One Finite Planet

Peak Population 2055: Really? That soon?

First Published:


There are highly credible predictions (such as by Deutsche Bank) that we could reach peak human population as early as 2055. In fact we have already reached ‘peak child‘.  If we are on track to decrease by 2055, then we must be close to “peak under 35s”.  Digging deeper reveals it is definite we have stomped on the population growth brake pedal, and the stopping power is continually underestimated. What remains to be seen is will we stop, or just slow down growth to a crawl, and what will the implication be in either case?

Population growth took of in the early 1700s, so everyone alive on Earth today has only ever experienced a world where even history seems dominated by rapidly expanding human population, making claims of end to rapid growth sound unbelievable.  There are also frequently repeated warnings against ‘stagnant’ population growth, with dire economic consequences predicted and warnings of an unsustainable ageing population with insufficient young workers to support the elderly.  This post reviews these topics:

  • Can We Reliably Predict Population Decline So Far In Advance(2055)?
  • Prediction Threats: What Could go wrong?
    • Three Possibilities
      • UN: Peak Children and Fill the Pipeline (10Bn Peak)
      • Deutsche Bank: More Birth Rate Decline to Come (8Bn Peak)
      • The Ultra Rich and Powerful Disruption: More & More People Please!
  • Is A Population Peak a Positive, or is Never Ending Growth Preferred?
  • ‘Ageing Population’ and Economic Growth: Real Problems?
  • Conclusion

Can We Reliably Predict Population Decline So Far In Advance?

A decline starting in 2055?  How serious is a prediction be made 36 years prior to the event being predicted?  Who can predict in 2019, what will happen in 2055, with any accuracy?  Is this a case of make a future prediction that cannot soon be tested?

It turns out, a good analogy is a prediction that a car travelling which has been travelling at 110 kilometres per hour will stop in 36 metres.  Calculations on this linked page state that a car travelling at 110 km/hr will require 71 metres to stop. This means unless the car already has the breaks applied and has slowed to 78 km/h, the car will not stop in 36 metres!  So this is not equivalent to picking a random car travelling along the freeway and predicting it will stop, this requires picking a car that is already has the brakes applied and is behaving already as a car that will stop.

Population growth is slowing just like that car.  It takes almost an entire lifetime for population growth to grind to a halt in just one country, and globally, it takes even longer. A delayed impact of the ‘brakes being applied’ in some areas of the globe, means global population will take almost 100 years to grind to a halt from the time the brakes were applied, just like the car takes almost 100 metres to stop from 100km/h.

The brakes for population growth being a mix of contraception, improved education for women, better health care and lower infant mortality, women joining the workforce, and perhaps, even some influence from technology.  Research for the contraceptive pill began in the 1950s with first products by the 1960s, but there were limitations to supply to the general public, even within the USA until 1972. As you can see from the graph I have included, the brakes were applied around 1972, but it is safe to assume global adoption of oral contracption took longer, further supporting that there are also other factors at play.  This graph was simply from the first result I found from a search for “global population growth” as I wanted a result representative of what could be found from a search. Any data should be able to be accurate up to the date of publication, but the future, the “light blue shaded area”, is only a prediction.

What is clear from available data, is that the annual population growth has already dropped from 2.1% to 1.2%, which represents having halved. More significant in reality is the global “births per woman”, which has dropped from 5 to 2.5 in the same time.

This is a drop from around 2.7 births above the replacement rate (2.3) to around 0.2 births above replacement rate. A drop by a factor of 13 times!  A further drop in births per woman to somewhere between  2.3 and 2.1, is all that is required to trigger the end of population growth. The Deutsche Bank Report predicts a level of 2.3 by 2025, leading 30 years later to peak population in 2055.  This 30 year delay is caused by the population pipeline, which is the effect where there is a significant lag between birthrate and population growth.

The evidence is clear, we have already hit the brakes in terms of the rate of population growth.  Every thing necessary to stop population growth did commence back before 1970, so the forecast has some real evidence behind it. The question is: what will happen next?

Prediction Threats: What Will Happen Next?

Three Possibilities

If you have ever watched a car race, you may have noticed that sometimes, after applying the brakes and slowing down considerably, a car can then turn a corner and accelerate again.  As per the analagy, birth rates from this time forward could again accelerate.  Or the birth rates could continue to decline such that population growth stops, or this new ‘slower speed’ could become the new normal, giving three possibilies.

Before examining the possible next steps, it may be useful to put what has happened so far in perspective and examine just how effectively the brakes have already been applied. Considering that a ‘births per woman’ of 2.3 represents replacement level, the drop in birth rates from 5 per woman, to 2.5 per woman represents a drop from around 2.7 above replacement level to 0.2 above replacement level.  A level so low above replacement level it has been stated that we are effectively at ‘peak children’ level now.  Almost all population growth in the future will result from filling the population pipleline until all age groups are a result of the current almost static level of new births.

