Population ageing

Geography glossary

Also called: Greying population, Ageing society · Topic: World Population: Distribution, Density, Growth and Migration · NCERT: Beyond NCERT

Meaning

Population ageing (also called a greying population or an ageing society) is a rise in the share of old people in a population, because fewer babies are born and people live longer. It matters because it changes how many people work and how many depend on them. This affects pensions, health care, jobs and migration across the world.

Explanation

How it forms (cause → process → result)

  • Cause 1: fewer births (falling fertility).
  • Fertility means births. When families have fewer children, there are fewer young people each year.

  • Worldwide, women in 2024 had on average one child fewer than in 1990 [1].

  • Cause 2: fewer deaths (falling mortality).

  • Better sanitation and health care mean people live longer.

  • Global life expectancy (the average number of years a person is expected to live) was 73.3 years in 2024, up from 70.9 years during the COVID-19 pandemic [1].

  • Result: the population gets older.

  • There are fewer children at the bottom and more old people at the top.
  • The share of people aged 65 and over rises.

Its place in demographic transition theory

  • Demographic transition theory says a society moves from high births and high deaths to low births and low deaths as it becomes urban, industrial and literate.
  • Ageing is what happens at the end of this journey:
  • Stage 4 (low stationary): births and deaths are both low. Old people form a larger share.

  • Stage 5 (declining): births fall below deaths, so the population shrinks. Deaths are low but start to rise, because so many people are old.

  • Replacement level is 2.1 births per woman. This is the number of births each generation needs to replace itself.

  • When fertility stays below 2.1 for a long time, each new generation is smaller than the one before, so the population ages.
  • In more than half of all countries, fertility is now below 2.1 [1].
  • Nearly one-fifth of countries have "ultra-low" fertility, meaning fewer than 1.4 births per woman (2024) [1].

How it shows on a population pyramid

  • A population pyramid (age-sex pyramid) is a bar graph of people by age group. Males are on the left, females on the right, and the youngest are at the bottom.
  • An ageing population has a constrictive pyramid:
  • It has a narrow base, because few children are born.
  • It has a wide middle and top, because many adults live into old age.

  • This shape belongs to stages 4-5. Examples: Japan, Italy, South Korea.

  • By contrast, an expansive pyramid (wide base, narrow top) shows a young, fast-growing population in stage 2.

The global outlook (UN World Population Prospects 2024)

  • By the mid-2030s, people aged 80 and over will outnumber infants under 1 [1].
  • By the late 2070s, people aged 65 and over will outnumber children under 18 [1].
  • 63 countries and areas, including China, Germany, Japan and Russia, had already reached their highest population by 2024 [1].

  • These countries are expected to shrink by about 14% over the next 30 years [1].

  • World population was 8.2 billion in 2024. It is expected to peak at about 10.3 billion in the mid-2080s and fall slightly to 10.2 billion by 2100 [1].

Where it occurs

  • Japan (East Asia): the oldest society. About 30% of its people are 65 or older. It is a stage 5 (declining) country.
  • Italy (Southern Europe) and South Korea (East Asia): come after Japan among the fastest-ageing societies. Both have constrictive pyramids.
  • China, Germany and Russia: among the 63 countries whose population had already peaked by 2024 [1]. China is also placed in stage 5.
  • UK and USA: stage 4 countries with stationary (bell or column) pyramids. They are older, but births and deaths are still roughly balanced.
  • India: not yet an ageing society. Its pyramid has a narrowing base and a bulge in the working ages. It is moving from expansive towards stationary and is in its demographic dividend window. Ageing is the stage that comes after this window.
  • The opposite case: Niger, Chad and much of sub-Saharan Africa are young, stage 2 countries. Nine countries will double their population between 2024 and 2054 [1].

Don't confuse with

  • Youth bulge: a large share of young people aged 15-24 or 15-29 (for example, sub-Saharan Africa, Pakistan, Afghanistan). It comes from late stage 2 or early stage 3. Ageing is the reverse: the share of old people rises, in stages 4-5.
  • Population decline (stage 5): decline means the total number of people falls because births are below deaths. Ageing means the share of old people rises. A country can age while its population is still growing, as in stage 4 countries such as the UK and USA.
  • Demographic dividend: extra economic growth when a large working-age group has jobs and few dependants. This is the window before ageing. Ageing closes it, because the number of dependent old people grows.
  • Expansive vs constrictive pyramid: an expansive pyramid (wide base) means a young population in stage 2. A constrictive pyramid (narrow base, wide top) means an ageing population in stages 4-5.

Prelims Hooks

  • Ageing has two causes working together: falling fertility (fewer births) and falling mortality (longer lives). Lower deaths on their own do not cause ageing.
  • Japan is the oldest society, with about 30% of people aged 65+, followed by Italy and South Korea. All three have constrictive pyramids.
  • UN WPP 2024: people 80+ will outnumber infants under 1 by the mid-2030s, and people 65+ will outnumber children under 18 by the late 2070s [1]. Know which milestone comes first.
  • Global life expectancy: 73.3 years (2024), up from 70.9 years during COVID-19 [1].
  • Replacement level = 2.1; ultra-low fertility = below 1.4, found in nearly one-fifth of countries (2024) [1].
  • Trap: 63 countries, including China, Germany, Japan and Russia, have already peaked [1]. India is not one of them. India is in its demographic dividend window.

Mains Points

  • Economic and social effects of ageing (GS-I):
  • Fewer workers have to support more old people, so pension and health care costs rise.

  • Shrinking countries need pensions, care for old people, automation and immigration (Japan, Italy, South Korea).

  • Ageing changes world migration patterns:

  • Fast-ageing countries will depend more on migrants from younger countries, such as those in sub-Saharan Africa.

  • This links the demographic transition to world migration flows. With 63 countries already past their peak [1], the pull of these countries on migrants will grow.

  • A lesson for India:

  • India is in its demographic dividend window now, but its narrowing base shows that ageing will follow.
  • It must give its young people skills and jobs, and build health care and old-age security, before the window closes.
  • The theory also has limits here: it cannot say how far fertility will fall below 2.1, as in the 2024 ultra-low fertility countries [1].

Related concepts

Read more

Sources

  1. 1UN projects world population to peak within this century (World Population Prospects 2024 press release, UN DESA)un.org · tier 2