When it comes to key warriors in America’s battle over the causes of climate change, few rival Pennsylvania State University professor Michael E. Mann. Mann, who directs the Penn State Earth System Science Center, led a 1998 reconstruction of temperature records going back thousands of years and showing that global averages had shot up in recent decades.

Featured in a 2001 report by the U.N. Intergovernmental Panel on Climate Change, the chart resembled a hockey stick, with the ancient temperatures running along the handle and the latest figures rising sharply at the base. It sparked intense debate over the human contribution to global warming and transformed Mann from a geeky geophysicist into a public fighter in a bruising political and legal war over how to conduct science and public policy.

Much of the industrial and developing world accepts the scientific consensus that the burning of fossil fuels, and other activities that release heat-trapping greenhouse gases, contribute to climate change; on Friday, the International Energy Agency announced that global carbon dioxide emissions from fossil fuel burning had reached a record high of 31.6 gigatons in 2011, up 3.2 percent from 2010. A March survey by Gallup shows that 53 percent of Americans attribute global warming to human activity. But in the past three years, some Americans have challenged this view, particularly conservative Republicans, and the political elite is sharply divided.

Some advocates have gone so far as to hack computers and steal the e-mails of Mann and other climate researchers in an effort to undermine global climate negotiations. A respected hydrologist retaliated by tricking a climate-skeptic group into releasing its internal documents.

Mann’s new book, “The Hockey Stick and the Climate Wars,” is part of a series of attempts by activists and others to answer the question of why global warming has become a political flash point. Mann has devised an analogy to explain why he and other researchers have become the objects of such fierce public scrutiny and vilification, which he terms “the Serengeti strategy.” Likening climate scientists to zebras, he writes, “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.” He asserts that he and others have become targets because their findings challenge the entrenched fossil-fuel industries, which have tried to discredit them.

"The Hockey Stick and the Climate Wars: Dispatches from the Front Lines" by Michael E. Mann (Columbia University Press/Columbia University Press)

There is no question that Mann has found himself in the crosshairs of those who promote the idea that global warming stems from nonhuman factors, such as sun spots and natural temperature variability. The hockey stick relied on proxy data derived from a range of sources — including tree rings, cores extracted from ice sheets, corals and lake sediments — to reconstruct temperatures from hundreds of years ago, times for which there is no written record. Mann and his team used a statistical tool called “principal component analysis” to tease out which factors are most responsible for a given change over time and to compare data from all over the globe.

Two Canadians, mining consultant Stephen McIntyre and economist Ross McKitrick, challenged the hockey stick on a variety of fronts. First they went after the proxy data; later they employed the same statistical tool that Mann and his colleagues did, but in what Mann considers an inconsistent way. The result was a smoothing out of the pattern embodied in the hockey stick. “If there is a lesson” in these sorts of fights, Mann writes, “it is that scientific findings that rest on such technical complexities are prone to abuse by those with a potential ax to grind.”

Herein lies the problem with the current climate debate: It’s an insider’s game. The average American doesn’t study principal component analysis and doesn’t need to. But when that’s what scientific experts — and lawmakers who have been briefed by their staffers — are talking about, it leaves most of the public in the dark. Mann makes this point several times, as when, for example, he describes Rep. Henry Waxman (D-Calif.) throwing around arcane scientific terms to challenge climate skeptics during a 2005 hearing: “I’m fairly certain that this was the first congressional hearing at which a representative uttered the phrase ‘regularized expectation-maximization.’ You could just hear statistics junkies everywhere doing their best Beavis and Butthead impressions: ‘Did he just say regularized expectation-maximization? Heh, heh, heh.’ ”

The strength of Mann’s book lies in the light he sheds on how the scientific peer-review process works, along with his first-hand account of his role in the national political feud. Mann began working on his PhD with the assumption “that natural variability might be more important than some scientists thought,” and he takes the reader through his professional and personal conversion to a climate activist. Rather than confining his work to academia, he now battles his opponents on the Web, on talk shows and in print.

Mann dwells at length on editorial improprieties involved in the publication of a 2003 paper by Willie Soon and Sally Baliunas that challenged the notion that the past century was the warmest in 1,000 years. “The importance of the integrity of the editorial and peer review process cannot be overstated,” he writes. “While it is not infallible and bad papers inevitably get published occasionally, the process is an essential component of the self-correcting machinery of science.”

