For most of human history, the world\u2019s population grew so slowly that for
most people alive, it would have felt static. Between the year 1 and 1700,
the human population went from about 200 million to about 600 million; by
1800, it had barely hit one billion. Then, the population exploded, first in
the United Kingdom and the United States, next in much of the rest of Europe,
and eventually in Asia. By the late 1920s, it had hit two billion. It reached
three billion around 1960 and then four billion around 1975. It has nearly
doubled since then. There are now some 7.6 billion people living on the
planet.

Just as much of the world has come to see rapid population growth as normal
and expected, the trends are shifting again, this time into reverse. Most
parts of the world are witnessing sharp and sudden contractions in either
birthrates or absolute population. The only thing preventing the population
in many countries from shrinking more quickly is that death rates are also
falling, because people everywhere are living longer. These oscillations are
not easy for any society to manage. \u201cRapid population acceleration and
deceleration send shockwaves around the world wherever they occur and have
shaped history in ways that are rarely appreciated,\u201d the demographer Paul
Morland writes in The Human Tide, his new history of demographics. Morland
does not quite believe that demography is destiny, as the old adage
mistakenly attributed to the French philosopher Auguste Comte would have it.
Nor do Darrell Bricker and John Ibbitson, the authors of Empty Planet, a new
book on the rapidly shifting demographics of the twenty-first century. But
demographics are clearly part of destiny. If their role first in the rise of
the West and now in the rise of the rest has been underappreciated, the
potential consequences of plateauing and then shrinking populations in the
decades ahead are almost wholly ignored.\u00a0\n\nThe mismatch between expectations of a rapidly growing global population (and \nall the attendant effects on climate, capitalism, and geopolitics) and the
reality of both slowing growth rates and absolute contraction is so great
that it will pose a considerable threat in the decades ahead. Governments
worldwide have evolved to meet the challenge of managing more people, not
fewer and not older. Capitalism as a system is particularly vulnerable to a
world of less population expansion; a significant portion of the economic
growth that has driven capitalism over the past several centuries may have
been simply a derivative of more people and younger people consuming more
stuff. If the world ahead has fewer people, will there be any real economic
growth? We are not only unprepared to answer that question; we are not even
starting to ask it.

At the heart of The Human Tide and Empty Planet, as well as demography in
general, is the odd yet compelling work of the eighteenth-century British
scholar Thomas Malthus. Malthus\u2019 1798 Essay on the Principle of Population
argued that growing numbers of people were a looming threat to social and
political stability. He was convinced that humans were destined to produce
more people than the world could feed, dooming most of society to suffer from
food scarcity while the very rich made sure their needs were met. In
Malthus dire view, that would lead to starvation, privation, and war,
which would eventually lead to population contraction, and then the
depressing cycle would begin again.

Yet just as Malthus reached his conclusions, the world changed. Increased
crop yields, improvements in sanitation, and accelerated urbanization led not
to an endless cycle of impoverishment and contraction but to an explosion of
global population in the nineteenth century. Morland provides a rigorous and
detailed account of how, in the nineteenth century, global population reached
its breakout from millennia of prior human history, during which the
population had been stagnant, contracting, or inching forward. He starts with
the observation that the population begins to grow rapidly when infant
mortality declines. Eventually, fertility falls in response to lower infant
mortality but there is a considerable lag, which explains why societies in
the modern world can experience such sharp and extreme surges in population.
In other words, while infant mortality is high, women tend to give birth to
many children, expecting at least some of them to die before reaching
maturity. When infant mortality begins to drop, it takes several generations
before fertility does, too. So a woman who gives birth to six children
suddenly has six children who survive to adulthood instead of, say, three.
Her daughters might also have six children each before the next generation of
women adjusts, deciding to have smaller families.

The burgeoning of global population in the past two centuries followed almost
precisely the patterns of industrialization, modernization, and, crucially,
urbanization. It started in the United Kingdom at the end of the nineteenth
century (hence the concerns of Malthus), before spreading to the United
States and then France and Germany. The trend next hit Japan, India, and
China and made its way to Latin America. It finally arrived in sub-Saharan
Africa, which has seen its population surge thanks to improvements in
medicine and sanitation but has not yet enjoyed the full fruits of
industrialization and a rapidly growing middle class.

With the population explosion came a new wave of Malthusian fears, epitomized
by the 1968 book The Population Bomb, by Paul Ehrlich, a biologist at
Stanford University. Ehrlich argued that plummeting death rates had created
an untenable situation of too many people who could not be fed or housed.
The battle to feed all of humanity is over, he wrote. In the
1970the world will undergo famines hundreds of millions of people are
going to starve to death in spite of any crash programs embarked on now.

