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The 2006 Revision is the
twentieth round of official United Nations population estimates and projections
prepared by the Population Division of the Department of Economic and Social
Affairs of the United Nations Secretariat. These are used throughout the United
Nations system as the basis for activities requiring population information.
The 2006 Revision builds on the 2004 Revision and incorporates both the results
of the 2000 round of national population censuses and of recent specialized
surveys carried around the world. These sources provide both demographic and
other information to assess the progress made in achieving the internationally
agreed development goals, including the Millennium Development Goals (MDGs).
The comprehensive review
of past worldwide demographic trends and future prospects presented in the 2006
Revision provides the population basis for the assessment of those goals.
According to the 2006 Revision,
the world population will likely increase by 2.5 billion over the next 43 years,
passing from the current 6.7 billion to 9.2 billion in 2050. This increase is
equivalent to the size the world population had in 1950 and it will be absorbed
mostly by the less developed regions, whose population is projected to rise
from 5.4 billion in 2007 to 7.9 billion in 2050. In contrast, the population
of the more developed regions is expected to remain largely unchanged at 1.2
billion and would have declined were it not for the projected net migration
from developing to developed countries, which is expected to average 2.3 million
persons annually.
As a result of declining
fertility and increasing longevity, the populations of a growing number of countries
are ageing rapidly. Between 2005 and 2050, half of the increase in the world
population will be accounted for by a rise in the population aged 60 years or
over, whereas the number of children (persons under age 15) will decline slightly.
Furthermore, in the more developed regions, the population aged 60 or over is
expected to nearly double (from 245 million in 2005 to 406 million in 2050)
whereas that of persons under age 60 will likely decline (from 971 million in
2005 to 839 million in 2050).
The 2006 Revision confirms
the diversity of demographic dynamics among the different world regions. While
the population at the global level is on track to surpass 9 billion by 2050
and hence continues to increase, that of the more developed regions is hardly
changing and will age very markedly. As noted, virtually all population growth
is occurring in the less developed regions and especially in the group of the
50 least developed countries, many of which still have relatively youthful populations
which are expected to age only moderately over the foreseeable future. Among
the rest of the developing countries, rapid population ageing is forecast.
Underlying these varied
patterns of growth and changes in the age structure are distinct trends in fertility
and mortality. Below-replacement fertility prevails in the more developed regions
and is expected to continue to 2050. Fertility is still high in most of the
least developed countries and, although it is expected to decline, it will remain
higher than in the rest of the world. In the rest of the developing countries,
fertility has declined markedly since the late 1960s and is expected to reach
below-replacement levels by 2050 in the majority of them.
Mortality in the established
market economies of the developed world is low and continues to decline, but
it has been stagnant or even increasing in a number of countries with economies
in transition, largely as a result of deteriorating social and economic conditions
and, in some cases, because of the spread of HIV. Mortality is also decreasing
in the majority of developing countries, but in those highly affected by the
HIV/AIDS epidemic, mortality has been increasing.
The HIV/AIDS epidemic continues
to spread. The number of countries with a significant number of infected people
in the 2006 Revision is 62, up from 60 in the 2004 Revision and 53 in the 2002
Revision. Although HIV prevalence in some countries has been revised downward
on the basis of newly available nationally representative data, the toll of
the disease continues to be high and is expected to remain so, despite projected
reductions in the prevalence of HIV/AIDS.
Lower projected levels
of HIV prevalence depend on the realization of the commitments made by Governments
in the 2000 Millennium Declaration4 and the 2001 United Nations Declaration
of Commitment on HIV/AIDS5. In particular, the projected population trends depend
on achieving a major increase in the proportion of AIDS patients who get antiretroviral
therapy to treat the disease and on the success of efforts to control the further
spread of HIV. In the 2006 Revision, the 62 countries considered to be highly
affected by the HIV/AIDS epidemic include 40 located in Africa. In projecting
the effect of the disease, it is assumed that 31 of the most affected countries
will manage to provide by 2015 antiretroviral treatment to 70 per cent or more
of the persons suffering from AIDS. In the rest of the affected countries, treatment
levels are expected to be lower, reaching between 40 per cent and 50 per cent
by 2015. It is further assumed that persons receiving treatment survive, on
average, 17.5 years instead of the 10 years expected in the absence of treatment.
Mainly as a result of these assumptions and owing to the downward revision of
the prevalence of HIV/AIDS in countries where nationally representative data
on the epidemic have become available, an estimated 32 million fewer deaths
are projected to occur during 2005-2020 in the 62 countries most affected by
the epidemic according to the 2006 Revision than would have occurred if death
rates were the same as in the 2004 Revision. These changes also contribute to
make the population projected to 2050 in the 2006 Revision larger than that
in the 2004 Revision (9.2 billion vs. 9.1 billion).
