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Population ageing

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Population ageing is a fundamental shift in the age distribution of a group of people. It occurs when a population moves toward older age groups. This change is usually measured by the median age. The median age is the middle value in a set of numbers. When the median age rises, the average age of the entire population increases. This process involves a decline in the proportion of children. Simultaneously, there is a rise in the proportion of elderly people.

Median age by country
Median age by country

Two main demographic forces drive this global change. The first is increasing longevity. Longevity refers to the length of time a person lives. As more people survive to older ages, the average age rises. The second force is declining fertility. Fertility is the rate at which babies are born. When fewer children are born, the number of young people decreases. Currently, declining fertility is the primary driver of ageing in most developed countries. These two forces work together to reshape how many people of each age exist.

Population by broad age group projected to 2100, OWID
Population by broad age group projected to 2100, OWID

This trend has moved through different stages across the globe. It began in developed countries during the late 19th century. By the late 20th century, the entire world population began to age. Today, almost every country is experiencing this shift. The United Nations notes that 18 countries are "demographic outliers." These are the only nations not following the global trend of ageing. While developed regions are most advanced, less developed regions are ageing even faster. This means older people will soon be more concentrated in developing areas.

Global Population-Pyramid-1950-to-2100
Global Population-Pyramid-1950-to-2100

The scale of this shift is visible in recent statistics. The number of people aged 60 and over has tripled since 1950. In the year 2000, this group reached 600 million people. By 2006, the number surpassed 700 million. Projections suggest the senior and geriatric population will reach 2.1 billion by 2050. In developed countries, the median age was 28 in 1950. By 2010, it had risen to 40. It is forecast to reach 44 by 2050.

Percentage of the World Population Over 65 - 1950-2050
Percentage of the World Population Over 65 - 1950-2050

Ageing creates significant economic challenges and opportunities. Older people often have higher personal savings than younger people. However, they tend to spend less on consumer goods. This can lead to lower interest rates and lower inflation. Some economists in Japan see benefits in this trend. They believe it may encourage automation and new technology. Conversely, ageing increases specific government costs. Health care is often the largest area of expenditure. As populations age, the cost of medical services may rise dramatically.

Dementia Prevalence in OECD
Dementia Prevalence in OECD

Social systems must also adapt to these changing numbers. Many countries use pension systems to support retired workers. These are often "defined benefit" systems. However, increased longevity can make these systems hard to sustain. Governments may face difficult choices regarding taxes. They might need to increase taxes on earnings or consumption. Some nations, like Canada, use immigration to help maintain the working-age population. Demographers suggest that very high levels of migration may be needed to keep population growth stable.

Percentage of the World Population Over 65 - 1950-2050
Percentage of the World Population Over 65 - 1950-2050

Global organizations are working to understand these transitions. The World Health Organization studies health and well-being through large surveys. For example, the SAGE study covers 81,000 people aged 50 or older. These studies help determine if people are living longer in good health. This concept is called the "compression of morbidity." This would mean people experience less disability in their later years. Understanding these patterns helps cities become more "age-friendly." This includes improving housing, transportation, and social participation for everyone.

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File:Global Population-Pyramid-1950-to-2100.jpg
Global Population-Pyramid-1950-to-2100.jpg
File:Population by broad age group projected to 2100, OWID.svg
Population by broad age group projected...
Median age by country.webp
File:Percentage of the World Population Over 65 - 1950-2050.png
Percentage of the World Population Over...
File:Dementia Prevalence in OECD.svg
Dementia Prevalence in OECD.svg
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