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Michael Mann Fought Climate Denial. Now He’s Fighting Climate Doom.

June 11, 2020
by Bryan Schatz

The climatologist is taking on both the fossil fuel lobby and those who think the climate fight is futile.

ONE AUGUST AFTERNOON IN 2010, Michael Mann was opening mail in his office at Penn State University when a dusting of white powder emerged from an envelope. At first he thought it was his imagination. “I figured maybe it’s just an old dingy envelope or something,” Mann recalled. His next thought: anthrax.  

Mann bolted out of his office and shut the door, washed his hands, and called the cops. Soon, the FBI arrived. Agents retrieved the letter for testing while Mann was left to explain to stunned colleagues why there was police tape sealing his door. 

Death threats weren’t exactly the kind of thing Mann ’89 had imagined as an undergrad at Cal, when he was first thinking about a life in academia. But his career as a climate scientist had attracted some very powerful and determined enemies. Over the years, he’d gotten used to verbal attacks and idle threats, but this was on a different level. He began to worry about his family’s safety. 

In the end, the powder proved to be cornstarch, but police gave Mann a hotline number just in case. He and his wife put it on the refrigerator. 

Mann’s troubles started a decade earlier. It was 1998 and the young scientist, then a postdoc at UMass Amherst, co-authored a study with the innocuous title, “Global-scale temperature patterns and climate forcing over the past six centuries.” Published in the journal Nature that April, the paper aimed to reconstruct Earth’s temperatures going back six centuries. To derive temperatures for the half millennium before the invention of thermometers, Mann and his collaborators relied on “proxy records”—indirect temperature measurements extrapolated from things like ice cores, tree rings, lake sediments, and coral. (Up to that point, researchers had looked at one type of proxy record or another, but no one had synthesized the data in one study.) Their conclusion? Three of the past eight years had been “warmer than any other year since (at least) AD 1400.”

Climate scientists Michael Mann fought those who attacked the hockey stick graph. Now, he’s fending off those who embrace it too readily. // Illustration by Charlie Powell


The following year, the researchers extended the study back further, to AD 1000, and found much the same. For most of the last millennium there had been only minor fluctuations. Then, around the turn of the 20th century, temperatures began to rocket upwards as if the planet were running a fever. 

To climatologist Jerry D. Mahlman, the graph of the data looked like an upturned hockey stick—the long period of relatively stable temperatures formed the shaft, the last century’s spike was the blade. The image stuck, and it has been known ever since as the “hockey stick graph,” an easily graspable image that helped make the study both a lodestar and a lightning rod. The Atlantic magazine once dubbed it “The Most Controversial Chart in Science.”

The hockey stick graph gained widespread attention in 2001, after it was included in the Third Assessment Report of the UN’s Intergovernmental Panel on Climate Change (IPCC), which concluded, partly based on Mann and his colleagues’ work that, “The increase in temperature in the 20th century is likely to have been the largest of any century during the past 1,000 years.” 

The subsequent attacks were relentless. Detractors rallied for Mann’s arrest. He was accused of “scientific fascism” and called a terrorist. Critics cracked jokes about Mann-made global warming.” Marc Morano, an influential blogger who got his start under Rush Limbaugh before moving on to ExxonMobil, said Mann and other climate scientists “deserve to be publicly flogged.” Limbaugh himself argued that they should be drawn and quartered. Fox’s Glenn Beck suggested they commit suicide.

The opposition wasn’t limited to bloggers and shock jocks. As the hockey stick graph gained notoriety, studies started appearing in non-peer-reviewed journals purporting to poke holes in Mann’s work. The fossil fuel industry’s network of PR firms and political operatives joined the fight. Industry-funded websites like World Climate Report and Global Climate Coalition sought to muddy the waters, as did climate skeptic blogs like Climate Audit, run by retired mining consultant Stephen McIntyre. Before long, the climate debate was shot through with conspiracy theories and disinformation.

The messages the contrarians peddled found purchase at the highest levels of government. Phil Cooney, chief of staff of the Council on Environmental Quality in the George W. Bush administration, edited Mann’s work out of the EPA’s 2003 State of the Environment report, replacing it with a controversial study funded by the fossil fuel lobby. Also in 2003, Sen. James Inhofe (R-Okla.), then the leading recipient of oil and gas money in the Senate (he later called climate change “the greatest hoax ever perpetrated on the American people”) demanded investigations into Mann and his colleagues, and called hearings to question the entirety of climate change science. Two years later, former Rep. Joe Barton (R-Texas) sent Mann and his colleagues a threatening letter disguised as a subpoena, citing a Wall Street Journal story critical of their work as justification for what amounted to an open-ended investigation into Mann and his colleagues. 

