Yale Environment 360: 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 hourthe equivalent of the annual greenhouse gas emissions of 572,000 cars. Methane is a greenhouse gas dramatically more potent than carbon dioxide...