Global population could peak below 9B in 2050s | Hacker News Reader

Global population could peak below 9B in 2050s

earth4all.life

29 pointssolalf52 comments

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This is the paper the post is based on: https://earth4all.life/wp-content/uploads/2023/04/E4A_People...

Comparing UN projections from 2019 and 2022:

https://en.wikipedia.org/w/index.php?title=Projections_of_po...

https://en.wikipedia.org/wiki/Projections_of_population_grow...

There's a visible shift towards the low end, with the peak now happening in this century, instead of the next.

I think it's unlikely that the global population will peak below 9bln, but below 10bln in within the realm of possibility, considering that it already had been revised by close to half a billion.

I take any prediction for something >30 years away with a large grain of salt. There are just too many black swans that can happen. I.E global wars, technological/medical breakthroughs, effects of global warming etc.

Once again a publication that points to the overconsumption problem of the wealthiest. I think we lack target models to show people what is too much. Carbon footprint calculators are a nice tool for this. Air travel impact always blow me off. I guess « Limits to growth » can count one more validating study.

https://goodlife.leeds.ac.uk/ is one I keep thinking of which makes me inquire deeply around what social structures / values humans may need to seek to live within planetary boundaries.

Here we go again... Everybody's ignoring the most basic and evident of behaviours (baby-having age moving up), and this one focuses on GDP-per-person without accounting for differences year-on-year but only comparing aggregated data over a period of time, thus smoothing out actual behaviour of a population. All of them also ignore that women (primarily) are learning how much harder it is to have kids at more advanced age, and that we might see a social reversal to have kids at a younger age again.

Let's take Germany as a counter-example: their GDP is still growing (https://www.macrotrends.net/countries/DEU/germany/gdp-per-ca...), yet their fertility rates are still growing too (https://www.macrotrends.net/countries/DEU/germany/fertility-...). It's not an isolated case, let's check out Romania: https://www.macrotrends.net/countries/ROU/romania/gdp-per-ca... and https://www.macrotrends.net/countries/ROU/romania/fertility-.... Check out UK as well for when a decline in economy does not result in increase in fertility rates.

Yes, there is a trend in the developing world for fertility rates to reduce as economy improves, but then in the developed world they start to bounce back up even if economy keeps improving. How is this not obvious to everyone doing these modelling studies?

I am guessing fertility rate never stabilises, and major effects like when we'll add 12% of the population are surely predictable from behaviour of large nations like China, India and nations from Africa (who are mostly in their developing phase, or fast decrease of fertility rates for urban populations), but these are compound variables and any correlations noticed are probabilistic and not causation in most cases.

I think we can go higher with stuff like deserts covered in glass algae growth tubes. And things like fusion fueled vertical farming are still eventually on the table.

If you covered all land with nuclear powered greenhouses we could have enough food for a trillion people. Not that we should, but it's a thought exercise showing that food isn't the limiting factor for population. I'm really glad that we've found another limiter, because imagining life on an Earth with a trillion people.

I hope the solar system is someday home to a trillion people. We need more minds working on the problems the universe presents to us. If humans won’t step up to that challenge then maybe our silicon offspring will.

I used to have similar hopes, but I think our first priority must be increasing efficiency of research. Consider the transition to open access; it is still a minority of research effort so many researchers waste untold resources reinventing the wheel. Also the incentives to publish mean a lot of fields consist of people writing papers for the sake of writing papers, without much progress towards anything resembling novel ideas

Model code here: https://stockholmuniversity.app.box.com/s/uh7fjh52pvh7yx1mqf...

Interesting kind of model, I would be interested to see how it performs hindcasting. I don't know much about this type of modelling but I suspect it is much too simple to have any real predictive power.

i wonder how long before every living person has an ancestor who was a billionaire in 2023

What do you mean?

Presumably mass die-off with only a few billionaires and their nearest kin surviving in deep underground bunkers.

A billion dollars was a lot of money in those days

I would hazard a guess that the survivability (and likely the reproductive fitness) of the private security professionals of these billionaires is at least as high.

"private security professionals"

Why would they have any need for their billionaires after society collapses?

X-chromosomal Elon?

There are currently around 3000 billionaires out of 8 billion people, about 1 in 2 million. Assuming billionaires have an average number of children, the proportion of population who is descended from them must double every generation, regardless of overall birth rates. The factor of 2 million is about 2^21, so we need 21 generations. A generation is about 25 years. So our final answer is about 525 years from now, i.e. around 2550.

