The Environmental Protection Agency (EPA) has underestimated methane emissions caused by oil and gas production by as much as 76%, according to research published on 29 June in the Journal of Geophysical Research: Atmospheres.
Researchers from The Pennsylvania State University collected data in the mid-Atlantic, mid-South, and central Midwest of the US from 2017 to 2019, tracking the movement of carbon dioxide, methane, and ethane within weather systems. They then studied ethane-to-methane ratios from oil and gas production basins and compared to them an EPA inventory of those emissions.
The assessment found emissions at levels between 48 and 76% higher than the EPA's estimates.
The researchers said they specifically analyzed ethane because it is only produced alongside certain methane emissions, whereas methane can be produced naturally and by landfills. Ethane also only lingers in the atmosphere for months at a time and offers a clearer picture of how recent the methane emissions occurred.
In a statement to The Hill, the EPA said its greenhouse gas emissions inventory methods are continually updated based on stakeholder feedback.
"Given the variability of practices and technologies across oil and gas systems and the occurrence of episodic events, it is possible that the EPA’s estimates do not include all methane emissions from abnormal events," an agency spokesperson said.