Aids and fewer fertile women slow world population growth rates

The world population is likely to increase to more than 9 billion by the middle of this century, roughly 50 per cent higher than it is now, according to a new study by the US Census Bureau.

The world population is likely to increase to more than 9 billion by the middle of this century, roughly 50 per cent higher than it is now, according to a new study by the US Census Bureau.

But the exponential growth of the past 15 years is expected to slow significantly as some populations age and others are ravaged by Aids.

The Bureau calculated that the world is currently adding population at a rate of 1.2 per cent per year. That means 74 million new human beings every 12 months, and the equivalent of the population of western Europe every five years.

There has, however, been a reversal in the rate of growth since population hit in the 6 billion mark in June 1999. It took just 12 years for the population to jump from 5 to 6 billion - the fastest billion ever. However, it is likely to take 14 years to reach 7 billion, a further 15 years to get to 8 billion, and another 20 years to reach 9 billion. The overall growth rate is expected to slow to 0.42 per cent by 2050.

Already, 88 countries have fertility rates below the point where current population levels will be maintained. By 2050, that is projected to be true for the whole world. The primary reason for this slowing, the Census Bureau said, is that fertile women of child-bearing age are a shrinking proportion of the overall population. Largely, this is the result of people living longer. In 2002, people over the age of 65 made up 7 per cent of the world's population. By 2050, that figure is expected to leap to 17 per cent.

Among the many unknowns in these calculations, however, are two factors. One is the availability of contraceptives, and the other is the continuing devastating effect of Aids.

Some 20 million people are believed to have died of Aids so far, and another 40 million are believed to be infected with the HIV virus. Barring a major medical breakthrough, most of these people are expected to die in the next 10 years or so. In parts of Africa, this could bring the average life expectancy down as low as 30 by 2010, a rate not seen in the past 100 years.

There is, however, some hope for the future, the Bureau said. "If prevention of mother-to-child transmission programmes are dramatically scaled up," it wrote, then the course of future child mortality rates can be changed.

"Moreover, several countries, including Thailand, Senegal, and Uganda, have managed to stem the tide of the pandemic. These examples give hope that the Aids pandemic can be successfully curtailed." On the issue of birth control, the Bureau reported: "Though contraceptive prevalence has risen dramatically since the 1960s, there are at least 100 million women in the world's developing countries today who would like to space or limit their pregnancies but are not using contraception.

"These women are found in greater numbers in Asia than in other world regions but make up higher proportions of the populations of Sub-Saharan African countries than of countries in other parts of the world." The Bureau's figures were based on purely statistical projections and did not factor in other imponderables such as the possibility of major wars or the likely impact of greatly increased populations on food supply and other environmental considerations.

They are, however, broadly in line with other population estimates by the United Nations and from other authoritative sources. According to the Popular Reference Bureau, a private research group, birth rates are currently higher in India than they are in China. At current rates, India's population is likely to rise more than 50 per cent to 1.6 billion by 2050, which would cause it to overtake China as the world's most populous country. Those trends are, however, subject to change.

The Census Bureau's own projections have been modified slightly as population trends have shifted. In 1998, the Bureau forecast a world population of 9.3 billion by 2050. Now its best estimate is 9.1 billion.