Some time this year – the United Nations says it will be on Oct. 31 – the seven billionth person on Earth will be born. Based on statistical probabilities, he will likely be a boy born to Hindu parents in a village in Uttar Pradesh, India's poorest and most populous state. Although he may have access to clean drinking water, he likely won't have a toilet or electricity and will have only about a 60-per-cent chance of learning to read and write as he grows up.
The milestone birth raises some crucial questions for anyone concerned that the planet is nearing its saturation point. How many people can it support? Do we need to stop population growth? And if so, how?
We asked some of the experts to help sort through the numbers.
Is the population growing out of control?
It has grown at an astounding rate since the beginning of the 20th century. Only in the early 1800s, after most of human history had passed, did we reach the one billion mark; it took only another 100 years to double that and just 12 more to add the most recent billion. And although the explosion is slowing, it is far from over. There are more women than ever in their childbearing years, and the UN predicts the population will keep growing until at least the end of the century.
Hania Zlotnik, director of the UN Population Division, says all of this could have been much worse if not for rapid changes to the lives of women. Women are better educated, have more work opportunities and pressures, and get better access to birth control, and that has led to a dramatic drop in fertility over the last two generations. Worldwide, women now have half as many children as they did in the 1960s and just slightly more than is needed to replace and maintain the current population.
However, the drop in fertility rates has stalled in the world's 48 least-developed countries and is still far above replacement levels. Those countries together will account for most of the world's population growth until the end of the century. That could mean hundreds of millions more people living in poverty and even greater social and economic disparities between the developed and developing world.
Is seven billion too many people for the world to sustain?
Demographers have been trying to answer that question since English economist Thomas Malthus declared in 1798 that factors such as war, disease and famine would keep the population from growing for too long. No one has come up with an answer, but many experts argue that consumption is at least as big a problem as population.
Bob Engleman, executive director of the Worldwatch Institute, says that short of coercion, there is little more that could be done to quickly reduce birth rates any further. Reducing consumption, on the other hand, could provide almost immediate relief to a stressed planet.
China is a case in point. Carbon emissions there are growing even though the country's fertility rate is below replacement levels. And the developed world consumes far more than its fair share based on population. According to Princeton University's Environmental Institute, the wealthiest 7 per cent of the world population produces 50 per cent of the world's carbon emissions. The poorest 50 per cent produces 7 per cent of the world's population.
In terms of food, Joel Cohen, author of the book How Many People Can the Earth Support?, argues the world already grows enough grain to feed 10 billion people an "adequate vegetarian diet," but the problem is how it is distributed. More than half is used for fuel or to produce meat for tables in rich countries.
How big a problem is aging in developed countries?
Birth rates have dipped below replacement levels in developed countries, and it's expected that an aging population will seriously stress those countries' economic and social systems. In Japan, for example, nearly a quarter of the population is aged 65 or older. If current trends continue, Japan will have only one person working for every retiree by 2050. In Canada, there will be two workers for every retiree.
"That problem does not have an easy solution," says Carl Haub, senior demographer at the Population Reference Bureau. "There's going to be a real tension and it will increase."
Mr. Haub says that once women have decided to have fewer children, it's difficult to convince them to have more, so immigration is the only way to maintain the population in developed countries. If immigration policies are to succeed, he says, countries like Japan, which is traditionally closed to foreigners, "will have to get over the fact they will not be a homogenous population anymore."
If birth rates remain high in developing countries, why not impose strict population control programs like China's one-child policy?
Population control programs such as restricting the number of births were abandoned at the UN Cairo Conference on Population and Development in 1994 and are generally considered a gross violation of human rights. Even if that was not the case, Mr. Haub says such programs would likely fail in the countries where birth rates are highest, most of which are in sub-Saharan Africa.
African societies are less structured, making such policies hard to implement. The desire to have large families can be firmly entrenched in social, cultural and religious beliefs and a lack of education and is "extremely difficult" to change, he adds. In Niger, for example, surveys show that woman think of nine children as an ideal family and men want to have 11 children.
Corruption plagues the area and for many governments the will to stop population growth "just isn't there," Mr. Haub adds. Even if there was a will, societal and tribal rivalries are often so intense that any policy would likely be ignored.
"I don't think many people would knuckle under to the government because they just have no respect for them in the first place," he says.
Countries could get the same results, he says, by ensuring effective birth control is available to the 25 per cent of women who cannot get it, raising levels of education and somehow increasing the age of marriage.
Editor's note: Hania Zlotnik is the director of the UN Population Division. Incorrect information appeared in a previous version of this article. This online version has been corrected.