World population to peak at 9.7bn by 2064 before entering period of decline, study suggests

Failing fertility rates could see population of 23 countries halved by 2100, say researchers

Current world population is around 7.8 billion (Getty Images/iStockphoto)

Earth’s population is set to peak at 9.7bn in 2064 before entering a period of natural decline that could see fundamental changes to the way societies are organised, a major new study suggests.

Falling fertility rates across much of the world mean that 183 of 195 countries could have shrinking populations by the end of the century, according to research published in the Lancet Journal.

Ageing populations and fewer babies being born could lead to more than 20 countries – including Spain, Italy and Japan – seeing their numbers plunge by up to 50 per cent.

Researchers at the University of Washington’s Institute for Health Metrics and Evaluation predict the world’s population to be 8.8bn by 2100 – almost 2bn billion fewer than projections published in a 2019 United Nations report.

Countries’ populations are decreasing because their fertility rate – the average number of children a woman gives birth to – has fallen below 2.1. Anything below this figure and the population begins to shrink.

In 1950, women were having an average of 4.7 children in their lifetime.

The study showed that the global fertility rate dropped almost 50 per cent to 2.4 in 2017 and is projected to fall below 1.7 by 2100.

Greater access to contraception, more women in the workplace, improved education and couples choosing to have fewer children are all reasons why populations are decreasing in size, the researchers said.

Sub-Saharan Africa and parts of Asia will see population growth as the century progresses. Nigeria could become the world’s second most populous country by 2100, with 791 million people.

China – currently the world’s most populous country – will see its number of people drop from 1.4bn to 732 million and be replaced by India.

Lead author Christopher Murray at the University of Washington, said: “These forecasts suggest good news for the environment, with less stress on food production systems and lower carbon emissions, as well as significant economic opportunity for parts of sub-Saharan Africa.

“However, most countries outside of Africa will see shrinking workforces and inverting population pyramids, which will have profound negative consequences for the economy.”

In the past, many countries in the west – including the UK – have used immigration to compensate for falling population numbers.

Professor Stein Vollset, one of the study’s lead authors, said: “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.”

Professor Ibrahaim Abubakar, of University College London, said that going forward, migration will become a “necessity” for countries’ economic prosperity.

“If these predictions are even half accurate, migration will become a necessity for all nations and not an option,” he said. “To be successful we need a fundamental rethink of global politics.

“The distribution of working-age populations will be crucial to whether humanity prospers or withers.”