Climate Scientist Michael Mann Files Defamation Lawsuit Against Climate Denial Writers

On October 22, 2012, climate scientist Michael Mann filed a defamation lawsuit against Rand Simberg (a former scholar at the Competitive Enterprise Institute) and Mark Steyn (who wrote for National Review), after they published blog posts comparing him to Jerry Sandusky, the former Penn State football coach convicted of child molestation. The lawsuit challenged years of coordinated harassment targeting Mann for his “hockey stick” climate graph showing dramatic 20th century warming, seeking to hold climate deniers legally accountable for character assassination campaigns against scientists.

Comparing Climate Scientists to Child Molesters

Simberg wrote in a Competitive Enterprise Institute blog post that Mann “molested and tortured data” to produce his climate research, explicitly invoking the Penn State Sandusky scandal. Steyn amplified the comparison in National Review, defending Simberg’s characterization. The posts represented the culmination of years of harassment Mann faced after publishing research showing human-caused climate change. Climate denial organizations had systematically attacked Mann’s reputation, seeking to discredit climate science by destroying individual scientists’ credibility through character assassination rather than engaging with research findings.

Twelve-Year Legal Battle Begins

The lawsuit initiated what would become a twelve-year legal odyssey, with climate denial advocates citing First Amendment protections for their attacks on Mann’s reputation. The defendants argued that comparing a scientist to a convicted child molester constituted protected opinion rather than defamatory false statements of fact. In 2021, Judge Alfred Irving ruled that the Competitive Enterprise Institute and National Review as publishers could not be held liable, finding they did not meet the “actual malice” standard required for public figures suing for defamation. However, the case against individual writers Simberg and Steyn continued.

Significance of Mann’s Legal Challenge

Mann’s willingness to pursue the lawsuit despite the personal cost—years of legal battles, continued harassment, and professional distraction—demonstrated determination to impose consequences on those weaponizing defamation against climate scientists. The lawsuit sent a message that there were limits to acceptable attacks on researchers, even in the context of politically contentious science. Climate denial organizations had operated for years under the assumption they could say anything about scientists without legal consequences. Mann’s lawsuit challenged that assumption, potentially creating accountability for the most extreme harassment tactics.

Broader Pattern of Scientist Intimidation

The defamation suit occurred within a broader context of systematic harassment of climate scientists. Following the 2009 Climategate manufactured scandal, scientists faced death threats, subpoenas from hostile politicians, and coordinated campaigns to damage their careers. The Heartland Institute’s 2012 billboard comparing climate scientists to the Unabomber exemplified this pattern. Mann became a particular target because his research was so influential and his “hockey stick” graph so effective at communicating climate change to public audiences. By attacking Mann personally, climate denial organizations sought to intimidate other scientists from prominent public communication about climate science.

Significance

Mann’s 2012 defamation lawsuit represented a watershed moment in climate scientists fighting back against systematic harassment campaigns funded by fossil fuel interests. For years, climate deniers had operated with impunity, assuming scientists would be too intimidated or professionally constrained to pursue legal action. Mann’s decision to sue—despite the personal and professional costs—challenged this dynamic and signaled that the most extreme character assassination tactics might face legal consequences. The case’s twelve-year duration revealed both the difficulty of achieving accountability for scientist harassment and Mann’s extraordinary persistence in seeking justice. The lawsuit’s eventual outcome would have implications far beyond Mann’s individual case, potentially affecting how climate denial organizations calibrated their attacks on scientists in the future.