The Hockey Stick and the Climate Wars

Dispatches from the Front Lines

Michael Mann

• Publisher: Columbia University Press
• Year: 2012
• ISBN:
  9780231526388
• Topic: Política y relaciones internacionales
• Subtopic: Política medioambiental y energética

The ongoing assault on climate science in the United States has never been more aggressive, more blatant, or more widely publicized than in the case of the Hockey Stick graph—a clear and compelling visual presentation of scientific data, put together by MichaelE. Mann and his colleagues, demonstrating that global temperatures have risen in conjunction with the increase in industrialization and the use of fossil fuels. Here was an easy-to-understand graph that, in a glance, posed a threat to major corporate energy interests and those who do their political bidding. The stakes were simply too high to ignore the Hockey Stick—and so began a relentless attack on a body of science and on the investigators whose work formed its scientific basis.

The Hockey Stick achieved prominence in a 2001 UN report on climate change and quickly became a central icon in the "climate wars." The real issue has never been the graph's data but rather its implied threat to those who oppose governmental regulation and other restraints to protect the environment and planet. Mann, lead author of the original paper in which the Hockey Stick first appeared, shares the story of the science and politics behind this controversy. He reveals key figures in the oil and energy industries and the media frontgroups who do their bidding in sometimes slick, sometimes bare-knuckled ways. Mann concludes with the real story of the 2009 "Climategate" scandal, in which climate scientists' emails were hacked. This is essential reading for all who care about our planet's health and our own well-being.

Chapter 1

Born in a War

The balance of evidence suggests that there is a discernible human influence on climate.

—The contentious sentence in “Summary for Policy Makers,” IPCC Second Assessment Report (1995)

It is November 27, 1995, several years before my colleagues and I published our “hockey stick” study. Bill Clinton has been president for nearly three years. The Dow Jones Industrial Average just passed the 5,000 mark for the first time. The TV series E.R., created by novelist Michael Crichton, is the top-rated show on television.

In Madrid, Spain, the Intergovernmental Panel on Climate Change (IPCC) is holding the final plenary meeting for the Second Assessment Report, the purpose of which is to summarize the consensus among scientists regarding the extent of humanity’s impact on Earth’s climate. At a nearly identical latitude on the other side of the Atlantic, I am working on my Ph.D. dissertation in New Haven, Connecticut. I am oblivious to what is taking place in Madrid; I’m just trying to finish up my research in time to defend my dissertation the coming spring and begin a career as a professional climate researcher.

My research at the time focused on the importance of natural variability—that is, the role of nature, not man—in explaining changes in Earth’s climate. The one scientific article I had submitted for publication that touched on the topic of human-caused climate change would, ironically, a few months later be hailed by those who contest the proposition that humans play a significant role in observed climate changes. (That article simply demonstrated a relatively minor inconsistency between theoretical climate model predictions and actual climate observations.)¹ I was especially interested in the role that natural oscillations in the climate system might have played in observed changes in climate during the modern observational era of the nineteenth and twentieth centuries. My first-ever article analyzing climate proxy records had just been published a week earlier.² In that article, my coauthors and I showed that these natural oscillations persist over many centuries and might be more important than many scientists had acknowledged in explaining certain modern climate trends. This work, in another twist of irony, would also be celebrated by contrarians in the climate change debate, who were ostensibly unaware that both natural and human influences on climate can and almost certainly do coexist. I myself did not doubt that humans were changing the climate; the extent of evidence was already significant. I had simply chosen to focus in my research on the issue of natural climate variability.

Meanwhile, back in Madrid at the IPCC plenary, a fierce argument had broken out between the scientists crafting the report and government delegates representing Saudi Arabia, Kuwait, and some other major oil exporting nations that profit greatly from societal dependence on fossil fuel energy and, according to the New York Times, had “made common cause with American industry lobbyists to try to weaken the conclusions” of the report.³ The tussle was over whether one could state with confidence that human-caused climate change was already observable. The scientists argued that “the balance of evidence suggests an appreciable human influence on climate” because only when human impacts were included could the rise in temperature over the past century be accounted for. The Saudi delegate complained that the word appreciable was too strong. He demanded weaker wording.

For two whole days, the scientists haggled with the Saudi delegate over this single word in the “Summary for Policy Makers.” They debated, by one estimate, nearly thirty different alternatives before IPCC chair Bert Bolin finally found a word that both sides could accept: “the balance of evidence suggests a discernible human influence on climate.” The term discernible established a middle ground by suggesting that climate change was indeed detectable, as the scientists argued, while acknowledging that humanity’s precise role in that change and its magnitude were still subject to dispute—a concession that no doubt pleased the Saudi delegate. This sentence would go on to become famous or, in some circles, infamous. The fact that two entire days at the final plenary were devoted to debating a single word in the report’s summary gives you some idea of how contentious the debate over the reality of human-caused climate change had become by 1995.

