The planet’s population will get to 10.4 billion – then drop. Here’s when we reach peak human

India overtook China as the world’s most populous nation in 2023 but far bigger population shifts are transforming the world. Where will all the people be in 2100?

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It’s 2050 and the world is home to 10 billion people. India remains the population colossus with a head count of 1.67 billion, more than China and the United States combined. Africa is the population juggernaut with a quarter of the world’s people and its largest workforce. Nations in Europe and Asia are still ageing and shrinking. Australia has managed to hold its own, barely moving in the rankings as other nations shuffle around it.

Such forecasts might seem abstract, but population counts: it shapes cultures, affects economies and influences political clout. That’s why it’s a perennial source of public anxiety, whether it’s going up or down.

There have long been fears about too many people on the planet. Unchecked population leads to poverty, misery and war, if you follow the line of thought of 18th-century British economist Thomas Malthus. “Malthusian” pessimism regularly surfaces, particularly in the era of climate change.

On the other hand, fears about not enough people are perennial too, now keenly felt by an increasing number of nations as low birth rates provoke warnings of a “population winter”. In Hungary, radical measures are afoot to get women having babies.

In Britain, where birth rates have dropped to their lowest level in two decades, demographer Paul Morland has controversially called for a tax on those who don’t have offspring. “This may seem unfair on those who can’t or won’t have children,” he wrote in The Sunday Times. “But it recognises that we all rely on there being a next generation and that everyone should contribute to the cost of creating that generation.”

So how will the world’s population change this century? Where will all the people be? And how will this affect Australia?

Lagos is set to become one of the world’s most populous cities in the world’s third-most-populous nation, Nigeria, by 2100.Credit: Getty Images

What’s shaping the world’s population?

Every two years the United Nations Population Division updates its projections. The first report, in 1951, put the population of the Earth “in round numbers” at 2.4 billion. The head count passed 8 billion in November 2022.

Since the mid-1970s, the world has been adding an extra billion people roughly every 12 years. But if you reckon the world’s population is on a never-ending upward spiral, think again. The rate of population growth peaked in the early 1960s; in 2020, it dipped under 1 per cent for the first time since 1950. We will reach “peak human” in 2086, according to the UN, when the world’s population hits 10.4 billion. Population growth is expected to have been easing to 0.5 per cent a year by 2050 and will sink into the negative by 2100.

This chart, from the year 1700, tells part of the story.

The trend is like a slowing vehicle, says associate professor Udoy Saikia. “I tell my students that, ‘Yes, we are still driving the car forward but as we move forward, the speed will be less and less and less’,” says Saikia, a population expert at Flinders University.

Other forecasts differ, although mostly over timing rather than the overall trend. Modelling by the Institute for Health Metrics and Evaluation (IHME) at Washington University, for example, forecasts the world’s population to top out at 9.7 billion in 2064 then drop. In that study, published by The Lancet in 2020, the world’s population will be 8.8 billion in 2100, almost 2 billion fewer than the UN’s central projection.

Saikia says “considerable” declines in fertility rates recently, especially in huge nations such as China, India and Bangladesh, make it plausible the world’s population will peak earlier than the UN has predicted.

When that happens, more people will be dying than are being born.

The fertility rate measures the average number of children a woman can be expected to have during her lifetime. Since 1950 the global rate has fallen from around five to 2.3. By 2050, it is projected to reach 2.1. It so happens that a fertility rate of 2.1 is deemed to be the “replacement level” at which the number of births and deaths are roughly in balance, ensuring a stable population (excluding migration). Then the rate is expected to drop further.

Already, the share of nations with very low fertility rates has jumped. Most people in the world, including in its 15 biggest economies (measured in US dollars), live in nations with a fertility rate below the 2.1 replacement level, including China and India. In Australia in 1970, the rate was about three children per woman. Now it’s 1.63.

More people will be dying than are being born. Since 1950, the global fertility rate has fallen from five children per woman to 2.3.

Fertility rates have fallen even in places associated with rapid population growth, such as Asian megacities. “Take a city like Kolkata in India, for example,” says Saikia. “There the fertility rate is now much lower even than in Australia.”

Some low-income countries, especially in Africa, still have relatively high fertility rates. The West African nation of Niger topped the list in 2019 with 6.9 followed by Somalia (6.5) and Chad (6.4). But even in those nations, rates are trending lower. In Botswana, the fertility rate has dropped to around 2.8 children per woman. In Namibia, it’s 3.3; in Zimbabwe 3.5, according to the World Bank. All three nations had a fertility rate hovering around 7 in 1970.

