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The online version of this article appears in two parts. Click here to go to part one.

Trees and Soil

FEW PLACES IN THE United States better illustrate the unforeseen consequences of population growth than the lower valley of the Hudson River, which runs south from Albany to New York City. The river is wide and placid in appearance, and its banks sparkle with towns that were young when the nation was young. To the west rise the Catskills, blue at sunset and blanketed by trees. Interstate 87 makes a ribbon between the water and the mountains. A while ago I spent some time driving on that road, and down long miles of its length the forest stretched out so far and so dark and so empty that I imagined I was looking at the America of a hundred years ago, before there were millions of people like me around. How wonderful, I thought, that so close to Manhattan is a huge piece of real estate that we never trashed.

I was wrong. If I had traveled through the Hudson Valley at the end of the last century, I would have passed through an utterly different landscape. I would have been surrounded by small hardscrabble farms, fields of wheat and corn, and pastures ringed by stone walls. It might have looked picturesque -- certainly guidebook writers of the day thought so. But I wouldn't have seen many trees, because long before, almost every scrap of land that wasn't vertical had been clear-cut or burned.

The forest was stripped to make way for agriculture and to supply New York's army of charcoal-burners (who needed lumber to make charcoal), tanners (who extracted tannin from bark), and salt-makers (who used wood fuel to boil down seawater). Loggers played a role too: Albany, the northernmost deepwater port on the Hudson, was the biggest timber town in the nation and possibly the world. When the first Europeans came to New York, the region was almost entirely covered by trees; by the end of the nineteenth century less than a quarter of the state was wooded, and most of what was left had been picked through, or was inaccessible, or was being kept by farmers as private fuel reserves. During the epoch that I, swooping along the tarmac in my minivan, was nostalgically picturing as a paradise, newspaper editorials were warning that deforestation would drive the valley toward ecological disaster.
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Since then the collapse of small farming has allowed millions of acres to return to nature. When New York State surveyed itself in 1875, the six counties that make up the lower Hudson Valley -- Columbia, Dutchess, Greene, Orange, Putnam, and Ulster -- contained 573,003 acres of timberland, covering about 21 percent of their total area. In 1980, the date of the most recent survey, trees covered almost 1.8 million acres, more than three times as much. (This is no scrubby growth, mind you. Michael Greason, an associate forester in the state's Department of Environmental Conservation, calls today's Hudson and Catskill forest a "beautiful, diverse ecosystem.")

I was driving around the Hudson Valley partly because I was looking for a house in the country. My method of looking, insofar as one could call it a method, was to hunt in the counties with the lowest populations, figuring that they would be the least spoiled. I was trying to get away from people, and from the unpleasantness I associated with urban life. The more crowded an area, I thought, the more degraded its environment. I wanted natural beauty, and that meant "uninhabited."

Learning some local history gave me pause. Back in 1875 my six counties had a collective population of 345,679. The U.S. Census says the figure for 1990 was 924,075. In other words, the number of people living there almost tripled in the same period that the local ecosystem climbed out of its sickbed and threw away its crutches. This wasn't just some odd thing that happened in New York. As a whole, American forests are bigger and healthier than they were at the turn of the century, when the country's population was below 100 million. Massachusetts and some other states have as many trees as they had in the days of Paul Revere. Nor was this growth restricted to North America: Europe's forest resources increased by 25 or 30 percent from 1970 to 1990, a time in which its population grew from 462 million to 502 million. Presumably the forest figure would have been yet higher without the continent's damaging acid rain.

People pollute. But more people does not always mean more pollution. Eco-critics can claim, with some justification, that the forests of the Hudson Valley recuperated because farmers abandoned them in order to wipe out the native grasslands of the Great Plains. But they can't explain away all the good news. Salmon are reintroduced to the Thames. White-tailed deer, almost extinct in 1900, plague New England gardens. Air quality in Tokyo improves remarkably. Wild turkeys have a greater range than they did when they were first seen by white settlers. If all this occurred during the population boom, why the belief, now frequently voiced, that overpopulation will lead to an eco-catastrophe?

