Delusional population projections lead us sleepwalking into catastrophe

Recent United Nations population projections paint a comforting picture of immanent population stabilization. But what if they are wrong? Global population growth does not appear to be slowing as quickly as UN demographers have predicted, making widespread famines and run-away climate change more likely in the coming decades.

By Jane O’Sullivan

The Elon Musks of this world think there can never be enough humans. When we fill up Earth, we will conquer the Universe! But most people think population growth is not a problem because it’s stopping soon anyway. Those “population alarmists” must be naïve, or motivated by racism. But what if growth is not stopping as soon as we think, and what if those extra numbers make it impossible to avoid widespread famines and run-away climate change?

In a newly published paper, I show how the UN projections have consistently underestimated global population growth this century. According to the UN’s 2022 data, there were 253 million more people on Earth in mid-2022 than the UN expected there would be in its projection from the year 2000. While they then estimated an annual increment under 80 million and falling, the actual increase has been roughly 90 million per year, with no sure sign of diminishing.

Each revision of the United Nations population projections has been higher than the previous version's projection. The estimate of current population always exceeds previous projection's estimates.
Figure 1. The UN’s estimate of world population, given in 2010, 2012, 2015, 2017, 2019 and 2022 revisions (solid pink line) and the projected population from each of those revisions (dashed blue lines). For full citations, see Jane O’Sullivan, Demographic Delusions: World Population Growth Is Exceeding Most Projections and Jeopardising Scenarios for Sustainable Futures.

There are several rival projections, the most widely known being the Wittgenstein Centre (the “shared socioeconomic pathways” or SSP series), Institute for Health Metrics and Evaluation (IHME) and the Stockholm Resilience Centre’s “Earth4All” project. All three anticipate far more rapid deceleration and lower peak population than does the UN. Hence, all are even further from reality.

Worryingly, these unrealistically low projections are being used in research efforts to model sustainable futures, which explore what it would take to avoid dangerous climate change and meet everyone’s needs within planetary limits for resource use and environmental damage. The SSP projections are particularly widely used in modelling. They then present sustainability as a viable (if highly challenging) possibility, when greater population numbers would breach environmental limits even under the most techno-optimist scenarios.

Figure 2. Projections of world population by the UN, Wittgenstein Centre (SSPs), IHME and Earth4All. For full citations, see Jane O’Sullivan, Demographic Delusions: World Population Growth Is Exceeding Most Projections and Jeopardising Scenarios for Sustainable Futures.

One reason for this underestimation is attributing fertility decline to socioeconomic circumstances, such as reducing infant mortality, improving girls’ education, urbanisation and industrialisation. None of the models assigns any importance to deliberate interventions such as voluntary family planning programs. While family size does correlate with each of those factors, all of the models treat fertility as the ‘dependent variable’, not considering how family planning programs might have contributed to lowering infant mortality, improving girls’ access to schooling and accelerating industrialisation and income growth.

The UN’s model is calibrated over the decades in which family planning programs were well supported and many countries had relatively rapid fertility transitions. However, since this support was withdrawn in the 1990s, fertility declines slowed globally and even reversed in a few countries. The UN doesn’t seem to have adjusted its calibration to account for this slow-down. On the contrary, it has recently recalibrated to increase the rate of future fertility decline, with no apparent evidence to back this change. Its rhetoric flatly denies that past family planning programs played any role at all, and is silent on its own projections’ poor record at predicting growth over the past two decades.

Regular readers of this blog might recall my critiques of each of these projections (here, here, here, here and here). In my most recent paper, I bring these together in the context of scenarios for sustainable futures. While few such studies have explored the influence of different population assumptions, those that did have found it impossible to achieve sustainable food systems and low enough emissions to avoid more than 2oC of global heating, no matter how rapidly and universally we change our production technologies and consumption behaviours, if the world population exceeds 10 billion. Yet, at this point it seems that only massive calamities will prevent the human population exceeding 10 billion.

Letting nature do the culling for us is not in anyone’s preferred playbook. Nobel Laureate Henry Kendall once said, “If we don’t halt population growth with justice and compassion, it will be done for us by nature, brutally and without pity—and will leave a ravaged world.”

If we go down in wars, famines and environmental disasters, we will take a great deal of biodiversity with us. Hungry people eat the roots of plants, the bark of trees, and anything that crawls, digs, swims or flies, if they can lay their hands on them. Protected areas become a meaningless concept. Hunger soon gives way to violence and failed states.

What would it take to avoid these calamities? The only answer is a much faster fall in birth rates in all high-fertility countries than is happening now. Such fast transitions have happened in the past, but only when contraception and small families were strongly promoted through active family planning programs.

