“For a geophysicist, what’s going on is stunning,” my friend told me. “We used to believe these systems needed thousands of years to make these shifts. Instead it’s happening so fast that it’s terrifying. Conceivably, you could start seeing truly bad effects in a hundred years.”
And this is one of the great difficulties in thinking about climate change: what seems terrifyingly fast on the geological scale is unfathomably long on the human scale. By “truly bad effects” DeConto meant flooded coasts, vanished islands, awful droughts, and, maybe, storms of unprecedented power. But even if these occur in the time he fears—even if they transpire in the geologically insignificant span of a century—they will not be seen by him or me. Quite possibly every person who reads this book will be dead before they occur, as will most of their children. How many governments make plans for such long-term contingencies? How many families do?
The most likely victims of climate change, in the short run, are people who live on oceanic islands, in very low-lying coastal settlements, in ice-bound Arctic communities, and around forests that burn after unwonted dry spells. Millions of people live in these places, but they are a small fraction of the world’s billions. The greatest potential harms of climate change will be experienced by future generations—centuries in the future, or even millennia. By our actions today (burning fossil fuels), the argument is, we are dumping problems (drought, sea-level rise) on tomorrow.
On the one hand, forcing other people to clean up our mess violates basic notions of fairness. On the other hand, actually preventing climate-change problems would require societies today to make investments, some of them costly, to benefit people in the faraway future. It’s like asking teenagers to save for their grandchildren’s retirement. Or, maybe, for somebody else’s grandchildren. Not many would do it.
Would they be wrong? How much concern should we have for future generations? The harder one looks at the problem, the more confusing it seems. “The problems of climate change,” says the New York University philosopher Dale Jamieson, “swamp the machinery of morality.” (“A perfect moral storm,” says Stephen M. Gardiner, another philosopher.) The basis for arguing for action on climate change is the belief that we have a moral responsibility to people in the future. But this is asking one group of people to make wrenching changes to help a completely different set of people to whom they have no tangible connection. Indeed, this other set of people doesn’t exist. When one tries to make plans for nonexistent people, the result is an intellectual quagmire, because there is no way to know what those hypothetical future people will want.
Today we live in a world where almost everywhere slavery is illegal, women can vote and own property, and overt obeisance to social class is frowned upon. Most decision-makers who lived three hundred years ago would have regarded these developments with horror. Had they grasped that the future could be like this, they would have sought to prevent it.
Picture Manhattan Island in the seventeenth century. Suppose its original inhabitants, the Lenape, could determine its fate, in perfect awareness of future outcomes. In this fanciful situation, the Lenape know that Manhattan could end up hosting some of the world’s great storehouses of culture—the Metropolitan Museum of Art, the American Museum of Natural History, the Museum of Modern Art, the New York Public Library, the opera and symphony at Lincoln Center. All will give pleasure and instruction to countless people. But the Lenape also know that creating this cultural mecca will involve destroying a diverse and fecund ecosystem. I suspect the Lenape would have kept their rich, beautiful homeland. If so, would they have wronged the present?
Economists tend to scoff at these conundrums. Forget all of this philosophical foofaraw about the rights of hypothetical people, they say. That’s just a smokescreen for “paternalistic” intellectuals and social engineers “imposing their own value judgments on the rest of the world.” (I am quoting the Harvard economist Martin Weitzman.) Instead, economists suggest, one should observe what people actually do—and respect that. In their daily lives people care most about the next few years and don’t take the distant future into much consideration—they prefer “present over future utility,” in the economist’s phrase.
In technical terms, this idea is expressed with the discount rate, which is like the antimatter version of an interest rate. Imagine that today I would pay $200,000 for a new house. How much would I pay today if I had to wait five years to receive the house? $100,000? $50,000? Today and tomorrow, the house is the same physical object. But as a rule people won’t pay as much for a house they have to wait for as a house they can occupy immediately, and the longer they have to wait, the less they are willing to pay. Usually economists use 5 percent as a discount rate—for every year of waiting, the price goes down 5 percent, compounded. Doing the arithmetic, a 5 percent discount rate means that goods and services are worth roughly half as much to me in fifteen years as they are today.
The implications for climate change are both striking and, to many people, absurd. At a 5 percent discount rate, the Argentine-American economist Graciela Chichilnisky has calculated, “the present value of the earth’s aggregate output discounted 200 years from now is a few hundred thousand dollars.” In econospeak, “the earth’s aggregate output” means “the human race and all its works.” To prevent our species from being wiped out in two centuries, Chichilnisky points out, standard economics suggests that the world would pay “no more than one is willing to invest in an apartment.”
Intuitively, I am hard-pressed to believe that most people would endorse the notion that the future of humankind is worth no more than a single apartment. Chichilnisky, a major figure in the IPCC, has argued that this kind of thinking about discount rates is not only ridiculous but immoral; it exalts a “dictatorship of the present” over the future. Economists could retort that people say they value the future, but don’t act like it, even when the future is their own. And it is demonstrably true that many—perhaps most—men and women don’t set aside for retirement, buy enough insurance, prepare their wills, or a hundred other precautions, even if they have sufficient resources. If people won’t make long-term provisions for their own lives, why should we expect people to bother about climate change for strangers many decades from now?
