If a single book has haunted the environmental movement, it’s The Population Bomb, by Stanford biologist Paul Ehrlich. Published in 1968 by Ballantine, the work is remembered for a handful of striking passages: its opening description of seething crowds in Delhi; its prediction that in the 1970s hundreds of millions of people would succumb to famine; its endorsement of policies, such as taxes on childbearing, that have, to say the least, gone out of style.

The sensationalism of the book’s argument was modest compared to its marketing. Gracing the cover of the paperback edition was an image of a bomb with a burning fuse and the tagline “Population Control or Race to Oblivion?” Another line added, “While you are reading these words four people will have died from starvation. Most of them children.” The book sold 2 million copies in two years. Ehrlich became a celebrity speaker and a frequent guest on popular television shows.

Ever since the famines failed to arrive on schedule, the book has been attacked with glee by conservatives and held to epitomize environmentalism’s folly. For their part, Ehrlich and his wife, Anne (who co-authored the book without attribution), stand by their conviction that population growth is wreaking horrific damage, and they take credit for raising awareness about the planet’s limited resources. They have a point: their book is, on the whole, more measured than its notorious bits and screaming cover would suggest. And the final chapter is titled “What If I’m Wrong?” Among environmentalists, the book has been not so much renounced as met with a sort of embarrassed silence—at least until recently. Environmental writer Alan Weisman, in his new book on population, Countdown, fervently defends the Ehrlichs, insisting that the Green Revolution merely bought us some time. Still, The Population Bomb is not counted as a classic along the lines of Rachel Carson’s Silent Spring. It surely didn’t help that Ehrlich later made and lost a high-profile bet with economist Julian Simon about the future price of commodities and generally remained a pugnacious public figure. By contrast, shortly after the publication of her book, Carson died.

The ambiguous legacy of The Population Bomb points to a larger issue: What’s the most compelling way to tell stories about threats to the environment? Does apocalyptic language ultimately do the environmentalist cause more harm than good, undermining the credibility of the warnings? Does it alienate readers by demanding that they think about an unbearable future? Or, by garnering more attention than mild-mannered writers, do doomsayers succeed in spurring essential conversation? Environmental writers face a host of choices: to invoke self-interest or moral responsibility; to elicit hope or sow fear and sorrow; to dwell on problems or solutions.

In A Climate of Crisis, a fascinating intellectual history of American environmentalism, Emory University historian Patrick Allitt discusses The Population Bomb and many other environmental texts. Though his account is fair-minded, it is book-ended by an argument that “the mood of crisis that surrounded a succession of environmental fears was usually disproportionate to the actual danger involved.” Our society, Allitt contends, has proved quite capable of addressing environmental problems. He highlights in particular the landmark legislation of the 1970s and the consequent, underappreciated “great cleaning” of America’s air and water; and he criticizes environmentalists for persisting in their rhetoric of doom rather than celebrating these triumphs. But Allitt’s very argument reveals another possibility: the progress he chronicles occurred not despite but in part because of the mood of crisis. Could major environmental legislation ever have passed without a pressing sense of urgency? If you warn loudly of potential disaster—whether regarding Y2K or air pollution—the price of success is to seem alarmist in retrospect. Allitt acknowledges that “the anticipation of catastrophe can often contribute to preventing it,” but he restricts that lesson to the case of nuclear weapons while downplaying the risks of climate change.

Writing about global warming and the associated ecological emergencies brings distinctive challenges. Different audiences disagree sharply on the facts. A recent survey conducted by the Yale Project on Climate Change Communication found that 23 percent of respondents believe that global warming is not happening. The project divided Americans into six groups with respect to climate change: the Alarmed (16 percent); the Concerned (27 percent); the Cautious (23 percent); the Disengaged (5 percent); the Doubtful (12 percent); and the Dismissive (15 percent). Rhetoric that will galvanize the Alarmed stands little chance of engaging the Disengaged or converting the Dismissive. Should writers choose an audience and tailor their work accordingly? How can language be exquisitely fine-tuned to prompt the desired response—to steer a course between despair and complacency?

Words alone will never halt a hurricane or stay the rising seas. But few would deny that the way we communicate about issues matters. Notwithstanding some encouraging developments, notably the Environmental Protection Agency’s new rules curbing emissions from coal-fired plants, it’s fair to say that climate-change polemicists have so far failed to achieve their goals. How might they promulgate their messages more effectively?