Here’s how the trend looks, with births (green) dipping below deaths (red).

Macquarie University demographer Professor Nick Parr warns two big unknowns cloud the longer-term outlook. The first is how quickly fertility rates decline in sub-Saharan Africa – the change has been slow and uneven, and past predictions of decreases have been proven wrong.

The second of Parr’s unknowns stems from the end of China’s one-child policy, which lasted from 1980 until 2016. “The United Nations projections assume quite a substantial recovery in the birth rates for China,” says Parr. “So far, there hasn’t really been a recovery despite the move from a one-child policy to a two-child policy and now to a three-child policy.”

Meanwhile, people are living longer. In 1900, a baby could expect to make it to 32, on average globally. The figure was 72.8 years in 2019 and the UN predicts it will get to 77 by 2050. Longer life spans and fewer babies means the world’s population is ageing. Saikia says that by 2050, there will be twice as many people aged over 65 than those aged under five. The median age of a person on Earth is 31.5 years. That will climb to 42.3 years by 2100, UN forecasts show. And there are big differences in the age structure of world regions. The median age in Europe is now 42.5 years now while in sub-Saharan Africa it is 18.7 years (more on that later).

Delhi will have the most people of any city by 2030, overtaking Tokyo. Credit: Getty Images

So, which places will have the most people by 2100?

More than half of the world’s people live in cities. By 2050, it’s expected to be more than two-thirds. UN projections for specific city populations extend only as far as 2030, but they signal longer-term trends. In 1970, New York, Los Angeles, London and Paris all ranked among the world’s 10 biggest cities; in 2023, no city from North America or Europe is on that list.

Tokyo will be overtaken by India’s capital, Delhi, by 2030. Another Indian city, the home of Bollywood, seaside Mumbai, is in the top 10 in 2030 too. China has two entrants: Shanghai and Beijing. The newest top 10 entry by 2030 will be Kinshasa in the Congo. (Nigeria’s Lagos ranks 11.)

Here are projections for the top 10 most populous cities in 2030.

The UN population projections for nations extend to the end of the century. This year, India overtook China as the most populous nation. India will still have the most people in 2050 when the global headcount is forecast to reach 9.7 billion. More than half of the projected population increase between now and that time will be concentrated in just eight countries: India, the Democratic Republic of the Congo, Egypt, Ethiopia, Nigeria, Pakistan, the Philippines and the United Republic of Tanzania.

Five of those countries are in what is known as sub-Saharan Africa, which accounts for 46 of Africa’s 55 countries. By 2050, remember, it will be home to a quarter of the world’s people, up from 17 per cent now. Its largest economy, Nigeria, is projected to become the third most populous country by 2050. The former British colony is rich in natural resources, including minerals such as lithium, cobalt and nickel used in electric cars. Its capital, Lagos, a sprawling megacity renowned for its music and traffic jams, is forecast to have more than 20 million residents by the end of this decade alone.

“Africa is entering a period of truly staggering change,” Edward Paice, the director of the Africa Research Institute in London, told The New York Times. By 2100, sub-Saharan Africa is forecast to be the world’s most populated region with more than 3 billion people. Europe, North America, South America and East and South-East Asia are all expected to have fewer people than they do now.

Watch the changes in this animated chart.

By the 2040s, Africa will account for two out of every five children born on the planet. For some nations in the region having a large, relatively youthful population will likely translate to more economic and political clout on the world stage. Yet more people can mean more problems too. Nearly two-thirds of Nigeria’s 213 million people live on less than $3 a day.

In our neighbourhood, it’s Indonesia that’s exploding: projected to reach 300 million – from today’s 277 million – by 2100. Which is one reason its president, Joko Widodo, wants to relocate Indonesia’s capital from congested and flood-prone Jakarta (population 11.2 million) to the new-build city of Nusantara in East Kalimantan.

Here are the changes in a different format.

And Australia? The UN forecasts we will have the 58th largest population in 2100 with 38.1 million people, a little lower than what the federal government forecast in its 2023 intergenerational report.

Why aren’t people having babies?

One reason is the uptake in education, particularly for girls. In Angola, according to The Economist, women with tertiary education have an average of 2.3 children, compared to 7.8 children born to women without any schooling.

Wealth must also play a role, as the richest nations have the lowest fertility rates, but its effect is a little more complicated. Being truly wealthy means you can afford more children and the support network necessary to raise them in (your) comfort (ask Elon Musk, father of 11). Yet being relatively wealthy but still struggling to keep up with the Joneses can make having children a lower priority in cities such as Seoul or Tokyo (or Melbourne or Sydney, for that matter) where real estate is prohibitively expensive for many.

