The Seven Demographic Trends That Will Determine Our Global Future

As the coronavirus pandemic continues to take its toll on the world’s population, two of the world’s most powerful countries, China and the United States, have released troubling new census data. Both countries, it seems, are facing national demographic declines that may soon threaten their economic prosperity—though the former will be much more affected than the latter. 

In April, the U.S. Census Bureau reported the slowest population growth—7.7 percent in a decade—since the 1930s. The nosedive was due to a combination of a declining birth rate, decreased immigration flows and significant mortality amid the COVID-19 pandemic. As a result, the U.S. population, which was 331 million in April 2020, grew by just 900,000 in 2019. 

Meanwhile, in China, the government announced in May that couples would henceforth be allowed to have a third child, amending the country’s infamous One-Child Policy for a second time. The impetus for this policy shift became clear weeks later, when Beijing published the results of its own 2020 Census. Though China’s population had grown by 11 million since 2010 to hit 1.41 billion, the data also revealed that the country’s birth rate is in free fall.  

These headlines are significant domestically in the U.S. and China, but they also allude to the fact that the first two decades of the 21st century were a turning point for the population of the world as a whole. Millions flocked to cities, global birth rates fell and each continent experienced its own demographic shifts. These dynamics, including the seven explored below, will have dramatic and large-scale impacts on the way we live in the decades to come.  

East Asia is falling over a cliff. In the 20th century, industrializing countries went through what’s known as a “demographic transition,” in which a decrease in mortality, brought on by improvements in economic prosperity and governance, was followed by a decrease in the number of births. East Asia is undergoing its own similar transition now, but at a much faster pace. Births in Japan and South Korea are at record lows, even as citizens of these countries have little appetite for policies that would encourage immigration. Researchers in both states have even launched studies to predict when their “last person” would die. Tohoku University’s 2012 investigation determined that the “last Japanese” would die in 3011—a few decades after the “last South Korean” in 2750, according to a 2014 study by the National Assembly Research Service. 

In China, falling birth rates have often been blamed on the One-Child Policy, instituted in 1979 by Chinese leader Deng Xiaoping. In fact, the Chinese predicament is not a result of Maoist ideology. The decline started in the late 1960s, and China has mostly been following the East Asian trend, albeit at a faster clip. 

By 2060, nearly one in five Chinese men over 70 years of age will lack descendants, leaving them dependent on the state for support.

China is doubly affected by a traditional “preference for males,” also found in other societies—notably in India and the Caucasus—that leads some parents to terminate pregnancies when the fetuses are known to be female, an unwanted result of the large-scale availability of ultrasound scanning. China’s recent census revealed that there are 35 million more men than women in the country—a gender ratio of roughly 1.1 male births per 1 female birth. At a local level, the disparity can increase, reaching 1.3 or 1.4. 

A skewed gender ratio has durable consequences, especially when the number of girls is further reduced by infanticides or deliberate neglect. Throughout history, it has often led to social instability and an increased criminality. The problem for Beijing is that lifting the single-child restriction in 2015 has not slowed the national population decline. The number of births has decreased for four consecutive years, collapsing to 12 million as of the 2020 census, with a fertility rate of just 1.3 children per women. China now risks being stuck in the “low-fertility trap,” from which it is difficult to escape. As a result, in less than two decades, 30 percent of its population will be over 60 years old. 

Because it is so rapid, China’s aging will undoubtedly have consequences on its economic performance, as well on its ability to sustain its elderly. Today, China’s retirees depend on family assistance for roughly half of their income, but the average Chinese household size now has fewer than three members for the first time in recorded history. By 2060, nearly one in five men over 70 years of age will lack descendants, leaving them dependent on the state for support. 

