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United Nations Population Division 155 World Population Prospects: The 2000 Revision, Volume III: Analytical Report

V. POPULATION SIZE AND COMPOSITION

Since the appearance of human beings on Earth, no century has witnessed such a rapid and accel-erating population growth than the twentieth cen-tury. Indeed, before 1900, the world population grew slowly, if at all. Average growth rates rarely exceeded 0.1 per cent for most of the existence of humankind (Durand, 1977). At the global level, the rate of population growth departed signif i-cantly from zero only after 1750, when popula-tions in Europe began to experience a sizeable reduction in mortality. Although the decline in mortality was eventually followed by a reduction in fertility, during the period of transition from high to low mortality and then from high to low fertility, population growth accelerated. The de-veloped countries of today were the first to un-dergo these transitions and, as previous chapters have shown, the developing countries have ex-perienced most of these changes during the sec-ond half of the twentieth century. The effects of the changes on population growth are clear when one considers the timing of population increases. As illustrated in table V.1, the population of the world first surpassed the one billion mark at the beginning of the nineteenth century (at about 1804) when the population was growing at an an-nual rate of 0.5 per cent; it took more than a cen-tury for the population to double. By 1927, the

TABLE V.1. M ILESTONES IN WORLD P OPULATION

Type of data

World population in billions

Year when

reached

Number of years it took to increase

by one billion

Estimates .................... 1 1804 2 1927 123 3 1960 33 4 1974 14 5 1987 13 6 1999 12 Medium projection variant.................... 7 2012 13 8 2026 13 9 2043 17 9.3 2050

population had reached 2 billion and growth had accelerated to about 1 per cent per year. When the use of vaccines, antibiotics and insecticides be-came widespread in the 1950s, mortality began a rapid decline in the developing countries, with the result that the rate of population growth accele r-ated again. Consequently, the population doubled in 47 years, reaching 4 billion in 1974. Although fertility in the developing countries began to de-cline in the late 1960s, the world population had increased by another two billion by the end of the twentieth century.

World population growth reached a peak in

1965-1970, when the annual growth rate stood at 2 per cent. Since 1970, the growth rate has been declining (figure V.1) and it is estimated to be 1.2 per cent in 2000-2005. By the middle of the twenty-first century, the population of the world is projected to be growing at an annual average of 0.5 per cent according to the medium variant, al-though the range of variation for the annual growth rate over the period 2045-2050 could plausibly be between –0.05 per cent and 1.0 per cent, according to the low and high variants re-spectively. These projections imply that popula-tion growth is moving back to the levels typical of past centuries and that the rapid growth experi-enced during the second half of the twentieth cen-tury will most likely be an extraordinary event in the history of humanity.

Not only has the demographic transition been

responsible for such unprecedented growth, it has also caused major shifts in the age composition of the population. During the early stages of the demographic transition, when declines in morta l-ity are typically concentrated at younger ages and fertility remains high, the younger segments of the population increase in both absolute and rela-tive terms, with the result that the overall age dis-tribution of the population becomes younger. At later stages of the transition, when significant re-ductions in fertility occur and mortality continues to decline at older ages, the younger segments

156 United Nations Population Division World Population Prospects: The 2000 Revision, Volume III

become smaller in relative terms while the propor-tion of persons in older ages increases as more of them survive longer, thus producing an ageing of the population distribution.

During the past decades, the age distribution of

the world population has shifted only moderately towards the older ages. Until a decade or two ago a majority of countries in the less developed re-gions were still experiencing moderate to high fertility levels, and the effects of declining fertility on the age distribution of the population took some time to be felt (see chapter I). As a result, between 1950 and 2000, the proportions of chil-dren (persons aged 0 to 14 years) and of older per-sons (persons aged 60 years or over) changed only slightly, passing from 34 per cent to 30 per cent in the case of children and from 8 per cent to 10 per cent in the case of older persons. Consequently, the proportion of persons aged 15–59, the age range over which economic activity and child-bearing are concentrated, remained almost con-stant during that period, changing from 58 per cent to 60 per cent.

The projection results from the 2000 Revision indicate that in future decades the age distribution of the world population is almost certain to un-dergo profound changes. These will come about as more countries progress to later stages of the demographic transition and the long-term effects of fertility reductions make themselves felt. The effects of these changes will be especially marked with respect to the proportions of children and older persons (figure V.2). Thus, whereas in 2000 three out of every ten persons in the world were children, by 2050 there will be one child for every five persons. In contrast, whereas in 2000 one in every ten persons was aged 60 years or over, by 2050 one person out of every five will be in that age group. Furthermore, according to the medium variant, by the middle of the twenty-first century the number of older persons will slightly outnumber the number of children at the global level; and if fertility levels follow the path embod-ied by the low-fertility variant, by 2050 the num-ber of children could be only slightly under two thirds of the number of older persons. Even the high-fertility variant produces a marked reduction

Figure V.1. Average annual growth rate of the world population, 1750-2050

0.0

0.5

1.0

1.5

2.0

2.5

1750 1800 1850 1900 1950 2000 2050

Year

Gro

wth

rate

(pe

rcen

tage

)


Figure V.2. World population by broad age groups: estimates and medium variant projections: 1950, 2000 and 2050

1950 2000 2050 2.5 billion 6.1 billion 9.3 billion

in the number of children relative to older per-sons, with the former surpassing the latter by just 41 per cent.

Given the growing weight that the number of

older persons will have in the world popula tion overall and in the population of a growing number of countries, the 2000 Revision, just as the 1998 Revision, includes age-specific information for age groups 80-84, 85-89, 90-94, 95-99 and 100 or over. The availability of such information permits a better assessment of the dynamics of population ageing and of the expected growth patterns of the so-called “oldest old”. This chapter will review in some detail the results of the 2000 Revision with respect to the dynamics of population growth and its implications for population ageing from the perspective of the demographic transition.

A. THE GROWTH OF THE WORLD POPULATION According to the 2000 Revision, the population

of the world reached 6.1 billion persons in mid-2000, 50.4 per cent of whom were male and 49.6 per cent female. During 1995-2000 the world population increased, on average, by 79 million

persons annually, a figure considerably lower than the maximum annual increment of 86 million reached in 1985-1990 (see table V.2). Further-more, the annual increment of the world popula-tion is projected to decline steadily in the medium variant, reaching 43.5 million in 2045-2050. A declining trend in the average annual increments of the population also characterizes the low-fertility variant which projects that by 2045-2050 the world population will be declining by 3.7 mil-lion persons annually. In contrast, the high-fertility variant projects that the annual increments of the world population will continue to increase steadily, reaching a maximum of 103.2 million in 2040-2045 and then declining to 102.7 million by 2045-2050 (see table V.3). In all projection vari-ants the population growth rate experiences a steady decline starting in 2000. However, as stated earlier, the low-fertility variant leads to a population that by 2045-2050 is declining at a rate of 0.05 per cent per year, whereas the high-fertility variant produces a population that is still growing at a robust 0.96 per cent per year in 2045-2050 (figure V.3). The medium variant leads to a growth rate almost half-way between the other two: an annual average of 0.47 per cent

34%

58%

8%30%

60%

10%

0-14 15-59 60+

21%

58%

21%


TABLE V.2. ESTIMATED ANNUAL INCREMENTS OF THE POPULA TION OF THE WORLD AND ITS MAJOR AREAS, 1950-2000 (Millions)

Major area 1950- 1955

1955- 1960

1960- 1965

1965- 1970

1970- 1975

1975- 1980

1980- 1985

1985- 1990

1990- 1995

1995- 2000

World ............................................... 47.0 53.1 62.7 71.4 74.9 72.8 79.0 86.1 81.4 79.0

More developed regions................... 10.1 10.4 10.2 8.2 8.0 6.9 6.4 6.7 5.1 3.5 Less developed regions .................... 37.0 42.7 52.5 63.2 66.9 65.9 72.5 79.4 76.3 75.5

Least developed countries ............ 4.0 4.9 6.0 7.1 8.0 9.0 10.5 12.4 14.7 15.5 Less developed regions without the least developed countries .... 33.0 37.8 46.4 56.1 58.9 57.0 62.0 67.0 61.6 60.0

Europe.............................................. 5.6 5.8 5.9 4.4 3.9 3.4 2.7 3.1 1.3 -0.3 Northern America ............................ 3.1 3.5 3.1 2.5 2.3 2.3 2.7 2.8 3.1 3.2 Oceania............................................. 0.3 0.3 0.4 0.4 0.4 0.2 0.4 0.4 0.4 0.4 Africa ............................................... 5.1 6.1 7.3 8.6 9.9 12.2 14.4 16.1 16.8 18.0 Asia .................................................. 28.3 31.9 39.6 48.7 50.9 46.8 50.9 55.8 51.8 49.8 Latin America and the Caribbean .... 4.7 5.5 6.4 6.9 7.4 7.9 7.9 7.9 7.9 7.8 during 2045-2050. These different patterns of growth result in sizeable differences in the size of the population in 2050, with the low variant lead-ing to a total world population of 7.9 billion, the medium variant producing 9.3 billion, and the high variant resulting in 10.9 billion (figure V.4). Furthermore, by 2050 the population dynamics inherent in each variant differ considerably, with the population resulting from the medium variant moving slowly towards a stationary state (its net reproduction rate is close to 1 female child per woman); that produced by the high variant still having considerable potential for growth (its net reproduction rate is about 1.3 female children per woman in 2045-2050); and in the low variant, fal-ling considerably short from replacement (its net reproduction rate is projected to be 0.8 female children per woman in 2045-2050).

All the variants except the low variant result in substantial growth in the overall size of the world population dur ing the first half of the coming cen-tury. This growth is in large part a consequence of the sustained and high population growth recorded in the past decades, which created the conditions for its continuation. Indeed, even though fertility has continued to decline, the fast growth experi-enced in the past has given rise to large and in-creasing cohorts of potential mothers and fathers who can produce large numbers of offspring even as they have less children per couple than their

forebears. That is, increases in the number of peo-ple of reproductive age dampen the effects of de-clining fertility, at least over the medium term. As the results of the low-fertility variant demonstrate, low levels of fertility need to be sustained over relatively long periods before reductions in popu-lation occur.

As a result of the echo effect that past fertility

has on future population growth, relatively small differences in the path of fertility change can re-sult in considerable differences in population size. The three projection variants illustrate this point. Since they differ exclusively in the level of fertil-ity operating over the projection period, a differ-ence of about half a child in the total fertility ex-pected at the end of the projection period can result in a difference of about 17 per cent in popu-lation size by 2050, measured in terms of devia-tions of the high and the low variants from the medium variant.

In addition to the three variants mentioned

above, two other scenarios have been produced in the 2000 Revision. In one scenario, mortality is kept constant in each country at the level reached in 1995-2000 (constant-mortality scenario), while in another international migration is set to zero as of 2000 (zero-migration scenario). Unlike the low, medium and high variants, these two scenarios are not expected to reflect a likely course of either


TABLE V.3. PROJECTED AVERAGE ANNUAL INCREMENTS OF TH E POPULATION OF THE WORLD AND ITS MAJOR AREAS, 2000-2050, LOW, MEDIUM AND HIGH VARIANTS

(Millions)

Major area 2000- 2005

2005- 2010

2010- 2015

2015- 2020

2020- 2025

2025- 2030

2030- 2035

2035- 2040

2040- 2045

2045- 2050

Low

World ................................................... 68.0 61.2 56.2 51.6 45.7 36.2 25.4 15.3 6.0 -3.7

More developed regions....................... 1.4 0.4 -0.4 -0.9 -1.6 -2.6 -3.7 -4.7 -5.4 -5.9 Less developed regions ........................ 66.5 60.7 56.5 52.4 47.3 38.8 29.1 20.0 11.4 2.3

Least developed countries ................ 16.2 17.1 18.2 19.3 19.8 19.5 19.1 18.1 16.4 13.7 Less developed regions without the least developed countries ........ 50.4 43.6 38.3 33.1 27.6 19.3 10.0 1.9 -5.0 -11.5

Europe.................................................. -1.4 -2.0 -2.4 -2.7 -3.1 -3.6 -4.1 -4.6 -5.0 -5.3 Northern America ................................ 2.5 2.3 2.1 2.1 1.9 1.5 1.1 0.7 0.4 0.3 Oceania................................................. 0.4 0.4 0.3 0.3 0.3 0.2 0.2 0.1 0.1 0.1 Africa ................................................... 17.8 18.3 19.3 20.2 20.4 19.8 18.4 17.1 15.5 13.1 Asia ...................................................... 42.0 36.5 31.8 27.3 22.7 15.7 8.3 1.5 -4.6 -10.5 Latin America and Caribbean .............. 6.6 5.7 5.0 4.3 3.4 2.5 1.5 0.5 -0.5 -1.3

Medium

World ................................................... 76.9 76.9 76.3 74.4 71.5 66.7 61.2 55.8 50.0 43.5

More developed regions....................... 1.9 1.5 1.1 0.8 0.2 -0.5 -1.1 -1.7 -2.0 -2.2 Less developed regions ........................ 74.9 75.5 75.2 73.6 71.3 67.1 62.3 57.4 52.1 45.7

Least developed countries ................ 17.7 19.5 21.1 22.9 24.4 25.5 26.3 26.6 25.9 24.4 Less developed regions without the least developed countries ........ 57.2 56.0 54.1 50.7 46.9 41.7 36.0 30.9 26.1 21.3

Europe.................................................. -1.3 -1.5 -1.7 -1.9 -2.3 -2.6 -3.0 -3.3 -3.5 -3.6 Northern America ................................ 2.8 2.7 2.8 2.8 2.7 2.5 2.3 2.1 2.0 1.9 Oceania................................................. 0.4 0.4 0.4 0.4 0.4 0.3 0.3 0.3 0.2 0.2 Africa ................................................... 19.6 21.1 22.6 24.2 25.4 26.2 26.2 26.1 25.7 24.3 Asia ...................................................... 47.7 46.9 45.1 42.2 39.0 34.6 30.3 26.2 21.8 17.4 Latin America and Caribbean .............. 7.7 7.4 7.2 6.7 6.2 5.7 5.1 4.4 3.8 3.2

High

World ................................................... 85.4 90.9 95.3 97.2 98.0 99.2 100.9 102.5 103.2 102.7

More developed regions....................... 2.6 2.8 2.8 2.6 2.3 2.0 1.9 2.0 2.2 2.4 Less developed regions ........................ 82.8 88.2 92.5 94.6 95.7 97.3 99.0 100.5 101.0 100.3

Least developed countries ................ 18.8 21.4 23.9 26.4 28.9 31.4 33.8 35.8 36.9 37.1 Less developed regions without the least developed countries ....... 64.0 66.8 68.6 68.2 66.8 65.9 65.1 64.7 64.1 63.2

Europe.................................................. -1.1 -1.1 -1.1 -1.2 -1.5 -1.7 -1.8 -1.8 -1.7 -1.7 Northern America ................................ 3.2 3.4 3.7 3.8 3.8 3.8 3.8 3.9 4.0 4.2 Oceania................................................. 0.4 0.4 0.4 0.4 0.5 0.5 0.4 0.4 0.4 0.5 Africa ................................................... 20.9 23.2 25.7 28.0 30.3 32.5 34.2 35.9 37.1 37.5 Asia ...................................................... 53.3 55.7 57.3 57.0 55.9 55.0 55.0 54.9 54.2 53.2 Latin America and the Caribbean ........ 8.7 9.2 9.3 9.2 9.1 9.2 9.2 9.2 9.1 9.1


mortality or international migration. They are used only for illustrative purposes. If mortality in every country remained constant at its 1995-2000 level, the world population would rise to 8.1 bil-lion in 2050, about 1.2 billion less than in the me-dium variant. That is, the projected reductions of mortality in the medium variant account for about a third of the population increase expected be-tween 2000 and 2050.

B. POPULATION DYNAMICS IN THE MAJOR AREAS OF THE WORLD

During the twentieth century, the population

dynamics of the major world areas have differed markedly, especially after 1950. Thus, between 1950 and 2000, Africa’s population grew at 2.6 per cent per year, on average, while that of Latin America increased at 2.3 per cent and that of Asia at 1.9 per cent per year. Oceania’s population also experienced a robust pace of growth, at 1.8 per cent per year, while the population of Northern America grew at a more moderate rate of 1.2 per

cent per year. Only Europe experienced an aver-age growth rate below 1 per cent (0.6 per cent) during 1950-2000. These differences in the speed of population growth reflect the fact that the demographic transition proceeded at a different pace in each of the major areas. Yet, as table V.4 shows, with the sole exception of Africa, the aver-age annual rates of population growth declined between 1950-1975 and 1975-2000 in all major areas. The largest declines in relative terms were experienced by Northern America and Europe, where the rates of population growth dropped by slightly over a quarter and by nearly two-thirds, respectively.

