Cassandra has moved. Ugo Bardi publishes now on a new site called "The Seneca Effect."

Thursday, October 25, 2018

Why is Overpopulation Ignored by the Media? The Reasons of a Historical Failure

Some people think there exists a conspiracy that prevents the media from ever mentioning the charged word, "overpopulation." Conspiracies do exist but, in this case, my impression is that population is such a charged issue simply because it has to do with the fact that we are all humans and discussing about reducing population touches some inner mechanisms of our psyche that we feel uncomfortable about.

But there is more to that: the real problem with overpopulation is that most decision makers lack the concept of "overshoot,"  a view that didn't exist in the study of social systems until Jay Forrester introduced it in the 1960s.If you don't understand overshoot, at best you can understand that there are limits to population, but you can't understand that population could exceed the limits and crash down ruinously with the deterioration of the agricultural system that feeds it.

The lack of a the concept of overshoot may well be what leads the concerned and the unconcerned to minimize the problem. Many people seem to think that the "demographic transition," the reduction in fertility observed in most rich nations of the world, will spread over all humankind and stabilize the world's population at a sustainable level without any need for governments to intervene to force lower birth rates.

Almost certainly, it is too late for that: we should have started decades ago. But only China implemented a serious policy birth control -- for the rest of the world it was a historical failure.

In the discussion, below, Bernard Gilland discusses the problems we will face in the attempt of stabilizing the human population mainly in terms of the degradation of the agricultural system in its dependence on non-sustainable resources. It is not the only problem, with climate change potentially able to do even more damage to agriculture. At the same time, the many young people in poor countries will push population onto a still growing trajectory. If these two tendencies, population growth and agricultural decline, crash against each other, the result might well be a Seneca Cliff for the world's human population.

A sustainable global population -and why we cannot achieve it

Guest Post by Bernard Gilland

In the period 1975 – 2018, world population increased at an average of 83 million per year, and reached 7.6 billion in 2018. The increase in 2017 was the difference between approximately 145 million births and 62 million deaths. Despite population growth, the global average daily food supply per person rose from 2440 kilocalories in 1975 to 2940 kilocalories in 2015 (1). However, over 800 million people are undernourished and 300 million adults are obese.

Cereals are the most important crops for food and feed; globally, 45 percent of the cereal production is consumed by humans, and 35 percent by livestock. The remainder is used for industrial purposes, including ethanol, beer, whisky and vodka. The rise in world cereal production since the 1960s is mainly due to two technological advances. The first was Haber-Bosch ammonia synthesis, in which atmospheric nitrogen is fixed as ammonia (containing 82 percent nitrogen) which plants utilize for protein formation. Production of Haber-Bosch ammonia began in 1913, but did not begin to rise rapidly until the 1960s. The second advance was the Green Revolution that began in the mid-1960s, after agronomist Norman Borlaug had bred varieties of dwarf wheat that give higher yields in response to heavier applications of nitrogen, phosphorus and potassium fertilizer, pesticides and irrigation. The breeding and use of semi-dwarf rice and hybrid maize paralleled that of wheat.

The most striking achievement of chemical agriculture is the maize yield in the U.S., which rose from 2.5 tonnes per hectare (40 bushels per acre) in 1950 to 11.0 tonnes per hectare (175 bushels per acre) in 2016. The global cereal yield rose from 2.81 tonnes per hectare in 1992-96 to 3.91 tonnes in 2012-16 (2). Linear extrapolation of the 1992 - 2016 yield trend (52.3 kg per hectare per year) gives a yield of 5.73 tonnes per hectare in 2050. If the population in 2050 is taken as 9.85 billion (3), and the harvested cereal area remains 718 million hectares (as in 2016), production per person in 2050 would be 420 kg, 10 percent above the 2016 level of 382 kg; the uncertainty is about 10 percent either way. Assuming that the global average cereal yield without using nitrogen fertilizer is 1.6 tonnes per hectare, and that fertilizer increases grain yield by 30 kg per kg nitrogen applied, the global average nitrogen application on cereal crops, 80 kg per hectare in 2015, would be approximately 140 kg per hectare. If the incremental yield-nitrogen ratio rises to 35 by 2050, the nitrogen application would be 120 kg per hectare.

