The world population passed the 8 billion mark last year. While it is growing less fast than before and shrinking in an increasing number of rich countries (recently also including China), India's population will continue to grow for several decades and Africa's for much longer. Between 2000 and 2022, Sub-Saharan Africa's (SSA) population increased by 79% from 671 million to 1.2 billion. According to the UN's latest projection, it will grow to 2.1 billion by 2050: still a growth by 75%. However, other projections arrive at different results (see text box).

The UN figures in particular are huge. They contrast with developments in the rest of the world, where the population is expected to stop growing or even start shrinking over the course of this century (Figure 1). Currently, China, India and Africa have roughly equal populations, but the demographic futures of the three are completely different. Given the low median age of the African population (18.8 years), continued growth to nearly 2 billion people by 2050 is already almost inevitable (the so-called "demographic momentum"). Looking at the entire century, the UN expects a halving of the population size in China, further growth in India until around 2060 followed by shrinkage, but continued growth in Africa beyond the end of the century and already a tripling by 2100!

Divergent population projections for Sub-Saharan Africa

There are several authoritative projections of world population. The UN forecast ("World Population Prospects") is the best known, and is the most widely used, including in this article. Three other well-known projections are:
  • those of the Wittgenstein Center for Demography and Global Human Capital. These projections, the so-called "Shared Socioeconomic Pathways SSP scenarios," are widely cited and have also been used for the climate reports of the IPCC;
  • those of the Institute for Health Metrics and Evaluation (IHME), associated with the Global Burden of Disease project of the journal The Lancet;
  • the most recent: those of the Club of Rome.

These projections vary quite a bit, both in terms of methods and results. The UN forecast is a form of extrapolation of past trends based on the model of demographic transition. The other forecasts use information on the main determinants of demographic transition. The Wittgenstein forecast is based on the educational level of the population and the IMHE forecast adds both educational level and the use of contraception as determinants.

The Club of Rome forecast is the most complex because it models population development in an integrated system, that is, in conjunction with the economy and the ecological environment, with all domains influencing each other. In this model, income plays an important role, not education, and there is also feedback from climate change on population development.

Each study uses a number of variants or scenarios that indicate the uncertainty in the outcomes. For example, in addition to the medium variant, which is considered the most likely, the UN also produces a low and a high variant. In the medium variant, the number of children per woman in SSA is assumed to fall to 2.0 by 2100, when the number of inhabitants will be 3.4 billion inhabitants. In the high variant, the assumption is 2.5 and in the low variant, 1.5 children per woman. Half a child more or less per woman has huge effects on the final population size in 2100: 4.7 and 2.4 billion inhabitants, respectively, so almost a factor of 2!

Figure 1. Four population projections for Sub-Saharan Africa.
Figure 1. Four population projections for Sub-Saharan Africa.

The differences between the projections of the various studies are also large, but limiting ourselves to the most likely projections (Figure 1), the differences until 2050 between three of the four projections are not too large: 1.9 billion (in WC's baseline scenario SSP2) versus 2.1 billion (UN and IHME). However, the Club of Rome's most likely scenario, titled Too Little Too Late, differs greatly from this, with a forecast of "only" 1.6 billion inhabitants in SSA in 2050. For 2100, the differences between the projections are even larger. In the Club of Rome scenario, the population of Sub-Saharan Africa by the end of this century will be 950 million, even smaller than today's! This is mainly due to the assumed strong inhibiting effect of rising incomes on childbearing.

Source: Leo van Wissen (2023). Prognoses van de wereldbevolking: welke moeten we vertrouwen? Demos, 39 (5), 26 May 2023.

No wonder more and more people are worried about Africa. Some fear a population explosion that will lead to massive hunger and poverty, as well as mass emigration, especially to Europe.1 There are also concerns about rapid population growth among African scholars. By contrast, several opinion leaders and politicians see population growth as a great opportunity. A young active population can give the economies of African countries a huge boost, a "demographic dividend," is the thinking. Moreover, labour outside Africa will become scarce because of the ongoing aging of the population, which will make emigration increasingly rewarding and will also benefit the sending country if the migrants send remittances to their families - today already one of the largest capital flows to these countries.

Figure 2. Actual and projected population trends by world region, 1950-2100. Source: UN World Population Prospects 2022.
Figure 2. Actual and projected population trends by world region, 1950-2100.
Source: UN World Population Prospects 2022.

The debate about population growth is not infrequently polarized, ideological, simplistic and distorted by misunderstandings. To provide some clarity, in the next article we will discuss five misconceptions and half-truths about the issue. The third article follows six misconceptions and half-truths about solutions, always with a focus on SSA.

1. In the Netherlands, Frits Bolkestein of the right-wing liberal party VVD, was one of the first to sound the alarm with an opinion article in newspaper NRC in 2018: “Migratie afremmen kan maar op één manier” (“Slowing migration can only be done in one way”).

Thanks to Henk Breman, Ken Giller and Henk Rolink for their comments and suggestions.

Leo van Wissen is professor of Economic Demography at the University of Groningen.
Wouter van der Weijden is an environmental biologist and director of the Center for Agriculture and Environment Foundation.