When countries are grouped in terms of level of

development, the highest rates of population growth were experienced by the least developed countries, where the population grew at 2.4 per cent annually during 1950-2000. The rest of the countries in the less developed regions experi-enced a slightly lower average rate of population growth (2.05 per cent per year), which does not

Figure V.3. Estimated and projected average annual growth rate of the world population: low, medium and high variants, 1950-2050

-0.5

0

0.5

1

1.5

2

2.5

1950-1

955

1955-1

960

1960-1

965

1965-1

970

1970-1

975

1975-1

980

1980-1

985

1985-1

990

1990-1

995

1995-2

000

2000-2

005

2005-2

010

2010-2

015

2015-2

020

2020-2

025

2025-2

030

2030-2

035

2035-2

040

2040-2

045

2045-2

050

Period

Gro

wth

rate

(pe

rcen

tage

)

High Low Medium


TABLE V.4. ESTIMATED AND PROJECTED AVERAGE ANNUAL POPULATION GROWTH RATE S BY MAJOR AREA, DEVELOPMENT GROUP AND PROJECTION VARIANT, 1950-2050

2000-2050 Major area 1950-2000 1950-1975 1975-2000 Low Medium High

World ....................................................... 1.75 1.91 1.59 0.52 0.86 1.18

More developed regions........................... 0.76 1.01 0.51 -0.21 -0.02 0.19 Less developed regions ............................ 2.10 2.28 1.91 0.67 1.03 1.36

Least developed countries .................... 2.41 2.26 2.55 1.71 2.04 2.35 Less developed regions without the least developed countries ............ 2.05 2.28 1.82 0.44 0.81 1.15

Europe...................................................... 0.57 0.84 0.29 -0.54 -0.37 -0.21 Northern America .................................... 1.21 1.40 1.02 0.43 0.66 0.94 Oceania..................................................... 1.77 2.09 1.44 0.66 0.87 1.09 Africa ....................................................... 2.56 2.44 2.68 1.52 1.85 2.15 Asia .......................................................... 1.93 2.15 1.71 0.42 0.78 1.12 Latin America and the Caribbean ............ 2.27 2.62 1.91 0.47 0.88 1.26

Figure V.4. Estimated and projected world population: low, medium and high variants, 1950-2050

0.00

2.00

4.00

6.00

8.00

10.00

12.00

1950 1960 1970 1980 1990 2000 2010 2020 2030 2040 2050

Year

Popu

latio

n(in

bill

ions

)

High Low Medium


change by much when the least developed coun-tries are also included in the group (it increases to 2.1 per cent per year). The most important differ-ence, therefore, was that between the growth rates of the less developed regions as a whole and those of the more developed regions, since the latter grew at a low average rate of 0.8 per cent annually during 1950-2000. Marked differences between the rate of population growth of the two major groups of countries by level of development are expected to continue well into the twenty-first century. Thus, over the 2000-2050 period, the av-erage annual population growth rate of the more developed regions is expected to be within a range of –0.2 per cent to 0.2 per cent in the low and high variants, whereas that for less developed regions it is expected to be between 0.7 per cent and 1.4 per cent (see table V.4). According to the different projection variants, the growth rate of the less de-veloped regions is expected to exceed that of the more developed regions by amounts ranging any-where from 0.9 or 1.2 percentage points. With respect to the medium variant, such a differ-ence implies that, whereas the population of the more developed regions is expected to decline slightly between 2000 and 2050, at an average rate of –0.02 per cent annually, that of the less developed regions is expected to increase at a moderate pace of 1.03 per cent annually.

Differences are also expected to remain marked

at the level of major areas (see table V.4). Thus, during 2000-2050, average annual growth at the regional level is expected to range from –0.4 per cent in Europe to 1.9 per cent in Africa according to the medium variant; and according to all pro-jection variants, Africa is expected to be the fast-est growing region, maintaining an average annual growth rate of slightly over 2.1 per cent in the high variant and experiencing a still robust aver-age annual rate of growth of 1.5 per cent in the low variant. Europe provides a striking contrast by experiencing an average annual negative growth in all variants, -0.2 per cent according to the high variant and -0.5 per cent according to the low variant over the first half of the coming century. In between these extremes, a considerable degree of convergence is observed in the projected growth rates for Asia, Latin America and the Car-ibbean, and Oceania. Their respective average annual growth rates differ from one another by at

most 0.3 percentage points in each of the three variants, ranging from 1.1 per cent to 1.3 per cent according to the high variant and from 0.4 to 0.7 per cent according to the low variant. In all variants, Latin America and the Caribbean is ex-pected to experience the highest average annual growth rate among major areas with moderately increasing populations, whereas the whole of Asia is expected to experience average annual popula-tion growth rates nearer to the lower limit of each range. The low fertility projected for China in all variants has considerable influence on these re-sults.

The differences in trends among the major areas

discussed above in terms of average annual growth rates for lengthy periods remain when ex-amined in terms of averages over quinquennial periods. For the past, consideration of five-year periods makes plain the different paths followed by the different major areas to achieve low popu-lation growth. The growth rate of the population of Europe, for instance, declined steadily during 1955-1985 and so did that for Northern America between 1955-1980. In the less developed major areas, the first significant decline in the growth rate (of at least 10 per cent from the preceding quinquennium) occurred in 1975-1980 in Asia and Oceania, and in 1980-1985 for Latin America and the Caribbean. By 2000 Africa was the only major area where a marked decline of the growth rate had not yet occurred although an incipient reduc-tion of the growth rate had taken place since 1990 (see table V.5). For the projection period all vari-ants produce steadily declining growth rates for Africa, Asia, and Latin America and the Carib-bean (see tables V.6, V.7 and V.8). Declines are generally projected as well for Europe, Northern America and Oceania except in the high variant, where the growth rate for Europe tends to stagnate after 2025 and that for Oceania shows a slight in-crease after 2045. By 2045-2050, the population of all major areas except Europe will be increas-ing at moderate rates of growth according to the high variant: the population of Africa is projected to grow at 1.68 per cent per year, and that of Europe will have a negative growth rate of -0.26 per cent per year. In the medium variant most ma-jor areas will be experiencing low rates of growth by 2045-2050, with Africa having the highest growth rate at 1.26 per cent per year and Europe


TABLE V.5. ESTIMATED GROWTH RATE OF THE POPULATION O F THE WORLD, ITS MAJOR AREAS AND REGIONS, 1950-2000 (Percentage)

Major area or region 1950- 1955

1955- 1960

1960- 1965

1965- 1970

1970- 1975

1975- 1980

1980- 1985

1985- 1990

1990- 1995

1995- 2000

World ................................................... 1.79 1.84 1.98 2.04 1.93 1.72 1.71 1.71 1.49 1.35 More developed regions....................... 1.20 1.17 1.09 0.83 0.78 0.65 0.59 0.59 0.44 0.30 Less developed regions ........................ 2.06 2.14 2.35 2.51 2.35 2.07 2.06 2.03 1.78 1.62 Least developed countries ................. 1.93 2.15 2.35 2.46 2.44 2.43 2.51 2.61 2.71 2.50 Less developed regions without the least developed countries ........ 2.07 2.14 2.35 2.51 2.34 2.03 2.00 1.95 1.64 1.48 Europe.................................................. 0.99 0.99 0.96 0.68 0.59 0.49 0.38 0.43 0.18 -0.04

Eastern Europe................................. 1.48 1.33 1.04 0.70 0.66 0.64 0.56 0.48 -0.05 -0.38 Northern Europe............................... 0.39 0.53 0.76 0.56 0.38 0.20 0.22 0.35 0.32 0.23 Southern Europe............................... 0.83 0.77 0.82 0.68 0.81 0.80 0.38 0.29 0.14 0.18 Western Europe................................ 0.66 0.84 1.04 0.70 0.42 0.15 0.16 0.49 0.55 0.23

Northern America ................................ 1.70 1.77 1.46 1.10 0.97 0.93 1.03 1.02 1.08 1.04 Oceania................................................. 2.18 2.17 2.12 1.92 2.08 1.12 1.55 1.57 1.59 1.37

Australia/New Zealand .................... 2.26 2.19 2.06 1.82 2.02 0.81 1.32 1.39 1.36 1.11 Melanesia ......................................... 1.74 2.02 2.27 2.27 2.46 2.45 2.44 2.15 2.44 2.26 Micronesia........................................ 2.20 2.32 2.69 2.90 2.10 1.82 2.46 3.43 2.29 2.16 Polynesia.......................................... 2.89 2.63 2.79 2.47 1.61 1.47 1.44 1.39 1.08 1.11

Africa ................................................... 2.17 2.33 2.47 2.59 2.61 2.79 2.87 2.78 2.54 2.41

Eastern Africa .................................. 2.24 2.43 2.64 2.75 2.80 2.86 2.94 3.04 2.52 2.67 Middle Africa................................... 1.81 2.00 2.23 2.47 2.39 2.80 2.99 3.05 3.42 2.61 Northern Africa................................ 2.27 2.38 2.42 2.49 2.43 2.65 2.78 2.34 2.06 1.86 Southern Africa ................................ 2.29 2.42 2.59 2.64 2.60 2.41 2.43 2.20 1.98 1.61 Western Africa ................................. 2.15 2.29 2.42 2.52 2.65 2.94 2.95 2.91 2.73 2.67

Asia ...................................................... 1.93 1.97 2.21 2.42 2.25 1.86 1.85 1.85 1.58 1.41

Eastern Asia ..................................... 1.75 1.52 1.97 2.42 2.11 1.43 1.32 1.41 1.01 0.84 South-central Asia............................ 2.04 2.31 2.35 2.35 2.32 2.19 2.24 2.18 1.99 1.81 South-eastern Asia ........................... 2.08 2.40 2.47 2.51 2.34 2.16 2.15 2.00 1.83 1.58 Western Asia.................................... 2.64 2.76 2.73 2.65 2.77 2.72 2.84 2.66 2.38 2.28

Latin America and the Caribbean ........ 2.65 2.70 2.75 2.58 2.45 2.32 2.08 1.88 1.72 1.56

Caribbean ......................................... 1.77 1.87 2.07 1.84 1.78 1.48 1.56 1.40 1.18 1.07 Central America............................... 2.75 3.05 3.10 3.15 3.03 2.68 2.25 2.06 2.02 1.85 South America.................................. 2.75 2.70 2.72 2.47 2.32 2.29 2.07 1.87 1.66 1.51

the lowest at -0.59 per cent per year. In contrast, the low variant produces declining populations in three major areas: Europe, Asia and Latin Amer-ica and the Caribbean. Thus, according to the low variant, by 2045-2050 Africa would be grow-ing at 0.79 per cent per year; Asia and Latin America and the Caribbean would have negative growth of –0.23 per year and –0.20 per cent per

year, respectively. Northern America and Oce-ania will have positive growth rates in the range of 0.08 per cent and 0.15 per cent per year; and the population of Europe will be decreasing at a rate of –0.93 per cent per year.

As a result of the different growth rates experi-

enced in the past by the major areas of the world


TABLE V.6. PROJECTED GROWTH RATE OF THE POPULATION OF THE WORLD, ITS MAJOR AREAS AND REGIONS ACCORDING TO THE LOW VARIANT, 2000-2050

(Percentage)


2005- 2010

2010- 2015

2015- 2020

2020- 2025

2025- 2030

2030- 2035

2035- 2040

2040- 2045

2045- 2050

World ................................................. 1.09 0.93 0.82 0.73 0.62 0.48 0.33 0.20 0.08 -0.05 More developed regions..................... 0.12 0.04 -0.03 -0.07 -0.13 -0.22 -0.32 -0.41 -0.49 -0.54 Less developed regions ...................... 1.32 1.14 1.00 0.89 0.77 0.61 0.44 0.30 0.17 0.03

Least developed countries .............. 2.32 2.20 2.10 2.01 1.86 1.68 1.52 1.34 1.14 0.91 Less developed regions without the least developed countries ...... 1.16 0.95 0.80 0.67 0.54 0.37 0.19 0.04 -0.09 -0.22

Europe................................................ -0.20 -0.28 -0.34 -0.39 -0.45 -0.54 -0.64 -0.74 -0.84 -0.93

Eastern Europe............................... -0.57 -0.58 -0.60 -0.62 -0.70 -0.80 -0.89 -0.97 -1.05 -1.15 Northern Europe............................. 0.11 0.00 -0.04 -0.05 -0.09 -0.18 -0.31 -0.44 -0.54 -0.59 Southern Europe............................. -0.02 -0.21 -0.34 -0.44 -0.53 -0.61 -0.71 -0.84 -0.98 -1.12 Western Europe.............................. 0.11 -0.02 -0.11 -0.16 -0.22 -0.31 -0.41 -0.53 -0.63 -0.70

Northern America .............................. 0.79 0.69 0.61 0.59 0.53 0.42 0.29 0.19 0.11 0.08 Oceania............................................... 1.17 1.06 0.97 0.86 0.75 0.63 0.48 0.34 0.21 0.15

Australia/New Zealand .................. 0.91 0.79 0.68 0.58 0.49 0.39 0.27 0.17 0.09 0.04 Melanesia ....................................... 1.99 1.88 1.77 1.63 1.45 1.25 1.01 0.74 0.48 0.41 Micronesia...................................... 2.21 1.97 1.75 1.51 1.23 1.00 0.81 0.61 0.41 0.20 Polynesia........................................ 1.01 1.03 1.02 0.89 0.73 0.54 0.32 0.15 0.01 -0.14

Africa ................................................. 2.13 1.98 1.89 1.81 1.67 1.49 1.30 1.13 0.98 0.79

Eastern Africa ................................ 2.19 2.12 2.09 2.02 1.87 1.71 1.55 1.38 1.18 0.96 Middle Africa................................. 2.86 2.78 2.76 2.67 2.52 2.32 2.07 1.80 1.50 1.15 Northern Africa.............................. 1.58 1.25 1.03 0.92 0.80 0.61 0.42 0.26 0.12 -0.01 Southern Africa .............................. 0.58 -0.12 -0.41 -0.52 -0.40 -0.32 -0.27 -0.20 -0.11 -0.04 Western Africa ............................... 2.51 2.39 2.26 2.08 1.85 1.57 1.28 1.10 0.99 0.85

Asia .................................................... 1.11 0.92 0.77 0.64 0.51 0.35 0.18 0.03 -0.10 -0.23

Eastern Asia ................................... 0.54 0.39 0.31 0.20 0.04 -0.15 -0.31 -0.45 -0.61 -0.77 South-central Asia.......................... 1.56 1.33 1.06 0.88 0.77 0.60 0.42 0.25 0.12 -0.01 South-eastern Asia ......................... 1.16 0.86 0.75 0.66 0.55 0.39 0.20 0.05 -0.10 -0.23 Western Asia.................................. 1.91 1.75 1.66 1.55 1.40 1.22 1.06 0.93 0.79 0.65

Latin America and the Caribbean ...... 1.24 1.00 0.85 0.69 0.54 0.39 0.22 0.07 -0.07 -0.20

Caribbean ....................................... 0.88 0.73 0.59 0.43 0.28 0.12 -0.03 -0.17 -0.34 -0.46 Central America............................. 1.47 1.18 0.97 0.80 0.63 0.47 0.29 0.13 -0.03 -0.18 South America................................ 1.18 0.96 0.83 0.68 0.53 0.38 0.22 0.07 -0.06 -0.18

and of the expected continuation of those differ-ences in the future, these areas will experience fairly different trends in terms of changes in popu-lation size. For example, the population of Africa increased 3.6 times between 1950 and 2000 and is expected to keep on rising over the first half of the

twenty-first century so that by 2050 it is likely to have doubled or nearly tripled again in size (see table V.9). The population of Africa is therefore expected to grow from 794 million persons in 2000 to between 1.7 billion and 2.3 billion per-sons by 2050, with the medium variant yielding


TABLE V.7. PROJECTED GROWTH RATE OF THE POPULATION O F THE WORLD, ITS MAJOR AREAS AND REGIONS ACCORDING TO THE MEDIUM VARIANT, 2000-2050

(Percentage)


2005- 2010

2010- 2015

2015- 2020

2020- 2025

2025- 2030

2030- 2035

2035- 2040

2040- 2045

2045- 2050

World ................................................ 1.23 1.16 1.09 1.01 0.92 0.82 0.73 0.64 0.56 0.47 More developed regions.................... 0.16 0.12 0.09 0.06 0.02 -0.04 -0.09 -0.14 -0.17 -0.19 Less developed regions ..................... 1.48 1.39 1.30 1.19 1.09 0.98 0.86 0.77 0.67 0.57

Least developed countries ............. 2.52 2.46 2.36 2.28 2.17 2.04 1.91 1.76 1.58 1.38 Less developed regions without the least developed countries ..... 1.32 1.21 1.10 0.98 0.87 0.74 0.62 0.52 0.43 0.34

Europe............................................... -0.18 -0.21 -0.25 -0.28 -0.33 -0.39 -0.45 -0.51 -0.55 -0.59

Eastern Europe.............................. -0.55 -0.51 -0.50 -0.51 -0.58 -0.65 -0.69 -0.71 -0.74 -0.79 Northern Europe............................ 0.13 0.07 0.06 0.08 0.05 -0.03 -0.13 -0.22 -0.25 -0.25 Southern Europe............................ 0.00 -0.15 -0.26 -0.35 -0.42 -0.47 -0.54 -0.62 -0.71 -0.80 Western Europe............................. 0.13 0.05 -0.01 -0.05 -0.09 -0.15 -0.23 -0.30 -0.35 -0.38

Northern America ............................. 0.88 0.82 0.80 0.78 0.73 0.65 0.57 0.50 0.46 0.45 Oceania.............................................. 1.24 1.16 1.09 1.01 0.94 0.84 0.74 0.63 0.55 0.52

Australia/New Zealand ............. 0.95 0.85 0.77 0.69 0.63 0.55 0.46 0.40 0.36 0.36 Melanesia .................................. 2.17 2.07 1.98 1.86 1.72 1.56 1.37 1.15 0.94 0.89 Micronesia................................. 2.29 2.12 1.94 1.74 1.50 1.33 1.19 1.04 0.89 0.73 Polynesia................................... 1.18 1.24 1.26 1.16 1.05 0.91 0.75 0.63 0.54 0.43

Africa ................................................ 2.33 2.23 2.15 2.07 1.97 1.84 1.69 1.55 1.42 1.26

Eastern Africa ............................... 2.42 2.38 2.34 2.27 2.16 2.05 1.92 1.77 1.60 1.41 Middle Africa................................ 3.00 3.03 2.99 2.90 2.78 2.64 2.43 2.19 1.91 1.60 Northern Africa............................. 1.81 1.59 1.39 1.28 1.16 1.01 0.88 0.77 0.67 0.57 Southern Africa ............................. 0.80 0.15 -0.07 -0.09 0.08 0.20 0.29 0.37 0.48 0.58 Western Africa .............................. 2.66 2.58 2.46 2.30 2.12 1.90 1.67 1.52 1.43 1.31

Asia ................................................... 1.26 1.16 1.06 0.94 0.83 0.71 0.60 0.51 0.41 0.32

Eastern Asia .................................. 0.66 0.61 0.57 0.44 0.29 0.15 0.05 -0.03 -0.15 -0.27 South-central Asia......................... 1.68 1.55 1.37 1.22 1.13 1.00 0.87 0.75 0.66 0.57 South-eastern Asia ........................ 1.38 1.21 1.11 1.02 0.92 0.80 0.68 0.57 0.47 0.38 Western Asia................................. 2.13 2.01 1.92 1.82 1.69 1.56 1.44 1.34 1.22 1.11

Latin America and the Caribbean ..... 1.42 1.29 1.17 1.04 0.92 0.80 0.69 0.58 0.49 0.40

Caribbean ...................................... 0.99 0.92 0.83 0.72 0.60 0.47 0.37 0.28 0.17 0.10 Central America............................ 1.64 1.46 1.30 1.15 1.01 0.88 0.75 0.64 0.53 0.42 South America............................... 1.38 1.27 1.15 1.03 0.91 0.80 0.69 0.59 0.50 0.43

nearly 2 billion persons. These projections imply that by 2050 it is very likely that the population of Africa as a whole will exceed that of China in 2000. It is noteworthy that even according to the low variant, Africa’s population is expected to double over the next half century. As table V.9

indicates, according to both the medium and high variants the largest share of the expected increase in population size will occur between 2025-2050. Only in the low variant does most of the expected increase in the population of Africa occur before 2025.


