YouTube has been recommending and serving ads against videos that feature denial of or misinformation about climate change, according to a new report. The identified videos had 21.1 million views between them and might be suggested to users after a search for “climate change,” “global warming,” or the conspiracy theory “climate manipulation.”

The study, from the nonprofit activist group Avaaz, found ads from 108 brands running on videos that contained climate change misinformation. Those brands included major companies like Samsung, Uber, Nintendo, Showtime, Harley Davidson, and Warner Bros. Ads for environmental groups, including Greenpeace and the World Wildlife Fund, appeared on the videos as well. Avaaz says 10 advertisers, including Samsung and the environmental groups, said they were unaware their ads appeared on these videos (the others didn’t respond).

Avaaz wants advertisers to pressure YouTube to stop promoting and putting ads on misinformation

The report also states that YouTube promotes these videos in its “up next” box, but the evidence is less clear-cut. In a statement emailed to The Verge, YouTube called into question the methodology of the report, which used an indirect method for assessing video recommendations, and said that its platform prioritizes “authoritative voices” on topics prone to misinformation, like climate change.

YouTube has long struggled to find a balance between maintaining an open platform and keeping its platform safe for both viewers and advertisers. In the past, companies have paused ad spending after learning that their commercials ran on videos that featured hate speech or comment sections with predatory remarks about children. This has led to YouTube placing stricter rules on creators, limiting what videos they can make money on, and changing its video promotion algorithms, such as to limit the spread of conspiracy theories.

Avaaz’s study shows just how fraught finding that balance can be. Three of the top climate change denial videos it highlights come from Fox News and PragerU (which is not a university, but a nonprofit making videos that “function as dog whistles to the extreme right,” according to the Southern Poverty Law Center). Several videos cast doubt on whether greenhouse gas emissions are leading to higher global temperatures — a widely accepted conclusion among climate researchers and the broader scientific community.

“If there is factually inaccurate information in the video, then YouTube should not be giving it free advertising.”

While known to be wrong, these are not just views espoused by fringe YouTubers — they’re promoted by major political figures and, in some instances, the president of the United States. As a result, putting restrictions on these videos would mean wading into a political battle that YouTube would rather avoid, despite climate change being an existential threat that urgently needs to be addressed.

By highlighting the major advertisers that become aligned with these extremist viewpoints because of YouTube, Avaaz hopes to build the necessary pressure on YouTube to make a change. (Samsung says it immediately contacted YouTube to “resolve the current issue and prevent future repetition.”) Avaaz’s goal with this latest report is not to ban climate change denial videos, but to get YouTube to stop running ads on them and recommending them to viewers.

“This isn’t about removing content, this isn’t about sanctioning different channels or media outlets,” says Nell Greenberg, a campaign director at Avaaz who oversaw the report. “This is simply saying if there is factually inaccurate information in the video, then YouTube should not be giving it free advertising.”

Advertisers currently have the option to prevent their ads from running on any videos that discuss climate change. But they don’t have an option to only run on accurate videos about climate change — it’s all or nothing. “A lot of brands want their ads on climate change videos. They’re environmental organizations or do a lot for sustainability,” Greenberg says. “They don’t want ads running on videos that have factually inaccurate information, and that’s not available to them.”

The study didn’t look directly at YouTube recommendations, so it’s not clear which videos are actually being promoted

Avaaz was able to directly confirm that ads were running on videos that featured climate change misinformation by watching the videos. However, its evidence that YouTube promotes these videos through its “up next” feature is shakier, because it didn’t directly observe the feature in action.

Instead, Avaaz relied on a YouTube developer tool that presents what videos might be related to others. The resulting list “does not provide an exact replica of YouTube’s suggestions algorithm,” the study says. YouTube says the tool may be biased by, for example, a website that embeds multiple videos side by side. Avaaz believes the data “very likely” represents much of what YouTube’s suggestions would present to viewers, but it didn’t confirm that any of these videos actually show up.

Avaaz’s study looked at what it deems likely to be the first 100 “up next” recommendations for videos related to each of the three search terms. It then had people watch through those videos to look for misinformation — a term it took to broadly mean any “verifiably false or misleading” statements. “Global warming” led to 16 videos with misinformation; “climate change” to eight; and “climate manipulation” to 21.

YouTube has taken steps to fight misinformation. Some search results and videos now include a fact-check box with information pulled from Wikipedia. Searching “climate change” and “global warming” will present you with this box, however “climate manipulation” does not. It’s also reduced recommendations of “borderline content” — videos it deems as problematic, but not quite troubling enough to be banned — such as medical misinformation and conspiracy theories.

“As our systems appear to have done in the majority of cases in this report, we prioritize authoritative voices for millions of news and information queries, and surface information panels on topics prone to misinformation — including climate change — to provide users with context alongside their content,” a YouTube spokesperson said in a statement.

YouTube doesn’t outright ban climate change denial. However, because it views climate change as a subject prone to misinformation, authoritative sources are supposed to be prioritized in search and recommendations. That means news reports on climate change should show up before videos from individual YouTube creators, but it also means that a major cable channel that broadly denies the existence of climate change would be considered authoritative, too, even if it’s spreading misinformation.

“For very good reason, there is conversation that gets wrapped up in this about free speech,” Greenberg says. “We are not in any way talking about free speech — what we’re talking about is free advertising and free promotion, and that’s what the YouTube recommendation algorithms are doing.”