If Vogt was dismayed by the thought of competing with the wealthier, more socially prominent Osborn, he never showed it. Letters volleyed back and forth between them, Osborn writing from the plush Fifth Avenue headquarters of the Zoological Society, Vogt from hotels in Latin America or his government-issue office at the Pan American Union. Osborn credited Vogt and Leopold for giving him the correct “philosophical approach to the problem.” Vogt told Osborn that his manuscript had kept him up “until I finished it about 2:00 a.m.” And he paid the author a writerly compliment: “More than once, as I went through your text, I said to myself, ‘I wish I had thought of that.’ ” The two books came out within months of each other in 1948, Osborn’s Our Plundered Planet on March 25, Vogt’s Road to Survival on August 5.
Both were enormously successful. Our Plundered Planet was reprinted eight times and translated into thirteen languages. Road to Survival was a main selection of the Book-of-the-Month Club (a nationwide subscription service that automatically sent books deemed worthy to 800,000 American subscribers) and Reader’s Digest (the biggest-circulation magazine in the world, which published a condensed version of the book for its 15 million worldwide subscribers). Road was translated into nine languages. Vogt was given awards by the Cranbrook Institute of Science and the Izaak Walton League, and the book was adopted within weeks by twenty-six colleges and universities as a textbook (many more would do so later).
The early reviews for both books were overwhelmingly positive. Our Plundered Planet, reported the San Francisco Chronicle, was “the most important word of warning delivered to the human race in the present century.” Vogt’s book was “controversial, exciting, dismaying and yet hopeful,” said The Boston Globe. To Saturday Review, Road was “the most eloquent, provocative and informative book that has been written thus far in the United States on conservation—or the lack of it.” The Washington Post was particularly enthusiastic:
Within the lifetime of many living men, there will not be enough to eat anywhere on the planet….We are living on borrowed time, or more accurately on rapidly dwindling capital….This is easily the most important book of 1948. It is also one of the best written.
Probably most important to Vogt were the personal congratulations. Roger Tory Peterson, a bird man through and through, had been skeptical about Vogt’s decision to paint on a broader canvas. Road, Peterson now said, was the culmination of everything Vogt had been working toward. Speaking for her husband, Robert Cushman Murphy’s wife, Grace, wrote, “Your book is the new Bible.” Early on, Aldo Leopold had praised Vogt’s proposed book outline as “excellent.” Now he told Vogt that Road was “the most lucid analysis of human ecology and land use that I have yet encountered.”
As Vogt’s message sunk in, though, he was denounced. “Real scientists take a dim view of Road to Survival,” scoffed Time, the world’s best-selling newsmagazine. Every aspect of Vogt’s “creed,” wrote its anonymous reviewer, “is either false or distorted or unprovable.” Road was condemned by Roman Catholics, because it advocated birth control; by conservatives, because it supported state regulation; and by business interests, because it attacked capitalism (the Reader’s Digest condensation excised Vogt’s critiques of the free market). But the greatest ire came from the left. Denouncing the book as a “totally unaware,” “incoherent,” “screaming” “bill of goods,” The Nation magazine called Vogt’s ecology proof of “science’s bankruptcy in the face of pressing modern problems.” At a world Communist summit in Paris, a Soviet novelist drew cheers when he damned Road as “merely a gross means of corrupting the American people.” Our Plundered Planet was equally bad. Reading Vogt and Osborn, the novelist insisted, had caused “a serious increase in their crime wave.”
Unsurprisingly, the two books were in some ways quite similar—and not just in that both railed against a new chemical called DDT. They were jointly inventing a new literary genre: the concerned report on the global condition. They were the first to portray our ecological worries as a single Earth-sized problem for which the human species is to blame. And by stating that the problem is one interconnected, worldwide issue, rather than something local or national, they implicitly argued that ecological issues could only be solved by a unified global effort, administered by global experts—by people, that is, like Vogt and Osborn.
