The Big Ratchet: How Humanity Thrives in the Face of Natural Crisis (4 page)
Read The Big Ratchet: How Humanity Thrives in the Face of Natural Crisis Online
Authors: Ruth DeFries
The demise of the Irish potato in the mid-1800s and the many other twists of nature that we will see in this book may seem like classic cases of overshoot. A twist of nature for more food is followed by a society with more and more mouths to feed. At some point, nature reacts. A crash follows. The American sociologist William Catton Jr. described this pattern in his 1980 book
Overshoot: The Ecological Basis of Revolutionary Change
.
From a short lens, history illustrates many individual examples of overshoot. Towering statues of Easter Island, Mayan cities, the cliff dwellings of the Anasazi in the American Southwest, and the massive temple complexes of Angkor Wat in Cambodia all convey the demise of civilizations that once prospered. Some complicated combination of political strife, unexpected climate, social upheaval, or soils run dry of nutrients, as well as many unknowable factors,
no doubt contributed. All of these civilizations had ratcheted up their numbers with sophisticated technologies, and none withstood the onslaught from intertwined social and ecological changes.
The short lens and a focus on those particular examples bias our interpretation of the past. The long lens paints a different picture, showing that overshoot leads not to collapse, but to the next pivot. This is the argument of the Danish economist Ester Boserup, who studied so-called primitive societies. Boserup claimed that when too many hungry stomachs
outstrip the available food supply, people work harder to produce more food by
weeding and watering the crops. Instead of overshoot and ensuing collapse, human ingenuity kicks in. The pivot follows the hatchet. Individual societies may rise and fall, but for the species, the trajectory follows a path of successive ratchets and pivots.
The Boserupian view leans on human ingenuity to find pivots for ratchets. The environmentalists’ idea of overshoot assumes that nature will run out of pivots. Neither of these views is sufficient in itself to explain the billions-strong dominance of our species on the planet, or to guide society’s decisions about the future. If the bag of ecological tricks runs out, or if nature’s backlash is so overpowering that no pivot can evolve quickly enough to help, then overshoot could truly ensue. So far, and in aggregate, though, history tells the opposite story. Humanity’s manipulations of nature have transformed the planet’s landscapes and ratcheted up our numbers again and again. By measures of numbers and extent, our species has achieved extraordinary success.
The Big Ratchet of the twentieth century brings us to a quandary. As described in later chapters, at no other time in history has food been so abundant, or our species so successful in expanding in numbers. At no other time have so many people been so prosperous. On the other side of the ledger, the gap between the rich and the poor has grown wider, the manipulations of nature have become more massive, and diets have become more loaded with unhealthy sugars and fats. Although history shows that ingenuity has brought humanity back from the brink of overshoot time and again, this history does not ensure that the same will occur in the future.
Without Socrates’s bird’s-eye view, it is difficult to tell where the present stands in the long arc of history. We would be, as the nineteenth-century philosopher Arthur Schopenhauer wrote, like “every man” who “takes the limits of his own field of vision for the
limits of the world.”
This book looks at the current times through the lens of the long arc of our species’ quest to feed itself. From the multimillennia lens of ratchets, hatchets, and pivots, two themes emerge. One is that the ratchets, hatchets, and pivots will continue as long as human civilization exists. Solutions will create new problems, and problems will generate new solutions. The other is that we live in extraordinary times, at the crest of a ratchet that has manipulated nature so much that most of humanity can live in cities rather than grow their own food. Today’s transformation from a farming to an urban species is as momentous for our lives and the planet as the long-ago transition from forager to farmer. We have yet to learn how to live with that change.
The story of humanity’s journey from an ordinary mammal to a world-dominating species goes back millions, if not billions, of years. Only a planet with an amazing machinery to sustain the richness of life could give rise to an intelligent, large-brained species such as ours. Only an exceptional species with culture and knowledge could manipulate nature and produce enough food to dominate the world.
To recount the story of humanity’s interplay with nature through a long-term lens is to bear witness to astonishing feats of human ingenuity that both solved problems and created new ones in their wake. The story begins with the two foundations that made our evolution from an ordinary mammal possible—endowments from a bountiful planet and the power of ingenuity. The amazing marvels of our planet’s machinery, combined with the ingenuity of our species to harness that machinery for food, is the platform on which all civilization rests. As we leave aside the blithe reassurances of those who assume that technological fixes are always in store and the frenetic warnings of the doomsayers, we embrace a broader understanding of the interlocked path of human civilization and the planet. Only by acknowledging the long and complex interplay of nature and human ingenuity can we begin to address the next pivots that may be in store for our remarkable species.
V
ENUS IS TOO HOT
. Mars is too cold and too rocky. In our solar system and beyond, as far as we know, our planet is the only one that provides the basic machinery for a nature-manipulating, intelligent species like ours to prosper. The tale of humanity’s journey from ordinary to urban begins with the story of this machinery.
