On November 15, 2022, humanity reached a staggering 8 billion people living on Earth. Yet although global population growth has been a constant throughout most of human history – accelerating to previously unseen levels during the last century – it will soon run out of steam. The next 50-60 years are predicted to be characterised by high rates of growth, but projections show that the pace of growth is slowing down, suggesting that the population curve of humanity will flatten out, and eventually bend towards decline.

In some countries, this shift has already occurred. With recent news of China entering a state of negative population growth ten years earlier than expected, there is much uncertainty and concern surrounding the impact of the ongoing demographic shifts on the political stability in the region, as well as on the global economy.

Similarly, the Japanese Prime Minister Fumio Kishida recently went public expressing worries over Japan’s falling birth rates, warning that the country is on the brink of being unable to maintain social functions. Japan’s population currently numbers approximately 125 million. If birth rates, life expectancy, and net migration remains stable, the population will fall to 50 million by 2100, 10 million by 2200, and no more than 62 people by the year 3000, according to the Japanese Department for Population and Social Security Research.

Although Japan’s situation may be dire, the switch from growth to decline on a global level is not due until later this century. Despite this, population shrinkage has already become a hotly debated issue. Among those who have expressed concern over dwindling populations are Darrell Bricker and John Ibbitson, authors of An Empty Planet: The Shock of Population Decline. They argue that most publicly recognised population projections are too optimistic in their expectations of continued growth, and that the disruptive social and economic effects of declining birth rates will therefore start setting in much sooner than expected. When facing population collapse, the authors believe, it will be the countries embracing immigration with attractive living conditions that fare best, while those clawing to political isolationism and protectionism will fall victim to their own short-termism.

Of course, Bricker and Ibbitson are not the first to issue a warning. Nor are they the first to point out the considerable uncertainty surrounding the most cited population projections, which often reach almost a century into the future. A glance at some of these projections will reveal major disagreements over when the size of the global population will reach its apex, as well as when growth will turn into decline. The United Nations’ Population Division, for example, estimates that we will peak around 2080 at 10.8 billion and eventually flatten out towards 2100. The International Institute for Applied Systems Analysis, on the other hand, projects that we will reach 9.4 billion in 2070 before steadily falling to 9 billion at the end of the century. One of the most radical projections, authored by the Institute for Health Metrics and Evaluation (IHME) at the University of Washington, suggests that we will reach 9.7 billion already in 2064 before falling to 8.8 billion in 2100. The IHME estimates that the global fertility rate could decline to 1.66 children per woman by 2100 – in comparison to the 2.3 per woman today – which means the global population would drop as low as 2.3 billion by the year 2300.

Despite their differences, what most projections have in common is the assumption that the global population will, at some point, reach its peak, after which it will start dropping. Many of the reasons for this projection are identical to why the growth rate has been falling since the 1950s. One major factor is increasing reproductive freedom. As women, particularly in the Global South, become better equipped to control the timing and number of pregnancies they want to have, the allure of greater affluence and autonomy will accelerate the trend of falling fertility rates. General improvements in the socioeconomic conditions of developing countries will increase the number of women in education and employment, with many more choosing to prioritise career and leisure over the time-consuming and expensive brunt of procreation. Although projections cannot factor in upsets that might significantly change the outlook – pandemics, wars, pronatalist policy reforms, new social norms, and changing family preferences – the overall trend towards fewer births and, eventually, negative growth looks relatively certain.

South Korea provides an example of what might eventually be in store for much of the world as the trend of falling fertility rates continues. Here, the fertility rate has been well below the replacement level of 2.1 births per woman since 1983. In 2018, the country became the first in the world to see a fertility rate below 1, a record which was once again broken in 2022, when the average number of children born to each woman sunk to a new low of 0.81. To slow the rapid decline, the South Korean government has enacted financial incentives for expecting couples to alleviate the high cost of raising children in the country. They have also enacted subsidies for child- and eldercare benefits, as well as having created new foreign guest worker programmes in order to turn the trend.

