The belief in an ever-increasing world population has been one of the fundamental ideas of this generation—like our small place in the universe and our biological links to animals. Recent developments, however, have undermined the facts on which that belief was based. The last twenty years have built a mountain of evidence that the world’s human population will stop growing within the lifetime of many people now living. The human race is not breeding to extinction, like lemmings; we should expect to move into a long period of declining population.
World population began to grow rapidly shortly before the last century and accelerated in this one. It was less than 1 billion in 1800 and 1.6 billion in 1900, and will be almost 6 billion at the end of this century. The fastest growth was in the 1960s, a little more than 2 percent per year. And although the rate has been slowing for more than thirty years, it is still well over 1 percent per year.
Nonetheless, we can be confident that within fifty years or so the world’s human population will start declining. The reason: population trends have great momentum. The number of births this year reflects changes many years in the past, and what has been happening in recent years will have effects far into the future. In the short run, the growth of a population depends on its average age. A young population—where there are many more people 0-20 than 20-40 years old—will grow because the current children will grow up and their generation will have more children than their mothers’ did, even if each daughter has fewer children than her mother.
Long-run growth, however, depends on fertility, which is measured by the number of children the average woman bears in her lifetime. A population can grow only for a limited time if the average woman fails to replace herself and her husband, by having fewer than 2.1 children. During the first half of the 1990s, world fertility was 3.0, but it has been falling increasingly quickly for the last forty years. Some 44 percent of the world’s population live in countries where the fertility rate is already below replacement level. Current trends will bring world fertility below that level within the next twenty years or so.
This trend first appeared in France in the eighteenth century and has become universal except for a few countries in Africa. American women began having fewer children well over a hundred years ago, and that decline in fertility has continued ever since, apart from a twenty-year blip after WWII. Between the early 1970s and the early 1990s, fertility in Asia, Latin America, the Caribbean, and North Africa, where most people live, fell from over five children to under three—in only twenty years! Unless these fertility declines are brought to a screeching halt by something that has not appeared on the horizon, they will produce a decline in world population.
Predictions of future population have often been wildly wrong, because they are usually based on current and recent “birth rates.” Birth rates, which measure births in a single year, fluctuate greatly, but fertility trends from one age cohort to the next are much more stable. And major changes in direction of long-term fertility are rare. The temporary increase in fertility of U.S. women born in 1927-1947, which produced our postwar baby boom, is the largest divergence ever. But the fertility of American women returned to the old trend line and is well below replacement level.
Fertility responds to many influences—economic, social, intellectual, and spiritual—and analysts cannot explain past fertility through any formula based on a small number of variables such as per capita GDP or per cent of female literacy. Thus although we can never be quite certain about future fertility rates, we can have much confidence about the overall patterns. Declining fertility correlates with high survival rates for children, increased education for women, reduced value of children’s work, increased costs of child-raising, and the customs and attitudes that respond to these changes. These factors are all built into and inseparable from modern society.
As modernization spreads, sharply falling fertility has been observed in Western and Eastern societies; in Catholic, Moslem, secular, and Buddhist countries; with black, white, and yellow people; and with Swedes and Italians. Clearly the trend is neither superficial nor easily changeable.
Until recently, the impact of declining fertility has been masked by other trends—fewer deaths, more total births—and by the fact that seriously falling world population is still many years away. Most importantly, until fairly recently it was assumed that fertility would decline only until it reached replacement rate, and would then remain fairly stable.
Thus total population was expected to rise and then become stable, with people everywhere eventually matching birth and death rates—as in a mature forest. But in country after country this expectation has proven false. Fertility has continued to fall as fast after reaching replacement rate as it did before. In no country has it stopped at replacement level. The U.S. is one of more than fifty countries where fertility is already at or below replacement level. In Italy, Portugal, and Greece, for example, fertility has declined to approximately 1.2 children per woman. But in most other countries, even those where fertility began to fall much sooner, it has not fallen below 1.5.
In “non-Western” and less-developed countries the pattern is the same. In most countries—such as Kenya and Bangladesh—where fertility is still above replacement level, it has been decreasing for at least ten to fifty years and is declining faster than it did in most advanced countries. The statistics all suggest that fertility in such countries will fall to Western-nation levels.
Thus it would take a drastic—almost miraculous—change to prevent world fertility from falling below replacement level in the next few decades and total population from beginning to fall a few decades later.
