The future of world population and the shifts ahead
The end of this century is expected to bring notable changes in how people are spread around the world. Initially, India is projected to overtake China as the most populous nation, while several African countries, including the Congo region, are set to grow rapidly. Meanwhile, Spain could lose about half of its current inhabitants, shrinking from around 46 million to roughly 23 million. These patterns have appeared in multiple longitudinal studies that apply the same criteria: after a period of growth, humanity is likely to enter a gradual decline for several decades.
From an environmental standpoint, the overall drop in population would likely reduce planetary pressures, yet new challenges would emerge. Governments would need to sustain and support an aging population with a shrinking workforce, all while maintaining economic stability and social services.
Overall, the world population is projected to peak near 9.7 billion around 2064 and then fall to about 8.8 billion by century’s end. This trend aligns with findings that emphasize broader access to education and contraception, which help explain the slowdown in birth rates. The Lancet reports and corroborating work from researchers in 2020 and after support these conclusions.
The planet may undergo major demographic changes, which are summarized in global population projections and corresponding charts that illustrate country-by-country variations.
Across many countries, fertility rates are not expected to stay at current levels by 2100. In a survey of 195 countries, researchers from a leading health metrics institute estimate that most will not maintain present population sizes without continued changes in birth rates. In particular, a group of nations including Japan, Thailand, Italy and Spain could see declines exceeding 50 percent. Such findings were reported by a Lancet-backed analysis and reviewed by other scholars in later years.
Projected shifts among major populations
In contrast to a slowing or shrinking older populations in some parts of the world, Sub-Saharan Africa could see its numbers triple in the same period. This would create a striking dynamic where nearly half of humanity could reside in Africa by century’s end, according to Lancet-supported projections. A notable consequence is the anticipated decline in the working-age population in large economies like China, which could face slower growth and new welfare challenges as it transitions away from being the most populous nation.
Warnings from the study emphasize that a shrinking labor force will influence economic momentum and public programs such as health care and pensions. The projection for China is a population near 732 million at the end of the century, compared with today’s about 1.4 billion.
Nevertheless, migration can mitigate these declines. Countries with open immigration policies may offset lower birth rates and preserve population size, supporting economic vitality in places with aging societies like the United States, Canada, and Australia.
As one researcher explained to major news outlets, the world has moved from concerns about too many people to the possibility of too few. The tipping point is real, and it will push governments to adapt quickly to a changing age structure.
Europe and Asia face pronounced decline
By around 2100, Asia and Central and Eastern Europe are expected to see the fastest population decreases. Estimates suggest Japan could drop from about 128 million in 2017 to around 60 million in 2100, while Thailand might fall from 71 million to about 35 million. Countries like Spain, Italy, Portugal, and South Korea could all lose significant shares of their populations. In addition, roughly one-third of other nations could experience declines of up to half their populations.
Beyond shifts in total numbers, the aging of societies will shape economies and public life. There will be more people in need of government support and fewer people contributing taxes, a dynamic that could transform how social programs are funded and organized.
Migration as a key factor
Migration is seen as a potential counterbalance to fertility declines. Countries that welcome immigrants may maintain population levels and support growth even as birth rates fall. As one researcher noted, when births fall short of deaths, immigration becomes essential to keep the population stable.
While the overall environmental impact of a smaller population could be mixed, the aging population brings its own set of challenges. The inverted age structure poses questions about how societies are organized, how economies function, and how taxes are collected and allocated.
Note: The material above reflects findings from major demographic studies and reports. The Lancet is a primary source for some of these projections, and additional peer-reviewed analyses have supported these conclusions over time.
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