Outside of the opinion polls and scientific journals, the public discourse about climate change is generally very low quality. Scientific understanding and even basic facts often fall far behind name calling and conspiracy theories. But, even by the rather low standards of the genre, a piece published at the blog of a free-market think tank was shocking—it compared a Penn State climate scientist to a convicted child molester who used to work for the university's athletics program. Those accusations were then echoed by the National Review.

The scientist in question, Michael Mann, demanded the piece be removed, and asked for a public apology. The National Review responded by threatening to use discovery to demand all of Mann's documents (which were already the subject of court cases) and proving that he was, in fact, a fraud. Now, months after those threats were exchanged, Mann's lawyers have actually filed the suit.

A misdirected focus

In many ways, the focus on Mann is a product of a very odd failure of logic. The basic outlines of anthropogenic climate change—the greenhouse effect, rising CO 2 levels, a significant rise in global temperatures—are all so well understood they could basically be considered factual.

But somehow, many people who doubt that humanity has played a role in driving the climate have become obsessed with the potential that natural variations have caused the recent rise in temperatures. In some cases, that has led to bizarre accusations that scientists haven't attempted to consider or account for drivers of natural variations (despite the fact that they make significant appearances in the IPCC's attribution chapter, where the word "natural" appears over 100 times). In the more extreme cases, advocates make these natural variations sound almost magical, as they seem to act without leaving any discernable trace on the globe.

The desire to blame natural variations has also been expressed in a desire to show rising temperatures over the last century and a half are not in any way unusual. Although this sometimes includes irrelevant references to past conditions (boy, was the Triassic hot!), some of that more appropriately focuses on conditions within the current interglacial period. And that's where Michael Mann comes in. Mann's specialty is reconstructing the global climate of the recent past based on temperature proxies like tree rings and bore holes, which capture some noisy information about the local conditions in the past. Get enough of these with a sufficiently global distribution, and you can estimate the global temperature for centuries before we had accurate thermometers.

Back in the 1990s, Mann was one of the first to attempt to perform one of these global reconstructions, and the result became iconic: the hockey stick graph, which later graced the cover of an IPCC report. Although it got him a Nature paper at the time, it's caused him little but trouble since. A substantial portion of the people who are convinced scientists are just making up the whole climate change thing have decided that, if they can just discredit Mann's work, the entire field of study will come crashing down into a confused heap.

Mann's paper, as a first attempt at this sort of reconstruction, attracted some criticism on scientific grounds. But it also attracted no end of non-scientific vitriol because it was mistakenly considered to be so central to the entire argument about climate change. Eventually, it even became the subject of Congressional hearings where climate science as a field was accused of being sloppy with statistics and too insular to notice. But the report that accused climate scientists of helping each other through peer review turned out to have been heavily plagiarized (and, ironically, was pushed into publication by a friendly editor). The National Academies of Science analyzed how the field had progressed since Mann's publication, and found that multiple studies, using improved methods, had now replicated the hockey stick result.

It might be reasonable to expect that matters would end there.

Enduring animosity

But this is climate change, where reasonable expectations don't count for much. People remain unconvinced that recent temperature changes aren't anything usual, and they have continued to attack a paper that's closing in on being 20 years old. For his part, Mann has used a book, editorials, and public speaking opportunities to defend his work and climate science in general. And, in the middle of it all, history (in many ways) repeated itself.

When e-mails were stolen from a server in the University of East Anglia, Mann's correspondence with other scientists ended up being leaked to the public. And, just as with the hockey stick, various inquiries into the validity of his work (and that of others) were launched. But all of those inquiries came to roughly the same conclusions: the e-mails were being quoted out of context, and there was no evidence of improper science or any form of a conspiracy. Once again, matters should have probably ended there.

But they haven't. Reasoning that a small collection of private e-mails made Mann look bad, the Attorney General of Virginia sued to obtain everything he sent while he was at the University of Virginia, using unspecified allegations of fraud as an excuse. That suit was rejected, and a private think tank followed suit, only to have their attempt rejected as well.

The latest round of attacks, however, was prompted by events at Mann's current institution: Penn State. That institution's sports program was rocked by a sexual abuse scandal, and a subsequent inquiry concluded the administration turned a blind eye to ongoing abuse. If they'd do that for football, the reasoning apparently goes, they'd do the same thing for a star researcher who brings in lots of grant money.

That argument was laid out in the blog of the Competitive Enterprise Institute, a free-market think tank. Its author makes a series of accusations against the institution and Mann himself, starting with the opening line: "Penn State has covered up wrongdoing by one of its employees to avoid bad publicity." Penn State's inquiry into Mann is called a "cover up and whitewash," and Mann is variously accused of "deception" and "engaging in data manipulation." But one sentence was considered so outrageous that it was later removed by the blog's editor: "Mann could be said to be the Jerry Sandusky [a child molester] of climate science, except that instead of molesting children, he has molested and tortured data in the service of politicized science that could have dire economic consequences for the nation and planet."

Those lines were quoted approvingly by a blog post at the National Review

Mann asked for their removal and apology, and threatened to sue otherwise. In response, the CEI's took the opportunity to insult Mann further ("Professor Mann’s political advocacy is no more reliable than his scientific research"). The editor of the National Review, in a column entitled "Get Lost," informed Mann that should he sue, all the e-mails that were subject to lawsuits in Virginia would be demanded during discovery. Despite that threat, the suit was filed earlier this week.

Libel and public figures

Mann faces a significant hurdle in pursuing this suit. It's very clear that he has become a public figure, which means the people he's suing need to have acted with malice when they made their statements. Typically, that's been interpreted as meaning the people who made the libelous statements knew they were wrong when they were making them, and went ahead anyway because they intended to inflict distress. Mann's lawyers argue that you don't make comparisons with a child molester unless you intend to inflict distress: "Unsatisfied with their lacerations of his professional reputation, defendants have also maliciously attacked Dr. Mann's personal reputation with the knowingly false comparison to a child molester."

But the more interesting aspect of the suit comes in the factual nature of claims that Mann's work is fraudulent. The CEI and National Review may believe these claims have merit, but Mann's lawyers argue there's no excuse for believing that at this point: "In response to these accusations, academic institutions and governmental entities alike, including the US Environmental Protection Agency and the National Science Foundation, have conducted investigations into Dr. Mann's work, and found the allegations of academic fraud to be baseless. Every such investigation—and every replication of Dr. Mann's work—has concluded that Dr. Mann's research and conclusions were properly conducted and fairly presented."

It's hard to know what to make of this argument, other than it will be fascinating if this case makes it to court. It's hard to imagine someone could believe every single investigation of Mann's work has been superficial or a whitewash; every scientific replication evidence of either luck or a conspiracy. But it's also clear (almost certainly for cultural reasons) the authors of these pieces have convinced themselves that all of this must be true. There's less here about malice towards Mann, and more about preventing a carefully constructed alternate reality from collapsing.

The authors should be happy they're not based in Australia. That country's government agencies include the Australian Communications and Media Authority and it recently issued a ruling responding to some factually challenged radio broadcasts on climate change. The Authority ordered the host and his staff to undergo training on factual accuracy, and the station needs to track its fact-checking process for six weeks afterwards.