Ehrlich 2019s prophecy, of course, proved wrong, for reasons that Bricker and
Ibbitson elegantly chart in Empty Planet. The green revolution, a series of
innovations in agriculture that began in the early twentieth century,
accelerated such that crop yields expanded to meet humankind 2019s needs.
Moreover, governments around the world managed to remediate the worst effects
of pollution and environmental degradation, at least in terms of daily living
standards in multiple megacities, such as Beijing, Cairo, Mexico City, and
New Delhi. These cities face acute challenges related to depleted water
tables and industrial pollution, but there has been no crisis akin to what
was anticipated.\u00a0\n\nYet visions of dystopic population bombs remain deeply entrenched, including
at the center of global population calculations: in the forecasts routinely
issued by the United Nations. Today, the UN predicts that global population
will reach nearly ten billion by 2050. Judging from the evidence presented in
Morland\u2019s and Bricker and Ibbitson\u2019s books, it seems likely that this
estimate is too high, perhaps substantially. It\u2019s not that anyone is
purposely inflating the numbers. Governmental and international statistical
agencies do not turn on a dime; they use formulas and assumptions that took
years to formalize and will take years to alter. Until very recently, the
population assumptions built into most models accurately reflected what was
happening. But the sudden ebb of both birthrates and absolute population
growth has happened too quickly for the models to adjust in real time. As
Bricker and Ibbitson explain, \u201cThe UN is employing a faulty model based on
assumptions that worked in the past but that may not apply in the future.\

Population expectations aren't merely of academic interest; they are a key
element in how most societies and analysts think about the future of war and
conflict. More acutely, they drive fears about climate change and
environmental stability\u2014especially as an emerging middle class numbering in
the billions demands electricity, food, and all the other accoutrements of
modern life and therefore produces more emissions and places greater strain
on farms with nutrient-depleted soil and evaporating aquifers. Combined with
warming-induced droughts, storms, and shifting weather patterns, these trends
would appear to line up for some truly bad times ahead.\n\nExcept, argue Bricker and Ibbitson, those numbers and all the doomsday \nscenarios associated with them are likely wrong. As they write,
We do not face the challenge of a population bomb but a population bust a relentless,
generation-after-generation culling of the human herd.\u201d Already, the signs
of the coming bust are clear, at least according to the data that Bricker and
Ibbitson marshal. Almost every country in Europe now has a fertility rate
below the 2.1 births per woman that is needed to maintain a static
population. The UN notes that in some European countries, the birthrate has
increased in the past decade. But that has merely pushed the overall European
birthrate up from 1.5 to 1.6, which means that the population of Europe will
still grow older in the coming decades and contract as new births fail to
compensate for deaths. That trend is well under way in Japan, whose
population has already crested, and in Russia, where the same trends, plus
high mortality rates for men, have led to a decline in the population.

What is striking is that the population bust is going global almost as
quickly as the population boom did in the twentieth century. Fertility rates
in China and India, which together account for nearly 40 percent of the
world\u2019s people, are now at or below replacement levels. So, too, are
fertility rates in other populous countries, such as Brazil, Malaysia,
Mexico, and Thailand. Sub-Saharan Africa remains an outlier in terms of
demographics, as do some countries in the Middle East and South Asia, such as
Pakistan, but in those places, as well, it is only a matter of time before
they catch up, given that more women are becoming educated, more children are
surviving their early years, and more people are moving to cities.

Morland, who, unlike Bricker and Ibbitson, is a demographer by training, is
skeptical that humanity is on the cusp of a tectonic reversal in population
trends. He agrees that the trends have changed, but he is less prone to the
blanket certainty of Bricker and Ibbitson. This is not because he uses
different data; he simply recognizes that population expectations have
frequently been confounded in the past and that certainty about future trends
is unreasonable. Morland rightly points out that even if fertility rates fall
dramatically in Africa, there will be decades left of today\u2019s youth bulge
there. Because he is more measured in his assessment of the ambiguities and
uncertainties in the data, Morland tends to be more circumspect in drawing
dramatic conclusions. He suggests, for instance, that China\u2019s population
will peak short of 1.5 billion in 2030 and then stagnate, with an aging
population and gradual absolute decline thereafter. Bricker and Ibbitson, on
the other hand, warn that China\u2019s fertility rate, already in free fall,
could actually get much worse based on the example of Japan, which would lead
China to shrink to less than 700 million people in the second half of the
century. Morland does agree with Bricker and Ibbitson on one important point:
when it comes to global population, the only paradigm that anyone has known
for two centuries is about to change.

