A two-minute video attacking the scientific consensus on climate change — made by infamous denier Marc Morano — is going viral. While the Guardian has already thoroughly debunked the content of the video, it’s still making the rounds on social media. On Tuesday, it had racked up over 100,000 shares and 6.3 million views on Facebook.

Even though the social media site has bragged about hiring third-party fact-checkers in many countries to cope with its fake-news problem, its approach to fake science remains obscure. “I don’t know if they are even fact-checking science,” says Gordon Pennycook, a professor at Canada’s University of Regina who studies fake news and political bias.

John Cook, who focuses on climate misinformation as a professor of cognitive science at George Mason University, says he hasn’t heard of the social media giant flagging any climate denial content. “Facebook’s fact-checking algorithms are a bit of a black box,” he tells Grist via email. (The social media site did not respond to a request for comment.)

Instead, Facebook seems to be taking aim at lower-hanging fruit, by limiting the spread of sensational stories from websites known to peddle in falsehoods like Infowars and YourNewsWire. “There’s a wide world of B.S., unfortunately,” Pennycook says.

But while fact-checkers focus on falsehoods akin to “Pizzagate,” fake science stories — which have the potential to influence public policy, health, and the future of the earth — can spread widely. Anti-vaccine groups run rampant on Facebook, with hundreds of thousands of followers exposed to misinformation about health risks of immunization. And the Flat Earth Society (don’t get me started), has more than 150,000 followers, although some of them (hopefully) follow the page as a joke.

Facebook can point to one example of it fact-checking science: Earlier this year, the social-media platform blogged that it had stopped the spread of a viral story about ending strokes by pricking a finger with a needle. But it’s hard to square this tiny victory with the other science misinformation circulating every day on the platform.

In 2016, an investigation by DeSmog found that the most-shared climate article throughout the year was a hoax piece that — like Morano’s video — critiqued the 97-percent scientific consensus on anthropogenic climate change. This is bad news, especially considering that psychologists have found that attacking consensus is one of the best ways to sow doubt.

Worse, some of Facebook’s third-party fact-checkers are known climate deniers themselves. The Weekly Standard, which was announced as a fact-checking partner in December, has called climate science “Dadaist science” and has critiqued climate action. The fossil fuel-funded Heritage Foundation has espoused climate change denial for decades — and is now partnered with Facebook to investigate possible “liberal bias” in its operations. As Joe Romm writes for ThinkProgress: “This is indeed the fox guarding the henhouse.”

But even if Facebook initiated substantial science fact-checking, it might not be able to stem the flow of denial. Researchers last year found that being “debunked” simply caused many conspiracy theorists to double down on their claims. And since these misinformers inhabit online echo chambers, they rarely see pieces getting debunked anyway.

Still, Cook thinks that Facebook should work on fact-checking science content on its platform. “They can’t just say they’re engineers and they’re absolved of responsibility,” he tells Grist. But he also has another, novel idea for preventing the spread of misinformation: a technique called “inoculation.”

While we might not be able to change the minds of current deniers, Cook explains, we can prevent others from being taken in by their claims. By giving individuals a sample of misinformation — and then explaining the psychology behind it — he believes communicators can “neutralize misinformation” before it starts to spread. “If you explain the techniques used to mislead people, they’re no longer influenced by them,” he says.

It’s ironic that the idea of inoculation, which anti-vaxxers have disparaged for years, could serve as a way to fight the very misinformation that they spread. But any large-scale effort to guard against climate denial or other false science will take a long time, and a lot of education. Like it or not, we need climate action now — and Facebook is still part of the problem.