The four-month natural gas leak that sickened hundreds of Los Angeles residents and forced the evacuations of 1,800 homes this winter has officially been deemed the largest methane leak in U.S. history, according to a study in the journal Science.
The California leak spewed a total 97,100 metric tons of methane into the atmosphere, up to 60 tons per hour—the equivalent of the annual greenhouse gas emissions of 572,000 cars. Methane is a greenhouse gas dramatically more potent than carbon dioxide over a short time span. The researchers collected the data during 13 different flights through the leaking gas plume. The measurements were so high the scientists said they double-checked their recording devices. “It became obvious that there wasn’t anything wrong with the instruments,” said Stephen Conley, an atmospheric scientists at the University of California-Davis who led the study. “This was just a huge event.”