieran M. and Young, Dickon and Pitt, Joe and Martin, Damien and Lopez, Morgan and Ramonet, Michel and Forster, Grant L. and Frumau, Arnoud and Manning, Alistair J.}},
  issn         = {{1680-7324}},
  language     = {{eng}},
  number       = {{15}},
  pages        = {{11421--11448}},
  publisher    = {{Copernicus GmbH}},
  series       = {{Atmospheric Chemistry and Physics}},
  title        = {{Using high frequency observations of δ<sup>13</sup>C-CH<sub>4</sub> and δ<sup>2</sup>H-CH<sub>4</sub> and uncertain regional isotopic signatures to estimate sources of UK methane emissions}},
  url          = {{http://dx.doi.org/10.5194/acp-26-11421-2026}},
  doi          = {{10.5194/acp-26-11421-2026}},
  volume       = {{26}},
  year         = {{2026}},
}