Planet Earth will host 7 billion humans by the end of October 2011.
Although that's a daunting number, the rate of increase is slowing from its high point of over 2% in 1968. Still, this year's 1.1% increase means some 78 million people will be added to the global population in 2011.
The human population reached 1 billion in the early 19th century, and it took more than 100 years to reach 2 billion. After that, the intervals between billions grew even shorter: we added the third billion in 33 years, the fourth in 14 years, the fifth in 13 years, and the sixth and seventh in 12 years each.
Anyone alive today who was born by 1940 has seen our numbers triple. The most widely cited United Nations projection shows world population hitting 8 billion in 2025 and 10 billion before the end of this century.
With populations stabilizing in much of the industrial world, almost all population growth in the near future is expected to occur in developing countries. Of the 2.3 billion people to be added by 2050, more than a billion will live in sub-Saharan Africa. The Indian subcontinent will add some 630 million people.
Global Fertility Levels
Differences in population growth rates are largely due to varying fertility levels. Global fertility has dropped from close to 5 births per woman in the 1950s to 2.5 births per woman today.
Over 40% of the world's people live in countries where fertility is below replacement level. But fertility varies widely across countries. In Niger, women have more than 7 children on average; in the US the average is close to 2, and in Japan it is less than 1.5.
Evidence suggests that many women in poor, fast-growing countries would have fewer children if they had the resources and freedom to plan the number and timing of their births. An estimated 215 million women in the developing world don't have access to family planning resources.
Worldwide, about 40% of pregnancies are unintended. A
study from the Futures Group and
calculations by population expert Robert Engelman indicate that if all women were able to become pregnant only when they chose to, global fertility would drop close to or even below replacement level, greatly reducing population growth.
Voluntary family planning programs have proved effective in lowering fertility rates. In Mexico, for instance, a national family planning program started in the mid-1970s with support from the US and the United Nations has helped raise contraceptive use from less than one fourth to two thirds of women. Fertility has fallen from roughly 7 to 2.2 births per woman.
Surveys show that across societies, women with more education tend to have fewer, healthier children. In Mali, for example, women with no schooling have 7 children on average, while those with at least a secondary education have fewer than 4. Yet many women around the world still lack access to education.
In 1994, delegates from 179 countries at the International Conference on Population and Development in Cairo, Egypt, recognized reproductive health and family planning as fundamental human rights. Participating countries agreed on the goal of universal, voluntary access to reproductive health and family planning services by 2015, pledging to invest $17 billion per year by 2000 and $22 billion per year by 2015.
Thus far, however, contributions have fallen far short of pledges, and close to $20 billion per year above current expenditures is still needed. This investment could prevent 53 million unwanted pregnancies each year, improve infant and maternal health, and reduce associated health care costs.
