Population Scenarios for 2052 and Beyond: Dramatic Decline?
by Harald Siem
Harald Siem (Norwegian, born 1941) is a medical doctor with a master’s in public health, trained in Basel, Oxford, Oslo, and Harvard. He has worked as a district medical officer then atthe University of Oslo, and for the Oslo city health administration, International Organization for Migration, and WHO in Geneva, and now works in the Norwegian Directorate of Health.
In a recent article in Demographic Research, the global population size is modeled with alternative fertility rates (0.75 – 2.5) combined with maximum life expectancy of 90, 100 and 120 years. If global fertility in the long run converges to a level of 1.5 – which is slightly below the 2009 average level in the European Union of 1.59 – then, after peaking around the middle of the century, the world population would return to the current level of seven billion people by 2110. By the end of the 22nd century it would fall below three billion under the scenario of 100 years life expectancy in all parts of the world.
If, more dramatically, the global fertility rate approaches the figure currently seen in East Asia, below one, the population will be below four billion at the end of this century. The demographic transitions today happen fast, and the two-child norm is not necessarily the end-point of transition. Today already, sizeable populations exist where the voluntary chosen ideal family size is heavily concentrated around one child per woman, with total fertility rate as low as 0.6-0.8.
Figure 2: Global population scenarios: 2000-2300
Source: Basten, Lutz and Scherbov: Very long range population scenarios to 2300 and the implication of sustained low fertility