The global population is projected to peak around 2084 at just under 10.3 billion people, then begin a sustained decline. That’s according to the United Nations’ most recent projections, published in 2024. But not all forecasters agree on the timing, and the answer depends heavily on what happens with birth rates in a handful of key regions over the coming decades.
What the Major Forecasts Say
The UN’s 2024 revision of its World Population Prospects puts the global peak at 2084, with about 10.3 billion people. That’s slightly earlier than its previous estimate from 2022, which placed the peak in 2086 at around 10.4 billion. The shift reflects faster-than-expected fertility declines in several countries.
A separate forecast published in The Lancet by researchers at the Institute for Health Metrics and Evaluation paints a more dramatic picture. That model projects the population could peak much sooner, just after mid-century, at roughly 9.7 billion in 2064, then fall to about 8.8 billion by 2100. The difference comes down to assumptions about how quickly women in lower-income countries gain access to education and contraception. More optimistic assumptions on those fronts mean faster fertility drops and an earlier peak.
So depending on which model you trust, the global population could begin shrinking anywhere from the 2060s to the mid-2080s.
Why Growth Continues Even as Birth Rates Fall
The global fertility rate in 2024 was 2.2 births per woman, barely above the 2.1 “replacement level” needed for a population to sustain itself without immigration. That’s a steep drop from around 5 births per woman in the 1960s and 3.3 as recently as 1990. Over half of all countries (55 percent), representing more than two-thirds of the global population, already have fertility rates below replacement.
If most of the world is already below replacement, why is the population still growing? The answer is demographic momentum. When a country has spent decades with high birth rates, it ends up with a large share of young people. Even after families shrink to two children or fewer, all those young people are still entering their childbearing years. The population keeps expanding for decades simply because so many people are of reproductive age. It’s like a freight train that takes a long time to stop after the brakes are applied.
Countries Already in Decline
Population decline isn’t a future event everywhere. Several countries are already shrinking. China recorded its first annual population drop in 2022 after six consecutive years of falling birth rates. UN projections show China’s population falling from 1.43 billion in 2022 to 1.31 billion by 2050, then dropping below 800 million by 2100. That’s a loss of more than 600 million people in less than 80 years.
Japan, South Korea, Italy, and much of Eastern Europe have been on similar trajectories for years. South Korea’s fertility rate has fallen below 1.0 births per woman, less than half of replacement level. These countries offer a preview of what population decline looks like in practice: school closures, labor shortages, rising pressure on pension systems, and towns that slowly empty out.
Sub-Saharan Africa Is the Counterweight
The main reason the global population keeps growing despite all these declines is sub-Saharan Africa. The region’s population is forecast to triple between 2017 and 2100, reaching roughly 3 billion people. Countries like Nigeria, Chad, Mali, Niger, and South Sudan are not expected to see their populations peak before 2100 at all. North Africa and the Middle East are also projected to grow by about 63 percent over the same period.
The pace of fertility decline in sub-Saharan Africa is the single biggest variable in global population projections. If education and contraceptive access expand quickly, the global peak could arrive decades earlier. If progress stalls, the world could remain near its peak population well into the 2100s. Some researchers have argued that sub-Saharan Africa could actually exceed current projections if development doesn’t accelerate as expected.
What Drives Fertility Down
The pattern is remarkably consistent across countries and cultures. Two factors matter most: women’s education and access to contraception. Women who complete secondary school and attend college delay childbearing and have fewer children overall. Urbanization reinforces this, as the economic calculus of raising children shifts dramatically when families move from farms to cities. Children go from being extra hands in the field to an expensive, decades-long investment.
These forces have proven powerful enough to override government efforts to boost birth rates. Countries like Japan, South Korea, and Singapore have spent billions on pro-natalist policies, offering cash bonuses, subsidized childcare, and parental leave. None have managed to reverse their fertility declines in any meaningful way. Once birth rates fall, they tend to stay low.
What a Declining Population Means
The economic consequences are already visible in countries at the leading edge of this shift. The core challenge is the ratio of retirees to working-age adults. In parts of Europe, projections suggest that older individuals will account for nearly a third of the population by 2050, with fewer than two working-age people supporting every retiree. That math strains healthcare systems, pensions, and tax bases simultaneously.
Labor shortages are the most immediate pressure point. Sectors like elder care, construction, and agriculture struggle to fill positions when the working-age population contracts. Immigration can partially offset this, but it creates political friction and doesn’t fully solve the dependency ratio problem if immigrants also age in place. Automation is the other commonly cited solution, though its ability to replace human labor in care work and other hands-on fields remains limited.
There are potential upsides. A smaller population means less pressure on housing, natural resources, and ecosystems. Carbon emissions could fall. Competition for land and water may ease. Whether those benefits materialize depends on whether the economic disruptions of the transition are managed well enough to avoid prolonged stagnation in the countries that shrink first.