The US population will grow until 2062, then shrink – alongside 182 other countries around the world – to 336 million by 2100, a new study predicts.
Fertility rates in the US and abroad have been declining and are expected to continue to do so for decades to come, driving the number of people in many nations down for the next 80 years, according to the new research from the University of Washington’s Institute of Health Metrics and Evaluation (IHME).
Women are having fewer children as more widespread gender equality allows them to pursue educations, and careers and improved access to contraception – shifts that delay the age at which women start to have children and the limiting the number of kids they ultimately give birth to.
By 2100, the authors of the new study, published in The Lancet, predict the average American woman will have just 1.5 children, 17.7 percent lower than 2017’s fertility rate of 1.8 children per woman. These falling birth rates are expected to drive the US population down from its 2062 peak of 364 million to 336 million by 2100.
Coupled with aging populations, declining fertility could shrink the populations of 23 countries – including Japan, Thailand, Italy and Spain.
The result will be a global population that shrinks from a peak of 9.7 billion to 8.8billion by 2100.
Meanwhile, the American life expectancy is continuing to extend, according to new research from Harvard University’s TH Chan School of Public Health, meaning that more people will live longer past the years when they contribute to the economy or to population growth.
But the UW scientists caution against putting societal pressure on women to have more children, which could offset the important public health, educational and economic benefits women have gained by delayed having children.
Instead, they say that the US, as well as other nations, will need to lean on immigration to replace the population, a key factor to keep economies stable or growing – but one that may face resistance in the US, where the political climate has increasingly turned against liberal immigration policies.
The US is among the countries (in purple, dark blue and dark green) that already have birth rates that are too low for the population to stay the same size or to grow, according to the study. Once the largest generations start to die off in those nations the populations will begin to shrink
The US has a population of about 331 million people, accounting for about 4.2 percent of the 7.8 billion people on Earth.
In order for the global population to be replaced – meaning the number of people would remain the same over time – each woman in the world would have to have 2.1 children.
Already, the US is well below that, with 1.77 births per women, as of 2017 (the most recent year for which there is complete data).
Globally, the birth rate is about 2.4 births per woman – enough to continue to continue to replace the population, but by a fairly slim margin that the IHME team expects to fade over over the next 50 years.
Earth’s population will peak in 44 years at around 9.7billion before it starts to shrink again, according to scientists who predict Nigeria will eventually be home to more people than China.
After 2064 the total number of people will start to fall because of a decline in the number of children people are having, dropping by 900 million to 8.8 billion by 2100.
Populations will only grow or stay stable if women have an average of 2.1 children each — but better education and contraception will stop this in future because women will be more able to work instead of staying at home as mothers and wives, experts say.
Many countries already have lower birth rates than are necessary to sustain population sizes, including most of Europe, Russia, Canada and the US, Brazil, China and Australia. In the coming decades, older citizens in these countries will start to die at a faster rate than they are replaced and the populations will shrink.
Some countries, including Japan, Spain and Thailand will see their communities shrink by a staggering 50 per cent or more, the University of Washington researchers predicted.
Nigeria is set to become one of the largest, wealthiest countries in the world by the end of this century, while India, China, USA, Pakistan and the Democratic Republic of the Congo will have the other largest populations
As populations in the West shrink faster than they will in Africa and Asia — it will take another 80 years or more for birth rates to drop below sustaining levels in some slower-developing countries — a global power shift will emerge.
Nigeria is set to become one of the largest, wealthiest countries in the world by the end of this century, the team believe. The US will remain the top global power except for a period in around 30 years’ time when China will succeed it before dropping down again.
India will be the world’s most populated country in 2100, the study says, with 1.09billion people — it currently has 1.3bn, second only to China (1.4bn). It will be followed by Nigeria (791m), China (732m), the US (336m), Pakistan (248m) and the Democratic Republic of the Congo (246m) in Africa.
The population of the UK (currently 66m) will peak in 2063 at 75million before falling back to 71.5million by the turn of the century. In the US (333m) the peak will be at 363million a year earlier, in 2062, before it drops to 336million.
And the economies of Indonesia, Turkey will make inroads to become two of the 12 most powerful nations by 2100 as Brazil and Russia slip down the global rankings.
The research was done by a team of 24 scientists led by Dr Christopher Murray and Professor Stein Vollset from the University of Washington in Seattle. The study was published in UK medical journal The Lancet.
Dr Murray said: ‘Continued global population growth through the century is no longer the most likely trajectory for the world’s population.’
The scientists who did the study said birth rates are expected to fall globally as more and more countries become modernised and traditional roles of women as mothers and homemakers fade away.
WHICH WILL BE THE WORLD’S TOP ECONOMIES IN 2100?
The University of Washington study predicted many of the world’s top economies will remain powerful over the next 80 years but there will be some reshuffling in the ranks.
These are their predictions, based on gross domestic product (GDP):
Rank in 2100
Rank in 2017
Greater availability and affordability of contraception in countries that currently have poor healthcare will mean that unplanned children will become less common and not just a consequence of sex.
Better education for girls, improving women’s rights and employment opportunities will also mean more women have full schooling and careers, making them less likely to have large families.
This is projected to lead to a drop in the fertility rate of the world’s population, from an average of 2.37 children per woman — 237 children from every 100 women — to 1.66, or 166 children for every 100 women.
