Research finds EPA underestimates methane emissions from oil and gas production.
The Environmental Protection Agency (EPA) is underestimating methane emissions from oil and gas production in its annual Inventory of U.S. Greenhouse Gas Emissions and Sinks, according to new research from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS). The research team found 90 percent higher emissions from oil production and 50 percent higher emissions for natural gas production than EPA estimated in its latest inventory.
The paper is published in the journal Atmospheric Chemistry and Physics.
The research team, led by Joannes Maasakkers, a former graduate student at SEAS, developed a method to trace and map total emissions from satellite data to their source on the ground.
“This is the first country-wide evaluation of the emissions that the EPA reports to the United Nations Framework Convention on Climate Change (UNFCCC),” said Maasakkers, who is currently a scientist at the SRON Netherlands Institute for Space Research.
Currently, the EPA only reports total national emissions to the UNFCC. In previous research, Maasakkers and his collaborators, including Daniel Jacob, the Vasco McCoy Family Professor of Atmospheric Chemistry and Environmental Engineering at SEAS, worked with the EPA to map regional emissions of methane from different sources in the US. That level of detail was used to simulate how methane moves through the atmosphere.
In this paper, the researchers compared those simulations to satellite observations from 2010-2015. Using a transport model, they were able to trace the path of emissions from the atmosphere back to the ground and identify areas across the US where the observations and simulations didn’t match up.
“When we look at emissions from space, we can only see how total emissions from an area should be scaled up or down, but we don’t know the source responsible for those emissions,” said Maasakkers. “Because we spent so much time with the EPA figuring out where these different emissions occur, we could use our transport model to go back and figure out what sources are responsible for those under- or over-estimations in the national total.”
The biggest discrepancy was in emissions from oil and natural gas production.