Michael Mann, one of the nation’s most prominent climate scientists, told a Washington, D.C. jury on Wednesday that he was made to feel like a “pariah” and saw his grant funding plummet after right-wing bloggers sought to discredit his science with vulgar attacks in 2012.

Mann sued the bloggers for defamation after they drew comparisons between his science and a child sex abuse scandal that had rocked his institution, Pennsylvania State University, that year. They wrote that he had “molested and tortured data,” and that the school had engaged in a “whitewash” of his science, much as it had failed to unearth the transgressions of Penn State’s disgraced assistant football coach, Jerry Sandusky.

“They crossed a line,” Mann told the jury from the witness stand. “They compared me to a convicted child molester and made false allegations of scientific misconduct against me.”

Noting that at the time he was the father of a daughter who was not much younger than Sandusky’s victims, Mann said, “For me to be compared to Jerry Sandusky was maybe the worst thing that I had ever experienced.”

It has been a dozen-year journey to the courtroom for Mann, author of some of the most influential science on climate change, including the so-called “Hockey Stick” graph charting this century’s dramatic temperature rise. Mann had been a target of climate science deniers for years before the 2012 posts. His emails and those of other climate scientists were hacked and dumped on the Internet in the runup to international climate talks at Copenhagen in 2009, a crime that has never been solved. Although climate action foes sought to characterize those emails as containing evidence of manipulation by the climate scientists, 11 investigations by scientific organizations and institutions in the United States and the United Kingdom—including Penn State—found no evidence of wrongdoing.

But the investigations did nothing to sway hard-core climate change denialists. And in 2012, the Sandusky scandal at Penn State offered a salacious new metaphor for Mann’s attackers.

The bloggers and their supporters argued that their criticisms of Mann were protected by the First Amendment, but the U.S. Supreme Court in 2019 rejected their bid to block the suit on those grounds. The case was eventually pared down, with a court ruling in 2021 that the blog publishers, the right-wing think tank the Competitive Enterprise Institute (CEI) and National Review magazine, could not be held liable for the writings of their part-time contributors.

The only remaining defendants are the two bloggers, Rand Simberg, a former aerospace engineer and adjunct scholar for CEI, and Mark Steyn, a conservative author and TV host. Mann, as a public figure, has a high burden of proof to make his defamation case in D.C.; he must show the defendants acted with knowing falsehood or reckless disregard for the truth.

Steyn, on the witness stand this week, described only cursory research into the U.S. investigations of Mann as he defended the veracity of his column, “The Other Scandal in Unhappy Valley.”

“As I’ve told you, I did not appraise myself of the details of your American investigations before I wrote my entirely truthful piece,” Steyn replied to questioning from Mann’s lawyer, John Williams.

Steyn repeatedly portrayed U.S. scientific agencies as an obtuse collection of bodies that “begin with the letter ‘N,’” which he, as a Canadian citizen, found difficult to comprehend. “I’m a subject of his Canadian majesty,” he said. At one point, Steyn, who was educated in London, referred to D.C. Superior Court Judge Alfred Irving as “m’lord.”

A guest host for Tucker Carlson and Rush Limbaugh over the years, he had his own show for a time on the British news channel GB News, but that stint ended in both personal and professional setbacks. He suffered the first of three heart attacks while on air in December 2022, and soon afterward was accused by the British media regulator of presenting misleading information on vaccines to viewers. 

But Steyn has not lost his passion for blogging. He and his colleagues are posting daily reports on the Mann trial on his web site, Steynonline.com, where he is selling a trial souvenir. The limited edition “Liberty Stick,” a signed hockey stick etched with passages of the U.S. Constitution, costs $100.

Mann, who now directs a Center for Science, Sustainability and the Media at the University of Pennsylvania, needs to show that he was harmed by the 2012 blog posts in order to recover damages. Mann’s original complaint says he is seeking both compensatory and punitive damages “in an amount to be proven at trial.” 

Before the jury, he detailed what he said was a marked decline in interest in his work from funders after the blog posts’ publication. In the four years prior to the blogs, he said he won $3.3 million in grants, with nine out of his 15 grant applications being successful. In the four following years, he won only two of seven grants he applied for, with support falling to $500,000, Mann testified.

He also talked of harsh stares when he went to the supermarket in central Pennsylvania with his family, in a community that was deeply shaken by the revelations about Penn State’s cherished football program. “To be connected to it in that way really impacted the way I was perceived … I felt like a pariah in my own community,” he testified.

But it was not immediately clear how much of Mann’s testimony of the personal impact of the attacks the jury could consider. Irving, appointed to the D.C. bench by President George W. Bush, repeatedly sustained objections from Simburg’s lawyer, Victoria Weatherford of the prominent corporate law firm BakerHostetler. BakerHostetler, as longtime counsel to CEI, years ago made  the argument that disagreement with accepted climate science was a First Amendment right, when the think tank became enmeshed in the state investigations of the oil giant Exxon’s history of climate denial.

Mann did have a chance to delve into the history of the hockey stick paper. “It told a pretty simple story,” Mann said. “The data led us to the inescapable conclusion that there really was something unusual happening in the modern era, that the warming that we saw exceeded what we see in the past, even taking into account the fairly substantial uncertainties.”

After testimony from both Mann and Steyn, Irving urged the jury to keep an open mind, since numerous experts would be testifying in a trial expected to last into February.