It should be noted that South Korea’s low fertility rate is an exceptional case which is a result of the country’s unique circumstances, not least the high cost of housing, education, and general economic anxiety among the country’s younger population. Accordingly, expectations that the entire world will soon follow suit should be taken with a grain of salt. Although Elon Musk recently drew headlines and sparked worry with his warnings of a global population collapse beginning as early as 2040, few demographers put any stock in such a notion. Indeed, one UN demographer commented in response to Musk’s recent attention-grabbing proclamation that “he’s better off making cars than at predicting the trajectory of the population.” With that said, few see population decline as having a positive impact on society due to the serious social and economic pressure it can cause. What’s in store for us in a future where population growth, a stable trend through most of human history, reverses its course?

Even before reaching a state of decline, the consequences of the demographic changes will be felt. Aging populations and worker shortages could cause serious societal disruptions, including in the form of a growing pressure on healthcare and other social security services. With the total amount of retirement incomes rising every year, public pension plans are also at risk in the countries where such schemes exist. As populations age and eventually shrink, less consumption of goods and services will almost certainly cause a slowdown in economic activity – although there may be other benefits, including environmental ones. A smaller tax base would also bring with it its own set of challenges in the form of lower budgets for public expenditure. Although one could conceive of benefits as well – fewer workers would command higher wages and fewer property buyers could lead to more affordable housing – overall, the economic challenges are likely to be considerable.

Naturally, the size and scope of these challenges will vary greatly between countries and regions. Nations with low fertility combined with net zero or negative migration – much of Eastern Europe is included in this cohort – may face labour shortage issues sooner than countries with fertility rates below the replacement threshold but where net positive migration makes up for the loss to some degree. Spain, France, Great Britain, and Germany fall under this category. Over the course of the next century, however, current levels of migration will not be enough to prevent population decline in these countries either. Major countries that are expected to see population growth toward 2100 – this group includes the United States, India, and Nigeria – may see benefits from a larger workforce and potential consumer base if they can provide adequate education, employment opportunities, and infrastructure to support that population.

Japan may offer some clues for what’s to come in countries with faltering fertility rates and low rates of migration. With 28.7% of the population now aged 65 and older, the country has the highest share of elderly citizens in the world. On top of this, Japan’s high life expectancy has meant that 80,000 Japanese citizens are now centenarians – another world record.

Among the challenges facing Japan, some of which will soon become familiar in many other parts of the world as well, are increased economic and budgetary constraints, a growing pressure on job markets, and rural depopulation. Partly through necessity, the country has positioned itself at the forefront of the development of robotics and other technologies aimed at alleviating the challenges of a shrinking workforce and a growing share of elderly citizens.

As fertility rates continue to decline, we will also likely see increased efforts at developing methods to bypass the limitations of human biology. This will almost certainly include increased funding for fertility research and treatment practices aimed at increasing the timespan in which women are able to carry on a pregnancy. Artificial wombs could also potentially help infertile couples conceive a child while completely removing the child-per-woman variable from the population equation. It is uncertain, however, if such developments will do much to impact the overall trend toward decline.

Some effects of a shrinking and aging population may be hard to quantify, but nonetheless important. There may, for instance, be social and cultural impacts related to community vitality and the loss of innovative ‘spirit’ (something which is commonly associated with youth). Additionally, as population decline accelerates, so might the loss of cultural traditions and heritage.

Finally, it is not unthinkable that the population shifts over the course of the 21st century will have profound impacts on a geopolitical level as well. Bricker and Ibbitson, the aforementioned authors of An Empty Planet, have speculated that we might see (or at least could hope to see) a ‘geriatric peace’ forming in a world where declining and aging populations means that the youth become a more precious resource not to be squandered on war; the few young will simply be needed elsewhere. Indeed, one of the consequences of Russia’s invasion of Ukraine, which has led to high casualties on both sides as well as the migration of young men in the fighting age, is a deepening of the demographic crisis facing the two nations. Ukraine is especially affected, as its fertility rate sits at a low 1.22 births per woman (with Russia’s sitting at 1.50).

Regardless of the exact trajectory of growth and decline, the era we are entering is unprecedented in human history. The potential consequences are wide-ranging, the full scope of change is impossible to grasp, and there are presently more questions than answers. Yet although the overall demographic trends may be largely irreversible, how we prepare and react to them is not set in stone. Will we be able to adapt to this new reality, or will we face widespread social and economic upheaval?

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