From the dawn of mankind to the turn of the nineteenth century world population grew to a total of one billion people. During the 1800s, human numbers increased at increasingly higher rates, reaching a total of about 1.7 billion people by 1900. World population has grown even more rapidly during the present century, with the greatest gains occurring in the post-World War II period, and stands at over three times its size in 1900 -- some 5.9 billion people -- today.
Population growth has continued throughout the past three decades in spite of the decline in fertility rates that began
in many developing countries in the late 1970s and, in some countries, in spite of the toll taken by the HIV/AIDS
pandemic. While the rate of increase is slowing, in absolute terms world population growth continues to be
substantial. Global population increase is currently equivalent to adding a new Israel, Egypt, Jordan, West Bank,
and Gaza to the existing world total each year.
According to Census Bureau projections, world population will
increase to a level of nearly 8 billion persons by the end of the next quarter century, and will reach 9.3 billion
persons -- a number more than half again as large as today's total -- by 2050.
According to Census Bureau projections, world population will increase to a level of nearly 8 billion persons by the end of the next quarter century, and will reach 9.3 billion persons -- a number more than half again as large as today's total -- by 2050.
The Role of the World's Less Affluent Nations
The future of human population growth has been determined, and is now largely being decided, in the world's less developed nations (LDCs). Ninety-six percent of world population increase now occurs in the developing regions of Africa, Asia and Latin America, and this percentage will rise over the course of the next quarter century.
Ninety percent of the world's births and 77 percent of its deaths will take place in LDCs in 1998. Ninety-nine percent of global natural increase -- the difference between numbers of births and deaths -- occurs in the developing world.(1)
The Census Bureau's projections indicate that early in the next century, crude death rates will exceed crude birth rates for the world's more developed countries (MDCs), and the difference -- natural increase -- will be negative. At this point, international migration will become the critical variable determining whether the total population of today's MDCs increases or decreases. These projections show negative natural increase offset by net international immigration through 2019 but, if present trends continue, the population of the world's MDCs will slowly begin to decrease from the year 2020 onward.
As the growth rate in the world's more affluent nations becomes negative, all of the net annual gain in global population will, in effect, come from the world's developing countries.
Underlying Changes in Fertility and Mortality
Fertility and mortality continue to decline in most world regions, and both have reached levels unprecedented in human history.
However, substantial gaps exist, and will continue to exist, between the world's more developed and less developed regions in numbers of children born to a woman, on average, and in the risks of dying at every age faced by those children. A baby born in Sub-Saharan Africa is far more likely to die in infancy than a child born in another developing region and has a lower life expectancy than a child born anywhere else. A child born in Latin America or Asia can expect to live between 7 and 13 fewer years on average than one born in one of the world's more affluent regions.
Life expectancies at birth, 1998
Western Europe .................... 78 North America ..................... 76 Latin America and the Caribbean .................... 69 Asia .............................. 65 Sub-Saharan Africa ................ 49
This year, about 7.7 million children worldwide will die before their first birthday. Infant mortality will account for about 14 percent of all deaths in 1998. However, disparities in conditions distinguishing today's less developed and more developed countries are also reflected in the portion of all deaths that occur in infancy. At the extremes, where overall mortality risks are highest, infant deaths will represent 20 to 25 percent of all deaths occurring in Sub-Saharan Africa, the Near East and North Africa. In contrast, infant deaths will be only one percent of all deaths in the more developed countries of North America, Europe, Japan, Australia and New Zealand.
Over the course of the next 25 years, the age structure of world population will continue to shift, with older age groups making up an increasingly larger share of the total. For example, during the 1998-2025 period, the world's elderly population (ages 65 and above) will more than double while the world's youth (population under age 15) will grow by 6 percent, and the number of children under age 5 will increase by less than 5 percent. As a result, world population will become progressively older during the coming decades.
Because of population aging, old-age dependency ratios will rise in every major world region during the next 25 years. And the world community as a whole will face an elderly support burden nearly 50 percent larger in 2025 than in 1998.
Even with the rapid growth of the elderly, however, the bulk of the dependent population worldwide will remain children during the coming quarter century. Nearly 9 in every 10 persons making up the combined dependent age groups in the less developed regions of Africa, Asia and Latin America are under age 15 today. And children will still account for three-fourths of all dependents in these regions in 2025. Only in the United States and other more developed countries will elderly dependents come to outnumber dependents under the age of 15 over the course of the next 25 years.
The net effect of decreasing youth dependency and growing old age dependency will differ in the world's MDCs and LDCs. The total dependency ratio, which compares the size of the combined populations under age 15 and ages 65 and over to the working age population (ages 15 to 64), will decline over the 1998-2025 period in the less developed countries and for the world as a whole, while rising in more developed nations.
As We Approach the End of the Decade . . .
Regional and global population change in the coming years will be determined by the interplay of a number of factors. These include:
• the size of the populations of the world's more affluent and less affluent regions and continuing differences in fertility and mortality exhibited by these populations;
• the uncertain future growth rates of several of the world's largest nations including, in particular, India;
• the extent to which couples will have access to reproductive health services, including family planning services, in those nations where fertility remains relatively high; and
• the course of the HIV/AIDS pandemic.
Fertility remains the driving force behind natural increase in the vast majority of countries that contribute the most to world population growth. A key determinant of current fertility, and of the future path of fertility, in these countries is the extent to which couples use -- or fail to use -- contraception to control the number and spacing of their children. In spite of the rapid growth in the number of women using modern contraception worldwide over the past 20 years, substantial numbers of women who would prefer to control their fertility are not doing so. At present, an estimated 120 million married women in the world's developing regions have "unmet need" for contraceptive services and products.
Current estimates indicate over 40 million people have become infected with HIV since the beginning of the pandemic in the late 1970s, and over 11 million of these people have already died. While the majority of the infections have occurred in Sub-Saharan Africa up to now, the spread of the disease in Asia during the coming years may result in many more infections in that region than in Sub-Saharan Africa.
HIV/AIDS has had, and continues to have, substantial and sometimes dramatic impacts on mortality levels in countries most seriously affected. However, AIDS will not overcome the momentum of population growth at the regional level, even in Sub-Saharan Africa. This will be true particularly if changes in behavior, already observed in some settings, bring about an early curtailment of HIV infections in affected countries.
1. The difference between this percentage and the percentage of global population change cited in the
preceding paragraph (96 percent) is international migration from less developed to more developed countries.
Last Revised: 18 Mar 1999 08:01:22 EST
Source: U.S.Bureau of the Census, World Population Profile: 1998, pp. 1-2.
Last Revised: 18 Mar 1999 08:01:22 EST