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Nicholas Eberstadt holds
the Wendt Chair in Political Economy at the American Enterprise Institute. This
essay is adapted from a forthcoming chapter in Earth Report 2000, edited
by Ronald Bailey.
The year 2000 will conclude a
century of utterly unprecedented population change—an abrupt, dramatic
departure from previous experience. Yet
it is likely that developments in the 21st century will unfold in
ways that surprise even battle-tested demographers who think they are beyond
surprise.
Although
exact global numbers can never be known, population counters generally believe
that the number of humans on the planet exceeded 6 billion sometime in 1999,
and will total about 6.08 billion by the middle of this year. Data for the year
1900 are naturally even less precise, but a reasonable guess for the total
population in that year is around 1.65 billion. Thus in a century, world
population almost quadrupled in the process of adding almost four and a half
billion souls. No previous population
boom comes even close, either in percentage terms or absolute numbers.
By historical yardsticks, moreover,
the population explosion continues. The two premier demographic agencies -- US
Census Bureau and the UN Population Division -- both project a rate of increase
of 1.3 percent this year. That is over
twice the average rate in the 19th century and something like four
times the pace across the entire millennium. The total population is increasing
by almost 80 million persons a year-- perhaps ten times the average annual
number in the 19th century.
Yet paradoxically, the trend appears
to have reached a monumental turning point.
For as the 21st century commences, the tempo of population
growth is unmistakably in decline.
As rapid as the current rate of
natural increase appears against the backdrop of history, it is nonetheless
considerably slower than in the immediate past. In the early 1960s, for example, the pace exceeded 2.2 percent
per year--a percentage point higher than the rate anticipated for the year
2000. The growth in absolute numbers apparently peaked at 85 million a year in
the late 1980s, and has since been declining gradually.
The Longevity Explosion
To
estimate population trends, it is necessary first to understand the forces that
in turn generated the explosive acceleration, the peak and the decline in world
population growth during this century.
The
population explosion was entirely the result of health improvements and
the expansion of life expectancy.
Between 1900 and 2000, life expectancy at birth at least doubled from
something like 30 years to 63 years. Indeed, all other things equal, that health
explosion would have resulted in an even greater growth of human numbers than
has actually been witnessed. Rough calculations suggest that the world's
population would be over fifty percent larger today if our century's recorded
revolution in longevity had unfolded in the absence of other demographic
changes.
Secular
Fertility Decline
The
world’s population currently totals about six billion rather than nine billion
because fertility patterns were also changing over the century. And of all the diverse changes in fertility
trends registered over the past hundred years, the most significant has been
"secular fertility decline"--that is to say, sustained and
progressive reductions in family size due to deliberate birth control.
In
historic terms, this trend is a very new phenomenon: it apparently had not
occurred in any human society until about two centuries ago. France, where the trend began by the early
19th century, was the first country to experience the sustained
decline. Since that beginning, the decline has spread steadily if unevenly
across the planet, embracing an ever rising fraction of the global population
and depressing voluntary childbearing in the affected societies to successive
record lows.
A
milestone in the process was passed during the era between the World Wars.
Fertility rates in industrialized countries during peacetime dropped below the
"net replacement" level-- below the level necessary for long-term
population stability.
The
inter-war fertility dips proved to be temporary, neither sufficiently prolonged
nor sufficiently deep to bring on actual population decline. But in the last quarter-century
sub-replacement fertility has come back with a vengeance, slipping to levels
previously unimaginable in prosperous societies at peace. Sub-replacement
fertility has now been experienced over a generation or more in a growing
number of countries, and it has come amazingly close to becoming the norm the
world over. Indeed, almost half of the
world's population lives in societies that aren’t having enough babies to
sustain their numbers.
