Opinion | A Climate Scientist’s Defamation Victory Rebuts Attacks

The climate is warming. Polar ice is melting, glaciers are receding, the chemistry of the ocean is becoming dangerously acidic, sea levels are rising. All of this and more are consequences of the greenhouse gases we continue to emit into the atmosphere, where they trap and radiate heat that would otherwise escape into space.

Those are facts, not conjectures. Yet the scientists researching the fallout from that inconvenient fact, established more than 100 years ago, continue to face attacks that threaten their research, reputations and livelihoods.

One of us, Michael Mann, is just such a scientist. Twelve years ago, he found himself accused of research fraud for his work documenting the rapid rise of Earth’s temperature since the early 20th century.

An adjunct scholar at the time at the Competitive Enterprise Institute, which has said it “questions global warming alarmism,” compared Dr. Mann on a blog hosted by the institute to a convicted sex offender. “Instead of molesting children,” the post read, “he has molested and tortured data in the service of politicized science.” Then a conservative writer republished parts of that post on a blog hosted by National Review and added that Dr. Mann was “behind the fraudulent climate-change ‘hockey stick’ graph.”

Last week, after a decade-long journey through the court system, a jury in Washington, D.C., found that both writers were liable for defamation. We hope this sends a broader message that defamatory attacks on scientists go beyond the bounds of protected speech and have consequences. The jury awarded just one dollar in compensatory damages from each defendant, and punitive damages of $1,000 against one defendant and $1 million against the other.

However, we lament the time lost to this battle. This case is part of a larger culture war in which research is distorted and the truth about the climate threat is dissembled.

The assault on climate science has grown broader and more sophisticated. Rachael Lyle-Thompson, a lawyer for the Climate Science Legal Defense Fund, which has supported Dr. Mann in the past, warned recently that sweeping and “invasive open records requests” to harass and intimidate and “other misuse of the legal system” continue to “threaten climate scientists’ ability to freely conduct research and openly share it with the public.”

And the attacks have expanded to other frontiers of science. Witness the ongoing assault on public health experts such as the doctors Anthony Fauci and Peter Hotez, who have sought to address the Covid-19 pandemic. Or the false claims about adverse health effects from wind turbines. Or efforts by the Trump administration to limit the scientific and medical research that the government can use to determine public health regulations. Or rollbacks of environmental regulations. The list, unfortunately, goes on.

It is in the context of this broader war on science that our recent trial victory may have wider implications. It has drawn a line in the sand. Scientists now know that they can respond to attacks by suing for defamation.

A scientist defamed can publish a thousand peer-reviewed articles in the effort to clear his or her name, but when scientists and lawyers join forces, disinformation can more readily be defeated. What’s disheartening is that it took more than a decade and countless hours by a team of lawyers to win a jury verdict in our case when the verdict on human-caused global warming was rendered decades ago.

Nearly 60 years ago, in fact, scientists warned President Lyndon Johnson that the continued combustion of fossil fuels would cause irreversible warming of the Earth’s atmosphere, with consequences we are seeing today. Concentrations of carbon dioxide then were at 320 parts per million in the atmosphere, compared to preindustrial levels of approximately 280 p.p.m.

Three decades later, with atmospheric carbon dioxide at 370 p.p.m., Dr. Mann, then a young postdoc, and two veteran climatologists, Raymond Bradley and Malcolm Hughes, published the first version of a graph that resembled an upturned hockey stick.

The handle of the stick charted the relatively constant temperatures of preindustrial times, while the upturned blade showed a rapid warming that began with the Industrial Revolution. To assemble the graph, they used natural temperature archives such as tree rings, corals and sediment and ice cores to estimate global temperatures back in time. The hockey stick graph soon became what a 2013 article in The Atlantic called “the most controversial chart in science.”

“Climate deniers threw everything they had at the hockey stick,” the author, Chris Mooney, now a climate reporter at The Washington Post, wrote. They failed to disprove it — but “they certainly sowed plenty of doubt in the mind of the public,” he noted.

Which, of course, was the point. And that brings us back to our case.

In 2012, with atmospheric carbon dioxide having risen to nearly 400 p.p.m., the two blog posts attacking the hockey stick graph appeared, comparing Dr. Mann, then a professor at Penn State, to Jerry Sandusky, an assistant football coach at Penn State who had been convicted of abusing young boys.

As a jury has now decided, those posts were defamatory and were published with actual malice — meaning the defendants either knew the allegations were false or showed reckless disregard for the truth, a difficult hurdle for plaintiffs considered public figures to clear. But we did. And the hockey stick graph in the meantime has become firmly ensconced in the wall of evidence that burning fossil fuels is warming the planet at a pace and scale unseen.

Yet the machinery of disinformation, waged in part by the fossil fuel industry, continues to seed doubt, divert attention and delay action. Indeed, one of the defendants said in court that he stood by “every word I wrote about Michael Mann” and “his fraudulent hockey stick.” Both defendants are likely to appeal.

As of Tuesday, atmospheric concentrations of carbon dioxide had hit 424.20 p.p.m., levels not seen for at least three million years, when Earth was warmer and the seas were much higher.

Clean energy solutions are readily available. But meaningful action in the United States, one of the world’s biggest carbon emitters, is in jeopardy of being blocked or slowed if a significant portion of the electorate does not accept the basic scientific facts and understand their implications. Voters should keep this in mind when they go to the polls later this year. With climate science still under attack and atmospheric carbon dioxide concentrations increasing, we’re running out of time.