Using assumptions consistent with recent experience, demographers estimate that world population will reach its peak somewhere near the middle of the next century—probably 25 to 50 percent higher than today. Then the decline will begin. The best “neutral” estimate from past experience is that world population will begin falling about a half-century from now, after rising to approximately eight billion, and will fall to less than half that number before it stops. Of course, it is impossible to be sure about the future, but there is no analytic or experiential basis for thinking that that world population will continue to rise for another century or above ten billion people.
What is coming is not just a nominal or technical decline but major reductions in the world’s human population. There is every reason to expect long-term world fertility rates to be in the range of 1.2 to 2.0. Intermediate plausible fertility rates—such as 1.4 and 1.8—would produce annual reductions of approximately 1 percent or .5 percent, which would mean that during a single lifetime, world population would fall by one-third to more than one-half. In a few centuries such fertility rates would reduce world population by more than three-quarters.
So far there has been no demonstration that in modern conditions fertility can rise above the replacement rate for any long time. France and other European countries have made a variety of efforts to increase fertility, with disappointing results. If values change enough to alter the current fertility pattern, future world population will become a wild unknown. Otherwise we can count on it to decrease considerably.
We can note one piece of good news and an item of bad news about a world of steadily declining population. The good news is that although the population will be much older than today, the financial problems of the elderly need not be an excessive burden on the working population. The increase in elderly people will be matched by a fall in the proportion of people too young to work, and people will be productive well beyond what is now taken as the magic limit of sixty-five. The bad news, as Nicholas Eberstadt has noted, is that where one-child families are standard, few people will have brothers, sisters, cousins, aunts, and uncles, and most people will have only one grandchild.
The gradual spread of declining population around the world will influence policy in two ways. First, the prospect—and then the reality—of a decreasing world population will change our perception of the world. Second, European countries will attempt to prevent or mitigate the effects of national population decline. Also, the transition to the long-term distribution of population around the world, which is likely to be very different from the current distribution, may assume importance.
If people were strictly rational, the prospect of world population decline would have little effect. Individuals and countries are hardly affected by the current level of world population, much less future levels. No serious quantitative argument can be made that the Earth cannot safely feed and dispose of the garbage of twelve billion people for thousands of years. Thus the “news” that we should expect a peak population of approximately eight billion instead of ten to twelve billion, and thereafter a long decline instead of a constant level, should not change anyone’s views about the prospects for obtaining the raw materials we need and for protecting the environment. With either size population the question would be how to solve these problems, not whether we could.
Even so, I believe that the essence of radical environmentalism’s ability to generate mass support is the widespread fear of a worldwide population explosion. When that fear is shown to be groundless, the thirty-year perception of “environmental crisis” may finally come to an end. “A declining population soon” is much more inspiring than “a level population later.” Thus we can hope that environmentalism will no longer be seen as a desperate crusade but instead a permanent task that requires us to weigh alternative approaches and competing concerns—rather than a simple “you can’t be too safe” issue with all the “good guys” on one side.
The hard question is, if environmentalism is now filling the need for secular transcendence that socialism, communism, and other utopian programs used to fill, what will happen if a falling world population takes the charisma out of it (making it just a practical task, like cleanliness)? Will the intellectuals find a new and worse opiate? It is hard to believe that a supply will not be found to meet the demand for a new “cause.” Compared to most such causes, environmentalism has been relatively harmless. Perhaps we would be better off if it kept its extremist vigor, despite the costs.
The immediate issues are more mundane. Japan and almost all of Western Europe already have more deaths than births, and their populations are getting older. This presents two concerns: a shortage of young people to provide less-expensive, less-skilled labor (not to mention enthusiasm and social spice), and a smaller nation. Of course a “shortage” of young people has other psychological and social effects—some good, some bad. There is no relevant experience with societies where the numbers of old and young were equal, and it is perhaps the prejudice of my age to think that it might be an improvement.
No decisive economic disasters necessarily follow from such an age pattern. Although such a population may not generate as much vitality as we are used to, it need not produce recessions, deflation, or poor economic growth. There is no apparent reason why a country cannot continue to be prosperous while becoming smaller. Note that although some kinds of demand will decline, so will some costs. Population reduction and aging happen slowly enough to allow societies time to adjust. Of course, the fact that relatively painless changes can be made does not ensure that they will be made. In some countries, there may be major economic mismanagement in response to demographic change.