The success of the Green Revolution created three major ecological problems:

1. Globally, about half the applied nitrogen is taken up by the crop plants; the remainder volatilizes in the form of ammonia and nitrous oxide (a powerful greenhouse gas) or leaches to groundwater, resulting in eutrophication (the formation of algae) in rivers, lakes and coastal waters; this creates “dead zones” in which fish cannot live.

2. Applying nitrogen, phosphorus and potassium fertilizer to crops changes the balance between these nutrients and those needed in small or trace amounts; the latter include calcium, sulphur, magnesium, iron, manganese, copper, zinc, cobalt, boron and selenium.

3. Approximately 40 percent of global irrigation water is obtained by pumping groundwater from tube wells; this has resulted in the depletion of aquifers and the lowering of groundwater levels, thereby contributing 0.4 mm to the global sea level rise of 3.4 mm per year (4).

As population growth increases the need for fertilizer, it follows that population reduction would ultimately solve the ecological problems. Unfortunately, human nature is such that global population reduction is not feasible. The reasons for this are given in the following.

In 1950, France had a population of 42 million and 20 million hectares of arable land, i.e. 2 persons per arable hectare. The nitrogen fertilizer application on cereals was negligible, and cereal production per person was about 400 kg per year, slightly higher than the present world average. If the ratio of population to arable land were 2 persons per hectare on the world’s 1.6 billion arable hectares, world population would be 3.2 billion. Reducing world population to this size would mean reducing the global average fertility rate (currently 2.5 children per woman) to 1.5 by 2050 and holding it at that level until 2200. The proportion of the population in the 65+ age-group would rise to 35 percent. Such a drastic change in the age distribution would mean raising the pensionable age to 70 years or more.

Adopting and enforcing a population limit for each country would be an insurmountable obstacle, as Charles Galton Darwin pointed out in 1952 (5). To lower the global average to 2 inhabitants per arable hectare, countries such as Canada, Russia, Australia and Argentina would not be required to reduce their populations, but would not be permitted to reach 2 inhabitants per arable hectare; they would be obliged to have a grain surplus for export to countries that need grain imports. China and India would each have to reduce its population to roughly 300 million; the combined population of the two countries would then be 20 percent of the world population instead of the present 35 percent (6). The relative population reductions in Japan and Egypt, which have 30 and 33 inhabitants per arable hectare respectively, would be much greater (6).

The population of China is projected to peak at 1.45 billion around 2030 and decline to one billion by 2100. This is partly a result of the so-called one-child policy launched in 1979 (in reality a 1.5-child policy). It was replaced by a two-child limit in 2016, but the fertility rate remains 1.6. Japan has a population of 126 million and a fertility rate of 1.4; the population is projected to decline to 102 million in 2050 and 60 million in 2100. These projected long-term declines are likely to be halted by pro-natalist policies based on the advice of growth-obsessed economists who believe that population decline results in a shortage of labour. A world population peak of at least 10 billion is almost inevitable, and this would make 70 percent of the world’s population dependent on Haber-Bosch ammonia. This is not sustainable, but there is no solution in sight. As a sustainable population cannot be attained by fertility decline alone, a mortality rise is highly probable. We can only guess when.

Bernard Gillan is an independent researcher with a degree in Engineering, based in Copenhagen, Denmark. He is the author of several papers on demography and population


1. FAOSTAT data.

2. World Bank data.

3. Population Reference Bureau. World population data sheet 2018.

4. Konikov, L.F. 2011. Contribution of global groundwater depletion since 1900 to sea-level rise. Geophysical Research Letters, 38; L17401.

5. Darwin, C.G. 1952. The next million years. Hart-Davis, London.

6. Lionos, T.P., A. Pseiridis. 2016. Sustainable welfare and optimum population size. Environment, Development and Sustainability, 18(6), 1679 - 1699. According to the authors, the optimum population of the world is 3.1 billion, and the populations (in millions) of the ten most populous countries are:

China 253, India 341, United States 326, Indonesia 88, Brazil 156, Pakistan 43, Nigeria 79, Bangladesh 17, Russia 249, Japan 9.2. The figure for Egypt is 7.4.


  1. "Almost certainly, it is too late for that: we should have started decades ago. But only China implemented a serious policy birth control -- for the rest of the world it was a historical failure."

