Weird Scenes from a Shrinking Planet (Part 1)

Image by Midjourney.

In my last essay I returned to the subject of the global fertility collapse, the unexpected and underappreciated trend that in my view confronts us with the permanent problem at its most devilish. What do I mean by that? Capitalism, by raising us into broad-based material prosperity, has provided us with sufficient resources and powers to allow the widespread development, exercise, and enjoyment of inborn capacities that would constitute mass human flourishing. We are thus confronted with what John Maynard Keynes referred to as mankind’s “permanent problem.” Alas, even as it brings the problem within our view, capitalist mass affluence creates conditions that make the continued ascent toward mass flourishing more difficult — see, for example, here, here, here, and here.

By inducing an ongoing drop in fertility that has spread around the world, capitalist mass affluence now threatens to short-circuit social progress altogether. More than half of humanity already lives in countries with sub-replacement fertility: the world as a whole will slip below that critical fertility threshold before too many more years go by. At that point, we will no longer be on the path to mass flourishing; on the contrary, we’ll be on the path to extinction. And while I don’t think it will come to that, we are nonetheless facing a dismal and dispiriting reversal in humanity’s trajectory: within sight of a future that can transform our highest ideals into a living reality for all, we have come to the collective decision that the future isn’t worth bothering about. We consequently face a future with a slackened tempo of innovation and dynamism — and steadily mounting pressures toward social disintegration and disorder. 

In this essay and the one that follows, I’d like to think through some of the implications of the great demographic reversal. All the usual caveats about predicting the future apply, and then some: with such a sharp break from the uninterrupted trend of centuries, and indeed from the larger trajectory of millennia, the path ahead is opaque indeed. What follows are some assorted musings on a future that could very well spin off in some deeply weird directions.

A challenge to our imaginations

As I’ve been trying to picture a world in the middle of a sustained, sharp drop in population — think of global fertility at current Chinese or South Korean levels and sustained for a normal human lifespan — I’m struck by how little that prospect has captured the public imagination. Low birth rates, at least in rich countries, have been with us for decades now: the first time I recall anyone noting the trend as a cause for concern was Ben Wattenberg’s 1987 book The Birth Dearth. Since then, there’s been a steady trickle of analyses and occasional soundings of the alarm as sub-replacement fertility has become a global phenomenon. But nothing has really caught on and made a big impression in a way that could even remotely rival the success of Paul Ehrlich’s The Population Bomb. Sci-fi treatments of overpopulation were ubiquitous during my boyhood, but other than the 2006 movie Children of Men — which dealt, not with depopulation due to low fertility, but imminent extinction because of a total cessation in new births — I can’t think of any portrayals in popular culture of a low-fertility, depopulated world. Zombie movies give us glimpses of an emptied-out world, but that’s about as close it gets.

I think this absence of attention is interesting. Perhaps our cultural response time has been slowed by the still-relatively-recent panic about overpopulation. Even today, worries about too many people and not enough space seem far more prevalent than the opposite — just check out the opposition at a zoning hearing to any new development, or the ongoing freakout over immigration. Maybe, though, the asymmetry in our attitudes about population goes far deeper than the scare stories of a half-century ago; maybe the roots extend back millennia. As my Niskanen colleague Matt Yglesias noted in a recent “Slow Boring” essay on the distortive effect of our “Malthusian intuitions,” the positive-sum world of modern economic growth has existed for a relative blink of the eye; for the vast bulk of the human experience, resources were basically fixed — such that adding more people meant less for everybody. Humanity has gone through this grim cycle countless times: a favorable shift in the climate or a new invention boosts crop yields, and for a while all are better off; over time, though, better times lead to more children surviving to adulthood and more mouths to feed, and living standards retreat back toward subsistence; eventually a plague or a stretch of bad weather shows up and there is a die-off, after which the survivors experience another upswing in prosperity. The lesson has been drummed into us with brutal repetitiveness: an influx of new people is a threat to wellbeing. It’s not that surprising, then, that we have difficulty unlearning it.

In any event, however deep the causes lie, the curious lack of public attention to this immensely fateful trend should raise our confidence in the resilience of the declining fertility trend. You’re not likely to see the enemy coming if you’re resolutely staring in the wrong direction.

Can’t stop it, but it will stop eventually

Population dynamics are all about stocks and flows: the flow of new births every year adds to the stock of population, the flow of deaths subtracts, and the difference equals the growth in population for the year (assuming births outnumber deaths). Because the size of the stock dwarfs that of the annual flows, even dramatic changes in the flow rate have a way of sneaking up on you. Let’s say the total fertility rate is cut in half in a single year — from 2.2 to 1.1 — and then persists indefinitely at that reduced rate. Let’s further assume, for simplicity’s sake, that the death rate stays constant. In the first year, the population continues to climb, albeit at something less than half the rate it did previously: the flow of new births has been halved, but the constant death rate applies to the large stock of population from high birth-rate cohorts. Every year, for many years, population continues to climb at an ever-diminishing rate. After 20 years or so, people from low-birth-rate cohorts begin entering the workforce and replacing retirees from high-birth-rate cohorts — and now you see the working-age population start to contract. As the first members of the low-birth-rate cohort reach reproductive age, birth rates plunge again. At some point after that, decades after the initial fall in fertility, the total population will start to fall.

