Methane From Landfills Is a Big Driver of Climate Change, Study Says

An anonymous reader quotes a report from the New York Times: 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.

For the new study, scientists gathered data from airplane flyovers using a technology called imaging spectrometers designed to measure concentrations of methane in the air. Between 2018 and 2022, they flew planes over 250 sites across 18 states, about 20 percent of the nation's open landfills. At more than half the landfills they surveyed, researchers detected emissions hot spots, or sizable methane plumes that sometimes lasted months or years. That suggested something had gone awry at the site, like a big leak of trapped methane from layers of long-buried, decomposing trash, the researchers said.

'You can sometimes get decades of trash that's sitting under the landfill,' said Daniel H. Cusworth, a climate scientist at Carbon Mapper and the University of Arizona, who led the study. 'We call it a garbage lasagna.' Many landfills are fitted with specialized wells and pipes that collect the methane gas that seeps out of rotting garbage in order to either burn it off or sometimes to use it to generate electricity or heat. But those wells and pipes can leak. The researchers said pinpointing leaks doesn't just help scientists get a better picture of emissions, it also helps landfill operators fix leaks. Keeping more waste out of the landfill, for example by composting food scraps, is another fix. 'The Environmental Protection Agency estimates that landfills are the third largest source of human-caused methane emissions in the United States, emitting as much greenhouse gas as 23 million gasoline cars driven for a year,' notes the NYT. 'Overseas, the picture can be less clear, particularly in countries where landfills aren't strictly regulated. Previous surveys using satellite technology have estimated that globally, landfill methane makes up nearly 20 percent of human-linked methane emissions.'

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