Occasional Paper: United Nations World Population Prospects, 2024

There’s indeed some room for optimism but in imho, unless we seriously curb consumerism, there is a very high chance, we’ll run into resource constraints of some sort. Judging by how many physical resources it took to get to the levels of consumption for just a small minority of humans and its accompanied degradation of the atmosphere+biosphere paired with shifting zones of habitation it might take more of a shift of mindset rather than mere changes of policy.

An underlying but questionable assumption here is that ten billion people would sustainable. The population curve can only take the shape depicted in the figure if there isn’t a series of massive global crises caused by resource (water, soil, carbon, etc.) over-consumption over the next few decades that leads to significant population loss through starvation, war, and disease as societies collapse and every growing parts of the world begins to look like Syria, Libya, and Somalia, not to mention the disruptions that the evacuation of Bangladesh, Florida, Denmark, and many other areas will cause. That ties in with the observation that predicting trends 60-70 years ahead is very difficult.

Point 2: 25% more seems manageable at first sight – if even eight billion is manageable. The fact that we have Earth overshoot day sometime around August or so each year indicates to me that anything above ca. five billion people is not sustainable, maybe less, and that sooner or later something will have to give.

Point 3: This isn’t a binary. We can move along at least three axes: how many of us there are, how wealthy and profligate we want to be on average, and how sustainably we produce our stuff. We can move along the second and third axis in an attempt to avert a crisis, but that doesn’t mean we shouldn’t also try to move along the first. Yes, population remaining constant, impoverishing ourselves will soften the crises ahead. But also, levels of wealth remaining constant, reducing our population will soften the crises ahead. Walk and chew gum at the same time.

Point 5: That has always struck me as a nonsense argument that only indicates that the person advancing it does not understand the concept of diminishing returns.

Point 6: See Earth overshoot day again. You can have (1) ten billion humans who are poor and miserable, or (2) humans being wealthy and comfortable but at most five billion of them if not fewer, or (3) ten billion humans being transiently wealthy and comfortable followed by global ecological and societal collapse. Pick one.

Brian,

Very puzzled by your first paragraph. Isn’t a world where population grows, or a world where population stagnates, also a world where “demographics that have large families will take over politically and socially”? That is mathematically always the case, and the necessity not to grow beyond carrying capacity is orthogonal to that observation.

But yes, I share your pessimism. I strongly doubt that people collectively will accept that they cannot consume a multiple of the resources that the Earth can provide us with sustainably. That is why any political party that suggests measures adequate to the severity of the crises we are facing is stuck at a maximum of 10% vote share, if that. My expectation is global ecological, societal, and population collapse within the next two centuries are politically unavoidable.

“With the very big exceptions of climate change and environmental degradation, at the global level pretty much everything has gotten better over the last 25 years, even while population has grown and grown.”

Well the first part is very much “apart from that Mrs Lincoln” isn’t it? As for the second, well it is true that on those kinds of measures life has got better, but over the same period the same forces that have brought us this progress have also made various forms of life more and more unviable from peasant smallholdings to high-street business to various artworlds, to (possibly!) liberal democracy. The working of many professionals have become more proletarianized over the same persiod. So farewell to the petty bourgeoisie, maybe we’ll miss them when they’re gone?

Carbon-equivalent gases continue to rise, while the other major environmental problems (deforestation, species loss, nitrogen overload …) are largely unaddressed and new ones (forever chemicals, micro-plastics … crowd in. So something more than a technical fix is needed – something along the lines of a change in human attitudes to consumption. Whatever the population curve, and whatever the projections 70-80 years out, most of these problems are persistent on very long time scales (by human standards). CO2 degrades over centuries or millennia, and the inertia of the climate system means that temperatures will keep rising for decades even after we reach zero emissions.
How do we get to a politics that takes centuries seriously? Because that’s where we need to go over the next few generations.

“Subsidizing something makes it cheaper not more expensive.”

If I was subsidizing energy generated by burning Rembrandt paintings, people would buy it, cheaply. But it still wouldn’t make Rembrandt-burning a cheap way to produce energy.

