Despite public warnings about the dangers of climate change, Facebook, Google, and Microsoft all supported a conference that promoted climate change denialism, according to a new report from Mother Jones.

The three companies were all sponsors of LibertyCon, a convention aimed at a libertarian audience that took place this month. The convention included a speaker from a group called the CO2 Coalition, who reportedly argued that the impact of climate change on the environment has been exaggerated.

The three companies were LibertyCon sponsors

In a schedule for the conference, the talk — titled “Let’s Talk About Not Talking: Should there be ‘No Debate’ that Industrial Carbon Dioxide is Causing Climate Catastrophe?” —promised to “explain the workings of the mathematical models that are used to predict the future of climate change and are the basis for media fears of impending disaster.”

Mother Jones reports that the speaker claimed that the effects of climate change on severe weather had been exaggerated and that “the data don’t show a worrisome trend,” a suggestion that’s at odds with the expert consensus on climate change.

Tech companies frequently sponsor events across a range of political views. Facebook and Google have famously supported the conservative CPAC conference — even during a time when many conservatives have been critical of the companies. While those conferences often host several different speakers, controversy over the LibertyCon talk shows how sponsoring an event can lead companies to be linked to speakers who don’t share their professed views. (All three companies have pledged to battle climate change.)

In a statement, a Facebook spokesperson pointed to a page on the company’s political activities. “Sometimes we support events that highlight Internet and social media issues,” the page reads, listing a range of events the company supports.

“Our commitment to sustainability is not altered or affected by our membership or sponsorship of an organization,” a Microsoft spokesperson said in a statement. “We work with many groups on technology policy issues and do not expect or anticipate that any organization’s agenda will align to ours in all policy areas.”

“Every year, we sponsor organizations from across the political spectrum to promote strong technology laws,” a Google spokesperson said in a statement. “As we make clear in our public policy transparency report, Google’s sponsorship or collaboration with a third party organization doesn’t mean that we endorse the organization’s entire agenda or agree with other speakers or sponsors.”

Update, 2:02 PM ET: Includes statement from Microsoft spokesperson.