Between 1650 and 1850, the world’s population more than doubled, from half a billion to 1.13 billion. In the next 100 years, it more than doubled again, to 2.5 billion. Today some 5.8 billion people live on Earth. But a new study reports that though the population may hit 10.6 billion in the next 80 years, it will probably never double again. I don’t believe in a global doomsday scenario, says Wolfgang Lutz, a demographer at the International Institute for Applied Systems Analysis in Laxenburg, Austria.
Lutz believes that most population projections are flawed. International agencies put together population projections that were rather mechanistic and did not include too many scientists, he says. A small in-house group defined what assumptions were going to be made. So Lutz assembled a panel of 20 experts in the fields of fertility, mortality, and migration--the three factors that immediately affect populations--to discuss future trends.
In the panel’s most likely scenario, population will peak at 10.6 billion in the latter half of the next century and then will start to fall. Though life expectancy is predicted to increase in industrialized countries, less developed countries may suffer increased mortality due to infectious diseases. But the driving factor in the panel’s prediction is declining fertility rates.
In the past five years, fertility rates have fallen even in countries where they have been constantly high. Lutz and his colleagues interpret this as the start of a long-term downward trend in fertility rates worldwide, due to an increase in educated women. Also, as more people leave rural areas for cities, family size is expected to drop because large families are not assets for urban dwellers. Fertility rates will eventually drop below replacement level, the panel predicts, to around 1.7 children per woman, resulting in a shrinking population.
But the end of population growth brings its share of troubles. China’s one-child-per-family policy, Lutz points out, will bring about an abrupt aging of the population, a prospect many other countries also face. In China, it had been lots of children and grandchildren looking after parents, he says. Now if you have two generations of one-child families, it would mean that a single person is in charge of four grandparents. That’s going to be a big issue.