We all focus on the gruesome exceptions — the Afghanistans and Somalias — and ignore the fact that the average Chinese

Hmm I wonder what China did right
https://www.routledge.com/How-China-Escaped-Shock-Therapy-The-Market-Reform-Debate/Weber/p/book/9781032008493

“But at the global level, we are not headed for any massive world-wide crises in the near or medium term…”

Huh? What planet are you on?

Doug Muir,

I will admit that I have mixed time horizons a bit. I expect a gradual worsening of the situation with additional local collapses into failed states as resource overuse and global warming worsen, but it could well be that our equivalent to the end of the Western Roman Empire is as much as two centuries away. It takes a lot to collapse an empire. Then again, complex, as in complex society, is another word for fragile, and given the way our supply chains work, how many countries are unable to feed themselves without massive imports of grains, that various parts of the world will likely run out of ground- or glacial meltwater within decades, and that a few missed meals make people desperate, things could at a local level unwind much faster than we would like to acknowledge. And if there are enough such localities, things begin to add up.

I just don’t share the overall optimism. Two undeniable realities are, first, that we are living unsustainably, with carbon release in particular showing no signs of a sustained downward trajectory, and second, that few people are willing to vote for restrictions on their own comforts that may be required to achieve sustainability. One can predict a likely outcome from those two observations.

Your counterargument is that wealth has been increasing over recent decades, which I generally liken to a driver bragging about how fast they are driving towards the cliff, and that, surely, people will adapt. I think that is an enormous underestimation of the scale of the problem and over-estimation of people’s ability to adapt to heat waves so bad that the birds drop dead from the trees, to the disappearance of rivers and the drying out of wells, to soil erosion and salinisation, to the encroachment of ocean water onto many of the most densely populated areas, and to the sudden influx of millions of desperate climate refugees from one country over. You don’t just need to feed another two billion, you need to feed them just as crops are experiencing increased drought and heat stress.

I am certain that leaders of the Indus Valley Civilisation also thought they could adapt to crises before their rivers dried up. Today, we don’t even know how to decipher their writing, much less how they governed themselves. There is no reason to assume we are wiser or more resilient than they were. We have more technology, but that also means we will fall deeper and lose more, because we are each much more specialised and thus dependent on the complexity that we may struggle to maintain in a crisis.

Most statistical agencies are still defining “working age” as 15-64. It’s already more like 20-70 – the set of jobs that can usefully be done by a willing teenager is shrinking to zero and the set that wear you out physically is a lot smaller than it used to be. It’s true that lots of people still want to retire before age 70 and have earned enough to do so, but that’s only a problem of how society organizes itself, not the fundamental issue implied by “dependency ratios”.

Certainly must agree that more data both cross cultural and longitudinal is needed for a properly scholarly presentation for the notion. By academic standards, my suggestion the evidence available can’t refute the approach any more than it conclusively prove it, as of yet, can be dismissed, no doubt. But…

Being sympathetic to Marxism myself, I think of the birth control pill as a force of production. Peoples and states across the world and its cultures have been exploring its potential for decades now but it seems to me that this process still has not worked itself out (not that it can be finished any more than any history can.) Recent socioeconomic history in that sense is transitional. Drawing conclusions from that data set seems premature? (By the way, my conflation of petty bourgeoisie and labor aristocracy is not Marxist orthodoxy either, it just seems to me that the form it takes is the claim that “we” are all middle class, not workers. And all of us can acquire enough income to amass property and be “middle class” and it’s your fault if you don’t.)

Be that as it may, even in recent times, crises reveal any system’s dynamics. Even in modern states without birth control pills, birth rates tended to drop during wars, with a baby boom/Baby Boom after. The horrors of capitalist restoration in Russia and Ukraine led to a population drop according to what I have seen. It is unclear how this isn’t relevant data too.

Joseph Tainter’s The Collapse of Complex Societies is contested, but the thesis the complexity ultimately causes collapse hasn’t been refuted either, so far as I know. The Indus civilization from what I know was unusually egalitarian and that may have enabled its relatively longer period of adaptation before collapse. I think this is an implication of Tainter’s approach. (When I get to The Dawn of Everything perhaps I’ll be reading their take on Indus?)

The thing there is, on a world scale there is no single ruling class, no government, not even a central bank and currency (not even since 2008, It’s hard to see “complexity” in the way Tainter spoke of it, I think. In terms of extraction of resources by a ruling class causing hypertrophy of a ruling class whose apparatus cannot continue to deal with the complexity of their creation, it is hard to see how the world as a whole is absent a theory of imperialism.