TABLE V.8. PROJECTED GROWTH RATE FOR THE POPULATION OF THE WORLD, ITS MAJOR AREAS AND REGIONS ACCORDING TO THE HIGH VARIANT, 2000-2050

(Percentage)


2005- 2010

2010- 2015

2015- 2020

2020- 2025

2025- 2030

2030- 2035

2035- 2040

2040- 2045

2045- 2050

World ................................................. 1.36 1.36 1.33 1.27 1.20 1.15 1.10 1.06 1.02 0.96 More developed regions..................... 0.22 0.23 0.23 0.21 0.18 0.16 0.15 0.16 0.17 0.19 Less developed regions ...................... 1.63 1.60 1.56 1.47 1.39 1.32 1.26 1.20 1.14 1.07

Least developed countries .............. 2.67 2.66 2.61 2.53 2.45 2.36 2.26 2.15 1.99 1.82 Less developed regions without the least developed countries ...... 1.47 1.42 1.36 1.27 1.17 1.09 1.02 0.97 0.91 0.86

Europe................................................ -0.15 -0.15 -0.15 -0.17 -0.21 -0.25 -0.26 -0.26 -0.25 -0.26 Eastern Europe............................... -0.53 -0.44 -0.40 -0.41 -0.47 -0.50 -0.49 -0.45 -0.42 -0.44 Northern Europe............................. 0.16 0.14 0.17 0.20 0.18 0.12 0.05 0.02 0.05 0.09 Southern Europe............................. 0.02 -0.09 -0.18 -0.26 -0.30 -0.33 -0.36 -0.40 -0.43 -0.48 Western Europe.............................. 0.15 0.11 0.09 0.07 0.04 -0.01 -0.05 -0.07 -0.06 -0.05

Northern America .............................. 1.01 1.02 1.03 1.01 0.97 0.92 0.88 0.86 0.85 0.85

Oceania............................................... 1.32 1.27 1.23 1.18 1.12 1.07 1.00 0.94 0.89 0.90 Australia/New Zealand .................. 0.99 0.93 0.88 0.83 0.78 0.72 0.67 0.65 0.65 0.68 Melanesia ....................................... 2.35 2.26 2.17 2.08 1.98 1.87 1.72 1.54 1.36 1.34 Micronesia...................................... 2.32 2.23 2.13 1.96 1.76 1.63 1.55 1.45 1.34 1.23 Polynesia........................................ 1.34 1.43 1.49 1.42 1.35 1.26 1.17 1.08 1.03 0.97

Africa ................................................. 2.48 2.43 2.39 2.31 2.23 2.15 2.04 1.93 1.82 1.68 Eastern Africa ................................ 2.57 2.57 2.57 2.50 2.42 2.34 2.24 2.12 1.97 1.81 Middle Africa................................. 3.03 3.17 3.23 3.13 3.02 2.91 2.74 2.55 2.30 2.01 Northern Africa.............................. 2.02 1.89 1.72 1.59 1.48 1.38 1.31 1.24 1.17 1.09 Southern Africa .............................. 0.99 0.40 0.24 0.30 0.51 0.68 0.80 0.90 1.02 1.14 Western Africa ............................... 2.80 2.74 2.66 2.51 2.37 2.21 2.03 1.91 1.83 1.73

Asia .................................................... 1.40 1.37 1.31 1.23 1.13 1.06 1.00 0.95 0.90 0.84 Eastern Asia ................................... 0.79 0.75 0.75 0.68 0.53 0.43 0.38 0.35 0.28 0.20 South-central Asia.......................... 1.81 1.76 1.66 1.54 1.46 1.38 1.30 1.23 1.17 1.12 South-eastern Asia ......................... 1.59 1.54 1.44 1.34 1.26 1.19 1.13 1.07 1.00 0.94 Western Asia.................................. 2.33 2.24 2.16 2.06 1.96 1.87 1.80 1.73 1.63 1.54

Latin America and the Caribbean ...... 1.60 1.58 1.47 1.35 1.26 1.19 1.13 1.07 1.01 0.96 Caribbean ....................................... 1.11 1.11 1.07 0.98 0.89 0.82 0.77 0.73 0.66 0.63 Central America............................. 1.82 1.73 1.61 1.47 1.35 1.27 1.19 1.12 1.05 0.97 South America................................ 1.57 1.57 1.46 1.34 1.26 1.20 1.14 1.08 1.02 0.98

No other major area is expected to experience a proportionate increase in population size similar to that expected for Africa. The population of Latin America and the Caribbean might nearly double if the high variant were to become reality, and that of Asia would increase by some 75 per cent. In terms of numbers, the population of Asia is expected to rise from the 3.7 billion persons in 2000 to somewhere in the range of 4.5 billion to

6.4 billion (table V.9). For Latin America and the Caribbean the increase would be from 519 million in 2000 to somewhere between 657 million and 975 million in 2050. Increases in population size might also be moderate in Oceania and Northern America, where the current populations of 31 mil-lion and 314 million respectively might rise to ranges of 42 million to 53 million in the case of Oceania and 389 million to 502 million in the case


TABLE V.9. ESTIMATED AND PROJECTED POPULATION BY MAJOR AREA, DEVELOPMENT GROUP AND PROJECTION VARIANT, 1950-2050

(Millions) 2025 2050

Major area 1950 1975 2000 Low Medium High

Low Medium High

World ................................................... 2 519 4 066 6 057 7 470 7 937 8 391 7 866 9 322 10 934

More developed regions....................... 814 1 048 1 191 1 187 1 219 1 257 1 075 1 181 1 309Less developed regions ........................ 1 706 3 017 4 865 6 283 6 718 7 135 6 791 8 141 9 625

Least developed countries ................ 197 348 658 1 112 1 186 1 255 1 545 1 830 2 130Less developed regions without the least developed countries ........ 1 508 2 670 4 207 5 172 5 532 5 879 5 246 6 312 7 495

Europe.................................................. 548 676 727 669 684 698 556 603 654Northern America ................................ 172 243 314 369 384 404 389 438 502Oceania................................................. 13 21 31 39 40 41 42 47 53Africa ................................................... 221 406 794 1 275 1 358 1 434 1 694 2 000 2 320Asia ...................................................... 1 399 2 397 3 672 4 474 4 777 5 068 4 527 5 428 6 430Latin America and the Caribbean ........ 167 322 519 644 695 746 657 806 975 of Northern America. For all of these major areas, therefore, the population expected in 2050 accord-ing to all projection variants would be la rger than that estimated for 2000. Only in the case of Europe do all variants result in a smaller popula-tion in 2050 than in 2000.

The contrasting patterns of past as well as pro-jected future growth for the major areas have in-teresting implications for the distribution of popu-lation increases among them. During 1950-2000, 89 per cent of all population growth at the world level occurred in the less developed regions and 11 per cent in the more developed regions but by 2045-2050 all population growth is expected to be concentrated among the less developed regions, since the more developed regions, which include Australia/New Zealand, Europe, Japan and North-ern America, will experience a net reduction of their overall population in the low and medium variants (table V.3). In fact, according to the low and medium variants the positive growth expected for Australia/New Zealand and Northern America will not be able to counterbalance the reductions experienced in Europe. At the level of major ar-eas, the increase in population size between 2000 and 2025 is expected to be concentrated mostly in Africa and Asia, with the latter accounting for between 57 per cent and 60 per cent of all growth and Africa accounting for between 27 per cent to

34 per cent according to the different projection variants (table V.9). However, between 2025 and 2050, the contributions made by these major areas to overall increases in population size vary con-siderably according to the different projection variants. Asia, for instance, would contribute be-tween 47 per cent and 54 per cent of all popula-tion growth during 2025-2050 according to the medium and high variants respectively. Yet, ac-cording to the low variant, Asia would experience only 13 per cent of the world population growth. Under the low variant, therefore, Africa would become the source of virtually all population growth in the world, contributing an increase of 419 million persons during 2025-2050; in con-trast, Europe would be responsible for a reduction of the population by 113 million persons (table V.9). According to the medium and high variants, reductions of that magnitude would not yet have materialized by 2050, so that the contribution of Africa to global population increases, while very signif icant, would represent approximately 35 per cent to 46 per cent of the global increase in popu-lation during 2025-2050.

Another consequence of the different patterns of

growth will be a redistribution of the population among the major areas. Table V.10 shows the per-centage distribution of population among major areas and development groups at various points in


TABLE V.10. DISTRIBUTION OF THE P OPULATION BY MAJOR A REA AND DEVELOPMENT GROUP, LOW, MEDIUM AND HIGH VARIANTS, SELECTED YEARS, 1950-2050

(Percentage) 2025 2050

Major area 1950 1975 2000 Low Medium High Low Medium High

More developed regions......................... 32.3 25.8 19.7 15.9 15.4 15.0 13.7 12.7 12.0 Less developed regions .......................... 67.7 74.2 80.3 84.1 84.6 85.0 86.3 87.3 88.0

Least developed countries .................. 7.8 8.6 10.9 14.9 14.9 15.0 19.6 19.6 19.5 Less developed regions without the least developed countries .......... 59.9 65.7 69.5 69.2 69.7 70.1 66.7 67.7 68.5

Europe.................................................... 21.8 16.6 12.0 9.0 8.6 8.3 7.1 6.5 6.0 Northern America .................................. 6.8 6.0 5.2 4.9 4.8 4.8 5.0 4.7 4.6 Oceania................................................... 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Africa ..................................................... 8.8 10.0 13.1 17.1 17.1 17.1 21.5 21.5 21.2 Asia ........................................................ 55.5 58.9 60.6 59.9 60.2 60.4 57.5 58.2 58.8 Latin America and the Caribbean .......... 6.6 7.9 8.6 8.6 8.8 8.9 8.4 8.6 8.9 time. Since 1950, Asia has accounted for more than half of the world population and its share, which was about 61 per cent in 2000, is not ex-pected to change markedly over the next half cen-tury. Consequently, according to all projection variants, it will drop only slightly to about 58 per cent or 59 per cent by 2050. The shares of Latin America and the Caribbean and Oceania are also expected to remain substantially the same during 2000-2050. Probably the most important changes expected during that period concern the popula-tion shares of Africa and the more developed re-gions. Significantly, Africa’s share is expected to rise from 13 per cent to 22 per cent in the medium variant, while the share of the more developed regions will experience a nearly equivalent reduc-tion, from 20 per cent to 13 per cent. Over the course of the next half-century, Africa and the more developed regions will therefore trade places in terms of their share of the world population.

In terms of total population, the more developed

regions had 1.2 billion inhabitants in 2000, whereas the less developed regions had about four times as many, 4.9 billion (table V.9). By 2050, the medium variant indicates that the population of the more developed regions will remain nearly unchanged at about 1.2 billion, whereas that of the less developed regions will have risen to 8.1 bil-lion, an increase of 67 per cent. At the end of the demographic transition, the more developed re-

gions are already experiencing low rates of popu-lation growth and very low fertility. Conse-quently, the changes that they are expected to undergo according to any of the three assumptions made about the future course of fertility represent a less radical departure from current conditions than they do for some of the less developed re-gions where fertility is still high and the reduc-tions implied by the assumptions made are very substantial. As a result, the range over which the size of the population of more developed regions is expected to vary in 2050 is narrower in absolute terms than that for the less developed regions, ranging from 1.1 billion to 1.3 billion according to the low and high variants respectively. This range can be compared with the equivalent for the less developed regions: from 6.8 billion in the low variant to 9.6 billion in the high variant. Owing to their high share of the world population as well as their large potential for sustained population growth, the less developed regions have a major influence on the size and composition of the world population as a whole.

C. POPULATION GROWTH AT THE

REGIONAL LEVEL The differences in population growth and size

discussed above in terms of major areas persist and show some diversification at the level of re-gions. Thus, in general, all the regions of Africa


display considerably higher rates of population growth than those of Asia or Latin America and the Caribbean although, as table V.5 shows, cer-tain regions in other developing areas have exhib-ited relatively high rates of population growth over the period 1950-2000. Within Africa during 1950-1955, Eastern Africa, Northern Africa and Southern Africa were growing at rates of about 2.2 per cent to 2.3 per cent. Middle Africa and Western Africa displayed slightly lower rates of growth (1.8 per cent and 2.2 per cent respectively) because they were subject to higher mortality lev-els than other regions in the continent. By 1990-1995, the decline of mortality experienced by Middle Africa had made it the fastest-growing region of the world with an annual growth rate of 3.4 per cent per year. Similarly, the rates of growth of both Eastern Africa and Western Africa were high at 2.5 per cent and 2.7 per cent respec-tively. Northern Africa and Southern Africa, where fertility had shown an earlier decline than in the rest of the continent, had more moderate rates of growth at around 2 per cent per year. Over the course of the projection period, growth rates for all regions of Africa are expected to decline (see tables V.6 to V.8). The reductions are most substantial for Southern Africa, where high levels of mortality are expected to occur as a result of the HIV/AIDS epidemic, and for Northern Africa, where a rapid reduction in fertility is taking place. According to the medium variant the growth rate of these regions falls to 0.6 per cent by 2045-2050; according to the low variant the population of both Northern Africa and Southern Africa will be declining by that time (the only two regions in Africa where this is expected to occur in the low variant); and, according to the high variant, their rate of growth would be of the order of 1.1 per cent per year by 2045-2050. In contrast, the growth rates of Eastern Africa, Middle Africa and Western Africa are projected to be between 1.3 per cent and 1.6 per cent in the medium variant and approximately half a percentage below that level and half a percentage above it in the low and high variants respectively. In all variants, Middle Africa will continue to be the region with the fast-est growing population in the world during the entire projection period.

In 1995-2000, three other regions were showing

growth rates of at least 2 per cent per year: Mela-

nesia, Micronesia and Western Asia. With the possible exception of Micronesia, all these regions were further along in the transition to low fertility than the fastest-growing regions of Africa. Fur-thermore, in all of them mortality is expected to decline steadily over the course of the projection period. Consequently, by 2045-2050 they tend to exhibit growth rates that are lower than those of the fast-growing regions of Africa but still higher than those of Southern Africa or Northern Africa. In terms of the medium variant, the growth rates of Melanesia, Micronesia and Western Asia de-cline to a range of 0.7 per cent to 1.1 per cent per year by 2045-2050.

Regions with a growth rate at the intermediate

level (between 1 per cent and 2 per cent) in 1995-2000, included South-central Asia and South-eastern Asia; Northern America; the Caribbean, Central America and South America; Austra-lia/New Zealand and Polynesia. The lowest growth rates in the group correspond to Northern America and the Caribbean, with a growth rate of about 1 per cent per year. According to both the low and medium variants, the growth rates in both regions are expected to decline to very low levels by 2045-2050. In the low variant, the Caribbean’s growth rate in 2045-2050 is negative at –0.5 per cent per year, and that of Northern America is nearly zero. In the medium variant, the growth rate of Northern America will reach 0.5 per cent per year largely because of the effect of continued immigration; that of the Caribbean will hover around 0.1 per cent per year. The growth rates of Australia/New Zealand, Polynesia, South Amer-ica, Central America, South-central Asia and South-eastern Asia all converge towards the range of 0.3 per cent to 0.6 per cent per year by 2045-2050 according to the medium variant.

