 100,000 tons of methane. That's how much methane was released following the massive blowout of a well connected to the fourth largest U.S. natural gas storage facility last October in Aliso Canyon, California. The well was finally plugged on February 18, 2016, but by then, the damage was already done. The Aliso Canyon gas leak was the largest methane leak in U.S. history, according to the first study of the blowout. That means that it dumped more methane into the atmosphere than the Deepwater Horizon oil spill or the collapse of the Yaghi Natural Gas Storage Facility in 2001. Methane is an incredibly dangerous greenhouse gas. Although it doesn't linger as long in the atmosphere as carbon dioxide, it's far more potent because it can absorb heat very effectively and trap it in the atmosphere. And more heat trapped in the atmosphere means higher average temperatures around the world, which can have many consequences, melting ice caps, rising oceans, extreme weather, and ecosystem loss, to name a few. That's why it was important for researchers to determine exactly how much methane was released from the Aliso Canyon leak to begin to estimate how much damage was done. To do that, the researchers used surface air sampling devices and a specially equipped plane that flew over the area of the leak 13 times between November 7, 2015 and February 13, 2016, two days after the leak was temporarily sealed. They found that at its peak, the Aliso Canyon gas leak doubled the rate of methane emissions from the entire Los Angeles basin, and temporarily created the largest known human-caused point source of methane in the U.S., doubling the next largest source in Alabama coal mine. That means that the Aliso Canyon leak's impact on the global climate is equivalent to the annual greenhouse gas emissions of over half a million passenger cars. What Aliso Canyon released is about 0.0002 percent of the world's methane. But if you look at it on the scale of any other leaks around the world, it's a monster. Leaks like Aliso, the more of those we have, as you add them up, they begin to make a huge contribution to global climate change. The gas leak didn't just release methane, however. Samples taken near homes in the nearby town of Porter Ranch contained above-normal levels of potentially dangerous compounds present in natural gas, including benzene, toluene and silenes. Benzene especially is a known carcinogen not recommended at levels higher than one part per million. Methane leaks aren't uncommon at natural gas facilities, but what's especially worrisome here is how long it took to fix the leak. SoCal Gas attempted to seal a leak seven times over a 112-day period before it finally succeeded. California Governor Jerry Brown declared a state of emergency on January 7, nearly two months after the leak began. Thousands of people relocated from the area after complaints of nausea and other illnesses connected with methane exposure became widespread. The disaster has drawn attention to the broader issues associated with natural gas production — rogue emissions, crumbling infrastructure and lax regulations. Instead of relying on information released from companies like SoCal Gas, the company that owns the ruptured well, independent researchers could provide fast and accurate information to regulators and the general public during major chemical releases. Having reliable and continuous measurements of natural gas in other facilities could prevent major incidents like the Aliso Canyon blowout from happening again.