This assumes that age of death retains the same bounds as currently. If old age is cured before 2550 then someone not descended from a 2023 billionaire might live until the end of the universe.

do you think real estate is still a safe investment considering the projection for population drops?

Depends on location. If your real estate is in a place with liberal immigration policies and demand, then local birthrates are irrelevant.

Imagine being alive through peak humanity. Is it us? These sure are interesting times.

What data do they have that supports this argument? The consensus is for a peak a bit higher. Given that 6B, 7B, 8B were all hit at consistent/decreasing intervals of ~12 years, it would be surprising if the intervals didn’t get longer before suddenly stopping altogether

I do not understand this comment. The interval you are referring to is time, so barring extinction or the universe’s heat death, how could that stop?

I mean the intervals between population hitting a new billion (6B to 7B, 7B to 8B) They intervals have been getting shorter and shorter due to exponential growth. Obviously there will be a last such interval when population peaks (no 9B to 10B if we never hit 10B), but I would expect them to lengthen due to slowing growth rates (ex. 8 to 9 takes longer than 7 to 8) instead of the last interval being the shortest one (zoom from 7 to 8 at record speed and then never hit 9) I haven’t dived into specific rates and forecasts tho.

The article does state 8B to the peak will be 2022 to ~2050, which is longer than 12 years, although I disagree with your reasoning that the time to peak must be longer than the time from 7B to 8B. It all seems very arbitrary.

You need to factor in the age of the population too. As large parts of your total population gets old you can have a sudden reversal.

It’s not a simple function of time and population. Fertility rate varies by country and more specifically by economic achievement. Population isn’t evenly distributed in either of those categories. We saw rapid gains due to China and then India modernizing. Now they are declining and peaked and its Africa’s turn but Africa is a continent made up of many countries in various states of development or regression which makes it very difficult to predict. If we take the happy path and all goes well with each country continuing to improve then they will peak quickly having the advantages of modern technology and three advanced economies investing in them.

Just plain census and GDP data shows that the richer you are, the fewer children you have. As poor countries climb out of poverty, their birth rate drops. As rich countries get richer, their birth rate drops below population-sustaining levels.

http://tinyurl.com/Birth-rate-per-income

Yes, you are absolutely correct. This is exactly why the UN has predicted a slowing of population growth with an eventual peak of 10-11B in several decades.

However this article is suggesting a much more drastic slowing and much lower peak. I am interested in the evidence or assumptions that are different between these two forecasts.

UN projections have also been dropping over time:

https://ourworldindata.org/world-population-update-2022

> Its previous release projected that the world population would be around 10.88 billion in 2100 and would not yet have peaked.

> In this new release, the UN projects that the global population will peak before the end of the century – in 2086, at just over 10.4 billion people.

> There are several reasons for this earlier and lower peak. One is that the UN expects fertility rates to fall more quickly in low-income countries compared to previous revisions. It also expects less of a ‘rebound’ in fertility rates across high-income countries in the second half of the century.

>the richer you are, the fewer children you have

Not entirely true, there is a reverse-parabolic correlation [1] After certain income level, number of children per family increases.

Middle class is shooting itself in the foot economically by having children, that's why there's such correlation.

1. https://www.researchgate.net/figure/Number-of-children-top-h...

That's sort of fascinating. I mean is that an absolute or relative thing? If we were all as rich as Bill Gates would we all have more children? Or if we were all as rich as Bill Gates - but Gates in turn was wealthier still - would the number of children we and he had remain the same?

In my personal experience the rich have a fairly bimodal distribution. My middle class friends have 1 or 2 kids. Most of my rich friends have 0 or 4+. The big families skew the average.

Interesting question, I'd say both. The harder it is to stay in the middle class (by arbitrary standard of living) or "ascend" by incorporating in Ireland, the more hesitant people are regarding children. F.e. if middle class population % is big (like in Czechia or Sweden), there is higher fertility.

>Middle class is shooting itself in the foot economically by having children, that's why there's such correlation.

Middle class are the worst off for having kids, at least here in Europe.

  • The upper class can afford as many kids as they want, no problem.

  • The lower class gets tax breaks and subsidies from the state according to how many kids they have and how low their income is, the more money they get from the state, so they also have a lot of kids because every extra kid means a net monetary benefit.

  • The middle class gets the shaft as they bear the brunt of highest income tax brackets to fund the state coffers, and also get the lowest amounts of child subsidies because their income is considered good enough, so they're the ones having the least amount of kids.