It is an extraordinary tragedy that the global community shuns this opportunity, on the grounds that we are defending the poor from abominations like China’s one-child policy. We should instead be championing the great family planning successes such as in Thailand, Tunisia, Costa Rica, South Korea and Iran. Instead of emulating these successes, the high-fertility countries in Africa and elsewhere are being served an insipid and ineffectual reproductive health agenda, in denial of the harms wrought by population growth. It is supposedly centring women’s rights but effectively impedes women’s emancipation through lack of funding and political will for the services they need to avoid unwanted pregnancies, and through lack of a clear motive to challenge the patriarchal cultures that limit women’s roles to motherhood.

Population projections, like all complex modelling exercises, are rarely questioned because their details are difficult for the average person to fathom. However, models are only as good as their assumptions and data. The current crop of global population projections embed the myth that rapid fertility decline can be achieved through indirect socioeconomic drivers, together with the myth that direct promotion of contraception and small families is ineffective and incompatible with human rights.

Lulled by these fantasies, plans for achieving sustainable futures exclude population measures. We need a more integrated approach across the environmental and social justice agenda, which acknowledges the essential role of rapid population stabilisation in climate change mitigation, biodiversity protection, poverty reduction, food security and world peace. Unless we take a more proactive approach to ending population growth very soon, we will miss our last chance to avoid a hungry, hothouse world.

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17 thoughts on “Delusional population projections lead us sleepwalking into catastrophe

  1. A very sobering piece. The issue of misleading projections needs to be taken up urgently at the UN as well as among the modellers.

  2. The problem with the UN is that it’s not accountable for any failure. I’ve noticed this on other topics, and this is yet another example. States will not leave it so they don’t have that leverage even in theory, and they don’t seem to have power over its agencies unless it’s a very powerful country acting on some huge priority (e.g. China and the WHO), so they can make as many mistakes as they like and never answer for them.

  3. The author, Dr. Jane O’Sullivan, is both right and wrong. She is absolutely correct that accurate modeling is needed. However family planning (also known as voluntary population control) will not reduce the human population in time to prevent the collapse of civilization. The only action that possibly (and I emphasize the word “possibly”) could prevent the collapse of civilization is coercive population control. The latest prediction made by the UN is that the population will be between 8.9 and 12.4 billion by the year 2100, with the most likely number to be 10.4 billion. Reaching 10.4 billion would be a catastrophe for humanity. Therefore, by coercive population control I mean the immediate execution for crimes against humanity and stupidity of any person producing more than one child.

    1. If we can’t convince people that voluntary family planning would be a good thing, if we can’t even convince people that natural population decline in Europe or Japan is a good thing, how do you suppose we can convince anyone, even assuming you’re right, to implement coercive population control? You’re wasting your time with this argument.

    2. Comments like this bring opprobrium upon people trying to make a difference in the face of overwhelming odds. It is not helpful. Voluntary family planning is the only ethical way to address the climate/energy/population problem and if that fails then let nature take its course without adding more human savagery to the suffering.

      I think this comment should be removed.

  4. Global population probably will go down slowly, due to birth control, infertility, and other factors.  The problem is that fossil fuels and other minerals for “alternative” energy are finite.  So is fresh water.  So even if we go down to 4 billion, there is still going to be a big problem because just getting hold of food and water requires a lot of energy (including transportation) in our de-localized system of harvesting and distributing food and water.
    Actuaries, financial gurus, geologists, chemists, are all pointing this out to governments (who are taking stock, but not alerting the public yet as they do not want to cause panic).  Most of these scientists and mathematicians are men, but if you want a female one, the actuary Gail Tverberg is pretty good.  She does not court publicity, but her blog is called “Our Finite World”.  If you think I am gloomy, you ain’t seen nothing ……
    Gail focuses on the difficulty of getting enough Energy out of alternatives to replace Fossils – she does not seem to have researched the problems with extracting enough minerals to even operate alternative sources of energy in the first place.  
    The best option for this is geologist Simon Michaux – he is so good that he is constantly a guest on other people’s youtube channels (serious channels, not the ones hunting for an income through numbers of viewers).  He has two daughters – he says he tells them the truth but presents it as an opportunity for mankind to evolve, or rather “grow up”, at last.  Hitherto, all civilizations have been Growth-based – they have risen and fallen, but overall the picture has been one of constant Growth, turbo-charged after 1800 by the Industrial Revolution so that it has suddenly risen exponentially.  
    In this “bigger picture” scenario (which is undeniably accurate), the topic of contraception seems piddling to put it mildly,  
    However, attention to detail does matter, even if it bores big picture thinkers, and I should not be dismissive of individual attempts to limit consumption including having fewer babies (though it is more important to live simply, and one baby all too often results in more shopping, initially by relatives and later on by the baby itself once it can indulge on its own).  If everyone starts living very simply ALL AT ONCE, the global economy will crash of course – but it seems set to do this anyway, due to exhaustion of energy sources and also of waste disposal facilities, plus – above all – increasing cost of Energy however it is obtained. 
    Everything is so energy-intensive these days, including Medicine.  Small shops, cafes, and other small businesses are closing in droves now, just because they cannot afford their energy bills. Larger businesses are also struggling.  So are individual households.  I used to use only books, for both information and pleasure.  But since 2000 my use of electronic sources for both purposes has risen exponentially and I now hardly refer to books at all, though I am surrounded by them.  This is reflected in my electricity bills, which have risen but not yet exponentially.  What will happen when they DO rise exponentially?.  I have kept my books – but younger people have never had many in the first place, even schools have been dispensing with them. 
    As for cooking, washing, heating, lighting – the thought of going back to pre-1927 (when the UK grid was first rolled out on a nationwide basis) is not only horrifying but unworkable. The population was 38 million in 1921, in 2021 it was 68 million (plus illegals, so probably it has doubled to 76 million). And it consumes a lot more electricity per capita, at home and at work and at play and at school and in hospitals. So it does not just consume double the amount of electricity, of course – indeed I dread to think how much the number has risen by in Watts and Volts and I am not even going to try and find out. Plus there is all the hidden energy in imported stuff, grown or made using the electricity of other nations. If we went back to growing and making more ourselves …… well, clearly we do not have the Energy for this, or at least not at affordable prices. The whole world is kind of dependent on about 7 major oil producers, mainly Saudi and Russia. This is not going to work – and believe it or not, even Saudi and Russian supplies are finite.