Nationalism is the main reason some countries will want to avoid a population decrease. Of course, people will give reasons other than national pride, such as various economic arguments. But France, for example, just might not want to be half the size of Italy or England—although it need not be afraid of being conquered any more than Luxembourg and Denmark are today. The big European countries might not want to get smaller even if they all declined at the same rate, fearing that Europe would become a less significant part of the world—although this too should not be a security fear.
European countries can manage the shortage of young workers—and of people to do service and less-skilled work—by taking in temporary foreign workers, most of whom leave before having families. Each year fewer such workers would be needed because the older local population would continue shrinking. But temporary foreign workers do not stop a nation from shrinking. That requires immigrants, presumably people who come as young adults, become citizens, marry, and have children who remain. If a country such as France is losing 1 percent of its population per year because of an excess of deaths over births, it can prevent a population decline by accepting as potential citizens a cohort of young people equal to approximately 3 percent of its own youth population.
Thus the ratio of local to immigrant young people (aged, say eighteen to thirty-five) would always be approximately thirty to one. Some of these immigrants would marry other immigrants, others would marry French nationals. Although their children would be “less French,” their grandchildren would be French, and the population of France would be constant. (If necessary, other young people could be accepted temporarily to provide additional unskilled labor.) It seems unlikely that such a rate of immigration would have to make France much less French.
Thus any country that has even a modest ability to assimilate immigrants can probably maintain its size indefinitely if it is sufficiently richer or otherwise more attractive than some other countries. (Because of its traditional antagonism to foreigners, Japan may be the primary country that cannot use immigration to keep its population from falling.) For at least the next century or so, Western Europe should have little trouble finding sufficient immigrants, although each country will need to decide how to choose among potential newcomers.
Immigration, however, will probably create some difficult and divisive political problems. Countries will have to decide how they feel about various religious, racial, and other distinctions. Some countries may choose to shrink rather than accept enough immigrants to maintain their size. Others may take so many immigrants that they become larger.
Even if Western European countries do not increase immigration strictly to maintain their populations, there will be economic and other pressures to accept immigrants. For at least a century, much of the world will be poorer, more violent, and less free than Europe. Thus many people will want to move there, and even modest response to such pressures may maintain Western European population levels.
With its relatively small population, Europe can take as many immigrants as it needs without significantly affecting Asia and Africa. If Western Europe prefers immigrants from Eastern Europe, however, the latter will shrink considerably unless it accepts a larger number of non-European immigrants to compensate for both emigration and low fertility. I would guess that the population of Western Europe will be about the same at the end of the next century as at the beginning—despite an excess of deaths over births among the native population throughout the century. And if world population declines, Europe’s percentage would rise, perhaps exceeding its current level. The situation for Russia and Eastern Europe is rather different, as noted, because of possible outflows.
Although U.S. fertility has been a little below replacement level for twenty-five years, our population is still young enough to produce a natural increase of more than .5 percent per year, in addition to an immigration rate well above .25 per cent per year. Although our median age has already increased from twenty-eight in 1970 to nearly thirty-five today, our total population will probably top 350 million before it stops increasing. If immigration continues at the current rate, newcomers will comprise an increasing share of our growth and eventually all of it.
Sometime in the next century, the U.S. will probably begin to have more deaths than births, and therefore a falling population except for immigrants. For a variety of reasons, we will probably continue to accept enough immigrants so that our population continues to rise, even apart from any reluctance to have our population fall. Thus the U.S. is likely to comprise an increasing share of the world’s population. We now comprise approximately 4.5 percent (down from 6 percent in 1950). If immigration keeps our population rising while world population falls, by the end of the twenty-second century the U.S. might comprise 10 percent of the world’s population. In fact, the U.S. share might approach 10 percent in only one-hundred years (for example, U.S. grows .4 percent per year to five-hundred million, world declines .9 percent annually after 2050 to five billion).
The basic facts of life—birth and death—will reshape our perceptions of the world during the next several centuries as modernity spreads and the demographic transition is completed and followed by post-transitional patterns. The short-term effects will be a decline in fear of overpopulation and environmental catastrophe, a variety of complicated consequences of increased immigration to Europe, and social changes engendered by an aging population.
Although the prospect of a society with as many old as young people may be somewhat depressing, young people have been the source of much of the world’s tragedy. The skepticism and conservatism of a more mature population may provide valuable protection against the characteristic dangers of modern society: decadence and utopianism. On the other hand, the dearth of young people may combine with the near elimination of poverty, tyranny, and war to increase another problem: boredom.