"You can look at Lake Erie or Detroit and see it's gotten better," says Dennis L. Meadows, the leader of the research group that produced The Limits to Growth."But to leap from that to the conclusion that there has been overall improvement is to look at one person getting rich and say that everybody is better off." Now at the helm of the Institute for Policy and Social Science Research at the University of New Hampshire, Meadows, with two co-authors, has recently published a sequel, Beyond the Limits,which is even more pessimistic than the first book. "When a rich country becomes concerned about environmental problems," Meadows says, "then it can typically develop effective responses." Lead additives in gasoline became a subject of American worries. The nation forced petroleum companies to phase out leaded gas, and lead levels diminished. Similar fears have led twenty-three industrialized countries since 1987 to halve the rate of release of the worst ozone-eating compounds. In Meadows's view, rich countries have the wealth to buy their way out of many such difficulties. But other difficulties remain, and their number grows. Soil erodes; draining ruins wetlands; contaminants infiltrate groundwater; toxic wastes keep accumulating. The situation is much worse in poor countries that cannot pay to clean themselves up. Behind all the concerns is the specter of growing numbers, of insatiable human wants, of continually increasing demand. "We're trying to sustain physical growth on a finite planet," he says. "Growth will stop in our lifetime." Meadows, who is fifty, confidently expects to see the end of population growth in his lifetime -- probably through ecological breakdown.

Cassandras like Meadows, Ehrlich, and Lester Brown, of Worldwatch, regard land degradation as one of the worst and most obvious ecological consequences of crowding too many people into too little space. "Land degradation" is a catchall term covering such problems as wind and water erosion, soil pollution by urban wastes or pesticides, and the buildup of mineral salts caused by improper irrigation. The term may bring to mind newspaper photographs of faraway African husbandmen in terrain nibbled to exhaustion by cattle. But environmentalists say the problem is bigger than that -- "virtually a worldwide epidemic," in the words of Anne Ehrlich, a research associate at Stanford University, a veteran Cassandra, and the wife of Paul Ehrlich. The International Soil Reference and Information Centre (ISRIC), in the Netherlands, estimates that since 1945 Homo sapienshas degraded 17 percent of the world's land, not counting wastelands like Antarctica and the Gobi Desert. Two thirds of the devastated area will require major restoration.

Every year, Brown warns, erosion steals 24 billion tons of soil from the world's farmers -- a figure that the ecology-minded cite as plain evidence that humanity is exceeding the carrying capacity of the planet. The economics-minded see rhetoric and hand-waving. "Those figures Lester Brown is going on are based on really wild assumptions," says Pierre Crosson, a senior fellow at Resources for the Future, a nonprofit research group in Washington, D.C. "He's taking poorly understood sedimentation figures from big river deltas and extrapolating them to get a figure for productivity loss for the whole world." As for the ISRIC study, Crosson points out that it classifies most of Illinois, Iowa, Kansas, Nebraska, and the Dakotas as degraded enough to "greatly reduce" productivity. "The problem with this," he says, "is that in those six states yields have risen steadily over the last forty years."

The United States has the most carefully measured soil in the world. Every five years the U.S. Department of Agriculture evaluates the nation's land, county by county, in terms of something called "the universal soil loss equation," which assesses the soil movement in a given area. Because the equation measures movement rather than absolute disappearance, the results are hard to evaluate; they don't distinguish between soil that ends up on the bottom of the ocean and soil that is merely shifted to a neighbor's property, enriching yields there. (Sometimes the neighbors are far away: according to measurements by atmospheric scientists at the University of Virginia, more than 13 million tons of rich African soil are blown every year onto the Amazon forest floor.) In the 1980s three independent studies, one by Crosson, used the data to estimate actual soil loss. All concluded that the peril to U.S. agriculture from erosion is negligible. "The Soil Conservation Service is doing its job," Crosson says.