The fertility rate must be 2 for a population to remain stable and 2.1 for it to increase, the researchers said. To keep a community the same size a mother must, on average, not only replace herself but also the baby’s father.
It could fall to as low as 1.17 in Poland, the study claimed, and to 1.2 in Spain.
A total of 23 countries are predicted to see their populations shrink by a staggering 50 per cent or more. They are: Latvia, El Salvador, Puerto Rico, Jamaica, United Arab Emirates, Bulgaria, Croatia, Ukraine, Cuba, Romania, Poland, Andorra, Moldova, Saint Vincent and the Grenadines, Bosnia and Herzegovina, Portugal, Taiwan, Japan, Serbia, Slovakia, Sri Lanka, Thailand and Spain.
However, the scientists were adamant that fears about shrinking, ageing populations and the effects they might have on the economy must not lead to a slowdown in the march for women’s rights.
Professor Vollset said: ‘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.’
Dr Murray and colleagues said their work goes against the United Nations, which projects the population of the world will continue growing for the rest of the century.
But they acknowledge that the global population is likely to explode in the next 40 years, rising by more than two billion people. Much of this growth will be in sub-Saharan Africa, where birth rates are already high.
The Lancet study predicted the population of sub-Saharan Africa — which includes Nigeria, Democratic Republic of Congo and Kenya — will triple between now and 2100, from 1.03billion in 2017 to 3.07billion in 80 years’ time as health improvements bring the continent’s death rate down.
Sub-Saharan Africa and North Africa and the Middle East will be the only regions where the populations are higher in 2100 than they were in 2017, the study said (left). In sub-Saharan Africa the population is expected to triple in that time. Niger and Chad (right), both in Africa, will see their populations soar in the next 80 years, increasing more than seven-fold, the scientists said
The economies of Indonesia, Turkey will make inroads to become two of the 12 most powerful nations by 2100 as Brazil and Russia slip down the global rankings
North Africa and the Middle East is the only other region that will have a bigger population in 2100 than it does now, the researchers said, with the number of people there rising from 600million to 978million.
MIGRATION ‘WILL BE NECESSARY FOR ECONOMIES TO SURVIVE’
Many wealthy European and Asian countries will see their populations shrink dramatically over the next 80 years, the Lancet study claims.
And low birth rates and improved survival will mean their average ages increase, with over-80s expected to outnumber under-fives by two to one around the world by 2100.
One impact of this will be drastically reduced workforces in some countries such as Japan, Italy and Spain, which are forecast to see populations more than halve.
In a bid to boost the number of people working in a country and keep its economy healthy, migration and international co-operation may become a necessity.
Professor Ibrahim Abubakar, from University College London, was not involved in the University of Washington study but said in a commentary: ‘Ultimately, if Murray and colleagues’ predictions are even half accurate, migration will become a necessity for all nations and not an option…
‘The choice that we face is whether we improve health and wealth by allowing planned population movement or if we end up with an underclass of imported labour and unstable societies.
‘The Anthropocene has created many challenges such as climate change and greater global migration. The distribution of working-age populations will be crucial to whether humanity prospers or withers.’
He added: ‘Nations would need to cooperate at levels that have eluded us to date to strategically support and fund the development of excess skilled human capital in countries that are a source of migrants.
‘The projected changes in the sizes of national economies and the consequent change in military power might force these discussions.’
For many countries in other parts of Asia and in Europe, populations will shrink because birth rates are already low. In some countries populations will drop by more than half.
In Japan the researchers estimated the population would fall from around 128million in 2017 to 60million in 2100 — a fall of 53 per cent.
In Thailand it is projected to drop from 71m to 35m (51 per cent); in Spain from 46m to 23m (50 per cent); in Italy 61m to 31m (49 per cent); in Portugal from 11m to just 5m (55 per cent); and in South Korea from 53m to 27m (49 per cent).
A further 34 countries are expected to see their populations drop by between 25 and 50 per cent, including China, where the number of people is projected to fall from 1.4billion to 732million.
The researchers said that the average age of people will rise as a result of lower birth rates and better survival, meaning the working age population will shrink and economies would suffer.
Some of the oldest countries will have to rely on immigration to make sure they have enough people to keep industry going, the scientists warned.
Professor Vollset 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.’
The researchers also projected a major increase in the number of elderly people. Over-80s will outnumber under-fives by two to one by the end of the century as fertility falls and life expectancy increases.
At the moment there are 681million children under the age of five — a figure that will fall to 401million.
The number of individuals older than 80, meanwhile, is projected to increase six fold, from 141million to 866million. Professor Vollset said this may have a major impact on the workforce.
‘While population decline is potentially good news for reducing carbon emissions and stress on food systems, with more old people and fewer young people, economic challenges will arise as societies struggle to grow with fewer workers and taxpayers.
‘Countries’ abilities to generate the wealth needed to fund social support and health care for the elderly [will be] reduced.’
Dr Richard Horton, editor-in-chief of the Lancet, added: ‘This important research charts a future we need to be planning for urgently.
‘This will truly be a new world, one we should be preparing for today.’
The researchers projected a major increase in the number of elderly people. Over-80s will outnumber under-fives by two to one by the end of the century as fertility falls and life expectancy increases. This could drastically reduce the number of people who are able to work in many countries, potentially damaging their economies