Climate deniers looking to block action and "greenwashing" companies could have free rein on Twitter after Elon Musk's takeover, analysts warned as leaders pursued anti-warming efforts at the COP27 summit.

The Tesla billionaire and self-declared free-speech absolutist have fired thousands of staff — with sustainability executives Sean Boyle and Casey Junod among those signing off from the platform last week.

Musk has promised to reduce Twitter's content restrictions and after the takeover announced plans to create a "content moderation council" to review policies.

"It's not clear what Mr. Musk really plans to do. However… if he removes all attempts at content moderation, we can expect a surge of disinformation, as well as increases in misleading and greenwashing advertisements," said Naomi Oreskes, a professor of the history of science at Harvard University who has authored leading studies on climate misinformation.

"Greenwashing" means companies misleading the public about their impact on the planet through messages and token gestures.

"We may also see an increase in hateful comments directed towards climate scientists and advocates, particularly women," Oreskes said.

Following the buyout, one climate journalist tweeted that he had received death threats on the platform. He did not immediately respond to a request for comment.

Sustainability execs axed

Researchers and campaigners say that despite measures announced by social platforms, climate misinformation is thriving, undermining belief in climate change and the action needed to tackle it.

Twitter and other tech giants such as Facebook and Google have said they are acting to make false claims less visible.

But the Institute for Strategic Dialogue think tank said in a detailed study this year that messages aiming to "deny, deceive and delay" regarding climate action were prevalent across social media.

Under Twitter's policy before the takeover, it said "misleading advertisements on Twitter that contradict the scientific consensus on climate change are prohibited".