The remaining regions are Eastern Asia and the

very slow-growing regions of Europe. In 1995-2000, Eastern Asia was the only region of the de-veloping world with a growth rate below 1 per cent per year. The sharp fertility decline experi-enced by China is largely responsible for produc-ing that relative low value for the growth rate. Over the projection period Eastern Asia is ex-pected to continue experiencing low growth. Ac-cording to the medium variant, Eastern Asia will likely be the only region of the developing world


experiencing a reduction of population in 2045-2050. In the low variant, Eastern Asia’s popula-tion is expected to be declining even faster in 2045-2050 (at a rate of –0.8 per cent per year). Only in the high variant is the population of the region expected to keep on growing until 2050.

Among the regions of Europe, Eastern Europe

was the first and only region in the world to ex-perience a reduction of the population before 2000 (it grew at–0.38 per cent per year during 1995-2000). Northern Europe and Western Europe had somewhat higher rates of growth at the time (0.23 per cent), but in both of them population growth would have been considerably lower with-out the net influx of international migrants. In Western Europe, for instance, natural increase accounted only for one third of the growth in the region. By the end of the projection period, nega-tive growth rates are projected for all regions of Europe in the low and medium variants. In the high variant, only in Northern Europe is the growth rate expected to remain positive until 2045-2050 (see table V.8). In the medium variant, more substantial negative growth rates are pro-jected for Eastern Europe and Southern Europe in 2045-2050 (-0.8 per cent per year) than for North-ern Europe and Western Europe (-0.25 per cent and -0.38 per cent, respectively). In the case of Western Europe the projected growth rate would have been lower were it not for the effect of posi-tive net international migration which in 2045-2050 is expected to raise the growth rate by about 29 per cent.

As in the case of the major areas of the world,

the different patterns of growth at the regional level will result in different gains in population size over the projection period. Table V.11 shows the population of the major areas and regions from 1950 to 2050 according to the medium variant. During the entire period 1950-2050, two regions consistently have the largest number of inhabi-tants: Eastern Asia and South-central Asia. In 1950, Eastern Asia was the most populous region with 672 million inhabitants, surpassing South-central Asia’s population by nearly 35 per cent. But, because of the rapid fertility decline in East-ern Asia, by 2000 both regions had about the same number of inhabitants (1.5 billion) with the popu-

lation of South-central Asia slightly surpassing that of Eastern Asia. Hence, from 2000 to 2050, Eastern Asia’s population will become the second largest of the world. By 2050, South-central Asia is expected to have about 52 per cent more inhabi-tants than Eastern Asia (2.5 billion versus 1.7 bil-lion).

The third region of Asia, South-eastern Asia,

was also the third most populous region of the world in 2000 (with 0.5 billion inhabitants) and will remain so until 2050 when its population will reach nearly 0.8 billion, a 53 per cent increase from its 2000 level. The other regions that will have more than half a billion inhabitants in 2050 include South America and two regions in Africa, Eastern Africa and Western Africa. The popula-tion of South America is expected to rise from 346 million in 2000 to 536 million in 2050, a moderate increase of about 55 per cent. Sharper increases are recorded by the populations of East-ern Africa and Western Africa which will rise to 691 million and 608 million in 2050, but from a base population in 2000 of 250 million and 224 million respectively, so that in both cases the population will more than double over the projec-tion period. A very marked rise in population size will also take place in Middle Africa, consistent with its sustained high rate of growth over the projection period. The population of that region is expected to increase from 95 million in 2000 to 341 million in 2050, more than tripling over that period. Southern Africa provides a stark contrast to such rapid growth in the African continent. For that region, the expected population increase between 2000 and 2050 is from 50 to 57 million, equivalent to a relatively low increase of 14 per cent. For the most part, low fertility and high mor-tality associated with HIV/AIDS will be the cause of this relatively small increase.

Sizeable increases in population size are also

expected in Western Asia (a rise from 188 million persons in 2000 to 424 million in 2050); Northern Africa (174 million to 304 million); and Central America (135 million to 220 million). In the re-gions constituted mainly by small island coun-tries, population increases will also be robust but will not have a major impact on the rise of the world population. Nevertheless, it should be noted that the population of Melanesia is expected to

TABLE V.11. POPULATION OF THE MAJOR AREAS AND REGIONS OF THE WORLD FOR SE LECTED YEARS, MEDIUM VARIANT, 1950-2050 (Millions)

Major area or region 1950 1975 2000 2005 2010 2015 2020 2025 2030 2035 2040 2045 2050

World ............................................... 2 519 4 066 6 057 6 441 6 826 7 207 7 579 7 937 8 270 8 576 8 855 9 105 9 322

Europe.............................................. 548 676 727 721 713 705 695 684 670 655 639 622 603 Eastern Europe............................... 220 286 304 296 289 281 274 266 258 249 240 232 223 Northern Europe............................. 78 89 95 96 96 96 97 97 97 96 95 94 93 Southern Europe............................. 109 132 145 145 144 142 140 137 134 130 126 122 117 Western Europe.............................. 141 169 183 184 185 185 184 183 182 180 177 174 171

Northern America ............................ 172 243 314 328 342 356 370 384 396 408 418 428 438

Oceania............................................. 13 21 31 32 34 36 38 40 42 43 45 46 47 Australia/New Zealand .................. 10 17 23 24 25 26 27 28 29 29 30 30 31 Melanesia ....................................... 2 4 6 7 8 9 10 11 11 12 13 14 14 Micronesia...................................... 0 0 1 1 1 1 1 1 1 1 1 1 1 Polynesia........................................ 0 0 1 1 1 1 1 1 1 1 1 1 1

Africa ............................................... 221 406 794 892 997 1 110 1 231 1 358 1 489 1 620 1 750 1 879 2 000 Eastern Africa ................................ 65 124 250 283 318 358 401 447 495 544 595 644 691 Middle Africa................................. 26 45 95 111 129 150 173 199 227 256 286 314 341 Northern Africa.............................. 53 97 174 191 206 221 236 250 263 275 285 295 304 Southern Africa .............................. 16 29 50 52 52 52 52 52 52 53 54 55 57 Western Africa ............................... 60 110 224 256 291 330 370 411 452 492 530 570 608

Asia .................................................. 1 399 2 397 3 672 3 911 4 145 4 371 4 582 4 777 4 950 5 101 5 232 5 341 5 428 Eastern Asia ................................... 672 1 097 1 481 1 531 1 579 1 624 1 661 1 685 1 698 1 702 1 700 1 687 1 665 South-central Asia.......................... 498 880 1 481 1 611 1 740 1 863 1 981 2 095 2 203 2 301 2 388 2 468 2 539 South-eastern Asia ......................... 178 321 522 559 594 628 661 692 720 745 767 785 800 Western Asia.................................. 50 99 188 209 232 255 279 304 328 353 377 401 424

Latin America and the Caribbean .... 167 322 519 557 594 630 664 695 723 748 771 790 806 Caribbean ....................................... 17 27 38 40 42 43 45 46 48 48 49 50 50 Central America............................. 37 79 135 147 158 168 178 188 196 204 210 216 220 South America................................ 113 216 346 371 395 418 440 461 480 496 511 524 536


more than double, reaching 14 million in 2050 and that of the Caribbean is expected to increase by 32 per cent to reach 50 million in 2050.

The populations of both Northern America and

Australia/New Zealand will experience consider-able growth during the first half of the twenty-first century, each rising by at least a third. Thus, by 2050 Northern America is expected to have 438 million inhabitants and Australia/New Zealand 31 million. Very different prospects face the popula-tions of the regions of Europe, all of which are expected to decline between 2000 and 2050. Ac-cording to the medium variant, between 2000 and 2050 the reductions will be small for the popula-tion of Western Europe, which will decrease from 183 million to 171 million, and for that of North-ern Europe, which will decrease from 95 million to 93 million. A sharper decrease will occur in Eastern Europe and Southern Europe: the popula-tion of Eastern Europe will decline from 304 mil-lion in 2000 to 223 million in 2050; that of South-ern Europe will fall from 145 million to 117 million over the same period. These changes rep-resent a population loss of 27 per cent and 19 per cent, respectively.

Such changes in population size at the regional

level imply a redistribution of the world popula-tion among the different regions. As table V.12 shows, the proportions of the world population in the regions of Latin America and the Caribbean as well as those in those of Oceania and in Northern America will remain virtually unchanged between 2000 and 2050, but they will rise in Eastern Af-rica, Middle Africa and Western Africa, as well as in South-central Asia and Western Asia. The larg-est absolute increases will correspond to South-central Asia, whose share of the world population will grow from 25 per cent in 2000 to 27 per cent in 2050, and to Eastern Africa and Western Af-rica, whose shares will rise from about 4 per cent to around 7 per cent each over the same period.

In contrast, a decline is expected in the propor-

tion of the world population in the different re-gions of Europe as well as in Eastern Asia. The population of Eastern Asia, which in 2000 consti-tuted nearly a quarter of all people on earth, will drop to 18 per cent by 2050. In all other regions experiencing a reduction, it will amount to about

one percentage point, except in the case of Eastern Europe where the reduction will be of approxi-mately three percentage points. However, because the shares of the world population in the regions of Europe were already relatively low in 2000, the projected reductions will be substantial in relative terms.

D. THE DYNAMICS OF POPULATION GROWTH

AT THE COUNTRY LEVEL Global and regional trends do not reveal the di-

versity of population dynamics at the country level. In 2000-2005, according to the medium variant, population growth rates were expected to range from 5.5 per cent per year in Liberia (as a result of the projected repatriation of those dis-placed during recent conflicts) to –1.2 per cent per year in Estonia. According to the distribution of countries by the level of their growth rate, in 2000-2005 a total of 27 countries, constituting just 3.3 per cent of the world population in 2000, were expected to have a growth rate of 3 per cent or more (see table V.13). Most of the countries in this group are located in Africa or Asia. Growth rates in 50 other countries with 13.5 per cent of the world population were expected to range from 2 to 3 per cent. A total of 61 countries had growth rates ranging from 1 to 2 per cent; they were esti-mated to have 39.2 per cent of the world popula-tion in 2000. A further 35 per cent of the world population lived in the 64 countries whose growth rates ranged from 0 per cent to 1 per cent. Lastly, for 26 countries the growth rates were expected to be negative. The population of these countries constituted 9 per cent of the total for the world. Most of the countries experiencing negative growth are located in Europe, two are in Asia, two in the Caribbean and one in Oceania.

A useful indicator of the shape of a distribution

is the five-number summary. Table V.14 presents the five-number summaries for the distributions of the annual growth rates for each country or area in 1950-1955, 2000-2005 and 2045-2050 and figure V.5 displays them schematically. As the figure shows, between 1950-1955 and 2000-2005, the distribution of the growth rate by country became more compact and shifted downwards, especially in terms of its upper extreme which declined from a growth rate of 8.86 per cent per year to 5.53 per


TABLE V.12. DISTRIBUTION OF THE WORLD POPULATION BY MAJOR AREA A ND REGION, MEDIUM VARIANT, SELECTED YEARS, 1950-2050

(Percentage) Major area or region 1950 1975 2000 2005 2010 2015 2020 2025 2030 2035 2040 2045 2050

Europe................................ 21.8 16.6 12.0 11.2 10.4 9.8 9.2 8.6 8.1 7.6 7.2 6.8 6.5 Eastern Europe............... 8.7 7.0 5.0 4.6 4.2 3.9 3.6 3.4 3.1 2.9 2.7 2.5 2.4 Northern Europe............. 3.1 2.2 1.6 1.5 1.4 1.3 1.3 1.2 1.2 1.1 1.1 1.0 1.0 Southern Europe............. 4.3 3.3 2.4 2.3 2.1 2.0 1.8 1.7 1.6 1.5 1.4 1.3 1.3 Western Europe.............. 5.6 4.2 3.0 2.9 2.7 2.6 2.4 2.3 2.2 2.1 2.0 1.9 1.8

Northern America .............. 6.8 6.0 5.2 5.1 5.0 4.9 4.9 4.8 4.8 4.8 4.7 4.7 4.7

Oceania............................... 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Australia/New Zealand .. 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.3 0.3 0.3 0.3 0.3 Melanesia ....................... 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.2 Micronesia...................... 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Polynesia........................ 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

Africa ................................. 8.8 10.0 13.1 13.8 14.6 15.4 16.2 17.1 18.0 18.9 19.8 20.6 21.5 Eastern Africa ................ 2.6 3.1 4.1 4.4 4.7 5.0 5.3 5.6 6.0 6.3 6.7 7.1 7.4 Middle Africa................. 1.0 1.1 1.6 1.7 1.9 2.1 2.3 2.5 2.7 3.0 3.2 3.5 3.7 Northern Africa.............. 2.1 2.4 2.9 3.0 3.0 3.1 3.1 3.1 3.2 3.2 3.2 3.2 3.3 Southern Africa .............. 0.6 0.7 0.8 0.8 0.8 0.7 0.7 0.7 0.6 0.6 0.6 0.6 0.6 Western Africa ............... 2.4 2.7 3.7 4.0 4.3 4.6 4.9 5.2 5.5 5.7 6.0 6.3 6.5

Asia .................................... 55.5 58.9 60.6 60.7 60.7 60.6 60.4 60.2 59.8 59.5 59.1 58.7 58.2 Eastern Asia ................... 26.7 27.0 24.5 23.8 23.1 22.5 21.9 21.2 20.5 19.9 19.2 18.5 17.9 South-central Asia.......... 19.8 21.6 24.5 25.0 25.5 25.9 26.1 26.4 26.6 26.8 27.0 27.1 27.2 South-eastern Asia ......... 7.1 7.9 8.6 8.7 8.7 8.7 8.7 8.7 8.7 8.7 8.7 8.6 8.6 Western Asia.................. 2.0 2.4 3.1 3.3 3.4 3.5 3.7 3.8 4.0 4.1 4.3 4.4 4.5

Latin America and the Caribbean ......................... 6.6 7.9 8.6 8.6 8.7 8.7 8.8 8.8 8.7 8.7 8.7 8.7 8.6 Caribbean ....................... 0.7 0.7 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.5 0.5 Central America............. 1.5 1.9 2.2 2.3 2.3 2.3 2.4 2.4 2.4 2.4 2.4 2.4 2.4 South America................ 4.5 5.3 5.7 5.8 5.8 5.8 5.8 5.8 5.8 5.8 5.8 5.8 5.7 cent per year. The median also declined between 1950-1955 and 2000-2005. Both changes were largely the result of the decline of fertility that had taken place between 1950 and 2000. In fact, the central part of the distribution had also shifted to lower values so that, whereas in 1950-1955 half of the countries in the world were growing at rates ranging between 1.11 per cent and 2.55 per cent per year, by 2000-2005, the equivalent range had become 0.55 per cent to 2.33 per cent per year. The relatively high value for the upper quartile in 2000-2005 indicated that the fertility reductions were not that far advanced in many countries. But

by 2045-2050, the mid-range of the distribution is expected to have as limits –0.18 per cent and 0.89 per cent, implying that the growth rates among half the countries of the world will have a range of variation of about 1 per cent and will generally be low. In addition, the upper extreme of the distribution is expected to decline to 2.45 per cent, implying a sharp compression of the up-per part of the distribution and a marked reduction in growth rates. An important reduction of the lower extreme is also expected, since more coun-tries are projected to experience negative popula-tion growth. By 2045-2050, 25 per cent of all


TABLE V.13. DISTRIBUTION OF COUNTRIES AND POPULATION BY LEVEL OF GROWTH RATE IN 2000-2005 AND MAJOR AREA, MEDIUM VARIANT

Range of growth rate (percentage) Africa Asia Europe

Latin America and the

Caribbean Northern America Oceania World Percentage

Number of countries

3.0+ ........................... 11 7 1 5 0 3 27 11.8 2.0-2.99 ..................... 25 11 0 8 0 6 50 21.8 1.0-1.99 ..................... 14 20 4 17 0 6 61 26.6 0.0-0.99 ..................... 6 10 21 14 5 8 64 27.9 <0.0 ........................... 0 2 21 2 0 1 26 11.4

TOTAL 56 50 47 46 5 24 228 100.0

Population in 2000 (millions)

3.0+ ........................... 134 67 0 0 0 1 202 3.3 2.0-2.99 ..................... 397 374 0 41 0 5 817 13.5 1.0-1.99 ..................... 214 1 700 4 453 0 1 2 373 39.2 0.0-0.99 ..................... 49 1 509 200 25 314 23 2 121 35.0 <0.0 ........................... 0 21 522 0 0 0 544 9.0

TOTAL 794 3 672 727 519 314 31 6 057 100.0

TABLE V. 14. INDICATORS OF THE DIS TRIBUTION OF COUNTRIES OR AREAS BY LEVEL OF GROWTH RATE

IN 1950-1955, 2000-2005 AND 2045-2050 1950-1955 2000-2005 2045-2050

Upper extreme........ 8.86 5.53 2.45 Upper quartile ........ 2.55 2.33 0.89 Median ................... 1.98 1.32 0.45 Lower quartile ........ 1.11 0.55 -0.18 Lower extreme ....... -1.37 -1.15 -1.89

NOTE: The upper and lower extremes indicate the highest and lowest values observed; the lower quartile, the median and the upper quartile divide the distribution into four parts, each with the same number of observations. Consequently, half of the observed values fall between the two quartiles and the median is an indicator of the centre of the distribution. countries are expected to have growth rates rang-ing from –0.18 per cent per year to –1.89 per cent per year.

