World Population in 2050: What We Can Actually Predict

About 9.7 billion — and most of those people have already been born

The UN's central projection puts world population at roughly 9.7 billion in 2050 — about 1.5 billion more than today. Almost everything about where those people will be is already determined. Most of them have already been born.

The 2050 picture

UN World Population Prospects, medium variant.

Why 2050 is more predictable than it sounds

Projections thirty years out are unusually reliable, for a reason that is easy to miss: everyone who will be 30 or older in 2050 is already alive.

Barring catastrophe, the size of those cohorts is essentially fixed. What remains uncertain is only how many children are born between now and then, and how mortality shifts. That is why demographers regard 2050 as reasonably firm while treating 2100 as genuinely speculative — by 2100, most of the population consists of people not yet born, whose numbers depend on fertility assumptions compounding over three generations.

Half of all growth, eight countries

Growth between now and 2050 is remarkably concentrated. More than half of the projected increase is expected to come from a handful of countries: India, Nigeria, Pakistan, the Democratic Republic of the Congo, Ethiopia, Tanzania, Egypt, and the Philippines.

Nigeria is the standout. On current trajectories it passes the United States to become the world's third most populous country before 2050, having been outside the top ten within living memory.

Meanwhile Europe's population is projected to be smaller in 2050 than today, and China's substantially so — potentially by more than 100 million. The redistribution is larger than the growth.

The doubling of old age

The single largest structural change is not the total — it is the age structure. The number of people over 65 is projected to roughly double, from about 830 million to 1.6 billion.

That is not a projection about birth rates. Those people are alive today and in their forties and fifties. Short of a mortality shock, the number is close to locked in, which makes it among the most reliable demographic forecasts available.

The consequences follow arithmetically: pension systems, healthcare demand, housing patterns, and labour supply all shift, and they shift in countries whose institutions were designed for a younger population. See population ageing for how different countries are responding.

Where the uncertainty actually lies

The UN publishes a range, and the range is wide enough to matter. The 2050 figure has a plausible spread of several hundred million; by 2100 the spread runs to billions.

Three things could move it:

• African fertility. If it falls faster than projected — as it did unexpectedly fast in parts of Asia and Latin America — the 2050 figure comes in lower.
• Mortality surprises. Pandemics, conflict, or breakthroughs in age-related disease all shift the total, in either direction.
• Sustained low fertility spreading. If the sub-1.0 fertility now seen in South Korea appears more widely, projections fall sharply.

What almost no scenario produces is runaway growth. The fertility decline is broad enough that the argument is now about how soon the curve turns, not whether it does. See when world population will peak.