    I still see the usual cliches about "female empowerment and education" being the silver bullet that will solve it all parroted all the time, even by people who should know much better. The problem is that even if we accept the assumption that those things will get the job done, they will do so on a time scale of several centuries. But the time scale on which the sustainability crisis has to be seriously dealt with is a few decades. Yet nobody seems to notice the glaring inconsistency between those things... Because talking about "female empowerment" scores you brownie points in today's political climate and most talking heads are not in it to solve anything, just to elevate their own social status.

    As is true about most other "solutions" to other aspects of the crisis -- what is proposed is invariably not even remotely sufficient to actually solve anything, but nobody bothers/wants to check what the numbers actually say... And again, one cannot escape the suspicion that very few people proclaiming to be concerned about the issues are actually concerned about the issues...

    1. I'd like to add some facts to this polemic.
      The decrease of fertility rate from 6 to 3 children took 20 years in Bangladesh and 10 years in Iran.

      Source (really worth reading!):

      I concede, that some african countries do pose a problem, as they have double the fertility of some asian countries with the same level of education of women. So the latte is no cure-it-all, but definitely contributing.

  2. HarryflashmanhigsonOctober 25, 2018 at 6:05 PM

    Give me the virus, I'll release it. TINA.

  3. As a sustainable population cannot be attained by fertility decline alone, a mortality rise is highly probable. We can only guess when.

    As to "when", I suggest that a "mortality rise" would best happen as soon as possible to relieve stress on the climate, water supplies, non-renewable resources and a litany of environmental ills too numerous to list here. The other advantage of an imminent die-off is that the sooner it happens, the fewer have to die.

    In addition to "when", the big unanswered question is "how" mortality will increase. My choice of horseman is Pestilence; it's quicker than Famine and certainly better than War if the war is nuclear. A nuclear winter would likely kill everyone and the majority of other land animals to boot. A pandemic could reduce the human population to carrying capacity and do no damage at all except to human population totals. Synthetic virus perhaps?

  4. As a father of 3 I am probably biased, but I think anti-natalists get causation backwards and do not think through the implications of
    mandating birth control.

    If population caused resource use, you'd expect to see the two to move in tandem. They do not.

    Exhibit 1 is of course China, the only large country who implemented anti-natalist policies, but is a major resource user and polluter despite (or thanks to?) decades of low fertility.

    Exhibit 2 is Japan, which essentially stopped having children. Japan's CO2 emissions spiked circa 2000-2014, exactly at the same time Japan
    entered ultra-low fertility territory.

    Exhibit 3 is Italy, where emissions peaked before the GFC and have been declining since. Emissions are now at about the 1998 level: in the same time, fertility went from ultra-low (around 1.2 births per woman) to just low (around 1.4).

    Exhibit 4 are all poor countries combined, who by and large have both high fertility rates and low CO2 emissions.

    I think Malthus had it right when he wrote that the abundance of resources causes population to grow, which in turn reduces
    abundance, thus constraining population through starvation. Probably Forrester gave an even more accurate account by adding overshoot, but that does not change the kernel of the reasoning: it is resource usage that drives population growth, not the other way around. So why should reducing population reduce resource usage?

    A look at a demand-and-supply graph should clarify this: your household might choose to consume less resources by having less children, thus lowering the price for other households who could then consume more resources, for example by having more children. Or buying more. Less people? Cheaper flights to New Zealand! Also called the rebound effect.

    It is of course resource extraction that drives population, and if you really want to reduce population, you should find a way to keep oil&coal in the ground, where they belong. We have no overpopulation problem: we have an overextraction problem.

    I agree that a mortality rise is highly probable. But I seriously doubt that we could prevent it by reducing our current population ceteris paribus.

    I apologize for using so much space for a comment, but I have other criticisms.

    For example that even China, an oppressive, autocratic regime, fell way short of the originally stated target of 700 million inhabitants. So what level of Orwellian paranoia do you think the world as a whole should adopt to control births effectively? How much would the surveillance apparatus cost, and what would its ecological footprint be? And this to fight the wrong cause of a problem that will probably solve itself once people run out of food?

    Or that it is not clear to me that societies would survive if having children were to become an oddity. What exactly would be the point of
    doing anything at all? Who would remember your life anyway?

