THE CENSUS BUREAU, among the snippets of demographic data it releases almost daily, reports that the US population now clocks in at 281 million — an increase of 30 million in just the past 10 years. The agency projects that the US will house 403 million people by 2050; its highest estimate tops half a billion. World population has moved even faster on the same rocket-like trajectory. A century ago, there were 1.6 billion people on earth; today, that number has nearly quadrupled, to more than six billion. The planet has never before supported this many people — and the United Nations projects that world population won’t stop growing until it hits 10 billion in 2183, after which it will stay the same or decline slightly.

Explosive population growth has worried observers since the 18th century. In 1798, the English economist T.R. Malthus predicted in An Essay on the Principle of Population that rampant competition for scarce natural resources would cause starvation and misery. Fears about overpopulation hit a fever pitch in the late 1960s and 1970s, when population growth reached an all-time high thanks to medical and technological advances that lowered death rates while birth rates remained constant. Stanford biologist Paul Ehrlich’s 1968 publication of the dystopian manifesto The Population Bomb (Ballantine Books) scared the masses into awareness with predictions that overpopulation would cause a fifth of the world’s population to starve to death by 1985, while pollution would lower the quality of life for everyone else. His frequent guest appearances on The Today Show — and even The Tonight Show with Johnny Carson — spread the word far and wide.

But a funny thing happened on the way to the apocalypse. The world is a better place today than it was 30 years ago. Thanks to unexpected environmental and agricultural advances, such as the development of heartier strains of rice, Ehrlich’s dire predictions never came true. Indeed, a report released last fall by the National Intelligence Council — an arm of the CIA — says that mass starvation is no longer a threat. (Though famines do still occur, they are almost always a result of political strife rather than a failure in food production.) And despite ongoing concerns about issues such as global warming, the environment is in many ways cleaner. Since the US Environmental Protection Agency was created in 1970, stricter and better-enforced laws have reined in one of the globe’s worst polluters. That year, for instance, America pumped 220,869 tons of lead into the air. By 1998, the number had shrunk to 3973 tons. Concern for the environment has also grown internationally; major UN treaties now address ecological problems such as hazardous waste and endangered species. Developed countries banned production of ozone-depleting chlorofluorocarbons in 1996; two years ago, such chemicals were outlawed worldwide.

“If you want to say I was not 100 percent accurate,” says Paul Ehrlich of his environmental predictions, “you’re right. Scientists give their best estimate.” He firmly believes that overpopulation is still a danger, and he notes that the scientific community backs him up. In 1992, Linus Pauling, Carl Sagan, and 1573 other scientists — 100 of them, like Pauling, Nobel Prize winners — signed a “Warning to Humanity” letter, which detailed overpopulation’s threat to the environment. But thus far history has shown — to retool a phrase of Gordon Gekko’s — that growth is good.

The late Julian Simon, a business professor at the University of Maryland who once described human ingenuity as the “ultimate resource,” argued that natural resources actually were becoming less scarce over time because humans invariably developed better and cheaper ways to obtain them, or created new technologies that rendered them obsolete. He was so certain of this that he made a bet with Ehrlich in 1980 that the price of any natural resource Ehrlich picked would — at any point in the future — be lower. Ehrlich, convinced that scarcity would drive up costs, wagered on chrome, copper, nickel, tin, and tungsten. Ten years later, the price of all five metals had dropped sharply. Metals had largely given way to plastics; copper had been supplanted by fiber optics. And Simon — with history to back him up — was again proven right in his belief that “the standard of living has risen along with the size of the world’s population since the beginning of time. There is no convincing economic reason why these trends toward a better life should not continue indefinitely.”

So Ehrlich may be Chicken Little, recklessly raising false alarms. But what about, say, global warming? Though Simon’s case is convincing, it may be inviting humanity to play a high-stakes game of chicken with the planet.

WHO’S RIGHT, Ehrlich or Simon? They’re both right. They’re also both wrong — depending on whether you’re a middle-class American or a farmer in Ethiopia.