It’s no myth that television soap operas, called novelas, have played a significant role in dropping Brazil’s fertility rate.

The availability of contraception is another clear factor. Other reasons tend to be more particular to each nation.

It’s no myth, for example, that television soap operas, called novelas, have played a significant role in dropping Brazil’s fertility rate from around six children per woman in 1960 to 1.6 in 2021. A 2012 paper that cross-referenced the regional availability of a particular format of soap opera with birth rates and children’s naming patterns (named after characters on the shows) found these viewing habits led to “significantly lower fertility”. The authors suggested this was largely because the shows’ main female characters were typically childless or had only one child.

Demographic experts in India’s Kolkata, meanwhile, have attributed the drop in the fertility rate there, more prosaically, to the widespread adoption of contraception, financial pressures and a trend away from traditionally preferring sons over daughters. (The population is still vast, a shade over 15 million.)

Hungary’s president, Viktor Oban, blames climate science – and fear of armageddon – for at least some of his country’s low fertility rate, which remains stable at a shade over 1.5 children per woman. This is despite some aggressive government incentives to procreate. such as low-interest loans and income tax exemptions for people with four or more children.

South Korean high-school students cheer for their senior classmates, among the half a million taking the rigorous College Scholastic Ability Test in Seoul 2019.Credit: Getty Images

South Korea has one of the lowest fertility rates. The IHME predicts it will be among 23 countries where the population will halve between 2017 and 2100. Others include Japan, Thailand, Italy and Spain. Another 34 countries are forecast to have population falls of between a quarter and half, including China (down 48 per cent).

So concerned is Seoul’s government, it sent a delegation to study the improbable community of Nagi, on Japan’s Honshu island, where local authorities have bucked the country’s overall birth rate trend with innovative incentives. Childcare is inexpensive, parents get kickbacks for every year their child remains in high school and a job-matching system helps part-time workers balance work and family life.

But social attitudes are harder to shift. In South Korea, experts point to a rebellion against traditional gender norms and a growing divide between men and women, exacerbated by a male anti-feminist campaign. The pushback against this began with 2018’s “escape the corset” movement, which saw Korean women cut their hair short and go barefaced, then escalated into the “four nos”: bihon, the refusal of heterosexual marriage; bichulsan, refusal of childbirth; biyeonae, saying no to dating; and bisekseu, the rejection of heterosexual sexual relationships.

Other disincentives in South Korea include a hyper-competitive education system and some decidedly family-unfriendly laws – restaurants, museums and even the national library can bar children from entering. A survey of 15,000 people aged 19 to 34 this year found barely half of women intended to have children while 70 per cent of men said they would be willing. “The birth strike is women’s revenge on a society that puts impossible burdens on us and doesn’t respect us,” Seoul office worker Jiny Kim, 30, told The New York Times.

The UN says more family-friendly policies, including more generous parental leave and affordable childcare, will be needed worldwide to build “demographic resilience.” Italy, whose fertility rate had dropped to 1.24 by 2020, recently increased benefits, particularly for families with more than three children, and extended maternity leave.

Yet, the evidence that such policies work is mixed. Poland introduced a monthly family benefit in 2016 to encourage families to try for two or more children but has yet to see an increase in the number of babies born, reports The Economist. Singapore offers paid maternity leave, childcare subsidies, tax relief and rebates, one-time cash gifts, and grants for companies that implement flexible work arrangements, yet its fertility rate still dropped to 1.12 in 2022. Many young people are deferring dating to focus on career, writes Poh Lin Tan of the National University of Singapore, and most married couples stop at one or two children, “owing to high education-related expenses and the desire to invest more in each child”.

As the problem becomes more acute, the IHME study warns, some nations might resort to coercive policies. “A very real danger exists that, in the face of declining population, some states might consider adopting policies that restrict female reproductive health rights and access to services,” the study warned. “Low fertility in these settings might become a major challenge to progress for females’ freedom and rights.”

Residents of an aged-care facility meet a remote-controlled “humanoid” robot in Natori, Japan.Credit: Getty Images

Aren’t fewer people good for the planet?

