AIDS's Shadow Cools Global Population Forecast

AIDS's Shadow Cools Global Population Forecast

By Joby Warrick
Washington Post Staff Writer
Wednesday, October 28, 1998

The global AIDS epidemic is forcing demographers to dramatically scale back predictions for population growth over the next century, as some African nations brace for losses as high as a quarter of all adults, according to a United Nations study to be released today.

The report, the first to incorporate new U.N. findings on AIDS' rapid spread in the developing world, will forecast a worldwide population of 8.9 billion by the year 2050 – a 50 percent jump from today's 5.9 billion people but well short of the 9.4 billion population officials were predicting just two years ago.

The lower estimate is based partly on falling fertility rates, which are now being seen in all regions of the world. But it also reflects what the authors called a "devastating mortality toll" from AIDS. After factoring in the new data, forecasters dropped their population estimates for the hardest-hit countries by as much as 23 percent. Barring a cure or a wider distribution of Western AIDS drugs, they say, soaring death rates could begin to depress population growth in some countries within a decade.

"This is a virus that still doesn't have a cure," said Population Division Director Joseph Chamie, who will present the findings at U.N. headquarters in New York. "Unless something happens, we're going to see the mortality pattern emerge that we've projected here."

The new study also brings worrisome news on other fronts, including higher new estimates of the proportion of elderly people in the population, as well as a prediction that older adults will outnumber children for the first time by 2050.

And, despite lower growth rates, the report predicts that humans will pass the 9 billion mark sometime in the next century, with almost all the growth occurring in poorer countries already struggling to feed and shelter their populations.

But perhaps the most striking finding was the scale of the impact of AIDS on population growth. Chamie said the epidemic was one of the main reasons for the lower estimate for population growth, explaining that new U.N. statistics released over the summer had shown "extremely shocking levels of prevalence." In nine African countries, HIV infects 10 percent of the population or more, and in Botswana more than 25 percent of adults have the human immunodeficiency virus (HIV).

While cocktails of expensive drugs have helped lower the AIDS death rate in Western countries, such treatments are generally out of reach in the developing world. As a result, Chamie said, the life expectancy in hard-hit African countries such as Botswana is already dropping and will plummet a full 20 years – from 61 to 41 – by the year 2025.

AIDS is now chief among a number of public health and environmental problems in the developing world that have helped depress population growth in ways few could have predicted two decades ago, according to longtime students of population trends. The emerging pattern is described as "population fatigue" by Lester Brown, founder of the Washington-based think tank Worldwatch Institute who anticipated the U.N. study's conclusions in a report last month.

"This reversal in the death rate trend marks a tragic new development in world demography," Brown said. "Some developing countries with rapidly growing populations are now headed for population stability in a matter of years – not because of falling birth rates, but because of rapidly rising death rates."

The projection of 8.9 billion people by the year 2050 is described as a middle-range forecast based on estimated fertility rates over the next half-century. The U.N. report says the 2050 global census could go as high as 10.7 billion or as low as 7.3 billion.

The study is the lastest biennial assessment by the Population Division, an arm of the U.N. Department of Economic and Social Affairs, and is based on a scientific assessment of population data from 228 countries, from the tiny Pacific island of Pitcairn, with 46 people, to China's 1.3 billion.

Despite AIDS and declining fertility rates, the report projects continuing rapid growth. The planet will continue to add another billion people every 13 to 15 years, as it has since the 1960s. Virtually all the increase – about 97 percent – is occurring in developing countries.

Much of the growth is due to longer life expectancies, including a dramatic increase in the number of elderly people. In the first such projection of its kind, the U.N. report predicts a six-fold increase in the number of people aged 80 and above over the next half century. By the year 2050, it says, the world for the first time will have more older people than children.

In many Western countries, especially Europe and Japan, the salient demographic trends of the next century include not only aging but a continued shrinking of the population. More than 61 countries have already reached, or dipped below, the "replacement" fertility rate of 2.1 children per woman.

Some European countries have remained below the replacement rate for more than two decades, and a few, such as Spain and Bulgaria, have dropped as low as 1.3 children per woman, a rate "which a generation ago would have been considered highly improbable," the report says.

Overall, the world's population stood at about 5.9 billion in the middle of this year and will cross the 6 billion mark some time next year. But the rate of growth, 1.3 percent per year, has been declining steady and is down sharply from the peak 2.04 percent growth rate of the late 1960s.

Rapid population growth is mainly a phenomenon of the late 20th century. From a global population of about 300 million around the time of Christ, it took more than 1,800 years for the human race to surpass the 1 billion mark. It took another 123 years, until 1927, to reach 2 billion. But the real population "boom" began in the 1950s, as modernization slashed infant mortality rates and increased life expectancy in developing countries.

The dire predictions of 1960s Malthusians have failed to materialize, as improvements in education and contraception suppressed fertility rates more rapidly than anyone predicted. Still, the prospect of an additional 3 billion people in 50 years continues to pose grave concerns, said the Worldwatch Institute's Brown.

"The question is not whether population growth will slow in the developing countries," said Brown, "but whether it will slow because societies quickly shift to smaller families or because ecological collapse and social disintegration cause death rates to rise."