Sabtu, 18 Juni 2011

Population aging

One of the major consequences of the transition to low fertility is the aging of the population. Indeed, sustained fertility reductions lead over time to populations where the proportion of children declines while that of adults raises, especially that of adults at older ages. Following the usual definition of children as persons aged 0 to 14, elderly persons as those aged 60 years or over, and using the term adults from now on to refer only to persons aged 15 to 59, in 2000, 30% of the world’s population was constituted by children, 60% by adults and 10% by elderly persons. According to the medium variant, it is expected that by 2050 the proportion of the elderly will more than double, reaching 21%, that of children will be reduced by approximately one-third, reaching also 21%, and that of adults will remain largely unchanged, at 58% (Table 5.11). This changing distribution of the population by age is brought about by major changes in the rate of growth of the populations of children and the elderly (Fig. 5.5). Thus, whereas the growth rate of children declined from about 2.5% per year in the 1950s to nearly 0.4% per year in 1995–2000 and is expected to stay below that level until 2050, the growth rate of the elderly has been consistently high, varying largely between 2% and 2.5% annually since 1960, and is expected to increase even further over the period 2000–2030 to remain above 2.5% per year before declining to 1.6% per year in 2045–2050. The expected high rates of growth of the elderly population will result in more than a threefold increase in their numbers between 2000 and 2050, from 0.6 billion to nearly 2 billion, so that whereas in 2000 there were nearly three children for every elderly person, by 2050 there will be just one child per elderly person.
Because the process of population aging started earlier in the more-developed regions than in the rest of the world, their age distribution in 2000 is similar to the one expected at the world level for 2050. Indeed, as of 2000, the more-developed regions already had as many elderly persons as the number of children, and each of those

Table 5.11
Age composition of the population by broad age group, major area and region, medium variant, 2000 and 2050
Major area 2000 2050
0–14 15–59 60 0–14 15–59 60
Population (thousands)
World 1815 3636 606 1955 5404 1964
More-developed regions 218 742 231 183 603 395
Less-developed regions 1597 2894 374 1771 4801 1569
Least-developed countries 284 342 32 533 1123 173
Africa 338 415 40 559 1236 205
Asia 1111 2240 322 1061 3141 1227
Latin America and the Caribbean 164 314 41 161 463 181
Northern America 67 196 51 80 238 119
Europe 127 453 147 84 298 221
Oceania 8 19 4 9 27 11
World 30.0 60.0 10.0 21.0 58.0 21.1
More-developed regions 18.3 62.3 19.4 15.5 51.0 33.5
Less-developed regions 32.8 59.5 7.7 21.8 59.0 19.3
Least-developed countries 43.1 52.0 4.9 29.1 61.4 9.5
Africa 42.6 52.3 5.1 28.0 61.8 10.2
Asia 30.2 61.0 8.8 19.5 57.9 22.6
Latin America and the Caribbean 31.5 60.5 8.0 20.0 57.5 22.5
Northern America 21.5 62.3 16.2 18.3 54.5 27.2
Europe 17.5 62.3 20.3 13.9 49.4 36.6
Oceania 25.4 61.2 13.4 19.4 57.3 23.3
                                                                                                                                                                    0–14 15–59 Total
Figure 5.5
Growth rates of the different age groups at the world level, 1950–2050.

Table 5.12
Median age of the population for the world and major areas, by projection variant,
1950, 2000, and 2050
Major area or region 1950 2000 2050
High Medium Low
World 23.6 26.5 31.9 36.2 41.5
More-developed regions 28.6 37.4 42.2 46.4 50.3
Less-developed regions 21.4 24.3 30.8 35.0 40.2
Least-developed countries 19.5 18.2 24.0 26.5 29.5
Africa 19.0 18.4 24.8 27.4 30.5
Asia 22.0 26.2 33.4 38.3 44.2
Latin America and the Caribbean 20.1 24.4 32.6 37.8 44.4
Northern America 29.8 35.6 36.5 41.0 45.4
Europe 29.2 37.7 45.9 49.5 52.7
Oceania 27.9 30.9 34.6 38.1 41.7
Source: United Nations (2001a).

