Warnings of gas pipelines pepper the Santa Susana Mountain range miles Southern California Gas Company's fenced-off Aliso Canyon facility. 14 Dec, 2015 © Scott Liebenson

In a sunny suburb of Los Angeles, California, an invisible menace rages.

A massive natural gas leak is venting 50 tons of natural gas per hour into the atmosphere, making it the largest gas leak ever recorded.

First detected on 23 October, the leak emanates from a gas storage well owned by Southern California Gas (a subsidiary of Sempra Energy) in Aliso Canyon, located in the San Fernando Valley region of Southern California. The company claims the leak will be plugged in late February at the earliest.

While the leak itself cannot be seen (natural gas is invisible to the naked eye), the effects can; bleeding gums and noses, headaches and empty schools.

Special equipment makes the extent of the gas leak visible. Photo Credit: EDF

The disaster has forced thousands of residents of the Porter Ranch neighborhood in Los Angeles away from their homes and forced California Governor Jerry Brown to declare a state of emergency.

The leak is mostly methane gas, the primary component of natural gas. Methane is an explosive greenhouse gas that can displace oxygen and cause asphyxiation. While methane itself is non-toxic, the potent cancer-causing toxin benzene and noxious chemical hydrogen sulfide have also been detected in the Porter Ranch area. A chemical called mercaptan — added to make gas leaks detectable by smell — has made the area reek of rotten eggs.

What it means for the climate

Locals suffering the immediate effects of this disaster are not the only casualties. Make no mistake, this leak has a major impact on our global climate.

Methane is 84 times as powerful than carbon dioxide at disrupting the climate over a 20-year period. This leak is already the biggest single source of climate pollution in the state of California, equal to the exhaust of 7 million cars every day.

This disaster highlights the dangers of relying on fossil fuels like natural gas. While the fossil fuel industry portrays gas as an environmentally responsible alternative, this leak is a stark reminder that it’s time to keep climate pollutants like methane in the ground and switch to safe energy sources like wind and solar.

Until we do, these are the consequences of our choices:

Jesse Coleman is a researcher with the Investigations Team at Greenpeace USA.

This blog was originally posted by Greenpeace USA.