This week, the world’s population passes a historic milestone. But in the next century, society will be dramatically reshaped, and soon we will reach a decline that we will never reverse.
We never know precisely how many of us are alive at any given time, but this Tuesday is the United Nations’ best estimate of when we will reach 8 billion human beings.
Eight billion. It’s a number too big to imagine, but think of it this way: In the time it takes you to read this paragraph, the world’s population grew by about 20 people.
Although the Earth’s population is growing rapidly, the rate of growth is beginning to slow. Eventually, it will begin to fall and our societies will shrink.
Humanity is changing day by day in ways we cannot perceive for short periods, but in ways that will change our world for the next century.
Fertility peaked in the 1950s, when women had, on average, five children each. (Unsplash: Christian Bowen)
We have already reached peak children: there will never again be more children alive than there are today, with falling fertility rates around the world.
How will we take care of the aging population? (Unsplash: Eberhard Grossgasteiger)
We’re getting older and older, which means there are fewer people who can work to support more people who can’t.
Cities are spread across every continent. (Uncredited: Pawel Nolbert)
Cities are expanding, chewing up farmland as they go.
Africa has some of the highest fertility rates in the world. (Usplash: Annie Spratt)
We are seeing a great transformation of the world’s huge population centers.
“This is a fundamental transformation of what a society looks like,” says Elin Charles-Edwards of the University of Queensland.
“We went through quite an extraordinary period from the 20th century to the 21st century, where we went from demographic regimes where there were lots of children and people were dying younger to a period of very rapid growth.”
Now we have to contend with consequences and opportunities.
But to understand what all this means we have to start at the beginning.
We’ve come a long way, fast
Homo sapiens have roamed the Earth for roughly 300,000 years, more or less (no one kept a diary back then).
We evolved to have big brains and long legs, but our population grew relatively slowly at first.
There were perhaps 230 million of us on Earth around the time of Cleopatra’s death, when the ancient Egyptian civilization came to an end.
The population had more than doubled with the Renaissance in 1500 and doubled again in 1805, when the ancient Egyptian civilization was being rediscovered with the help of the Rosetta Stone.
All of these estimates are pretty rough—we didn’t have comprehensive censuses in the Middle Ages—but the human population has been on a slow burn, until recent centuries, when it has grown.
The 2 billion mark was reached just before the Great Depression in 1925, and it took only 35 years to reach the third million.
Since then, the population has increased by another billion every 10 to 15 years.
Where are we going?
The world is likely to have a couple of billion more mouths to feed in a few decades.
The latest UN projections, released earlier this year, suggest the world will be home to around 9.7 billion humans by 2050.
“Demographic projections are very accurate and have to do with the fact that most of the people who will be alive 30 years from now have already been born,” says the director of the UN’s population division, John Willmoth .
“But when you start getting into your 70s or 80s down the road, there’s a lot more uncertainty.”
There is a limit to the population that the world can be. (ABC News: Mark Leonardi)
Under its most likely scenario, the UN predicts the world’s population will reach about 10.4 billion by the 2080s.
From there, it fluctuates for a couple of decades, before falling around the turn of the 22nd century.
But the range of reasonable possibilities in 2100 is considerably wider, between 8.9 billion and 12.4 billion.
There is another international population growth model, published by the IHME health data research group, that predicts an earlier population peak and faster decline.
“The main reason we predict a different global population in the last third of the century comes from the way we’re modeling fertility,” says senior research director Amanda Smith.
“Our model suggests that we expect fertility to continue to decline until the end of the century in many countries, contributing to a larger and faster global population decline than projected by the United Nations.”
The magic “replacement number” is 2.1: If women on average have more children than each, the world’s population grows. If fertility rates are lower, the population shrinks.
And that’s where we’re headed.
“We have now reached the peak of the child,” says Dr Charles-Edwards. “There will never be more children alive on Earth than there are today.”
Fertility peaked in the 1950s when women had, on average, five children each.
This figure varied dramatically between regions of the world.
But since then, fertility rates have reliably fallen. In fact, in some parts of the world, such as Australia, Europe, North America and parts of Asia, fertility rates are already below this replacement number.
Australia’s population is only growing now because of our immigration program.
Different fertility rates between regions mean that population decline will be seen in some regions sooner than others.
It has already started in some nations.
Countries in decline
Around the Balkans, the nations of Bulgaria, Lithuania, Latvia and Serbia are at least 1% smaller this year than last year, according to UN figures.
Ukraine shrank considerably more, a consequence of emigration caused by the ongoing war.
A few more countries are expected to have smaller populations in 2050 than now.
These are countries with low fertility rates and immigration levels that are not high enough to make up the difference.
Because fertility rates are falling everywhere, as the decades go on, more and more countries on this map will be colored.
And little by little, the world will grow old.
We cannot avoid old age
Humans like to focus on the beginning of life and not the end. We are not good at talking about aging and death.
But the world’s demographic change will transform our society, and we cannot hide.
“If you want to think about future demographic challenges, I think population aging is probably number one in terms of people needing to change the way they do things, their expectations, governments needing to change public systems that support the elderly,” said Mr. Willmoth says.
Some of the consequences are relatively obvious, such as increased demand for health services and care for the elderly.
IHME’s Amanda Smith says that as part we should expect “a shift towards a greater burden of disease from non-communicable diseases” and that in many countries the COVID-19 pandemic has exposed weaknesses that will need to be addressed.
Dr Charles-Edwards says our tax base will need to support more and more people.
Countries with government-funded age pension schemes will see welfare costs rise, and then there’s the problem of having enough workers.
“We will have more and more countries where there are more old people than young children,” he says.
“This is going to really shape the way we make decisions about how we govern, how we spend our money. It’s a massive cultural change.”
Families are getting smaller and downsizing homes for the elderly is already on the agenda in many aging countries, including Australia.
The transport is designed for commuters on their way to work. (ABC RN: Nick Wiggins)
But what about our transport systems, which are great at getting people to offices in capital cities, but not so good at getting us to shops, parks, doctors’ clinics and the suburbs?
City streets are not optimized for a larger population. (AAP: Bianca De Marchi)
What happens when we go to work less each day and need help getting around more?
Not only will the composition of our societies be reshaped, but the texture of our cities and the way we move around them.
“We have to design cities in, say, somewhere like Australia with the view that there will be many more older Australians here, so thinking about walkability and accessibility is very, very important,” said Dr Charles Edwards. he says
It will also change jobs. With fewer workers available and more jobs needed to care for the aging cohort, companies may need to look to automation, artificial intelligence and robotics to help fill the gaps.
Entrepreneur and artificial intelligence expert Vaibhav Namburi says workplaces may look very different with the increased use of automation.
“I think in the next 10, 20, 30 years we’re going to see a lot of ‘mundane’ or repetitive jobs being eliminated, and those people [will] be retrained to focus on more higher-level skills,” he says.
So maybe we will all work smarter, but will we also work harder? After all, during the pandemic, remote working has caused many of us to work longer hours.
“[That] it was actually the opposite of what the whole remote flexible working lifestyle wanted to bring,” says Namburi.
“I’ve got my fingers crossed that the next hundred years will be more focused on the mental health aspect of our work-life balance.”
Countries are growing fast
Some parts of the world face a different problem.
In the map we saw earlier, you may have noticed that there were no nations in Africa with declining populations.
In fact, Africa is one of the fastest growing places on Earth right now.
Just eight countries are predicted to be responsible for more than half of the world’s population increase by 2050.
One of them is India, which is poised to overtake China as the world’s most populous country…