The coming century is expected to bring major shifts in how the world is populated. In the near term, India is projected to overtake China as the most populous nation, while sub-Saharan Africa will see its numbers rise sharply. Countries like Spain could experience substantial declines, potentially dropping from about 46 million today to roughly 23 million. These trajectories are echoed across multiple studies that share a common finding: population growth will continue for several decades, followed by a gradual decrease in global numbers.
From an environmental standpoint, the overall footprint on the planet may lessen as populations stabilize, yet this shift will bring new challenges. Societies will need to adapt to caring for a growing elderly demographic and a smaller, aging workforce. A future with fewer working-age people could stress social support systems and public finances, demanding thoughtful policy responses.
Taking a long view, the world population could reach around 9.7 billion by 2064 and then decline toward about 8.8 billion by century’s end, a trend linked to higher education and broader access to family planning, according to Lancet studies and subsequent corroboration by researchers (Lancet, 2020; further analyses).
Research from the Institute for Health Metrics and Evaluation at the University of Washington School of Medicine indicates that by 2100, a majority of the world’s nations may not retain the fertility rate needed to maintain current populations. A visualization of country-by-country changes illustrates wide variations in demographic futures.
Several countries are expected to see population declines exceeding 50 percent, including Japan, Thailand, Italy, and Spain, according to these projections.
China’s population projection and broader shifts
In place of today’s vast numbers, Sub-Saharan Africa could see its population triple, creating a future where Africans constitute a significantly larger share of humanity by 2100. The Lancet study also foresees a substantial drop in the working-age cohort in countries like China, with potential implications for economic growth and social support systems. The scenario envisions China’s population shrinking to about 732 million, far lower than today’s level, reshaping global dynamics.
Migration may offset some declines, particularly in nations with higher immigration tolerance, including the United States, Canada, and Australia. A key insight from researchers is that immigration could help stabilize populations and support continued economic activity in low-fertility countries.
Speaking with CNN, Christopher Murray noted that the world has shifted from fearing too many people to confronting the challenge of having too few. The emphasis now is on managing this transition with policies that sustain growth while meeting social needs.
Population decline in Europe and Asia
By 2100, the most rapid decreases are projected for Asia and much of eastern and central Europe. Projections suggest Japan could fall from about 128 million in 2017 to roughly 60 million by 2100, while Thailand might slide from 71 million to about 35 million. Spain could drop from 46 million to 23 million, Italy from 61 to 31 million, Portugal from 11 to 5 million, and South Korea from 53 to 27 million. Across another 34 countries, including China, declines of up to 50 percent are anticipated. The aging of society, accompanied by a shrinking workforce, would challenge economic growth and shape new societal norms.
Experts emphasize that more people will reach retirement age, increasing demand for pensions and health care while contributing fewer workers to tax bases. This demographic shift could alter government priorities and fiscal sustainability.
Sub-Saharan Africa’s rising trajectory
Sub-Saharan Africa is projected to experience rapid population growth, potentially tripling its numbers over the century, rising from about 1.03 billion in 2017 to an estimated 3.07 billion by 2100. North Africa and the Middle East are the only other major region expected to surpass their 2017 population levels, with a forecast of 978 million versus 600 million.
Because fertility remains higher for longer in some regions, the share of the world’s population that is African could grow substantially. By the end of the century, it is possible that half of humanity might belong to Africa, reflecting profound shifts in regional demographics.
The world aging trend
Forecasts also highlight notable changes in global age structure as fertility declines and life expectancy rises. By 2100, roughly 2.37 billion people would be over 65, while about 1.7 billion would be under 20. The number of those over 80 could surge sixfold, rising from 141 million to around 866 million. Meanwhile, the number of children under five could fall by more than 40 percent, from 681 million in 2017 to 401 million in 2100.
Smaller working-age populations may slow economic growth in some large economies. The aging trend brings higher costs for health care and social support while altering patterns of consumption and investment.
Migration as a counterbalance
Researchers note that immigration could offset some demographic declines. Countries with open migration policies may better maintain population levels and sustain growth even as birth rates fall. As Murray explained, migration offers a direct mechanism to balance population dynamics when natural increase slows.
While the broader forecast acknowledges potential environmental benefits from fewer people in some contexts, it also flags the challenges of an aging society. The central question becomes how to redesign institutions, economies, and public services to operate effectively with a different age structure.
Reference: Lancet (2020) and subsequent analyses provide the basis for these projections, which describe how fertility, life expectancy, migration, and aging could reshape the global population matrix over the coming decades.
Note: The article avoids sharing a specific contact address or publication date. It relies on cited research throughout and presents the material in a manner suitable for readers seeking a clear, user-friendly overview of global demographic trends.