To provide a sense of the variability of growth rates today in relation to the diverse levels of fer-tility and mortality experienced by different coun-tries, figure V.6 presents a schematic plot of the crude birth rate against the crude death rate. The data are oriented and scaled in such a way that the diagonal lines indicate the level of natural in-crease that results from the birth rate and death

rate values plotted. Each point in the plot repre-sents a country. Plots are presented for the periods 2000-2005 and 2045-2050, according to the me-dium variant. The plot for 2000-2005 illustrates clearly the fact that at the present time countries are at different stages in the transition to low mor-tality and low fertility. Countries at early stages of the transition still have high birth rates and high death rates. As the transition proceeds, death rates are the first to decline, and the number of coun-tries with high birth rates and low death rates is large. However, as figure V.6 illustrates, a large cluster of countries with lower birth rates and low death rates is already present. As the transition proceeds, death rates increase owing to the ageing of the population so that countries tend to cluster over the area where natural increase is low or negative and death rates are moderate or high.

In comparison with the first plot in figure V.6, a

number of striking differences can be observed in the second plot, which refers to 2045-2050. In the first place, the variability in the points plotted has been reduced very markedly; furthermore, it is clear that countries tend to cluster at relatively low levels of natural increase. Nevertheless, by 2045-2050 the natural increase of countries will still


Figure V.5. Distribution of countries by annual growth rate, 1950-1955, 2000-2005 and 2045-2050

range from a value of –1.12 per cent to 2.5 per cent, a range that would appear quite broad were it not compared with the situation today. In addition, as the plot for 2045-2050 makes plain, for many countries the death rates will be fairly high, but the cause of those high values will no longer be high mortality. Instead, the increased death rates will be largely the result of the older age structure of the population. High death rates combined with low birth rates resulting from sustained low fertil-ity will be characteristic of about a third of the countries of the world. By 2045-2050, a total of 56 countries or areas will have negative rates of natural increase.

Not only is there great diversity among coun-

tries with respect to their levels of natural in-crease, but also in terms of their population size. As tables V.15 and V.16 show, in 2000 the ten most populous countries accounted for 60 per cent of the world population and had a combined population of more than 3.6 billion people. The two largest countries, China (1.28 billion) and India (1.01 billion), together represented 38 per cent of the Earth’s population. Seven of the ten most populous countries were in the less devel-oped regions, and the three in the more developed regions (the United States of America with 283 million; the Russian Federation with 145 million;

and Japan with 127 million) accounted for 9 per cent of the world population. The dominance of very populous countries has not changed substan-tially during past decades, nor is it expected to change significantly over the projection period. In 1950 the ten largest countries already accounted for 62 per cent of the world population, and it is projected that by 2050 the ten largest countries will represent 57 per cent of the 9.3 billion per-sons expected to live on Earth at that time.

In 2000, 13 countries had each a population

ranging from 50 million to 100 million, and as a group they accounted for about 15 per cent of the world population. An additional 25 countries, comprising 13 per cent of the world population, each had a population in the range of 20 million to 50 million. Most countries, however, had smaller populations. Nearly half of all countries (104), had each a population ranging from 1 million to 20 million in 2000, and 76 others had populations of under 1 million each. Taken together, these 180 countries accounted for about 13 per cent of the world population.

As noted above, the concentration of the world

population in a small number of populous coun-tries will not change much during the projection period. Table V.16 shows the number of countries

Figure V.6. Schematic plot of the components of natural increase for the countries of the world, medium variant, 2000-2005 and 2045-2050

2000-2005 2045-2050

0

10

20

30

40

50

60

0102030

Crude death rate (per thousand )

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thou

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0102030

Crude death rate (per thousand )

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TABLE V.15. DISTRIBUTION OF COUNTRIES AND POPULATION BY POPULATION SIZE IN 2000 AND MAJOR AREA, MEDIUM VARIANT

Range of population size Africa Asia Europe

Latin America and the

Caribbean Northern America Oceania World Percentage

Number of countries

100+ ................... 1 6 1 1 1 0 10 4.4 50-100 ................ 3 5 4 1 0 0 13 5.7 20-50 .................. 7 9 4 4 1 0 25 10.1 1-20 .................... 35 23 26 17 0 3 104 45.6 <1 ....................... 10 7 12 23 3 21 76 33.3 TOTAL 56 50 47 46 5 24 228 100.0

Population in 2000 (millions)

100+ ................... 114 2 902 145 170 283 0 3 615 59.7 50-100 ................ 182 354 258 99 0 0 892 14.7 20-50 .................. 224 252 151 129 31 0 786 13.0 1-20 .................... 270 161 172 117 0 28 747 12.3 <1 ....................... 4 4 2 4 0 3 17 0.3 TOTAL 794 3 672 727 519 314 31 6 057 100.0

accounting for 75 per cent of the world popula-tion, a number that increased from 21 to 24 be-tween 1950 and 2000 and will rise further to 29 in 2050 according to the medium variant. Through-out the period 1950-2050, China, India and the United States remain as the three most populous countries of the world, although China and India exchange places as the first and second most populous countries during the projection period. As time elapses a change occurs in the compos i-tion of the countries listed in table V.16: in 1950, a total of 10 out of the 21 countries accounting for three quarters of the world population were in the more developed regions; by 2000 the number of more developed countries had decreased to 8 even though the list had expanded to 24 and by 2050 only 5 of the more developed countries will rank among the 29 that are expected to account for three-quarters of the world population.

The populations of countries or areas with

smaller populations, that is, those with fewer than 140,000 inhabitants in 2000, were projected by making assumptions about future rates of growth and not by using the normal cohort-component method. The list of 41 countries or areas treated in this manner is presented in table V.17 together with their populations as estimated for 1950 and 2000 and as projected under the medium variant for 2050. In 2000 these 41 countries or areas had a

total population of 1.95 million people, represent-ing 0.03 per cent of the world population. The majority are small island States or areas with vul-nerable ecosystems and limited resources to sus-tain fast-growing populations. However, as a group, they are likely to have to contend with a 65 per cent increase of the population by 2050, when their total number of inhabitants is expected to rise to 3.22 million.

Just as the world population is concentrated in a

few populous countries, the quinquennial increase of world population is largely dependent on the increases recorded by a few countries. Table V.18 shows the countries where 75 per cent of the in-crease of world population is concentrated during the periods 1950-1955, 2000-2005 and 2045-2050 according to the medium variant. The number of countries involved varies little between 1950-1955 and 2000-2005, rising from 20 to 22, but by 2045-2050 it drops to 15 countries, primarily as a result of declining growth at the world level and the universal reduction of fertility to very low lev-els. Furthermore, there are important changes in the countries appearing in each list. In 1950-1955, for instance, 6 of the 20 countries making the largest contributions to population growth were located in the developed world, but by 2000-2005 and 2045-2050 only one of them is, the United States. In addition, whereas in 1950-1955 only

TABLE V.16. COUNTRIES ACCOUNTING FOR 75 PER CENT OF THE WORL D POPULATION BY ORDER OF POPULATION SIZE ACCORDING TO THE MEDIUM VARIANT, 1950, 2000 AND 2050

Country

Population in 1950

(thousands) Percentage Cumulated percentage Country

Population in 2000

(thousands) Percentage Cumulated percentage Country

Population in 2050

(thousands) Percentage Cumulated percentage

1 China 554 760 22 22 1 China 1 275 133 21 21 1 India 1 572 055 17 17 2 India 357 561 14 36 2 India 1 008 937 17 38 2 China 1 462 058 16 33 3 United States of America 157 813 6 42 3 United States of America 283 230 5 42 3 United States of America 397 063 4 37 4 Russian Federation 102 702 4 47 4 Indonesia 212 092 4 46 4 Pakistan 344 170 4 40 5 Japan 83 625 3 50 5 Brazil 170 406 3 49 5 Indonesia 311 335 3 44 6 Indonesia 79 538 3 53 6 Russian Federation 145 491 2 51 6 Nigeria 278 788 3 47 7 Germany 68 376 3 56 7 Pakistan 141 256 2 53 7 Bangladesh 265 432 3 50 8 Brazil 53 975 2 58 8 Bangladesh 137 439 2 56 8 Brazil 247 244 3 52 9 United Kingdom 50 616 2 60 9 Japan 127 096 2 58 9 Dem. Rep. of the Congo 203 527 2 55

10 Italy 47 104 2 62 10 Nigeria 113 862 2 60 10 Ethiopia 186 452 2 57 11 France 41 829 2 63 11 Mexico 98 872 2 61 11 Mexico 146 651 2 58 12 Bangladesh 41 783 2 65 12 Germany 82 017 1 63 12 Philippines 128 383 1 59 13 Pakistan 39 659 2 67 13 Viet Nam 78 137 1 64 13 Viet Nam 123 782 1 61 14 Ukraine 37 298 1 68 14 Philippines 75 653 1 65 14 Iran (Islamic Republic of) 121 424 1 62 15 Nigeria 29 790 1 69 15 Iran (Islamic Republic of) 70 330 1 66 15 Egypt 113 840 1 63 16 Spain 28 009 1 70 16 Egypt 67 884 1 67 16 Japan 109 220 1 64 17 Mexico 27 737 1 72 17 Turkey 66 668 1 69 17 Russian Federation 104 258 1 66 18 Viet Nam 27 367 1 73 18 Ethiopia 62 908 1 70 18 Yemen 102 379 1 67 19 Poland 24 824 1 74 19 Thailand 62 806 1 71 19 Uganda 101 524 1 68 20 Egypt 21 834 1 74 20 United Kingdom 59 415 1 72 20 Turkey 98 818 1 69 21 Turkey 20 809 1 75 21 France 59 238 1 73 21 United Rep. of Tanzania 82 740 1 70

22 Italy 57 530 1 74 22 Thailand 82 491 1 71 23 Dem. Rep. of the Congo 50 948 1 74 23 Afghanistan 72 267 1 71 24 Ukraine 49 568 1 75 24 Colombia 70 862 1 72 25 Germany 70 805 1 73 26 Myanmar 68 546 1 74 27 Sudan 63 530 1 74 28 France 61 832 1 75

29 Saudi Arabia 59 683 1 76


TABLE V.17. POPULATION OF COUNTRIES WITH LESS THAN 140,000 INHABITANTS IN 2000 FOR 1950, 2000 AND 2050

Country or area 1950 2000 2050

Africa 1 Saint Helena.............................................. 5 000 6 293 9 5642 Sao Tome and Principe............................. 60 000 137 707 293 8353 Seychelles.................................................. 34 000 80 411 145 192 Europe

4 Andorra ..................................................... 4 060 85 951 193 3455 Faeroe Islands ........................................... 31 713 46 232 54 8486 Gibraltar .................................................... 21 268 26 597 20 8537 Holy See.................................................... 1 000 780 7808 Isle of Man................................................ 55 845 75 144 80 7099 Liechtenstein ............................................. 13 648 32 640 38 573

10 Monaco...................................................... 20 180 33 420 37 75611 San Marino................................................ 15 000 26 514 30 005

Latin America and the Caribbean Caribbean

12 Anguilla..................................................... 5 200 11 410 22 65913 Antigua and Barbuda ................................ 46 300 64 848 73 16614 Aruba......................................................... 57 299 100 572 241 56015 British Virgin Islands ................................ 6 200 23 629 38 92316 Cayman Islands......................................... 6 300 38 231 89 25717 Dominica ................................................... 51 400 70 564 72 32518 Grenada ..................................................... 75 800 93 502 104 75019 Montserrat................................................. 13 500 3 749 10 75420 Saint Kitts and Nevis................................. 44 300 38 473 33 85521 Saint Vincent and Grenadines ................... 67 000 113 279 137 85222 Turks and Caicos Islands .......................... 5 000 16 699 38 60423 United States Virgin Islands ..................... 26 900 120 917 167 216

South America

24 Falkland Islands (Malvinas)...................... 2 249 2 317 3 515 Northern America

25 Bermuda .................................................... 37 252 62 960 79 25726 Greenland .................................................. 23 000 56 220 61 55927 Saint Pierre and Miquelon......................... 5 000 6 853 8 716

Oceania

28 American Samoa ....................................... 19 100 67 637 171 84129 Cook Islands.............................................. 14 708 19 612 26 65130 Kiribati ...................................................... 32 349 82 911 138 36131 Marshall Islands........................................ 12 805 51 137 84 71032 Micronesia (Fed. States of)....................... 32 203 122 725 268 55033 Nauru......................................................... 3 105 12 220 26 13634 Niue........................................................... 4 515 2 002 1 72535 Northern Mariana Islands.......................... 7 049 72 786 216 07936 Palau.......................................................... 5 562 19 178 38 58237 Pitcairn ...................................................... 130 68 6838 Tokelau...................................................... 1 572 1 452 1 45239 Tonga ........................................................ 41 335 99 039 125 09140 Tuvalu ....................................................... 4 657 10 175 16 32041 Wallis and Futuna Islands ........................ 7 059 14 462 19 133

TOTAL 920 563 1 951 316 3 224 127

TABLE V.18. COUNTRIES ACCOUNTING FOR 75 PER CENT OF WORLD POPULATION GROWTH ACCORDING TO THE MEDIUM VARIANT, 1950-1955, 2000-2005 AND 2045-2050

Country

Population increase

1950-1955 (thousands) Percentage

Cumulated percentage Country

Population increase


Cumulated percentage Country

Population increase


Cumulated percentage

1 China 54 245 23 23 1 India 79 644 21 21 1 India 31 805 15 15 2 India 37 535 16 39 2 China 46 231 12 33 2 Pakistan 17 273 8 23 3 United States of America 13 261 6 45 3 Pakistan 19 090 5 38 3 Dem. Rep. of the Congo 15 646 7 30 4 Brazil 8 912 4 48 4 Nigeria 15 860 4 42 4 Nigeria 14 824 7 37 5 Russian Federation 8 699 4 52 5 Bangladesh 15 113 4 46 5 Ethiopia 14 586 7 43 6 Indonesia 6 919 3 55 6 Indonesia 13 246 3 49 6 Yemen 11 808 5 49 7 Japan 6 190 3 58 7 United States of America 12 834 3 53 7 Uganda 9 306 4 53 8 Bangladesh 4 318 2 60 8 Brazil 10 680 3 55 8 Bangladesh 9 161 4 57 9 Pakistan 4 078 2 61 9 Dem. Rep. of the Congo 9 258 2 58 9 United States of America 9 137 4 61

10 Mexico 4 000 2 63 10 Ethiopia 8 055 2 60 10 Niger 5 828 3 64 11 Nigeria 3 535 2 64 11 Philippines 7 352 2 62 11 Indonesia 5 376 2 67 12 Philippines 3 226 1 66 12 Mexico 7 267 2 64 12 Angola 5 349 2 69 13 Thailand 3 133 1 67 13 Egypt 5 922 2 65 13 Afghanistan 4 990 2 71 14 Turkey 3 050 1 68 14 Viet Nam 5 260 1 67 14 Somalia 4 250 2 73 15 Egypt 2 858 1 70 15 Iran (Islamic Republic of) 5 036 1 68 15 United Rep. of Tanzania 4 185 2 75 16 Ukraine 2 801 1 71 16 Turkey 4 541 1 69 17 Viet Nam 2 686 1 72 17 Afghanistan 4 398 1 70 18 Poland 2 457 1 73 18 United Rep. of Tanzania 4 316 1 71 19 Iran (Islamic Republic of) 2 178 1 74 19 Yemen 4 135 1 72 20 Canada 1 999 1 75 20 Uganda 4 026 1 73

21 Sudan 3 792 1 74 22 Thailand 3 695 1 75


two countries on the list were located in Africa, by 2000-2005 seven of the countries included were in Africa, and their number increased to 8 by 2045-2050. Most of the countries in Africa expected to account for a large proportion of the population increment in 2045-2050 are those whose fertility is projected to remain well above replacement level in that period. Among the countries of Latin America, none remains on the list over the three periods, although Brazil and Mexico are on the list for 1950-1955 and 2000-2005. In all three pe-riods, India appears as one of the major contribu-tors to population growth, accounting for 16 per cent of the increase of world population in 1950-1955, 21 per cent in 2000-2005 and 15 per cent in 2045-2050. In contrast, China, which in 1950-1955 accounted for 23 per cent of world popula-tion growth and in 2000-2005 was still projected to contribute 12 per cent of that growth, is no longer on the list of major contributors to popula-tion growth in 2045-2050. The reason for the dis-appearance of China from that list is that by 2045-2050, according to the medium variant, China will be the country experiencing the largest reduction of population in absolute terms. Indeed, as table V.19 shows, the number of countries experiencing outright reductions of population will increase markedly from 2000-2005 to 2045-2050, and China heads the list for the latter period. The Rus-sian Federation occupies second place and is noteworthy for experiencing the largest loss of population in 2000-2005 in absolute terms. As table V.19 indicates, most of the countries experi-encing population declines in 2000-2005 are countries with economies in transition. By 2045-2050 those countries will be joined by most of the market-economy countries of Europe as well as by a number of countries of Eastern and South-eastern Asia that have already reached very low fertility levels, and by a few countries in the Car-ibbean.

E. THE CHANGING AGE DISTRIBUTION

OF THE WORLD POPULATION Although the process of transition from high

mortality and high fertility to low levels of both brings about profound changes in the distribution of the population by age, those changes occur slowly and take many years to become evident. In fact, the two major components of the transition

lead to different types of effects on the age distri-bution of the population. Initially, the reduction of mortality from high levels involves a very sub-stantial decline in the risk of dying at early ages (usually under age 5) so that the immediate effect of a decline in mortality is an increase in the num-ber of children in the population. Although mor-tality declines also have an impact at older ages, the effects on the age distribution of increases in longevity after ages 40 or 50 are normally more than counterbalanced by the sharp increases in the number of children surviving. Therefore, the first phase of the demographic transition leads to a younger age distribution than that prior to the transition.

