• Nearly 11 billion people will be on Earth by the end of the century, the United Nations says.
  • But a new study suggests that’s no longer the most likely scenario and forecasts a peak just after mid-century and then a decline.
  • The University of Washington says the world population will fall in the last third of this century to 8.8 billion in 2100.
  • Understanding how populations could evolve matters because it affects the strategies put in place by global governments and industries.

Overpopulation is a concept that’s hovered over the Earth’s future for some time.

It has inspired many works, including Stephen Emmott’s 10 Billion, which outlines a future of food shortages, energy wars and civil conflict.

But what if studies invoking concerns about a fast-rising world population were wrong? That could be the case, according to The University of Washington’s Institute for Health Metrics and Evaluation, which challenges the assumptions behind predictions for continued growth and says a declining and ageing population will be key future challenges.

That sets it at odds with the United Nations which predicts that the global population will continue to grow, albeit at a slower pace, and will reach 10.9 billion in 2100, up from around 7.7 billion people in 2019.

Why do these predictions matter?

Understanding how populations could evolve matters because future population sizes underpin future strategies for governments and industries around the world; they need to plan for key investments in infrastructure or goals for international development and carbon emission reductions. A decline, instead of an increase, would have many implications.

“Our forecasts for a shrinking world population have positive implications for the environment, climate change, and food production,” the researchers, led by Professor Stein Emil Vollset, wrote. “But possible negative implications for labour forces, economic growth, and social support systems.”

How do the world population predictions vary?

Population boom and bust?
The UN predicts a much larger boom in population than the University of Washington.
Image: Statista

The world population may peak in 2064 at 9.7 billion and then decline to around 8.8 billion by 2100, the University of Washington researchers wrote in The Lancet.

Total world population from 2010 to 2020.
In 2020, the world’s population was recorded at 7.75 billion and growing.
Image: Statista
Future of Work

What is the World Economic Forum doing about including older people in the workforce?

There is a global myth that productivity declines as workers age. In fact, including older workers is an untapped source for growth.

The world has entered a new phase of demographic development where people are living longer and healthier lives. As government pension schemes are generally ill-equipped to manage this change, insurers and other private-sector stakeholders have an opportunity to step in.

The World Economic Forum, along with the Organisation for Economic Co-operation and Development (OECD) and AARP, have created a learning collaborative with over 50 global employers including AIG, Allianz, Aegon, Home Instead, Invesco and Mercer. These companies represent over two million employees and $1 trillion in annual revenue.

Learn more in our impact story.

The UN’s prediction of 10.9 billion by 2100 is based, at least in part, on “the unprecedented ageing of the world’s population”, as well as “rapid population growth driven by high fertility” in some countries and regions.

Whereas, the University of Washington’s researchers argue that a population decline will be linked to the attainment of developmental goals, for example the education of women and girls and their access to contraception.

“The different outcomes reflect the uncertainty in making projections over such a long time period,” says Leontine Alkema, a statistical modeller at the University of Massachusetts Amherst, discussing discrepancies in population data for a Nature article.

“It’s kind of an impossible exercise and so we do the best we can and it’s good that different groups use different approaches.”