Vogt and Osborn were also the first to bring to a wide public a belief that would become a foundation of environmental thought: consumption driven by capitalism and rising human numbers is the ultimate cause of most of the world’s ecological problems, and only dramatic reductions in human fertility and economic activity will prevent a worldwide calamity.
Of the two, Road had greater impact. In a way its author could not have imagined, it became the blueprint for today’s environmental movement. The book inspired both Rachel Carson, who later wrote Silent Spring, and Paul Ehrlich, author of The Population Bomb—the two most important environmental books of the 1950s and 1960s. “Every argument, every concept, every recommendation made in Road to Survival would become integral to the conventional wisdom of the post-Hiroshima generation of educated Americans,” the historian Allan Chase has written. Vogt’s ideas “would for decades to come be repeated, and restated, and incorporated again and again into streams of books, articles, television commentaries, speeches, propaganda tracts, posters, and even lapel buttons.”
Part of the impact was due to Vogt’s arrestingly harsh tone. Both Osborn and he lamented “the American way of doing business,” which had ruined land (they said) since the time of the Pilgrims. But only Vogt described all of U.S. history as little more than a “march of destruction,” in which colonists “chopped, burned, drained, plowed, and shot” their way from the Atlantic to the Pacific. “Our forefathers,” he thundered, were “one of the most destructive groups of human beings that have ever raped the earth. They moved into one of the richest treasure houses ever opened to man, and in a few decades turned millions of acres of it into a shambles.” Unlike Osborn, a product of Wall Street, Vogt scorned capitalism. He imagined his critics wailing,
“Free enterprise has made our country what it is!” To this an ecologist might sardonically assent, “Exactly.” For free enterprise must bear a large share of the responsibility for devastated forests, vanishing wildlife, crippled ranges, a gullied continent, and roaring flood crests. Free enterprise—divorced from biophysical understanding and social responsibility.
Ecological collapse tomorrow would lead the day after to nuclear war. If humankind kept ignoring ecological realities, he warned,
there is little probability that mankind can long escape the searing downpour of war’s death from the skies. And when this comes, in the judgement of some of the best informed authorities, it is probable that at least three-quarters of the human race will be wiped out.
Road laid out the basic tenets for a now-common way of thought: environmentalism. Environmentalism is more than the simple recognition that polluting a neighbor’s well or destroying a bald eagle’s nest is a bad idea. In most cases that recognition can be viewed as a function of property rights. By poisoning a well, a polluter is, in effect, seizing the water without its owner’s permission. (More precisely, it is seizing use of the water.) The eagles, too, are being taken from their owner, the public. Environmentalism, by contrast, is a political and moral movement based on a set of beliefs about nature and the human place within it.
Environmentalists want to stop polluting wells and protect bald eagle nests. But they see the well water not so much as property but as part of a natural cycle with its own value that needs to be maintained. The eagle, for its part, is a constituent of an ecosystem that has an essential integrity that should be protected. Any set of beliefs about the workings of the world is perforce a statement about what is good and important in that world. Environmentalism is an argument that respecting the rules of nature is indispensable to having a good society and living a good life. Leopold was among the first to set this idea down. “A thing is right
when it tends to preserve the integrity, stability, and beauty of the biotic community,” he wrote in “The Land Ethic,” one of his most celebrated essays. “It is wrong when it tends otherwise.”
Road to Survival had two main innovations. The first, as the environmental historians Paul Warde and Sverker Sörlin note, was introducing “the idea of the environment.” The old idea of “environment” dates back at least to the ancient Greeks. It meant the external natural factors—climate, soil, altitude, and so on—that affected both individual people’s lives and (it was thought) characters. Thus, for example, Hippocrates believed that fertile, well-watered terrain created people who were “fleshy, ill-articulated, moist, lazy, and generally cowardly.” Hippocrates, raised on the Mediterranean coast, claimed that its environment produced tall, beautiful, intelligent people—people, presumably, like himself and his readers. Variants of this idea continued well into the twentieth century.