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In the standard environmentalist worldview, humans—and especially American consumers—are destroying the earth, which is equal parts deity and victim. This view is always going to antagonize a lot of people, who see it as preachy, misanthropic and joyless. Annalee Newitz, a science writer and proud member of Homo sapiens, takes a different approach. Her book Scatter, Adapt, and Remember is a primer for long-term human survival, spinning a sci-fi vision of the future. It downplays human culpability and the earth’s indispensability, espousing instead a can-do optimism oriented toward pragmatic problem-solving.

Newitz begins with an overview of our planet’s turbulent history, putting current realities and forecasts in context. Though our climate is changing and we are probably in the midst of a mass extinction—with scores of species vanishing daily—Newitz portrays these events as far from novel. She delivers a time-lapse narrative of planetary metamorphosis: continental plates smashing into each other, forming mountains and spilling carbon dioxide into the sea; blue-green algae emerging and beginning to release oxygen into the atmosphere; the climate lurching between “greenhouse” and “icehouse”; species dying out in massive numbers and then, slowly, new life repopulating the earth.

Newitz explains that a frequent culprit in mass extinction is climate change, and that minor shifts can trigger a cascade of effects that can quickly tumble into catastrophe. This pattern is at once alarming—it confirms the warnings of contemporary climate scientists about our own possible future—and somehow reassuring. It casts today’s strange weather as unexceptional in a natural, cyclical process. Newitz fully acknowledges the human role in the current warming and stresses the need to reduce greenhouse gas emissions. But her larger point is that if human societies hadn’t fouled the environment and altered the climate, some other force would—will—eventually threaten our survival anyway.

This fatalism is not bleak. On the contrary, there’s something liberating about the idea of ineluctable global catastrophe—to know that the asteroid will strike, the sun will explode, the supervolcano will erupt. Only when we think we can avert it—by driving less, installing solar panels, buying local, growing basil on the roof, attending protest marches, chaining ourselves to coal plants, getting arrested, inundating our elected representatives with phone calls—do stress and guilt set in.

“We have ample evidence that Earth is headed for disaster, and for the first time in history we have the ability to prevent that disaster from wiping us out,” Newitz writes. “Whether the disaster is caused by humans or by nature, it is inevitable. But our doom is not.” She explains that major asteroid strikes are expected to occur roughly every 100,000 years, which means “we are long overdue for another one.” She gives the impression not that we are destroying ourselves, but rather that we have gotten away with something. To Newitz, humans are exceptional not for the destruction we’ve caused—after all, climate change and mass extinction have numerous precedents—but for our unique ability to ultimately outfox the forces of global calamity.

Newitz proposes ideas to both mitigate human damage to the environment and prepare for the eventuality of catastrophe. Her suggestions range from the familiar green-agenda items (urban agriculture) to promising but unrealized techno-fixes (algae as an energy source and carbon suck) to more controversial proposals such as geo-engineering. She also advances some goals that are, depending on your perspective, either visionary or outlandish: building underground cities and colonizing other planets.

Newitz’s approach—her eschewal of dogma, her sunny confidence—might engage those who are put off by guilt trips and sermons. Indeed, a recent social science study found that raising the possibility of geo-engineering with conservatives seemed to “offset cultural polarization” and made the study’s subjects more concerned about climate change. (The advisability of geo-engineering is another question.) Not everyone, though, will share her enthusiasm for a future of riding space elevators and uploading our brains into computer software. “Don’t worry,” she concludes on her book’s final page. “As long as we keep exploring, humanity is going to survive.”

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For the first Earth Day, in 1970, the cartoonist Walt Kelly produced an iconic poster that declared, “We have met the enemy and he is us.” It’s a longstanding green sentiment, revived today by the New Yorker staff writer Elizabeth Kolbert. At the end of her book The Sixth Extinction, Kolbert quotes the upbeat send-off of Newitz’s book (identifying the source only in an endnote) and then offers a curt retort: “at the risk of sounding anti-human—some of my best friends are humans!—I will say that [human survival] is not, in the end, what’s most worth attending to.”

Newitz and Kolbert cover a striking amount of the same material, from the history of mass extinctions to the relationship of Homo sapiens with the Neanderthals. But for two advocates on the same fundamental side of the climate debate, their tones and values could hardly be more antithetical. Where Newitz praises humanity’s ability to scatter and adapt, Kolbert trains her focus on the countless victims of that enterprise.

