The Earth will be home to 8.8 billion people in 2100, two billion fewer than current UN projections, says new study.

More than 20 countries, including Italy, Japan, Poland, Portugal, South Korea, Spain and Thailand, will see their numbers diminish by at least half by the year 2100, according to projections in a major study.

China’s population will fall from 1.4 billion people today to 730 million in 80 years, said the study led by an international team of researchers, published in The Lancet on Wednesday.

The Earth will be home to 8.8 billion people in 2100, two billion fewer than current UN projections, the study said, foreseeing new global power alignments shaped by declining fertility rates and ageing populations.

By century’s end, 183 of 195 countries, barring an influx of immigrants, will have fallen below the replacement threshold needed to maintain population levels, it said.

Sub-Saharan Africa, meanwhile, will triple in size to some three billion people, with Nigeria alone expanding to almost 800 million in 2100, second only to India’s 1.1 billion.

‘Good news for the environment’

“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,” lead author Christopher Murray, director of the Institute for Health Metrics and Evaluation (IHME) at the University of Washington, told AFP news agency.

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

For high-income countries in this category, the best solutions for sustaining population levels and economic growth will be flexible immigration policies and social support for families who want children, the study concluded.

“However, in the face of declining population, there is a very real danger that some countries might consider policies that restrict access to reproductive health services, with potentially devastating consequences,” Murray cautioned.

“It is imperative that women’s freedom and rights are at the top of every government’s development agenda.”

Social services and healthcare systems will need to be overhauled to accommodate much older populations.

As fertility falls and life expectancy increases worldwide, the number of children under five is forecast to decline by more than 40 percent, from 681 million in 2017 to 401 million in 2100, the study found.

At the other end of the spectrum, 2.37 billion people, more than a quarter of the global population, will be over 65 years of age by then. The number of those over 80 will balloon from about 140 million today to 866 million.

Sharp declines in the number and proportion of the working-age population will also pose huge challenges in many countries.

“Societies will struggle to grow with fewer workers and taxpayers,” said Stein Emil Vollset, a professor at IHME.

The number of people of working age in China, for example, will plummet from about 950 million today to just over 350 million by the end of the century – a 62-percent drop.

The world’s population grew from 2.5 billion in 1950 to 7.7 billion in 2020

The decline in India is projected to be less steep, from 762 to 578 million.

In Nigeria, by contrast, the active labour force will expand from 86 million today to more than 450 million in 2100.

RELATED ARTICLESMORE FROM AUTHOR