Research Note 9 1999-2000

World Population Projections

Gerard Newman
Statistics Group
19 October 1999

Introduction

On 12 October United Nations Secretary-General Mr Kofi Annan announced that the world's population had reached 6 billion. The birth of a baby boy in a Sarajevo hospital was chosen to symbolically represent the milestone. The United Nations estimates that the population of the world has doubled in the last 28 years. However, recent UN population projections estimate that the rate of increase in world population has slowed and that by the UN's low projection the world population will peak at 7.5 billion by 2040 and then decline.

This Research Note provides a summary of the latest UN population projections (1998 Revision) and compares the 1998 projections with previous projections.

World Population Milestones

UN Projections

Since the 1950s the Population Division of the Department of Economic and Social Affairs of the United Nations Secretariat has produced reports on world demographic estimates and population projections. The latest report - The 1998 Revision -represents the sixteenth round of population projections by the UN.

The 1998 report shows population projections to the year 2050 for individual countries, country groupings and the world for three different growth scenarios: low, medium and high. The three scenarios, or variants in UN terms, are based on past trends and possible future developments regarding fertility, mortality and migration. While assumptions on trends in mortality and migration do not change between the three variants, different fertility assumptions apply. The high and low variants are usually thought to bracket the probable upper and lower range of future population growth for each country while the medium variant is the middle of the fertility assumptions. The UN states that a comparison of observed population change with past projections shows that the medium variant best describes future world population growth. For this reason the medium variant has been used in this paper, although both the high and low variants are shown for comparison purposes.

1998 Projections

The 1998 population projections show that by 2050 the world population will be in the range of 7.3 billion to 10.7 billion, with a medium estimate of 8.9 billion. The low variant projection shows that the world population will peak at 7.5 billion in 2040 and then begin to fall. Both the high and medium variants show the world population continuing to increase throughout the period but at a slower rate. By 2050 annual population growth rates are expected to vary from a low of -0.17 per cent to a high of 0.89 per cent (medium 0.38 per cent), compared with 1.46 per cent at present. Fertility¹ is expected to decline under all three variants with the low and medium variants showing fertility below replacement level by 2010 for the low variant and by 2040 for the medium variant. Given a fertility rate below replacement level for the medium variant, this variant will also show a population decline after around 2070. By 2000 the number of countries with a fertility rate at or below the replacement level is estimated to be 61, an increase of 10 over the number in 1995. The combined population of these 61 countries is 2.6 billion in 1998, 44 per cent of the world population.

1998 UN Population Projections
million

Year	Low	Medium	High
2000	6027.5	6055.1	6082.2
2005	6342.6	6429.4	6516.5
2010	6620.6	6794.8	6966.3
2015	6871.9	7154.4	7430.5
2020	7095.4	7501.5	7903.8
2025	7275.1	7823.7	8379.1
2030	7397.3	8112.0	8849.6
2035	7460.4	8362.9	9313.4
2040	7467.6	8576.5	9768.9
2045	7427.1	8757.7	10221.0
2050	7343.2	8909.1	10673.7

According to the medium variant, population increase over the period to 2050 will occur in the less developed world. The population of the more developed world will be less in 2050 (1155m) than in 1995 (1172m). However, in the less developed world the population is expected to increase by over 70 per cent from 4495m in 1995 to 7754m in 2050. The percentage of the world's population in the less developed world is expected to increase from 79.3 per cent in 1995 to 87.0 per cent in 2050.²

Again according to the medium variant, the number of countries with a population of over 100 million will increase from ten in 1998 to 18 in 2050, only three of which (United States, Russia and Japan) are located in the more developed world. India will replace China as the most populous country with a population of 1529m by 2050.

Population Over 100 Million, 2050
Medium Variant
million

	Population
India	1 529
China	1 478
United States	349
Pakistan	346
Indonesia	312
Nigeria	244
Brazil	244
Bangladesh	213
Ethiopia	170
Congo DR	160
Mexico	147
Philippines	131
Viet Nam	127
Russia	122
Iran	115
Egypt	115
Japan	105
Turkey	101

Previous Projections

A notable feature of recent UN population projections is that the projections have been revised downwards. It would appear that the decline in world population growth has taken even the UN demographers by surprise, with each revision showing a lower world population than the previous set of projections. Between the 1990 and 1998 Revisions the projected population for 2025 has been revised downwards by 680m, or by 8 per cent. A more dramatic revision has occurred between the 1994 Revision and the 1998 Revision. In 1994 the UN estimated world population in 2050 to be 9833m; this figure was revised downwards by 924m (9.4 per cent) in the 1998 projections.

Previous UN Population Projections
million

Projection (a)	2025	2050
1990 Revision	8504	n.a.
1992 Revision	8472	n.a.
1994 Revision	n.a.	9833
1996 Revision	8039	9367
1998 Revision	7824	8909
(a) Medium variant.

AIDS Impact

The decline in world population growth, however, is not all good news, as about one third of the reduction in long-range population projections is due to increased mortality rates in sub-Sahara Africa and parts of the Indian subcontinent, resulting from the AIDS epidemic.

The impact of AIDS on mortality and population loss can be clearly seen in the 29 African countries with the highest incidence of HIV/AIDS. In these countries life expectancy at birth is forecast to be 9 years lower (from 58.4 years to 49.4 years) by 2005-2010 than it would have been without AIDS. In the two countries hardest hit, Botswana and Zimbabwe, the population is forecast to be some 20 per cent lower by 2015 than it would have been without AIDS. In spite of the AIDS epidemic the population of sub-Sahara Africa is still expected to increase by nearly 140 per cent from 2000 to 2050 due to high fertility rates.

References:

World Population Prospects: The 1998 Revision, United Nations, 1999.

The State of the World Population 1999:6 Billion, United Nations Population Fund.

United Nations Internet site: www.popin.org/pop1998/

1. Fertility is measured by the total fertility rate, which represents the number of children one woman would bear during her child-bearing lifetime. In the long term, a fertility rate of around 2.1 leads to a population with a constant size.
2. The division of countries into more or less developed is a present day classification. Over time some countries may change from being less developed to more developed and this may effect the proportion of the world's population in each category.

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