groups accounted for about a fifth of the population (actually, children were less numerous than the elderly). But aging in the more-developed regions is continuing. The maintenance of low fertility over the foreseeable future produces a population in 2050 where the elderly are expected to constitute a third of the population and children will account for only one in every seven persons. In fact, because fertility has already been very low in the more-developed regions for some time, the proportion of children is not expected to decline as much (from 18% in 2000 to 15% in 2050) as the adult population (from 62% in 2000 to 51% in 2050). That is, the population of more- developed regions is already entering the advanced stages of the aging process as the population of adults itself becomes considerably older. Another way to gauge the effects of population aging is to consider the median age of the population, that is, the age that divides the population into two equal halves. For the more developed regions, the median age rose from 29 years in 1950 to 37 years in 2000 and is expected to reach 46 years in the medium variant (Table 5.12). Aging would be more pronounced if fertility were to remain even lower, so that the low variant produces a population with a median age of 50 years, but even the higher fertility of the high variant would lead to substantial further rises in the median age which would be above 42 years in 2050.
Population aging is also expected in the less-developed regions as a whole, whose median age is expected to rise from 24 years in 2000 to between 31 and 40 years in 2050, with the medium variant producing a median age of 35 years. According to the medium variant, the elderly population in the less-developed regions would increase fourfold during 2000–2050, rising from 0.4 billion to nearly 1.6 billion, whereas the number of children would remain largely unchanged, passing from 1.6 billion to 1.8 billion. By the end of the projection period the less-developed regions would still have 58% of their population in the adult ages, with about a fifth of the population in each of the other two categories. Among the less-developed regions, the group of least-developed countries is expected to experience a more moderate aging, with the median age rising from 18 years in 2000 to between 24 and 30 years by 2050 (the medium variant produces a median age of 27 years). Nevertheless, in the medium variant the elderly population of the least-developed countries increases fivefold during 2000–2050, rising from 32 million to 172 million, and its share of the population nearly doubles, passing from 4.9% to 9.5%. Yet, by 2050 the least-developed countries will still have about three children for each elderly person, approximating therefore the age distribution of the less-developed regions of today.
At the level of major areas, Europe is expected to have the most aged population by 2050, whereas Africa will have the least aged. The median age of Europe’s population is expected to be between 46 and 53 years in 2050, with a medium variant value of approximately 50 years. By that time, nearly 37% of the population is expected to be aged 60 or over and slight less than half is expected to be aged 15–59. Children will account for just 14% of the population and the elderly will outnumber children nearly 3 to 1. In Africa, in contrast, the number of children is expected to be nearly double that of the elderly, and the latter will likely constitute just 10% of the population. The median age in Africa is expected to rise considerably, but starting at 18 in 2000 will at most rise to 30 years by 2050, being more likely to remain in the 20s (24 is projected under the high variant and 27 under the medium variant).
All other major areas are expected to have similar age distributions in 2050, with about 22% of the population being aged 60 or over, about 19% being children and 57% being adults aged 15–59. Northern America will have a slightly more aged population than the other major areas, with a median age of 41 years in 2050 according to the medium variant, rather than the 38 years expected for Asia, Latin America and the Caribbean, and Oceania. However, the convergence of the age distributions of Asia and Latin America and the Caribbean, in particular, to that of Northern America is the result of the very rapid aging of the populations of those two major areas. Indeed, as of 2000 both Asia and Latin America and the Caribbean had a considerably younger population than that of Northern America: their proportion of elderly persons was nearly half of that in Northern America and their median ages were about ten years lower than that of Northern America. The rapid reductions of fertility projected for Asia and Latin America and the Caribbean, which are largely based on the very substantial fertility reductions already experienced by some of the largest countries in those continents, are responsible for accelerating the aging of their population. That is, these developing regions will have less time to adapt to the economic and social implications of an aging population and need to act early to ensure that their societies are able to cope with the added demands for services, health care and social security associated with an aging population. The problem will be particularly acute in Asia, where the number of elderly persons is expected to rise fourfold during 2000–2050, so that by the end of the period Asia will have by far the largest elderly population in the world (1.2 billion), accounting for six out of every ten elderly persons in the world at that time. Furthermore, most of the elderly will be concentrated in the populous countries of Asia, especially in China (437 million), India (324 million), Indonesia (70 million), Japan (46 million), Bangladesh and Pakistan (each with 43 million). In Latin America, Brazil and Mexico will also have large populations of elderly persons: 59 million in Brazil and 36 million in Mexico. Although the more-developed countries will have more aged populations than most