Economist Thomas Robert Malthus made some revolutionary predictions in his 1798 treatise An Essay on the Principle of Population, not least that human beings would reproduce exponentially to the point of starvation. The world’s population at that time was poised to reach its first billion. And, yes, if it had grown as Malthus had warned, we would be over-run today. “The power of population is so superior to the power of the Earth to produce subsistence for man, that premature death must in some shape or other visit the human race,” Malthus foresaw. Yet, as the rather less intellectual but possibly more insightful Yogi Berra intoned, “It’s hard to make predictions, especially about the future.”

A decline in global population is potentially good news for the environment and climate change. Fewer people on the planet could lower carbon emissions, reduce competition for natural resources and ease pressures on global food supplies.

But while size is one matter, the dramatic shift in the age structure in many nations will have other sweeping, and often negative, consequences. The size of a nation’s working-age population is a key economic driver (along with productivity growth, fuelled by innovation, and workforce participation). With far more elderly people and a shrinking pool of workers and taxpayers, some nations will struggle to generate the revenue needed to fund aged care, social security and healthcare. The UN, declaring ageing one of the most significant world trends of the 21st century, has called for governments to address the needs and interests of older people.

Ageing is the “population bomb”, write David Bloom and Leo Zucker for the International Monetary Fund. “The potential consequences of inaction are dramatic: a dwindling workforce straining to support burgeoning numbers of retirees, a concomitant explosion of age-related morbidity and associated healthcare costs, and a declining quality of life among older people for lack of human, financial and institutional resources.”

Fewer than 3 per cent of Nigerians were over 65 in 2021; in Japan, it was a quarter of people. Japan offers an extreme snapshot: economic stagnation, emptied-out villages and workers staying on the job into their 70s. “We are approaching an era of acute labour shortages in much of the world – and robots are not yet ready to come to our assistance,” demographer Paul Morland told this masthead last year.

Eligibility for the old-age pension has already been creeping up in many countries as governments attempt to lift workforce participation and limit the costs of supporting a growing cohort of retirees – which may be fiscally sensible but is rarely popular. When French leader Emmanuel Macron pushed through a change to pension eligibility from 62 to 64 (for those born after 1967) this year he triggered widespread violent protests. In Australia, workforce participation by those aged 65 and over has risen steadily during the past two decades, making that group an increasingly important contributor to the economy.

Australia will keep its place in the world population rankings by 2100 even as other nations shift around it.Credit: Tanya Lake

What do these trends mean for Australia?

Debates about global population trends are likely to be radically different in the second half of this century, says Saikia. “When our grandchildren become the policymakers, they are likely to be talking about how to increase population rather than getting worried about a rising population,” he says.

Saikia predicts many nations will be forced to rely more on overseas migration to stave off the damaging effects of a population decline. “Migration sending countries will play a vital future role in the economies of other countries, especially developed countries including Australia,” he says.

Since the 1970s, Australia’s fertility rate has been below the 2.1 replacement level, but our population has continued to grow at a steady rate thanks to strong migration. We now rank the world’s 55th most populated country.

‘Nations that sustain their working-age populations over the long term through migration would fare well.’

Net overseas migration has accounted for more than 60 per cent of Australia’s population growth during the past decade, but that is forecast to reach 75 per cent by the 2060s. The federal government’s 2023 intergenerational report projected the national head count to rise from 26.5 million to 40.5 million by 2063, an increase of 53 per cent.

The IHME study says Australia’s liberal migration policies and ability to attract new arrivals will allow the nation to maintain a relatively stable working-age population and “various economic, social, and geopolitical benefits” that come with it throughout this century. “Nations that sustain their working-age populations over the long term through migration, such as Canada, Australia, and the USA, would fare well,” the report says.

It forecasts Australia to climb the global economic rankings as a result. In 2017, Australia was ranked the world’s 12th-largest economy (when measured in US dollars), says the IHME paper, which forecasts it to rise to 11th largest in 2050 and eighth largest in 2100.

Immigration policy is always fiercely contested, a fact underscored most recently by the political combat that has flared in late 2023. A temporary migration boom following the COVID-19 pandemic stoked public anxiety about housing supply shortages and pressures on infrastructure and essential services.

In December, the Albanese Government announced a sweeping overhaul to bring “migration back down to sustainable, normal levels” including a lower intake and more stringent rules for overseas students. “Our mission is clear,” said Home Affairs Minister Clare O’Neil, “to build a migration system that earns the trust and confidence of our citizens and secures a safe and prosperous future for every Australian.”

Striking the right balance on migration will challenge Australia’s political leaders as the dynamics of the global population shift, even if our numbers are a small part of the planet’s story. We account for about 0.33 per cent of the world’s people.

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