California methane gas leak 'largest' in US history: Scientists

The methane leak, detected at the gas company`s Aliso Canyon facility, has been described as an environmental disaster.

Los Angeles: The massive methane gas leak that sickened Los Angeles residents and forced thousands from their homes was the 'largest' in the US history, says a study.

Scientists believe the months-long blowout from a well at a Southern California Gas company storage facility, spewed almost 100,000 tons of the powerful greenhouse gas methane. That would be equivalent to the annual emissions of half a million cars.

The leak, first detected on October 23 at the gas company`s Aliso Canyon facility, has been described as an environmental disaster.

According to scientists, the leak had a far bigger warming effect than the BP oil spill in the Gulf of Mexico in 2010.

After several unsuccessful attempts, the leak was permanently sealed on 18 February. But, by then almost 100,000 tonnes of methane had been released into the atmosphere.

To assess the impact of the leak, researchers examined air samples collected in and around the methane plume as well as from the ground via 13 flights aboard a small aircraft over three months of the leak.

They found that the amount of methane released into the atmosphere from the leak was the largest of its kind recorded in the uS history.

A bigger accident occured in Texas in 2004, but most of the methane gas was consumed in an explosion and fire, so that methane never reached the atmosphere, the study said.

"In terms of the methane release, Aliso Canyon is by far largest," said lead author Dr Stephen Conley, from the University of California, Davis.

"It had the largest climate impact; it beats the BP oil spill."

The blowout will also hobble California's effor to meet its greenhouse gas emissions targets this year, said researchers.

Methane is a more potent greenhouse gas than carbon dioxide, persists in the atmosphere for 10 years. The comparative impact of methane on climate change is more than 25 times greater than carbon dioxide over a 100-year period.

The study has been published in the journal Science.