In
the early 1950s, the planet-wide "total fertility rate" -- the
average number of children per woman per lifetime--is thought to have stood at
about five. Next year, the global TFR
will likely be below 2.8. That dramatic
reduction in four decades has already curbed the relative and absolute pace of
world population growth, in spite of increasing life expectancy. But even more
dramatic changes – changes never contemplated by Malthusians – lie ahead.
The
past generation demonstrated that it is possible for fertility levels to fall
with startling speed, even in low-income societies. And while we now know that countrywide fertility levels can
plunge well below replacement and remain there for decade after decade, we do
not yet know how low they can go. But it is entirely possible that, contrary
even to quite recent expectations, sub-replacement fertility will soon typify
the world as a whole. Were that to occur,
the 21st century could turn out to be a time in which world
population peaked and thereafter diminished.
The
population has fallen before—in the 14th century, for example. Those
earlier reductions, however, were the consequence of catastrophes: bubonic
plague decimated societies across Asia, Europe and North Africa between 1333
and 1355. The 21st century population implosion, by contrast, would
take place under conditions of steadily improving life expectancy and living
standards.
Even
so, such a de-population would confront the world with its own socio-economic
challenges —- quite possibly formidable ones.
Though negative population growth is not yet imagined to be a problem,
we must now recognize that it is possible that this, rather than Malthusian
over-population will emerge as the great demographic issue of the coming
century.
Fertility Trends At Century's End
Many
analysts do not appreciate just how far low-fertility regimens have already
progressed. To understand the current
situation, divide the world into three categories: (1) countries where
fertility levels are currently believed to be below replacement (2) countries
where fertility is above replacement but rapidly declining (3) countries where
fertility levels remain high and seemingly immune to secular fertility
declines.
1) Sub-replacement Fertility.Table 1 catalogues the countries in this first category. Since the
numbers are extrapolations based on recent history, they may exaggerate the
dimensions of fertility decline. On the other hand, the population data for
most places listed here is both relatively up-to-date and reasonably accurate.
So it is equally the numbers understate the trend. Indeed, this list, based on
Census Bureau estimates, is more conservative than the UN Population Division's
figures.
In
all, 79 countries and territories, with 44 percent of the world’s population,
fit the below-replacement category. And the countries themselves are strikingly
diverse in geography, culture and level of economic development.
Virtually
every advanced industrial democracy is on the list. In fact, 27 of the Organization for Economic Cooperation and
Development’s 29 members have total fertility rates of less than 2.1 —- more or
less the level required for long-term population replacement. The two
exceptions, by the way, are Mexico and Turkey, countries at the low end of the
OECD as measured by income and education.
Within the regular OECD grouping, the highest total fertility rates are
the United States (2.07) and Iceland (2.04)--levels just shy of replacement. At
the other end, Germany and Spain's current TFRs are just over 1.2 -- and
Italy's is even lower.
Most
OECD members are in Western Europe, which had a collective TFR of 1.4 in
1998. But overall fertility levels
appear to be even lower in Eastern Europe--by Census Bureau reckoning, about
1.3. Bulgaria, in fact, has the lowest
fertility level ever witnessed in modern nation not at war, with women
averaging only 1.14 births in a lifetime. Were that pattern maintained
indefinitely, each new generation would be half the size of the one
before. In all of Europe, only remote
Albania and the tiny outposts of Gibraltar and the Faeroe Islands are thought
to be above-replacement enclaves--and in those cases, only barely so.
Within
the former USSR, fertility has fallen far below replacement since the collapse
of the Soviet empire. While fertility
rates in the six former Islamic Soviet republics all appear to be above the net
replacement level (from Kazakhstan's projected TFR of 2.1 to Tajikistan's 3.5),
the other nine states are far below replacement. In the Russian Federation, by far the most populous of the former
Soviet republics, fertility is a shade over 1.3. In the next largest, Ukraine, the TFR is just over 1.3--as it is
in Belarus and in the three Baltic states. With a projected TFR of 1.88,
Moldova would rank as distinctly the most fertile European enclave within the
former USSR today.