When Mann received the powder-filled envelope, he was in the thick of another hyped-up scandal dubbed

Barton’s letter not only drew swift denunciations from the science community but also from members of his own party. “We have only to look at the failures of biological science in the former Soviet Union to understand the scientific and political costs of interference,” the late Sen. John McCain (R-Ariz.) said at the time. “The message sent by the Congressional committee to the three scientists was not subtle: Publish politically unpalatable scientific results and brace yourself for political retribution.” 

Undeterred, Inhofe would eventually call for Mann and 16 other climate scientists to be criminally prosecuted, arguing that they may have engaged in “potentially criminal behavior” punishable by prison. 

When Mann received the powder-filled envelope, he was in the thick of another hyped-up scandal dubbed “Climategate,” in which contrarians heisted more than 1,000 emails from Mann and other prominent climate scientists, took them out of context, and claimed they revealed an unparalleled level of scientific wrongdoing. (They didn’t.)

The attacks would ebb and flow, but over the years, there were a few episodes of reprieve, such as in 2006 when the National Academy of Sciences—“truly the arbiter of our scientific consensus,” as Mann put it—weighed in:

“The basic conclusion of Mann et al. (1998, 1999) was that the late 20th century warmth in the Northern Hemisphere was unprecedented during at least the last 1,000 years. This conclusion has subsequently been supported by an array of evidence that includes both additional large-scale surface temperature reconstructions and pronounced changes in a variety of local proxy indicators, such as melting on ice caps and the retreat of glaciers around the world, which in many cases appear to be unprecedented during at least the last 2,000 years.”

MANN WAS FURTHER VINDICATED in October 2007 when he was one of hundreds of scientists who shared in the Nobel Peace Prize, along with former Vice President Al Gore. Mann was one of two scientists the IPCC singled out for their personal sacrifices. Most recently, in April of this year, Mann was elected to the National Academy of Sciences.

“The debate over the hockey stick was a distraction. There is no doubt that the fossil-fuel industry has funded a widespread disinformation campaign with the objective of delaying action on global warming.”

While climate deniers have thrown everything they have at the hockey stick graph, they haven’t dented the underlying science. Indeed, there was so much consensus within the scientific community that a joke emerged: The hockey stick became a hockey team, and, over time, a whole hockey league. 

“In the end, two decades later, there’s now a huge family of these reconstructions, using different methods, different approaches, one very prominent one within the last year that extended the hockey stick back 2,000 years now, and they’ve all come to the same conclusion,” said Mann. “I think that has put the early efforts to discredit the hockey stick in the context of history. It has passed the test of time.”

But the deniers’ efforts have served a separate, and arguably more detrimental, purpose: to sow doubt. “The tactic is to create the illusion of a debate, to create a food fight,” Mann said. “They don’t need to win the food fight, they just need a food fight to happen. They throw as much mud on the wall as they can, and you simply don’t have enough time to scrape it all off.” 

Berkeley climate scientist David Romps agreed. “The debate over the hockey stick [was] a distraction. There is no doubt that the fossil-fuel industry has funded a widespread disinformation campaign with the objective of delaying action on global warming so that it can mop up profits for as many years as possible.”

Meanwhile, Mann said, the blade on the hockey stick “is getting longer.” 

MANN WASN’T THE FIRST TO BE SINGLED OUT by the fossil fuel industry as a target. James Hansen of the NASA Goddard Institute for Space Studies had that privilege after testifying before Congress in 1988 on the dangers of global warming. Ben Santer, an atmospheric scientist at Lawrence Livermore National Laboratory, also became a target, after he and co-authors wrote in the IPCC’s 1995 report that “the balance of evidence suggests a discernible human influence on global climate.” But the ferocity inflicted upon Mann was different. “What did surprise me was the vehemence of it all, the absolutely relentless chewing through this that I don’t think has happened to any study before or since,” said NASA climate scientist Gavin Schmidt.

