WORLD POPULATION WOULD STABILIZE AT NEARLY 11 BILLION BY YEAR 220019980202 NEW YORK, 2 February (Department of Economic and Social Affairs) -- World population could reach 10.8 billion persons by 2150 and would ultimately stabilize at nearly 11 billion persons around 2200, according to the medium fertility scenario of the new long-range projections prepared by the Population Division of the Department of Economic and Social Affairs. Low and high fertility scenarios put a large band around the numbers -- from 3.6 billion persons in 2150 to 27 billion in 2150.
The Population Division prepares biennially the official United Nations population estimates and projections for countries, urban and rural areas and major cities for all countries and areas of the world. The latest Revision, "World Population Prospects: The 1996 Revision", refers to the period 1950-2050. Realization of the full consequences of changes in fertility and mortality on population growth requires a longer time-frame. Therefore, periodically the Population Division prepares population projections for an extended projection horizon.
The seven main conclusions from these long-range population projections are:
-- According to the medium-fertility scenario, which assumes fertility will stabilize at replacement levels of slightly above two children per woman, the world population will grow from 5.7 billion persons in 1995 to 9.4 billion in 2050, 10.4 billion in 2100, and 10.8 billion by 2150, and will stabilize at slightly under 11 billion persons around 2200.
-- Although the high- and low-fertility scenarios differ by just one child per couple, half a child above and half a child below replacement fertility levels, the size of the world population in 2150 would range from 3.6 billion persons to 27.0 billion.
-- If fertility rates were to stay constant at 1990-1995 levels for the next 155 years, the world in 2150 would need to support 296 billion persons.
-- If all couples of the world had begun to bear children at the replacement-fertility level in 1995 (about 2 children per couple), the growth momentum of the current age structure would still result in a 67 per cent increase in the world population, to 9.5 billion by 2150.
-- The future will see a continued geographical shift in the distribution of the world population as the share living in the currently more developed regions will decrease from 19 per cent to 10 per cent between 1995 and 2150.
-- Declining fertility and mortality rates will lead to dramatic population ageing. In the medium-fertility scenario, the share aged 60 years or above will increase from 10 per cent to 31 per cent of the world population between 1995 and 2150.
-- The ultimate world population size of nearly 11 billion persons, according to the medium fertility scenario of these projections, is 0.7 billion persons fewer than previously published by the United Nations in 1992, mainly due to larger-than-expected declines in fertility in many countries.
The medium-fertility scenario, which lies in the centre of the projection scenarios, indicates that the world population will reach 9.4 billion by 2050, 10.4 billion by 2100, and 10.8 billion by 2150 (table 1). The population of the world will ultimately stabilize at just under 11 billion persons around 2200.
Table 1. World population projections based on seven scenarios, 1950-2150 (in billions)
Fertility scenarios Year Medium High High/Medium Low/Medium Low Constant Instant Replacement
1950 2.5 2.5 2.5 2.5 2.5 2.5 2.5 1995 5.7 5.7 5.7 5.7 5.75.7 5.7 2050 9.4 11.2 10.8 8.0 7.714.9 8.4 2100 10.4 17.5 14.6 7.2 5.657.2 9.0 2150 10.8 27.0 18.3 6.4 3.6 296.39.5
Source: Population Division of the Department of Economic and Social Affairs at the United Nations Secretariat, World Population Projections to 2150, (United Nations, New York, 1998).
The fertility gap separating the high- and low-fertility scenarios is about one child. According to the high-fertility scenario, world population will grow to 11.2 billion persons by 2050, 17.5 billion by 2100, and 27 billion by 2150. The low-fertility scenario, sharp contrast and shows a world population increasing to 7.7 billion persons by 2050 but then declining to 5.6 billion in 2100 and eventually falling to 3.6 billion by 2150.
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There are two intermediate scenarios, which assume that fertility rates will converge to 10 per cent above replacement level (in the high/medium-fertility extension) and 10 per cent below replacement level (in the low/medium-fertility extension). According to these two scenarios, the world population in 2150 would reach 18.3 billion and 6.4 billion respectively.
The constant-fertility scenario presents the results of future world population growth if fertility rates were to remain at 1990-1995 levels through the year 2150. The results highlight the unsustainability of the current situation: the world population under the constant-fertility scenario would reach 296 billion by the year 2150.
An additional analytical scenario demonstrates the vital role of age structure in influencing long-term population growth. Even if all couples in the world had begun in 1995 to bear children at the replacement-fertility level (instant replacement fertility scenario, which is roughly two children per couple), the built-in growth momentum of the population age structure will mean that the population of the world would continue to grow to 9.5 billion by the year 2150 -- a 67 per cent increase from 1995.
The growth of the major areas of the world is far from homogenous. According to the results of the medium-fertility scenario, population growth will continue in all major areas except Europe. The population of Africa will nearly quadruple over the 155 year period -- increasing from 0.7 billion persons in 1995 to 2.8 billion in 2150. Growth is also projected for Asia, with China growing from 1.2 billion persons to 1.6 billion, India from 0.9 billion persons to 1.7 billion, and the rest of Asia from 1.3 billion persons to 2.8 billion. The population of Latin America and the Caribbean is projected to rise from 477 million persons in 1995 to 916 million in 2150.
Northern America's population in 1995 is estimated at 297 million persons and it is expected to increase to 414 million by 2150. Oceania is expected to increase from 28 million persons to 51 million. Europe is the only major area whose population is projected to decline over time. In 1995, Europe's population stood at 728 million persons. By 2150, it is projected to fall to 595 million persons -- a decline of 18 per cent over 155 years.
The different growth paths of the major areas of the world will lead to a substantial redistribution of the world population across the globe. The medium-fertility scenario projects a decline in the proportion of the world population living in Europe and Northern America and an increase in the proportion found in Africa and several other parts of the world that are today categorized as less developed regions. In 1950, the population of Europe was more than twice that of Africa. However, by 2150, the population of Europe is projected to be one fifth the size of Africa, according to the medium-fertility scenario.
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The growth in the size of the world population is matched by a large shift in the age structure of the world population. The medium-fertility scenario indicates that the median age of the world population will rise from 25.4 years in 1995, to 36.5 years in 2050, to 42.9 years by 2150. The share of the world's population under 15 years of age will decline from 31 per cent in 1995 to 17 per cent by 2150. In contrast, the percentage of the population of the world aged 60 or above will increase rapidly from 9 per cent in 1995 to 30 per cent in 2150. Among the elderly age groups, it is the oldest old -- those aged 80 or over -- that will increase the most rapidly over time. According to the medium-fertility scenario, the number aged 80 or over will grow from 61 million in 1995 to 320 million in 2050 and 1,055 million by 2150.
The Population Division's study shows that while it is certain that the world population will continue to grow significantly over the next half century, there is less certainty in the longer term. This range of potential demographic outcomes underscores the difficulty in focusing on any particular scenario and also highlights the critical importance of current policies and actions for the long-range future of the world population.
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