Thoroughly researched and elegantly written, with the occasional touch of dry humor, The Sixth Extinction is an ambitious addition to Kolbert’s oeuvre. Her previous volume, Field Notes From a Catastrophe, published after serialization in The New Yorker, brought the perils of global warming to the attention of a large audience. In her new book, Kolbert tags along with scientists from all over the world and delivers dispatches on their findings. The news—whether about the fate of coral reefs, frogs or bats—is not good. She leaves no doubt about this, frequently ending sections with portentous quotes. “The extinction scenario,” one scientist tells her, “well, it starts to look apocalyptic.” At the end of another section, she quotes the journal Oceanography to the effect that if we continue along our current path, it is likely to lead to “one of the most notable, if not cataclysmic, events in the history of our planet.”

Both Kolbert and Newitz address the question of what makes our species special, and they more or less agree on the answer: the drive to explore and the ability to alter our surroundings. But rather than see this as cause for celebration or awe, Kolbert views it above all as a pox on our fellow earthlings. Her work epitomizes one classic subgenre of environmentalist writing: the catalog of human crimes against nature. In fact, compared with other members of this subgenre, such as Silent Spring and Bill McKibben’s The End of Nature, The Sixth Extinction is on the extreme end of pessimism, declining to prescribe or even exhort. The philosophical thrust is to debunk any romantic notion of an Edenic past in which noble savages frolicked peaceably among the flora and fauna. For example, Kolbert notes an ascendant theory that holds humans responsible for the extinction of megafauna such as mammoths millennia ago—an annihilation that led to a string of other ecological changes. “Though it might be nice to imagine there once was a time when man lived in harmony with nature,” she writes, “it’s not clear that he ever really did.”

To Kolbert, humankind is essentially destructive. “With the capacity to represent the world in signs and symbols comes the capacity to change it, which, as it happens, is also the capacity to destroy it,” she notes, continuing:

To argue that the current extinction event could be averted if people just cared more and were willing to make more sacrifices is not wrong, exactly; still, it misses the point. It doesn’t much matter whether people care or don’t care. What matters is that people change the world…. If you want to think about why humans are so dangerous to other species, you can picture a poacher in Africa carrying an AK-47 or a logger in the Amazon gripping an ax, or, better still, you can picture yourself, holding a book on your lap.

With this last phrase, Kolbert implicates both the reader and herself and reveals the tension at the heart of her work. She is devoted to documenting environmental devastation, clearly convinced that this effort has value; but her inquiry has led her to the conclusion that even her own project—which, after all, involved plane travel and tree pulp—is part of the problem.

All of this is true, as far as it goes. But as rhetoric, it has its limitations: this very fatalism, in a sense, lets humans off too easily. If we are destined to destroy as the dark side of our creativity, why bother trying to avert catastrophe? If we are an innately destructive force, trying to save the planet from ourselves is more pointless than trying to intercept an asteroid.

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Longtime environmental writer and activist Bill McKibben is likely sympathetic to aspects of Kolbert’s worldview. Her despondency about human violence to the planet resonates with much of his work. But McKibben has recently hit upon a new way of framing the issue of climate change: demonizing a subset of bad guys—that is, identifying a “them.” In a 2012 Rolling Stone article called “Global Warming’s Terrifying New Math,” McKibben wrote that the fossil-fuel industry is planning to extract and burn more than five times as much carbon as the scientific consensus deems safe. “We have met the enemy and they is Shell,” he wrote, in a significant twist on that famous quote. (He presumably knows the original context of the quote, though his readers may not.) In his next move, he would target the enemy not just in word but deed: a campaign, centered on college campuses, to divest from fossil-fuel companies, modeled on the campaign to divest from apartheid South Africa in the 1970s and 1980s. In a pivotal victory for the young movement, Stanford University announced plans in May to divest from coal companies.

McKibben chronicles the development of this strategy in his book Oil and Honey. As he tells it, his current role is “unlikely” because at heart he is a writer, happiest in his beloved Vermont, alternating between his desk and the woods. But his overwhelmingly keen awareness of the climate emergency has, he writes, forced him to become the reluctant leader of a nascent movement—constantly on the road, giving speeches, sitting on panels with members of Congress. It’s too soon to say whether he will achieve his goals, but he deserves credit for helping to create a new, adversarial dynamic. If the enemy is us, only a small minority of people will ever join the fight.

What does it mean for McKibben to transform himself from a writer into an activist? As a dichotomy, it’s somewhat misleading: McKibben’s writing has always had an activist bent, and his current activism involves a great deal of writing, including this new book. As he recalls here of his first book, The End of Nature, “my initial theory (I was still in my twenties) was that people would read the book—and then change.” But as that theory proved increasingly untenable, he was compelled to think hard and long about how words, in conjunction with actions, could produce the impact he sought.