In this context, “environment” referred to a single type of place—forests, shorelines, marshes, and so on—that acted on people. As Warde and Sörlin emphasize, Vogt turned the word around. In Road to Survival, “environment” meant not the external natural factors that affected humans but the external natural factors that were affected by humans. Instead of Nature molding people, Vogt envisioned people molding Nature, usually negatively. And by “environment” he meant not a particular place, but a global totality. A statement about the effects of local conditions on people in the past and present had become a vision of humankind’s impact on the entire Earth, with a focus on the future.
Defining a word in a new sense seems academic and abstract, but its consequences are not. Until something has a name, it can’t be discussed or acted upon with intent. “People, by naming the world, transform it,” wrote the Brazilian educator Paulo Freire. Without “the environment,” there would be no environmental movement.
In the second of Road’s main innovations, Vogt summed up the relationship between humanity and this global environment with a single concept: carrying capacity. It is hard to overstate the importance of this. There are two ideas at the base of today’s globe-spanning environmental movement. One is that Homo sapiens, like every other species, is bound by biological laws. The second is that one of these laws is that no species can long exceed the environment’s carrying capacity.
Coined in the early nineteenth century, the term “carrying capacity” initially referred to the amount of cargo that a ship could hold. Over time it came to refer to the weight or volume of material that could be transported by some type of vehicle—the supplies that a mule train could take into the mountains, for example. In the 1880s the definition expanded to the number of grazing animals that could live in a given range. Working in the Forest Service’s Office of Grazing during the First World War, Aldo Leopold encountered the concept; by transferring it from cattle on pastures to game animals in forests, he made carrying capacity a basic ecological tool. In his textbook, Game Management (1933), Leopold argued that land managers’ task was “enhancing productivity,” which meant manipulating the landscape until it reached its maximum carrying capacity.
In Road, Vogt defined carrying capacity by means of a formula: B - E = C. In this equation, B was the biotic potential, the theoretical ability of that piece of land “to produce plants for shelter, for clothing, and especially for food.” E was the environmental resistance, the practical limitations on the theoretical biotic potential. The actual carrying capacity, C, was never as high as the theoretical biotic potential, because there was always some environmental resistance. Hence B - E = C. Vogt argued that people were degrading the environment (the environment!) so much that E was rising worldwide. In consequence, C—the planet’s capacity to support life—was shrinking.
With carrying capacity, Vogt rewrote Malthus. As the Harvard historian Joyce Chaplin has observed, Malthus offered no evidence in his Essay to prove that farm harvests could only increase arithmetically. Indeed, Malthus’s theory could be restated as the claim that one species (humans) reproduces at a geometrically increasing rate, but other species (farm crops) cannot. No obvious reason exists for this to be true—for humans to be special in this way. As one recalls, Malthus’s evidence for the rapidity of human reproduction came from an article by Benjamin Franklin. But, Chaplin notes, Franklin made clear in the same article that he believed that plants and people reproduced at comparable rates—the opposite of Malthus’s contention.
Instead of concocting some reason why farm crops must be less fecund than people, Vogt used carrying capacity to reset the argument. Carrying capacity was a threshold that could not be surpassed by any species. Yes, Vogt conceded, scientists might be able to use technology to boost harvests enough to outstrip population growth. But the short-term triumph of raising farm output would lead to a long-term calamity. Our species would surpass Earth’s carrying capacity, which would destroy the ecosystems that support us. Carrying capacity could not be avoided. Either people would reduce their numbers and consumption to stay below the world’s carrying capacity—or the ecological devastation wrought by overpopulation would do it for them. In the end, as the ecologist-activist Paul Ehrlich later put it, “Nature bats last.”
