Michael Mann is the director of the Earth System Science Center at Penn State University and the climatologist responsible for the famous “hockey stick” graph, which shows how, after 1,000 years of human history, earth’s temperature started to spike about the same time that mankind started burning fossil fuels in massive quantities. That graph, of all things, has made him a hate figure amongst the most vitriolic deniers of the link between manmade carbon emissions and climate change.

How Mann has been treated since publishing the graph shows how angry, dogmatic and vicious the debate around the evidence for anthropogenic climate change remains—to the extent that it is no longer a debate at all. In July, though, some of Mann’s critics crossed a line.

Writing in the National Review, a right-wing newspaper, Mark Steyn went all the way to calling Professor Mann a fraud. In his article, Steyn referenced and repeated an accusation in an extraordinarily offensive blog by the Competitive Enterprise Institute’s Rand Simberg that Mann was “the Jerry Sandusky” of climate science, comparing the climatologist to the former Penn State college coach convicted last year of child molestation.

Mann sued for defamation.

The National Review and CEI tried to get the case dismissed on the grounds of censorship of protected opinion, but a District of Columbia judge has ruled that the suit can proceed.

Being allowed to take the battle against skepticism to court, albeit in a single, personal case, could be an important step at a time when there seems to be a perceptible fatigue amongst some communicators of climate change; a nagging sense of worry not about their science, but about their ability to force the truth through the mists of obfuscation and vitriol that have allowed deniers to keep doubt in the public discourse. Despite an overwhelming consensus within the scientific community that carbon emissions from human activity have led to, and continue to cause, a rise in global temperatures, the minority view to the contrary is still promoted and funded by elements of the energy industry.

Amongst climate scientists, 97 percent agree that climate change is anthropogenic. Amongst the American public, that is just 40 percent.

The defamation case is in progress, so Mann is not able to talk about it to the press, but in a sense he has been here before. His book, the Hockey Stick and the Climate Wars, details the battles against business-funded skepticism of the causes of climate change.

In one particularly costly episode in 2010, the Virginia Attorney General Ken Cuccinelli began an investigation into grants received by Mann while he was an assistant professor at the University of Virginia, under the “Virginia Fraud Against Taxpayers Act.” Cuccinelli wanted, according to comments published in the Washington Post, to find out if Mann had doctored data when applying for state funding for his research.

It was the year after the “Climategate” email controversy, when leaked emails from several leading climatologists were used by skeptics to claim that there was a conspiracy to hide doubts about whether global warming data really showed correlation with carbon emissions.

In the context of the public media, it barely mattered that Mann was exonerated, nor that the emails could quite easily be explained by scientists debating evidence in search of the truth. It hardly mattered, too, that the raft of accusations against Rajendra Pachauri, the chair of the Intergovernmental Panel on Climate Change profiteered from his links to carbon trading and dashed around the world indulging his taste for expensive suits were also proved to be false. The seeds of conspiracy and doubt were sown; the denial lobby had struck their blows. Which is why taking on the comments in a public forum when they cross the line really matters.

Mann compares it to asymmetrical warfare.

“One side, us, the scientists, have to be true to our principles, have to be truthful to our audience, have to state our findings with appropriate caveats, and the other side sees absolutely no need to do that.”

Communicating the threat and cause of climate change is extraordinarily hard for scientists, in part because statistics, projections and abstractions are very difficult to wind into narratives.

Sometimes big events cause big events; sometimes imperceptible ones bring down entire systems—the climate is an Oslo Sand Pile. This chaos problem presents a very difficult narrative dilemma. Constantly looking for a straighforward cause-effect relationship is a feature of the news media. This is why coverage of stock markets is often tinged with the absurd and hard to believe—crowds are systems at a critical point. One fat finger, one misplaced tweet can cause a scale invariant collapse—up or down. It is not just that the system is irrational, it is that it is critical, and governed by the same chaotic interactions that describe the incidence and magnitude of earthquakes.

It would be incorrect to say with conviction that Hurricane Sandy itself was the direct result of climate change, even though extreme events like Sandy are going to become more frequent, or at least more probable over any given time period, because of a rise in global temperatures.