Then, as fertility declines, the rate of increase in

the number of children begins to fall and the growth in the number of children decele rates. The deceleration comes about because parents have, on average, fewer children than their forebears. However, the number of parents is usually large in comparison with previous generations, so that even with lower average fertility they will have large numbers of offspring. Therefore, the number of children will increase over time, although not as fast as before the fertility decline started so that, if fertility reductions are maintained, the de-celeration of the growth of younger age groups will eventually give rise to outright reductions in the number of children. Hence, a sustained decline of fertility leads to a reduction of the younger co-horts of the population in relative terms and re-sults in population ageing.

The process of population ageing resulting from

fertility reductions is likely to be reinforced by further reductions of mortality. Indeed, once the expectation of life reaches the upper 60s or higher values, mortality in childhood is low compared to mortality at older ages and further reductions of mortality are likely to contribute more to an in-crease in the size of older cohorts than to an in-crease in the population of children. Conse-quently, a population with low fertility and declining mortality is likely to be ageing very fast.

In view of the above, the population of the

world is well on the way to becoming irreversibly older as a result of the changes in fertility and mortality that have taken place over the past cen-


TABLE V.19. COUNTRIES EXPERIENCING REDUCTIONS OF POPULATION IN 2000-2005 OR 2045-2050, MEDIUM VARIANT (Thousands)

Country or area Population decrement

in 2000 -2005 Country or area Population d ecrement

in 2045 -2050

1 Russian Federation -4 571.3 1 China -18 874.02 Ukraine -2 269.8 2 Russian Federation -4 370.83 Bulgaria - 379.7 3 Japan -3 255.44 Italy - 365.0 4 Italy -2 166.95 Kazakhstan - 296.6 5 Ukraine -1 937.26 Romania - 287.4 6 Germany -1 867.67 Hungary - 247.0 7 Spain -1 521.08 Belarus - 203.0 8 Poland - 799.59 Poland - 178.5 9 United Kingdom - 742.3

10 Germany - 156.8 10 Republic of Korea - 638.311 Georgia - 137.8 11 Romania - 538.112 Yugoslavia - 77.7 12 France - 508.713 Estonia - 77.2 13 Cuba - 331.114 Latvia - 67.2 14 Bulgaria - 303.915 Sweden - 57.1 15 Kazakhstan - 285.416 Republic Of Moldova - 56.3 16 Czech Republic - 276.517 Czech Republic - 53.4 17 Greece - 276.018 Lithuania - 43.4 18 Austria - 272.319 Austria - 38.4 19 Hungary - 249.220 Spain - 35.9 20 Switzerland - 246.121 Switzerland - 22.4 21 Georgia - 243.022 Slovenia - 11.7 22 Belarus - 240.624 Saint Kitts And Nevis - 1.3 23 Portugal - 228.825 Dominica - 0.3 24 Netherlands - 228.826 Gibraltar - 0.2 25 Yugoslavia - 225.027 Niue - 0.1 26 Bosnia and Herzegovina - 164.4

27 Belgium - 160.4 28 Slovakia - 159.2 29 Armenia - 153.7 30 Sri Lanka - 151.8 31 Sweden - 144.3 32 Singapore - 140.9 33 Azerbaijan - 119.3 34 Republic of Moldova - 107.9 35 Lithuania - 93.3 36 Finland - 91.3 37 Croatia - 76.3 38 Denmark - 75.9 39 Slovenia - 70.9 40 Latvia - 65.5 41 Estonia - 59.0 42 Guyana - 50.0 43 TFYR Macedonia - 45.1 44 Trinidad and Tobago - 27.2 45 Fiji - 23.2 46 Suriname - 10.0 47 Andorra - 8.3 48 Barbados - 8.0 49 Guadeloupe - 7.6 50 Martinique - 5.7 51 China, Macau SAR - 5.5 52 Channel Islands - 4.9 53 Malta - 4.8 54 Norway - 3.5 55 Cyprus - 2.7 56 Mauritius - 2.2 57 San Marino - 1.3 58 Isle of Man - 1.1 59 Gibraltar - 0.9 60 Netherlands Antilles - 0.8 61 Faeroe Islands - 0.8 62 Liechtenstein - 0.8 63 Monaco - 0.8

64 Saint Lucia - 0.2


tury and those expected in the future. Figure V.7 illustrates the past and future dynamics of the age-ing process by displaying the changing growth rates of different age groups of the population ac-cording to past estimates and the medium variant. The growth rate of the total population is also plotted for reference purposes. As expected, the 0-14 age group, representing the age group of “chil-dren”, shows a high growth rate until 1960 before a decline sets in. Although the decline has not been smooth, influenced as it is by the timing of the demographic transition in different regions, it nevertheless has put the growth rate of the number of children well below the average growth rate of the population as a whole from 1970 onwards and will lead to almost zero growth rates among chil-dren from 2030 to 2050. In contrast, the growth rates of age groups 15-59 and 60 or over have been higher than that of the population as a

whole since 1970 and that of age group 60 or over is expected to remain high until 2050. By the early part of the twenty-first century, the growth of the age group 15-59 will be decelerating, whereas that of the older population will enter a phase of rapid acceleration until it reaches a level of about 3 per cent per year in 2010-2015 and maintains it until 2020-2025. Although the rate of increase of the population aged 60 years or over declines mark-edly after 2030, by the end of the projection pe-riod it will still be 1.6 per cent per year, whereas the growth rate of age group 0-14 will be negative and that of age group 15-59 will be just above 0.2 per cent per year.

Over time, those distinct patterns of growth by

age group lead to a major change in the age distri-bution of the world population. Between 2000 and 2050, the proportion of children (i.e., persons

Figure V.7. Annual growth rates for age groups 0-14, 15-59 and 60 or over: past estimates and medium variant, 1950-2050

-0.5

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

1950-1

955

1955-1

960

1960-1

965

1965-1

970

1970-1

975

1975-1

980

1980-1

985

1985-1

990

1990-1

995

1995-2

000

2000-2

005

2005-2

010

2010-2

015

2015-2

020

2020-2

025

2025-2

030

2030-2

035

2035-2

040

2040-2

045

2045-2

050

Period

Ann

ual g

row

th ra

te (

perc

enta

ge)

0-14 15-59 60 or over Total


aged 0 to 14) will decline from 30 per cent to 21 per cent, while the proportion of older persons (60 years or over) is expected to rise from 10 per cent to 21 per cent. The proportion of adults (15-59) is expected to decrease slightly from 60 per cent in 2000 to 58 per cent in 2050. The very sharp in-crease in the proportion of older persons has a number of implications. Although in 2000 there were 1.8 billion children and 0.6 billion older per-sons, by 2050 the number of children will be slightly lower than that of older persons (1.95 bil-lion versus 1.96 billion). In terms of five-year age groups, these transformations imply that the typi-cal pyramidal shape of the age composition, char-acterized by a broad base and a narrow top, will become almost rectangular by 2050. However, as figure V.8 illustrates, the different projection vari-ants result in quite different age distributions by 2050. Although there is significant population ageing according to the three variants displayed, the high variant produces an age distribution with a pyramidal shape because it has a positive rate of growth, with the base narrower than it is for 2000 and the top broader, but with the number of chil-dren still larger than the older population. The medium variant produces the quasi-rectangular shape that has already been described and the low variant produces a shape that resembles an “in-verted pyramid”, with a very narrow base and a broad top, typical of decreasing populations with low fertility and low mortality levels.

F. POPULATION AGEING AT THE

REGIONAL LEVEL A useful indicator of the age composition of

populations is the median age, that is, the age at which 50 per cent of the population is older and 50 per cent is younger than that age. Table V.20 displays the median age for the world and its ma-jor areas and regions for the years 1950, 2000 and 2050 in the high, medium and low variants as well as in the zero-migration and constant-mortality scenarios. The increasing trend of the median age at the world level reflects the ageing of the popu-lation. Whereas in 1950 half of the population of the world was older than 23.6 years, by 2000 half of the population is estimated to be older than 26.5 years, and it is expected that in 2050 half of the population will be concentrated above age 36.2, according to the medium variant. Even the

high variant, which produces a smaller concentra-tion of the population in the older ages, yields a median age of 31.9 years in 2050, 5.4 years higher than that estimated in 2000. Interestingly, the con-stant-mortality scenario produces virtually the same median age in 2050 as the medium variant (35.8 years), implying that the changes in morta l-ity projected after 2000 have only a small effect on population ageing at the world level.

The more developed regions, being further

ahead in the transition to low fertility and low mortality, are also more advanced in the process of population ageing than the less developed re-gions as a whole. Thus, by 2000 the more devel-oped regions already had a median age higher than that expected for the world as whole in 2050 according to the medium variant (37.4 years ver-sus 36.2 years). By 2050, the median age in the more developed regions is expected to range from 42.2 years in the high variant to 50.3 years in the low variant, both of which imply a very marked ageing of the population. In the medium variant, the median age rises to 46.4 years, a figure 1.5 years lower than it would have been if migration from 2000 to 2050 were zero and 3 years higher than it would have been if mortality at the country level were to remain constant over 2000-2050 at the level it had in 1995-2000. That is, in the case of the more developed regions, the projected lev-els of international migration contribute to reduce somewhat population ageing and the projected increase in life expectancy contributes to accele r-ate population ageing to a significant extent.

Less developed regions as a whole display me-

dian ages that are closer to the world average and are considerably lower than those of the more de-veloped regions. By 2000, the median age in those regions is estimated to be 24.3 years, but by 2050 it will experience a sharper rise than the median age of the world. Even the high variant produces a median age of 30.8 years for the less developed regions, an increase of 6.5 years from the level in 2000. In the medium variant the median age rises to 35 years, and in the low variant it reaches a high of 40.2 years. In the less developed regions as a whole, international migration has virtually no effect on population ageing and the increase in life expectancy projected in the medium variant has only a minimal effect in accelerating popula-

Figure V.8. Age composition of the world population in 2000 and 2050 (low, medium and high variants)

2050 (low variant)

6 0 0 5 0 0 4 0 0 3 0 0 2 0 0 1 0 0 0 1 0 0 2 0 0 3 0 0 4 0 0 5 0 0 6 0 0

0 - 4

1 0 - 1 4

2 0 - 2 4

3 0 - 3 4

4 0 - 4 4

5 0 - 5 4

6 0 - 6 4

7 0 - 7 4

8 0 - 8 4

9 0 - 9 4

1 0 0 +

Thousands

Males Females

2000

6 0 0 5 0 0 4 0 0 3 0 0 2 0 0 1 0 0 0 1 0 0 2 0 0 3 0 0 4 0 0 5 0 0 6 0 0

0 - 4

1 0 - 1 4

2 0 - 2 4

3 0 - 3 4

4 0 - 4 4

5 0 - 5 4

6 0 - 6 4

7 0 - 7 4

8 0 - 8 4

9 0 - 9 4

1 0 0 +

T h o u s a n d s

Males Females

2050 (medium variant)

6 0 0 5 0 0 4 0 0 3 0 0 2 0 0 1 0 0 0 1 0 0 2 0 0 3 0 0 4 0 0 5 0 0 6 0 0

0 - 4

1 0 - 1 4

2 0 - 2 4

3 0 - 3 4

4 0 - 4 4

5 0 - 5 4

6 0 - 6 4

7 0 - 7 4

8 0 - 8 4

9 0 - 9 4

1 0 0 +

Thousands

Males Females

2050 (high variant)

6 0 0 5 0 0 4 0 0 3 0 0 2 0 0 1 0 0 0 1 0 0 2 0 0 3 0 0 4 0 0 5 0 0 6 0 0

0 - 4

1 0 - 1 4

2 0 - 2 4

3 0 - 3 4

4 0 - 4 4

5 0 - 5 4

6 0 - 6 4

7 0 - 7 4

8 0 - 8 4

9 0 - 9 4

1 0 0 +

Thousands

Males Females


TABLE V.20. M EDIAN AGE OF THE POP ULATION BY MAJOR AREA AND REGION, 1950, 2000 AND 2050

2050

Difference with medium variant

in 2050

Major area or region 1950 2000 High Medium Low Zero

migration Constant mortality

Zero migration

Constant mortality

World ............................................... 23.6 26.5 31.9 36.2 41.5 36.2 35.8 0.0 -0.4

More developed regions................... 28.6 37.4 42.2 46.4 50.3 47.9 43.4 1.5 -3.0 Less developed regions .................... 21.4 24.3 30.8 35.0 40.2 35.0 34.8 0.0 -0.1

Least developed countries ............ 19.5 18.2 24.0 26.5 29.5 26.6 27.4 0.1 0.8 Less developed regions without the least developed countries .... 21.6 25.3 33.1 37.9 43.8 37.9 37.1 0.0 -0.8

Europe............................................. 29.2 37.7 45.9 49.5 52.7 49.9 46.0 0.5 -3.5 Eastern Europe............................. 26.4 36.5 45.8 49.6 53.1 49.8 45.0 0.2 -4.6 Northern Europe........................... 33.5 37.7 43.5 47.3 50.7 47.3 44.2 0.0 -3.1 Southern Europe........................... 27.5 38.2 49.0 52.2 55.1 52.0 49.7 -0.2 -2.5 Western Europe............................ 34.5 39.0 45.0 48.5 51.7 49.9 45.5 1.4 -2.9

Northern America ............................ 29.8 35.6 36.5 41.0 45.4 43.1 39.0 2.1 -2.0

Oceania............................................. 27.9 30.9 34.6 38.1 41.7 38.5 37.0 0.4 -1.1 Australia/New Zealand ................ 30.2 35.0 38.8 42.2 45.3 44.5 40.7 2.4 -1.5 Melanesia ..................................... 19.6 19.8 28.6 31.7 35.2 31.6 30.6 -0.1 -1.2 Micronesia.................................... 20.7 21.1 29.5 33.4 37.9 33.4 32.3 0.1 -1.1 Polynesia...................................... 17.1 22.1 31.1 35.8 41.5 35.3 34.0 -0.5 -1.8

Africa ............................................... 19.0 18.4 24.8 27.4 30.5 27.5 28.3 0.0 0.9 Eastern Africa .............................. 18.2 17.1 23.4 25.6 28.3 25.6 26.2 0.0 0.6 Middle Africa............................... 19.4 16.3 22.2 24.1 26.5 24.1 24.9 0.0 0.8 Northern Africa............................ 19.3 21.7 31.9 36.7 42.8 36.7 36.1 0.0 -0.6 Southern Africa ............................ 20.7 22.1 27.1 31.1 36.5 31.1 33.1 0.0 2.0 Western Africa ............................. 19.0 17.3 25.0 27.6 30.6 27.6 28.6 0.0 1.0

Asia .................................................. 22.0 26.2 33.4 38.3 44.2 38.3 37.4 0.0 -0.9 Eastern Asia ................................. 23.5 30.8 39.2 44.3 50.5 44.3 41.8 0.0 -2.5 South-central Asia........................ 20.7 22.6 31.2 36.1 41.8 36.2 36.0 0.1 -0.1 South-eastern Asia ....................... 20.4 23.9 32.7 37.9 44.8 37.9 36.7 0.0 -1.2 Western Asia................................ 20.4 22.1 28.1 31.4 35.2 31.4 31.2 0.0 -0.2

Latin America and the Caribbean .... 20.1 24.4 32.6 37.8 44.4 37.6 36.6 -0.3 -1.2 Caribbean ..................................... 21.3 26.5 33.4 38.3 44.1 37.7 37.5 -0.6 -0.8 Central America........................... 18.8 22.4 32.5 37.8 44.3 37.1 36.9 -0.7 -0.9 South America.............................. 20.4 25.1 32.5 37.8 44.5 37.8 36.5 0.0 -1.3

tion ageing. As discussed in more detail below, this outcome stems from the diverse trends ex-pected in different groups of developing countries, which cancel out the effects of declining morta l-ity.

The group of least developed countries includes

most of the countries where the transition to lower mortality started rather late and where the transi-

tion to low fertility has barely begun. As a result, by 2000 they had not yet experienced any popula-tion ageing. Instead, the median age of the group declined from 19.5 years in 1950 to 18.2 years in 2000. The delayed transition that these countries have experienced so far will also delay population ageing, so that their median age will rise only moderately by 2050, reaching 26.5 years in the medium variant. In the least developed countries,


the projected net migration levels in the medium variant are responsible for reducing the median age by 0.1 years, implying that without migration the projected population in 1950 would have been very slightly older. More interestingly, the con-stant-mortality scenario produces also an older population for the least developed countries in 2050 because, in comparison with the medium variant, constant-mortality assumptions do not reflect the increases in mortality levels among adults projected in countries affected by HIV/AIDS. Thus, by 2050 the population pro-duced by the medium variant has a lower percent-age of persons in ages 15-59 than that produced by the constant-mortality scenario (61.4 per cent vs. 63.6 per cent) and that difference leads to a younger population than that produced by con-stant mortality. In fact, it is because of the inclu-sion of the least developed countries that the less developed regions as a whole exhibit almost no difference between the median age for 2050 pro-duced by the medium variant and that produced by the constant-mortality scenario. As table V.20 indicates, when the least developed countries are excluded from the less developed regions, the constant-mortality scenario produces a younger population than the medium variant, as it would normally be expected.