Secular
fertility decline, as already noted, originated in Europe. And today, virtually
every population group in the world of European origin has a fertility rate
below replacement. But these account for only about a billion of the 2-1/2
billion people living in sub-replacement regions. Below-replacement fertility
thus is no longer an exclusively European – or even predominantly European
phenomenon.
Much
of the Caribbean is now bearing children at below the replacement rate. Island
societies as culturally and economically diverse as Barbados, Cuba and
Guadeloupe have fertility rates below that of the United States. A few tiny territories off the coast of
Africa and in Micronesia have apparently also slipped into the sub-replacement
category. But the largest concentration
of sub-replacement populations is in East Asia.
Japan was the first non-European
society to report sub-replacement fertility in peacetime. The rate fell below
replacement in the late 1950s and has remained there for the past four decades.
The U.S. Census Bureau puts Japan's TFR at 1.46 –- and Japanese authorities say
it is even lower.
All
four East Asian tigers -- Hong Kong, South Korea, Singapore and Taiwan -- have
been below replacement fertility since the early 1980s. South Korea has the
highest fertility level of that group, with a TFR estimated at just under 1.8;
Hong Kong, with a TFR of 1.36, is lowest.
Thailand's fertility rate also fell below replacement in the last
decade; its current estimated TFR is a bit over 1.8.
By
far the largest sub-replacement population, though, is China's: total fertility
on the mainland dropped below net replacement in the early 1990s and was
thought to be 1.8 for 1998. China's fertility, of course, has been affected by
Beijing's two decades-old population control campaign. It is only reasonable to suppose that the
Chinese State Family Planning Commission's strident and muscular intervention
in the name of a "One Child Norm" has had an impact. But it is not possible to say how great that
impact has been--or what would happen if that program were abandoned.
2) Above-replacement, but Rapidly Declining,
Fertility. Another large portion of
humanity lives in countries where fertility is still above the net replacement
level, but is declining rapidly. Just how large a fraction of humanity this
grouping encompasses, of course, depends upon one's definition of
"rapid."
According
to the UN Population Division's most recent estimates, total fertility rates
for "less developed regions" dropped by half between the late 1960s
and the late 1990s, from an average of six births per woman per lifetime down
to three. Of course, those averages were strongly affected by the trend in
China, and China's circumstances were anomalous. But the Chinese experience should not divert attention from the
breadth and scale of fertility declines in other low-income settings.
Table
2 presents UN Population Division estimates of fertility change between the
late 1960s and the late 1990s in the fifteen most populous developing countries
-- home to three-quarters of the population of the less-developed regions. During those three decades, fertility levels
fell by over half in seven of the 15 -- which is to say, in five countries
besides China and Thailand. Two of
those five (Brazil and Mexico) are traditional Catholic societies, while the
other three (Bangladesh, Iran and Turkey) are Islamic.
Note
that 12 of the 15 countries in Table 2 experienced fertility declines of
two-fifths or more while, in absolute terms, 10 of the 15 registered TFR
declines of over three births per woman!
Only one of the fifteen (Ethiopia) has yet to reduce fertility
significantly. Note, too, that in spite of the religion-based pro-natal
traditions of Mexico and Iran, fertility has dropped by four births per woman
in just 30 years.
Table
2 underscores a more general feature of the fertility decline process now
underway in low-income countries: there is no single obvious cause. We think of
fertility as being inversely associated with living standards, and in a very
general way it is. Yet one of the world’s poorest countries, Vietnam, has a
fertility level in the same range as the United States of the Vietnam War era.
The rate of income growth is an equally problematic indicator of fertility
decline. For while Indonesia's dramatic fertility reductions coincided with
relatively rapid GDP growth, per capita GDP actually shrank in Iran over those
same years--and yet Iran's fertility declines were even steeper than
Indonesia's.
We
often hear that education, particularly female education, has a big influence
on fertility. But Table 2 shows no
clearcut international pattern.
