The high-profile climate scientist Michael Mann has been awarded $1m by a jury in a defamation lawsuit against two conservative writers who compared his depictions of global heating to the work of a convicted child molester.

The case stretches back 12 years. In a statement posted on Mann’s X account, one of his lawyers said: “Today’s verdict vindicates Mike Mann’s good name and reputation. It also is a big victory for truth and scientists everywhere who dedicate their lives answering vital scientific questions impacting human health and the planet.”

Mann rose to fame for a graph first published in 1998 in the journal Nature that was dubbed the “hockey stick” for its dramatic illustration of a warming planet. It showed average temperatures in the northern hemisphere changing little for 900 years, until they started to rise rapidly in the 20th century.

The work brought Mann, then at Penn State University and now at the University of Pennsylvania, wide exposure. It was included in a report by a UN climate panel in 2001 and a version of it was featured in Al Gore’s Oscar-winning 2006 climate change documentary, An Inconvenient Truth.

Emails from Mann and other scientists were leaked in 2009 in an incident known as “Climategate”, with climate denialists claiming Mann manipulated data. Investigations by Penn State and others, including an examination of the emails by the Associated Press, found no misuse of data by Mann.

Regardless, in 2012, the Competitive Enterprise Institute, a libertarian thinktank, published a blogpost by Rand Simberg that compared investigations by Penn State University into Mann’s work with the case of Jerry Sandusky, a former assistant football coach who was convicted of sexually assaulting multiple children.

“Mann could be said to be the Jerry Sandusky of climate science, except for instead of molesting children, he has molested and tortured data,” Simberg wrote. Another writer, Mark Steyn, later referenced Simberg’s article in his own piece in National Review, calling Mann’s research “fraudulent”.

Mann sued both men and their publishers. In 2021 a judge dismissed the two outlets as defendants, saying they could not be held liable, but the claims against the individuals remained.

Simberg and Steyn argued they were merely expressing their opinion.

According to the Mann legal team’s statement, the four-week jury trial in the District of Columbia superior court resulted in punitive damages of $1,000 against Simberg and $1,000,000 against Steyn.

“I hope this verdict sends a message that falsely attacking climate scientists is not protected speech,” Mann said.

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