Climate denialists have been plotting a full-scale attack against author and science historian Naomi Oreskes, ahead of the release this Friday of a feature film based on the book she co-authored in 2010, Merchants of Doubt.

“This is part of their intimidation,” Oreskes said. “It’s a part about trying to make people frightened that if they do speak up and they do expose what’s going on, they’ll get attacked. And they will get attacked. I’ve been attacked.”

In a series of emails obtained by Climate Wire, physicist Fred Singer—one of a handful of veteran denialists profiled in the book—“ sought the advice of nearly 30 climate skeptics about their chances of halting the movie,” Lehmann writes. James Enstrom, an epidemiologist who previously challenged science on the health risks of second-hand smoke and particulate air pollution, suggested complaining to the universities with which Oreskes is affiliated.

“I suggest you Attack Oreskes by Filing short Grievances with Harvard and Stanford,” Enstrom wrote to Singer on Oct. 21. “Good thought,” Singer responded.

Singer has sent mixed messages about whether he will pursue litigation against the film. “I would prefer to avoid having to go to court; but if we do, we are confident that we will prevail,” he wrote in a letter to director Robert Kenner. “I think there’s a pattern,” Kenner told Climate Wire. “It’s to come after and try to silence critics and to intimidate. And when [Singer] implies litigation is very expensive, I think it’s an attempt to be intimidating.”