It is hard to be as sanguine about the developing world. Sub-Saharan Africa, for instance, is often described as a place where overpopulation has led to a terrible destruction of land. The region has high birth rates; per capita food production has consistently fallen in the past ten years. Rainless years in the same period led to overgrazing, deforestation, wide-scale erosion, and the hunger shown in sad televised images. Civil strife and famine have driven at least two million people from their homes. The desert is said to be marching south at a rate of five to six miles a year, a scary prospect that Cassandras regard as dramatic evidence of Africa's population quandary.

No one doubts that Africa is in a dire position, but the Pollyannas think that the problem is bad luck, bad weather, and bad planning. Traditionally, African villagers often held land in common, with access regulated by unwritten cultural rules. "In those circumstances," Crosson says, "the people responsible for the management of the land take overuse into account, so they enforce rules of access that limit the use of the land." When modern crops and agricultural techniques appear, the system comes apart, because yields shoot high enough to give people a greater incentive to cheat. If they break the rules, they can make a bundle and skip town with the profit; those who play fair are left with the ruins. (Garrett Hardin calls this the "tragedy of the commons.") Population pressures exacerbate the problem, most economists concede, by shrinking everyone's share of the common land. Add drought or ethnic conflict and the result is disaster. But, they say, African nations without drought or conflict have done increasingly well. Given half a chance, people in Africa, like people anyplace else, seem to make their own way.

The Cassandras base their case "on intuitively powerful hypotheses that slide over the need for empirical verification," says Michael Mortimore, a senior research associate at Cambridge University, England. "Unfortunately, the only way to test them is to collect a large amount of empirical data." Mortimore has spent years gathering information on farms in Nigeria and Kenya. His comparison of contemporary and thirteen-year-old dirt samples in Nigeria, one of Africa's most heavily populated nations, shows that increasing population has, if anything, raisedland productivity. In decades past, farmers could exhaust an area and then move on. Now rising numbers have made land more expensive, and people have greater incentives to take care of what they have. "You're not going to pass on a desert to your children," Mortimore says. Claiming that Africans are otherwise inclined is, to his mind, "straightforward cultural prejudice." The agricultural systems that he studies are "economically, socially, and ecologically sustainable." In Nigeria, he says, the 1992 harvest was the biggest in twenty years.

As for other parts of sub-Saharan Africa, no one denies the famine there. Yet recent independent studies have found no long-termenvironmental consequences of the recent and devastating drought; the southern border of the desert, one study shows, is in about the same place it was eighty years ago, suggesting that the desert expands and contracts with little regard for its human inhabitants. The drought may have led to temporary overuse of common property, economists concede, but the proper response would be to adjust land-use rules -- change the zoning, so to speak -- as societies did in other parts of Africa. That response's alleged failure to occur in sub-Saharan Africa says more about the pervasive corruption, inefficiency, and civil turmoil there than about the inherent evils of breeding.

"You always can blame any particular difficulty on something that is not overpopulation," Dennis Meadows says. "Nobody ever dies of overpopulation. They die of famine, pestilence, and war. There's always some proximate cause." Adjusting land-use rules is desirable in his view, but it does nothing to eliminate the fundamental problem. At bottom, more people means more resource use and more pollution and more loss of biodiversity, all of which must eventually stop. We can't go on forever, because the world is finite. No matter how smart we are, Cassandras say, we can't avoid being part of the web of life, governed by its laws. True enough, the Pollyannas say. But our part in that web is to be different. Other species die when they breed enough to wreck their environments, as they sometimes do. Human beings don't wait to be overwhelmed. When problems arise, we solve them -- that's our nature. This argument makes Cassandras smite their collective brow and deride, as Ehrlich did recently, the "imbeciles running around today saying not to worry, that with the aid of science and technology we can take good care of many billions more."