But such theories are distinctly not widely accepted either, are they? Not in academia and at this moment it’s not even clear that BRICS+ work with such a notion of imperialism as THE irreconcilable enemy. Peaceful coexistence with imperialism is the professed goal. The approach seems to be more like anti-trust, an ideal of “fair” competition to be enforced by…somebody?

As to the collapse of simple societies? Peter Turchin offered a post https://peterturchin.com/the-collapse-of-simple-societies/ of interest, to me at least.
Simple societies do collapse. Here in the US, there are the prehistorical collapses, the Anasazi in the southwest and the Cahokia complex. (No, it is not customary for historians of indigenous societies to see this apocalypse as playing any role, but I think that is simply wrong, bad history.) There was recently popular news about the population collapse in Britain and the near total replacement by continental immigrants, revealed by DNA studies.

Elsewhere, the disappearance of Mayan civilization/urban society is notorious, but the Toltec or the predecessors of the Inka are other examples. The archaeological traces of advanced cultures in the Amazon seem to be real even if The Lost City of Zed ended in a mystical epiphany. In Africa, the disappearance of Meroe and Axum and the original Ghana are candidates I think. The cultural disappearance of the builders of Great Zimbabwe is incontestable in my opinion. Once the disappearance of the Angkor Wat civilization was equally well known?

Closely related I think is irrevocable decline with a more or less permanent population loss,. Central Asian civilizations once produced world leaders like Bukhara and Samarkand and Balkh, no more. I suppose the similar disappearance of leadership from Damascus and Baghdad is too much blamed on Islam to be noticed?

Sorry to have gone too much into background, rather than specifics, made worse by bad style. Harris spoke of these questions in much of his popularizations of anthropology, but perhaps the most accessible place is his book America Now. The first issue is the division between periods and place where children cost too much for the parents to keep their lifestyle without limiting their reproduction. The old joke is that sex is for the upper and lower classes, because the first can afford the consequences (children,) and the lower can’t afford anything else. It’s the middle classes who need to resist temptations. This crude approach suggests that many areas with currently high TFR are those where the costs of children appear for now to be

The second division is between those who can afford their children’s education and help them get started in their careers, especially the family career of their first home. The preliminary tests suggested @22, TFR vs. Gini; TFR vs. income levels; TFR vs. both inequality and growth, do not come close enough to measuring the real cost of children.
Obviously I personally can’t do this but that is the task in my judgment.

As to the notion the factors inducing the choice (at this point in history much more possible) mostly by “non-economic” reasons, it seems to me that crass considerations of cost condition most of them, are basic presuppositions that in general determine what value the choosers can even assign to their non-economic preferences. I’ve forgotten who suggested that the rich don’t have larger families. But is this even true? Monarchs who keep harems have had enormous families. The famous genetic studies of Genghis Khan suggest his “children” are an appreciable fraction of humanity.

Other monarchs commonly didn’t have (legitimate) children willy nilly precisely in order to simplify succession. Those who left unnamed bastard children don’t prove the thesis the rich don’t have more children but that more a valid case of “Absence of evidence isn’t evidence of absence.” Similarly the truly wealthy have an impetus to limit families in order to concentrate their wealth, essential to family competition with other rich people. They’re not all Elon Musk.

Again, sorry to be so prolix, can’t write well enough to be pitchy, much less witty, can only half do the job.

Least and last, for what it’s worth, neither Harris nor Turchin are Marxist. If anything they considered themselves scientific replacements for Marx, principled opponents. (And Tainter I gather is entirely innocent of such heresy.)

IOW, the Indus Valley example makes a stronger argument against collapse than for it. If a civilization whose idea of cutting edge technology was the mud brick could survive 200 years of bad weather, that probably bodes more well than otherwise.”

