Population ageing
Encyclopedia
Population ageing or population aging (see English spelling differences
American and British English spelling differences
One of the ways in which American English and British English differ is in spelling.-Historical origins:In the early 18th century, English spelling was not standardized. Differences became noticeable after the publishing of influential dictionaries...

) occurs when the median
Median
In probability theory and statistics, a median is described as the numerical value separating the higher half of a sample, a population, or a probability distribution, from the lower half. The median of a finite list of numbers can be found by arranging all the observations from lowest value to...

 age of a country or region rises. This happens because of rising life expectancy
Life expectancy
Life expectancy is the expected number of years of life remaining at a given age. It is denoted by ex, which means the average number of subsequent years of life for someone now aged x, according to a particular mortality experience...

 or declining birth rate
Birth rate
Crude birth rate is the nativity or childbirths per 1,000 people per year . Another word used interchangeably with "birth rate" is "natality". When the crude birth rate is subtracted from the crude death rate, it reveals the rate of natural increase...

s. Excepting 18 countries termed 'demographic outliers' by the UN
United Nations
The United Nations is an international organization whose stated aims are facilitating cooperation in international law, international security, economic development, social progress, human rights, and achievement of world peace...

) this process is taking place in every country and region across the globe. In the entirety of recorded human history, the world has never seen as aged a population as currently exists globally. The UN predicts the rate of population aging in the 21st century will exceed that in the 20th. Countries vary significantly in terms of the degree, and the pace, of these changes, and the UN expects populations that began aging later to have less time to adapt to the many implications of these changes.

Overview

Population ageing is a shift in the distribution of a country's population towards older ages. This is usually reflected in an increase in the population's mean and median ages, a decline in the proportion of the population composed of children, and a rise in the proportion of the population that is elderly. Population ageing is widespread across the world. It is most advanced in the most highly developed countries. However the Oxford Institute of Population Ageing http://www.ageing.ox.ac.uk, one of the top institutions looking at global population ageing, has concluded that population ageing has slowed considerably in Europe and will have the greatest future impact in Asia, especially as Asia is in stage five of the demographic transition model
Demographic transition
The demographic transition model is the transition from high birth and death rates to low birth and death rates as a country develops from a pre-industrial to an industrialized economic system. The theory is based on an interpretation of demographic history developed in 1929 by the American...

.

Among the countries currently classified by the United Nations as more developed (with a total population of 1.2 billion in 2005), the overall median age rose from 29.0 in 1950 to 37.3 in 2000, and is forecast to rise to 45.5 by 2050. The corresponding figures for the world as a whole are 23.9 in 1950, 26.8 in 2000, and 37.8 in 2050. In Japan, one of the fastest ageing countries in the world, in 1950 there were 9.3 people under 20 for every person over 65. By 2025 this ratio is forecast to be 0.59 people under 20 for every person older than 65.

Population ageing arises from two (possibly related) demographic effects: increasing longevity
Longevity
The word "longevity" is sometimes used as a synonym for "life expectancy" in demography or known as "long life", especially when it concerns someone or something lasting longer than expected ....

 and declining fertility
Fertility
Fertility is the natural capability of producing offsprings. As a measure, "fertility rate" is the number of children born per couple, person or population. Fertility differs from fecundity, which is defined as the potential for reproduction...

. An increase in longevity raises the average age of the population by increasing the numbers of surviving older people. A decline in fertility reduces the number of babies, and as the effect continues, the numbers of younger people in general also reduce. A possible third factor is migration.

Of these two forces, it is declining fertility that is the largest contributor to population ageing in the world today. More specifically, it is the large decline in the overall fertility rate over the last half century that is primarily responsible for the population ageing in the world’s most developed countries. Because many developing countries are going through faster fertility transitions, they will experience even faster population ageing than the currently developed countries in the future.

The speed of population ageing is likely to increase over the next 3 decades, yet few countries have the evidence to determine if their growing older populations are living the extra years of life in good or poor health. A "compression of morbidity
Compression of morbidity
The compression of morbidity in public health is a hypothesis put forth by James Fries, professor of medicine at Stanford University School of Medicine...

" would imply reducing reduced disability in old age, whereas an expansion would see an increase in poor health with increased longevity. Another option has been posed for a situation of "dynamic equilibrium" (Manton, 1982). This is crucial information for governments if the limits of lifespan continue to increase indefinitely, as some researchers believe it will. . The World Health Organization
World Health Organization
The World Health Organization is a specialized agency of the United Nations that acts as a coordinating authority on international public health. Established on 7 April 1948, with headquarters in Geneva, Switzerland, the agency inherited the mandate and resources of its predecessor, the Health...

's suite of household health studies is working to provide the needed health and well-being evidence, including, for example the World Health Survey, and the Study on Global Ageing and Adult Health (SAGE)). These surveys cover 308,000 respondents aged 18+ years and 81,000 aged 50+ years from 70 countries.