His writing often falls these days into the genre of the exhortatory tweet (“Half a million emails is a lot. I don’t know if we can do it. But we’re sure as hell going to try”). He also exhorts himself (“Back to work. On message”) or engages, to his chagrin, in some calculated posturing with political types: “they say something, we say something back, they push, we push…. It ran counter to every instinct of a writer, which is simply to say what’s true.” He is constantly communicating with a variety of constituencies, with specific intentions: to persuade, inspire or bluff, depending on his interlocutor. On one of his whirlwind tours, he spends an afternoon with the poet Gary Snyder and writes, “For an afternoon—and it was the greatest present he could possibly have given me—I felt like a writer again, the thing I most wanted to be and at least for the moment really couldn’t.”

In this conception, being a writer means dwelling on the sounds and textures of words, not on their utility; meandering in the eternal, not obsessing over the latest news cycle in Washington; savoring complexity, not dividing the world into good and evil. It means the primacy of curiosity, of irreverence; really, it means allegiance to no cause. McKibben, as an activist, needs to privilege the instrumental over the poetic, rhetoric over subtlety. He aches for his old, less strictly activist role, but he is drawn to make this sacrifice—and one of the instrumental purposes of this book is to inspire its readers to make sacrifices of their own.

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Curiosity, subtlety, nuance—these are casualties of the polarized debate about climate change. The acknowledgment of uncertainty becomes ammunition for the so-called climate skeptics. But Craig Childs, although deeply concerned about anthropogenic climate change, is refreshingly indifferent to eco-etiquette. His book Apocalyptic Planet has an ingenious premise, just shy of being a gimmick: he visits a series of extreme climate locations, each of which represents a possible future for our planet, depending on how climate change and other forces evolve. He begins in the Mexican desert mid-drought, then ventures to the melting glaciers of Patagonia, the monoculture of an Iowa cornfield and so on. His ominous, lyrical chapter titles follow a pattern: “Deserts Consume,” “Ice Collapses,” “Mountains Move,” “Seas Boil.”

Childs is arguably the Ryszard Kapuscinski of environmental writing, with his daredevil adventures taking him to Arctic glaciers and treacherous rapids. He intersperses his personal narrative with history and reporting, and some of his observations might make an activist like McKibben bristle. He quotes Konrad Steffen, a prominent climate scientist with whom he travels to Greenland: “If we’ve done anything, we’ve stopped the next glacial period from happening by warming the earth.” He reports, “We do not live in a particularly impressive period in history for watching sea levels rise.” These statements may be valid, but they are not “on message.” He also gives space to foils, such as his friend Angus, a former Jehovah’s Witness who accompanies him through the “biotic dearth” of an Iowa cornfield and muses that perhaps the earth needs periodic mass extinctions to rest. (Childs takes this notion seriously and presents it to E.O. Wilson, who dismisses it.)

Above all, what sets him apart from other environmental writers is his curiosity. More than dread or hope, he seems to have a burning eagerness simply to find out what might happen: “I wondered if I could trade my own decades for a two-hundred-year life span just to see what page turns next for the earth.” He craves intimate sensory experience of our “twitching, restive planet,” submitting to dry desert heat, walking on barely dried lava, touching glaciers and hearing the explosive sounds of their collapse.

His descriptions of these experiences are evocative. In the desert: “I had sand in every part of me. My molars wouldn’t touch.” On watching melting ice: “Each teardrop shimmered for a moment and vibrated tenuously, then fell. This is how climate works, I thought. Forces push and pull, weather begins to switch back and forth, summer and winter turned upside down, and then the system jumps. The drip falls.”

His humans are neither villains nor heroes. They play a relatively minor role in his account, as do other species. It’s the earth that looms largest in Childs’s consciousness, more agent than victim. As he realized after living through an earthquake, “Humans may have a big hand in carpeting the atmosphere with heat-trapping gases and dumping every toxin we can imagine into waterways, but when the earth decides to roll, it is no longer our game.” He writes about the planet we inhabit with awestruck deference. Even while lamenting our losses, he wants to take them in up close. As Childs asks in this passage about his trip to Patagonia: “Saving the world? You can always hope. But to be alive in the last geologic moments of ice, wouldn’t you come and put your hands against it?”

Perhaps all environmental writers lie on some continuum from activist to author, their books somewhere between pamphlets and poems. They dream of saving the world; they know that the likeliest outcome is failure. But they write anyway—to bear witness, to make sense of what is happening, to say what’s true.

Back in Patagonia, Childs writes this of the last moments of ice: “As it tinkled and cracked in the sun, I snapped off a tab and crunched it in my mouth. It turned to water instantly, as if it had been waiting a hundred centuries for this moment.”