It’s also telling that we have to reach back over 1500 years for examples of any kind of general collapse of urbanized society–critically, to times and places where urbanized society was exceptional. It’s been argued that we can define a ‘Middle Ages’ in the eastern hemisphere as beginning at a turning point somewhere around 500-600 CE when urbanized societies mostly cease to undergo any episodes of permanent collapse like the fall of the Western Roman Empire. I think part of the reason is that even if an urbanized society were to completely collapse, by this point there were many others to move in and take its place. Even the Western Roman Empire–well, the explanation’s there in the name: it sustained cities in formerly less urbanized regions for hundreds of years, then lost the ability to do so, partly because the peoples they dominated adopted some of their technologies and social organization–a lot of the ‘fall’ is actually ‘barbarians’ asserting increasingly effective claims to being Roman. The parts of the empire with older histories of urbanization did not suffer this collapse. Basically, what’s fragile and/or prone to collapse is any kind of social organization that is too small and limited in scale. A well-placed comet strike or invasion might have stopped the industrial revolution in Britain in the late 18th c., for a while at least, but I don’t think any institution or organization of global importance today couldn’t be pretty quickly reconstituted if it were suddenly eliminated.

Our most urgent environmental challenge is to reduce net carbon dioxide (equivalent) emissions to zero (that is, by 100 per cent) by 2050. Looking at the graph, the range of uncertainty in population by that date is about 5 per cent (0.5 billion people). Decarbonising cement (7 per cent of emissions) or making reforestation more effective matter more than changes in this range.

Conclusion: population is an important environmental issue, but a secondary one.

An age ago Doug M. wrote:

“That said, the current worst-case scenario is roughly a two meter rise by 2100.”

Either Greenland or a big chunk of Antarctica falling into the sea would be a lot more than that. A lot. More like 5 to 7 meters. Meanwhile, every time Science has an article on Greenland or Antarctica, the story is that it’s melting/sliding “faster than anyone expected”. Every time.

My bet is we’ll see major climate-change induced disruptions within the next 25, not 75, years. Even if everyone reading this blog stopped driving and flying.

Agree mostly with Alex SL but would like to get back to the demographic projections.

You note that this projection predicts an earlier and lower population peak that the previous. I think the UN predictions have already been criticized for being biased in the direction of higher estimates. A recent study in the Lancet predicts a global TFR of 1.8 by 2050. Due to population inertia, population may still increase for a while beyond 2050 but hardly as long as 2080 (https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(24)00550-6/fulltext).

An earlier 2020 study also in the Lancet projected a peak in 2064 at 9·73 billion
(https://www.thelancet.com/article/S0140-6736(20)30677-2/fulltext; also https://en.wikipedia.org/wiki/Projections_of_population_growth#After_2050)

In many countries, birthrates have been in steep decline in the last few years, notably in the US and Europe but also Asia. China’s population is already contracting, earlier than generally expected. Estimated fertility rates of India, Brazil, Indonesia, Mexico, Philippines, Vietnam, Turkey, Iran are below already at or below replacement (these are among the top 20 by population).

I’m convinced that many more people in high fertility countries would use contraception if they had easy and reliable access so a lot will depend on whether that access improves in the next 10 or so years, especially in Africa. Fertility rates in these countries might fall faster than expected if the conditions are favorable.

This demographic development in my view is one glimmer of hope in dark times. Our societies in low fertility countries will certainly face new challenges (and the xenophobic hate now spreading like a virus throughout Europe and the US will make it very hard to deal with those challenges) but it will make the necessary transition to a decarbonized lower-consumption economy more feasible.

“In fact, the majority of the developing world probably has better access to contraception than the average American or European did circa 1950.”

Fun fact: all forms of contraception were completely illegal in France until 1968. Fom 1946 to 1964, TFR remained essentially unchanged at or just below 3. It then plummeted below replacement within just a decade.

TFR in Ruanda peaked at above 8 in 1978, a mindboggling number, and declined to currently 3.7, an amazing reduction (about 1 per decade). If the trend continues, replacement level will be reached by 2040. The transition from a society in which having 8 children was normal to one in which having 3-4 children is the social norm must have been tremendous. Surely access is not the only factor, cultural and economic factors play a decisive role – but access is a precondition for people making choices.

There are countries like Niger where fertility hardly decreased over the decades (currently about 7). Is access to contraception really not a factor? Not the only one obviously but it’s hard to believe that nobody would want to use contraceptives if they could.

“This argument is usually made by pro-natalists, who are usually conservatives. But that doesn’t mean it’s inherently wrong or stupid.”