Why did the scientists care so much about the wording? What would be the harm, after all, if the wording were weakened a bit? I suppose it comes down to how deeply scientists care about getting things right. Details matter, and we argue passionately with each other about them. We don’t suffer perceived inaccuracies lightly, and more than anything else, we don’t like being misrepresented. The fact that the science in this case might have deep real-world consequences only amplified these natural inclinations.

Among the scientists who fought hard against any watering down of the report’s key conclusion was Ben Santer, a climate specialist who works for the Department of Energy’s Lawrence Livermore National Laboratory in California. The recipient of a coveted McArthur “genius” award in recognition of his groundbreaking contributions to our understanding of climate change, Santer was a primary author on a series of important papers establishing the human role in observed climate change. As such, Santer was in a better position than anyone—and certainly than a bureaucrat with a political agenda—to assess the level of scientific confidence in concluding that human activity was changing the climate.

As it happens, I had met Santer for the first time a little more than a year earlier, in July 1994, at a two-week workshop on climate science at the National Center for Atmospheric Research. I was attending the workshop as a graduate student invitee, and Santer was one of the invited speakers. I asked him a question about certain details of his analysis following his presentation. His response came across as a bit defensive, as if he perceived my question as an attack. Only later would I understand why.

Santer’s work on climate change detection, unbeknownst to me, had been under increasing attack from contrarians in the climate change debate. In 1994, for example, his findings regarding the match between observed and model-predicted surface temperature changes was criticized⁴ by Patrick Michaels, a University of Virginia climate scientist who edited the World Climate Report,⁵ a newsletter with fossil fuel industry funding⁶ that featured criticisms of mainstream climate change research.

The attacks against Santer were ratcheted up dramatically following the November 1995 IPCC plenary. In February 1996, for example, S. Fred Singer, the founder of the Science and Environmental Projection Project and a recipient over the years of substantial fossil fuel fund-ing,⁷ published a letter attacking Santer in the journal Science.⁸ Singer disputed the IPCC finding that model predictions matched the observed warming and claimed—wrongly—that the observations instead showed cooling. Singer went further. He claimed that inclusion of Santer’s work in the report violated IPCC rules because the work hadn’t yet been published. In fact, the IPCC rules did not require a work cited to be published at the time of the report; if it did, the lag time involved in getting a publication to print would essentially render the report obsolete on arrival. The IPCC requirement was simply that the work be available to reviewers upon request, which Santer’s work was. Moreover, a substantial component of the research in question had been published.

Meanwhile, the Global Climate Coalition (GCC), a group also funded by the fossil fuel industry,⁹ circulated a report to Washington, D.C. insiders accusing Santer of abusing the peer review system and of “political tampering” and “scientific cleansing”—a charge that was especially distasteful given that Santer had lost relatives in Nazi Germany.¹⁰ The purported basis of these allegations? At the request of the IPCC leadership after the Madrid plenary, Santer, as lead author on an IPCC chapter, had removed a redundant summary so that his chapter’s structure would conform to that of the other chapters, all of which had summaries only at the beginning.

A few months later, Frederick Seitz, the founding chairman of another industry-funded group,¹¹ the George C. Marshall Institute, published an op-ed in the Wall Street Journal repeating the same charges. While the paper’s editors did eventually publish Santer’s rejoinder, they in effect neutered his response by editing his words beyond recognition and removing the names of the forty colleagues who had cosigned the letter, thus leaving Journal readers with the misleading impression that Santer stood alone in his defense against the specious charges.¹²

With the help of sympathetic media outlets such as the Wall Street Journal, climate change deniers were able to spread false charges about Santer faster than he—or his colleagues—could possibly hope to refute them. The practice of isolating someone like Santer to make an example of an individual scientist—what I call the “Serengeti strategy”—is a tried-and-true tactic of the climate change denial campaign. The climate change deniers isolate individual scientists just as predators on the Serengeti Plain of Africa hunt their prey: picking off vulnerable individuals from the rest of the herd.

The Santer episode encapsulates the toxic and incendiary environment that existed, largely unbeknownst to me, at the time that I was finishing my Ph.D. and preparing to enter the world of climate research. Little did I know that similar attacks might be made against me just a few years hence, when my work, like Santer’s, would be featured as a major pillar of evidence by the IPCC.

Tricks and Treats

It is late December 1974. I’ve just turned nine, and, as usual, my family and I are celebrating my birthday with relatives in Philadelphia. For more than a year now, I’ve been pestering my Uncle Paul—an artist and successful entrepreneur to whom I’d always looked for wisdom on all matters of life—to explain what it means to go faster than the speed of light. I was intrigued by such “gee whiz”—but ultimately scientific—concepts. For my birthday that year, Uncle Paul had given me a copy of a popular novel considered inspirational at the time, with an inscription indicating that it would answer my questions. I enjoyed the book, though to this day I can’t figure out what it had to do with warp speed, time travel, or any related topics. But I know that already by that age I was fascinated with the world of science.

