The major development underpinning the prospect for an early-century peak in human population and even earlier peak in civilizational power is a rapid and seemingly unexpected decline in fertility rates across the world. All regions except Africa are now below the replacement rate, and still falling.
This short post—probably my last on the population topic for a while—is centered on the following animated GIF showing how the United Nations’ demographic models have expected total fertility rate (TFR) to evolve into the latter part of this century.
U.N. TFR projections from 2010, 2012, 2015, 2017, 2019, and 2022.
Every few years, the U.N. releases a demographic projection model that includes an expectation of how TFR will behave going forward. I have already pointed out the glaring discontinuity (kink) at 2020 in the latest projection and a gallery of systematic major misses at the country level. What the animated GIF above helps us see is how stubborn the imagined far future is—consistently aiming for a one-size-fits-all convergence.
I have referred to the notional TFR endpoint as a “magnet,” acting like a theoretical convergence point to which all regions are attracted. We see how persistently influential this magnet is on projections in the sequence above.
Okay, so the target point does change a little bit—beginning around a TFR of 2.0 in the 2010 projections, and walking down to 1.7 by the latest projection. So it is not utterly unresponsive to recent trends. But look at the persistent kinks in many of the curves at the moment the models take over. The fact that all the regions (except Africa, after the 2010 projection) converge to the same tight spot speaks to a uniform, stabilized vision of the future that can be nothing but notional. Such a development would be a break from the history of ever-changing TFRs. It’s as if someone believes we’ll finally figure it all out and settle down for a long reign of stability. What it really means is that extrapolation-based projections more than several decades out become highly suspect.
Falling Fertility Factors
First of all, I will register my dislike of the term “fertility” in the TFR metric. It sounds purely biological, like an intrinsic capacity of baby-making humans. Now, indeed some of the TFR decline may be of biological origin as sperm counts decline, endocrine disruptors abound, and microplastics are found everywhere we look. But at least as much of the phenomenon may stem from the myriad reasons people elect not to have children.
The non-biological factors at play for deciding not to have children might include:
- Too expensive (hard enough to tread water without kids)
- Lack of stability (no steady career/job; gig economy; not settled in one place)
- No house or expectation thereof (common practice is house first then family)
- Messed up world (polarization, climate change, environmental harms)
- Increases in non-traditional sexual and gender identities
- Social disconnection in an increasingly virtual world
- Disillusionment and bleak outlook (why perpetuate this terrible game?)
- Resentment at being seen as baby-making machines by a greedy capitalist system
- Do the opposite of whatever that gross Musk wants (and other pro-natalists)
These are not well-researched conjectures, and may be off base. I’m sure you can think of more. The point is, lots of factors are contributing, and these dynamics are not likely to turn around quickly—some likely to become even more pronounced. Therefore, the sharp drops in TFR seem likely to continue for the next decade or so, and that may be all it takes to reach peak population and peak civilizational power in the next 10–20 years—just in time to make the Limits to Growth work look eerily prescient (see LtG plot from last week). After that, demographic inertia will continue to exert an influence as reduced numbers mature to child-bearing age.
I would hope the reaction to this development is not to advocate policies to “restore” population growth. That’s the last thing the planet needs, and stems from a misplaced allegiance to economic fantasies rather than to the community of life (the economy would fail anyway without a functioning ecosphere). A natural population decline by the non-violent process of simply not bearing children would be a gift to humanity and to the earth that supports us.
Positive Feedback
We have no modern precedent for declining global human population, so cannot confidently predict what happens in such a scenario. In the short term, I can imagine more positive feedback mechanisms that accelerate the plunge than corrective negative feedback mechanisms—as it won’t feel “safe” or ethical to bring children into a period of great uncertainty.
Firstly, the economic house of cards—essentially a Ponzi scheme predicated on unsustainable growth—will likely collapse. Since we foolishly based most of modern life on this inherently shaky economic foundation, its implosion will be felt far and wide, potentially setting off violent conflict and famine as nations struggle to maintain their expected but unsustainable material and energy flows. Even without this unfortunate development, how many of the factors itemized above would be reversed? Many are only exacerbated, which could lead to a faster population decline.
My best guess is that whether the process is quick (famine, war) or moderate (demographic factors alone, let’s hope), the process will remain in a positive feedback condition until most of the unsupportable complexity has melted away. At this point, the period of positive feedback might self-terminate as groups of people find themselves enjoying locally self-sufficient lifestyles that are ecologically stable and disconnected from the complexity that once bound modernity together in the same trap.
The New Era
Whatever happens after modernity necessarily self-terminates (one cannot choose or decide to continue a grossly unsustainable approach to life), it won’t be planned, and it probably won’t be monolithic. Differing conditions, remnants, and cultural attitudes around the world will lead to different experiments in what to try next. As with modernity, those practices that are not sustainable will eventually fail (possibly destroying sustainable groups along the way, as has happened plenty of times before). Those that are able to find ecological balance (in right- or reciprocal-relationship with the community of life)—and are isolated from bad actors until those actors necessarily fail—stand a chance at longevity. It’s not a choice, but a fact in the long term. Only those modes of living that are sustainable in relation to the ecological whole can survive.
