California methane leak was biggest in US

The monthslong natural gas leak that forced thousands of Los Angeles residents from their homes ranks as the largest known accidental methane release in US history, equal to the annual greenhouse gas emissions of nearly 600,000 cars, scientists reported on Thursday.

At its peak, 60 tons per hour of natural gas was spewing from a ruptured underground pipeline at the Aliso Canyon storage field, effectively doubling the methane emissions of the entire Los Angeles metropolitan area, the researchers said.

Their study, published in the journal Science, represents the first comprehensive effort to quantify a gas leak that made scores of people ill and prompted the temporary relocation of more than 6,600 households from the northern Los Angeles community of Porter Ranch at the edge of the gas field.