When asked: “Did climate change cause that drought”, the honest answer is not: “Yes, of course.” The answer is “Climate change made that drought more likely.”

And, of course, scientists themselves have doubts over how to interpret individual events. When the pace of global warming seems to slow, the burden is on climatologists to evaluate the evidence; when the rate of carbon dioxide released by arctic melt is lower, they have to explain why. Their opponents need only sit back and say “I told you so.”

“Proof is for mathematical theorems and alcoholic beverages. It’s not for science,” Mann says. “Science works in evidence through best explanations, most credible theories, and so in a sense we’re at a disadvantage because we have to play by the rules, the other side doesn’t… They’re not offering up credible alternatives or explanations. In most cases they’re trying to pick holes. Not real holes, just things that the public will think are holes, in the science. We are at a disadvantage.”

Bound by honesty, the scientific consensus is going to struggle to overcome this problem, appearing unable to actually back up its results with tangible events, offering, Cassandra-like, warnings of a future that will go unheeded until it is too late.

There is an easy analogue to be found in last century’s battle between medical science and the tobacco industry. There, too, the fact that no individual case of lung cancer could be attributed to smoking meant that scientists had to call on the statistics while fighting a well-organised, well-funded campaign of misinformation from industry front groups and others with a clear vested interest in the continuation of the status quo. Then, retailers associations, supposed smokers’ groups and tame politicians were co-opted into first confusing the science with doubt and latterly making pronouncements about the importance to libertarian politics of the freedom of choice—the choice to smoke.

As Mann says: “Scientists and those looking to communicate the reality of science are up against this juggernaut, this extremely well-funded, well-organised smear campaign by the most powerful industry that ever existed on the face of the earth, the fossil fuel industry.”

It has well and truly begun to pollute the politics. In the US, the world’s largest carbon emitter, there has been a dedicated campaign to politicize the debate, with conservative funders like the Koch Brothers—who, incidentally, are co-funders of “think tanks” like the Competitive Enterprise Institute that have made personal attacks against Mann—backing candidates in the Republican primaries to unseat those who have any sensitivity towards the threat, Mann says.

This promotes people like Cuccinelli, making the denial of anthropogenic climate change an issue of party dogma; an assumed symptom of a liberal conspiracy to undermine the country’s industry and weaken America. In 2010, he applied to the Environmental Protection Agency asking it to reopen its finding that greenhouse gas emissions are harmful to public health.

“We cannot allow unelected bureaucrats with political agendas to use falsified data to regulate American industry and drive our economy into the ground,” Cuccinelli said in a press statement at the time.

It is not confined to the US. There are elements of the conservative right in the UK that seek to link emissions regulations and mitigation funding to the supposedly pernicious influence of the European Union, confusing a fundamentally scientific debate with a nationalist agenda.

This kind of dogmatic approach, nailing a conspiracy theory and a misplaced sense of patriotism to the denial of the science, means that the two sides are not fighting fair.

In light of the gross provocation, the lies and the distortions, from the other side, there has to be a strong temptation to break from the requirement for rigor and simply state, baldly, that each extreme weather event, each drought or flood is the result of human action, and that each year will be incrementally worse without concrete policy and consumer action. But to do so would be to degrade the only weapon that the consensus really has to back it—the truth.

The science versus climate change deniers argument, particularly in its American context, is a strange one, bearing many of the hallmarks of a vicious, negative election campaign, with all the elements of politicking, money, vested interests and unconvincing dogma. Except that victory in this argument is not an electoral mandate. It is not schoolyard bragging rights. It is hundreds of millions of lives, hundreds of billions of dollars from the global economy—and potentially the entire future progress of human civilization. Just as the rules are asymmetrical for the opposing sides, so are the outcomes. If the deniers win, everyone loses. That hardly seems like a battle worth fighting.

“It will likely have cost us decades,” Mann says. “It will have delayed the necessary reductions in carbon emissions for decades, and we’re committing not just us, but our children and our grandchildren to far worse effects, far greater economic losses, losses when it comes to the toll taken in human lives. It’s an unfortunate reality, but I do think that in the end, science will prevail.”