GREAT EXPECTATIONS
The implications of the coming population bust occupy a large portion of
Bricker and Ibbitson\u2019s book, and they should occupy a much larger portion
of the collective debate about the future and how to prepare for it. The
underlying drivers of capitalism, the sense that resource competition and
scarcity determine the nature of international relations and domestic
tensions, and the fear that climate change and environmental degradation are
almost at a doomsday point\u2014all have been shaped by the persistently
ballooning population of the past two centuries. If the human population is
about to decline as quickly as it increased, then all those systems and
assumptions are in jeopardy.\n\nBoth books note that the demographic collapse could be a bright spot for
climate change. Given that carbon emissions are a direct result of more
people needing and demanding more stuff\u2014from food and water to cars and
entertainment\u2014then it would follow that fewer people would need and demand
less. What\u2019s more, larger proportions of the planet will be aging, and the
experiences of Japan and the United States are showing that people consume
less as they age. A smaller, older population spells some relief from the
immense environmental strain of so many people living on one finite globe.

That is the plus side of the demographic deflation. Whether the concomitant
greening of the world will happen quickly enough to offset the worst-case
climate scenarios is an open question\u2014although current trends suggest that
if humanity can get through the next 20 to 30 years without irreversibly
damaging the ecosystem, the second half of the twenty-first century might be
considerably brighter than most now assume. The downside is that a sudden
population contraction will place substantial strain on the global economic
system. Capitalism is, essentially, a system that maximizes more\u2014more
output, more goods, and more services. That makes sense, given that it
evolved coincidentally with a population surge. The success of capitalism in
providing more to more people is undeniable, as are its evident defects in
providing every individual with enough. If global population stops expanding
and then contracts, capitalism\u2014a system implicitly predicated on
ever-burgeoning numbers of people\u2014will likely not be able to thrive in its
current form. An aging population will consume more of certain goods, such as
health care, but on the whole aging and then decreasing populations will
consume less. So much of consumption occurs early in life, as people have
children and buy homes, cars, and white goods. That is true not just in the
more affluent parts of the world but also in any country that is seeing a
middle-class surge.

But what happens when these trends halt or reverse? Think about the future
cost of capital and assumptions of inflation. No capitalist economic system
operates on the presumption that there will be zero or negative growth. No
one deploys investment capital or loans expecting less tomorrow than today.
But in a world of graying and shrinking populations, that is the most likely
scenario, as Japan\u2019s aging, graying, and shrinking absolute population now
demonstrates. A world of zero to negative population growth is likely to be a
world of zero to negative economic growth, because fewer and older people
consume less. There is nothing inherently problematic about that, except for
the fact that it will completely upend existing financial and economic
systems. The future world may be one of enough food and abundant material
goods relative to the population; it may also be one in which capitalism at
best frays and at worst breaks down completely.

The global financial system is already exceedingly fragile, as evidenced by
the 2008 financial crisis. A world with negative economic growth, industrial
capacity in excess of what is needed, and trillions of dollars expecting
returns when none is forthcoming could spell a series of financial crises. It
could even spell the death of capitalism as we know it. As growth grinds to a
halt, people may well start demanding a new and different economic system.
Add in the effects of automation and artificial intelligence, which are
already making millions of jobs redundant, and the result is likely a future
in which capitalism is increasingly pass.

If population contraction were acknowledged as the most likely future, one
could imagine policies that might preserve and even invigorate the basic
contours of capitalism by setting much lower expectations of future returns
and focusing society on reducing costs (which technology is already doing)
rather than maximizing output. But those policies would likely be met in the
short term by furious opposition from business interests, policymakers, and
governments, all of whom would claim that such attitudes are defeatist and
could spell an end not just to growth but to prosperity and high standards of
living, too. In the absence of such policies, the danger of the coming shift
will be compounded by a complete failure to plan for it.

Different countries will reach the breaking point at different times. Right
now, the demographic deflation is happening in rich societies that are able
to bear the costs of slower or negative growth using the accumulated store of
wealth that has been built up over generations. Some societies, such as the
United States and Canada, are able to temporarily offset declining population
with immigration, although soon, there won't be enough immigrants left. As
for the billions of people in the developing world, the hope is that they
become rich before they become old. The alternative is not likely to be
pretty: without sufficient per capita affluence, it will be extremely
difficult for developing countries to support aging populations.

So the demographic future could end up being a glass half full, by
ameliorating the worst effects of climate change and resource depletion, or a
glass half empty, by ending capitalism as we know it. Either way, the
reversal of population trends is a paradigm shift of the first order and one
that is almost completely unrecognized. We are vaguely prepared for a world
of more people; we are utterly unprepared for a world of fewer. That is our
future, and we are heading there fast.