“There are parts of the world now where people are pushing the limits of what people can do,” says John Haaga of the Population Reference Bureau. “You can say, ‘Never mind the planet as a whole — how many people can the Middle East hold?’ Those questions will become relevant long before the science-fiction question of how many people the earth can hold, because the earth isn’t a relevant political unit.” As Ehrlich points out, less-developed areas are still struggling with the familiar peril of overpopulation — and Simon’s view that more people mean more brainpower and innovation offers little comfort to nations suffering from a lack of infrastructure such as schools and hospitals and, at least in the short term, of natural resources like fresh water. Ehrlich also contends that wealthy Western nations are overpopulated in the sense that they consume too many resources. Americans, for instance, use 1512 gallons of water each day per capita; the world average is only 465 gallons.

Advocates and governments have made dramatic progress in the continuing mission to reduce population. The Third World’s fertility rate has dropped substantially — from six children per couple in 1970 to three today, according to the UN. “People in the early ’70s were talking about coercive methods” to stop reproduction in Third World nations, says Haaga. “They said, ‘You can’t just make safe family planning available, because that’s not enough.’ ” Although China still prohibits families from having more than one child each, experience in other developing nations has shown that population growth can be managed voluntarily, with the help of contraception and access to abortion. “Now there’s plenty of evidence that given the choice, particularly where women are educated and given a say in the matter, people want to use contraception and to space their births,” Haaga says.

Meanwhile, even as the public’s attention has been riveted by overpopulation, the opposite threat — of too few people — has emerged in every developed country except the United States. It’s serious enough that the National Intelligence Council’s report Global Trends 2015 predicts that global economic growth will be compromised if Europe and Japan don’t deal with the problem. The birth rate in Western Europe was 1.58 children per family in 1997; Japan clocked in at 1.39 children; Italy, with a rate of 1.2, had the lowest levels ever recorded. Populations in these areas simply are not sustaining themselves. The low birth rates “are unfathomable, unsustainable, and mind-boggling,” says population scholar Ben Wattenberg of the American Enterprise Institute. He adds: “Something is going on in the world that’s never happened before, not even close. There’s a fall in birth rates without a war or a plague or a famine, and we don’t have a clue how to deal with it.”

John Bongaarts, vice-president of the Population Council, spells out the problem: “You have just too few workers to pay the taxes to take care of the health care of the elderly people. Something is going to have to give — the older people will have to get less or the taxes will have to go up.” Though workers could simply retire later in life, no option on the table is politically palatable — and as elected officials know, retirees are downright aggressive about protecting their benefits. Without serious measures, the shortfall could spark a global economic crisis. And nations could be changed or destroyed as their populations die out.

A steady rate of population growth therefore has some clear advantages — and, at least physically, it’s still feasible. Even Zero Population Growth, a nonprofit organization dedicated to fighting overpopulation, admits on its Web site that everyone in the world — all six billion people — could fit in the state of Texas, with enough room for each to have a two-bedroom apartment. Not that the population could be sustained. The group estimates that a human being needs .17 acres of land to grow enough food to live; if Texas were the world, each person would have just .028 acres. But still — there’s clearly room for expansion.

In order to mitigate the economically damaging potential of an aging population, and to continue the output gains and technological advances of recent years, it may be time for notoriously xenophobic countries like Japan to accept more immigrants from overpopulated developing countries. Another solution may be to woo prospective parents. “I don’t think anyone would say you should start forcing Italian women to have babies,” says Jay Keller of Zero Population Growth, and that’s true. But possible government incentives abound. Sweden, among other countries, has generous family-leave and flex-time policies. Even the US, which isn’t known for its family-friendly policies, offers a tax credit of $500 per child. In Japan, self-interested corporations are also getting into the act: Bandai, a toy company that makes Power Rangers and Tamagotchis, last year began offering employees $10,000 for each child they have after their second. The move, according to the New York Times, “was intended to help employees defray the high cost of raising children and to expand the company’s shrinking customer base — children.” But any such solution — whether it’s loosening immigration restrictions, offering incentives to parents, or tinkering with retirees’ pension benefits to make sure there’s enough to go around — would be likely to face fierce political opposition.

ONE THING scientists know for sure is that humanity’s future — even in the immediate sense — depends on solving certain environmental problems that are caused, at least in part, by human activity. Though the threat of mass starvation has come to naught (and critics such as Nicholas Eberstadt, a visiting fellow at Harvard’s Center for Population and Developmental Studies, accuse the overpopulationist crowd of finding a new eco-bogeyman every time one of the previous predictions fails), reputable scientists and organizations are taking three major issues seriously.