Mann’s writing style feels strained at times — at one point, when debunking skeptics’ claims, he writes, “In the climate change denial playbook, facts must never get in the way of a good smear opportunity” — but he manages to convey the disorienting sensation of a scientist suddenly coming under fire. Over the past decade he has had to answer questions from then-House Energy and Commerce Committee Chairman Joe Barton (R-Tex.) about every grant he ever received; had his e-mail correspondence posted on the Internet, in an incident that became known as Climategate; faced a lawsuit in which Virginia Attorney General Ken Cuccinelli unsuccessfully sought access to Mann’s correspondence while he taught at the University of Virginia; and found himself the subject of a mocking YouTube video.

(For those seeking a climate skeptic’s take on global warming, the Heartland Institute has recently released a book by sociologist Rael Jean Isaac, “Roosters of the Apocalypse,” which declares that its side has won the public opinion and policy battle on climate change — and also attacks Mann.)

This experience — as well as his climate work — has turned Mann from a naive academic who dressed in his best suit for a 2003 Senate hearing into an outspoken advocate for cuts in greenhouse gas emissions. Perhaps that’s why he overlooks ethical lapses by some scientists who share his views. Describing how a British colleague urged Mann and others to delete e-mails they wrote each other about the basis for their scientific findings, to prevent them from becoming public, Mann calls that advice “ill-advised.” And he details with pride how an increasing number of researchers have joined in the debate: “My fellow scientists will be fighting back, and I look forward to joining them in this battle.”

One of those fighting back is James Lawrence Powell, a geochemist and former president of Reed College and Franklin and Marshall College, who has detailed every possible misdeed he can identify within the climate-skeptic community in “The Inquisition of Climate Science.” Resting largely on research done by others, this highly polemical book is clearly aimed at the converted, rather than anyone who might be on the fence.

As climate researchers, their allies and their opponents debate the science in the blogosphere, lecture halls and other forums, how good a job has the media done in reporting on the conflict? That is the question University of Colorado at Boulder professor Maxwell T. Boykoff addresses in his book “Who Speaks for the Climate?” Although he provides a thoughtful analysis of British and American climate coverage over the past quarter-century, he uses too much academic jargon and too many references to French philosopher Michel Foucault to appeal to the general public.

Boykoff suggests that many mainstream reporters quote climate contrarians out of a misguided quest for journalistic balance. (Full disclosure: Some of my stories were included in his statistical analysis, though he doesn’t explicitly critique them.) But this point misses the real reason that many journalists include comments from climate skeptics: They are trying to capture the political divide over global warming.

Yet Boykoff provides a helpful overview of how reporting on global warming has evolved as the scientific consensus has solidified, and why informed coverage matters. As he writes, “A more informed public and more wisely supported links between science, policy and media are in our collective self-interest.” He also helps explain why the climate-change debates are so intense. “They cut to the heart of how we live, work, play and relax in modern life, and thus critically shape our everyday lives, lifestyles and livelihoods.”

Non-experts who want a concrete sense of climate change’s impact — and a lyrical reading experience — should turn to “A Great Aridness,” by William deBuys. A natural storyteller who has spent most of his adult life in the Southwest, deBuys follows the trails of climate change’s effects. Those trails “lead to the sidewalk-and-gutter, two-car subdivisions of Las Vegas and to the raw cinderblock and shipping-crate colonias of Ciudad Juarez,” he writes. “They will lead to backcountry wilderness as well as ordinary backyards, to mile-deep canyons and to canals hundreds of miles long.”

By reading books like deBuys’s, Americans might begin to envision an end to the climate wars. In chronicling changing weather patterns and their effects on Southwestern history, he suggests that shifts might come in fits and starts, rather than in the straight line some might be looking for. But the shift is happening. “It seems that when the climate changed, it did not change in just one way,” he writes. “Perhaps it never does.”


Juliet Eilperin is the national environmental reporter for The Washington Post and the author of “Demon Fish: Travels Through the Hidden World of Sharks,” to be published in paperback in July.


Dispatches From the Front Lines

By Michael E. Mann

Columbia Univ. 395 pp. $28.95


By James Lawrence Powell

Columbia Univ. 232 pp. $27.95


Making Sense of Media Reporting
on Climate Change

By Maxwell T. Boykoff

Cambridge Univ. 228 pp. Paperback, $29.99


Climate Change and the Future
of the American Southwest

By William deBuys

Oxford Univ. 369 pp. $27.95