Slow but steady contraction in the north, vigorous and sustained expansion in Africa; seven billion of us by October this year, eight billion sometime around 2025. The latest United Nations population figures provide a dramatic glimpse of how the demographic map of the planet is being reshaped.
For the latest revision of its biennial “World Population Prospects,” the U.N. Population Division has extended its forecasts by 50 years, to 2100. Long-term forecasts must be taken with a grain of salt — they “have no operational role,” as the French demographer Hervé Le Bras has written; they just help “staging and exaggerating today’s fears.”
Still, the margins of error allow for a fairly reliable picture of the world’s population in the decades to come. And what matters more is the breakdown of the aggregate figures, as their distribution holds far-reaching consequences.
For this, demography delivers a high level of certainty. The women liable to give birth within a generation are already born; life expectancy and mortality indexes evolve slowly. The most volatile factor is actually the fertility rate — the number of children per woman. Only if this rate is above the generation replacement level of 2.1 will there be a natural increase of a population. When it hovers between 5 and 7, as it does in some 20 countries, the “compounded interest” effect is extremely powerful.
Unsurprisingly, Asia remains the largest human reservoir, holding more than 60 percent of the world’s population — a proportion that should still be around 55 percent by 2050.
What is most striking, though, is the unabated demographic swelling of Africa. Africa’s population has almost doubled between 1975 and 2000, growing from 416 to 811 million; it will add another 75 percent to reach 1.4 billion people in 2025, and presumably another 55 percent to reach the staggering figure of 2.2 billion by mid-century.
The main reason is that the demographic transition — the decrease of birth rates following the drop of death rates when a country takes off — is slow to occur in the least developed countries. With the exception of Afghanistan, Timor and Yemen, all such countries, with current fertility rates above 4.5 children per woman, are located in sub-Saharan Africa — and there are some 25 of them.
The U.N. assumes this rate will decrease steadily from five to three children per woman, which is considered the medium. Still the population of Africa as a whole is expected to keep growing briskly, from only 9 percent of the world’s population in 1950 to 24 percent by 2050. The absolute figures will have increased tenfold within that century.
And while countries such as Nigeria (230 million in 2025, 390 million in 2050); Ethiopia (110 million and 145 million) and Congo (95 million and 148 million) have since long been identified as the demographic giants of sub-Saharan Africa, new applicants are following suit.
With a population of 45 million inhabitants today and a fertility rate of 5.5, Tanzania is on the path toward 71 million in 2025 and 138 million in 2050. Kenya is expected to jump from 41 million to 59 million and then to 97 million in that same time span, while Uganda might reach the 100 million mark after mid-century.
In the 1960s and 1970s the population growth rates — then of the same magnitude as those of sub-Saharan Africa today — fostered a number of controversies in the West about the capacity of the earth to feed a constantly growing mankind. They also prompted birth-control policies in a number of Third World countries.
The slowing of the exponential curve of demography after the 1970s muted the neo-Malthusian voices. But the toll that demographic growth in Africa will take on an already stressed ecosystem will no doubt reopen those debates.
Another consequence of the growth curve is the pressure to emigrate generated by the annual arrival on the African labor markets of some 20 million youths. That bulge is liable to increase year after year, reaching 40 million by 2050.
The migratory pressure will be directed in the first place toward Europe, whose population, in sharp contrast with Africa’s, is bound to age and stagnate.
Here the figures provided by the U.N. do not show any reverse trend. Even though they assume a surge in fertility rates close to the generation replacement levels, within a decade Europe — for the first time in peacetime — will have no natural increase of its population. Russia’s population has been declining for two decades; more recently so has Germany’s (and Japan’s). The issue is not only one of decline in absolute figures, but also one of a graying population and a shrinking workforce.
Not all European countries are equally affected. France, Ireland, Britain and some Nordic countries have fertility rates quite close to the generation replacement rate and are not threatened by demographic decline. But this does not change the trends for Europe as a whole, nor the fact that the Continent will remain a desired destination for immigrants from the South.
Another French demographer, Alfred Sauvy, once said that the 21st century would be “the century of demographic aging.” One should add that it might be the century of immigration.
The United States and some other countries have long turned immigration into a public policy that, despite some stumbling blocks, has helped preserve a balanced age pyramid. In Europe, recent developments have shown the extent to which immigration can corrode the European construction.
“Demography is destiny,” says the maxim attributed to Auguste Comte. It is about time for Europeans to take their destiny into their hands and to address it from both ends: the urgent need for massive development in Africa and sound management of the inescapable migratory flows from south to north.
By Pierre Buhler, a former French diplomat and associate professor at Sciences Po, Paris.