In just over 70 years, the world’s population has more than tripled. If ne were 2.5 billion in 1950, on Tuesday November 15 we crossed the bar of 8 billion human beings. A symbolic threshold determined by a UN projection unveiled in mid-July on the occasion of World Population Day. Something to make you dizzy. Because, according to United Nations estimates, the Earth should have around 9.7 billion inhabitants in 2050 and around 10.4 billion around 2080.
And then ? Specialists anticipate a pause until around 2100, when demographers even expect stagnation, or even the start of a curve inflection. But how to explain this ceiling when, mathematically at least, one could imagine an infinite growth of the world population?
The number of children per woman is decreasing
For Gilles Pison, a researcher at the National Institute for Demographic Studies (INED), the fact that the world population peaked towards the end of the century, before potentially stagnating, is the result of trends already well known to specialists. “The demographer does not know how to predict catastrophes or sudden changes. So he prolongs today’s trendshe explains. And we observe that population growth continues, but at a rate that has been decelerating for 60 years already.
In demography, fertility corresponds to the average number of children per woman of childbearing age. However, this rate is falling all over the world, he explains. “It is a movement that does not date from yesterday.”
“The voluntary limitation of the number of children appeared two centuries ago, first in Europe and North America, before spreading to all continents.”
Gilles Pison, demographerat franceinfo
Today, Europeans and North Americans have an average of 1.5 children each, compared to 1.9 in Asia and 1.8 in Latin America. “In Africa, if there are just over four children per woman, on average, fertility is also declining there. he continues. Voluntary limitation of births should eventually become generalized there, as elsewhere. he notes, noting however a decrease which “takes place at a longer rate than what was observed in Latin America or Asia 40 years ago.”
While a sharp drop in fertility has been observed in several developed countries, the population increase expected in the coming decades will, according to the UN, be concentrated for more than half in eight countries, five African and three Asian: the Democratic Republic of Congo, Egypt, Ethiopia, Nigeria, Tanzania, Pakistan, India and the Philippines.
“There are now internal forces specific to each region of the world that limit reproduction”, explained demographer Christophe Z Guilmoto, a researcher at the Institute of Research for Development based at the Center for Human Sciences in New Delhi (India), in an interview granted in July to the JDD. Whatever, “women tend to have a maximum of two children in many countries. This is a far cry from the infinite growth that we worried about in the 1960s.”
Declining mortality linked to slow progress
With the fall in fertility, demographers take into account the average lengthening of life, linked to the fall in mortality. These two factors are “demographic transition”. And there too, “all the countries of the world have known it or know it”, underlines Gilles Pison, starting with Europeans and North Americans. In Asia and Latin America, the demographic transition started later, but it happened faster, he says. “These continents have benefited from advances in hygiene, as well as medicine,” continues the demographer.
Finally, in Africa, the last continent to have initiated these changes, “Mortality has fallen a lot – even if it is still there that it is highest – but the changes have been rapid”. Worldwide, “I‘average overall life expectancy has increased from 64.8 years in the early 1990s to 70 years today’, noted the UN in publishing its figures this summer.
Should we see a ceiling reached? In 2008, the demographer had published an article on this subject on Slate: if the infant and maternal mortality rate, already low, can still be significantly reduced, it “has virtually no effect on life expectancy”he wrote. “This can only progress because of the successes achieved in the fight against adult mortality, in particular at high ages where deaths are increasingly concentrated.” However, if the ceilings determined in recent decades have been exceeded, successes in this field are now the result of slow scientific and medical progress (as in the fight against cancer or degenerative diseases).
Changing lifestyles to respect planetary resources
The United Nations projection, which counts on a population that will peak at 10.4 billion inhabitants at the end of this century, coexists with other scenarios: the United Nations estimates that there is a 95% chance that the population, in 2100, will be between 8.9 and 12.4 billion, explains Gilles Pison. The highest fork, “very unlikely”even climbs to 15 billion human beings.
The demographer stresses that, whatever the scenario, the available resources should be shared equally and fairly. To those who fear a planet on which we would be “too many”he replies that the problem is not the number but our consumption patterns.
“It’s not a question of demography. If we were only a billion on Earth and we lived like an inhabitant of the countries of the North, then it would not be tenable.”
Gilles Pison, demographerat franceinfo
“It is a minority that has been responsible for the bulk of global warming, so it is clear that the question is not the number of humans but that of their way of life. While it is illusory to think to be able to change the evolution curve by 2050, lifestyles must already be more respectful of the environment and biodiversity.”