The natural gas leak in the Porter Ranch neighborhood of L.A. County is turning into a major disaster. Thousands of residents have been moved out of their homes. Schools have been relocated. People have suffered headaches, nausea, nosebleeds, and other symptoms. The leak was detected back in October. But it has taken until this week for Gov. Jerry Brown to get involved and declare a state of emergency. Meanwhile, cleanup could cost billions. And the leak is so bad, it’s impacting global warming emissions targets for the whole state. We get the ground-level and big-picture views.