Vogt’s argument was intuitively powerful but intellectually shaky. As the Berkeley geographer Nathan Sayre has highlighted, carrying capacity began as a concrete quantity that one could measure. If an individual ship had a carrying capacity of X tons, X was a number that could not change unless the ship was rebuilt. But as the notion of carrying capacity expanded to other forms of transportation, then environments like pastures and forests, and then the entire planet, it stopped being something that one could enumerate easily. It was unclear whether the carrying capacity of an ecosystem was actually a static, measurable entity or if it had a meaningful upper bound. An idea that could be useful on a small scale could become untenable if it was stretched like taffy to wrap over the entire world.
Was the carrying capacity of an individual ecosystem a rule of thumb—the way things happened to work out a lot of the time—or a biological law, something that reflected an underlying physical reality? Was an environment’s biotic potential (and thus its maximum theoretical carrying capacity) a fixed, absolute limit, a value set by Nature, or was it a quantity that could change over time, and thus be influenced by people?
Vogt didn’t answer these questions. But at about the same time that he was writing Road, the Georgia ecologist Eugene P. Odum did answer them, in Fundamentals of Ecology (1953), the first widely used ecology textbook. Yes, Odum said, carrying capacity is a concrete number determined by physical law and measurable in the field. Turning to the S-shaped growth curve found by Gause and others, Odum argued in Fundamentals of Ecology that the carrying capacity is simply the highest bit of the graph—“the upper level beyond which no major increase can occur.” Environments have limits that cannot be ignored or overcome. The walls of the petri dish are real and cannot be surpassed.
Odum’s definition of carrying capacity, novel at the time, today “is virtually universal in textbooks,” wrote the Harvard ecologist James Mallet in 2012, “and has been taught to generations of undergraduates.” I am one of them. In college I learned about carrying capacity from the third edition of Odum’s book, published in 1971; its fifth edition, published in 2009 after his death, was in my daughter’s high school biology classroom.
Today the concept of global carrying capacity has evolved into the idea of planetary boundaries. The boundaries set the environmental terrain “within which we expect that humanity can operate safely,” a team of twenty-nine European and American scientists argued in an influential report from 2009. (It was updated in 2015.) To prevent “non-linear, abrupt environmental change,” they said, humankind must not transgress nine global limits. That is, people must not
1. use too much fresh water;
2. put too much nitrogen and phosphorus from fertilizer into the land;
3. overly deplete the protective ozone in th
e stratosphere;
4. change the acidity of the oceans too much;
5. use too much land for agriculture;
6. wipe out species too fast;
7. dump too many chemicals into ecosystems;
8. send too much soot into the air; and
9. put too much carbon dioxide into the atmosphere.
The researchers provided specific figures for these boundaries; as an example, the ozone in the upper atmosphere (Limit No. 3) should not fall to less than 95 percent of its pre-industrial level. I have omitted the numbers to highlight that the basic argument is as simple as it was in Vogt’s day. Stay within the limits, and people can develop freely. Go beyond the boundaries—exceed carrying capacity—and trouble will ensue.
Vogt wanted “intelligent reasonably literate people with little or no knowledge of ecology or conservation” to read his book. He got more than he had dreamed. His ideas, taken up and reframed by later generations, set the tone for environmental crusades for decades to come. Consume less! Eliminate toxins! Turn down the thermostat! Eat lower on the food chain! Reduce and recycle waste! Protect biodiversity! Live close to the land! Protect local communities! Small is beautiful! All have their root in Vogt’s call to live lightly on the soil and work with nature, instead of overwhelming it.
Like many of his followers, Vogt believed that the kind of humble, locally focused, community-oriented life that he invoked was a logical consequence of the recognition of limits, both environmental (the need to respect global carrying capacity) and human (lack of knowledge about ecological interactions). But these injunctions are also inextricably bound to a conception of the good life—a particular way of living that critics mock with epithets like “tree-hugging” and advocates invoke with terms like “sustainability.”