Population decline from sub-replacement fertility is thus something like a tsunami: there is a considerable lag between what caused it and its eventual impact, but once it hits it’s driven by powerful momentum. Here in America the seas still appear calm and people are playing on the beach, but the waves are already ashore in some parts of the world and sweeping through the countryside.

Our actual situation differs in important respects from the hypothetical example above. For one thing, actual fertility rates are declining gradually rather than experiencing a sudden 50 percent drop in a single year; this stretches out the time scale over which population shifts occur. On the other hand, we are in the midst of sixty years of uninterrupted decline in total fertility worldwide and still there is no end in sight. Korea has already dropped well below the 1.1 figure in the hypothetical; China has reached it and still dropping. Meanwhile, the world death rate is projected to gradually increase due to the aging of the population; this accelerates the date when annual births slip below annual deaths.

Right now the global total fertility rate is 2.3. And the rate of decline has been accelerating recently: the rate in 2023 is down nearly 13 percent from 20 years ago, and nearly 10 percent from 10 years ago. The point is worth repeating: the global fertility decline isn’t leveling off, it isn’t approaching some steady-state; on the contrary, it’s speeding up. If the rate of decline over the past decade is maintained, the world will be below replacement fertility a decade from now. At this point, only a robust global baby boom that comes out of nowhere can prevent a period of depopulation.

Simple extrapolation tells us that any fertility rate below 2.1 is a path toward human extinction. Each generation will have fewer members than the one before, until eventually the number of people dwindles to zero. Simple extrapolation, however, is a notoriously unreliable guide to what the future will bring. In the present case, it’s crucially important that there is wide variation in fertility: the worldwide average may be 2.3 now, but individual female fertility is scattered over a considerable range. Indeed, a crucial factor dragging fertility downward is the rising number of women who go childless altogether: it’s estimated that over 40 percent of Japanese women born in 2005 will never have children, up from 27 percent for those born in 1970.

Meanwhile, there remain pockets of high-fertility subpopulations even in low-birth-rate countries — especially among traditional religious groups that set themselves apart from the larger society. Thus, in the United States, the overall average fertility rate is currently just under 1.8 — but the Amish and Ultra-Orthodox Jews both boast fertility rates of 6 and above.

The persistence of high-fertility subpopulations means that there will be no zeroing out of the human population. Over time, the high-fertility groups account for a rising percentage of the total population even as low-fertility groups in society gradually dwindle. At some point, the high-fertility groups will bulk large enough in the overall population to lift average fertility above replacement, and human numbers will start to edge upward again. From how low a base, though? How far will population have to fall before the rebound begins? Nobody knows.

Depopulation will be lumpy

According to a recent study in The Lancet, the total world population will peak in the 2060s at 9.7 billion and fall to 8.8 billion by 2100. That’s a roughly 10 percent decline by that point. But it’s important to recognize that 10 percent is just the global average: what happens in your locality could be very different. Amid all the uncertainties surrounding the future of population movements, one thing is clear enough: depopulation is going to hit different geographic areas very differently. As people thin out, they’ll also be on the move; as a result, some places will retain population or even grow while vast stretches empty out almost completely.

In addition to the master trend concerning human numbers — namely, fertility falling with rising wealth – there are two master trends concerning human movement across the planet. The first is urbanization; the second is international economic migration. These trends are really two sides of the same coin, which is that people move in the direction of economic opportunity. Domestically that means moving from the countryside to the city; globally that means moving from poor countries to rich countries.

During the long agrarian age, less than 5 percent of the world’s population lived in cities while almost everyone else was engaged in subsistence farming. By 1900, the urbanized share of global population had risen to 16 percent; it crossed the 50 percent threshold in the first decade of this century, and will approach 70 percent by 2050. Meanwhile, the world today is characterized by extreme economic inequality, as capitalist wealth creation has lifted many countries to affluence while barely making a dent in the least developed parts of the world: income in the richest countries is roughly 100 times that in the poorest countries. The huge variation in economic wellbeing and opportunity creates powerful incentives for people to relocate — provided, of course, that they are allowed in. Although immigration policies in the rich countries remain highly restrictive relative to the huge flows of people that might be unleashed by laissez faire, those policies have opened considerably in recent decades — and the result has been mass migration from the Global South into western Europe and North America.

