This is an extract from the
nature.com website but I’m having trouble accessing it. Maybe others will have more success.
Interesting article as not everyone sees our imminent doom!
World Population set to decline
The past century’s world population surge has led many to wonder how the globe will sustain the ever-growing horde of humanity. A new study suggests that it may not have to: the world’s population may peak as soon as 2070, then start to decline.
There is an 85% chance that the population will stop growing before 2100, the model says. Unlike most, it does not produce just one prediction, but a range of possible futures, each with a certain probability of occurring.
The main message is that the population could rise from its present level of 6 billion to about 9 billion in 2070, then sink to 8.4 billion in 2100. This is one billion fewer than a United Nations estimate.
Such a prospect should cheer those worrying about food supplies and the human impact on the environment, says Wolfgang Lutz of the International Institute for Applied Systems Analysis in Laxenburg, Austria, who led the study. His model does, however, raise the spectre of an increasingly elderly society.
The United Nations estimate assumes that fertility rates will eventually stabilize at the replacement level of two children per mother. But most countries with declining populations have dipped well below that level, Lutz says. “We assume that as a society modernizes, the fertility rate goes down to between 1.5 and 2 children per woman.”
The model predicts a huge geographic redistribution of the population. Europe’s share is expected to dwindle from its present 10% to 6% by 2100; Africa’s will soar from 13% to 22%.
“The world is becoming less European, less white, less North American,” agrees John Bongaarts, of the Population Council, a charitable research organization in New York. “The voice of the southern countries will grow, because they will represent more and more of humanity.”
The model depicts a greying population, as fewer babies are born and life-expectancy increases. By 2100, the proportion of people over the age of 60 will have leapt from today’s 10% to 34%, the model predicts.
Caring for this elderly population will be a challenge, says Nico Keilman, a demographer at the University of Oslo. “China is already facing an enormous pension problem,” he says.
But many societies may have what Lutz describes as a “window of opportunity” before this ageing occurs, when both the elderly and child populations will be relatively small. During this time, countries could experience an economic boom, with many women in the workforce and few children to support.
“Some say the miracle of the Asian tiger economies of South Korea, Singapore and Thailand is being caused by this window of opportunity,” Lutz says. Europe is already well past this period, he adds.
It can be risky to make too many bets about what will happen 100 years from now, Bongaarts warns. “The theory that the population will reach a peak by 2100 is quite plausible, but the future is very uncertain,” he says.
Lutz’s model tries to deal with this uncertainty by considering two thousand different simulations of future fertility and mortality rates, and looking at the distribution of results.
This kind of forecast could be invaluable to policy-makers, Keilman says, providing them with possible futures and the probability of each.