US methane emissions exceed EPA’s data

Methane emissions in the US are markedly higher than what the US Environmental Protection Agency reports, according to multiple recent studies.

The most recent report comes from the Environmental Defense Fund (EDF), an advocacy group. It found that methane emissions from US oil and gas sources are four times as high as what the EPA reports and eight times as high as industry targets. The findings mirror other recent studies on methane emissions, in which other scientists found emission levels well above EPA values from sources including landfills, livestock, and coal mines.

Spurred by some of the findings, the Biden Administration released details July 23 about increased federal efforts to measure and reduce air pollution, including methane emissions.

Methane doesn’t last as long in the atmosphere as carbon dioxide does, but it has about 80 times the warming potential of CO₂ over a 20-year period and 28 times the potential over 100 years, the United Nations says. Methane emissions are responsible for about 30% of rising global temperatures, according to the International Energy Agency.

The EDF’s study looked specifically at onshore oil and gas production in the continental US. Using an airplane-based measurement system called MethaneAIR, scientists collected data from about 70% of the airspace above the areas of highest oil and gas production between June and October 2023. They then compared these numbers to data on greenhouse gas emissions that the oil and gas industry reported to the EPA for 2020, the most recent year for which methane emissions data are available, says EDF scientist Ritesh Gautam, who led the study.

The group found that methane emissions were the highest in the Permian Basin, an oil-rich area in southwest Texas and portions of New Mexico. Overall, it found the average emission intensity for the US to be eight times the goal set by oil and gas companies at the UN Climate Change Conference in 2023.

Many other recent studies on methane emissions also found that they are above what the EPA reports, Gautam says. But the exact amount depends on the sampling method and the resolution scientists are able to achieve. The MethaneAIR airplane collects data from an altitude of 12,000 m (40,000 ft), where the equipment can achieve better resolution than satellite methods do, he says.

An April study from NASA’s Jet Propulsion Laboratory (Atmos. Chem. Phys. 2024, DOI: 10.5194/acp-24-5069-2024) that used satellite data to measure emissions from several sources found that landfills emit about 50% more methane than what the EPA reports. The study found emissions to be 12% higher from oil and gas operations and 11% higher from livestock. But the NASA scientists found coal mining to emit 28% less methane than the EPA reports.

A study published in Science in March (DOI: 10.1126/science.adi7735) specifically measured landfills and found that, on average, they emit between 1.4 and 2.7 times as much methane as what operators report to the EPA.

New federal efforts to put a cork in methane emissions include the NASA-partnered Carbon Mapper Coalition satellite and an agreement between the US National Oceanic and Atmospheric Administration and United Airlines to use commercial planes to monitor methane and other pollutants.