article: Jerry Brown ordered "all necessary and viable actions" be taken to stop it. More than 2,000 families have been moved from their homes and many people have reported feeling ill because of the leakage, which began in October. It stems from a vast underground storage field in Porter Ranch, on the outskirts of Los Angeles. Gas is spewing into the atmosphere at a rate so fast that the well now accounts for about a quarter of the state's total emissions of methane - an extremely potent greenhouse gas. The well is situated in a mountainous area more than a mile away from residential areas, but residents have complained of health effects like headaches, nausea, vomiting and trouble breathing. "Let's call it an environmental and public health catastrophe," Tim O'Connor, a lawyer with the Environmental Defense Fund, told the BBC's environment correspondent, Matt McGrath. "In terms of timelines this is going to surpass the gulf oil problem by a mile. What we do know is that that climate equivalent of this leak is like burning thus far almost 700 million gallons of gasoline or it's the same amount of pollution as 4.5 million cars put out every day, it's tragic." Methane - the main component of natural gas - is a very strong greenhouse gas, capable of trapping solar radiation in the atmosphere. It belongs to a category of gases called short-lived climate pollutants. While methane and other short-lived pollutants remain in the atmosphere for a relatively short time compared to other gases, the California Air Resources Board says that "when measured in terms of how they heat the atmosphere, their impacts can be tens, hundreds, or even thousands of times greater than that of carbon dioxide". The BBC's Matt McGrath says the large amounts of powerful gas that are leaking could have a significant impact on climate change. Residents have been complaining of nausea, headaches and other symptoms, but the utility company says that "scientists agree natural gas is not toxic and that its odorant is harmless at the minute levels at which it is added to natural gas". Health officials in the area have said the long-term effects of being exposed to the gas are unknown. The utility company is providing temporary accommodation or funds for the displaced residents, and several thousand people in Porter Ranch have been relocated while the gas continues to leak and repairs take place. But, according to CBS News, only 2,200 families have been relocated even though 6,500 have applied for help. "You have kids going to school outside their neighbourhoods, families that are living in hotels" says Paula Cracium, president of the Porter Ranch Neighborhood Council. "The longer this goes on the more stress there is." A broken injection-well pipe about 500 ft (152.4m) below the surface is believed to be the culprit behind the leak, reports say. Pipes like this are used by utility companies to insert gas into the ground for storage until a later time when it can be withdrawn and sold for use. It is not known why the pipe ruptured.
summary: The governor of California has declared a state of emergency in a suburb of Los Angeles over the leaking of methane gas from an underground storage field.