As Benjamin Santer told a reporter in 2013, he believed the contrarians had a particular interest in attacking Mann because the hockey stick was such a potent symbol. “You go after the things that are important, that are iconic, that are visual, visceral, powerful, and easily interpretable,” Santer said. “And if you can’t attack the underlying science, you go after the scientist.”

“So what happens when suddenly the tsunami of contrarian shit is concentrated in your direction? You’re just bowled over by it. It’s extremely

None of what Mann has experienced sits well with those who know what it’s like. “There’s no reason that someone like Dr. Mann should have to face that kind of psychological stress simply because he reports accurately his scientific findings,” said journalist and climate activist Bill McKibben, who likewise has received death threats, an experience that prompted him to pen a New York Times op-ed in October 2018. While “it seems pointless to call for ‘civility’” in these times, McKibben suggested that maybe a lower bar is still achievable: “Let’s stop threatening to kill one another.” 

That may sway those without a vested interest in the outcome, but the professional campaign to kneecap climate science will always seek novel ways to do so, said David Romps. “I think the goal of these evil tactics is twofold,” he said. “The first is to tarnish Michael’s reputation, although this has failed miserably. The second is to scare other climate scientists away from being vocal, and I think this has been partially successful. Junior scientists working in climate know that they could face the wrath of the denial machine if they do not keep their heads down.”

Mann echoed this sentiment. “Undoubtedly, they saw me, the very junior, untenured scientist, as the most vulnerable.” His two co-authors on the hockey stick paper, Malcolm Hughes and Raymond Bradley, had already attained a level of prominence in science, not to mention career security in the form of tenure. He likened his experience to what happened to Benjamin Santer in the mid-1990s. “They saw him as a young, up-and-coming, and vulnerable scientist, and if they could discredit him and make an example of him, it would serve notice to any other would-be Ben Santers,” Mann said.  

“As a scientist, you don’t expect quaintness,” said Schmidt, who has known Mann since before his hockey stick days. “You go to grad school and you go to meetings and you see people disagreeing, and you see people writing papers in opposition to other people’s papers. But the basic thing is: it’s all done with a certain level of civility and in relatively good faith that allows science to progress without too much rancor.”

“So what happens when suddenly the tsunami of contrarian shit is concentrated in your direction? You’re just bowled over by it. It’s extremely stressful. Mike has mellowed a little bit, but at the time, I think this was an ordeal,” said Schmidt. 

If it hadn’t been for the mentoring of a few senior scientists, most notably from Stephen Schneider, who was a professor at Stanford University, said Mann, “I’m not sure if I could have held up.”

In blue is the original hockey stick of Mann, Bradley and Hughes (1999 ) with its uncertainty range (light blue). // Graph by Klaus Bitterman.

But over time, as the attacks mounted, he came to realize that he had no choice but to fight back. Mann has continued his research, publishing more than 200 peer-reviewed studies, but he has also embraced his role as a pugnacious public figure, regularly going toe-to-toe with his detractors through whatever avenues are available: in the media, on the Internet, at Congressional hearings, and in court. His 2012 book The Hockey Stick and the Climate Wars exposed the powerful forces attacking climate science, and their vested interests in doing so. He writes biting op-eds at the Guardian, Huffington Post, and The New York Times, is a frequent guest on news networks, and is prolific on Twitter, where he often spars with climate deniers. After one user tweeted, “87 percent of fires in Australia are arson and this is not the worse they have had,” Mann responded: “100% of your tweet is b.s.”

Mann sued the Competitive Enterprise Institute (CEI) and the National Review for defamation over articles accusing him of fraud and comparing him to Penn State coach Jerry Sandusky, who was convicted of rape and child sexual abuse. “Instead of molesting children, [Mann] has molested and tortured data in the service of politicized science,” read one CEI blog post. 

“Other people might have said, ‘I should keep my head down,’” observed Schmidt. “But Mike kind of leaned into it, and kept pushing.” 

He wasn’t the only one. In response to the contrarian blogs and online potshots, Mann, Schmidt, and others created a blog of their own, called RealClimate. “It was half debunking nonsense and half explaining concepts and reacting to stuff that was in the news,” Schmidt said. They banded together in other ways, supporting each other’s work, and at workshops, teaching each other how to better communicate the science to the public. Eventually, scientists also formed a Climate Science Legal Defense Fund to help those facing lawsuits. 

