Reconciling divergent estimates of oil and gas methane emissions

Details

• Journal Title:
  Proceedings of the National Academy of Science of the United States
• Personal Author:
  Zavala-Araiza, Daniel ; Lyon, David R. ; Alvarez, Ramón A. ; Davis, Kenneth J. ; Harriss, Robert ; Herndon, Scott C. ; Karion, Anna ; Kort, Eric Adam ; Lamb, Brian K. ; Lan, Xin ; Marchese, Anthony J. ; Pacala, Stephen W. ; Robinson, Allen L. ; Shepson, Paul B. ; Sweeney, Colm ; Talbot, Robert ; Townsend-Small, Amy ; Yacovitch, Tara I. ; Zimmerle, Daniel J. ; Hamburg, Steven P.
• NOAA Program & Office:
  OAR (Oceanic and Atmospheric Research) ; GMD (Global Monitoring Division)
• Description:
  Published estimates of methane emissions from atmospheric data (top-down approaches) exceed those from source-based inventories (bottom-up approaches), leading to conflicting claims about the climate implications of fuel switching from coal or petroleum to natural gas. Based on data from a coordinated campaign in the Barnett Shale oil and gas-producing region of Texas, we find that top-down and bottom-up estimates of both total and fossil methane emissions agree within statistical confidence intervals (relative differences are 10% for fossil methane and 0.1% for total methane). We reduced uncertainty in top-down estimates by using repeated mass balance measurements, as well as ethane as a fingerprint for source attribution. Similarly, our bottom-up estimate incorporates a more complete count of facilities than past inventories, which omitted a significant number of major sources, and more effectively accounts for the influence of large emission sources using a statistical estimator that integrates observations from multiple ground-based measurement datasets. Two percent of oil and gas facilities in the Barnett accounts for half of methane emissions at any given time, and high-emitting facilities appear to be spatiotemporally variable. Measured oil and gas methane emissions are 90% larger than estimates based on the US Environmental Protection Agency's Greenhouse Gas Inventory and correspond to 1.5% of natural gas production. This rate of methane loss increases the 20-y climate impacts of natural gas consumed in the region by roughly 50%.
• Keywords:
  Emissions Methane
• Source:
  Proc Natl Acad Sci U S A. 2015 Dec 22; 112(51): 15597-15602.
• DOI:
  https://doi.org/10.1073/pnas.1522126112
• Pubmed Central ID:
  PMC4697433
• Document Type:
  Journal Article
• Rights Information:
  Other
• Compliance:
  PMC
• Main Document Checksum:
  urn:sha-512:84bfd98998b15dcc093097003368a36d44cb684fb7ea02583beca2c35978d379b9e3a858a45a7fc5d4356592bab9a2074507864baf1f951574185ea986fb2436
• Download URL:
  https://repository.library.noaa.gov/view/noaa/24386/noaa_24386_DS1.pdf
• File Type:
  [PDF - 906.05 KB ]