The world population will decline in the second half of the century to reach 8.8 billion in 2100, 2 billion less than the projections of the UN, according to a study published Wednesday, July 15 in The Lancet.

This is "good news for the environment (less pressure on food production systems and less CO2 emissions)", said AFP Christopher Murray, director of the respected Institute for Health Metrics and Evaluation (IHME ) in Seattle, who conducted this study.

But "the inversion of the age pyramid will have profound and negative consequences on the economy and the organization of families, communities and societies", he tempers. Even if these projections are not "set in stone" and that changes in policies could modify the trajectories of the different countries.

Reduced fertility rate

According to the last UN report on the world population, the Earth should carry 9.7 billion inhabitants in 2050 and 10.9 billion in 2100, against 7.7 billion currently. But the new study questions this continued growth throughout the 21st century.

Researchers from the IHME, an organization funded by the Bill and Melinda Gates foundation that is a reference for its global studies in public health, predict a peak as early as 2064, at 9.7 billion people, before declining to 8.8 billion in 2100

This decline will be largely linked to the development of girls' education and access to contraception, which will lower the fertility rate to 1.66 children per woman in 2100 compared to 2.37 today, according to l 'study. A fall in fertility much faster than the UN predicts. In 183 countries out of the 195 studied, this rate would fall by 2100 to under 2.1 children per woman, making it possible to maintain the population without any migratory contribution.

Redistribution of cards

But demographic trends, also including mortality and migration, will vary by region and country, according to the researchers. They anticipate a possible redistribution of economic and geopolitical maps, even if the power of a State is not necessarily reduced to the sole size of its population.

Thus, China could lose almost half of its inhabitants (1.4 billion today, 730 million in 2100), with a decline in the number of people of working age which will "hamper" its economic growth. The United States, which will soon lose its place as the world's leading economy, could thus overtake China by the end of the century, if immigration continues to offset declining fertility, according to the study.

Asia and Europe are expected to lose residents. They are home to a large part of the 23 countries which should see their population reduced by at least half: Japan (128 to 60 million), Thailand (71 to 35), Spain (46 to 23), Italy (61 to 31), Portugal ( 11 to 4.5), South Korea (53 to 27). Even if some countries like France escape it (65 to 67 million).

Nigeria driving force in Africa

In contrast, sub-Saharan Africa could see its population triple (1 to 3 billion), driven in particular by Nigeria (206 to 790 million inhabitants), which would become in 2100 the second most populous country in the world behind India but before China.

"It will truly be a new world, a world we should prepare for today," commented Lancet editor Richard Horton.

In this world where the working age population has decreased but where the over 80s are six times more numerous (141 to 866 million), it would be necessary to "reassess the current structure of social assistance systems and health services" , insists Christopher Murray.

Womens rights

"The response to this decline in populations is likely to become one of the major political concerns in many countries," said in a statement his colleague Stein Emil Vollset. "But this should not compromise efforts to improve women's reproductive health or the advancement of women's rights," he insists.

To modify the demographic trajectory, they invoke conversely "social policies" to help women to work while having the number of children they want. But also "liberal immigration policies". "We believe that later in the century, countries that need migrant workers will have to compete to attract these migrants", who should come mainly from sub-Saharan Africa and the Arab world, says Christophe Murray.

With AFP

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