For all their efforts, the climate contrarians helped create an even greater adversary. “Partly because of what Mike went through, the science community as a whole now has far more robust defenses in terms of getting people legal help, getting people psychological help, getting people advice on what to do should these things happen to you. And since it’s happened to more people, there’s more advice to go around,” said Schmidt. 

Some climate scientists even view the attacks as a badge of honor: “I, for one, have not been a target. This probably means I have not been vocal enough,” said David Romps. “I will try harder.” 

Mann likened his and his peers’ duty to the Homeland Security motto: :If you see something, say something.”

Like most scientists, Mann once eschewed advocacy, believing that science should speak for itself. It was the job of policymakers, he felt, to decide what to do about its implications. He and many other climate scientists have shifted their attitudes in the face of ongoing attacks. Some have even become full-fledged activists. James Hansen, for one, turned to civil disobedience. In 2013, the 77-year-old NASA scientist was arrested outside the White House in a protest urging the Obama administration to halt development of the Keystone XL pipeline.

While Mann can’t quite bring himself to follow Hansen’s path, he’s not content to sit on the sidelines either. In a 2014 op-ed in The New York Times he wrote, “fighting for scientific truth and an informed debate is nothing to apologize for. … In fact, it would be an abrogation of our responsibility to society if we remained quiet in the face of such a grave threat.” He likened his and his peers’ duty to the Homeland Security motto: If you see something, say something

WHAT MANN SEES IS AN UNFOLDING climate crisis wherever he goes. At the end of 2009, he went to the Florida Keys with his parents and daughter. “It was at a particularly emotionally vulnerable time,” he said. “It was right in the heat of ‘climategate,’ when all sorts of allegations were swirling around, and there was a great uncertainty as to what would come next.” Hoping to find a reprieve on holiday, he was instead confronted by the reality of dying coral reefs and rising sea level. 

Five years later, he spent time with friends in Montana, and seized on the opportunity to visit Glacier National Park. “You couldn’t help but hear about and see the dramatic impact that climate change is having on this park whose name may have to change when there are no more glaciers,” he said. (The park boasted 150 glaciers when it was founded in 1910. Today, only 25 remain.) What’s more, he added, “You could smell smoke from the fires that were burning in Oregon and Washington that summer.” 

When I first reached Mann in March, he was several months into a sabbatical in Australia. When his plane touched down in Sydney last December, the country’s record bushfires were raging across the land. Before he started working, he took his family sightseeing. First they went to the Great Barrier Reef, which is experiencing widespread coral bleaching due to warming ocean temperatures. Snorkeling, they could see some of the damage firsthand. “And, you know, I’m thinking about the fact that I’m having this experience with my 14-year-old daughter, and she may not be able to have this experience with her children.” 

It didn’t get better. When they went to the Blue Mountains, the view was obscured by smoke from the fires. Later, he was scheduled to go to Bega, on Australia’s south coast, to appear on a show with a live audience. At the last minute, they had to move the taping to Canberra, the national capitol, nearly three hours away. The fires in Bega had become too dangerous. 

There’s another D as well, at the opposite extreme from denial, that worries Mann almost as much: Doomerism

From his hotel in Canberra, he could see the fires burning throughout the night in the hills rimming the city. A “fortuitous shift in the winds” would save it from the flames. Soon, the fires were replaced with the heaviest rainfall in 30 years. “To me, that’s what’s changed. Fifteen years ago, that wouldn’t be the case. But now there’s almost no place I can go, no experience I can have, without being reminded of how real this is,” Mann said. “And every once in a while, it sort of pierces that wall of objectivity you try to build around yourself, and it impacts me emotionally and sometimes unexpectedly.”

“The warming is pretty much as the models predicted it would be decades ago. Things are pretty much on schedule. And yet when you see it happening, you realize this isn’t just model projections. This stuff is really happening. It’s almost like the inner skeptic in you as a scientist is saying, ‘Yeah, I know the models predict this. I know the data show this. But is it really happening?’ And now the answer is yes, because you can see it with your own two eyes.”

PERHAPS BECAUSE THE FACTS ON THE GROUND are so stark, Mann said there has been a pretty dramatic move away from denialism toward what he calls “the other Ds.” With outright denial no longer tenable, the “forces of inaction” have turned to delay and deflection. But there’s another D as well, at the opposite extreme from denial, that worries him almost as much: Doomerism.