Realization of the medium
variant projections contained in the 2006 Revision is also contingent on ensuring
that fertility continues to decline in developing countries. According to the
2006 Revision, fertility in the less developed countries as a whole is expected
to drop from 2.75 children per woman in 2005-2010 to 2.05 in 2045-2050. The
reduction expected in the group of
50 least developed countries is even sharper: from 4.63 children per woman to
2.50 children per woman. To achieve such reductions it is essential that access
to family planning expands in the poorest countries of the world. The urgency
of realizing the reductions of fertility projected is brought into focus by
considering that, if fertility were to remain constant at the levels estimated
for 2000-2005, the population of the less developed regions would increase to
10.6 billion instead of the 7.9 billion projected by assuming that fertility
declines. That is, without further reductions of fertility, the world population
could increase by twice as many people as those alive in 1950.
Other key findings
resulting from the comprehensive review of past worldwide demographic trends
and future prospects presented in the 2006 Revision are summarized below.
1. In July 2007 the world
population will reach 6.7 billion, 547 million more than in 2000 or a gain of
78 million persons annually. Assuming that fertility levels continue to decline,
the world population is expected to reach 9.2 billion in 2050 and to be increasing
by about 30 million persons annually at that time, according to the medium variant.
2. Future population growth
is highly dependent on the path that future fertility takes. In the medium variant,
fertility of the world declines from 2.55 children per woman today to slightly
over 2 children per woman in 2050. If fertility were to remain about half a
child above the levels projected in the medium variant, world population would
reach 10.8 billion by 2050. A fertility path half a child below the medium variant
would lead to a population of 7.8 billion by mid-century. That is, at the world
level, continued population growth until 2050 is inevitable even if the decline
of fertility accelerates.
3. Because of its low and
declining rate of population growth, the population of developed countries as
a whole is expected to remain virtually unchanged between 2007 and 2050, at
about 1.2 billion, according to the medium variant. In contrast, the population
of the 50 least developed countries will likely more than double, passing from
0.8 billion in 2007 to 1.7 billion in 2050. Growth in the rest of the developing
world is also projected to be robust, though less rapid, with its population
rising from 4.6 billion to 6.2 billion between 2007 and 2050 according to the
medium variant.
4. Slow population growth
brought about by reductions in fertility leads to population ageing, that is,
it produces populations where the proportion of older persons increases while
that of younger persons decreases. In the more developed regions, 20 per cent
of population is already aged 60 years or over and that proportion is projected
to reach 33 per cent in 2050. In developed countries as a whole, the number
of older persons has already surpassed the number of children (persons under
age 15) and by 2050 there will be more than twice as many older persons in developed
countries than children.
5. Population ageing is
less advanced in developing countries. Nevertheless, the populations of a majority
of them are posed to enter a period of rapid population ageing. In developing
countries as a whole, just 8 per cent of the population is today aged 60 years
or over but by 2050, 20 per cent of their population is expected to be in that
age range.
6. Globally, the number
of persons aged 60 years or over is expected to almost triple, increasing from
673 million in 2005 to 2 billion by 2050. Over the same period, the share of
older persons living in developing countries is expected to rise from 64 per
cent to nearly 80 per cent in 2050.
7. A feature of ageing
populations is that the numbers of persons with older ages grow faster the higher
the age range considered. Thus, whereas the number of persons aged 60 or over
is expected to triple, that of persons aged 80 or over (the oldest-old) is projected
to increase nearly five-fold, from 88 million in 2005 to 402 million in 2050.
Today, about half of the oldest-old live in developing countries but that share
is expected to reach 71 per cent in 2050.
8. Although the population
of all countries is expected to age over the foreseeable future, the population
will remain relatively young in countries where fertility is still high, many
of which are experiencing very rapid population growth. High population growth
rates prevail in a number of developing countries, the majority of which are
least developed. Between 2005 and 2050, the populations of Afghanistan, Burundi,
the Democratic Republic of the Congo, Guinea-Bissau, Liberia, Niger, Timor-Leste
and Uganda are projected to at least triple.
9. In sharp contrast, the
populations of 46 countries or areas, including Germany, Italy, Japan, the Republic
of Korea, most of the successor States of the former USSR and several small
island States are expected to be lower in 2050 than in 2005.
10. Population growth remains
concentrated in the populous countries. During 2005-2050, eight countries are
expected to account for half of the world’s projected population increase:
India, Nigeria, Pakistan, the Democratic Republic of the Congo, Ethiopia, the
United States of America, Bangladesh and China, listed according to the size
of their contribution to globalpopulation growth.
11. The median age, that
is, the age that divides the population in two halves of equal size, can be
used as an indicator of population ageing. At the world level, the median age
is projected to increase from 28 to 38 years between 2005 and 2050. Europe has
today the oldest population, with a median age of nearly 39 years, which is
expected to reach 47 years in 2050.
12. The median age is higher
in countries that have been experiencing low fertility for a long time. In 2005,
13 developed countries or areas had a median age higher than 40 years. The expected
pervasiveness of population ageing is reflected by the fact that in 2050, 93
countries are projected to have median ages above 40 years, 48 of which are
developing countries.
