(EnergyAsia, October 21 2011, Friday) — The following is an edited version of an essay by Brigid Fitzgerald Reading of the Earth Policy Institute in Washington DC, USA.

The number of people in the world is expected to reach seven billion by the end of this month. Our rate of increase continues to slow from the high point of over 2% in 1968. Still, this year’s 1.1% increase means a net increase of 78 million people in 2011.

The human population did not reach one billion until the early nineteenth century, and it took more than 100 years to reach two 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 born by 1940 has seen our numbers triple. The UN projects the world population to reach eight billion in 2025 and 10 billion before the end of this century.

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.

Differences in population growth rates are largely due to varying fertility levels. Global fertility has dropped from close to five births per woman in the 1950s to 2.5 births per woman today.

Over 40% of the world lives in countries where fertility is below replacement level. But fertility varies widely across countries. In Niger, women have more than seven children on average; in the US the average is close to two, 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 do not have access to the family planning resources they need. Worldwide, 40% of pregnancies are unintended.

A Futures Group study 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 programmes have proved effective in lowering fertility rates. In Mexico, a national family planning programme started in the mid-1970s 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.

Across societies, women with more education tend to have fewer, healthier children. 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, recognised 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 US$17 billion per year by 2000 and US$22 billion per year by 2015.

But contributions have fallen far short of pledges, and US$20 billion per year is still needed. This investment could prevent 53 million unwanted pregnancies each year, improve infant and maternal health, and reduce associated health care costs.

Access to reproductive health care brings far-reaching benefits to individuals, families, and whole societies. When a woman can time her pregnancies, her education is less likely to be cut short by early motherhood. Female education and family planning reduce risks to child and maternal health and boost women’s chances of economic advancement. Smaller family sizes help raise families out of poverty.

When fertility declines quickly, reducing the number of young dependents relative to working-age adults, countries can experience what is known as the demographic bonus.

Governments can spend more per person on public services, families can spend more on each child, and more money is available to invest in economic development. This ‘bonus’ can kick-start a nation’s economy as seen, for instance, in the rapid development of Asian countries including South Korea and Taiwan in the 1970s and 1980s.

Some industrial countries are becoming concerned about aging populations. Japan has nearly doubled its share of the population aged 65 and over in the past 20 years. In industrial countries as a group, the share of the population aged 65 and over is expected to increase from 16% to 26% between now and 2050.

In contrast, the youthfulness of populations remains a challenge for developing countries as a group with almost 40% under the age of 20. Countries with large populations of young people and poor employment prospects are more prone to violence.

As the world’s population grows, less land and water are available for each person. Poor people, who often depend more immediately on natural resources and are less able to compete for dwindling supplies, bear the heaviest burden.

Rapidly growing populations stress their own local environments. In fast-growing Yemen, the population has increased four-fold over the last 40 years while the overpumping of aquifers has helped shrink the country’s grain harvest by one third. In Pakistan, the pressures of a large and fast-growing population have contributed to widespread deforestation and soil degradation, making the historic flooding events of the last two years even more destructive.

The UN population projections do not consider how the environmental problems we create, such as water scarcity and climate change, may limit our ability to grow. Whether we are able to sustain human civilisation depends on not only our numbers, but also the rate at which we consume the earth’s resources and create waste.

At the global level, we are already far overshooting the earth’s capacity to support us, even as some 1.4 billion people live in extreme poverty.

Another two billion people may be added to the world population by mid-century, many of them in places where hunger, poverty, and environmental degradation are already taking a high toll.

Supporting the human population will mean eliminating poverty, transitioning to an economy that is in sync with the earth, and securing every person’s health, education, and reproductive choice.

If we do not voluntarily stabilise population, we risk a much less humane end to growth as the ongoing destruction of the earth’s natural systems catches up with us.