    1. The alternatives "resource use is driving population growth" vs. "population growth is driving resource use" is clearly a much too simplified view. You cannot take a system with dozends or hundreds of interdependent variables, take two and then discuss, which of them comes first and which second. You definitely need a somewhat more complex underlying model!
      We can do two things:
      1. Find some plausible model,test it with the past experience and make "If A, then B with probability C." statements.
      2. Find some actions.
      That resource use is more or less equal to

      population number * resource use per capita

      cannot be denied. So what is determining resource use per capita? The industrialization level. So, given the latter, resource use is proportional to population.

      Arises the problem to find a way to a smaller population. Harsh state pressure as in China is one way. Change the attitude and tradition lines of a people is another way. Bangladesh is an example of this way more or less working. State paid family planning counsellors are constantly talking women and men into getting less children. The schools are hammering the equation "many children = poor children, few children = happy children" into the heads of their pupils.
      So yes, there are things that c a n be done about it.
      It also works the other way around. African heads of state insulting people, who have few children, as "lazy" are certainly counterproductive. Devaluing the the call for less children as neocolonial plot to keep Africa down shows, how you always can apply a view on a problem, that assuredly prevents its solution.

    2. >You definitely need a somewhat more complex underlying model!

      I admit to that, I am just an amateur. However, I am still unconvinced that suppressing natality, the Chinese way or the Bangladeshi one, really gets us anywhere (it can, of course, help local problems, but not global ones).

      I do not disagree when you say that:

      resource use = population number * resource use per capita

      But I think that resource use is more or less constant, and the other two factors are variables. I would rewrite the formula as:

      population = total resource use / resource use per capita

      If you try to reduce population locally, by force or indoctrination, it will increase somewhere else. If a few people consume less, others will consume more.

      The owners of the oil infrastructure will extract enough oil to pay for their variable costs. They will not so much adapt to price changes, just see how little the wild price swings post-GFC actually impacted volumes.

      So if people think that they can reduce oil extraction and resulting pollution by lowering demand, either by lowering the number of consumers or lowering the per capita consumption (solar panels, electric cars and so on), they are mistaken.

      The only thing that will slow down oil extraction is an increase in costs: we can wait for conventional oil to deplete so much, that drilling more is counter-economical. Or we can impose a global tax on oil extraction, at the source. Or we can prevent central banks from lowering interest rates and buying stocks of oil companies, to raise their capital costs.

      These are frankly unimaginably difficult targets, which could however work if implemented. Find a way to keep the oil in the ground, and population will decrease.

      But preventing people from having children will just shift consumption onto someone else.

  5. The topic is fraught with danger. To really enrage people, one might add to an already toxic mix the hypothesis that voluntary birth control relying on education logically leaves the world to the uneducable.

  6. The sustainability of such high levels of ammonia synthesis at at least from an energy point of view not unsustainable.
    Todays energy use for fertilizer production is in the order of magnitude of 1.2 % of total energy production. Even if we double or triple this and reduce world energy production considerably, we might up at 10 % or somewhat more. I have no doubt, that fertilizer production will get top priority above any other use of energy.
    Secondly, mankind can generate a lot of additional slack by reducing meat consumption, as this is very inefficient use of land.
    What I am somewhat more sceptical about are the fossil water resources. A millimeter more or less sea level doesn't matter, but nobody really knows, when all those aquifers will be depleted. This cannot easily be compensated for.