Option 1. UN: Peak Children and Fill the Pipeline at current rate (10Bn)

The most recent UN forecast is that having dropped from 5 to 2.5 globally in the past 50 years, birth rates may fall just a fraction further, to perhaps 2.3 or 2.2 in the next 50 years.   This means we are basically at peak children – or around the maximum level of children being born ever- now, or in the future. However total population of all ages added together will still rise as  population pipeline fills with generations born at this peak level replacing previous generations born in smaller numbers. As the pipeline gets closer and closer to being filled, the total population growth will decrease until it eventually stabilises. The UN predicts mortality rates in African and other high infant mortality rate countries will continue to improve, ensuring the birth rate stays every so slightly about the level of deaths from now until the end of this century.  The result being almost exactly equivalent to simply filling the population pipeline at the current level. The toal from this calculation is a peak total population of just over 10 billion in 2100.

Option 2. Deutsche Bank: Birth Rates Fall Further Given The Current Trajectory

The graph of world population growth shows a far less stable number over time, than the number from the graph of birth rates.  A key reason for the fluctuations of the level of world population growth,  is that the formulae for growth subtracts deaths of the elderly from births of babies, uses two numbers that are not closely coupled.   Population growth =  birth rate – death rate.  Death rate (at least of the elderly) does not directly drive birth rate.  People do not normally think, “oh, my great uncle Fred died, so maybe we should have another child”.   When looking at behaviour, look at is basically related to the rate people the number of people being born one lifetime earlier, but there is little evidence people are specifically motivated to ensure each dying person is directly replaced by a child, so the birth rate does not track the birth rate, meaning population growth is a less meaningful number than children per woman.

The better number to use to predict the future is the far more stable ‘children per woman’ rate.  The factors that have driven this rate downwards continue to apply and there seem no reason this number will magicall stop somewhere between the current level and the number between 2.1 and 2.3 which magically matches the death rate.  In fact in many countries, the rate has already fallen to as low as 1.4.

The Deutsche Bank projection is that the rate will fall to 2.3 by 2025, and then continue to fall to around 2.1 by 2055, after which time they stop projecting.   These numbers result in a peak population of around 8 billion that is decreasing from 2055.

Option 3. The Ultra Rich and Powerful: More People Please!

Throughout history, countries have sought to create empires.  The maximum population possible under one rule.  The path to power and extreme wealth is a big population.

The average citizen may be better off in smaller counry such as Switzerland, or one of the Scandinavian countries, but none of those smaller countries can deliver the power or wealth available within much larger countries such as the USA, China or India.

The same drive that pushed the wealthy and powerful to create empires, is behind a push today for population increase.  The ever present messages in English speaking countries as the US, Canada, Australia and New Zealand is that population stagnation is a recipe for economic catastrophe. This is despite the fact that countries thse countries have population pyramids already reflecting full poulation pipelines.  Almost every economically developed country in the world now has a full pipeline, with immigration currently the resource for increasing population.  While the socially liberal members of society welcome immigration, the goal of population growth to futher the goals of the extreme rich and powerful is frightening, as immigration may give way to attempts to artifically drive up birth rates.

A second factor that can drive up birth rates is religious extremism, which can also seek to drive up birth rates to increase the relative population of specific groups.

The third factor that could increase population is a medical breakthrough that reverses aging.  If lifespans start to increase significantlly beyond current levels, the number of people alive at any given time also increases.

A Population Peak? Positive, or Never Ending Growth Preferred?

The Growth Proponents

Search ‘Overpopulation’ and you should find many stories that suggest people in the 1960s and 1970s were forecasting global catastrophes due to overpopulation and these people all got it wrong.  We have continued to grow the global population and everything is fine. The rules of the ‘petri dish’ where expansion eventally leads to starvation do not apply to humans.  Famines are lower with our huge population today than they have ever been in the past.


The fact is, examine the graphs above, and humanity basically turned off the poplation growth engine around 1968. Had the population growth continued at 1960s levels of 2.1% per year from the 4.3 Billion at the time we would now be at 1.021^50*4.4 = 12.1 billion.  In other words, we would have added more than twice as many humans since that time.  Perhaps there was a reason to be frightened, and we did avoid a potential catastrophie?

Or did we? Other species on Earth are dieing at a perhaps unprecedented extinction rate level as the Earth struggles to support the over 7 billion people now on the Earth.   People set targets such as reducing emissions by 55% by 2030 which would be rather simple if we had 55% less people on the planet.