As domestic and international population movements interact with global population decline, the upshot will be that big global cities continue to hold their own or even grow, as will those rich countries that maintain a relatively open door for migrants. For example, Japan’s population peaked around 2010, and since has fallen about 5 percent. Tokyo’s population, on the other hand, is higher than it was in 2010 (although it’s started to fall a bit in recent years) –the largest metropolitan area in the world, it now hosts 30 percent of the country’s population. Meanwhile, Japan now has some 8.5 million akiya, or abandoned houses, mostly in rural areas — roughly one in seven homes in the country are now unoccupied. Municipalities have set up akiya banks to list the homes and try to market them to foreigners fleeing the sky-high house prices of their NIMBY-fied homelands. Many of these houses are being sold for a pittance or even given away for free.

A shrinking planet will exaggerate current trends, but with ever-fewer cities growing or stable and ever-more extensive stretches of territory abandoned. National metropolises and regional economic centers will act as magnets attracting refugees from decline elsewhere in the country; the richest, most immigrant-friendly countries will do likewise on a global scale. Most second- and third-tier cities along with the countryside, and many countries as well, will see their emptying out accelerated as a result.

The geopolitics of depopulation

The variation in how depopulation hits will have major geopolitical ramifications. We have seen this happen before — with France, the original baby-bust country. France was the superpower of early modern Europe, and its strength rested on its large peasant population. In 1700, in the latter years of Louis XIV’s reign, France’s population of 20 million amounted to 20 percent of Europe’s total; France accounted for nearly 4 percent of the world’s population. Yet starting in the middle of the 18th century, triggered apparently by declining religiosity, France’s total fertility rate fell from 4.5 to 3.5 over the course of four decades. By the time of the revolutionary and Napoleonic wars, the effects had not yet registered: France could put over a million men in arms, and it took a succession of multi-country coalitions to finally bring her to heel.

But over the course of the 19th century, France’s slow demographic leak slowly but surely sapped its power. Here the great historian A. J. P. Taylor tells the tale:

The most startling change was in the position of France. For centuries she had been the most populous country in Europe. In 1850 she still outstripped every Great Power except Russia; she would have almost done so, even if Germany had been unified. By 1910 she was the least populous Power except Italy; and Italy was fast catching up. She had 14 per cent. of Europe’s population in 1850, less than 10 per cent. 50 years later. Against this, Prussia was only 5 per cent. of Europe in 1850; united Germany 15 per cent. in 1910. These figures counted psychologically. Men began to think statistically in the later nineteenth century; and France’s dwindling manpower helped to increase the loss of confidence, which had perhaps caused it.

France’s rapid, shocking defeat by a single country in the Franco-Prussian War of 1870 was the lightning bolt that revealed that the once mighty oak had been hollowed out. World War I represented the country’s last gasp as a great power; after being bled dry in that conflict, it was notoriously incapable of mounting resistance to the Nazi blitzkrieg two decades later.

We now face the prospect of another major scrambling of national power rankings — with potentially fateful implications. We have been waiting anxiously for the impoverished hellhole of North Korea to collapse, and perhaps it soon will. South Korea, meanwhile, which was even poorer than the North at the end of their inconclusive war, skyrocketed to European standards of living in the fastest dash from poverty to mass affluence ever recorded. In addition to its vastly greater economic output, South Korea also boasts twice the North’s population — 52 million versus 26 million. That population ratio, which has been fairly stable since the war, will not remain so, however: North Korea’s total fertility rate is a fairly respectable 1.8, while South Korea’s is in freefall at 0.7. As those trends play out, the longer-term future of the Korean peninsula may end up very different from the one we’ve all expected.

As to the biggest fault line in contemporary geopolitics, the one that has recently opened up between the United States and China, depopulation appears to have a silver lining. China’s spectacular economic rise has vaulted it to major power status, but what economic growth has given with one hand it is now taking with the other: China’s birth rate has collapsed, and so the foundations of its economic and political might are crumbling. According to the projections in The Lancet, China is on course to lose nearly half its population by the end of this century; the United States, by contrast, will stay basically flat.

But if population decline offers this reassurance over the longer term, for that very same reason short-term risks are elevated. You have to make hay while the sun shines, but the sun is sinking fast: accordingly, regarding China’s ambitions in Taiwan and elsewhere, there is pressure to act before conditions grow increasingly unfavorable.

More broadly, the global implications of population decline on peace and security look to be a mixed bag. On the one hand, global depopulation will badly hamper economic growth in many places, and it will put stress on institutional structures everywhere. More failed states are likely to sink into chaos; large migration flows as dwindling humanity reduces its geographic footprint could spark nasty conflicts and roil the politics of destination countries. On the other hand, when conflicts flare up, countries simply won’t have the young male bodies to pursue their interests effectively through violence. My best guess: the occasional bang against the backdrop of a long, echoing whimper.

OK, I’ll stop here for now so as not to overtax your patience. I’ll be back next week to conclude these musings.