The Global Ageing Survey, exploring attitudes, expectations and behaviours towards later life and retirement, directed by George Leeson, and covering 44,000 people aged 40–80 in 24 countries from across the globe has revealed that many people are now fully aware of the ageing of the world's population and the implications which this will have for their lives and the lives of their children and grandchildren.

Canada has the highest per capita immigration rate in the world, partly to counter population ageing. The C. D. Howe Institute
C. D. Howe Institute
The C.D. Howe Institute is a Canadian public policy think tank based in downtown Toronto, Ontario. Founded in 1958, the Institute publishes research and hosts conferences on a wide variety of issues in Canadian economic and social policy...

, a conservative think tank, has suggested that immigration cannot be used as a viable mean for countering population ageing. This conclusion is also seen in the work of other scholars. Demographers Peter McDonald and Rebecca Kippen comment, "[a]s fertility sinks further below replacement level, increasingly higher levels of annual net migration will be required to maintain a target of even zero population growth."

Ageing around the world

Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...

 and Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

 are the two regions where a significant number of countries face severe population ageing in the near future. In these regions within twenty years many countries will face a situation where the largest population cohort
Cohort (statistics)
In statistics and demography, a cohort is a group of subjects who have shared a particular time together during a particular time span . Cohorts may be tracked over extended periods in a cohort study. The cohort can be modified by censoring, i.e...

 will be those over 65 and average age will be approaching 50. The Oxford Institute of Ageing http://www.ageing.ox.ac.uk is an institution looking at global population ageing. Its research reveals that many of the views of global ageing are based on myths and that there will be considerable opportunities for the world as its population matures. The Institute's Director, Professor Sarah Harper
Sarah Harper
Sarah Harper is a British gerontologist. She achieved particular acclaim when she established Oxford's Institute of Ageing, and became the University of Oxford's first Professor of Gerontology. She holds the first Professorship of Gerontology at the University of Oxford...

 http://www.ageing.ox.ac.uk/people/sarah-harper highlights in her book Ageing Societies the implications for work, families, health, education and technology of the ageing of the world's population.

Most of the developed world (with the notable exception of the United States) now has sub-replacement fertility
Sub-replacement fertility
Sub-replacement fertility is a total fertility rate that leads to each new generation being less populous than the previous one in a given area. In developed countries sub-replacement fertility is any rate below approximately 2.1 children born per woman, but the threshold can be as high as 3.4...

 levels, and population growth now depends largely on immigration together with population momentum which arises from previous large generations now enjoying longer life expectancy.

Ageing, well-being and social policy

The economic effects of an ageing population are considerable. Older people have higher accumulated savings per head than younger people, but may be spending less on consumer goods. Depending on the age ranges at which the changes occur, an ageing population may thus result in lower interest rate
Interest rate
An interest rate is the rate at which interest is paid by a borrower for the use of money that they borrow from a lender. For example, a small company borrows capital from a bank to buy new assets for their business, and in return the lender receives interest at a predetermined interest rate for...

s and the economic benefits of lower inflation. Some economists (Japan) see advantages in such changes, notably the opportunity to progress automation and technological development without causing unemployment. They emphasize a shift from GDP to personal well-being.

However population ageing also increases some categories of expenditure, including some met from public finances. The largest area of expenditure in many countries is now health care
Health care
Health care is the diagnosis, treatment, and prevention of disease, illness, injury, and other physical and mental impairments in humans. Health care is delivered by practitioners in medicine, chiropractic, dentistry, nursing, pharmacy, allied health, and other care providers...

, whose cost is likely to increase dramatically as the population ages. This would present governments with hard choices between higher tax
Tax
To tax is to impose a financial charge or other levy upon a taxpayer by a state or the functional equivalent of a state such that failure to pay is punishable by law. Taxes are also imposed by many subnational entities...

es, including a possible reweighing of tax from earnings to consumption, and a reduced government role in providing health care.

The second largest expenditure of most governments is education
Education
Education in its broadest, general sense is the means through which the aims and habits of a group of people lives on from one generation to the next. Generally, it occurs through any experience that has a formative effect on the way one thinks, feels, or acts...

 and these expenses will tend to fall with an ageing population, especially as fewer young people would probably continue into tertiary education as they would be in demand as part of the work force.

Social security systems have also begun to experience problems. Earlier defined benefit pension system
Pension Benefit Guaranty Corporation
The Pension Benefit Guaranty Corporation is an independent agency of the United States government that was created by the Employee Retirement Income Security Act of 1974 to encourage the continuation and maintenance of voluntary private defined benefit pension plans, provide timely and...

s are experiencing sustainability problems due to the increased longevity. The extension of the pension period was not paired with an extension of the active labour period or a rise in pension contributions, resulting in a decline of replacement ratios. In recent years, many countries have adopted policies to strengthen the financial sustainability of pension systems, although the challenges regarding pension adequacy remain.

External links

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