Prospects for stabilizing the world's soaring population have taken a blow. This development, if not reversed, will have huge economic, environmental, and political impacts on most people alive today.
Two years ago, the United Nations projected that the number of people on this planet would reach 8.9 billion by 2050. In March, the UN Population Division revised that projection to 9.2 billion.
If UN demographers are right, in 43 years the world's population will increase by 2.5 billion, up from 6.7 billion today. That growth is equivalent to how many people lived on Earth in 1950. The difference in the two UN projections, separated by only two years, is equal to today's population of the United States.
Talk of a "birth dearth" remains true for most industrial countries. The US, with a high rate of immigration, legal and illegal, is an exception.
But the population "explosion" is not over in many developing countries.
"The rate of progress has come down," warns Stanley Bernstein, a senior policy adviser for the United Nations Population Fund (UNFPA). His boss, Thoraya Ahmed Obaid, executive director of UNFPA, points to a steep decline in world foreign aid for family planning, from $723 million in 1955 to $442 million in 2004 (in constant dollars).
"There are 200 million women in the developing world with an unmet need for effective contraception," she said in an address last month. "The result is increasing numbers of unwanted pregnancies, rising rates of unsafe abortion, and increased risks to the lives of women and children."
The UN projects the population of developing countries will rise from 5.4 billion today to 7.9 billion in 2050. In that time, the number of people in the developed world will remain largely unchanged, at 1.2 billion. Populations of Europe, Japan, and Russia will actually decline.
Of course, such projections decades into the future are imprecise. Hania Zlotnik, director of the UN Population Division, after citing her 2050 population projection in a phone interview, added, "give or take 200 million."
The UN projection assumes that women age 15 to 19 in 2005 will have 2.5 children during their lives. That's the average for the world. For Africa, the average is assumed to be 4.1; for Asia, 2.4; for Europe, 1.6; for Latin America, 2.1; and for North America, 2. It takes 2.1 children per mother for a population to stabilize over time.
If today's fertility rate of 2.75 children for all women in the developing world continues, the world's population will reach 12 billion by 2050. The UN, however, projects the fertility rate will fall to 2.05 by 2045-50.
"It is unlikely the world's population will double again – ever," Ms. Zlotnik says. (Between 1950 and 2000, it did double.)
The rapid rise in the world's population has long been of concern to many. Vicky Markham, director of the Center for Environment and Population, in New Canaan, Conn., points out how all those extra people will need more space, food, water, and other natural resources. Fulfilling those needs could worsen global warming and harm other species on Earth. "It's pretty formidable," she says. And also unsustainable.
As if that weren't enough, a new study sees a political threat from rapid population growth. There is a correlation between countries with very young populations and those experiencing civic conflict, says Elizabeth Leahy, author of a report for Population Action International (PAI), a Washington advocacy group. This is relevant to the conflicts in Iraq, Afghanistan, Darfur (Sudan), and Gaza, for example.
Between 1970 and 1999, 80 percent of all civil conflicts that caused at least 25 deaths occurred in countries in which 60 percent or more of the population was under age 30, her study finds.
"It's a very complex issue," Ms. Leahy says. "There are multiple factors at play."
Nonetheless, her thesis is that governments and businesses in countries with young populations have a difficult time providing so many youths with education and "meaningful employment." The result can feed unrest and conflict.
Women in Iraq, where 69 percent of the population is under 30, have an average of 4.2 children. Afghan women have seven children. There, some 73 percent of the people are under 30. In Sudan, where women have an average of four children, 68 percent of the population is under 30.
Other nations with high birthrates include Pakistan, Nigeria, Somalia, Ethiopia, Kenya, Chad, Niger, and Yemen.
Zlotnik says the Leahy study is "a bit of an exaggeration." She notes that the world's most destructive and deadly wars have occurred in rich nations with older populations. But the PAI study points out that the eight new civil conflicts between 2000 and 2004 have risen in nations with very young populations.
Key remedies, according to Leahy, include improving access in poor nations to family planning and reproductive health services plus more equitable access to education and economic opportunities for women.