According to the World Bank Nigeria's 1995 adult literacy rate was
higher than Egypt's--but its current TFR is also higher, and by almost two
births per woman. Conversely, the World
Bank estimates that adult literacy is currently 50 percentage points lower in
Bangladesh than in the Philippines, and the gap between male and female
literacy rates is closer to 70 percentage points. Yet fertility is lower in
Bangladesh than the Philippines, and Bangladeshi fertility declines over the
past three decades have been distinctly greater in magnitude.
What
about family planning? It has become a
matter of faith that government population control initiatives have been
instrumental, if not indispensable, in fertility decline in low-income
settings. And it is true that most of
the developing countries reporting major fertility declines in recent decades
did have national birth control programs in place -- some of which were overtly
coercive. But even though Brazil has never sponsored family planning, its
fertility decline in percentage terms has been almost identical to Mexico's,
where a strong national program operates. And although Brazil is both poorer
and more poorly educated than Mexico, its fertility level is lower as well.
It
is all too clear, then, that the standard socioeconomic predictors of fertility
differences are of distinctly limited utility. Indeed, one is tempted to
conclude that the strongest predictor of a country’s fertility level is the
calendar: the later the date, the lower the fertility level.
3) High and "Resistant" Fertility. The third share of humanity lives in
countries where TFRs are very high --say, six or more -- and for whom
convincing evidence of fertility decline has yet to be reported.
People
often assume that such countries typify the developing regions. But since fertility levels in the less
developed regions as a whole are thought to have fallen by half over the past
thirty years, this clearly cannot be the case.
In the entire Asian land mass, TFRs were down by half between the late
1960s and the late 1990s, from about 5.7 to 2.8. In Latin America and the Caribbean, TFRs have fallen from roughly
5.6 to 2.7.
The
regions where fertility remains highest (and where fertility declines have been
most modest) are sub-Saharan Africa and the Islamic expanse to its north and
east--more specifically, the Arab Middle East. These areas had a population of
about 930 million in 1998 -- a little less than a fifth of the total for less
developed regions, and a bit under a sixth of the world total.
Fertility
levels are much higher within this agglomeration than in any other comparably
sized group of nations. However, the image of uniformly high, persistently
"traditional" fertility regimens is already badly outdated. A revolution in family formation patterns
has begun in the region.
Table
3 suggests that it is no longer accurate to describe the "Arab world"
as a place isolated from fertility decline.
Over the past thirty years, in fact, fertility in "Northern
Africa"--the territory stretching from Western Sahara to Egypt--is
believed to have dropped by almost half, to an average of 3.3 births per
woman. There are still outposts of
awesomely high and nearly unyielding fertility: the Gaza Strip (with a TFR of
7.3), Oman (5.9), Saudi Arabia (5.8) and Yemen (7.6). But these four places account for barely 40 million of the Arab
Middle East's quarter of a billion people.
Elsewhere relatively rapid fertility decline is underway, and in some
Arab countries the decline is rapid. In
Algeria, Libya, and Morocco and Syria, TFRs have dropped by nearly half in just
the past two decades. And there are
now Arab countries – notably Tunisia and Lebanon -- where fertility levels are
falling close to the net-replacement level.
Even
less generally appreciated than the fertility reductions throughout the Arab
world is the fact that fertility decline appears to be underway in parts of
sub-Saharan Africa too. Particularly noteworthy is the recent Kenyan
experience: over the past two decades, the country's TFR fell by two-fifths, to
an average of 3.7 births per woman.
Kenya
speaks to another aspect of fertility decline in low-income countries worth
bearing in mind: the long lag between its onset and the moment demographers can
assay its magnitude. Like all sub-Saharan countries, Kenya lacks reliable vital
statistics. Its population trends must therefore be divined from occasional
censuses and episodic surveys.