Table 5.13
Countries with the highest and the lowest median ages, 1950, 2000, and 2050,
medium variant
Country or area 1950 Country or area 2000 Country or area 2050
1 Austria 35.80 1 Japan 41.22 Spain 55.21
2 Channel Islands 35.73 2 Italy 40.19 Slovenia 54.10
3 Belgium 35.55 3 Switzerland 40.18 Italy 54.08
4 Germany 35.37 4 Germany 40.06 Austria 53.70
5 Luxembourg 35.00 5 Sweden 39.70 Armenia 53.45
6 United Kingdom 34.63 6 Finland 39.43 Japan 53.14
7 France 34.51 7 Bulgaria 39.14 Czech Republic 52.37
8 Sweden 34.26 8 Belgium 39.13 Greece 52.32
9 Switzerland 33.33 9 Greece 39.12 Switzerland 52.03
1 Occupied Palestinian Terr. 17.19 1 Benin 16.58 Malawi 23.71
2 Malawi 17.12 2 Zambia 16.55 Burundi 23.25
3 Iraq 17.04 3 Burundi 16.03 Mali 22.95
4 Rwanda 16.97 4 Somalia 15.97 Liberia 22.92
5 United Rep. of Tanzania 16.94 5 Angola 15.88 Burkina Faso 22.75
6 Vanuatu 16.78 6 Democratic Rep.  15.58 Uganda 22.11
of the Congo
7 Botswana 16.78 7 Burkina Faso 15.56 Somalia 21.54
8 Fiji 16.58 8 Uganda 15.36 Angola 21.23
9 Samoa 16.56 9 Niger 15.06 Yemen 21.10
10 Djibouti 16.53 10 Yemen 14.97 Niger 20.39
Source: United Nations (2001a).

developing countries, the largest numbers of elderly persons will be increasingly concentrated in the developing world.
To conclude this analysis of the dynamics of population aging, let us consider the countries that have had or are expected to have the “oldest” and the “youngest” populations in the world. Table 5.13 shows the list of countries with the highest and lowest median ages in 1950, 2000, and 2050. Over the course of that century, the median age of the oldest population has been rising steadily and that trend is expected to continue, so that the highest median age will likely pass from 36 years in Austria in 1950, to 41 years in Japan in 2000 and to a remarkably high 55 years in Spain in 2050. In contrast, the median age of the youngest population declined from 1950 to 2000 as a result of reductions in mortality and the consequent increases in the proportions of surviving children. Thus, the lowest median age declined from 16.5 years in Djibouti in 1950 to a remarkably low 15 years in Yemen in 2000. However, in future, signs of population aging are expected even in countries whose fertility is expected to decline at a slower pace. Indeed, by 2050 the lowest median age is expected to be 20 years in Niger, a full five years higher than the lowest median age in 2000. For Yemen itself, the median age is expected to rise by seven years, reaching 21 years by 2050. Consequently, by the middle of this century countries will vary significantly in terms of the stage they are likely to have reached in the transition to an older population. Very young populations, such as those expected in countries like Angola, Niger, Uganda, or Yemen, to name just a few, will coexist with very aged populations, such as those of Austria, Italy, Japan, or Spain. Diversity in the dynamics of population growth is at the root of such a wide variation of outcomes and implies that the average trends observed at the world level are not necessarily representative of the experience of many of the countries of the world.


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