Follow Us

Celebrity renewable energy researcher loses appeal, but questions about free speech remain

Jacobson’s case involved an article published in a scientific journal, which may have afforded it some protections, based on the court’s ruling, but questions remain about free speech protections for those publishing outside scientific journals.

Published: March 1, 2024 11:00pm

Celebrity Stanford professor Mark Z. Jacobson, who filed a failed $10 million defamation suit against a scientific journal and the lead author of a study that criticized his research, lost his appeal to avoid paying $500,000 in legal fees to the defendants.

The case has been compared to Penn State climate scientist Michael Mann’s defamation suit, which played out in the same court. The jury in Mann’s case awarded him over $1 million.

Jacobson’s case involved an article published in a scientific journal, which may have afforded it some protections, based on the court’s ruling, but questions remain about free speech protections for those publishing outside scientific journals.

Numerous shortcomings

Mark Z. Jacobson in 2015 published a study in The Proceedings of the National Academy of Sciences (PNAS) that concluded it was technically and economically possible to power the United States entirely with wind, solar and hydroelectric, backed up with energy storage systems.

The study made Jacobson an instant renewable energy celebrity. He appeared on David Letterman in 2013, rubbed elbows with Sen. Bernie Sanders, and actor Leonardo DiCaprio cited Jacobson’s research in a speech at a United Nations climate summit.

Two years later, Christopher Clack, formerly with the University of Colorado Boulder and Vibrant Clean Energy, along with 20 other researchers, published a paper in PNAS that found “numerous shortcomings and errors” in Jacobson’s study. According to Clack and his colleagues, Jacobson used “invalid modeling tools, contained modeling errors and made implausible and inadequately supported assumptions.”

These errors “render it [the study] unreliable as a guide about the likely cost, technical reliability, or feasibility of a 100% wind, solar, and hydroelectric power system,” the authors wrote.

Jacobson responded by suing Clack and PNAS for defamation, seeking $10 million in damages. Jacobson warned PNAS not to publish Clack’s article, The College Fix reported in 2017, arguing that it contained 30 “false statements” and five “materially misleading” statements. Jacobson, according to the suit, requested that the statements be corrected. Most of the items on Jacobson’s list were left in Clack’s published study.

PNAS asked the District of Columbia court to dismiss Jacobson’s suit, claiming that the researcher had filed the suit to “silence those who disagree with him.”

Jacobson voluntarily dropped the suit in 2018. He issued a statement on his decision, saying he filed the lawsuit not because the defendants disagreed with his scientific findings. Rather, Jacobson claimed, they had “knowingly and/or recklessly published false statements of fact.” He told Retraction Watch that he had been expecting the defendants to settle, and he grew concerned about the costs of a lengthy trial process.

The defendants filed an anti-SLAPP suit against Jacobson. Anti-SLAPP laws provide a means for defendants in libel lawsuits to have cases dismissed at an early stage. In some cases under some state laws, the plaintiffs in libel suits who lose anti-SLAPP suits can be made to repay legal expenses of the defendants.

In April 2020, District of Columbia Superior Court Judge Elizabeth Carroll Wingo, Retraction Watch reported, ruled that Jacobson would have to pay back the defendants’ legal costs. Wingo stated in her decision that the “egregious errors” Jacobson said were published by PNAS reflected “scientific disagreements, which were appropriately explored and challenged in scientific publications; they simply do not attack Dr. Jacobson’s honesty or accuse him of misconduct.”

Jacobson appealed the decision, arguing that by dropping his defamation suit, he wasn’t liable according to statutes.

But the District of Columbia Court of Appeals disagreed. In a ruling Thursday, Justice Joshua Deahl wrote, that “a plaintiff could engage in harassing and meritless litigation up until the point at which they sense the court might dismiss the case, and then voluntarily dismiss the suit themselves, all the while keeping the threat of refiling hanging over the defendants’ heads and running up their legal bills.”

In a statement issued to Retraction Watch, Jacobson said he’s evaluating whether to appeal the decision to the full D.C. Appellate Court. He argued that the case wasn’t just a matter of scientific debate but rather statements that, he asserts, were made knowing they were factually incorrect.

