The next century is expected to bring dramatic shifts in how the global population is distributed. At the outset, China is projected to lose its status as the most populous nation, with India taking that position. Population growth is anticipated across several regions, while countries like Spain may see substantial declines, potentially halving from about 46 million today to roughly 23 million. Researchers across multiple studies using consistent criteria forecast a period of rising numbers for several decades, followed by a gradual downturn in humanity’s total population.
From an environmental lens, this overall decline could lessen total planetary impacts, yet it will introduce new challenges. An aging population and a notable drop in labor participation are among the anticipated consequences, according to experts who study population trends.
Overall, global population is expected to peak near 9.7 billion around 2064 and decline to about 8.8 billion by century’s end, a pattern linked to rising female education levels and broader access to reproductive health services, as reported in a Lancet study and corroborated by subsequent work through 2020 and beyond.
By 2100, researchers from the Institute for Health Metrics and Evaluation at Washington University School of Medicine project that 183 of 195 countries will lack fertility rates sufficient to sustain their current populations. The accompanying chart illustrates country-based projections of population change.
Some 23 nations, including Japan, Thailand, Italy, and Spain, are expected to experience declines exceeding 50 percent, according to these researchers.
Population may fall to half in China
Sub-Saharan Africa could see its population triple within this century, creating a scenario in which almost half of the world’s population could reside in Africa by century’s end. This projection aligns with Lancet’s findings and highlights a projected sharp drop in the working-age population in countries such as China, potentially affecting growth, workforce dynamics, and welfare systems. In this scenario, China could stop being the most populous country, with a population around 732 million compared with today’s roughly 1.4 billion.
Immigration might offset declining fertility in some economies, offering relief for nations with low birth rates such as the United States, Canada and Australia. Researchers note the potential of migration to stabilize population trajectories and support economic vitality as fertility declines accumulate.
“Since the 1960s, the world has focused on the baby boom,” explained Christopher Murray, who led the research, in a media interview. “We are now at a tipping point, moving from too many people to too few.”
Population decline in Europe and Asia
Around 2100, the most rapid declines are anticipated in Asia and in Eastern and Central Europe. The projection suggests Japan could shrink from about 128 million in 2017 to around 60 million by 2100, while Thailand could drop from 71 to 35 million. Spain may fall from 46 million to about 23 million, Italy from 61 to 31 million, Portugal from 11 to 5 million, and South Korea from 53 to 27 million. In addition, 34 other countries, including China, may see declines of up to 50 percent.
Beyond sheer numbers, the researchers emphasize an aging society and slower overall growth. An aging population places growing pressure on social security and health systems and could alter the reach of government programs and tax bases.
Africa’s population surge
Sub-Saharan Africa is projected to continue its rise, potentially tripling over the century—from about 1.03 billion in 2017 to around 3.07 billion in 2100. North Africa and the Middle East stand as the only other region expected to surpass its 2017 population by 2100, reaching an estimated 978 million from about 600 million.
As fertility remains higher for longer, Africa’s share of the world’s population could grow substantially. By century’s end, researchers suggest roughly half of all people may reside in Africa, a shift that holds wide implications for global economics and development.
Global aging and economy
The study also foresees dramatic aging of the world’s age structure as fertility declines and life expectancy increases. By 2100, about 2.37 billion people could be aged 65 and over, up from 1.7 billion under age 20. The number of people over 80 could rise sixfold, from 141 million to 866 million, while the number of children under five may fall by more than 40 percent, from 681 million to 401 million.
These shifts indicate a smaller working-age population in major economies, including India and China, which could slow economic growth and reshape global power dynamics.
The authors warn that a shrinking workforce will challenge economic expansion and place a heavier burden on health and social support systems as the population ages.
Migration as a counterforce
The researchers suggest that immigration, alongside adaptable policy measures, could help maintain population size and support economic momentum even as fertility falls. “If more people die than are born, the population will decrease. The only way to counter this is immigration,” Murray noted.
While the report acknowledges potential positive environmental effects from a smaller population, an aging demographic will bring its own set of economic and social challenges.
The study underscores the difficulty of reorganizing societies and economies around an inverted age structure, calling for proactive thinking on how to adapt tax systems, healthcare, and social services to the new reality.
Reference work: https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(20)30677-2/fulltext
…our discussion continues in the broader discourse on demographic futures.
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