Modelling suggests the world population will peak in 2064 at around 9.7 billion.

A new study finds that improvements in access to modern contraception and the education of girls and women are generating widespread, sustained declines in fertility.

Modelling based on data from the Global Burden of Disease Study 2017 finds and world population will likely peak in 2064 at around 9.7 billion, and then decline to about 8.8 billion by 2100 - about 2 billion lower than some previous estimates.

The estimates are that by 2100, 183 of 195 countries will have total fertility rates (TFR), which represent the average number of children a woman delivers over her lifetime, below replacement level of 2.1 births per woman.

This means that in these countries, populations will decline unless low fertility is compensated by immigration.

The forecasts are in contrast to projections of ‘continuing global growth’ by the United Nations Population Division.

They also highlight the huge challenges to economic growth of a shrinking workforce, the high burden on health and social support systems of an ageing population, and the impact on global power linked to shifts in world population.

It also predicts huge shifts in the global age structure, with an estimated 2.37 billion individuals over 65 years globally in 2100, compared with 1.7 billion under 20 years, underscoring the need for liberal immigration policies in countries with significantly declining working age populations.

“Continued global population growth through the century is no longer the most likely trajectory for the world’s population”, says Dr Christopher Murray, who led the research.

“This study provides governments of all countries an opportunity to start rethinking their policies on migration, workforces and economic development to address the challenges presented by demographic change.”

First author of the paper, Professor Stein Emil Vollset, says; “The societal, economic, and geopolitical power implications of our predictions are substantial”.

“In particular, our findings suggest that the decline in the numbers of working-age adults alone will reduce GDP growth rates that could result in major shifts in global economic power by the century’s end.

“Responding to population decline is likely to become an overriding policy concern in many nations, but must not compromise efforts to enhance women’s reproductive health or progress on women’s rights.”

The study is accessible here.