Population ageing

Population ageing is an overall change in the ages of a population. This can typically be summarised in a single parameter as an increase in the median age. Causes are a long-term decline in fertility rates and a decline in mortality rates. Most countries now have declining mortality rates and an ageing population: trends that emerged first in developed countries but are now also seen in virtually all developing countries. In most developed countries, population ageing started in the late 19th century. By the late 20th century, the world population as a whole was also ageing. The proportion of people aged 65 and above accounts for 6% of the total population. This reflects a historic overall decline in the world's average fertility rate. That is the case for every country in the world except the 18 countries designated as "demographic outliers" by the United Nations. The aged population is currently at its highest level in human history. The UN projects that the population will age faster in the 21st century than in the 20th. The number of people aged 60 years and over has tripled since 1950; it reached 600 million in 2000 and surpassed 700 million in 2006. It is projected that the combined senior and geriatric population will reach 2.1 billion by 2050. Countries vary significantly in terms of the degree and pace of ageing, and the UN expects populations that began ageing later will have less time to respond to its implications. Policy interventions include preventative strategies that increase the size of the young, working-age population, as well as adaptive measures to make overarching systems compatible with a new demographic future.

Overview

Population ageing is a shift in the distribution of a country's population towards older ages and 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 composed of the elderly. Population ageing is widespread across the world and is most advanced in the most highly developed countries, but it is growing faster in less developed regions, which means that older persons will be increasingly concentrated in the less developed regions of the world. The Oxford Institute of Population Ageing, however, concluded that population ageing has slowed considerably in Europe and will have the greatest future impact in Asia, especially since Asia is in stage five (very low birth rate and low death rate) of the demographic transition model. 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 28 in 1950 to 40 in 2010 and is forecast to rise to 44 by 2050. The corresponding figures for the world as a whole are 24 in 1950, 29 in 2010, and 36 in 2050. For the less developed regions, the median age will go from 26 in 2010 to 35 in 2050. Population ageing arises from two, possibly related, demographic effects: increasing longevity and declining fertility. 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. Of the two forces, declining fertility now contributes to most of the population ageing in the world. More specifically, the large decline in the overall fertility rate over the last half-century 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 will. The rate at which the population ages is likely to increase over the next three decades; however, few countries know whether their older population are living the extra years of life in good or poor health. A "compression of morbidity" would imply reduced disability in old age, but an expansion would see an increase in poor health with increased longevity. Another option has been posed for a situation of "dynamic equilibrium." That is crucial information for governments if the limits of lifespan continue to increase indefinitely, as some researchers believe. The World Health Organization's suite of household health studies is working to provide the needed health and well-being evidence, such as the World Health Survey, and the Study on Global Ageing and Adult Health (SAGE). The surveys cover 308,000 respondents aged at least 18 and 81,000 aged at least 50 from 70 countries. The Global Ageing Survey, directed by George Leeson, explores attitudes, expectations, and behaviours towards later life and retirement. It covers 44,000 people aged 40–80 in 24 countries around the world. It has revealed that many people are now fully aware of the ageing of the world's population and its implications for their lives and those of their children and grandchildren. Canada has the highest per capita immigration rate in the world, perhaps partly to counter population ageing. However the C. D. Howe Institute, a conservative think tank, has suggested that immigration cannot be used as a viable means to counter population ageing. That conclusion is also seen in the work of other scholars. The demographers Peter McDonald and Rebecca Kippen commented, "As 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."

Around the world

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