Thinking Differently

IN NATHAN KEYFITZ'S VIEW, THE ARGUMENT amounts to a classic academic standoff. Keyfitz leads a group of demographers at the International Institute for Applied Systems Analysis (IIASA), a research group in Austria, and is one of the few people I heard praised by both sides in the dispute. Keyfitz recalls attending a meeting at Brandeis University convened with the noble intention of reconciling biologists and economists. For three days speakers from each side stated their points of view, completely ignoring everything the other side had said. Then, apparently satisfied, everyone went home. "Here," Keyfitz has written, "is a nightmare for democratic politics: what action to take on vital questions where the experts disagree violently."

A first step away from the impasse, Keyfitz suggests, might be for each side to accept the validity of the other's arguments, as long as they pertain to that side's discipline. Give the biologists their due, and agree that an increased human presence poses a huge threat to the environment, even if some of the biologists' claims are exaggerated. Then agree with economists that the problems are not due to population growth per se. Instead, population growth changes social and economic systems, which inevitably creates environmental problems: more food must be grown, so that once-adequate agricultural methods now overuse land.

But Keyfitz is hesitant to embrace the next step in the economists' logic. "I think we all know the idea," he says. "As you catch up with these problems one by one, you turn the power of science on them and produce solutions." Sometimes the correction is expensive, Cassandras admit, but thoughtful government policies can minimize the pinch. Here we step outside the boundaries of economics into political science, into arguments nobody has promised to accept. The picture, Keyfitz says, has governments responding wisely -- and, as everyone knows, they often don't. Indeed, an outside observer might find it curious that economists -- disdainful of government in other matters -- exhibit such touching faith in the power of their elected representatives to resolve the troubles exacerbated by rising population.

Even if governments try to respond, they are often unable to anticipate the consequences of their actions. As a means of fostering international communication, Keyfitz says, "the worldwide air-transport network does nothing but good. But it's responsible for the spread of AIDS. Otherwise it would be an unrecognized, unnamed disease in a corner of Africa." With the instant contact possible today, a local problem became a global catastrophe. "You'd like more chance to breathe," Keyfitz says. "I'm not saying that any of these problems are inherently unresolvable by themselves, but we wouldn't be running so fast if the world had half its present population."

As the human presence increasingly dominates the earth, new difficulties emerge at ever greater speed: The ozone layer. The exhaustion of fisheries. The greenhouse effect. The overuse of aquifers. The need to increase yields of tropical foodstuffs. Each must be evaluated, absorbed, treated, even as the next problem appears. The loss of biodiversity. The collapse of the infrastructure. The destruction of rain forests. And on and on. Maybe people can keep up; certainly Keyfitz's colleagues, the computer modelers at IIASA, think so. But in a world where every citizen is surrounded by examples of governmental incompetence, it is hard to imagine that nations will keep coming through, time after time. There'll be so much juggling. So many things will have to be fixed all at once. Societies will find themselves in the position of the antic ninjas in video arcades, hordes of enemies to every side. Whack! Bam! Pow! Eventually, as any adolescent knows, the ninja slips up, and the game is over.

My Madonna Problem

FOR MANY YEARS I HAD AN OFFICE ON THE FOURteenth floor of a building in Manhattan, overlooking a busy avenue. During that time I never had air-conditioning, because it does something to the air that makes my nose run. In hot weather I opened the window. A breeze came in, reducing the temperature to a range I found tolerable. The problem was that it was hard to speak on the phone with the window open. People drove around the city with their car stereo systems cranked up to medically unsafe levels. Abrupt blasts of noise filled the room.

A debacle occurred when I interviewed Mario Cuomo, the governor of New York. Arranging the call involved considerable negotiation with his office in Albany. Two minutes into the conversation Madonna arrived. I had to shout over her moans. The governor did not immediately believe my explanation of the sound's origin. The light changed; the noise went away. I asked him a question. Suddenly Madonna showed up again. I realized that she was circling the block, looking for a parking space. I slammed the window shut, raising the room's temperature by ten degrees. The song was still devastatingly loud. The third time the song came round, I draped my jacket over the window. The fourth time, the governor hung up.