Europe is only growing through immigration. For 30 years, Eastern Europe has been suffering what can be called a “population triple whammy”: a decrease in births, an increase in deaths and an increase in emigration. Georgia, Latvia, Lithuania, and Bosnia and Herzegovina have lost more than 20 percent of their populations since 1990. This might explain the prevalent fears in these countries and in other parts of Europe that nationals are being “replaced” by immigrants and refugees. Russia is experiencing a similar trend, though it has been welcoming an increasing number of immigrants from Central Asia. 

Some on the Old Continent fear that the population growth in African countries could lead to a “scramble for Europe.” Indeed, a recent book with that title, authored by Duke University professor Stephen Smith, claimed that Africa will be to Europe what Mexico was to the United States until recently: a large source of labor immigration, both legal and illegal. 

But the direst projections made by Smith and others like him don’t hold up on close scrutiny. It is certainly true that as their countries develop, Africans will be increasingly able to afford a transcontinental journey. But for now these economies remain far below the level of wealth that would make that possible, and geographical constraints are more prohibitive between North African states and Southern Europe than on the American landmass. Whereas Smith claims that 150 million Africans will come to Europe between now and 2050, the EU’s own projections, based on more solid analysis, suggest that approximately 800,000 to 1 million would immigrate each year by midcentury.

On the other hand, some have argued that immigration from Africa could balance out demographic downticks in Europe and elsewhere. Not so fast. In 2019, there were 272 million migrants in the world. According to a 2000 study by the U.N. Population Division, aging countries in Europe would need 1.3 billion immigrants over a period of 50 years to maintain their current ratio of working age to non-working age populations. In South Korea, the number was 5.1 billion.

Nigeria, India and America are the future. Sub-Saharan Africa is the only region that has yet to experience its demographic transition. Niger actually holds the world record for fertility. In the region of Maradi, in the country’s south, each woman will on average have 8 children. In general, sub-Saharan Africa is expected to see significant growth in the coming decades: The U.N. estimates its population could increase from 1.3 billion to 4.2 billion by the end of the century. Others have made more conservative estimates, but all of the projections agree that Nigeria will be a demographic superpower by 2100—the third-most populous country in the world, with the second-largest working-age population, according to The Lancet. 

India, meanwhile, is undergoing its demographic transition, but because it is so large, the country will still contribute the most births—273 million—to the global population between 2020 and 2050. That same Lancet study found that India’s working-age population will surpass China’s in the mid-2020s and become the world’s largest by 2100. 

Nevertheless, the study predicted that the United States will remain an economic superpower, largely due to immigration flows, with the world’s fourth-largest working-age population and a GDP that could again exceed China’s by 2098. As China ages out, African countries and India will join the United States as leading world economies.

Aging countries in Europe would need 1.3 billion immigrants over a period of 50 years to maintain their current ratio of working age to non-working age populations.

We are now an urban species. At some point in the late 2000s—the exact timing is difficult to pinpoint—humanity became an urban species, with more than half of the world living in cities. According to a 2018 United Nations report, that share will grow to nearly 70 percent by 2050. There are already roughly 30 “megacities” with populations over 10 million, and that number is set to grow, especially in Asia. As a result, coastal hubs will host an increasing number of inhabitants. One could say that the large coastal city is the future of humankind—a model which of course raises sustainability questions in the event of a significant rise in sea levels.  

COVID-19 will only make a dent in the evolution of the world’s population. There is wide agreement that the official number of COVID-19 deaths, 4.3 million, is underestimated. According to a Washington State University study released in May, the real tally is double that, closer to 7 million; The Economist put it even higher, at 10 million. It is a devastating loss, but when compared to previous global pandemics, COVID-19 appears to have had much less impact on population. The total number of deaths worldwide in 2019 was 58 million, and the Earth’s population grows by around 80 million a year. In contrast, the 1918 flu pandemic, which killed about 50 million, reduced the world’s population by 1 to 5 percent. Centuries earlier, the Black Death may have killed half of the world’s population at the time.  