  5. Valid points. But what’s tragic is that we never get national discussion–in the U.K. or the U.S.–on, perhaps, not rolling thing back to past lifestyles, but BUILDING A CLIMATE-CHANGE MENTALITY. I hear people alleging they are oh-so-worried about climate, but NOTHING in their lifestyle indicates real concern, such as porch lights on all night in my nearly NO-CRIME town!

    I’m of a generation where homes or businesses, back in the day, DID NOT LEAVE LIGHTS ON DAY AND NIGHT: if an appliance wasn’t in use, it was turned off, and millions of mega-watts of power (carbon) were not wasted on over-lamping of city streets and buildings, with hardly a city in the world having a DARK SKIES ORDINANCE today!

    One city, Tucson, Arizona, does, to protect its nearby Kitt Peak Observatory from light pollution. An ordinance, at first, opposed by their police department, which immediately became the ordinance’s primary supporter because the removal of shadows from OVER lamping, immediately increased dark places for the bad guys to hide!

    BTW, such ordinances save cities millions annually in utility costs because light isn’t going WASTED into the heavens but is keep exactly where it’s needed, plus consider the resulting lesser carbon emissions and in a pain-free way!

    And yet, as Biden, media, or whatever charlatan babble on about the “climate emergency,” there is nary a word about such “demand side” reductions, rather than endless focus on “green” (often not) energy sources–such as wind turbines that are killing THOUSANDS of migratory birds in New Mexico and the plains region! And that, as Old Joe EXPLODES THE POPULATION OF OURS THE HIGHEST PER-CAPITA CARBON NATION (2x that of China) on Earth via unfettered immigration. He’s either senile or corrupt!

    And thank you to the author for mentioning, duh, population. If the U.S. were still the 200 million on the first Earth Day and before the “environmental” community decided it was P.C. to invite in the world, rather than the 350 million we already approach, all of this would be SO MUCH EASIER. If there is a hereafter, Earth Day founder Sen. Gaylord Nelson, who founded the day solely to focus on the danger of U.S. population growth, is likely there saying very bad things about the Sierra Club’s sell out on immigration and population in return for a multi-million-dollar donation and an “environmental” community lacking the ETHICS OR WISDOM TO TALK ABOUT POPULATION!

  6. I spend a day at last April’s PAA meeting in New Orleans at a “member initiated meeting” organized by demographers from the University of Kinshasa in the DRC. They project doubling from 100 million to 200 million by 2050, similar to other populous African countries like Nigeria (230 to 460 m) and Kenya (53 to 106 m). The entire population of SSA was less than 300 M in 1950, but will be over 2 billion by 2050. A majority of Africans are subsistence farmers whose plots are becoming too small and worn out to support many children. Jacques Emina, head of the DRC demography program, reported that per capita incomes have dropped in DRC from $1200 to $500 per capita from 1990 to now, with 4 wars along the way. He speculated that poverty may drive the African transition as inability to feed large families may motivate women to avoid further births or higher infant mortality. Foreign aid may be essential as poor people cannot afford contraceptives. Moreover, many African governments are notably corrupt, so foreign aid is often stolen. Fertility transitions in at least 20 countries came from combinations of foreign aid (notably USAID) working to support local government family planning initiatives (notable progress in Mexico, Brazil, Bangladesh, etc.) So this combination of local head of government support and leadership with outside aid can help accomplish transitions. If Europeans don’t step up to this challenge the current numbers drowning in the Mediterranean will look tiny compared to the future flood of hundreds of millions of climate refugees. The Catholic Church bears huge responsibility for these predictable disasters, wars, famines, and plagues since it has a large role in health care in Africa. Changing Catholic teaching on birth control and abortion will be a key to African transitions. To Jane’s complaints about overreliance on questionable projections, the problem goes back to fundamental mistakes about the philosophy of social science. Humans are not objects subject only to effects of “variables” like education or income. We choose. We create norms collectively. We learn. Future fertility is contingent on human choices and actions. Unlike natural “laws” we enact laws. Passive approaches will mean higher populations. Policies and action could accomplish transitions in a couple of decades, faster than projections. As my grandma said, “That remains to be seen.” Discussion should stress contingency and uncertainty of outcomes pending future choices.