In terms of major areas, the populations of the

regions of Europe display the highest median ages among all the regions of the world during 2000 and 2050. For Europe as a whole the median age is projected to rise from 37.7 years in 2000 to 49.5 years in 2050 according to the medium variant. In all projection variants, Southern Europe is ex-pected to have the highest median age in 2050, amounting to 52.2 years according to the medium variant. Eastern Europe has the second highest median age according to the low, medium and high variants but, under the zero-migration and the constant-mortality scenarios, the median age of Western Europe in 2050 is greater than that of Eastern Europe. That is, the effect of the positive net international migration projected for Western Europe is to slow population ageing, as indicated by the fact that the median age in 2050 under the zero-migration scenario is 1.4 years higher than that produced by the medium variant. The con-stant-mortality scenario reduces population ageing in all of Europe’s regions, but the reduction of the

median age is especially marked in the case of Eastern Europe where mortality is higher in 1995-2000 than in other European regions.

Northern America and Australia/New Zealand

are projected to have somewhat lower median ages (in the range of 41 years to 42 years) than Europe in 2050. Just as in the case of Western Europe, the international migration gains pro-jected under the medium variant contribute to make the population younger in 2050, reducing the median age by 2.1 years in relation to that of the zero-migration scenario in Northern America and by 2.4 years in Australia/New Zealand. In addition, the further reductions of mortality pro-jected in the medium variant accelerate ageing and produce a median age in 2050 that is 2 years higher than that yielded by the constant-mortality scenario in Northern America and 1.5 years higher in Australia/New Zealand.

Among the less developed regions, only Eastern

Asia is expected to attain a median age above 40 years by 2050 in the medium variant. In fact, Eastern Asia is projected to have a median age of 44.3 years at that time, higher than that projected for Northern America. Regions whose median age in 2050 is expected to range from 35 years to 40 years according to the medium variant include the Caribbean, Central America, South America, South-central Asia, South-eastern Asia, Northern Africa and Polynesia. In all these regions, the con-stant-mortality scenario produces a younger popu-lation than the medium variant in 2050, and for the Caribbean, Central America and Polynesia, international migration losses lead to a slightly older population in 2050 than it would have been if net international migration were zero.

In all the regions of sub-Saharan Africa as well

as in Melanesia and Micronesia, the medium vari-ant produces median ages in 2050 lower than 35 years (ranging between 24.1 years to 33.4 years). That is, it is expected that by mid-century, the populations of these regions will be among the youngest on earth. In sub-Saharan Africa, the higher mortality of adults associated with HIV/AIDS contributes to delay population ageing, at least as measured in terms of the median age. Thus the medium variant produces a lower me-dian age than the constant-mortality scenario.


Trends in the median age at the regional level reflect the shifts in the distribution of countries by the median age. Table V.21 displays the five-number summaries of that distribution in 1950, 2000 and 2050 according to the medium variant. Between 1950 and 2000, the range of the distribu-tion expanded, as the lower extreme in 2000 be-came lower than in 1950 and the upper extreme in 2000 became higher than in 1950, indicating the greater heterogeneity of countries in terms of the different stages they had reached in the transition to low mortality and low fertility. Between 2000 and 2050, the distribution is expected to shift to higher values, starting with the lower quartile. As a consequence of this shift, whereas in 2000, three-quarters of the countries or areas of the world had a median age of at most 32.4 years, by 2050, three-quarters are expected to have a me-dian age greater than 31.2 years. In 2050, the countries with the youngest populations will have median ages ranging from 20.4 years to 31.2 years, levels similar to those characterizing the “older” populations of 1950. At the other end of the spectrum, a quarter of all countries will have median ages ranging from 44.5 years to 55.2 years, meaning that half of their populations will be middle-aged or older, an unprecedented condi-tion in human history.

As pointed out earlier, the process of population

ageing results mostly from a reduction of fertility. Indeed, the timing of fertility declines has impor-tant implications for the population age distribu-tion. Table V.22 presents the distribution of the

TABLE V.21. CHANGING DISTRIBUTION OF COUNTRIES ACCORDING TO MEDIAN AGE, MEDIUM VARIANT,

1950, 2000 AND 2050

1950 2000 2050

Upper extreme............ 35.8 41.2 55.2 Upper quartile ............ 24.8 32.4 44.5 Median ....................... 20.6 23.3 38.0 Lower quartile ............ 18.9 18.3 31.2 Lower extreme ........... 16.5 15.0 20.4

NOTE: The upper and lower extremes indicate the highest and lowest values observed; the lower quartile, the median and the upper quartile divide the distribution into four parts, each with the same number of observations. Consequently, half of the observed values fall between the two quartiles and the median is an indicator of the centre of the distribution.

187 countries with at least 140,000 inhabitants in 2000 grouped according to the stage they have reached in the transition to low fertility (see chap-ter I) and various indicators of the age distribution for those groups, namely, percentages of children aged 0-14, of elderly persons aged 60 or over, and of persons aged 80 or over (the “oldest old”) in addition to the median age. The table shows the striking differences existing today and expected in the future in the age distributions of those groups of countries. In general, the more advanced the stage reached in the transition to low fertility, the lower the percentage of children in the population, the higher the percentage of elderly persons and the higher the median age. Thus, in 2000, children constituted 47.8 per cent of the population in countries where the fertility transition had not be-gun as yet, whereas they accounted for a low 18.6 per cent of the population in countries that had embarked on the transition early in the twen-tieth century. Similarly, elderly persons aged 60 years or over comprised 4.4 per cent of the popu-lation in the “no transition” group, whereas they accounted for 19.3 per cent of the population of countries where the transition started early. More-over, the median age of the “no transition” coun-tries was a low 16 years in 2000 whereas that of the countries with an early transition was 37.1 years, more than twice as high. For the groups of countries in the intermediate stages of the transition, the values of these parameters fell between those of these two groups.

The relationship between the stage reached in the transition to low fertility and the extent of population ageing is expected to continue over the next fifty years. Thus, by 2050, the “no transit ion” countries are expected to have the highest propor-tion of children in their populations (33.8 per cent) and the lowest median age (23.5 years), whereas the “early transition” countries are ex-pected to have the lowest proportion of children (15.7 per cent) and the highest median age (46 years, twice as high as that of the “no trans i-tion” group). Nearly one third of the population of the “early transition” countries will be aged 60 years or over in comparison with 6.4 per cent in the “no transition” countries. The group of coun-tries with a total fertility in 1995-2000 ranging between 3 children and 4 children will likely have


TABLE V.22. ESTIMATED AND PROJECTED PERCENTAGES OF THE POPULATION IN SE LECTED AGE GROUPS AND MEDIAN

AGE FOR COUNTRIES GROUPED ACCORDING TO THEIR CURRENT STAGE IN THE TRANSITION TO LOW FERTILITY

Stage of transition to low fertility 2000 2050

Percentage under age 15

No transition............................... 47.8 33.8 Decline but TF still >5............... 43.8 26.2 Decline to 4<TF<=5................... 41.6 23.2 Decline to 3<TF<=4................... 34.6 20.1 Decline to 2.1<TF<=3................ 31.3 19.8 Decline to TF<=2.1.................... 24.8 16.4 Early transition........................... 18.6 15.7

Percentage aged 60 or over


Percentage aged 80 or over


Median age (years)


about 20 per cent of their population constituted of children and a median age of 37.3 years. That is, although between 2000 and 2050, population ageing will occur in all countries, it will be more marked in those countries that have already reached more advanced stages of the transition to low fertility.

G. THE IMPLICATIONS OF AGEING POPULATIONS

As the age distribution of a population is trans-

formed during the ageing process, not only do the relative weights of different age groups change but also certain relations between the different groups, relations that have been found useful in assessing the likely economic and social implica-tions of the universal shift to older ages. This sec-tion will focus on the expected changes in de-pendency ratios. However, before proceeding, it is useful to establish the types of changes expected in the age distribution of populations at the re-gional level. The results of the medium variant will be used here as the basis for discussion.

Tables V.23 and V.24 display the number and

percentage of persons in age groups 0-14, 15-59 and 60+ in 2000 and 2050 according to the me-dium variant, for the world and its major areas and regions. As expected, there are stark differences between the more developed and the less devel-oped regions. The proportion of older persons in the more developed regions is expected to in-crease from 19.4 per cent in 2000 to 33.5 per cent in 2050. In the less developed regions the increase will be larger in relative terms, from 7.7 per cent to 19.3 per cent, but by 2050 the concentration of population at ages 60 or over will still be lower than in the more developed regions. The less de-veloped regions will experience almost no change in the proportion of the population in the age group 15-59 (59.5 per cent versus 59 per cent), whereas for the more developed regions that pro-portion will decline considerably, passing from 62.3 per cent in 2000 to 51.0 per cent in 2050. In contrast, the proportion of children will not change much in the more developed regions (passing from 18.3 per cent in 2000 to 15.5 per cent in 2050), but will drop by more than a third in the less developed regions, decreasing from 32.8 per cent to 21.8 per cent.

As a result of these changes, the ratio of the number of persons aged 0-14 to that of persons aged 15-59 (the child-adult ratio) will increase slightly in the more deve loped regions whereas that of the number persons aged 60 or over to the


TABLE V.23. AGE COMPOSITION OF THE POPULATION BY BROAD AGE GROUP, MAJOR AREA AND REGION, MEDIUM VARIANT, 2000

Population (thousands) Percentage

Sex ratio (males per 100 females)

Major area or region 0-14 15-59 60+ 0-14 15-59 60+ 0-14 15-59 60+

World ................................................... 1 814 525 3 636 405 605 785 30.0 60.0 10.0 105.6 103.3 81.2

More developed regions....................... 217 944 742 043 231 442 18.3 62.3 19.4 105.1 100.5 70.7 Less developed regions ........................ 1 596 581 2 894 362 374 343 32.8 59.5 7.7 105.7 104.0 88.4

Least developed countries ................ 283 865 342 160 32 167 43.1 52.0 4.9 102.6 100.5 86.7 Less developed regions without the least developed countries ........ 1 312 715 2 552 202 342 176 31.2 60.7 8.1 106.4 104.5 88.5

Europe.................................................. 127 040 452 949 147 315 17.5 62.3 20.3 105.1 100.1 67.4 Eastern Europe................................ 55 032 192 491 56 650 18.1 63.3 18.6 104.7 97.2 58.3 Northern Europe.............................. 17 988 57 739 19 349 18.9 60.7 20.4 105.1 102.1 74.5 Southern Europe.............................. 22 881 90 433 31 621 15.8 62.4 21.8 106.0 100.9 75.3 Western Europe............................... 31 139 112 286 39 695 17.0 61.3 21.7 105.2 103.3 72.0

Northern America ................................ 67 417 195 802 50 894 21.5 62.3 16.2 104.9 101.1 76.0

Oceania................................................. 7 753 18 684 4 083 25.4 61.2 13.4 106.2 102.8 84.5 Australia/New Zealand ................... 4 794 14 407 3 715 20.9 62.9 16.2 105.5 101.1 83.1 Melanesia ........................................ 2 548 3 643 292 39.3 56.2 4.5 107.6 108.4 100.3 Micronesia....................................... 199 281 35 38.7 54.5 6.8 106.2 109.5 100.0 Polynesia......................................... 212 353 41 35.0 58.2 6.8 106.3 112.4 91.2

Africa ................................................... 338 192 415 344 40 091 42.6 52.3 5.1 101.9 99.8 83.1 Eastern Africa ................................. 113 312 125 824 11 182 45.3 50.3 4.5 100.8 98.4 83.6 Middle Africa.................................. 44 999 45 765 4 639 47.2 48.0 4.9 100.7 97.6 79.8 Northern Africa............................... 62 084 101 242 10 824 35.6 58.1 6.2 104.4 102.6 85.0 Southern Africa ............................... 17 334 29 419 2 813 35.0 59.4 5.7 100.8 98.2 67.8 Western Africa ................................ 100 462 113 094 10 633 44.8 50.4 4.7 102.3 100.3 86.8

Asia ...................................................... 1 110 563 2 239 631 322 147 30.2 61.0 8.8 107.2 105.6 88.8 Eastern Asia .................................... 353 284 960 838 166 952 23.9 64.9 11.3 110.6 105.8 87.9 South-central Asia........................... 520 584 855 792 104 492 35.2 57.8 7.1 106.5 107.4 92.2 South-eastern Asia .......................... 169 126 315 680 37 315 32.4 60.5 7.1 103.4 100.2 84.6 Western Asia................................... 67 568 107 321 13 388 35.9 57.0 7.1 104.4 106.4 86.3

Latin America and the Caribbean ........ 163 560 313 994 41 254 31.5 60.5 8.0 103.7 97.7 81.7 Caribbean ........................................ 11 198 22 995 3 748 29.5 60.6 9.9 103.8 98.4 86.6 Central America.............................. 47 096 79 032 9 000 34.9 58.5 6.7 104.1 97.1 85.6 South America................................. 105 266 211 967 28 505 30.4 61.3 8.2 103.6 97.9 79.9

number of persons aged 15-59 (the older persons-adult ratio) will be multiplied by a factor of two (see table V.25). Consequently, the overall de-pendency ratio in the more developed regions (i.e., the sum of the population aged 0-14 and that aged 60 or over divided by the population aged 15-59) will increase markedly, rising from 61 de-pendants per 100 adults in 2000 to 96 dependants per 100 adults in 2050. The less developed re-

gions will experience only a slight increase of the overall dependency ratio (passing from 68 de-pendants per 100 adults to 70 dependants per 100 adults) but the distribution of dependants will change. By 2050 the number of persons aged 60 years or over will be nearly as large as the number of children under age 15, whereas in 2000 the number of older persons was about a quarter of the number of children.


TABLE V.24. AGE COMPOSITION OF THE POPULATION BY BROAD AGE GROUP, MAJOR AREA AND REGION, MEDIUM VARIANT, 2050

Population (thousands) Percentage

Sex ratio (males per 100 females)

Major area or region 0-14 15-59 60+ 0-14 15-59 60+ 0-14 15-59 60+

World ................................................... 1 954 569 5 403 916 1 963 767 21.0 58.0 21.1 104.6 103.7 85.0

More developed regions....................... 183 487 602 515 395 106 15.5 51.0 33.5 105.4 103.4 78.2Less developed regions ........................ 1 771 082 4 801 401 1 568 660 21.8 59.0 19.3 104.5 103.8 86.8

Least developed countries ................ 533 255 1 123 065 173 222 29.1 61.4 9.5 102.7 101.6 90.6Less developed regions without the least developed countries ........ 1 237 827 3 678 336 1 395 438 19.6 58.3 22.1 105.3 104.4 86.3

Europe.................................................. 84 143 298 106 221 079 13.9 49.4 36.6 105.7 104.3 76.9 Eastern Europe................................ 31 344 109 440 81 956 14.1 49.1 36.8 105.4 102.5 70.2 Northern Europe.............................. 14 108 47 232 31 461 15.2 50.9 33.9 105.4 104.5 82.6 Southern Europe.............................. 14 752 55 287 46 832 12.6 47.3 40.1 106.7 105.1 79.4 Western Europe............................... 23 939 86 147 60 829 14.0 50.4 35.6 105.5 105.9 81.7

Northern America ................................ 80 230 238 374 119 015 18.3 54.5 27.2 105.1 102.4 81.5

Oceania................................................. 9 144 27 056 10 992 19.4 57.3 23.3 106.0 104.3 84.1 Australia/New Zealand ................... 5 446 16 711 8 785 17.6 54.0 28.4 105.5 102.8 81.9 Melanesia ........................................ 3 256 9 101 1 856 22.9 64.0 13.1 106.8 106.7 94.0 Micronesia....................................... 243 677 160 22.5 62.7 14.8 106.4 106.2 89.6 Polynesia......................................... 200 567 191 20.8 59.2 20.0 105.6 106.5 92.6

Africa ................................................... 559 222 1 236 385 204 776 28.0 61.8 10.2 102.3 102.0 90.7 Eastern Africa ................................. 207 114 427 796 56 206 30.0 61.9 8.1 101.7 101.4 92.0 Middle Africa.................................. 107 374 210 406 22 864 31.5 61.8 6.7 102.2 100.7 91.0 Northern Africa............................... 62 419 180 862 60 274 20.6 59.6 19.9 104.8 103.1 87.7 Southern Africa ............................... 13 535 35 909 7 498 23.8 63.1 13.2 102.8 108.9 84.6 Western Africa ................................ 168 779 381 412 57 934 27.8 62.7 9.5 102.3 102.2 93.4

Asia ...................................................... 1 060 501 3 140 955 1 226 714 19.5 57.9 22.6 105.6 104.9 86.8 Eastern Asia .................................... 268 310 885 727 511 161 16.1 53.2 30.7 107.8 107.9 84.5 South-central Asia........................... 527 299 1 537 836 473 646 20.8 60.6 18.7 105.0 104.3 90.4 South-eastern Asia .......................... 158 815 465 726 175 761 19.8 58.2 22.0 104.7 102.2 83.2 Western Asia................................... 106 077 251 666 66 146 25.0 59.4 15.6 104.7 103.8 88.4

Latin America and the Caribbean ........ 161 328 463 041 181 191 20.0 57.5 22.5 104.5 100.8 79.6 Caribbean ........................................ 9 705 28 241 11 870 19.5 56.7 23.8 104.7 101.1 80.5 Central America.............................. 44 227 127 544 48 458 20.1 57.9 22.0 104.7 100.0 80.9 South America................................. 107 396 307 256 120 863 20.1 57.4 22.6 104.5 101.0 79.1

The group of least developed countries, where

the population will still be fairly young at the end of the projection period, will experience a sharp reduction in the child-adult ratio (from a value of 83 children per 100 adults in 2000 to 48 in 2050) and, despite the increase of the ratio of older per-sons per adult, the least developed countries will have a considerably lower overall dependency

ratio by 2050 than they had in 2000 (63 depend-ants per 100 adults in 2050 as opposed to 92 in 2000). The trends exhibited by the least developed countries as a whole parallel those for Africa and all its regions. By 2050, the proportion of older persons in the regions of sub-Saharan Africa will still be low (ranging from 7 per cent to 13 per cent) and the proportion of children will have de-


