University of Pennsylvania environmental sciences professor Michael Mann, one of the world’s leading experts on global warming, has won a $1 million (£800,000) defamation verdict against right-wing activists who falsely accused him of data manipulation.

An academic unusual for his commitment to fighting decades of climate misinformation in arenas of law and public opinion, Professor Mann secured the verdict in the local court in Washington, DC, against bloggers Rand Simberg and Mark Steyn.

The victory stands as an important milestone for researchers long disparaged by online political actors, Professor Mann said afterwards.

“I harbour no illusions that it will stop climate denier trolls on social media,” he told ̽����Ƶ. “But I do think it may bring pause to media figures making false attacks against scientists whose work they may not like for purely political or ideological reasons.”

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In 2021, Professor Mann lost a lawsuit in the same venue, the District of Columbia Superior Court, that he brought against the organisations that published the writings by Mr Simberg and Mr Steyn, the Competitive Enterprise Institute and National Review. The professor’s team has been pursuing an appeal of that defeat, while Mr Steyn’s side has promised to appeal the loss to Professor Mann.

For Professor Mann, such political battles go back decades, to the late 1990s, when he was part of a team at the University of Massachusetts Amherst that demonstrated the magnitude of human-caused planetary warming by compiling data showing the sharp and major uptick in global temperatures at the tail end of past 900 years – featuring a chart known for its shape as a hockey stick – that matches the current era of the accelerated burning of fossil fuels.

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His work was later misrepresented through excerpts of email exchanges stolen from the University of East Anglia and presented by right-wing activists to suggest attempted deceit. While he was at the University of Virginia, he repeatedly defeated legal attempts by the state’s right-wing attorney general to portray his climate investigations as evidence of grant fraud. While he was at Pennsylvania State University, Mr Simberg and Mr Steyn wrote blog filings comparing him to Jerry Sandusky, Penn State’s infamous child-predator former football coach, by saying that Professor Mann “molested and tortured data” in his climate analyses.

The trial against the two bloggers in DC Superior Court lasted four weeks. The six-member jury deliberated for one day before it unanimously sided with Professor Mann. Professor Mann contended at trial that he lost research opportunities because of the attacks, while Mr Simberg and Mr Steyn argued that his career appeared strong. The jury awarded the professor $1 in compensatory damages and $1 million in punitive damages.

Professor Mann moved in 2022 to Penn, where he is director of the Centre for Science, Sustainability and the Media. He has also become an active participant in political debates about global warming, writing several books on the topic, co-founding the RealClimate website, and regularly engaging in media opportunities on climate science.

paul.basken@timeshighereducation.com