Explain projected 21st century population change and the policies governments use to manage growth, decline and ageing

What this dot point is asking

QCAA wants you to explain how population change is projected into the twenty-first century and how governments respond with policy. This builds on the demographic transition: now you look forward and at intervention. The command word "explain" means you set out how projections are made and why populations are heading toward growth, decline or ageing, then explain how policies aim to change that trajectory and with what effect. Strong answers distinguish a projection from a prediction, name real policies, and judge their effectiveness with evidence rather than assuming policy simply works.

The answer

How projections are made

A population projection estimates a future population by taking the current age and sex structure and applying assumptions about fertility, mortality and migration. Because those assumptions are uncertain, projections are usually given as a range: a high, medium and low scenario. A projection is not a prediction of what will happen but a calculation of what would happen if the assumptions hold. The current age structure carries enormous weight: a youthful population has built-in growth (demographic momentum) even if fertility falls, while an old population has built-in decline.

The twenty-first century outlook

Global population, around eight billion, is projected to keep growing for several decades before levelling off and possibly declining late in the century. The pattern is highly uneven. Almost all future growth is projected for sub-Saharan Africa and parts of South Asia, where populations remain youthful and fertility is still relatively high. In contrast, much of Europe and East Asia faces population decline and rapid ageing as fertility sits well below replacement level. The replacement level is about 2.1 children per woman; below it a population eventually shrinks without migration.

Ageing as the dominant challenge

For developed countries the defining twenty-first century issue is ageing: a rising share of older people and a shrinking working-age population. This raises the aged dependency ratio, pressures pensions and health systems, and can slow economic growth as the workforce contracts. Japan is the clearest case, with a shrinking, rapidly ageing population. Australia is ageing more slowly, cushioned by migration.

Population policies

Governments use policy to influence population trajectories:

• Antinatalist policies aim to lower birth rates. China's former one-child policy is the best-known example; it slowed growth but contributed to a skewed sex ratio and now a rapidly ageing, shrinking population, which is why it was abandoned.
• Pronatalist policies aim to raise birth rates through baby bonuses, parental leave, subsidised childcare and family payments. France and parts of Scandinavia use generous family support; Australia has used measures such as the former baby bonus and paid parental leave.
• Migration policies manage numbers, skills and ageing. Countries with low fertility, including Australia, use immigration to sustain the workforce, fill skill shortages and slow ageing.

Judging effectiveness

Policy effects are often weaker and slower than intended. Pronatalist incentives rarely lift fertility far, because the cost and lifestyle factors behind low fertility are large. Antinatalist policies can overshoot and create long-term ageing problems. Migration can offset ageing quickly but raises housing, infrastructure and social questions. Strong answers weigh a policy against its actual outcomes and side effects rather than assuming it achieves its aim.

Examples in context

Example 1. China. The one-child policy slowed growth but produced a rapidly ageing, now shrinking population and a skewed sex ratio, leading to its reversal and new pronatalist measures with limited effect so far.

Example 2. Japan. Sustained below-replacement fertility and limited migration produce projected long-term population decline and severe ageing, pressuring its pension and health systems.

Example 3. Australia. Below-replacement fertility offset by high net migration keeps the population growing and ageing slowly, while raising housing and infrastructure pressure in growth regions.