Good news: The end of California’s massive, damaging Porter Ranch gas leak is finally in sight

The worst environmental disaster in the US since the BP oil spill might finally be ending.

Since October, a gas well near the Porter Ranch neighborhood in northern Los Angeles has been leaking, spewing methane, a greenhouse gas, into the air. So far, it's emitted more than 96,000 metric tons of methane, the equivalent of putting half a million more passenger vehicles on the road for a year.

The Southern California Gas Company announced Thursday it had plugged the leak temporarily, the first step toward a permanent fix:

We've temporarily controlled flow of gas & initiated process of stopping leak: https://t.co/CO4z3gb99Y #PorterRanch pic.twitter.com/WJ3MORPW81

— SoCalGas (@socalgas) February 11, 2016

That means residents of Porter Ranch might get some relief from nausea, headaches, and other symptoms caused by chemicals added to natural gas to give it its distinctive smell.

But the environmental damage will linger much longer. Methane is a powerful contributor to climate change — 34 times more potent than carbon dioxide over a 100-year period — and methane emissions have caused about 25 percent of today's climate change, according to the Environmental Defense Fund.

California Gov. Jerry Brown has declared a state of emergency, and the gas company faces criminal charges due to its delay in notifying state authorities about the leak as well as a civil suit from the state attorney general.

Go deeper:

• The Los Angeles Times is the essential source for Porter Ranch coverage, including local residents' symptoms, how much damage the leak might do, and why the leak took so long to fix.
• Most methane leaks aren't as dramatic as the gusher at Porter Ranch. But a study from the Environmental Defense Fund found they're widespread, particularly in cities with aging infrastructure.
• The White House has a goal to reduce methane emissions, which experts argue is crucial to meeting overall emissions reduction goals.