Demographers aren’t known for their sense of humor, but the ones whowork for the United Nations recently announced that the world’s humanpopulation will hit 7 billion on Halloween this year. Since censuses and other surveys can scarcely justify such a precise calculation, it’stempting to imagine that the UN Population Division, the data shop thatpinpointed the Day of 7 Billion, is hinting that we should all beafraid, be very afraid.
We have reason to be. The 21st century is not yet a dozen years old, and there are already 1 billion more people than in October 1999 — with the outlook for future energy and food supplies looking bleaker than it has for decades. It took humanity until the early 19th century to gain itsfirst billion people; then another 1.5 billion followed over the nextcentury and a half. In just the last 60 years the world’s population has gained yet another 4.5 billion. Never before have so many animals ofone species anything like our size inhabited the planet.
And this species interacts with its surroundings far more intensely than any other ever has. Planet Earth has become Planet Humanity, as weco-opt its carbon, water, and nitrogen cycles so completely that noother force can compare. For the first time in life’s3-billion-plus-year history, one form of life — ours — condemns toextinction significant proportions of the plants and animals that areour only known companions in the universe.
Did someone just remark that these impacts don’t stem from our population, but from our consumption? Probably, as this assertion emerges often from journals, books, and the blogosphere. It’s as though a geometry text were to propound the axiom that it is not length that determines the area of a rectangle, butwidth. Would we worry about our individual consumption of energy andnatural resources if humanity still had the stable population of roughly 300 million people — less than today’s U.S. number — that the speciesmaintained throughout the first millennium of the current era?
It is precisely because our population is so large and growing so fastthat we must care, ever more with each generation, how much we asindividuals are out of sync with environmental sustainability. Ourdiets, our modes of moving, and our urge to keep interior temperaturesclose to 70 degrees Fahrenheit no matter what is happening outside —none of these make us awful people. It’s just that collectively, thesebehaviors are moving basic planetary systems into danger zones.
Yet another argument often advanced to wave off population is theassertion that all of us could fit into Los Angeles with room to wiggleour shoulders. The image may comfort some. But space, of course, hasnever been the issue. The impacts of our needs, greeds, and wants are.We should bemoan — and aggressively address — the gross inequity thatcharacterizes individual consumption around the world. But we shouldalso acknowledge that over the decades-long span of most humanlifetimes, most of us are likely to consume a fair amount, regardless of where and how we live; no human being, no matter how poor, can escapeinteracting with the environment, which is one reason population matters so much. And given the global economic system and the developmentoptimistically anticipated in all regions of the world, we each have atendency to consume more as that lifetime proceeds. A parent of sevenpoor children may be the grandparent of 10 to 15 much more affluent ones climbing up the ladder of middle-class consumption.
This, in fact, is the story of China, often seen not as an example ofpopulation’s impact on the environment but that of rapidindustrialization alone. Yet this one country, having growndemographically for millennia, is home to 1.34 billion people. Onereason the growth even of low-consuming populations is hazardous is that bursts of per-capita consumption havetypically followed decades of rapid demographic growth that occurredwhile per-capita consumption rates were low. Examples include the United States in the 19th and 20th centuries, China at the turn of the 21st,and India possibly in the coming decade. More immediately worrisome from an environmental perspective, of course, is that the United States andthe industrialized world as a whole still have growing populations,despite recent slowdowns in the growth rate, while already living highup on the per-capita consumption ladder.
Many of the impacts of this ubiquitous multiplication of per-capitaresource consumption by the number of individuals are by now welldocumented. Humanity started to overwhelm the atmosphere with greenhouse gases not long after the Industrial Revolution began, a process thataccelerated along with population and consumption growth in the 20thcentury. Fresh water is now shared so thinly that the United NationsEnvironment Program (UNEP) projects that in just 14 years two thirds ofthe world’s population will be living in countries facing water scarcity or stress. Half of the world’s original forests have been cleared forhuman land use, and UNEP warns that the world’s fisheries will beeffectively depleted by mid-century. The world’s area of cultivated land has expanded by about 13 percent since its measurement began in 1961,but the doubling of world population since then means that each of uscan count on just half as much land as in 1961 to produce the food weeat.
