World: 5.1% more people than the UN expected in 1998 — mostly because more babies were born
The 1998 projection for 2023: 7.7B; the UN now estimates 8.09B, 393M more. The bars separate the sources of this gap.
More
A population projection is built from four parts: how many people live there at the start, how many will be born, how many will die and how many more will arrive than leave. The UN has since estimated each part anew, which shows where the projection went wrong. Here the total missed, mostly because of one part. 264M more babies were born than expected; the UN later put the 1995 population 92.5M higher; 40.2M fewer people died. The same projection assumed 2.35 children per woman for 2010–2015; the outcome was 2.58.
A bar is how much one part moved the total against the projection: right means more people than projected, left means fewer; the number is the size of the move. More births and fewer deaths add people; fewer births and more deaths take them away. “1995 population higher / lower”: the UN later estimated the population the projection started from differently from what it assumed then. The last bar is the total; the parts add up to it within a small residual.
- UN 1998 projection for 2023
7.7B
- UN 2024 estimate
8.09B
- Population in 1995: in the projection → estimated now
5.67B → 5.76B
- Births 1995–2023: assumed → estimated now
3.62B → 3.88B
- Deaths 1995–2023: assumed → estimated now
1.59B → 1.55B
- Net migration 1995–2023, arrivals minus departures: assumed → estimated now
0 → 0
- Residual of the calculation
−3.67M
The UN 1998 projection for 2023 against the UN 2024 estimate. The gap is split along the population balance: the 1995 population (estimated now minus the one the projection started from), then births, deaths and net migration over 1995–2023 (estimated now minus assumed; for deaths the other way round, since more deaths mean fewer people). Residual −3.67M: rounding and the five-year periods of older projections. Chosen: a projection of at least 8 years off by 4% or more, where one part made at least 45% of the gap.
Both the projection and the current figure are UN estimates: in countries without full registration of births and deaths they come from a model, not a count.
A question for this picture
Which of these could have been known when the projection was made?