No, it’s not. The reason it doesn’t mean anything when they make is that they’ve shown, time and time again, that they don’t want the problems solved (Trump, border; etc. ad infinitum and just one example) because more problems mean more desperate and disaffected people who are willing to succumb or submit to tyranny. (Especially when/if the problems prove to be intractable or are treated as such, or are slow-walked in such a fashion that over time they become intractable even though they didn’t start out that way, as in the case of climate change.)

I don’t want to pull this discussion off-topic, but I think bekabot raises a good point, which I understand as essentially that conservative pro-natalism is not intended to solve problems but to do something else.

I might suggest rewriting the sentence from the original post as “these are not consequentialist arguments, aimed at increasing people’s happiness, or even an orderly society, but something else — but that doesn’t mean the arguments are wrong or stupid,” and then ask whether this is also true?

One possibility is that conservative pro-natalists would be persuaded to change their policy positions by being shown how bad the consequences of their policies are. Another is that they would declare that they think those consequences are good. (I tend to agree with bekabot that they’d declare they think disorder is good; I don’t think this is a new thing, some kind of defensive reaction to us horrible liberals making them uncomfortable about their beliefs by existing or something.)

I think there are few pro-natalists on this thread, though.
Those aren’t the only possibilities — they might declare they have special knowledge that following their preferences, which they naturally call something else, will inevitably lead to a much better result — but they seem the most plausible ones.

„But at the global level, most people in the developing world do have access to contraception.“

Yes, I mentioned a bunch of developing countries with low TFRs. The countries with high fertility are often very traditionalist and patriarchal.

bekabot: I think I see what you’re saying. The people you’re describing would seemingly look at earthly disorder and say it doesn’t matter because they’ve redefined “orderly” to mean something supra-earthly. It probably becomes unhelpful to ask if they’re still consequentialists at that point.

It’s interesting that at that point the onus shifts to the person pointing to (earthly) evidence to understand the true meaning of true order, as the person defending “non-consequentialist” policies sees them. (What’s even more interesting is that this special meaning of “order” doesn’t become manifest at the beginning of the discussion, but only at this point.)

But as you pointed out in your earlier comment, if I understood it correctly, what they want is order in a private world for themselves, and disorder for others as an incentive to seek out someone to help them and/or tell them the conditions of moving into the private, orderly world.

@Peter T, where ‘quite some time’ = at least 50k years, yes.

David in Tokyo claims “every time Science has an article on Greenland or Antarctica, the story is that it’s melting/sliding “faster than anyone expected”. Every time.”

And yet, the very first paper I found in Science about Greenland ice was this one: https://www.science.org/doi/10.1126/science.ado5008
It very specifically says that the rate of melt in Greenland has been slower than expected.

You only get support for the doomer perspective if you ignore a significant amount of the research.

Peter T @43
“coupled with a gradual spread of disorder since the 80s”

Now what happened in the 80s I wonder? I know Reagan and Thatcher and the advent of what in Europe is called “neoliberalism”. The market is magic and solves all problems. How they told us that if the winners compensate the losers, then everybody is better off – but then never did the compensation bit.

engels@49 The problem with talking about the menace of “endless economic growth” is twofold. It presumes that growth is the problem, not capitalist growth. Even worse it tacitly presumes that capitalism can deliver endless growth absent crises and wars, a problem it shares with the paper. This approach allows, if it doesn’t compel, portraying the correct future as one with travel passes, sumptuary laws, food rationing, compulsory birth control (which must include forced abortion,) people required to train and fill pre-selected jobs. Or worse, it allows, if it doesn’t compel, population reduction, which is unlikely to be fair and promises to foster exterminism as a social strategy. The seemingly benign version, one committed to some sort of unspecifiable market reform, maybe supplemented by a dirigiste Green state…which is pretty much the standard reformist approach right now, extrapolated. Maybe on steroids?

If you conclude that capitalist growth cannot deliver the kind of life the wealthiest have now to all, that is an argument against capitalist growth. Simply arguing against growth just isn’t useful, in my opinion.

Well okay but actually existing socialist growth was also pretty environmentally disastrous if I’m not mistaken. I’m not calling for sumptuary laws (travel passes seem like a good idea ymmv) but I do think socialism ought to mean thinking (rationally and democratically) about how we as a society want to live rather than bigger better faster more.

steven t johnson,

Yes, obviously the island it is an analogy to the entire planet. The problem is that people assume we can do some unspecified efficiency gains or innovation to make the limited resource base of the world magically infinite, whereas they easily intuit that an island is an island and has limited resources.