In 2017, New York magazine ran a piece by the acclaimed science journalist David Wallace-Wells called the “The Uninhabitable Earth,” which was later expanded into a book. “No matter how well informed you are,” Wallace-Wells wrote, “you are surely not alarmed enough.” To some, the piece read as an urgent call to arms, a plea to tackle climate change before it’s too late. To Mann—and many other scientists—it was a gross overreach that focused exclusively on worst-case scenarios and bent the science to a fatalistic outcome, thereby dissuading people from doing anything about it. If it’s too late, why bother? 

“He makes mistakes in his characterization and assessment of the science, but they’re not innocent,” Mann said. “The errors always reinforce his narrative of doom.” 

Others share Mann’s opinion. Seventeen scientists who analyzed the piece for Climate Feedback, an organization that reviews high-profile articles on climate science, judged its overall credibility to be “low,” and a majority of them tagged it as “alarmist,” “imprecise/unclear,” and “misleading.”

“Not enough has been done to combat climate change for sure. But to say that nothing has been done is simply false.”

But it was wildly popular, and it led to similar defeatist essays by other high-profile authors, including novelist Jonathan Franzen, who wrote in The New Yorker, “The goal [of cutting greenhouse gas emissions] has been clear for thirty years, and despite earnest efforts we’ve made essentially no progress toward reaching it.” Mann, who was contacted by a New Yorker fact checker for the story, said Franzen played fast and loose with facts and misrepresented the spread of possible warming trajectories “in a way that plays to the alarmist narrative.” He sees stories like these as practically “a new genre” in journalism, one which leads to the same place as denialism: disengagement and inaction. And he’s concerned it’s contagious. 

“Shortly after Wallace-Wells wrote that piece, Swedish activist Greta Thunberg echoed the sentiment in her speech to the World Economic Forum, declaring that ‘pretty much nothing has been done’ on climate change.” That one of leading youth activists on climate is falling prey to a certain degree of futility is alarming to Mann. “Not enough has been done, for sure. But to say that nothing has been done is simply false. It is dismissive of the actions that countries, states, cities, companies, and individuals are taking every day to move us off fossil fuels, and neglects the hard data … demonstrating that we are indeed making progress toward decarbonizing the global economy.” 

As these words went to print, Mann was waging a Twitter campaign against the latest doom project, Michael Moore’s documentary Planet of the Humans. He wrote, “I’d be happy to #MannSplain to Michael Moore why his movie is a massive display of misguided mansplaining,” and was quoted in the Guardian as saying that the film contained “various distortions, half-truths and lies” in its attempt to both sound the alarm on climate and cast the green movement as hypocritical and ineffective.

Even with the Trump administration pulling out of the Paris climate agreement, Mann said, the United States may well meet its Paris obligations, “because of the progress that’s being made at the local level, at the state level, by companies.” As for China, Mann said they “are going to exceed their commitments.” 

David Romps echoed Mann’s sentiments: “To those who say we are already doomed and so there is no point to switching away from fossil fuels, let me be clear: As bad as the warming has been, it is only one-tenth of the warming we are capable of causing, which would be a hellishly altered Earth. Yes, there is cause for mourning: By failing to act over the past 30 years, we have caused irreparable harm to our climate. But that is not an excuse for wrecking the climate even further for all generations to come.” 

Right now, the fossil fuel industry has bought some time, Mann said, but those days are numbered.

But while the doomers concern Mann, at least they’re believers. The threat they pose still pales in comparison to that of President Trump and his administration, which has repeatedly dismissed global warming as a hoax. Mann rattled off a list of steps the White House is taking to undo progress on the climate, everything from resuscitating a moribund coal industry to making America “one of a handful of petro states.” Just about the time he was starting to sound like a true doomer himself, however, he brightened. “But I’m convinced that that is not a permanent obstacle.” 

Right now, the fossil fuel industry has bought some time, Mann said, but those days are numbered. “I’m committed to the belief that there will be a moment, perhaps not in the too distant future, where the political winds writ large will be more favorable. I think at that point, we will see the tipping point on climate action, because the groundwork has been laid, the scientific case is compelling, nature is compelling, nature is communicating the profound impacts of climate change directly to us, and that means we’ll be able to hit the ground running.”

Bryan Schatz is a reporter in Oakland. Find him on Twitter at @bryanschatz.

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