An Exploration of Key Topics Shaping the Future.

Why wait? We should end population growth NOW!

I have been asked on a few occasions, why not end population growth now? It is not like we need to get more people first. Japan has stopped population growth, why not the rest of us? What are we waiting for?

  • What is needed to stop growth immediately: Births equals deaths.
  • But Japan Has Managed It?
  • Realistically? What Is Soonest Growth Could Stop?
  • What Is The Ideal?
  • Threatening Problem: What Could Prevent The Ideal?

What is needed to stop growth immediately: Births equals deaths.

Fail: Two parents, Two Children Families Takes 3 Generations To Stop.

At first glance, it would seem logical that families had one child for each parent, then population numbers would be stable.

Unfortunately, it is not that simple, and while this works eventually, it takes 3 generations to stop population growth.

Think of a house where a couple live. Two people in the house. Then they have a child, and now there are three people. The population just grew! If one of the parents died there would still be two people, or if a grand parent or great great parent had recently died, or was about to die, then the balance would be restored. However, for this to work, there needs to be same number of children not just as the parents, but as grandparents or great grandparents. This would require:

  • Two parents, two children.
  • Two sets of two grandparents, four children in total.
  • Two sets of two sets of great-grandparents, eight children in total.

Stable population means births = deaths. Having the births of the children balanced by the deaths of their parents will work, but population grows until the parents die, which hopefully is not now. The deaths around now will come from grandparents or great-grandparents and will only be in balance if the grand parents and great-grandparents also had two children. In most countries, this is not what happened, and we can’t go back and change the past.

But all this shows is that two parent, two children, could take three generations to solve the problem. In fact we are now at peak child, and in three generations the problem will be solved. But the questions is, what is needed to solve the problem now, and this just shows what doesn’t solve the problem. At least, not now.

Ourworldindata: Interactive

So How Many Children Can Each Couple Have?

The graph here show actually births vs deaths up to 2020, and estimates into the future. Of course, the future is not locked in, and the entire premise is what is needed to create a specific, and different, future.

From the data, in 2020, globally there were 140 million births and 59 million deaths, which is a population increase of 81 million! Even halving the number of children born would not stop population growth immediately, even though ‘births per woman‘ is less than 2.4.

How does this make sense?

The births, were children born to parents centred around the 25-29 year age group, and the deaths were to people centred around the 75-79 year age block. Yes there are parents and deaths from outside these age blocks, but as the median age group, these blocks give the best indication of the relative sizes of the group typical of children, vs the group with an age most typical of those dying.

The world population pyramid for 2020 reveals 598 million people in the 5 year age group aged 25-29, which on average rounds to 120 million parents for those 140 million children. More than 2 children per couple, and equating to 2.33 children per woman, which is overall the number for a stable population in the long term.

The problem is, right now, there are not enough people in dying, the peak age group were born 75 to 79 years ago, when the world population was less than 1/3rd of what it is now.

The number of 75-79 year olds on the current population pyramid is even smaller than the base to calculate from, as this is the typical age, and some have already died. Go back 60 years, and these people would have been 15-19, and it is that population that should be used.

From back in 1960, there were 258 million in the correct age group, which suggests approximately 52 million per year, would be expected to be dying per year now. Reasonably close for an approximation, given the years of death have an even bigger spread than peak years for being parents.

It becomes clear that even a global 1 child policy is not enough to stop population growth immediately, but it would be most likely close enough, and within a few years as the elderly grow in number, we would very soon move from halting growth, to rapid population correction.

But Japan Has Managed To Stop Growth?

Japan has already ended national population growth, and has not needed to reduce births to 1 child, but a more reasonable 1.4 average births per women.


The secret is Japan achieved this by starting reducing family sizes earlier. While the two children per family model can take 3 generations, 1.4 children per family does reach the target of stopping growth much sooner, and has the benefit that it can then, if desired, provide a period of population correction. Note Japan has already had around 40 years of less children born every year.

The graphs on this page tell the story of ending population growth:

  • 1960s world graph from the time of fast growth.
  • 2020 world graph from the start of ‘peak child’.
  • 2020 Japan graph with population correction starting, after 40 years of reduced birth rates.

Realistically? What Is Soonest Growth Could Stop?

Globally, births per woman is currently still at around 2.3, having fallen from around 6.0 prior to 1900, when infant mortality was still high. We have had a population explosion triggered by a fall in infant mortality, but the explosion is now ending.

If the word follows the path of Japan, it could still take another 35 years before the population is decreasing, and if we follow some UN projections where having fallen to 2.3, births per woman stops falling, it population growth could persist until the end of the century, provided the resulting numbers themselves don’t cause a disaster.

Realistically, even if you do accept that the fact we are unable to exist sustainably means we are overpopulated , without a massive intervention, the very fact that population of elderly people is so much smaller because they were born when population was smaller, means population keeps growing for at least another 10 years.

What Is The Ideal.

Personally, despite the fact we are already overpopulated, I believe any disruption so severe as to halt growth right now is likely to reduce the planets carrying capacity of humans, and make overpopulation an even worse problem even without having more people.

Ending growth smoothly in 10 or even 20 years I think is the best we could hope to achieve.

Threatening Problem: What Could Prevent The Ideal?

There are loud voices calling for an acceleration of population growth as the only economic solution. Cries that ‘ageing population’ will be too expensive, and other stories that make no sense when examined properly.

But consider the comments of Jeff Bezos on returning from his trip to space. His wealth results from all the people in the world who buy from Amazon. If there were less people in the world, he would have less wealth.

Jeff Bezos gave a heartfelt thanks to Amazon employees and customers following his record-setting trip to space Tuesday — noting that they “paid for all of this.”

“I … want to thank every Amazon employee, and every Amazon customer because you guys paid for all this,” the 57-year-old Amazon founder told reporters after returning from his trip to the edge of space.

“So seriously, for every Amazon customer out there, and every Amazon employee, thank you from the bottom of my heart, very much. It’s very appreciated.”

Jeff Bezos thanks Amazon workers, customers for bankrolling trip to space

But it not just those few billionaires for whom it is “more people equals more wealth”. The same applies to companies such as Apple, Facebook, Google and Amazon. Not that any of these companies is in a position to influence how people think… oh wait, they are valued at trillions of dollars on the basis of their ability to do just that, and can even get people to believe the Earth is flat. Ok, so admittedly it is that small minority with the greatest ability to influence opinion, just happed to the ones who benefit from population growth. And yes, you would think that in an equitable world, more people would also mean more shares and shareholders for these global companies, so the individual share price and wealth of each shareholder would not change as population increases. But it just may be, we don’t live in that equitable world quite yet.

Anyone who believes in indefinite growth in anything physical, on a physically finite planet, is either mad or an economist.”

Attributed to Kenneth Boulding in: United States. Congress. House (1973) 

Table of Contents

No more posts to show