Soon after, I began looking for a house in the country.

The noise, and my response to it, illustrate what social scientists might regard as typical population-related feedback. Congestion grows in a city; it becomes impossible to avoid Madonna indoors; people move; the city becomes less congested. Or, perhaps, the city enforces noise ordinances. In either case the problem is resolved after temporary conflict.

"Temporary" -- note the hedge word. The window of my old office looked out over the remains of the West Side Highway, part of which was closed as unsafe in the 1970s. I began using the office after a lengthy squabble had broken out over the best way to repair the road. Some wanted to do the job cheaply, shifting the money to mass transit; others said that the city needed the highway to revitalize its waterfront. Politicians, environmentalists, neighborhood groups, and construction unions attacked one another. Reconstructing the West Side Highway became a legal imbroglio of dizzying complexity. Charges and countercharges, suits and counter-quits -- I couldn't begin to follow it. Meanwhile, huge rush-hour lines built up twice a day on the partially closed road. Not wanting to sit in traffic, people took the exit near my office and continued their journeys on my street. They've been doing that in one form or another for more than a decade -- which is part of the reason there was so much congestion on the street, and part of the reason Madonna was in my office for so long.

Move to the country, buy extra-thick insulated windows -- middle-class Americans like me are unlikely to face the extreme choices that will confront people in developing nations. As Meadows says, we will be able to buy our way out of some problems. But that does not mean that Americans will escape the repercussions of population growth. In 1990 the United States had 249 million inhabitants. Current Census Bureau projections foresee that births and immigration will drive that number to 345 million by 2030. Ninety-six million more Americans! Imagine everything that local, state, and federal governments will have to do to accommodate them. Think of all the thoughtful planning that will be required to make life pleasant. Whether it will happen "is an absolutely open question, in my judgment," says Allen Kelley, an economist at Duke University. "We're talking about political theory, and there just is no theory for this."

The future is not completely opaque. Demographers know roughly where those 96 million new Americans will live, who they will be, and what they will do. The Census Bureau projects that the extra people will not distribute themselves in an even blanket over the country. About half will choose to live in just three states: California, Texas, and Florida. Not one of these can absorb its share easily. California has too little water, Texas an unsteady economy, Florida a particularly troubled set of ecosystems. All three will also need many new roads, bridges, sewers, and schools -- an expensive proposition.

Relatively few of the newcomers will be white. By 2030 about 40 percent of Americans will have ancestral roots in Africa, Asia, or Latin America. Few would disagree that people of color have long been at the bottom of the American pyramid. If that continues, many of the 96 million will be poor, and in the twenty-first century a bigger percentage of the U.S. population will be below the poverty level than is now. If that does not continue, white Americans will for the first time face nonwhite power centers. California, Texas, and Florida will have three of the four biggest voting blocs in the House of Representatives (the fourth will be New York's). All three could be dominated by Hispanics and African-Americans. If history is any guide, either alternative will put white Americans' moral grace sorely to the test.

The United States has a long border with Mexico, and thousands of miles of coastline. Migrants want to come in, and Americans seem increasingly diffident about putting out the welcome mat. (In 1991 Argentina's president publicly toyed with the idea of resettling skilled refugees at a price of about $50,000 a head.) Meanwhile, rising numbers will thrust together the blacks, whites, yellows, browns, and reds who are already here in ways they have not been before. Political turmoil is increasing in Europe -- especially in France and Germany -- as migrants from Africa, the Middle East, and the former Soviet bloc demand a piece of the better life. Population growth did not cause ethnic conflicts, but it could sharpen them.

