Population ageing

Population ageing is primarily caused by two demographic shifts: a decline in fertility rates and an increase in life expectancy. When couples have fewer children, the base of the age pyramid narrows, while extended lifespans add more years at the top. The median age—the age that divides a population into two equal halves—is a key indicator; in 1950 the global median age was about 24, and by 2020 it had risen to 31. The pace of ageing varies greatly by region: Japan, Italy, and Germany are among the oldest countries, with median ages above 45, whereas many sub-Saharan African nations have median ages below 20.¹ Demographers also use the old-age dependency ratio (the number of people aged 65+ per 100 working-age adults) to gauge the economic burden of ageing.

The world is ageing at an unprecedented rate. According to the United Nations, the number of people aged 60 or over is expected to double from 1 billion in 2019 to 2.1 billion by 2050. In 2019, 9.1% of the global population was aged 65 or older; by 2050, that share is projected to reach 16%. East Asia and Europe are the most advanced in this transition, while Africa remains the youngest continent, though even there the number of older persons is growing in absolute terms. The COVID-19 pandemic had a temporary negative impact on life expectancy in many countries, but the long-term ageing trend is expected to resume.²

Population ageing strains public pension systems, healthcare services, and labor markets. As the share of retirees grows relative to workers, pay-as-you-go pension schemes face funding gaps, and healthcare costs rise due to the higher prevalence of chronic diseases among older adults.³ Governments have responded by raising retirement ages, encouraging immigration, and promoting 'active ageing' policies to keep older people in the workforce. However, ageing also creates opportunities: the 'silver economy'—goods and services for older consumers—is a growing market, and older workers bring experience and stability. The World Health Organization advocates for 'healthy ageing' to maximize functional ability in later life.⁴

Beyond the headline statistics, population ageing has subtle and surprising dimensions. For instance, the gender gap in life expectancy means that older populations are disproportionately female; in 2019, women outnumbered men by 137 million among those aged 60 and over. Ageing also affects geographic distribution—rural areas often age faster than cities as young people migrate to urban centers. In some countries, such as Japan, the phenomenon of 'kōreisha' (elderly) has led to innovations like robot caregivers and age-friendly urban design. Additionally, the demographic transition in developing countries is occurring at lower income levels than it did in the West, a phenomenon called 'getting old before getting rich,' which poses unique challenges for social protection systems.

Median age

The age that divides a population into two numerically equal groups.

Old-age dependency ratio

The number of people aged 65 and over per 100 people aged 15–64.

Fertility rate

The average number of children born to a woman over her lifetime.

Silver economy

The economic sector focused on goods and services for older adults.

Active ageing

Policies and practices that enable older people to participate in society and the workforce.