Still, COVID-19 is having an important impact on the population of certain countries. The most affected ones, in terms of deaths per million inhabitants, are almost all in Eastern Europe: Hungary, the Czech Republic, Bosnia and Herzegovina, Azerbaijan and Bulgaria. Here, the coronavirus pandemic will exacerbate the existing demographic crisis.

Older adults are now more numerous than infants. Despite these complex national trends and the concentrated areas of growth, the age structure of the world is changing. Due to advances in medicine that prolong life and a declining overall birth rate, adults over 65 years old now constitute 10 percent of the world’s population and will reach at least 15 percent of it by 2050. The global median age is now 31, compared to 22 in 1965. 

This aging of the world raises significant questions about health care and pensions. It is possible that the world will adjust to a longer working life, on the condition that those aged 60 in 2050 are as healthy as, say, those aged 50 in 2020. But humanity is so far aging faster than countries are making the needed reforms to address the problem. It’s therefore likely that the transition to an older society will be accompanied by serious social unrest in countries that do not have generous pensions systems already in place.  

The good news is that, all other things being equal, an older world could very well be a more peaceful one. One of the most politically useful findings of population studies in recent decades has been that there is a tight correlation between a society’s age structure—or, more precisely, the relative shares of young and older populations—and its propensity to violence. This trend has been used to explain, for example, why African countries, which all have a median age of 33 years old or lower, witness so much internal strife and civil conflict. Thus, in a few decades, after the demographic transition is complete at the global level, the world should be a better place.   

We may be heading for a “big crunch.” In 2019, the United Nations’ Department of Social and Economic Affairs predicted, as its baseline scenario, that the world’s population will hit 10.8 billion by 2100, and that fertility will hover around the 2.1 replacement rate. This looks almost too good to be true. In fact, other institutions envision that the Earth’s population will sharply decrease by the end of the century. 

The Vienna-based International Institute for Applied Systems Analysis believes that this reduction will happen as early as 2070 and that the global population will have dropped from a high of 9.5 billion down to 9 billion by 2100. A more recent study in The Lancet claims that fertility is likely to decline faster than the U.N.’s projection, particularly in Africa, and that humans will number only 8.8 billion by 2100. No less than 23 countries across Asia and Europe are predicted to lose more than half of their populations by that time. 

The good news is that, all other things being equal, an older world could very well be a more peaceful one.

It is overwhelmingly difficult for countries to recover when their fertility rates fall too far below the level of replacement—generally speaking, below 2.1 children born per woman. The Lancet forecasts an average fertility rate of 1.7 at the global level by the end of the century. Humankind has no experience with sustaining such low fertility almost everywhere in the world. This would truly be unchartered territory. 

In the world of cosmology, a once-popular theory posited that the universe would expand and expand until gravitational forces eventually reversed the trend, causing it to contract and collapse. Is global population similarly doomed in the long run, headed for its own “big crunch”?

It’s hard to say, because the world’s population cannot be projected beyond 2100 in a useful way. In 2005, the U.N. devised heuristic tools to project the human population at 2300 and demonstrated that fertility was the key variable in determining the very long-term future of the planet: Adding or subtracting a few decimal points to the 2.1 replacement rate could lead to an Earth inhabited by 36 billion people three centuries from now—or by just 2 billion. In other words, the difference between a “Nigerian” future and a “Japanese” one.

Still, what we do know about this century is illuminating. Paul Morland, a leading scholar of demography at University College, has said that in the 21st century, the world’s colors will show “less white, more grey, and more green.” Less white, because African populations will grow more rapidly than Western ones; more gray, because aging will affect almost all countries; and more green, because a richer and stabilized world population is, by and large, good news for the environment. It may also be, for the reasons stated above, a more peaceful one.

Bruno Tertrais is the deputy director of the Paris-based Fondation pour la Recherche Strategique (Foundation for Strategic Research). He was a member of the 2007 and 2012 presidential commissions on the White Paper on Defense and National Security.