Demographic Futures

— aging, migration, and fertility, honestly measured

Population isn’t a “birth dearth” horror story or a “population bomb” story — it’s a set of measured trends that keep surprising even the demographers who study them for a living. This page reports the real UN and Statistics Canada numbers, dated, and names where forecasters have been caught off guard.

What’s actually happening

The United Nations’ 2024 population projection expects world population — 8.2 billion in 2024 — to peak at just under 10.3 billion around the mid-2080s, then ease slightly to about 10.2 billion by 2100. This is the third UN revision in a row to move the peak earlier and lower: the 2019 revision showed growth continuing with no peak in sight; the 2022 revision was the first to show any peak at all. The UN states this as an 80% likelihood, not a certainty, with the actual peak landing anywhere between the mid-2060s and 2100.

Global fertility fell from 4.84 children per woman in 1950 to 2.23 in 2021, and is forecast to reach 1.59 by 2100 (a March 2024 study). What has surprised demographers isn’t the direction — falling fertility as countries develop is a century-old, well-understood pattern — it’s the speed. South Korea is the sharpest recent miss on record: UN demographers projected roughly 350,000 births for 2023; the actual figure came in around 230,000, a miss of about a third. But the surprises now run in both directions: South Korea’s fertility rate rose for a second consecutive year in 2025, to 0.80, from 0.75 in 2024 and 0.72 in 2023 — 254,500 births, the most since 2010.

Canada’s own population fell for three consecutive quarters — the third quarter of 2025 through the first quarter of 2026 — the first such run on record, landing at 41,417,056 people as of April 1, 2026. The direct cause is a federal policy decision, not a demographic accident: Canada cut its immigration targets twice within about 13 months, first in October 2024 (cutting the annual permanent-resident target from 500,000 to a declining path) and again in the 2026–2028 Immigration Levels Plan, which also sharply cut planned temporary-resident arrivals, from 673,650 in 2025 to 385,000 in 2026.

Countries that industrialize later are aging faster, not just later, than the countries that went first. Japan took 24 years to go from an “aging” society (7% of population 65 or older) to an “aged” society (14%), 1970–1994. South Korea did the same transition in 17 years and crossed into “super-aged” status (20%) on December 23, 2024 — just 7 years after “aged.”

Where credible people think it’s heading

Even serious, well-resourced demographic modelling groups disagree substantially with each other on regional projections. A 2020 study from a separate major research group projected a global population peak in 2064 at 9.7 billion — twenty years earlier and up to a billion people lower than the UN’s own figures — with the gap traced specifically to a steeper assumed fertility decline in sub-Saharan Africa. That region is itself projected to account for roughly 1 in every 2 children born on the planet by 2100, even as fertility in East Asia has already collapsed below 1 child per woman in South Korea and China’s population shrinks outright — the same planet, on two very different demographic paths at once.

Estimates of how many people will be displaced by climate change by 2050 span an enormous range — from roughly 25 million at the low end to figures as high as 1 billion at the high end. A widely repeated “1 billion climate migrants” figure is, on inspection, a bundled number: only about 250 million of that billion is attributed to climate phenomena specifically, with the rest coming from conflict and general development-project displacement lumped under the same headline. The World Bank’s own modelling puts the more defensible ceiling at up to 216 million people internally displaced within their own countries by 2050.

What’s honestly uncertain

Demographic forecasting is genuinely one of the better-performing forecasting fields at the global level — historical UN world-population projections have generally landed within 1–2% of what actually happened — but genuinely weaker at the country or regional level, where projections have repeatedly missed, as both Canada’s recent contraction and South Korea’s fertility rebound illustrate live. Whether medicine can meaningfully extend maximum human lifespan — sometimes called “longevity escape velocity” — remains a live, credentialed dispute: named proponents argue medical progress could eventually add life-years faster than aging takes them away, while the most direct rebuttal calculates that reaching a life expectancy of 110 would require roughly 70% of women surviving to age 100, against about 5% today — a mathematically extreme jump the rebuttal calls implausible absent breakthroughs that don’t yet exist.

Why it matters for Toronto

Ontario’s own population growth projections were revised down after the federal immigration cuts above: the province’s Ministry of Finance now projects Ontario reaching roughly 20.5 million people by 2051, with the Greater Toronto Area growing from 7.7 million (2024) to about 9.4 million — a markedly slower path than an earlier 2024 provincial report had projected. Toronto’s own recent growth already shows this tension: the Toronto census area hit a record single-year population gain in the 12 months to July 2024 (up 268,911 people, +3.9%), driven overwhelmingly by non-permanent residents, even as the region kept losing residents to the rest of Ontario at the same time — a net outflow of 69,522 people in that same period. What young people themselves report wanting cuts against a simple “young people don’t want kids” reading: Statistics Canada’s own survey found the share of Canadians aged 15–49 intending to have biological children rose from 41% in 2021 to 46% in 2024, with the increase sharpest among the youngest respondents.