One morning in July 2012, climate scientist Michael Mann woke up to a terse email from a fellow scientist.
“Shit,” said the message from Phil Plait, astronomer and science communicator. “This is truly the most horrible thing I have ever seen said about a climate scientist. “If someone wrote this about me, I would call a lawyer.”
A conservative media outlet and a right-wing research organization had published comments comparing Dr. Mann, then a professor at Pennsylvania State University, to Jerry Sandusky, the former Penn State football coach convicted of sexually assaulting several boys. The writers claimed that Dr. Mann had created fraudulent charts and accused the university of mishandling investigations into both the coach’s crimes and the scientist’s investigation.
In fact, Dr. Mann called a lawyer. He sued the writers and their publishers for defamation and slander. Now, 12 years later, after a pinball ride through the obstacle course of free speech and defamation law, the case is being tried in the Superior Court of the District of Columbia. Only the two writers are being tried individually. A verdict is expected Wednesday.
“For me, to be compared to Jerry Sandusky, as the father of a 6-year-old girl, was perhaps the worst thing I have ever experienced in my life,” Dr. Mann testified in court on January 24. “I felt like an outcast in my own community.”
The court case has unfolded during a period in which open denial of climate science has declined, but the integrity of scientists has become a greater target.
“The nature of climate denial has changed,” said Callum Hood, head of research at advocacy organization the Center for Countering Digital Hate. The group recently released a report analyzing YouTube videos and found that personal attacks on scientists are now one of the most common types of online content that dismisses climate change.
The lawsuit has drawn the attention of climate scientists and jurists, among others. This trial marks one of the few cases in American courts in which a climate scientist has taken the stand to defend his research, according to Michael Gerrard, faculty director of the Sabin Center for Climate Change Law at the University of Columbia.
“It’s a rare case where a climate scientist is fighting deniers,” said Gerrard, who is also a board member of the Climate Science Legal Defense Fund, which previously helped Dr. Mann with a different legal strategy. battle.
Because Dr. Mann is legally considered a public figure, he must clear a higher bar than most people would in order to win a defamation lawsuit. He faces the difficult task of proving that the authors he sued knowingly lied in their writings. The authors have argued that his posts simply express opinions. His editors have also unsuccessfully petitioned the Supreme Court to review the case.
Katharine Hayhoe, chief scientist at The Nature Conservancy and professor at Texas Tech University, said Dr. Mann’s case resonates with other climate scientists. “I can’t go a day without being attacked,” she said. “He is fighting for all of us.”
In court, Dr. Mann defends his most famous research, which was published in the late 1990s and showed that average temperatures in the Northern Hemisphere rose so sharply in recent decades that the graphs looked like the shape of a stick. hockey.
The research came under fire in 2009 in an incident known as “Climategate”, when hackers broke into a computer server at the University of East Anglia’s Climate Research Unit and published thousands of emails between scientists, including Dr Mann. Skeptics seized on the emails to claim that he had manipulated data to exaggerate the hockey stick graph.
Penn State investigated his research, as did the National Science Foundation, the Department of Commerce and others. All cleared Dr. Mann of misconduct. Both before and after the protest, other scientists replicated his findings using different data sources and statistical methods.
The matter appeared resolved until 2012, when Sandusky was convicted and the former director of the Federal Bureau of Investigation released a report saying the Penn State administration had failed to stop the coach’s criminal actions.
The day after that report was published, Rand Simberg, then an adjunct academic at the Competitive Enterprise Institute, posted a blog post on the think tank’s website comparing Dr. Mann to Mr. Sandusky. “You could say that Mann is the Jerry Sandusky of climate science, except instead of sexually abusing children, he has sexually abused and tortured data in the service of a politicized science that could have dire economic consequences,” Simberg wrote.
A few days later, Mark Steyn, an author and later guest host on conservative radio and television shows, reposted part of Simberg’s National Review post online. “Michael Mann was the man behind the fraudulent climate change ‘hockey stick’ graphic, the real ringmaster of the tree ring circus,” Steyn added in his own commentary.
Before long, Dr. Mann filed his lawsuit.
The scientific consensus on climate change has been clear for 20 years. A 2004 paper that reviewed more than 900 scientific studies on climate change found none that rejected the idea that human activity is producing greenhouse gases that are warming the planet.
But public acceptance of that fact has fluctuated.
In 2008, 71 percent of Americans acknowledged that climate change was occurring, according to a long-running biannual survey conducted by the Yale Program on Climate Change Communication and George Mason University. But between 2008 and 2010 (the years before and after Climategate), the share of Americans accepting climate change fell to 57 percent.
He has since recovered. A 2023 survey by Yale and George Mason found that 72 percent of Americans accepted that climate change is happening.
Research on climate skepticism, denial, and campaigns to delay climate action has also advanced in recent years. In 2021, an international group of researchers trained a machine learning model to classify climate-related claims in 255,000 documents drawn from conservative think tank websites and popular blogs published over the past 20 years. Included in this data set was Mr. Simberg’s post about Dr. Mann.
The study, published in the journal Scientific Reports, classified the claims into five broad categories: global warming is not happening; human greenhouse gases are not causing global warming; climate impacts are not bad; climate solutions will not work; and the climate movement/science is not trustworthy.
The model labeled the claims in Mr. Simberg’s blog post under the category “climate movement/science is unreliable,” according to an analysis provided by Travis Coan, a computational social scientist at the University of Exeter and an author of the study.
Within this category, scientists are even more important targets than activists or politicians, said co-author John Cook, a psychology researcher at the University of Melbourne. Attacks on scientists are “actually one of the most prevalent forms of climate misinformation,” he said.
Claims that “climate solutions don’t work” have also been gaining importance, now accounting for more than half of claims coming from conservative research organizations, according to his group’s research.
No matter the form, all of these claims share the goal of delaying climate action, Dr. Cook said. “They try to get there by different routes.”
Building on the 2021 study, the Center for Countering Digital Hate’s recent report used the same methods to analyze 12,000 YouTube videos posted over the past six years. The researchers found that what they call “old denial” (claims that global warming is not happening or is not caused by humans) now accounts for just 30 percent of all dismissive claims, down from 65 percent in 2018.” , which includes attacks on scientists and misinformation about solutions, now accounts for 70 percent of these claims, up from 35 percent in 2018.
A spokesman for the Competitive Enterprise Institute declined to comment on the lawsuit. Mr. Simberg’s lawyer, Mark DeLaquil, said: “We don’t believe this case is really about climate science. “We believe this is about the right of people to express their opinions freely, even when they disagree with government reports of the kind that Dr. Mann claims exonerates him.” A lawyer assisting Mr. Steyn, who represents himself in court, also declined to comment for this article. When asked for comment, National Review editor-in-chief Rich Lowry pointed to an editorial published at the beginning of the essay in January.
Regardless of the outcome, legal experts say this lawsuit is important not only for climate science, but also for defamation and free speech law.
“The case sits at the intersection of some of our toughest questions,” said RonNell Andersen Jones, a law professor at the University of Utah. Courts must balance people’s rights to express their opinions freely, while avoiding lies that damage people’s reputations, he said.
If Dr. Mann wins, his case would show that “defamation law really has some teeth,” said Sonja West, a law professor at the University of Georgia. If he loses, the case could “fuel this broader debate about how strong our First Amendment rights are.”