Assessing fossil fuel CO2 emissions in California using atmospheric observations and models

H. Graven, M. L. Fischer, T. Lueker, S. Jeong, T. P. Guilderson, R. F. Keeling, R. Bambha, K. Brophy, W. Callahan, X. Cui, C. Frankenberg, K. R. Gurney, B. W. Lafranchi, S. J. Lehman, H. Michelsen, J. B. Miller, S. Newman, W. Paplawsky, N. C. Parazoo, C. SloopS. J. Walker

Research output: Contribution to journalArticlepeer-review

30 Scopus citations


Analysis systems incorporating atmospheric observations could provide a powerful tool for validating fossil fuel CO2 (ffCO2) emissions reported for individual regions, provided that fossil fuel sources can be separated from other CO2 sources or sinks and atmospheric transport can be accurately accounted for. We quantified ffCO2 by measuring radiocarbon (14C) in CO2, an accurate fossil-carbon tracer, at nine observation sites in California for three months in 2014-15. There is strong agreement between the measurements and ffCO2 simulated using a high-resolution atmospheric model and a spatiotemporally-resolved fossil fuel flux estimate. Inverse estimates of total in-state ffCO2 emissions are consistent with the California Air Resources Board's reported ffCO2 emissions, providing tentative validation of California's reported ffCO2 emissions in 2014-15. Continuing this prototype analysis system could provide critical independent evaluation of reported ffCO2 emissions and emissions reductions in California, and the system could be expanded to other, more data-poor regions.

Original languageEnglish (US)
Article number065007
JournalEnvironmental Research Letters
Issue number6
StatePublished - Jun 2018
Externally publishedYes


  • California
  • atmospheric inversion
  • carbon dioxide
  • fossil fuel emissions
  • radiocarbon

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • General Environmental Science
  • Public Health, Environmental and Occupational Health


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