Birth rates and death rates are declining around the world. Overall economic development, public health programs, and improvements in food production and distribution, water, and sanitation have led to dramatic declines in death rates. And women now have fewer children than they did in the 1950s. Nevertheless, if death rates are lower than birth rates, populations will still grow. Also, it is possible for absolute numbers of births to increase even when birth rates decline.
This figure illustrates the lag between changes in the rate of growth and the net increase in population per year. Over the period 1985-1995, the population growth rate declined (a reflection of declining fertility), yet millions of people were added to the world’s population (which peaked around 1985, when 87 million people were added each year). From 2000 on, the growth rate will continue to decline. Between 2015 and 2020, we will still be adding 72 million people each year. Why? Because the generation of women now having their children is very large as the result of high fertility in their mothers’ and grandmothers’ generations.
By 2025, over 20 percent of the population in more developed regions will be ages 65 and older. By 2025, one-tenth of the world ’ s population will be over age 65. Asia will see the proportion of its elderly population almost double, from about 6 percent in 2000 to 10 percent in 2025. In absolute terms, this represents a stark increase in just 25 years: from about 216 million to about 480 million older people.
Women worldwide are having fewer children in their lifetimes, from an average of five children born per woman in the 1950s to below three in 2000. All of the most recent projections put forth by the UN assume that levels of childbearing will continue to decline in the next century.
In 2045-2050, infants born around the world can expect to live an average of 75 years — up ten years from today. Africa will experience the largest increase in life expectancy: from 49 years to 65 years. Life expectancy varies widely by region. In more developed countries, life expectancy averages 76 years, compared with only 49 years in Africa.
Sex and age distributions show that less developed countries have significantly younger populations than more developed countries. Almost one-third of the population in less developed countries is under age 15. In contrast, less than one-fifth of the population in more developed countries is under 15. Today there are more than 2 billion young people below age 20 in less developed regions—the age cohort that will soon become the world ’ s newest group of parents. Young age structures in the less developed countries are due mainly to higher levels of childbearing in recent decades.
The number of women of childbearing age more than doubled between 1950 and 1990: from 620 million to over 1.3 billion. Their numbers are expected to reach over 2 billion by the middle of this century, according to the UN ’ s medium projections. The growing population of women in their childbearing years and their male partners will contribute to future world population growth, even if levels of childbearing continue to decline.
The number of women in their childbearing years has increased since the 1950s and is projected to continue to increase to 2050. The number of children per woman has declined since the 1950s and is projected to continue to decline. Even though women have on average fewer children than their mothers, the absolute number of babies being born continues to increase because of the increases in the total number of women of childbearing age.
World and Population Statistics World Population: 6.9 Billion-2011 World Population Information The world’s population is expected to reach 7 billion this year-2011 World Population Clock
World Population Growth Through History A.D. 2000 A.D. 1000 A.D. 1 1000 B.C. 2000 B.C. 3000 B.C. 4000 B.C. 5000 B.C. 6000 B.C. 7000 B.C. 1+ million years 8 7 6 5 2 1 4 3 Old Stone Age New Stone Age Bronze Age Iron Age Middle Ages Modern Age Black Death — The Plague 9 10 11 12 A.D. 3000 A.D. 4000 A.D. 5000 1800 1900 1950 1975 2000 2100 Future Billions Source: Population Reference Bureau; and United Nations, World Population Projections to 2100 (1998).
Trends in Population Growth Worldwide Population Increase and Growth Rate, Five-Year Periods Millions Percent increase per year Source: United Nations, World Population Prospects: The 2004 Revision (medium scenario), 2005.
Age Distribution of the World’s Population Population Structures by Age and Sex, 2005 Millions Less Developed Regions More Developed Regions Male Female Male Female 80+ 75-79 70-74 65-69 60-64 55-59 50-54 45-49 40-44 35-39 30-34 25-29 20-24 15-19 10-14 5-9 0-4 Age Source: United Nations, World Population Prospects: The 2004 Revision , 2005.