Math and science were the subjects that had always come most easily to me; perhaps having a father who was a college math professor had something to do with it. In high school, when other kids were partying on Friday nights, I was hanging out with my computer buddies writing programs to solve challenging problems. In fall 1983, after having seen the movie War Games, I became determined to write a self-learning tic-tac-toe computer program, just as in the movie, a program that could learn from its mistakes, a rudimentary type of artificial intelligence. The movie carried a thinly veiled lesson about the futility of global thermonuclear war: There can be no winner in a tic-tac-toe game expertly played; if neither player makes a mistake, the game will always result in a tie. Perhaps if the computer—in the movie, it had seized control of America’s missile program and was preparing to launch a massive nuclear attack—could be brought to understand this paradox, it could recognize the futility of nuclear war. For me at the time, however, it was just an interesting and challenging computer problem to tackle.

Machine learning of this sort was in principle relatively straightforward. The real challenge was in how to go about constructing an algorithm—a set of operations or calculations, here in the form of a computer program—to solve the problem as efficiently and elegantly as possible. I had the computer play itself, just like in the movie. That was the easy part. In the beginning, I simply had it make random moves every turn. When it lost to itself, however, I would store both the final and previous configurations of the tic-tac-toe board in a “blacklist”—moves that would no longer be available to the computer.¹³ The blacklist was used to ensure that the computer, while it continued to make random moves, would not make the same losing move again; in this way it would gradually “learn” how to play tic-tac-toe.

In practice, it might take a very long time for the computer to become skilled enough to avoid losing because there are so many possible sequences of moves, and the program gets slower and slower as it has to scan an increasingly long list of disallowed moves before each turn. But I discovered a “trick”—the term scientists and mathematicians often use to denote a clever shortcut to solving a vexing problem—to get the computer program to learn much faster. The trick was to exploit the concept of symmetry. A tic-tac-toe game is the same no matter how you rotate the board, whether you flip it vertically or horizontally, or whether you switch the role of Xs and Os. When you take that symmetry into account, there are actually many fewer truly unique board configurations and many fewer losing moves that need to be stored in a blacklist. Now I could get the computer to become unbeatable in tic-tac-toe far more readily. The adrenaline rush, for the scientist, comes from finding tricks that make a problem easier to crack. That—and eating pizza with my friends—was my idea of a fun Friday night.

A Random Walk

A year later, in August 1984, as Ronald Reagan was completing his first term in office and Michael Jackson’s Thriller was the top-selling record album, I headed off to college at the University of California, Berkeley (UC Berkeley). In part, I must confess, I was looking to get away from the harsh Amherst, Massachusetts, winters I’d endured for the first eighteen years of life, but I was also attracted by the school’s reputation as one of the world’s leading scientific research institutions. I chose to major in physics, with a second major in applied math. The summer following my freshman year, I began doing research in theoretical physics that emphasized the computational approaches to problem solving I so enjoyed.

The project I was working on bore some resemblance to the tic-tac-toe problem that had captivated me in high school; it too involved the concept of randomness. The project employed what is known as a Monte Carlo method, named for its resemblance to a casino game—a method that I would make use of years later in my climate research. Much as gamblers in Monaco’s famous casino town engage in random rolls of the dice in hope of monetary reward, scientists generate random numbers on a computer in hope of simulating processes in nature that have a random component.

One example is the molecular interactions that govern the behavior of a solid or liquid. While the fluctuations of the individual molecules are random in nature, external conditions—the ambient temperature, in particular—influence the collective behavior of the molecules. The warmer the temperature, for example, the more energetic the random fluctuations. Thus low temperatures favor relatively ordered states (e.g., ice crystals), while high temperatures favor relatively disordered states (e.g., water vapor). Shifts between these states are typically abrupt. There is a critical temperature at which the system, when warmed, will suddenly undergo a phase transition from the ordered state to the disordered state, or vice versa in the case of cooling. One can explore phase transitions by representing the interactions between molecules in a computer model simulation, generating random molecular perturbations in the model to mimic the real-world random fluctuations of molecules.

I was using this type of Monte Carlo approach to investigate the theoretical behavior of liquid crystals—the materials used in liquid crystal displays (LCDs) employed in laptops, TVs, and digital watches. My research was aimed at determining how the critical temperature of the transition between the ordered and disordered phases of liquid crystals might vary under different conditions.¹⁴ My adviser was a theoretical physical chemist named Tony Haymet, who much later—coincidentally enough—went on to direct one of the world’s premier climate research institutions, the Scripps Institution for Oceanography at the University of California, San Diego.

When Tony left UC Berkeley a couple of years after my arrival, I continued my undergraduate research with Didier de Fontaine, a professor of materials science studying the properties of an exciting new material—a high-temperature superconductor. A superconductor is a material that conducts an electric current with no resistance, a property with profound real-world applications such as in the operation of super-fast bullet trains. Conventional (metallic) superconducting materials need to be cooled nearly to a temperature of absolute zero, making them expensive to maintain. In the mid-1980s, scientists discovered that certain ceramic materials had a remarkable property; they super-conducted at much higher temperatures, above even the temperature of liquid nitrogen (a very inexpensive coolant).

When I joined de Fontaine and his group in late 1987, they had been working for months to model the behavior of just such a material: yttrium barium copper oxide (YBCO...