Lucy Hodges reports on the challenges facing a world with six billion inhabitants
The statistics are sobering. Global population, which stands at 5.7 billion, is expected to almost double by the middle of the next century. It took until 1804 for the world to breed one billion people; by 1974 we reached four billion; the fifth billion came in 1987; and the sixth will arrive shortly.
But how much does rapid population growth matter, and what should be done about it? For biologists and family planning experts, for example, population growth is a critical issue. "It is perhaps one of the greatest problems facing humankind at the moment," says Mark Laskin, assistant secretary general of the International Planned Parenthood Federation. For economists such as the American Julian Simon of the University of Maryland it does not matter because humans are innovative and, given market mechanisms, will find ways to deal with shortages of resources.
Many academics regard population growth as important largely because it interferes with the development of poor countries and others see it primarily as a problem for women, inasmuch as repeated pregnancies are a drain on women's health, labour and time.
The bulk of the increase is in the Third World, where resources are already stretched. Figures from the World Bank illustrate the problem dramatically. Between 1970 and 1985 the estimated proportion of the Third World's population in absolute poverty dropped from 52 per cent to 44 per cent. That decline was cause for celebration. But closer examination of the figures shows that the number of people living in absolute poverty in the world actually increased over the period by 212 million.
A more tendentious area for debate is the environment - the extent to which global warming and acid rain are linked to population growth. Everyone is agreed that the so-called global commons, the air and the oceans and the Amazon rainforest, are under pressure and that an ever-expanding population cannot help but put pressure on such resources. But what should be done? In the 1970s when the world woke up to the issue after publication of biologist Paul Erlich's book, The Population Bomb, the West began pouring money into family planning campaigns in the Third World. Some governments, notably China and India, ran programmes to force women to accept sterilisation and birth control.
Since then there has been a backlash by feminists and by people in the Third World. "There is a feeling in many developing countries that they do not want to have their policies dictated by developed countries," says Tom Gabriel, director of the Sir David Owen Population Centre at the University of Wales, Cardiff. The United Nations conference on population in Cairo in 1994 reflected that mood and put the emphasis squarely on individual rights to contraception rather than on imposing top-down targets.
Clearly, contraception would come in handy. There are large numbers of abortions: in some Latin American countries, for example, abortion is the main single cause of adult female mortality. But many of the experts argue that contraception is only one of a number of solutions to limiting population growth. Others are a reduction in child mortality - improving child health so that people do not feel the need to have such big families - and education.
World Bank figures show that girls who go to school turn into women who desire fewer children than their own mothers. Women with more than seven years of education tend to marry later than women with no education, with consequent delays in childbearing.
One or two people argue that contraception is almost irrelevant. For doctrinal reasons the Catholic Church is against what it calls artificial contraception, putting its faith instead in "natural" birth control. And World Bank economist Lant Pritchett says that all fertility decline is explained by lower desired fertility, not by availability of contraception.
If nothing is done to check the growth in the world's population, the suggestion is that the gap between haves and have-nots will widen, cities will face extreme pressures, because almost all developing country growth will be urban, and rapid urbanisation will contribute to pollution.
Is population growth in the Third World a problem? If so, how should we deal with it?
"I would say without doubt it is a problem. You have to deal with it on several different layers. We are all referring to rapid population growth in poor countries under conditions of high fertility. The more siblings a child has the more likely he is to be malnourished, the more likely he is to die young, and the less likely he, or particularly she, is to go to school. The large family is not good for children. Even with the parents, it's not at all clear, especially when you add that the wife is more likely to die. In Africa mothers have one chance in six of dying as a result of having a child.
"We don't know whether rapid population growth in poor countries is good or bad for economic growth. There's some suggestion that it's not.
There's quite a lot of concern on the environmental score. People have been pointing out for years that it's the rich countries where population isn't growing that have been destroying the environment more than poor countries, which is true. But that doesn't mean to say it's not a problem in developing countries. India is already the world's fifth or sixth largest emitter of greenhouse gases."
Paul Julian Simon
Economist, University of Maryland, United States.
"Every baby, and every additional person is a problem. Every parent knows that. But the baby is not just a problem. It is also a source of benefits. That's true of every investment. Getting a house is a problem, getting it built is an investment, but eventually it brings benefits. In the long run, human beings are the source of all our benefits. The problem with an awful lot of this is simply bad thinking. On balance people create a little more than they use over their lifetimes.
"Population economics is uncommonsensical in the extreme. The most important effects of population growth are very diffuse and very hard to see. All the benefits are hard to see, whereas all the bad things are obvious. Which is why again and again we get all these stories presenting the view that population growth is all bad."
Population and environment consultant.
"I think the environment issue is the one reason why western countries should be concerned about population growth in the Third World. The more people there are in newly industrialising counties, the more consumers there will be in the year 2050, presumably consuming at pretty close to the level that we are currently consuming, which is actually impossible. Massive changes in technology will be needed to accommodate that. And if we can keep the total towards the lower end, then our task will be easier.
"But it's important that the environmental concern should never be used as an excuse for hasty programmes, nor programmes that violate women's rights. The Chinese are very definitely violating women's rights. Family planning programmes ought to set out with a perspective of helping women improve their choices. They should not set out with any other perspective such as reducing population numbers.
LSE, one of the lead negotiators for the United Kingdom at the Cairo population conference 1994.
"It's a problem, but not the problem which some people allege. Clearly many governments in the Third World do perceive population growth as a serious problem and the extreme example is China with its strong government programme and the coercive practices that have gone on there.
"At the Cairo conference there was a strong emphasis on reproductive choice: the rights and needs of individual people, rather than governments, to control population. So often programmes which have clear targets to reduce fertility to a particular level spill over into coercive practices. The emphasis is on the right for everyone, especially women, to have access to the information and the means to have as many children as they wish".
Senior lecturer, Centre for Population Studies, London School of Hygiene and Tropical Medicine.
"Yes, I think it's a problem. I don't think it's for us to deal with it because unless the motivation to limit families comes from the individuals themselves, things that we do won't particularly help.
"I think the environment problems are overstated. A much more serious problem is that you can't keep up with the human resources you need to develop the population. If the population is growing at 3 per cent a year, you need 3 per cent more teachers each year - double the number of teachers every 17 years. If you want to actually increase the level of education of your population you've really got an uphill struggle. This is where population growth makes it verydifficult for a country to develop."
Campaign coordinator, public education, Catholic Fund for Overseas Development.
"The North really concentrates on population because it wants to apportion blame to the Third World. In fact 20 per cent of the population living in the North consumes 80 per cent of the world's resources. So, I would say population is not the only problem; the other is the distribution of the world's resources.
"We would not promote any programme that involved artificial contraception but that doesn't mean we are opposed to family planning. There are some benefits to natural family planning because it's not altering women's hormonal make-up. Cafod is completely opposed to any kind of coercion. There are so many basic rights that women don't have - education, access to water. The North keeps pushing this one solution - curbing population growth - and it's not the answer. "