The first is fresh water: even in the next 15 years, shortages may reach crisis levels. A 1997 UN study showed that up to a third of the world’s population may be at risk for water shortages; the Global Trends report predicts the scarcity could lead to political strife in the Middle East, sub-Saharan Africa, South Asia, and Northern China. Desalinization of salt water can help, but simply isn’t feasible on a large enough scale to meet demand. Perhaps a revolutionary new technology will be developed — something akin to the strains of rice that improved Third World nutrition 30 years ago. But there are no guarantees.

Global climate change (which Ehrlich also predicted back in 1968) appears to be another real danger as more cars and power plants pump carbon dioxide into the air. The gas is harmless by itself; in fact, it’s a necessary part of nature. But in large quantities, it can trap heat on the earth and potentially alter ecosystems. The 1990s were the warmest decade ever recorded, and environmentalists are concerned that the policies of President Bush — who recently decided not to limit carbon dioxide emissions from power plants — may make matters worse. Even the related issue of acid rain, which retreated from public consciousness with the passage of the 1990 Clean Air Act, is still a threat. This week, a team of scientific experts reported that sulfur dioxide emissions, which also come from power plants and are the chief cause of acid rain, must be slashed another 80 percent to stop the deterioration of soil and rivers.

Solutions to these problems could be within reach. For example, we could use more solar power instead of fossil fuels. Other possibilities include nuclear or hydroelectric power — though the danger of radiation leaks and the disruption of river ecosystems are potential pitfalls. Another promising development is “Ginger,” the mysterious invention created by New Hampshire scientist Dean Kamen and reportedly praised in lofty terms by such high-tech savants as Steve Jobs. Details of the project, which leaked in January, are tantalizingly vague — to judge from drawings Kamen submitted for recent patent applications, it could be something as banal as a motorized scooter or as profound as a Stirling engine, which inventors have been pursuing like a Holy Grail for years because it could make energy production exponentially more effective. But Kamen himself has downplayed speculation.

The third environmental problem on the horizon is the extinction of plant and animal species. Insights into how life developed, or perhaps new life-saving medicines, may be lost every time rain forests and other natural areas are plowed under for development. Harvard biologist E.O. Wilson wrote in a 1993 New York Times piece that even with thousands of scientists and a billion-dollar budget, the prognosis for saving these habitats is bleak: humanity has no idea how to uproot and move an ecosystem away from encroaching development. “Each species occupies a precise niche,” he wrote, “demanding a certain place, an exact microclimate, particular nutrients and temperature and humidity cycles with specified timing to trigger phases of the life cycle. Many, perhaps most, of the species are locked in symbioses with other species; they cannot survive unless arrayed with their partners in the correct idiosyncratic configurations.”

Cloning could help scientists preserve endangered species — or even revive extinct ones — but the jury is still out on Dolly and friends, and on whether cloning causes genetic defects. In January, scientists in Iowa successfully orchestrated the birth of an endangered ox called the Asian gaur — to a cow. The gaur lived only two days, but scientists claim the death was not a result of the cloning process. However, the secrets of ecosystem management remain beyond our grasp; even simple questions, such as how to entice animals to breed in captivity, continue to elude scientists. Clearly, governments need to evaluate development even more carefully — especially in ecologically sensitive areas — to balance economic growth with environmental preservation.

There’s no question that humanity has seen a dramatic increase in quality of life — the near-sighted have gone from being eaten by lions to wearing glasses to wearing contacts to having laser surgery. Mortality rates have plummeted; nutrition and health in many parts of the world are better than they have ever been. Even the environment, once despoiled by sewage in the streets and unchecked toxic smokestacks, is cleaner and better regulated. History has shown us that population growth fuels innovation and dynamism, and as the developed world grows grayer, sudden population decline sometimes looks like a bigger economic threat than a population boom.

But remember the lesson of the French parable that Wilson, the Harvard biologist, cited in his New York Times piece. A lily pad in a pond will double each day, he wrote. The pond meanderingly adds more lily pads each day in a gentle progression. After 29 days of slow growth, it’s finally half full, and the pond’s residents expect from experience to see a handful more lily pads the next day. But by morning, new lily pads have seized the entire pond. The water is completely covered, sunlight can no longer penetrate to the bottom, and life is choked off. With more people on earth than ever before — and billions more on the way — the question is, how close are we to the breaking point? Are we on the third day, the fifth, the ninth? Or the 29th?

Dorie Clark can be reached at dclark[a]phx.com.

Issue Date: March 29 - April 5, 2001