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Demographics: aging and population shifts
· Issue or flashpoint
FactTreaties, membership, measured data, events.
How birth rates, aging and migration are reshaping a world of about 8.2 billion people, projected to peak near 10.3 billion in the 2080s.
See it on the Geopolitics map →The picture
The world's fertility rate has fallen to about 2.2 children per woman, near the 2.1 replacement level. Japan, South Korea, China and most of Europe are well below it and aging: China's population has shrunk since 2022, and nearly 30% of Japanese are over 65. Africa is the exception: its roughly 1.5 billion people are projected to approach 2.5 billion by 2050, about a quarter of humanity. India passed China as most populous in 2023.
Why it matters
Aging strains pensions, health budgets, growth and military recruitment; young, fast-growing populations need jobs, or they fuel unrest and migration. Both shape power for decades.
Think of it like
Like a long-term lease schedule: you can see the vacancies coming decades ahead, but they are very hard to change.
Key facts and numbers
The UN's World Population Prospects 2024, national statistics offices, and census and birth-registration data; projections beyond 2050 carry wide uncertainty ranges.
What to watch
Why fertility is falling so fast even in middle-income countries, whether any policy reverses it, and whether AI and robots can offset shrinking workforces.
Inside this (2)
Connections (3)
▸Nigeria is Africa's population giant in Demographics: aging and population shiftsFact
The relationship
Nigeria has about 230 million people, a median age near 18 and roughly 4.5–5 children per woman. UN projections put it at roughly 360–375 million by 2050, among the world's most populous countries. That could supply a huge workforce, or, without enough jobs, deepen poverty, insecurity and emigration.
Since when and why
West Africa; Nigeria's last census was in 2006, and a new one keeps being postponed; the UN's World Population Prospects 2024 supplies current estimates.
How we know
UN population estimates and Nigeria's Demographic and Health Surveys; with no census since 2006, totals are estimates and contested.
What to watch
Whether fertility falls fast enough for a 'demographic dividend', the growth boost when workers outnumber dependents, as in East Asia; the decline so far is slow.
▸India is the most populous nation in Demographics: aging and population shiftsFact
The relationship
India passed China in 2023 as the most populous country, with about 1.46 billion people and a median age around 28. Its working-age population will keep growing into the 2040s, a potential 'demographic dividend', even though fertility has already fallen to about 2.0, below replacement.
Since when and why
UN estimates put the crossover in April 2023; southern states such as Kerala and Tamil Nadu already have low, European-style fertility, while northern states remain much younger.
How we know
UN World Population Prospects and India's National Family Health Survey; the last census was in 2011, so totals are estimates until the 2027 census.
What to watch
Whether India creates jobs for the roughly 8–10 million people entering the workforce each year, and how the 2027 census reshapes parliamentary seats between north and south.
▸South Korea's record-low fertility is the extreme case in Demographics: aging and population shiftsFact
The relationship
At about 0.8 children per woman, South Korea is furthest along a path many rich countries, and China, are following. At that rate each generation is about 40% the size of the one before. Its experience, from closing schools to shrinking army intake, previews what rapid aging means for economies and security.
Since when and why
Nationwide, sharpest in Seoul; below 1.0 since 2018, with a low of 0.72 in 2023 and about 0.80 in 2025.
How we know
Statistics Korea birth data and UN comparisons ranking it the world's lowest; the arithmetic of generational shrinkage is straightforward.
What to watch
Whether the small 2024–25 rebound lasts, and whether others, such as Taiwan and China, sink to similar levels, are open questions.