“The court is basically saying that a scientist can falsify or publish with reckless disregard for the truth false definitions or data or even lie in a scientific article with the purpose of harming or defaming another individual or group of individuals, but such actions do not fall under D.C. defamation law because the statement is published in a scientific paper rather than in a newspaper or other public forum,” Jacobson told Retraction Watch.

Defense of science

Unlike Clack’s article, which was published in a scientific journal, Mann sued Rand Simberg and Mark Steyn over statements they made in posts on blogs. Simberg compared the Penn State investigation into Mann’s research with the university’s investigation into assistant coach Jerry Sandusky, who was found guilty of sexually abusing 10 young boys over the course of 15 years. Steyn, in his post, quoted Simberg and criticized Mann’s “hockey stick graph,” which has been highly influential in climate science and energy policy, as fraudulent.

In his 2018 explanation on why he dropped his lawsuit, Jacobson cited Mann’s lawsuit in disputing that PNAS and Clack were expressing opinions or making statements they believed were factual. Jacobson insisted that since Jacobson had told them the article contained errors prior to its publication, they demonstrated a reckless disregard for the truth by publishing it anyways.

Some argued Jacobson was making a naked attempt to silence critics. In 2017, microbiologist Alex Berezow wrote in the American Council on Science and Health that Jacobson was suing “for his hurt feelings and bruised ego” and called the lawsuit “completely obscene.”

Pulitzer Prize-winning Los Angeles Times journalist Michael Hiltzik in 2018 called the lawsuit “ridiculous.”

“The discussion got sidetracked by the issue of whether research publications or courtrooms were the proper venues to hash out scientific issues. By withdrawing his case, Jacobson has given us an answer,” Hiltzik wrote.

Mann has also been criticized for trying to silence criticisms of his research with the suits against Steyn and Simberg, as well as a separate libel suit against Tim Ball, which was dismissed.

Mann told CNN that the suit was “really about the defense of science.” He claimed that the statements made about his research were false.

However, climate scientist Dr. Judith Curry wrote an expert opinion that concluded “it is reasonable to have referred to the Hockey Stick in 2012 as ‘fraudulent,’ in the sense that aspects of it are deceptive and misleading.” The report wasn’t admitted into evidence.

Terrance Corcoran, columnist for The Financial Post wrote that, following the verdict, “Mann still felt the need to tear Curry down — again. Instead of a dignified celebration of his victory, he sent out a tweet alleging Curry ‘was among those named’ as a climate change ‘denier’ in the Nature Communications Journal.”

Steyn bore the brunt of the jury’s damages determination. He was ordered to pay $1 million in punitive damages, whereas Steyn was ordered to pay $1,000.

Rupard Darwall, senior fellow of the RealClear Foundation, wrote in RealClear Energy of the various ways in which, he says, the data Mann used to construct his “hockey stick graph” was altered to hide warming periods prior to increases in carbon dioxide from burning fossil fuels.

Darwall noted that the bulk of the jury’s punishment fell upon the defendant who questioned the scientific validity of Mann’s research, which he said shows the jury’s political bias.

“Steyn has a high profile as one of the most accomplished of conservative commentators. Evidently, the DC jury decided to make an example of Steyn and discourage any public questioning of today’s consensus of human-caused climate change,” Darwall wrote.


Mann has been accused of previously trying to suppress viewpoints countering his own.

Dr. Roger Pielke Jr., professor of environmental studies at the University of Colorado at Boulder, alleges that Mann intervened in the peer-review process to get hostile reviewers assigned to a study Pielke had written in the hopes it wouldn’t get published. It was ultimately rejected.

In 2022, Mann teamed up with filmmaker Josh Fox, who produced the anti-fracking documentary Gasland, in an effort to get Michael Moore’s anti-renewable energy documentary Planet of the Humans removed from Youtube.

During the campaign on X, which was then called Twitter, Fox referred to “the 100% renewable energy plans of Stanford University and others” in condemning Moore’s film.

In Mann’s case, a jury came to believe that he’d been wronged. In Jacobson’s case, the court concluded he was motivated to silence his critics. Time will tell how these outcomes will impact critics of climate change and renewable energy research.

Just the News Spotlight