Aerial view of the leaking Aliso Canyon well that polluted the Porter Ranch community in Los Angeles County. Photo was taken on December 17, 2015. Earthworks/Flickr Remember that gas leak that sprang from a natural gas well in the Southern California town of Porter Ranch last fall?

Scientists just confirmed that it was the largest methane gas leak the US has ever endured, according to a study published February 25 in the journal Science.

Scientists have even calculated that the amount of methane that leaked each day was enough to fill a balloon the size of the Rose Bowl.

The leak, which sprang on October 23, 2015 from a natural gas well in a quiet, hilly town in northern Los Angeles, uncontrollably spewed more than 100,000 tons of methane — a potent greenhouse gas — into the sky before it was finally plugged four months later on February 18, 2016, scientists announced.

To put the environmental impact into perspective, the amount of methane released from the well is equivalent to the annual emissions of nearly 500,000 passenger vehicles.

Shortly after the leak, residents said they became sickened from the noxious fumes, experiencing nausea, nosebleeds, and headaches. Thousands were displaced, and community members and activists pointed fingers at SoCalGas, the owner of the well, for not taking proper precautions. At least dozens of lawsuits are currently pending.

In addition to this being the worst methane leak in the history of the US, activists and officials have deemed this one of the most deplorable environmental catastrophes in recent years, drawing comparisons to some of the most egregious man-made mishaps.

Environmental activist Erin Brockovich labeled this one of the worst environmental disasters since the 2010 BP oil spill in the Gulf of Mexico, which for nearly three months leaked more than 3 million barrels of oil into the gulf. Even today, nearly five years later, oil still dots beaches along the Louisiana coast with tar, choking mangrove trees and sickening dolphins.

In a public hearing on January 9, L.A. County Supervisor Michael D. Antonovich referred to the leak as a "mini Chernobyl," according to the Los Angeles Times.

That's right, Antonovich compared the leak to the 1986 nuclear power plant disaster in Ukraine, which spewed radioactive material into the sky — killing two plant workers during the release and 28 people in the next few weeks due to acute radiation poisoning. It's considered one of the "most serious accidents in nuclear history."

Porter Ranch resident holds a protest sign outside Los Angeles City Hall during a demonstration ahead of the testimony before the Los Angeles City Council on the ongoing natural gas leak in the Porter Ranch area of Los Angeles, California on December 1, 2015 Gus Ruelas/Reuters According to the Centers for Disease Control and Prevention, exposure to the chemical mercaptan, which is added to the gas to give it that quintessential (and detectable) sulfurous smell, can cause staggered gait, vomiting, irritation of the respiratory system, wheezing, rapid heart beat, arm and leg rigidity, bluish discoloration of the skin, and irritated eyes and mucous membranes.

Industrial exposures could even put someone in a coma and cause death by a blocked lung artery up to 28 days later.

While the human side effects from the gas are temporary, the atmospheric damage from the leak is lasting.

Much like a blanket, greenhouse gases advance global warming by trapping heat in the atmosphere. While methane is the second most abundant greenhouse gas after carbon dioxide, it is arguably worse for the environment. It doesn't stick around in the atmosphere as long as carbon dioxide, but it locks heat into our atmosphere more efficiently.

Experts estimate that methane can warm the planet tens, hundreds, or even thousands of times better than carbon dioxide can.

Methane, mercaptan, and other gases that poured from the well are invisible to the naked eye. But an infrared camera, operated by an Earthworks ITC-certified thermographer, was able to reveal the enormous methane plume in action on December 17:

SoCalGas crews finally drilled a relief well that they pumped with fluids and cement to intercept and plug the flow of gas from the leaking well. But while the leak has stopped, the effects will severely hamper California's greenhous gas emissions targets for the year, scientists said in a press release.

“Our results show how failures of natural gas infrastructure can significantly impact greenhouse gas control efforts,” Tom Ryerson, a chemist with the National Oceanic and Atmospheric Administration and co-lead scientist on the study released today, said in a press release.

The event was so huge, the team studying the plume even had to check their gas-sniffing gear to ensure it was working properly.

"It became obvious that there wasn’t anything wrong with the instruments," co-author Stephen Conley of Scientific Aviation and UC Davis said in the release. "This was just a huge event."