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“World population growth could slow from 2065 onwards”

Hervé Le Bras
Hervé Le Bras
Research director in demographics at EHESS and Emeritus research director at Ined

The Aus­tri­an demog­ra­ph­er Wolf­gang Lutz pre­dicts a decline in the world’s pop­u­la­tion from 2065 onwards, where­as peo­ple are more like­ly to speak of a “demo­graph­ic per­il” by 2050. What can we say about the long-term evo­lu­tion of the population?

If we look at the evo­lu­tion of the annu­al pop­u­la­tion growth rate, it peaks at 2.1% in 1975 (i.e., a dou­bling every 33 years), then decreas­es to 1% today and could be can­celled out by 2065, when the pop­u­la­tion would begin to decline. 

Nev­er­the­less, when mak­ing pre­dic­tions beyond 2050, past errors have taught us to han­dle fore­casts with cau­tion. For exam­ple, in 1994, the Unit­ed Nations Pop­u­la­tion Divi­sion pro­ject­ed 163 mil­lion Ira­ni­ans by 2050 and is now pro­ject­ing 103 mil­lion after drop­ping to 94 mil­lion in 2014. In the mean­time, fer­til­i­ty has dropped from 6.5 chil­dren per woman to 1.7, then back up to 1.9. The same is true for France, which in 1994 was pro­ject­ed to have 60 mil­lion inhab­i­tants in 2050 and now projects 74 mil­lion. The rise in the birth rate at the end of the 1990s was poor­ly antic­i­pat­ed, as was net migration.

The medi­an fore­cast of the Unit­ed Nations is for con­tin­u­ous growth until 2100 and a pop­u­la­tion of 11.2 bil­lion peo­ple by that date. Should we doubt this fore­cast in light of the work of Wolf­gang Lutz?

There are sev­er­al rea­sons to doubt it. The Unit­ed Nations pre­dicts a slow decline in fer­til­i­ty in intertrop­i­cal Africa (between the Sahara and the Zam­bezi), even though this area accounts for a quar­ter of the world’s pop­u­la­tion growth and will account for three quar­ters by 2050. For exam­ple, the Unit­ed Nations pre­dicts that Niger, the world’s fer­til­i­ty cham­pi­on, will drop from 7.3 chil­dren per woman to 4 in 2050 and 2.5 in 2100. How­ev­er, much faster declines have occurred in the recent past. Between 1985 and 2005, fer­til­i­ty was halved in South Africa, from 5 to 2.6 chil­dren per woman, and it fell from 6.5 to 1.9 in Iran over the same period.

Pro­jec­tion of the world pop­u­la­tion until 2100 © ONU

Sec­ond, the UN pre­dicts baby booms in sev­er­al coun­tries with very low fer­til­i­ty, such as South Korea (0.98) and Sin­ga­pore (1.14). When fer­til­i­ty is below 1.3 chil­dren per woman, the Unit­ed Nations sys­tem­at­i­cal­ly fore­casts an increase to 1.5 by 2050, then to 1.7 or 1.8 by 2100. Indeed, fer­til­i­ty rates are ris­ing again after sharp declines. We can cite the case of the for­mer East­ern bloc coun­tries, which expe­ri­enced a sharp drop in fer­til­i­ty linked to the decline in the age of first child (from 23 to 28). How­ev­er, once the tran­si­tion was com­plet­ed, there was a return to nor­mal and a slight increase, albeit mod­er­ate. In Poland, the num­ber of chil­dren per woman rose from 1.24 in 2004 to 1.41 in 2011 and in Hun­gary from 1.25 to 1.39 from 2011 to 2016. Then fer­til­i­ty fell back down. These mechan­i­cal effects are insuf­fi­cient to jus­ti­fy the UN projections.

Is fer­til­i­ty misjudged?

On the whole, the decline in fer­til­i­ty is fair­ly poor­ly antic­i­pat­ed. Two-thirds of the world’s pop­u­la­tion live in a coun­try where fer­til­i­ty is below two chil­dren per woman. In Latin Amer­i­ca, the coun­try – or region – with the high­est fer­til­i­ty is French Guyana! Brazil has gone from 6.5 chil­dren per woman to 1.7 in 40 years. 

Final­ly, the two most pop­u­lous coun­tries, Chi­na and India, are expe­ri­enc­ing a rapid decline in fer­til­i­ty. In India, it is already 2.3 chil­dren per woman and in 23 out of 36 states below 2.1. In Chi­na, the aban­don­ment of the one-child pol­i­cy in 2017 gen­er­at­ed a slight increase that has since ful­ly sub­sided. But again, the demo­graph­ic tran­si­tion has a lag effect. Chi­na, to use this exam­ple, will only expe­ri­ence a decline in pop­u­la­tion from 2032 onwards. 

Do you see oth­er rea­sons for over­es­ti­mat­ing pop­u­la­tion growth?

Yes, the decline in mor­tal­i­ty seems to be over­es­ti­mat­ed. This con­tributes to the demo­graph­ic boom because peo­ple are liv­ing longer. How­ev­er, over the past five years, the aver­age age of death has increased much more slow­ly in devel­oped coun­tries. Pos­si­ble caus­es include obe­si­ty, envi­ron­men­tal degra­da­tion, and inequal­i­ty. How­ev­er, the UN expects a gain of five years of life by 2030 in these coun­tries. This seems very optimistic. 

Pro­jec­tion of world pop­u­la­tion births and deaths to 2100 © ONU

What will the world pop­u­la­tion be in 2100?

It will not reach 11 bil­lion, but rather 10 bil­lion. We can say that the pop­u­la­tion explo­sion is almost over. The explo­sion of the 1990s and 2000s is behind us and the decline will come soon­er than we think.

What could be the con­se­quences of this demo­graph­ic decline?

I see two major soci­etal changes. The nec­es­sary delay in retire­ment in coun­tries that have a pen­sion sys­tem (to main­tain it), and the entry of women into the work­force in coun­tries where their par­tic­i­pa­tion rate is low. In both cas­es, this requires a change in men­tal­i­ty. We see this in France with retire­ment. The philoso­pher Mar­cel Gauchet talks about the “social­ist moment” of life: free time, mon­ey and no more boss! Many peo­ple do not want to give it up. 

As for health costs, they are real­ly con­cen­trat­ed in the last months of people’s lives. The decline in mor­tal­i­ty post­pones health costs more than it increas­es them, all oth­er things being equal.

Interview by Clément Boulle

Contributors

Hervé Le Bras

Hervé Le Bras

Research director in demographics at EHESS and Emeritus research director at Ined

Historian and demographer, Hervé Le Bras holds the "territories and topulations" chair at the FMSH's College of World Studies, Fellow of Churchill College (Cambridge). He has directed the Laboratoire de démographie historique (CNRS) and chaired the scientific council of the DATAR. He is the author of some sixty books, including Naissance de la mortalité (Gallimard) and The Nature of Demography (Princeton U. P.). He is also a graduate of the Ecole polytechnique (X63).