Kenya
collects more demographic information than most. Even so, the pace of the
country's recent fertility declines has surprised the experts. In 1994, the UN
Population Division's very lowest projection for Kenya for the early 1990s was
a TFR of 6.2. In fact, the TFR was 5.4--or by almost one birth per woman lower
than the lowest contemporaneous UN projections had imagined. By the same token,
contemporaneous fertility estimates for some other sub-Saharan locales may be
way off base.
What Happens Next?
Barring
utter cataclysm, population trends in the next century will be dominated –
indeed, determined -- by trends in fertility. That’s just a matter of
arithmetic as long as death rates remain low and stable. But what course will
world fertility trends take?
There
is no way for predicting with much certainty. The UN Population Division's
Expert Group Meeting on Below Replacement Fertility summarized the state of
knowledge succinctly: "There exists no compelling and quantifiable theory
of reproductive behavior in low fertility societies." The same might be
said about reproductive behavior in contemporary societies with higher levels
of fertility. As a practical matter,
fertility prediction is a matter of educated guesswork.
Some
eminent demographers, notably Charles Westoff, have advanced a
"homeostatic" hypothesis suggesting that sub-replacement fertility
rates will be drawn upward to replacement as if by "a magnetic
force." But that is pure speculation.
By the same token, demographers including Antonio Golini have recently
suggested that TFRs in stable industrial societies are unlikely to dip below
0.7 -- the level already observed in eastern Germany after unification. The discomfiting reality is that today's
sub-replacement fertility patterns are terra incognita--and that
demographers don’t even have much to say about what happens once a population
enters it.
The
situation is not much more certain for countries still above the replacement
rate. The demographer Dudley Kirk has argued that "no country has been
modernized without going through the demographic transition [that leads to both
low levels of mortality and fertility]." But the definition of
"modernization" must now be sufficiently elastic to stretch around
cases like Bangladesh and Iran--countries where low average incomes, high
incidences of extreme poverty, slow economic growth, mass illiteracy, high
levels of mortality and other ostensibly "non-modern" characteristics
have proved compatible with massive voluntary reductions in fertility.
We
now know, moreover, that fertility decline can kick in swiftly in low-income
settings. As Table 4 attests, there are now examples of countries in which
fertility levels have declined by 1.5 births per woman per decade for a full
quarter of a century. In sub-Saharan Africa total fertility has
been falling by 20 percent per decade, while in Latin America and the Middle
East the pace is around 30 percent per decade. The comparable figure for East
Asia is nearly 40 percent, thus far sustained for two and a half decades.
Forget
theory. It is a fact that fertility levels have fallen by three-fifths in just
twenty-five years in one Arab country (Tunisia) where upwards of half of all
women of childbearing ages have had no formal schooling, and by 45 percent in a
sub-Saharan country (Kenya) with a dismal incidence of poverty. For whatever
reasons, the constraints against fertility decline appear to be receding
remarkably in our own time—and may possibly continue to recede in the coming
century.
The
UN’s “medium variant” fertility projections envisions a world thirty years
hence with an overall TFR of 2.23 -- 1.75 in "more developed regions"
and 2.31 in the "less developed regions." That would mean a global
population of 7.8 billion in 2025 and 8.9 billion in 2050.
While
the die seems to be cast for the advanced industrial countries, it is easy to
imagine factors that significantly raised the pace of population growth above
the medium variant elsewhere. For example, a slower than expected fertility
decline in the Indian sub-continent. Or a later-than-postulated advent of
fertility decline in sub-Saharan Africa. Or the resumption of above-replacement
fertility in China. But it is also possible to imagine alternatives that lead
to a cessation of population growth and a subsequent depopulation, despite
assumed steady improvements in life expectancy.
One Scenario for Global De-population
The
UN Population Division's "low variant" population projections, in
fact, offer just such a vision. In this scenario, global life expectancies--and
life expectancies in every region of the world--rise steadily over the first
half of the century. But population
crests in 2040 at 7.47 billion (growing by about 25%, or about a billion and a
half people, between now and then), drops by about 120 million between 2040 and
2050, and then continues to decline by over 25 percent per generation.
