Are gassy cattle a bigger problem than US government thought?
Cattle generate twice as much methane as the EPA supposed, according to a new report. The study's findings may also change assumptions about the safety of extracting natural gas, which consists primarily of methane.
The gassy rumblings of ruminating cattle, along with the hisses and sloshes as natural gas is extracted, refined, and transported to communities across the United States, may release 50 percent more methane into the atmosphere than the government had estimated, according to a report published Monday by Harvard University scientists. Because methane (CH4) is a potent greenhouse gas, the new findings could tilt the international debate on the safety of natural gas, which the White House has promoted as a "clean energy" source responsible for a domestic manufacturing boom.Skip to next paragraph
Fabien Tepper writes for the Monitor's science desk and weekly magazine. She holds a master's degree in Animals and Public Policy from Tufts University, and a bachelor's degree in art from Swarthmore College.
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The nearly 90 million cattle who spend their days in US feedlots are the country's largest source of methane from anthropogenic (human-caused) emissions, the Environmental Protection Agency estimates. But the new report finds that ruminant animals generate twice as much methane as the EPA supposed. In Texas, Oklahoma, and Kansas, anthropogenic methane emissions from all sources were 2.7 times greater than believed, making up 24 percent of the nation's emissions, found the study, which was published in the Proceedings of the National Academy of Sciences.
The report comes on the heels of a decision by the EPA to reduce its estimates – by 25 percent to 30 percent – of the atmospheric carbon released by the natural-gas industry.
"These results cast doubt on the EPA's recent decision," wrote the researchers for the report. "Overall, we conclude that methane emissions associated with both the animal husbandry and fossil fuel industries have larger greenhouse gas impacts than indicated by existing inventories."
The MIT Technology Review described how the study might change the perceptions of different fossil fuels:
"At stake is whether switching from coal to natural gas can provide a net benefit in reducing greenhouse-gas emissions. Burning natural gas releases about half as much carbon dioxide as burning coal. But that benefit could be offset by leaks of methane, the primary component of natural gas."
President Obama remains a strong supporter of the natural-gas industry, but he has begun discussing it in more measured terms. In his 2012 State of the Union address, he praised the industry's cleanliness and economic promise, which he said was "proving that we don't have to choose between our environment and our economy." But his 2013 Economic Report included some reservations:
"Measuring fugitive methane emissions from the U.S. natural gas supply chain and, more generally, understanding the potential impacts of natural gas development on water quality, air quality, ecosystems, and induced seismicity, are critical to understanding the impact on the environment of the increasing use of natural gas."