We who are alive today will not see the outcomes, but based on what I have learned from demographic trends, it seems more likely than I previously thought that we will see convincing evidence of its kick-off by mid-century. Perhaps the best we can do now is in the spirit of acceptance, so that we might re-define what matters and thus what to prioritize during the transition. Clinging to modernity would be a poor choice, doing more harm than good, in the end.
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When I begin to think in terms of a system and all the chains of relations between parts and individual elements, I really do not see the possibility of a gradual decline…
When one of the systems reaches a critical mass, like a mudflow, it will pull and absorb everything around it.
This makes a lot of sense – as you say, practicing a spirit of acceptance and re-defining what matters (and what to prioritize) in the years ahead.
Another blogger, looking at growth, was cool to policy and proposal advocacy, e.g., how to fix or ameliorate future problems – because humans will not agree quickly enough to make a difference—assuming (idealistically ) that we can agree on anything.
Yet, priorities around children are not really policy choices. This suggests that accepting and redefining can take place outside of official policies. That's something at least.
All you have to do is move people out of rural settings into cities. Women gain education and everyone has to spend most of their time indoors. The combination of empowering women and overcrowding drops birth rates everywhere. Elon Musk only prevents about 10 percent of westerners from reproducing, which is his greatest contribution to the world.
Is this tongue-in-cheek?
Sounds like a recipe for disaster to me!
Where will the food come from?
What I see is quite the opposite: a flight to the land, as industrial output and food production drops and jobs go away. I base this on the Limits To Growth model, which has been validated and re-calibrated many times.
So-called "renewables" are not supplanting fossil fuel; they are supporting growth on top of fossil fuel, which has stagnated.
The record shows that, as long as energy grows, population will grow. We should be preparing for de-growth; instead, it's business-as-usual.
One more non biological factor may be less experience and exposure with babies as teenagers and young adults. Earlier generations had lot of interaction with babies and infants with starting at very young age and current generations completely laks this. My mother was the eldest of her family and she got lot of help from her younger siblings (Youngest uncle is only 8 years older than me). I did the same for their sons and daughters. So you have plenty of time with babies before you start your own family.
Excellent point: when the norm is 1 to 3 kids within 8 years, that experience is gone.
I'm not convinced that conventional demographics is up to the task of making predictions through a phase reversal.
All evidence is that energy consumption, industrial output, and food production are all going to peak and then decline. I doubt that the official population projections have taken that into account.
Civilization is in a situation where growth is absolutely necessary. You won't find a politician or business leader who is against it. And yet, most sane people agree that it must reverse!
Consider some of the myriad ways the conventional population models depend on growth. Even today, many countries are deathly afraid of de-growth. Many countries that are experiencing it are offering incentives to have larger families, for example, or aggressively inviting immigration.
Currently, retirement is entirely dependent upon growth. In the future, either population growth must continue in order for retirement to continue, or people must die before they reach retirement.
I think the birth rate will go up, rather than come down.
This may well be balanced by early death and childhood death, as modern health care systems fail. But the relatively simple, assumptive demographic models are fraught with peril.
There will certainly be "peak population" at some point, probably sooner than models predict, but it won't be based on "educating women," and it won't be pleasant.
Hi Jan, Tom,
IIRC the Limits to Growth model predicted a rise in birth rates as industrial output available for investment in social capital (hospitals, medication, education) fell back toward Africa levels. But life expectancy was also falling quickly. I would need to go back and look again. Dynamics of Growth in a Finite World is the academic text that backs up the laymen oriented Limits to Growth. Donella Meadows did the population model and wrote up her rational.
Unlike the 1970's there may now be several nations that have gone through economic decline that could help guide our understanding of the curve. I am guessing that different driving factors will take over the feedback loop as social capital falls. Thus it would be important to pick different examples at different social capital levels: Former Soviet republics, Somalia, Haiti, Sudan, etc. Cuba might make an excellent natural experiment when compared with other gulf island countries.
Another thing that will cause population decline is the collapse of industrial agriculture. Jem Bendell has a paper on this subject
https://insight.cumbria.ac.uk/id/eprint/6927/1/Bendell_BeyondFedUp.pdf
Here is a TL;DR for (from the paper itself)
1. We are hitting the biophysical limits of food production and could hit ‘peak food’ within one generation;
2. Our current food production systems are actively destroying the very resource base upon which they rely, so that the Earth’s capacity to produce food is going down, not up;
3. The majority of our food production and all its storage and distribution is critically dependent upon fossil fuels, not only making our food supply vulnerable to price and supply instability, but also presenting us with an impossible choice between food security and reducing greenhouse gas emissions;
4. Climate change is already negatively impacting our food supply and will do so with increasing intensity as the Earth continues to warm and weather destabilises, further eroding our ability to produce food;
5. Despite these limits, we are locked into a trajectory of increasing food demand that cannot easily be reversed;
6. The prioritisation of economic efficiency and profit in world trade has undermined food sovereignty and the resilience of food production at multiple scales, making both production and distribution highly vulnerable to disruptive shocks.