13. Countries where fertility
remains high and has declined only moderately will experience the slowest population
ageing. By 2050, about one in five countries is projected to have a median age
less than 30 years. The youngest populations will be found among the least developed
countries, eight of which are projected to have median ages below 24 years in
2050: Afghanistan, Angola, Burundi, the Democratic Republic of the Congo, Guinea-
Bissau, Liberia, Niger and Uganda (in alphabetical order).
14. As noted above, fertility
reductions are the main cause of population ageing. At the world level, fertility
is estimated to be 2.55 children per woman, about half the level it had in 1950-1955
(5 children per women). In the medium variant, global fertility is projected
to decline further to 2.02 children per woman. Average world levels result from
quite different trends by major development group. In developed countries as
a whole, fertility is currently 1.60 children per woman and is projected to
increase slowly to 1.79 children per woman in 2045-2050. In the least developed
countries, fertility is 4.63 children per woman and is expected to drop by about
half, to 2.50 children per woman by 2045-2050.
In the rest of the developing
world, fertility is already moderately low at 2.45 children per woman and is
expected to decline further to 1.91 children per woman by mid-century, thus
nearly converging to the fertility levels by then typical of the developed world.
15. In 2005-2010, fertility
remains above 5 children per woman in 27 of the 150 developing countries, and
those 27 countries account for 9 per cent of the world population. Most countries
with very high fertility are poor and belong to the group of least developed
countries. In contrast, fertility has reached below-replacement levels in 28
developing countries, which account for 25 per cent of the world population.
This group includes China whose average fertility during 2005-2010 is estimated
at 1.73 children per woman.
16. Fertility is also below-replacement
level in all 45 developed countries or areas, which account for 19 per cent
of the world population. In 27 of them, including Japan and most of the countries
located in Southern and Eastern Europe, fertility remains below 1.5 children
per woman. Since 1990-1995, fertility decline has been the rule among the vast
majority of developed countries and has resulted in rapid population ageing.
17. Another factor contributing
to population ageing is the reduction of mortality at adult ages. Global life
expectancy at birth, which is estimated to have risen from 58 years in 1970-1975
to 67 years in 2005-2010, is expected to keep on rising to reach 75 years in
2045-2050. In the more developed regions, the projected increase is from 77
years today to 82 years by mid-century, and in the less developed regions life
expectancy is projected to rise from 65 years in 2005-2010 to 74 years in 2045-2050.
18. Life expectancy remains
low in the least developed countries, at just 55 years, and although it is projected
to reach 67 years in 2045-2050, realizing such increase is contingent on reducing
the spread of HIV and combating successfully other infectious diseases. Similar
challenges must be confronted if the projected increase of life expectancy in
the rest of the developing countries, from under 68 years today to 76 years
by mid-century, is to be achieved.
19. Among the more developed
regions, Eastern Europe has the lowest life expectancy and it has experienced
reductions in life expectancy at birth since the late 1980s. In 2005-2010 life
expectancy in the region, at 68.6 year, is lower than it was in 1960-1965 (69.3
years). The Russian Federation and Ukraine have experienced serious increases
in mortality, partly because of the spread of HIV.
20. Despite the advances
made in treating people infected with HIV and trying to control the expansion
of the epidemic, its impact in terms of morbidity, mortality and slower x World
Population Prospects: The 2006 Revision population growth continues to be evident
in many countries. In Southern Africa, the region with the highest prevalence
of the disease, life expectancy has fallen from 62 years in 1990-1995 to 49
years in 2005-2010 and is not expected to regain the level it had in the early
1990s before 2045. As a consequence, the growth rate of the population in the
region has plummeted, passing from 2.5 per cent annually in 1990-1995 to 0.6
per cent annually in 2005-2010 and is expected to continue declining for the
foreseeable future.
21. As noted above, the
contribution of international migration to population growth in the more developed
regions has increased in significance as fertility declines. During 2005- 2050,
the net number of international migrants to more developed regions is projected
to be 103 million which counterbalances the excess of deaths over births (74
million) projected over the period.
22. In 2005-2010, net migration
in eight countries or areas more than doubled the contribution of natural increase
(births minus deaths) to population growth: Belgium, Canada, Hong Kong (China
SAR), Luxembourg, Singapore, Spain, Sweden and
Switzerland. In addition, in a further eight countries or areas, net migration
counterbalanced the excess of deaths over births. These countries are: Austria,
Bosnia and Herzegovina, the Channel Islands, Greece, Italy, Portugal, Slovakia
and Slovenia.
23. In terms of annual
averages, the major net receivers of international migrants are projected to
be the United States (1.1 million annually), Canada (200,000), Germany (150,000),
Italy (139,000), the United Kingdom (130,000), Spain (123,000) and Australia
(100,000). The countries with the highest levels of net emigration are projected
to be: China (-329,000 annually) Mexico (-306,000), India (-241,000), Philippines
(-180,000), Pakistan (-167,000) and Indonesia (-164,000).
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