At the same time, the United States will have to address its age shift. Census Bureau projections tell a sobering story. By 2030, one out of five Americans will be sixty-five or older. The ratio of elderly people to people of working age will have tripled since 1950, meaning that, on average, workers will have to support three times as many older people. (The figure may be offset somewhat by the smaller number of children there will be to support. But the problem will be amplified by the growing number of people in their sixties and seventies who will be taking care of still more elderly people, in their eighties and nineties.) Workers, meanwhile, will be facing gloomier prospects. Nowadays fewer older people are alive than younger people, which means that there is an approximate match between the small number of older workers and the small number of important jobs. As the population ages, this will change. "In a stationary population," Ansley Coale, the Princeton demographer, has written, "there would no longer be a reasonable expectation of advancement as a person moves through life." More and more people will find themselves trapped in dead-end jobs. In some ways, Coale suggests, we may end up looking back with envy at the days of rapid population growth.

People will have to deal with the frustration -- at the same time that they seek politicians able to resolve all the other problems. An optimist can say that the American people are kind, clever, and adaptable. An optimist can say that Americans can resolve the difficulties described, and the others these will inspire. But even an optimist must conclude that the government will have its hands full, and might well wonder what it will be like to live in a future America that must balance so much so artfully. My guess is that it will be something like living in New York City today.

Because I had nothing else to do, I walked along the last remaining section of the West Side Highway one recent Friday afternoon -- a masochistic act. The road is officially under construction, and so its shoulders have not been cleaned up. Heaps of trash lie in windblown aggregations. The walls are gray and peeling. Cars move slowly and impatiently, in billows of exhaust. It is like an evocation of an unpleasant future. New York City took a hit in the recession, and the familiar assortment of urban evils got worse. Unemployment and crack use went up; real estate values, tax revenues, and bond ratings went down. The city fabric sprang a hundred big leaks. Like so many Dutch boys, the city fathers raced to plug them. Meanwhile, a thousand interest groups scrabbled to protect themselves. Understandably, fixing the highway seems not to have assumed pressing importance.

That day on the West Side Highway, I heard many radios played at high volume. I could see the point. License plates came from Connecticut, New Jersey, and Pennsylvania; drivers were commuting for hours to sit in traffic. Only part of their daily grind was due to the sheer size of New York; traffic jams afflict much smaller cities. But a three-hour commute is what some architects call a "disamenity." The waiting, the ugly walls, the blaring horns, the inability to get away from it all: these are the disamenities of overpopulation in rich societies. None is directly attributable to population growth. Each is an emblem of bureaucratic overload -- overload caused by the hundred predicaments that population growth aggravates. The city could have fixed the West Side Highway long ago. So could the state, or the federal government. But they didn't. There are too many other, bigger concerns, and there will be for a long time. My Madonna problem is not going to vanish.

Population growth forces nations to confront problems that they could finesse in less crowded times. The inefficiencies of New York's highways surely mattered less when the metropolitan area held eight million people rather than fifteen. Governments may, as economists hope, avoid the major, life-threatening disasters. "Even Congress isn't stupid enough to avoid dealing with the ozone layer," one economist told me. Americans may create a society that can hold an older, darker-colored population. But while they are doing that, the disamenities accrue, making the future a grayer, grimier place. Per capita GNP may go up and up, but life will be less pleasant. How much less pleasant? The answer depends on the strength of the citizenry's desire to have a government that works much more flexibly and wisely than government does now. New Yorkers to date have shown little such inclination.

Down by Wall Street the West Side Highway has been demolished. The reconstructed roadway passes a few blocks to the west of the building where I saw those people on the gurneys. My guess is that most of its inhabitants -- the real ones, I mean -- have moved on. More have moved in, though. We're marching into the future together. Curtains are visible from the highway. There's some lawn furniture on the roof. It makes me wonder who owns it, and what they do, and whether, like me, they have children.

The online version of this article appears in two parts. Click here to go to part one.

Copyright © 1993 by Charles C. Mann. All rights reserved.
The Atlantic Monthly; February 1993; How Many Is Too Many; Volume 271, No. 2; pages 47 - 67.

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