“We are as frightened by the decline in fertility as by overpopulation,” notes Géraldine Duthé, research director at the National Institute of Demographic Studies (INED). If we say that we no longer have enough children, it’s a disaster. And when we announce 10 billion human beings by 2100, we cry about overpopulation. The latest study, published by the journal The Lancet last Thursday, which is based on figures from the Global Burden of Disease, is hardly more reassuring. According to her, more than half of the countries observe a fertility rate that is too low to maintain the level of their population. In 2020, she predicted a peak in the world population to 9.73 billion in 2064 before decreasing in 2100.
No better on the United Nations side. “On November 15, 2022, the world population reached 8 billion people,” we can read on its site. It took twelve years to go from 7 to 8 billion and it will take fifteen to go to 9 billion. According to forecasts from the international organization, in 2100, there will be around 10.4 billion people living together. Decline of humanity or overpopulation? Both, my captain.
Why can’t we prevent 10 billion humans on Earth from reaching?
“We will not escape this additional two billion, due to demographic inertia [le décalage entre la baisse de la natalité et la diminution de la population]. We cannot prevent it,” explains Gilles Pison, professor emeritus at the National Museum of Natural History, advisor to the management of INED and author of The World Population Atlas (Editions Autres). Even if women have few children, there are still twice as many births as deaths globally.
“In a population, if you have a lot of women who are old enough to have children, even if they have a little less than the generation before, you will have a lot of births,” adds Géraldine Duthé. There is a simple effect of inertia.” And the calculation doesn’t come out of nowhere. “We can estimate without too much error the babies who will be born because the women who will give birth to children in the next twenty-six years, for the most part, have already been born,” continues the demographer.
Won’t global warming decimate the population?
“It’s not the most likely,” retorts Gilles Pison. Most likely, today’s demographic trends will continue. Women and men are having fewer and fewer children all over the planet.” The estimates do not predict excess mortality linked to global warming, but rather migratory flows which could change demographic behavior. “We anticipate that people will move before dying there, it’s a more optimistic view of things. There will first be population movements,” underlines Géraldine Duthé. The researcher recalls that even major health crises like HIV-AIDS or Covid-19 have had no effect on the world population.
According to’World Health Organization (WHO), the total number of deaths associated directly or indirectly with the Covid-19 pandemic between January 1, 2020 and December 31, 2021 was approximately 14.9 million. The toll is significant but mortality has had a temporary effect on the weight of the world population. “The last example of a decline in the world population linked to a health crisis is the Black Death in the Middle Ages,” insists Géraldine Duthé. Today, it takes twelve years to go from one billion to another. A very strong cause of death has very little influence on the evolution of the population as a whole.” “The hypothesis that humanity will be decimated by a pandemic is not the most likely,” concludes Gilles Pison.
Isn’t the problem of infertility THE solution to overpopulation?
More and more couples are struggling to have a child. In 2022, infertility affected one in four couples according to figures published by the Biomedicine Agency. In mid-January, Emmanuel Macron even announced the launch of a “major plan” to fight against this “scourge”. One might believe that this infertility has an effect on the world population. But no. “It doesn’t change much in terms of fertility. When a middle-aged couple decides to have a child, there is a delay in conception which is already 5 or 6 months for normally fertile couples. Infertility does not prevent most couples from having children, it extends the time it takes to conceive,” points out Gilles Pison. The most important thing, according to him, is the desire to have children. “The decline in fertility on a global scale is not due to environmental or sterility problems, for the moment,” he analyzes. But to the desire (or not) to have a child.
Can we survive 10 billion?
“We could ask ourselves the same question for the 8 billion humans who populate the Earth today,” smiles Gilles Pison. Tomorrow, we will be 10 billion, but we will not be hundreds of billions.” According to him, we must work on lifestyles that are more respectful of the environment and biodiversity. “The real question, and on which the long-term survival of the human species depends, is ultimately less that of numbers than that of ways of life,” he observes. We, residents of the countries of Europe and the United States, have a special responsibility. Our activities are responsible for global warming, even if other countries have joined the fray. And our lifestyles serve as models for the entire planet.” In other words, let’s lead by example. We cannot fight against the two billion more human beings, but we can act on our behavior to promote responsible and sustainable lifestyles.
What will happen to all these old people?
The aging of the population systematically comes up in debates on pension reform. But the phenomenon concerns all countries. And its driving force is not life expectancy, but rather the drop in births. “Fewer children are being born, as a result, we have an elderly population, which is dependent and which must be taken care of,” warns Géraldine Duthé. “This is one of the major challenges of this century,” adds Gilles Pison. Demographic aging is occurring much more quickly in the countries of the South than it has in the countries of the North, where the decline in fertility and the lengthening of life began earlier. They had a little more time to see the problem coming and put pension systems in place.
“The countries of Asia, Latin America and Africa are experiencing the same developments with an extension of life and a reduction in fertility, but demographic aging is occurring much more quickly,” worries the demographer. And they are not prepared for it. We must hurry to put in place systems of collective solidarity if we do not want adults who have contributed to the economic development and growth of these countries to end their lives in poverty.” According to him, the phenomenon is almost more acute in these countries which are not prepared for the shock.