An Unexpected Seasonal Cycle in U.S. Oil and Gas Methane Emissions
Accurate quantification of methane (CH<sub>4</sub>) emissions is essential for understanding changes in its atmospheric abundance. Atmospheric observations can supply independent emission information that complements and strengthens inventory-based estimates. In this study, we quantified annual and monthly U.S. CH<sub>4</sub> emissions in 2008-2021 using inverse modeling of ground and airborne measurements at sites across the U.S. with 10-12 km atmospheric transport simulations. While the magnitude, spatial distribution, and trend of the estimated CH<sub>4</sub> emissions align with some previous studies, our results reveal an unexpected seasonal cycle in CH<sub>4</sub> emissions from the oil and gas sector, where wintertime emissions are about 40 (20-50, 2σ) % higher than summertime. This seasonality is supported by methane and propane measurements at these same sites, as well as methane isotope measurements made from an independent aircraft campaign over the U.S. Although the exact cause of this emission seasonality is unclear, its spatial distribution indicates that the enhanced CH<sub>4</sub> emissions are primarily from natural gas production regions, and to a lesser extent, from natural gas consumption in winter.
Authors
- Monica Madronich
- Lei Hu (ORCID: https://orcid.org/0000-0002-5624-3832)
- John Bharat Miller (ORCID: https://orcid.org/0000-0001-8630-1610)
- N. L. Miles (ORCID: https://orcid.org/0000-0003-4266-2726)
- K. J. Davis (ORCID: https://orcid.org/0000-0002-1992-8381)
- Colm Sweeney (ORCID: https://orcid.org/0000-0002-4517-0797)
- A. E. Andrews (ORCID: https://orcid.org/0000-0002-8552-3999)
- Scot M. Miller (ORCID: https://orcid.org/0000-0003-4462-8126)
- Marikate Mountain (ORCID: https://orcid.org/0000-0002-1169-1957)
- Sylvia Michel (ORCID: https://orcid.org/0000-0002-5651-1163)
- Youmi Oh (ORCID: https://orcid.org/0000-0002-4685-0567)
- Kathryn McKain (ORCID: https://orcid.org/0000-0002-8323-5758)
- Lori Bruhwiler (ORCID: https://orcid.org/0000-0002-3554-9250)
- Thomas Mefford (ORCID: https://orcid.org/0000-0002-9523-6731)
- Xin Lan (ORCID: https://orcid.org/0000-0001-6327-6950)
- Sergio Ibarra Espinosa
- S. A. Montzka (ORCID: https://orcid.org/0000-0002-9396-0400)
- Andy Crotwell
- Sander Houwelling
Institutions
- Pennsylvania State University (US)
- National Oceanic and Atmospheric Administration (US)
- Johns Hopkins University (US)
- Cooperative Institute for Research in Environmental Sciences (US)
- Institute of Arctic and Alpine Research (US)
- University of Colorado Boulder (US)
- University of Colorado System (US)
- Atmospheric and Environmental Research (US)
- Vrije Universiteit Amsterdam (NL)
Publication Details
- Journal
- Environmental Science & Technology
- Published
- 2025-05-14
- DOI
- https://doi.org/10.1021/acs.est.4c14090
- Citations
- 7
- Primary Topic
- Atmospheric and Environmental Gas Dynamics
- Type
- article
- Field-Weighted Citation Impact
- 7.74
Funders
- Climate Program Office