    1. All these right wing parties pretending to try to stop mass migration into Europe can’t say anything about family planning in Africa because it would be a full contradiction with their natalist policies at home. It’s a shame because that would really help in a win-win way.
      Left-wing parties don’t say anything either because it’s “racist”, besides, they are generally useless.
      Some countries, such as Spain, shoot back. Others, such as Italy, are totally overwhelmed. Others shut their frontiers but preach.
      Europe is doomed. African population projections are not just about Africa, at all.

      1. No matter what’s proposed, the subject of population control
        is unpopular. That’s why the politicians keep procrastinating.
        All leaders should have a job requirement to attend regular
        meetings of a spiritual recovery program, to learn to be more honest,
        like it or not.

      2. I agree: Eu should ban any no profit organization, Church in primis, that offers free food and helath care in overpopulated areas without asking back sterilization after 1st child…It may sound odd but it isgonna be made; real dela is if it is gonna be made within 2025 or in 2040.

  7. Max, interesting with the meeting in New Orleans – what did the demographers from DRC actually say about the situation? Regarding your thoughts about the Catholic church in Africa (SSA, Sub-Saharan Africa), with respect to fertility and overpopulation, the indigenous churches, the increasing charismatic churches (e.g. pentecostal) and particularly Islam pose the greatest threat to environment and people. See our review, including graphs and Appendices, here Note that catholics and protestants do not on average differ in fertility rates. The catholic church seems to be strong only in Gabon, Burundi and Rwanda (see Appendix). The early Christians, at least some, even tried to introduce contraception. The catholics introduced hospitals and built schools. But they mainly failed with respect to contraception, and new forms of Christianity are rapidly increasing. They do not care about the Pope. In addition, from about 1990 the US started to register religious organizations – especially evangelics – as new, accepted and recommeded form of overseas aid (both republicans and democrats). See “Faith in schools”, by Amy Stambach. Education is critical for norms, and in SSA many countries now trust international aid for new schools, while public ones are decresing, see e g “Learning morality, Ineqaulity, and faith” by H Dilger. In SSA, family planning would need to be a social movement to succeed, social groups and “groupishness” are critical, see “The righteous mind” by Jonathan Haidt. In the West, we saw a little bit in that direction when the paper on CO2 and “extra child” was published (downloaded 1000 times) but the authors just wrote about the West*. A social movement among the young based on that, although existing, is weak (a few will perhaps skip the extra child). And mainstream researchers attacked the senior author such that she now downplay high fertilty and overpopulation.

    * Actually, the original paper by Murtaugh and Shlax, that introduced the idea and method, included also the Third World in the calculations.

    1. “And mainstream researchers attacked the senior author such that she now downplay high fertilty and overpopulation.”
      Really? Do you have examples of this? It’s chilling.

  8. Hi Gaia,
    Here is a TOP review of a book the senior author published, after the paper. She has also in Swedish radio described how she was attacked by people, including academics I assume, about the findings and arguments in the “CO2 & and extra child” paper. The first author of the paper was a Master student (see link to paper in the review).

    1. Thanks. There was a Growth Busters podcast in which a university professor talked about how, when he asked his class to read a paper he had written on population, so that they could discuss it, they basically revolted against him. To the point he was physically scared going in (not that they would hurt him, but due to the psychological pressure of their judgement). And HE was the authority figure in this.
      We all know it: something is happening in the West and in academia, an insane amount of peer and institutional pressure to adhere to certain, not even principles, but attitudes and unchallenged assumptions.
      I find it very chilling.

      (Incidentally, this could be a good topic for this blog, even the specific story as it’s so telling)

  9. A major driving force for many of the world problems like the climate change is too many people, thus overpopulation. But the word (concept) “overpopulation” is banned from most “society controlled” bodies. It is even resistance to get articles about overpopulation accepted in the free press (a problem for TOP, which makes TOP very important). To describe this phenomenon (in Swedish with some focus on Swedish bodies) I had to use a channel with no censure

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