They’re vast expanses that can be as big as towns: open landfills where household waste ends up, whether it’s vegetable scraps or old appliances. These landfills also belch methane, a powerful, planet-warming gas, on average at almost three times the rate reported to federal regulators, according to a study published Thursday in the journal Science. The study measured methane emissions at about 20 percent of about 1,200 large, operating landfills in the United States. It adds to a growing body of evidence that landfills are a significant driver of climate change, said Riley Duren, founder of the public-private partnership Carbon Mapper, who took part in the study. “We’ve largely been in the dark, as a society, about actual emissions from landfills,” said Mr. Duren, a former NASA engineer and scientist.

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Persons: Riley Duren, “ We’ve, ” Organizations: Carbon, NASA Locations: United States, Duren