And, yes, part of my point is that markets and capitalism overuse resources because consumers want to overuse resources. Unless you have a 1980s cartoon villain model of capitalists, sitting in their office towers cackling over how they poison the planet by running poison factories at a loss, you must realise that they sell cars because people buy cars, they sell flights because people want to fly, and they sell cheese in convenient plastic packaging because few consumers are willing to take it in an unmarked paper wrapper instead. Talk to a few people outside your bubble to understand their purchasing decisions, and consider the idea that “for profit” is, under a market economy, exactly the same as “because that is what the buyers want”, as, again, the only alternative is running poison factories at a loss for the evulz, i.e., no profit. This is our reality, as upsetting as it is.

Plastic packaging for food is not just convenient it’s also hygienic. Imputing to people in general the most trivial motive possible for perpetrating a (dubiously) evil act like buying cheese wrapped in plastic is odd. Why not pick a stronger, less ambiguous example of the evil intent of the greedy consumers who rule the economy? Private jets, superyachts and luxury post-apocalypse bunkers come to my mind. Given how much of the economy is companies buying goods from other companies to create products and services, I’m not sure it’s very helpful to focus on the bubble around the individual consumer.

Where I live, I could buy cheese wrapped in paper, assuming I can get there before the deli is closed, hoping it won’t be a long wait, assuming I’m willing to pay the higher price. The deli is usually understaffed, so the wait can be surprisingly long. The visit should be timed so that the cheese isn’t sitting in a (often hot) car for too long, incidentally. But strangely enough I’m not sure whether the trees killed to make paper and don’t take up atmospheric carbon dioxide anymore are in the long run worse than the locking up of carbon in plastic? Maybe doing away with paper bags for groceries turns out to be a good idea? On the other hand, maybe plastic wrapped cheese should be priced higher than paper wrapped deli cheese? The problem there of course is that pricing is not under the consumer’s individual control.

The clause “the only alternative is running poison factories at a loss for the evulz, i.e., no profit,” suggests to me the problem is capitalist growth, not growth. I suppose I should point out that capitalist world economy has generated quite a few periods of diminished consumption, relatively long periods of slow growth and “best’ of all, huge portions of the population saved from sin by poverty (everywhere actually, though mostly in the neocolonial world by far.) The logical conclusion, that capitalism has some saving graces, doesn’t strike me as anti-capitalist. Also, I’m not sure that attacking consumption, praising asceticism, is quite as just a critique of humanity as apparently conceived.

That’s what attacking growth in general leads to, I think. It’s a little like religion I suppose, some believers often simply refuse to accept the logical implications, stopping in revulsion when others are more consistent regardless of human costs? The thing is, I don’t think religious organization actually do can be justly dismissed as merely the personal preferences of the congregation writ large. This is even more true since so much religion is basically inherited from family, family friends and social surroundings. An undifferentiated attack on growth, rather than on capitalist growth, seems to me to work out in the end in much the same way.

I’m not going to respond to Steven’s claims about “capitalist vs socialist growth” because I can’t begin to understand them.

Doug M.,

I cannot speak for engels, and yes, you did mention climate change, as an aside to quickly dismiss.

But I assume you must see the problem with your position:

If the average human is now “significantly richer, healthier, better fed, better clothed, better housed, better educated, and likely to live longer than the average human of the 1990s” BECAUSE (!!!) we are using roughly 1.5 times as many miscellaneous resources as the planet can sustainably supply, cf. Earth overshoot day, and infinity times as many fossil fuels as we can use sustainably, and you expect 25% more people to be exactly as prosperous for an implied resource overuse of 1.5 x 1.25 = 1.875 times as much as the planet can sustainably supply, then that prosperity is maybe not entirely something to be proud of? As mentioned before, I liken it to bragging about how amazingly fast we are driving, just look at our speed, isn’t this an awesome car? … while heading towards a cliff.

Now, maybe that same level of prosperity can be achieved sustainably. But right now, it demonstrably isn’t. That limits my optimism when considering that we need it to be achieved for another two billion people on top of that.