Not so fast, says Samuel Scheffler, a New York University philosopher who is the author of Death and the Afterlife (2013). The way people feel and act about their individual futures is not the same as how they feel and act about our species’s collective future. In his book, Scheffler discusses another book: Children of Men, a best-selling 1992 science fiction novel by P. D. James that was adapted into a movie by the filmmaker Alfonso Cuarón. The premise of both book and film is that humanity has suddenly become infertile, and our species is stumbling toward extinction. In this scenario, as Scheffler notes, nobody alive is worse off, at least in the short run. Couples are denied future children, but they lose no children they already have; nobody even loses money. The present doesn’t change materially. All that is lost is a future that we would never have seen.
Both book and movie show this world as one of anomie and despair. Because our species has lost its future, life seems meaningless. Civilization wanes; aimless, violent gangs roam ruined streets. The belief that human life will continue, even if we ourselves die, is one of the underpinnings of society.
Logically speaking, the desolation in Children of Men is peculiar. As Scheffler points out, all people have known from childhood that they will die. As individuals, we have no long-term future. Personal extinction is guaranteed. But this tragedy—one that will be directly experienced by every single man, woman, and child—provokes no public alarm. No tabloid has ever blared the headline, “All 7.3 Billion of Us to Vanish Within Decades.” Our conviction that life is worth living is “more threatened by the prospect of humanity’s disappearance than by the prospect of our own deaths,” Scheffler writes in Death and the Afterlife.
The idea is startling: the existence of hypothetical future gen
erations matters more to people than their own continued existence—“evidence of hitherto unsuspected reserves of altruism,” as Scheffler drily comments.
What this suggests is that, contrary to economists, the discount rate accounts for only part of our relationship to the future. People are concerned about future generations. Even if the logic is hard to parse, they think that humanity’s fate is worth more than an apartment. But trying to transform this general wish into specific deeds and plans is confounding.
Imagine a ladder of moral concern that begins with an exclusive concern for oneself and extends through concern for family to concern for culture or religion to concern for all cultures and religions and beyond that to future generations. At the far end is the Margulis position, a concern for a natural order that is so all-encompassing that it is hard to distinguish from unconcern. It is a philosophical truism that exclusively caring about oneself is not a route to a happy or satisfying life. Another philosophical truism is that a lofty concern for all of existence is the province of saints, and sainthood is not required for ordinary people to live decently and well.
In the middle, where most people spend their days, it is hard to distinguish morally between positions. It is easy to disparage people who think only of their family or neighborhood. But higher up the ladder is not necessarily better—think of the numberless instances where people, genuinely believing that they are acting for the benefit of larger entities, have ended up doing awful things. Would the world have been better off if the soldiers in the Crusades had not tried to spread the light of Christianity and instead had stayed home and improved their own villages? Or, again, consider Manhattan Island. If the level of concern is for preserving all cultures, it might make sense to bulldoze all the buildings and return the land to the Lenape. After all, there are many wonderful centers of Western culture; there is only one Lenape homeland. But removing the millions who live in Manhattan could not be done without creating terrible hardship and dislocation on the level of the community, quarter, family, and individual.
In addition, reaching for higher levels on the ladder of concern is more complex and difficult. If nothing else, the many misadventures of foreign aid have shown how difficult it is for even the best-intentioned people from one culture to know how to help other cultures. Now add in all the conundrums of working to benefit people in the future, so inherently unknowable, and the hurdles grow higher. Thinking of all the necessary actions across the world, decade upon decade—it freezes thought. All of which indicates that although people are motivated to reach for the upper rungs, they are more likely to succeed in their aspirations if they stay rooted to the lower, more local ones.
Margulis, I suspect, would have put this in biological terms. Evolution has provided the human brain with marvelous tools for detecting and resolving fast-moving, clearly visible, small-scale, near-future risks. By the same token, the brain is easily overwhelmed by slow, abstract, large, long-term problems. Patiently dribbling money, year by year, into a retirement account, calculating the insurance needed to compensate for an unlikely but real hazard, contemplating the arrangement of one’s death—they boggle the mind. (Most people’s minds, anyway.) Climate change is all of these and more: gradual, impalpable, world-altering, multigenerational, a situation that will not become readily tangible until irreversible lines already have been crossed. “It is not the sort of problem that Mother Nature raised us to solve or even notice,” Jamieson, the philosopher, has written.
None of these considerations seem to have occurred to the early researchers on climate change. But they help to explain the reactions to their work later on.