  7. It's interesting that Canada is mentioned as a country that does not need to reduce its average population. While this may be true for Canada, on average, I have been troubled by the situation for my home province of Ontario. To me, it is local food production and sustainability that is key, not some ephemeral global average; particularly if the global trade system breaks down as it could given that we may have already overshot energy resources (consider much has been 'pulled' from the future via debt).
    The province of Ontario long ago overshot its carrying capacity and relies very much on food imports. We have over 15 million residents and only 9 million acres of arable land (well over the 2 people per hectare suggested in this article). Of course, much of our arable land is given over to the agribusiness folly of growing GMO corn and soybean to feed the ethanol industry (about 70% of our land) and only about 3-5% of our land goes towards feeding our domestic population, while the remaining food we consume is imported (mostly from the US and Mexico).
    You would think, given this situation, Ontario citizens and its political class would be concerned. You would be wrong. Having just completed a province-wide municipal election I can assure anyone that the infinite growth mindset is alive and well here. Every politician's campaign rhetoric was about more. More services. More development. More housing. More economic growth. More. More. More.
    The (formally) small town I reside in has been growing in population at about a 10%/annum pace the past decade or more and has plans to continue to do so into the foreseeable future. Any local politician I have challenged on this madness simply abrogates their responsibility by stating it is a provincial mandate and their role is to accommodate and encourage it. And, of course, the province gives the same song and dance arguing that it is a federal mandate to grow the population via immigration. This approach simply adds greater and greater risk to our local food sustainability.
    Averages, especially global ones as used by this article, may make things appear more feasible and attainable, they leave out important local implications. With diminishing marginal utility hitting the fossil fuel industry (and pretty well every resource) to the extent it has been over the past few decades, I am not content to rely upon long-distance supply chains to guarantee my food supply; nor should anyone else. And limiting population expansion on a global level, while important from a wider perspective, does nothing to address local issues which may play a far more meaningful role in the not-to-distant-future when we race over the Seneca Cliff of resources that support global trade and food distribution.

  8. I am interested of what environment/energy knowledgeable people would reply to this very common objection to population reduction: a population smaller than present in western countries would not be able to sustain an aging population of retirees. To me it doesn't make any sense considering that on another page of the same paper one would read that the main problem in our society is young people unemployment. It is more probable that with a decreasing population natural resources, the real scarse resources nowadays, would automatically increase on a pro capita basis. Others would increase too, think of housing for example.

    1. There is a simple answer to this question -- this is an utterly trivial problem compared to what is at stake.

      People didn't retire at all until a century ago (and still don't in many parts of the world).

    2. At the same time we are wondering what the workforce will do with a large proportion of jobs being taken over by AI/robots.

    3. Yeah, of course, but does anybody read the daily paper? The argument which fuels France with its Payment of up to £1064 to couples having their third child and Italy with their "free farm-land at your 3rd child" is: who will pay for our children pension.
      Could somebody knowledgeable make an effort and write down a well articulated and documented article to reply to this argument which is obviously false?

  9. Part of the reason overpopulation is a "third rail" issue is the disparity between fertility rates in the developing nations and fertility rates in developed nations (and China). Because the rates are so much higher, say, in many African nations, calling for population reduction worldwide can have a perceived racist motivation.

    Since nobody wants to be perceived (even wrongly) as advocating race-based eugenics, it's easiest to steer clear of the issue entirely.

  10. Todays (2020) there's 7.7Billion of people on Earth.
    On 2050 there's 9.7Billion of people on Earth.

    Todays (2020) there's 1.09 Billion of african people.
    On 2050 there's 2.1 Billion of african people.

    +1.11 Billion of african people in 30 years.
    +2 Billion of people on Earth in 30years.
    Up to 55% of people on 2050 are african people 1.11/2=0.55.

    ONU always knew the problem of african demographic bomb, but ONU did nothing, and ONU did no put money to finance a demographic control policy on Africa. Even Chatolic Church knew the real situation on the ground in Africa from missionaries 's reports, but Catholic Church never ever asked a demographic control policy for Africa. ONU and Chatolic Church already wrote 20 years ago a destiny of war in the Mediterranean area, because of climate change and overpopulation.

    The question is: why did they do that?

  11. The problem is not too many people but too many of the wrong people.

  12. P.S. Not my opinion but everyone elses on the planet it seems.

  13. Read what human overpopulation does to animals:

  14. Critical Density

    Sordid pogroms from Rwanda to Algeria
    Overshadow floods, famines and malaria;
    Myriad teeth for a tooth, myriad eyes for an eye,
    And hordes of machete wielding ogres gone awry.
    They prance, they cry, they hack as victims writhe in gore,
    They then dance to enhance their yearnings to kill more.
    No doubt humanity has a propensity
    For massacring at some critical density!

    Boghos L. Artinian



Ugo Bardi is a member of the Club of Rome, faculty member of the University of Florence, and the author of "Extracted" (Chelsea Green 2014), "The Seneca Effect" (Springer 2017), and Before the Collapse (Springer 2019)