>Contrary to public popular myths, the team found that population size is not the prime driver of exceeding planetary boundaries such as climate change. Rather, it is extremely high material footprint levels among the world’s richest 10% that is destabilising the planet.

“Humanity’s main problem is luxury carbon and biosphere consumption, not population. The places where population is rising fastest have extremely small environmental footprints per person compared with the places that reached peak population many decades ago.” said Jorgen Randers, one of leading modelers for Earth4All and co-author of The Limits to Growth.

Btw world's richest 10% among the world's adult population (~ 5.2bn) means a net worth of about only $140.000; defined as “the value of financial assets plus real assets (principally housing) owned by households, minus their debts.”[0]

So, Jørgen Randers talks - almost exclusively - about the middle class in developed nations.

If one follows the 90/10 distribution through:

The threshold in being included to the top 1% is at about $1.15m. Or seen from the $1m landmark there are about 62.5m adult millionaires in the world.

About 90% (55m adults) of those have wealth of $1-$5m.

9% (4.5m adults) between $5m-$10m.

This leaves us with 3m adults having a net worth of over $10m.

Following the same pattern again only about 10% of those have net worth of over $50m.

Entering the size of a small city: now, there are only about 260.000 UHNW (>$50m) worldwide left.

85.000 adults have a >$100m net worth.

In the end we are left with a big global village of 7000 adults with a net worth of >$500m.

If you look at the wealth pyramid the 1% tip holds 50% of the world's wealth. The top 1% is a universe in itself:

A country (1% of world's population e.g. Germany) of millionaires within a metropolis of mult-millionaires (>$10m) within a suburb of UHNW (>$50m) within a village of billionaires. We tribal humans are simply not equipped to deal with such orders of magnitude in a meaningful empathic way.

When I'm reading this article and in particular that statement I'm left to wonder: Well, he also could mean the top 10% (-1%); this rounding error is simply the global middle class (2 bn adults) the other 50% wealth.

It doesn't take much to figure out that in our current wealth distribution machine, half of the world's adult population are a rounding error (1% of wealth), too.

Those wealth numbers can be roughly equated to access to resources; and when entering UHNW territory: +giant disproportionate influence in setting global policies. Probably like in a small city, they all know each other.

[0]https://www.credit-suisse.com/about-us/en/reports-research/g...

Educate more girls as fast as possible.

Definitely a worthwhile goal. But could you explain how you think this relates to the population peaking below 9B in the 2050s?

IIRC advances in women's education and healthcare have historically correlated with sharp declines in birth rates in developing countries.

Tried and true birth rate reduction method

Women do not need a bachelor’s degree to learn how to not get pregnant.

The whole society needs to accept that women should have rights to birth control, and should have control of when and who they have sex with. And, of course, educated women become able to sell services/goods that allow them to be financially independent, so as to not be coercible.

This happens to correlate with a society where women are more educated, but due to differences in physical power, “educated” men have to be part of the equation.

With no evidence to offer I strongly suspect this is the biggest piece of it

>And, of course, educated women become able to sell services/goods that allow them to be financially independent, so as to not be coercible.

I do not see a reason to rank the causal factors, but I can point to a few societies where the women and men are “educated”, but the women lack the rights they have elsewhere (either legally or practically).

Have there been any societies in the past where women were allowed an education but men were not, because the reverse was common.

Probably not, but there are countries where women are allowed an education and still do not have the rights they should have. Which is alluded to by the fact that they are “allowed” an education in the first place.

> Women do not need a bachelor’s degree to learn how to not get pregnant.

That is because educated women might choose to pursue a career or have fewer kids, not because birth control is hard to understand.

Besides, empower women to do what they want with their life instead of being walking incubators.

This must be the most superficial comment I have ever read on HN.

I still maintain that the current (hopefully slowing) unprecedented industrial population explosion - it increased fourfold in just the last hundred years! - was orchestrated by empires to have enough bodies to throw into meatgrinders of total war.

There's too many people. This is insane. Why isn't everyone freaking out. Slow down.

You first.

Wouldn't you know it, I don't plan on having eleven children. I'd be glad to afford just a couple.

if, during the past, only the people that could afford children, had them, there would be no people today.

> orchestrated by empires

What does this mean? Birthrates were not higher in the last hundred years than previously, We just got better at keeping kids from dying. In fact these days governments are begging people to raise birthrates and failing quite spectacularly at doing so.

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