These new projections replace those that the United Nations published in 2017. The calculations have been revised upwards or downwards according to the countries or regions. For example, in the medium scenario, the figure for China in 2100 is 44 million higher than that in the 2017 projections (4% more). In contrast, for India, it is down 66 million (4% less). The same goes for Africa as a whole, whose projected population in 2100 is reduced by 187 million (-4%). For the planet as a whole, the upward and downward revisions offset each other, but only partly. According to the medium scenario, the global total for 2050 is projected to be 37 million fewer people than in the previous projections (-0.4%) and 309 million fewer in 2100 (-3%). [...]
The first time the United Nations published population projections up to 2100 was in 1981, and their medium scenario predicted then that the world population would reach 10.5 billion that year. The June 2019 projections suggest a figure of 10.9 billion – 0.4 billion higher. While the world total is slightly higher, it conceals a radical change in population distribution across the different continents. In 1981, the population of Asia was projected to reach 5.9 billion by 2100, but in 2019 the figure was revised downward to 4.7 billion (20% less). Likewise, for Latin America, the figure of 1,187 million in 2100 was lowered to 680 million (a decrease of about 43%). For Africa, on the other hand, the 1981 projections were 2.2 billion for 2100, while the 2019 projections have nearly doubled this figure to 4.3 billion (see Figure 2 below).
Where do these changes come from? The population of a country or continent changes because of fertility and mortality. Migration is also a factor, but to a lesser extent for many countries and with zero effect worldwide. It is therefore the assumptions on mortality and fertility that affect projections. For mortality, it declined faster than imagined 40 years ago, especially for children, which led to more rapid growth. The AIDS epidemic was certainly not anticipated at the time, and Africa has paid the heaviest cost. But the excess mortality it has caused will have lasted only one-time, and life expectancy has begun to increase again in recent years and relatively quickly. AIDS has had little effect on the demographic vitality of Africa.
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