Of
course, assumptions about fertility drive this model. The "low variant" scenario imagines net-replacement
fertility for the world as a whole by the years 2000-2005 —- that is to say,
more or less now -- and sub-replacement fertility thereafter. We must therefore ask whether such
presumptions are plausible.
One
way of assessing these projections is to compare them to the recent historical
past. Table 5 examines the "low variant" model's assumed fertility
declines for the three decades between the early 1990s and the early 2020s and
compares them with the actually recorded declines over the three previous
decades.
For
every area of the world, these "low variant" projections imagine
vastly lower fertility levels by the early 2020s than ever before recorded.
Some may regard that in itself as a sign of inherent implausibility. But looked
at a bit differently, the low variant projections simply suggest a continuation
of already existing trends--and in fact, a slight deceleration from the pace of
decline between the early 1960s and the early 1990s.
The
only region of the world for which the low variant projections imply a faster
fertility decline is the African continent. Here, fertility would have to fall
as rapidly in absolute terms in the coming decades as it did in Asia from the
early 1960s through the early 1990s. That likelihood is, of course, debatable.
But in light of the Asian and Latin American experiences, one can hardly
maintain that the low variant projections for Africa are out of the realm of
possibility. And the assumptions
embodied in the scenario projecting a peaking, and subsequent decline, in
global population in the coming century do not seem especially heroic.
Population Issues For A Depopulating World
If
the pace of global fertility decline continues for another generation--and the
world consequently heads toward negative population growth--the population
issues of the future won’t resemble those of the recent past. In a world of
long life expectancies, small families and negative population growth, the
Malthusian specter will cease to be relevant to public policy. On the other hand, pervasive and prolonged
sub-replacement fertility in the context of generally improving health would
likely pose social, political and economic challenges of its own. Rising
life expectancy guarantees that the world's population will be aging in the
coming century. If fertility is low and falling, it will age all the more
rapidly. At the moment, the median age
of the world's population is about 26 years.
If the trajectory anticipated by the current UN low variant projections
were to come to pass, this figure would rise to 44 years --higher than those
for even the “elderly" populations like Japan in our contemporary world.
Rapid
global aging would have a number of ineluctable implications. For one thing, it would increase the
salience of addressing the health care and income security needs of the
elderly. In Western countries, current
public programs for these purposes are coming under increasing demographic
pressure, and require far-reaching overhauls to maintain financial soundness.
In low-income countries, where coverage by public pension and health systems is
limited, the issue of how to take care of the elderly could be all the more
pressing.
Rapid
global aging would also likely beg the question of how to educate and train the
work force of the future. It is not difficult to imagine circumstances in which
a majority of a country's workers were over the age of 50. And such a scenario would exacerbate the
already existing tensions between an educational system designed to train the
young and the desire of workers to enjoy long, worthwhile careers in an
increasingly complex economy.
Finally,
prolonged sub-replacement fertility in a world of long life expectancy would
presage a radical change in family structure along the lines of one-child
China. For the first time in the human experience, there could be societies in
which the only biological relatives for many people would be their
ancestors. With sufficiently low
fertility for just two generations, people with blood siblings and cousins
would become the exception. Exactly how a society would operate under such
conditions – how, for example, children would be socialized -- is difficult to
imagine.
All
this is merely constrained speculation. But if it does indeed turn out that
today’s sub-replacement fertility societies are only a foretaste of what lies
in store, such speculation is hardly an indulgence. Long-term population decline under conditions of steady health
improvement is not a disastrous demographic portent—any more than was the Twentieth
Century’s dual explosions of population and health. But an orderly global
depopulation would require strange new adjustments—some of them
wrenching—in both economies and societies, and we are more likely to cope with
these changes successfully if we have contemplated them in advance. |
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