“There Will Be Megadeaths”
The small band of climate researchers was riveted by the discovery—reported, however confusingly, by Revelle and Suess—that human-released carbon dioxide could affect the climate. Figuring out exactly what would happen, though, turned out to be vexingly difficult, because climate was a morass of feedback mechanisms.*7 If higher carbon dioxide levels made the atmosphere grow warmer, for example, it would become more humid. On the one hand, moister air would absorb more heat, further driving up temperatures: a positive feedback loop. On the other hand, moister air would lead to more cloud cover, which would block the sun, lowering temperatures to what they were before: a negative feedback loop. Similarly, higher temperatures could melt the ice in glaciers and at the poles, leaving bare rock. Because the rock is darker than the ice, it would soak up more of the sun’s heat, raising the temperature and melting more ice to expose more rock: positive feedback. But the cold meltwater from the glaciers would pour into the oceans, lowering their temperature, which would chill the air over the water: negative feedback. The permutations were endless, and adding them up was stunningly difficult.
Worse, the tangle of interacting feedback loops meant that climate was subject to the “butterfly effect.” The term refers to a now-famous metaphor for how tiny changes in complex systems can have wildly disproportionate effects. It originated in 1972, when the MIT meteorologist Edward Lorenz asked a conference, “Does the flap of a butterfly’s wings in Brazil set off a tornado in Texas?” His answer: Well, yes, actually—maybe.
By the time Lorenz asked about butterflies, he had been creating computer models of weather and climate for two decades. His biggest breakthrough had come while tinkering with a weather model in 1961. It consisted of twelve equations that expressed relationships between variables like temperature, humidity, barometric pressure, and wind speed. Although the model was of toy-like simplicity, Lorenz’s computer—a clunky mass of vacuum tubes programmed with punch cards—printed out results that looked surprisingly like actual weather, with storm fronts shifting, winds blowing, and temperatures rising and falling. At one point Lorenz decided to check a calculation by repeating it. The machine made computations out to six decimal places, but for the sake of simplicity Lorenz wrote only the first three—he abbreviated, say, 0.111111 to 0.111. He fed the truncated numbers into the machine and was startled to obtain a totally different answer than the first time. The two computer runs were similar at the beginning, but then the output lines drew apart until they looked completely different. A tiny difference in initial conditions had dramatically changed the outcome.
Lorenz was baffled. Cutting off a few decimal places was a trivial change; it shouldn’t have a big effect. It was as if he had repeated a three-day automobile test drive but changed the initial speed from 100 miles per hour to 100.1 miles per hour—and ended up completing the trip in twice the time on a different route. Surely he was seeing some glitch in the computer.
After a year of digging, Lorenz realized that the computer was right and his intuition had been wrong. He proved that the type of equations one would use in a model of daily weather—equations that described convections or flows of various types—were unavoidably sensitive to small initial changes. And the sensitivity applied not only to weather, but to climate as well. (Weather and climate are not the same. Weather is the daily local ups-and-downs, climate the overall atmospheric system.) People had known for centuries that entire decades could be much drier or wetter than their predecessors. But they had believed that these changes were the result of predictable, regularly occurring cycles—the increase and decrease of sunspots, perhaps, or the oscillation of ocean currents. Instead, Lorenz was saying, climate was more like a random walk, an unstable trajectory driven by trivial variations. Indeed, Lorenz couldn’t “prove that there existed a ‘climate’ at all, in the traditional sense of a stable, long-term statistical average.” The quotation comes from the historian Spencer R. Weart’s 2008 book, The Discovery of Global Warming. At the time, Weart explained, the task of climate scientists
was to compile statistics on past weather, in order to advise farmers what crops to grow or tell engineers how great a flood was likely over the lifetime of a bridge….Yet the value of this kind of climatology to society was based on the conviction that statistics of the previous half century or so could reliably des
cribe conditions for many decades ahead. Textbooks started out by describing the term climate as a set of weather data averaged over temporary ups and downs—it was stable by definition.
Now Lorenz had challenged the most basic idea in the discipline.
Climate scientists encountered Lorenz’s ideas in 1965, when he gave the keynote address at a conference in Colorado called “The Causes of Climate Change,” the first big scientific gathering devoted to the subject. As he described the instability he had uncovered, his audience made the connection with carbon dioxide. Conference organizer Roger Revelle, who had been skeptical, was persuaded. If small changes in initial conditions could have enormous long-term effects, he said in a summary speech, then perhaps tiny rises and falls in atmospheric carbon dioxide could “ ‘flip’ the atmospheric circulation from one state to another.” Arrhenius and Callendar had been vindicated. A scientific consensus was emerging: a tiny shift in the atmosphere’s carbon dioxide load could make Earth hard to live on. And Keeling had shown that carbon dioxide levels were rising in exactly the way that might lift temperatures to new heights. Revelle was then on a panel charged by the U.S. president with writing a report about environmental pollution. He took advantage of the position to create a subpanel on carbon dioxide and write the first-ever official government report about the possibility of climate change.
That didn’t end the matter. Few people care about rising temperatures per se. What matters, as Revelle, Suess, Keeling, and their colleagues realized, is their potential future influence on other things: agricultural productivity, sea levels, rainfall patterns, ocean chemistry, infectious disease. And nobody truly knew what these might be. Climate scientists had already engaged in some of the most elaborate calculations ever performed just to understand basic atmospheric physics. Now they would have to add agronomy, oceanography, disease ecology, and a host of other fields—a monumental task.