It is hard to picture the entire Earth.  So simply picture your house.  Sure, you could add far more people. But as you, past a certain point living standards of those in the house decline.  There is too much garbage to be collected in allocated rubbish. You can avoid everyone starving in the face of a huge increase, but well before the starvation point the enviroment suffers and living standards of those in the house are impacted.  This is a model for the Earth.  Sure, the very rich and powerful who desire growth can ensure they have plenty of space and resources, but not so the rest of humanity.

The counterpoint is that we are already past the point of ideal population. Yes, we are not all starving, but we can afford to eat many of our favourite foods anymore without depleting natural resources.  The Earth is straining under the load, and our lives are already negatively impacted, as it the planet.

‘Ageing Population’ and Economic Growth: Real Problems?

One protest is : “If we halt population growth, then ‘ageing population‘ will be a disaster”. But, if ageing population was such a problem, the Niger would be a rich utopia and Germany an economic disaster. Strangely, this may not be the case!  A key reason why Germany is coping fine and Niger is not an automatic success, is that having lots of elderly people is no more a drain on society than having lots of pre-working age children. In a parallel, we seem to be at risk of creating a society where there is simply not enough work to keep the working age people we do have employed.

Per capita economic growth benefits all in society, but gets more challenging as resources levels per capita decline with population growth.  Gross economic growth lifts the top 200 companies (or however many in the relevant index) and benefits those who own shares in those companies.  Basically, population growth helps gross economic growth which benefits the very wealthy within society, provided the number of very wealthy does not also grow in number.  Population growth actually works against per captia wealth.


We have, perhaps, already made all steps possible to avert a population driven disaster.   This does not mean the disaster will be avoided, just birth rates have fallen to level that will help minimise the disaster.

But is it possible population will peak by 2055 at a level below 9 billion?  I really hope it is, but perhaps because population is still rising, it just seems hard to believe.  I know the current growth it is perfectly explained by filling the pipeline, and that hard data does support that we have turned the corner, but it just seems to good to be true.  Perhaps that is why the UN makes the more conservative projection that growth will continue longer.  If the UN projection is high, there are no negative repercussions, but if the UN prediction is too low, they have a lot to anwer to.  Plus, there is a risk of waking those pushing for infinite growth from their slumber.

The biggest risks now are:

  • the population level is still to high and birth rates still too high for an ideal outcome
  • no matter what we do, the damage is already done
  • the very rich and very powerful empire seekers find a way to drive birth rates higher again

One Response

  1. We can barely support the current population of 7.6 billion thanks to fossil resources but those resources are peaking.
    Conventional oil peaked in 2016 & our civilization is totally DEPENDENT on conventional oil, fracked oil has less energy per liter than conventional oil & depletes much faster, 3-5 years & a fracked well is toast but it is good for adding to heavy, sour crude like Venenzualia has which is why the US is trying to wage a war to steal their oil.
    The US war machine must have OIL!

    The US empire wouldn’t exist without affordable oil & it along with most of us, won’t exist after the fossil resource age is over with. Those so called “renewables” are just a OIL DEPENDENT TECHNOLOGY & we cannot replace declining resources with a resource dependent technology!

    I think our population will collapse much sooner than 2055 because of energy & resource depletion & climate disruption.
    If we are stupid enough to engage in a nuclear war, than it’s probably all over for every living thing.


Table of Contents


Optimum population of humans: Ideally, how many people can, or should, the Earth support?

It can seem like the human population can grow forever, but analysis makes it clear growth must stop eventually. The question becomes at what level should it stop?

Do we go for the maximum possible people before everything collapses, even if average living standards could be far better with a smaller population? Is it like a chicken farm in an egg farm, where having less chickens is seen as preferable if it means chickens get better living conditions? What population strikes the right balance for humans?

Read More »

Overpopulation: starvation is the last symptom.

The Myth: Starvation will provide a warning of overpopulation. The Truth: In nature, we define overpopulation as when sustaining the population results in damage to the environment.

Plagues are a problem were before the plague population starts to starve.

Starvation will be a consequence only when overpopulation has resulted in environmental collapse that will result in a rapid population collapse. Starvation is useless as an indicator, by the time there is starvation all environmental food reserves have been consumed, and catastrophe is then unavoidable.

Read More »

Next steps for mankind don’t include the Sci-Fi dream of a new home planet.

There is a dream, often explored in science fiction, where humanity inhabits not just one planet, but many.

While the dream is still centuries away, as is ‘Earth 2.0‘, the reality, working towards small outposts on Mars or the Moon or even beyond is overwhelming compelling and can provide many rewards.

Humanity may get back up outposts, but for centuries, will have no real second home, and over 99% of us will still need to live on our one finite planet.

Read More »