For the rest of life on Earth, the implications of all this are obvious. Where we go, nature retreats. We are entering an epoch scientists have begun calling the Anthropocene, a break with the geologic past marked by humanity’s long-term alteration of the natural world and its biota. We are inadvertently bringing on the sixth mass extinction not justbecause our appetites are vast and our technologies powerful, butbecause we occupy or manipulate most of the land in every continentexcept Antarctica. We appropriate anywhere from 24 percent to nearly 40percent of the photosynthetic output of the planet for our food andother purposes, and more than half of its accessible renewablefreshwater runoff.
Given these facts, it’s hardly surprising that wildlife conservationfaces an uphill battle globally and in every nation, while ambitiousconcepts like the creation of wildlife corridors to help species escapethe ravages of development and climate change proliferate despite theirimpracticality in a world of growing human impacts.
So should we be afraid on the day we gain a 7 billionth living humanbeing, especially considering UN demographers are now projectinganywhere between 6.2 billion and 15.8 billion people at the end of thecentury? Fear is not a particularly productive response — courage and adetermination to act in the face of risk are the answer. And in thiscase, there is so much to be done to heal and make sustainable a worldof 7 billion breathing human beings that cowering would be not justfatalistic but stupid.
Action means doing a lot of different things right now. We can’t stopthe growth of our numbers in any acceptable way immediately. But we canput in place conditions that will support an early end to growth,possibly making this year’s the last billion-population day we evermark. We can elevate the autonomy of women to make life-changingdecisions for themselves. We can lower birth rates by assuring thatwomen become pregnant only when they themselves decide to bear a child.
Simultaneously, we need a swift transformation of energy, water, andmaterials consumption through conservation, efficiency, and greentechnologies. We shouldn’t think of these as a sequence of efforts —dealing with consumption first, because population dynamics take time to turn around — but as simultaneous work on multiple fronts. It would benaïve to believe we will arrive at sustainability by wrestling shiftingtechnologies and lifestyles while human population grows indefinitelyand most people strive to live as comfortably as Americans do. Norshould we take comfort in the illusion that population growth is already on a path to end soon. Demographers can no more tell us when that willhappen (or through what combination of lower birth rates or higher death rates) than economists can predict when robust global economic growthwill resume. Both expert groups are mocked by the many surprises thefuture holds in store.
Rather than forecast the future, we should work to secure it. More thantwo in five pregnancies worldwide are unintended by the women whoexperience them, and half or more of these pregnancies result in birthsthat spur continued population growth. Clearly there is vast potentialto slow that growth through something women want and need: the capacityto decide for themselves when to become pregnant. If all women had thiscapacity, survey data affirm, average global childbearing wouldimmediately fall below the “replacement fertility” value of slightlymore than two children per woman. Population would immediately move onto a path leading to a peak followed by a gradual decline, possibly wellbefore 2050.
Despite the obvious barriers to women’s rights in today’s world, such avision rests on a set of straightforward and achievable conditions:Women must be able to make their own decisions free from fear ofcoercion or pressure from partners, family, and society. They must notdepend on prolific motherhood for social approval and self-esteem. Andthey must have easy access to a range of safe, effective, and affordable contraceptive methods and the information and counseling needed to usethem.
For those who care about the environment, the future of humancivilization, or both, the Day of 7 Billion should prod us to face andaddress the risks of continued population growth. By the sheer scale of our presence and activity we are putting ourselves and all life at risk. Nohuman being has the right to consume forever more than any other. Yet if we could somehow close the global consumption gap, the importance ofour numbers would be even more obvious as the limits of natural systemswere crossed. It scarcely lessens the importance of reducing bothconsumption and inequity to celebrate the fact that population growthcan end without policies that restrict births, without coercion of anykind, without judgments on those who choose large families. We are notfar from a world in which the number of births roughly balances thenumber of deaths, based on pregnancies universally welcomed by women and their partners.
The transition to this world may not be entirely painless. Nations willhave to adjust to rising average ages as birth rates descend further. In China and India, smaller families may contribute to artificially highratios of baby boys, with possible risks to future social stability. But these problems are the kind that societies and institutions aregenerally good at handling. Stopping climate change, reducing waterscarcity, or keeping ecosystems intact, by contrast, don’t yet seem tobe in our skill set. Working now to bring population growth to an endthrough intentional childbearing won’t solve such problems by itself,but it will help — a lot. And such an effort, based on human rights andthe dignity and freedom of the world’s childbearers, is in the interestof all who care about a truly sustainable environment and human future.