Investigate global population change: the demographic transition model, population pyramids, ageing populations in developed countries, rapid growth in lower-income countries, urbanisation, and policy responses

Note: This page is part of the HSC Geography 11-12 (2022) syllabus content, first examined in HSC 2025. The legacy 2009 syllabus content is preserved as reference for older revision material in the sibling module folders.

What this dot point is asking

The Global sustainability focus area asks you to investigate how populations change over time, why patterns differ between countries, and what challenges arise for governments and societies. You need to apply the demographic transition model, read population pyramids, and evaluate named policy responses. Apply geographical concepts (scale, change, interconnection) and inquiry skills including the analysis of demographic data and visualisations.

The answer

Global population growth is slowing overall but is highly uneven. Some countries are experiencing rapid ageing and natural decline; others continue to grow rapidly. Urbanisation is reshaping where people live within every country. These patterns connect to economic development, climate vulnerability, and political stability.

The Demographic Transition Model (DTM)

The DTM is a five-stage conceptual model derived from the historical experience of European countries. It describes the relationship between crude birth rate, crude death rate and total population as a country develops.

• Stage 1 (pre-industrial). High birth rate, high death rate, low and fluctuating population. Few countries are in Stage 1 today.
• Stage 2 (early industrial). Death rate falls due to improved nutrition, sanitation and healthcare; birth rate remains high; rapid population growth. Many countries in Sub-Saharan Africa are in Stage 2 or transitioning to Stage 3.
• Stage 3 (late industrial / urbanising). Birth rate falls as education (especially of women), urbanisation and access to contraception spread; population still grows but more slowly. Many South and South-East Asian countries are in Stage 3.
• Stage 4 (post-industrial). Low birth rate, low death rate, stable or slow-growing population. Australia, the United States and much of Europe sit around Stage 4.
• Stage 5 (post-transition decline). Birth rate falls below death rate; natural decrease; ageing population. Japan, Italy, Germany, South Korea and several Eastern European countries are in Stage 5.

The DTM is a model: useful as a framework, but no country exactly follows it, and its historical reference points reflect European trajectories.

Population pyramids

A population pyramid plots age cohorts (typically in five-year bands) by sex. Its shape encodes the demographic situation:

• Expansive (broad base). High birth rate, high death rate or short life expectancy. Typical of Stage 2 countries (Niger, Uganda, Afghanistan).
• Constrictive (narrowing base). Falling birth rate, ageing population. Typical of Stage 4 to Stage 5 (Japan, Italy, Australia).
• Stationary. Roughly even cohort sizes; stable population.

A pyramid that bulges in the working-age cohorts indicates a demographic dividend (more workers per dependent). A top-heavy pyramid indicates an ageing dependency burden.

Ageing populations

In many high-income countries, life expectancy has risen and birth rates have fallen below the replacement level (approximately 2.1 children per woman). Implications include:

• Workforce shrinkage relative to retirees.
• Pension and healthcare cost growth as a share of GDP.
• Pressure on labour migration policy to maintain workforce.
• Spatial impacts including the depopulation of rural towns as young workers move to cities.

Japan is the most-cited example: its population peaked around 2010 and is declining; the share aged 65 and over is among the highest in the world. Italy, Germany and South Korea face similar dynamics.

Rapid-growth populations

Sub-Saharan Africa is projected to be the source of most of the world's population growth this century. Drivers include high fertility, falling child mortality, and a young population structure (population momentum). Implications include:

• Pressure on food, water, energy, education and health systems.
• Rapid urbanisation as people move to cities seeking jobs.
• Demographic dividend potential if education and employment expand fast enough.

Nigeria's population, the largest in Africa, is projected to continue growing significantly in coming decades.

Urbanisation

In recent decades the world has crossed the threshold where more than half of the global population lives in urban areas. By mid-century the urban share is projected to rise substantially further, with most growth in Asia and Africa. Urbanisation is both a driver (lower fertility in cities) and a consequence of demographic transition.

Policy responses

• Pro-natalist policies. Hungary, Singapore, South Korea and others offer financial incentives, childcare and parental leave to lift fertility. Results have been modest.
• Immigration. Australia, Canada and Germany use planned migration to supplement workforce growth and to support the dependency ratio.
• Family planning and education. India's National Family Planning Programme and similar programs across the developing world have contributed to falling fertility, alongside girls' education and women's labour-force participation.
• China's former one-child policy (in place from 1980; relaxed to two children in 2016 and three in 2021) is one of the most cited population policies. It is credited with reducing population growth but is also associated with skewed sex ratios at birth and an accelerated ageing trajectory.
• Retirement-age and pension reform. Many high-income countries are raising retirement ages.

Examples in context

Example 1. Australia's migration-driven demographic profile. Australia has below-replacement fertility but a growing population, sustained primarily by planned migration. The Australian Government's Migration Strategy sets annual permanent and temporary migration intakes. Migration shapes the age structure (most migrants are working-age), the spatial distribution (concentrated in Sydney, Melbourne and South-East Queensland), and the skills mix in the labour market. A strong response uses Australia to illustrate: how a Stage 4 country can avoid population decline through migration; the spatial concentration of migrants in major cities and its effect on housing and infrastructure; and the connection between demography and economic policy.

Example 2. Sub-Saharan Africa as the demographic frontier. Nigeria, the Democratic Republic of Congo, Ethiopia, Tanzania and Uganda are among the countries with the largest projected population increases this century. The combination of a youth bulge and rapid urbanisation creates both opportunity (demographic dividend if education and jobs expand) and risk (pressure on services, vulnerability to food and water stress). African Union Agenda 2063 and country-level National Development Plans address education, health and family planning. A strong response uses this region to illustrate the interconnection between demographic change, economic development and climate vulnerability, and the uneven global geography of population futures.

Try this

Q1. Describe the five stages of the Demographic Transition Model and name a country at each stage. [4 marks]

• Cue. Stage 1 (very few today; historical pre-industrial). Stage 2 (Niger, Uganda). Stage 3 (India, Indonesia). Stage 4 (United States, Australia). Stage 5 (Japan, Italy, Germany). Hedge with "approximately" where placement is debated.

Q2. Analyse two challenges faced by countries with rapidly ageing populations. [6 marks]

• Cue. Workforce shrinkage relative to retirees. Pension and healthcare cost growth. Rural depopulation. Pressure on immigration policy. Use Japan or Italy as named example.

Q3. Evaluate one population policy as a response to demographic change. [8 marks]

• Cue. Pick China's former one-child policy, Australia's planned migration program, Hungary's pro-natalist incentives, or India's family planning program. Strengths and limits. Connect to geographical concepts of scale (national policy in a global context) and change (the policy's intended demographic trajectory vs the observed outcome). Reach a calibrated judgement.