TABLE V.25. VARIOUS TYPES OF DEPENDENCY RATIOS, BY MAJOR AREA AND RE GION, MEDIUM VARIANT, 1950, 2000 AND 2050

Overall dependency-ratio (per cent)

Child/adult ratio (per cent)

Older person/adult ratio (per cent)

Major area or region 1950 2000 2050 1950 2000 2050 1950 2000 2050 World ............................................... 73.7 66.6 72.5 59.6 49.9 36.2 14.2 16.7 36.3

More developed regions................... 64.2 60.6 96.0 44.9 29.4 30.5 19.3 31.2 65.6 Less developed regions .................... 78.7 68.1 69.6 67.2 55.2 36.9 11.5 12.9 32.7

Least developed countries .............. 86.9 92.4 62.9 76.7 83.0 47.5 10.2 9.4 15.4 Less developed regions without the least developed countries ...... 77.7 64.8 71.6 66.0 51.4 33.7 11.7 13.4 37.9

Europe.............................................. 62.0 60.6 102.4 42.4 28.0 28.2 19.6 32.5 74.2 Eastern Europe............................ 60.9 58.0 103.5 45.3 28.6 28.6 15.7 29.4 74.9 Northern Europe.......................... 62.8 64.7 96.5 38.6 31.2 29.9 24.2 33.5 66.6 Southern Europe.......................... 63.7 60.3 111.4 45.3 25.3 26.7 18.5 35.0 84.7 Western Europe........................... 62.1 63.1 98.4 37.8 27.7 27.8 24.3 35.4 70.6

Northern America ............................ 65.6 60.4 83.6 45.1 34.4 33.7 20.5 26.0 49.9

Oceania............................................. 69.2 63.4 74.4 50.3 41.5 33.8 18.9 21.9 40.6 Australia/New Zealand ............... 65.5 59.1 85.2 44.7 33.3 32.6 20.8 25.8 52.6 Melanesia .................................... 85.9 77.9 56.2 75.4 69.9 35.8 10.5 8.0 20.4 Micronesia................................... 67.1 83.5 59.5 61.9 70.9 35.8 5.2 12.6 23.6 Polynesia..................................... 100.1 72.0 69.0 91.8 60.3 35.2 8.3 11.7 33.8

Africa ............................................... 89.5 91.1 61.8 79.5 81.4 45.2 10.0 9.7 16.6 Eastern Africa ............................. 93.2 98.9 61.6 83.9 90.1 48.4 9.3 8.9 13.1 Middle Africa.............................. 88.9 108.5 61.9 77.8 98.3 51.0 11.1 10.1 10.9 Northern Africa........................... 88.1 72.0 67.8 77.6 61.3 34.5 10.5 10.7 33.3 Southern Africa ........................... 81.8 68.5 58.6 71.0 58.9 37.7 10.9 9.6 20.9 Western Africa ............................ 89.3 98.2 59.4 79.5 88.8 44.3 9.7 9.4 15.2

Asia .................................................. 76.2 64.0 72.8 64.3 49.6 33.8 11.9 14.4 39.1 Eastern Asia ................................ 71.1 54.1 88.0 58.4 36.8 30.3 12.7 17.4 57.7 South-central Asia....................... 80.9 73.0 65.1 69.8 60.8 34.3 11.1 12.2 30.8 South-eastern Asia ...................... 81.5 65.4 71.8 70.6 53.6 34.1 10.9 11.8 37.7 Western Asia............................... 84.0 75.4 68.4 70.9 63.0 42.1 13.1 12.5 26.3

Latin America and the Caribbean .... 85.0 65.2 74.0 74.0 52.1 34.8 11.0 13.1 39.1 Caribbean .................................... 83.0 65.0 76.4 70.4 48.7 34.4 12.6 16.3 42.0 Central America.......................... 95.5 71.0 72.7 82.9 59.6 34.7 12.7 11.4 38.0 South America............................. 82.1 63.1 74.3 71.8 49.7 35.0 10.2 13.4 39.3

clined to nearly 59 per cent of the level in 2000, so that the overall dependency ratio will also be significantly lower than in 2000. The largest re-ductions of the dependency ratio are expected in Eastern Africa, Middle Africa and Western Af-rica, regions where the transition to low fertility is least advanced.

In the process of transition from high mortality and fertility to low levels of both, the period dur-ing which the proportion of children declines in favour of the rising proportion of adults but with-out a sharp increase in the proportion of older per-sons is considered a window of opportunity. It is a time when the countries concerned can take ad-


vantage of the opening provided by declining de-pendency ratios, to readjust their social and eco-nomic institutions in order to be better prepared to satisfy the needs of the ageing population that will follow. Clearly, this period of opportunity is still ahead for the least developed countries, especially those in Africa. It should be noted, however, that even though in terms of proportions and depend-ency ratios future prospects appear rosy, the in-creases in terms of numbers of persons are large. Thus, the older population of Africa is expected to rise from 40 million in 2000 to 205 million in 2050, a five-fold increase, and the adult popula-tion will grow from 415 million to 1.2 billion. Providing gainful employment to such a rapidly growing population is a crit ical goal for Govern-ments over the coming years.

Among the other regions of the less developed

world, declines in the overall dependency ratio are expected in Melanesia, Micronesia and Polynesia but in no case are they so marked as in most of the regions of sub-Saharan Africa. South-central Asia and Western Asia also register moderate reduc-tions of the dependency ratio. In all these regions, the ratio of older persons to adults rises signif i-cantly, reaching levels between 20 and 34 older persons per 100 adults in 2050, but the proportion of the population aged 60 years or over remains moderate (in the range of 13 to 20 per cent). Nev-ertheless, by 2050 South-central Asia alone will have nearly half a billion elderly persons (473 million).

In Latin America and the Caribbean, Central

America is expected to experience almost no change in the dependency ratio between 2000 and 2050, but the other regions will experience mod-erate increases. South-eastern Asia and Eastern Asia display patterns of increase similar to those of the Caribbean and South America. By 2050, the Caribbean, South America and South-eastern Asia all have dependency ratios of about 72 to 76 de-pendants per 100 adults, higher than in the less developed regions as a whole but considerably lower than in the more developed regions. Only Eastern Asia, with a ratio of 88 dependants per 100 adults, has a level even higher than those of Australia/New Zealand and Northern America.

The highest overall dependency ratios are those expected for the regions of Europe, which vary between 97 dependants per 100 adults for North-ern Europe and 111 dependants per 100 adults for Southern Europe. In all the regions of Europe the ratio of older persons to adults is 67 or higher (85 in the case of Southern Europe), whereas the ratios of children to adults are expected to be the lowest in the world (see table V.25). By 2050, Europe as a whole is expected to have 221 million persons over the age of 60, 298 million adults and just 84 million children. Clearly, as figure V.9 shows, by 2050 Europe is the region that comes closest to having an age distribution resembling an inverted pyramid.

However, within Europe, contrasting patterns of

age distribution can be observed between Eastern European countries, in particular those with economies in transition, and the rest of Europe. Thus, in 2000, while the age pyramid of Eastern European countries showed a deficit of males and females in the age group 55-59 years as a result of lower fertility during the Second World War, the rest of the European countries, mainly those that are members of the European Union, displayed a more regular distribution by age and sex, charac-teristic of low-fertility countries, with a narrow base and a bulge in the adult ages. By 2050, the impact of the second World War on the age and sex distribution of Eastern European countries will have disappeared, but among the elderly, the surplus of women is expected to be more pro-nounced in Eastern Europe that in the rest of Europe.

Another aspect that deserves attention is the im-

balances in the distribution by sex that character-ize the older age groups of countries with ageing populations. As tables V.23 and V.24 show, whereas at younger ages (0-14) males tend to out-number females and over the adult age range both tend to be almost equally numerous, females clearly predominate at older ages. At the world level and for the more developed regions, the number of males per female at ages 60 or over is expected to rise between 2000 and 2050, but a slight reduction is noticeable among the less de-veloped regions. In spite of those changes, the

Figure V.9. Age composition of the populations of Europe, Eastern Europe and the European Union, 2000 and 2050 (medium variant)

Europe, 2000

4 0 3 0 2 0 1 0 0 1 0 2 0 3 0 4 0

0 - 4

1 0 - 1 4

2 0 - 2 4

3 0 - 3 4

4 0 - 4 4

5 0 - 5 4

6 0 - 6 4

7 0 - 7 4

8 0 - 8 4

9 0 - 9 4

1 0 0 +

Thousands

Males Females

Eastern Europe, 2000

2 0 1 5 1 0 5 0 5 1 0 1 5 2 0

0 - 4

1 0 - 1 4

2 0 - 2 4

3 0 - 3 4

4 0 - 4 4

5 0 - 5 4

6 0 - 6 4

7 0 - 7 4

8 0 - 8 4

9 0 - 9 4

1 0 0 +

Thousands

Males Females

European Union, 2000

2 0 1 5 1 0 5 0 5 1 0 1 5 2 0

0 - 4

1 0 - 1 4

2 0 - 2 4

3 0 - 3 4

4 0 - 4 4

5 0 - 5 4

6 0 - 6 4

7 0 - 7 4

8 0 - 8 4

9 0 - 9 4

1 0 0 +

Thousands

Males Females

Europe, 2050

4 0 3 0 2 0 1 0 0 1 0 2 0 3 0 4 0

0 - 4

1 0 - 1 4

2 0 - 2 4

3 0 - 3 4

4 0 - 4 4

5 0 - 5 4

6 0 - 6 4

7 0 - 7 4

8 0 - 8 4

9 0 - 9 4

1 0 0 +

Thousands

Males Females

Eastern Europe, 2050

2 0 1 5 1 0 5 0 5 1 0 1 5 2 0

0 - 4

1 0 - 1 4

2 0 - 2 4

3 0 - 3 4

4 0 - 4 4

5 0 - 5 4

6 0 - 6 4

7 0 - 7 4

8 0 - 8 4

9 0 - 9 4

1 0 0 +

Thousands

Males Females

European Union, 2050

2 0 1 5 1 0 5 0 5 1 0 1 5 2 0

0 - 4

1 0 - 1 4

2 0 - 2 4

3 0 - 3 4

4 0 - 4 4

5 0 - 5 4

6 0 - 6 4

7 0 - 7 4

8 0 - 8 4

9 0 - 9 4

1 0 0 +

Thousands

Males Females


fact remains that women have higher probabilities of surviving to old age than men, tending to out-number men by important margins as age in-creases.

H. THE OLDEST OLD According to the dynamics of population age-

ing, as the process gains momentum, the older a group, the faster it grows. Sexagenarians, for in-stance, increased by 159 per cent between 1950 and 2000, while the group of those aged 70-79 years increased by 225 per cent. Still more rapid increases occurred for the group of the “oldest old”, that is, those aged 80 years or over. Between 1950 and 2000, the number of persons in this group more than trebled.

In 2000, 69 million persons in the world were

aged 80 years or over, representing just 1.1 per cent of the world population. They tended to be concentrated in a few large countries. China had the highest number: 11.5 million people, constitut-ing 17 per cent of all people aged 80 years or over in the world. Other countries with high numbers of persons aged 80 years or over included: the United States (9.2 million), India (6.1 million), Japan (4.8 million), Germany (3.0 million) and the Russian Federation (2.9 million). Together, these countries accounted for 54 per cent of the oldest-old globally. In 2000, the three countries with the highest proportions of oldest-old persons in their populations were Sweden (5.1 per cent), Norway (4.5 per cent) and the United Kingdom (4.1 per cent).

Owing to its high rates of growth, the popula-

tion aged 80 years or over will increase dramati-cally. By 2050, the group of the oldest old is ex-pected to be more than 5 times larger than today. The number of octogenarians (persons aged 80-89) in the world is projected to increase to 314 million in 2050, a figure 5.1 times the equiva-lent for 2000. The number of nonagenarians (those aged 90-99) will increase nearly eight-fold, to reach 61 million. The number of people aged 100 years or more will grow the fastest. By 2050, the number of centenarians is projected to be six-teen times as large as in 2000, reaching 3.2 mil-lion.

In 2050, 19 countries or areas are projected to have proportions of persons aged 80 years or over of 10 per cent or higher. They are, in order of the proportion of oldest old that they will have: Japan, Austria, Italy, Switzerland, Spain, Germany, Sin-gapore, Sweden, the Channels Islands, Macao SAR, Greece, Slovenia, Belgium, Hong Kong SAR, the United Kingdom, Finland, France, Nor-way and the Netherlands. In addition, six coun-tries will have at least 10 million persons aged 80 years or over: China (99 million), India (48 million), the United States of America (30 million), Japan (17 million), Brazil (10 mil-lion) and Indonesia (10 million). Together they will account for 57 per cent of all the oldest old in the world.

Mortality risks are very high at older ages, so that the age distribution above age 80 narrows very fast. Octogenarians outnumber nonagenari-ans by a wide margin, and the proportion of cen-tenarians among the oldest old is very small. It is estimated that, at the global level, about 88 per cent of the oldest old (61 million) were octoge-narians and about 12 per cent (8 million) were nonagenarians in 2000. The proportion of cente-narians among the oldest old was extremely small, amounting to just 0.3 per cent (0.2 mil-lion). By 2050, the distribution will become slightly less concentrated in the age group 80-89, since by then they will account for 83 per cent of all persons aged 80 years or over (see table V.26).

As with the older population in general, the old-est old include a majority of women. As figure V.10 shows, women outnumber men at older ages but especially in the more advanced ages. The ratio of the number of women to men increases sharply as the age groups become older. Among octogenarians there were nearly 1.8 women per man in 2000, but by 2050 the ratio is expected to decline to about 1.5 women per man. A small de-crease is also expected in the female to male ratio for age group 90-99, from almost 3 women per man in 2000 to 2.5 women per man by 2050. Among centenarians, however, the female to male ratio is expected to increase markedly, so that by 2050 this age group will have more than 6 women per man.


TABLE V.26. AGE DISTRIBUTION OF THE OLDEST OLD FOR THE WORLD, MEDIUM VARIANT, 2000 AND 2050

Group Age group 2000 2050

Population (millions) Oldest old................. 80+ 69.2 379.0 Octogenarian ............ 80-89 61.1 314.4 Nonagenarian ........... 90-99 8.0 61.4 Centenarian .............. 100+ 0.2 3.2

Percentage Oldest old................. 80+ 100.0 100.0 Octogenarian ............ 80-89 88.2 83.0 Nonagenarian ........... 90-99 11.5 16.2 Centenarian .............. 100+ 0.3 0.8

People surviving past their one-hundredth birth-day have always attracted much attention; becom-ing a centenarian is still an exceptional event. Al-though the proportion of people who survive past the age of 100 is still very small, the number of

people involved is far from negligible (see table V.27). There were approximately 180,000 cente-narians in the world in 2000 and by 2050 this group will number 3.2 million, with one centenar-ian for every 2,917 people. Japan is projected to have the highest proportion of centenarians in 2050, at 8.8 per 1,000 persons. Japan’s centenar-ian population will consist of 959,000 persons, 87,000 males and 872,000 females. Very high proportions of centenarians are also projected for Finland, Italy, Norway, Singapore, Switzerland and Sweden, at slightly below 2 per thousand in each country.

While the highest proportions of centenarians

are found among countries from more developed regions, large centenarian populations are also projected in very large countries located in the less developed regions. China, owing to its large population and low mortality, is projected to have the third largest centenarian population in the

Figure V.10. Females per 100 males for selected age groups above age 60, 2000 and 2050

109131

178

290

499

103 118151

250

615

0

100

200

300

400

500

600

700

60-69 70-79 80-89 90-99 100+

Age groups

Fem

ales p

er 10

0 male

s

2000 2050


TABLE V.27. COUNTRIES WITH 10,000 OR MORE CENTENARIANS IN 2050, MEDIUM VARIANT

Country or area Centenarians (thousands)

Population (thousands)

Population per centenarian

Japan............................................... 959 109 220 114United States of America ............... 473 397 063 839China .............................................. 471 1 462 058 3 106India ............................................... 142 1 572 055 11 103France............................................. 119 61 832 517Germany......................................... 115 70 805 617United Kingdom............................. 95 58 933 618Italy ................................................ 70 42 962 614Brazil.............................................. 56 247 244 4 389Russian Federation......................... 51 104 258 2 053Canada............................................ 45 40 407 904Spain............................................... 34 31 282 929Republic of Korea .......................... 30 51 560 1 696Mexico ........................................... 30 146 651 4 940Australia......................................... 29 26 502 919Colombia ........................................ 23 70 862 3 079Poland............................................. 21 33 370 1 582Sweden ........................................... 19 7 777 413Thailand ......................................... 19 82 491 4 443Belgium .......................................... 17 9 583 565Netherlands .................................... 17 15 845 947China, Hong Kong SAR................. 14 9 648 683Indonesia ........................................ 13 311 335 23 286Greece ............................................ 13 8 983 675Pakistan.......................................... 12 344 170 27 727Turkey............................................ 12 98 818 8 314Argentina........................................ 12 54 522 4 607Austria............................................ 12 6 452 559Switzerland..................................... 11 5 607 500

world in 2050, with close to half a million people, or one centenarian per 3,106 people. The largest centenarian population will be in Japan, followed by that in the United States of America. India will come in fourth place, following China (see table V.27).

_________________

REFERENCE

Durand, J. D. (1977). Historical estimates of world population: An evaluation. Population and Development Review (New York), vol. 3, No. 3.

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