Perhaps Enrico Fermi—the brilliant World War II–era physicist renowned for setting off a nuclear chain reaction in a squash court—was pondering these marvels of our planet one summer day. During casual lunchtime conversation with his colleagues at the Los Alamos National Laboratory several years after the war’s end, Fermi
posed a basic question: Why hasn’t there been any communication from life elsewhere in the universe? Life, he argued, must exist somewhere else. Surely out there somewhere is a species with technology more advanced than our own, and certainly they have the know-how to communicate with us. Fermi’s famous quip over lunch—“Where is everybody?”—became “
Fermi’s paradox.” With such a high chance of intelligent life elsewhere in the universe, why haven’t we heard from them?
Hypotheses abound to answer Fermi’s paradox. One line of reasoning claims that our planet is, if not unique, different enough that similar planets supporting complex life are rare in the universe, even though simple life, such as microbes and single-celled organisms,
might be more common. Another line of reasoning argues that perhaps our planet is not so special after all, that the Earth is just another rocky, mediocre planet in an unexceptional solar system. Complex life abounds, and only time stands in the way of finding it.
Fermi’s paradox has captivated astronomers and astrobiologists as they search for planets around other stars. In essence, they are searching for other planets suitable for intelligent life forms—planets in which ingenious species can
evolve and thrive. And the more they look, the more they find that the Earth does share the universe with millions, maybe billions,
of other planets. As the number of known planets grows, so, too, do the odds of finding intelligent life.
Regardless of what the universe might hold, our planet is a spectacular platform for the interplay of human ingenuity and nature. Without the planet’s basic machinery, there would be no life and no civilization, and certainly no single species like our own that could spread its reach across the planet. Most of this basic machinery is well beyond humanity’s control, no matter how sophisticated we might become. We cannot change the planet’s distance from the sun; nor can we speed up the tectonic plates that carry continents across the Earth’s surface, force blasts from volcanoes, or cause the Northern Lights to glow. These are just a few of the many features of our world that are beyond our control but still deeply entwined with humanity’s journey from ordinary to urban.
That might seem an odd claim. Surely what matters is simply growing enough food to feed so many people. But without a planet that can provide nourishment and habitat for a wide variety of plant and animal species, even the most intelligent life forms could not manipulate nature to produce food on such a grand scale. A confluence of fundamental
features collectively forms the foundation for life on our planet. The Earth has the right location in the solar system, an internal magnet, the machinery necessary for regulating greenhouse gases and recycling nutrients, and, above all, a long enough period of time with a stable enough climate to support varied forms of life as they evolved. Together, these features satisfy three fundamental requirements for a planet that can support an ingenious species such as ours: a stable climate, a planetary recycling apparatus, and a smorgasbord of life. These features were present on Earth long before humans walked on the planet, and they will likely be present long after humans have left the scene.
For a planet, location, as for real estate, is the first crucial feature. Distance from the sun is paramount. This distance dictates whether liquid water—the solvent in which life emerged on Earth and the substance that sustains life—is present. Perhaps other solvents supporting other forms of life exist somewhere in the universe, but until we find evidence to the contrary, liquid water remains a requisite for life, at least life analogous to Earth’s. If a planet is too far from the sun, any water it might have will be in the form of ice. If a planet is too close, any water will be in the form of water vapor in its atmosphere. Those two boundaries—the distance where water turns into a solid and the distance where it turns into a gas—create a donut-shaped ring around a sun where enough water will remain liquid for life to develop and survive. This ring is the Habitable Zone, prime real estate in the solar system. A planet that orbits within the Habitable Zone (HZ) has
a chance for life.
Add another complication. The amount of heat from the sun does not stay constant through time. When the Earth was in its infancy, the sun was about a third less powerful than it is today. A billion or so years hence, it will become so hot that water on Earth’s surface will boil away.
In a few billion years more, when the sun will have used up much of its internal fuel, it will swell into a fiery red giant and swallow our entire planet before collapsing into a
fading white dwarf. On human time scales, the Earth’s slow deterioration into waterless barrenness and eventual annihilation by an aging star is irrelevant. For the Habitable Zone, it means that the prized real estate moves farther away from the center of the solar system as the sun’s energy intensifies. A planet close to the edge can slip out of the Habitable Zone just by staying in the same place. A planet where life can evolve must be not just in the Habitable Zone, but in the Continuously Habitable Zone, the zone that remains habitable over a long enough time for complex animal life to evolve. Our planet has been in the Continuously Habitable Zone for some 5 billion years, and it will
remain there for a billion more.
But distance alone does not determine whether water on a planet is liquid, gas, or solid. If distance were the only factor, our planet would be a frozen expanse of ice instead of liquid water. The atmosphere’s blanket-like greenhouse effect—so often invoked with specters of human-caused catastrophe—saves our planet from a fate similar to that of icy Mars. Greenhouse gases allow solar radiation to penetrate the atmosphere but keep some of the planet’s heat from escaping back into space. The greenhouse effect raises the Earth’s average temperature from well below freezing to a hospitable 60 degrees Fahrenheit. Water vapor is the most abundant among these gases.
