A Major Defamation Lawsuit Brought by a Climate Scientist Proved Successful. Here's What to Know.

Last week, climate scientist Michael Mann emerged victorious in a lawsuit against two conservative commentators who were accused of defaming him by challenging his research and likening him to a convicted child molester. The jury awarded Mann over $1 million in a landmark case that is seen as a warning against attacking scientists in controversial fields such as climate science and public health.

The lawsuit originated from a 2012 blogpost by the Competitive Enterprise Institute (CEI), a libertarian think-tank in Washington D.C. In the post, policy analyst Rand Simberg compared Mann, then at Pennsylvania State University, to Jerry Sandusky, a former football coach at the same university convicted of sexually assaulting children. The post accused Mann of manipulating data for political purposes. The comparison was later reproduced by Mark Steyn in a blog for the conservative magazine National Review. Mann filed a libel suit against Simberg, Steyn, CEI, and National Review in 2012.

Following a three-week trial, the jury ordered Simberg and Steyn to pay $1 in compensatory damages. Additionally, Steyn was ordered to pay $1,000,000 in punitive damages, and Simberg was ordered to pay $1,000. The court had previously ruled that neither CEI nor National Review could be held liable for the blogposts as Simberg and Steyn were independent contributors, not employees.

Mann gained recognition for reconstructing global temperature trends over a 1,000-year period. His work included the “hockey-stick graph,” illustrating a gradual decline in temperatures followed by a sharp spike in the twentieth century. This graph became a symbol of human impact on the climate system. Mann's work made him a target for climate-science deniers, and he faced criticism and investigations, including a controversial probe by Virginia's then attorney-general in 2010.

The jury's decision comes at a time of heightened political polarization, leaving climate scientists vulnerable to verbal abuse and harassment, both online and offline. A global survey from last year indicated the physical and emotional toll scientists are enduring due to such attacks.