Considered individually, each one of the hard trends presents a very significant challenge to global food security. Considered collectively and interdependently, it becomes clear we have created a predicament on a scale and depth unprecedented in modern history, and unprecedented for the sheer number of people who will be affected.
Bendell, Jem ORCID: https://orcid.org/0000-0003-0765-4413 (2023) Beyond fed
up: six hard trends that lead to food system breakdown. Institute for Leadership
and Sustainability (IFLAS) Occasional Papers Volume 10. (Unpublished)
The paper is also available on Soundcloud.
https://soundcloud.com/jem-bendell/food-collapse-chapter-6-of-breaking-together
Seems like there is a great episode of the “great simplification” in this series of posts Tom!
Already scheduled! (Recording early August; likely not out until late September?)
I took a deeper look at the population sub model in World3. (Dynamics of Growth in a Finite World) [Remember that these dynamic models were not built to predict the future in absolute values, but instead sketch the shape of the behavior mode: exponential growth forever, s curve approach to a limit, oscillation around limit, overshoot].
The fertility side of the population model contains the Demographic Transition (represented as rising GDP per capita causing a drop in desired family size) through a delay function. So as people become wealthier, they have fewer kids, but that lowered expectation is delayed ~10 years. Another adjusting factor looks at income expectation and reduces desired family size if income is falling rather than rising. (which we certainly see in Russian demographics).
Finally, if mortality is high, demographers were suggesting that parents desired extra children to make sure some survived. They factored that in.
Thus parents have a desired family size vs actual family size. Social spending per capita determines access to advanced contraceptive methods allowing parents to more accurately achieve their desired family size.
So what happens is that on the rising GDP side of peak is that as wealth increases the desire for children slowly shrinks (back in the 1970's they put in a value of 3 kids, we now know it is lower) and social services mean that parents can reach their desire. On the falling side of peak incomes decline. That would push family size larger (lower GDP per capita), but with a delay. The delay plus the declining income factor actually pushes the desired family to be even smaller as the system moves through industrial peak.
Eventually incomes will fall enough that family size will start to rise. Lack of social spending per capita means contraception will be scarce. Parents will have more children than they plan (again). Birth rates will rise, but population in industrialized countries will be well past peak.
If these model assumptions hold true, then I cannot see nations facing economic decline from energy uncertainty, like Europe, increasing fertility for the foreseeable future. All net importers of energy actually.
An interesting question for me is what will happen in those nations that never made the demographic transition (and due to resource shortage never will)? And how will nations with a shrinking population deal with people trying to immigrate? Limits to Growth does not model nations and cannot address those questions.
Russian Demographic Trends look to support economic uncertainty and falling income lowers fertility:
https://www.mdpi.com/2227-7099/11/10/245
Hi Tom,
I enjoy reading your articles. If only more people would read them and reflect upon them…
I have a question, the answer of which I can probably imagine but I will ask nonetheless. It seems like a collapse of various things is approaching (this has been the outcome of my research too). Do you think there is anything realistic that we could do to prevent it? My assessment is that there is nothing we could do, and thus I have simply tried to accept it—or still trying… since now and then I think about it again. What do you think?
Best,
Lazaros Giannas
I have come to realize that modernity, being woefully unsustainable to its foundation, has no chance of continuance. It's not a matter of choice or desire, but simply that unsustainable things fail by definition. Best thing is to stop betting on the losing horse, and get to a place where its failure isn't irksome. One might find enthusiasm in imagining the positives of other ways of living beyond modernity.
Two articles in the UK Guardian and Observer this weekend illustrate the dissonance of economists with falling birth rates. No mention of overshoot or all the associated problems facing humanity – just more babies please! The monster needs to be fed.
https://www.theguardian.com/business/article/2024/jun/30/the-baby-bust-how-britains-falling-birthrate-is-creating-alarm-in-the-economy
https://www.theguardian.com/commentisfree/article/2024/jun/23/the-falling-birthrate-threatens-a-disaster-so-costly-no-politician-dares-think-about-it
It is very depressing to live in a community that is thinning out due to population shrinkage. Soon anyone with any ability leaves, the schools close so no new families arrive and you are left with old people hanging around waiting to die. You can see this happening in Italy (villages where houses are being sold for one euro) and Japan where 14% of houses are empty and worthless and many villages have shut the last schools so no more young people there.)
The WHO have long predicted that depression would be the major health problem in the future. This now seems prescient.