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

Monday, July 2, 2018

Overpopulation Problem? What Overpopulation Problem?

Some people seem to be horrified at the sight of these images. For me, it is more a sensation of melancholy. These masses of people can exist only for a brief moment in the history of humankind. Overpopulation is a problem that will solve itself rather quickly although, unfortunately, not without pain.

I keep reading more and more comments about overpopulation on the social media. It is not just an impression: the trend of increasing interest in population matters is visible in Google Trends. Still weak, but it is there.

It is puzzling how the question is returning. It had disappeared from the media after it had been popular in the 1970s, at the time of the first "The Limits to Growth" study. At that time, there were less than 4 billion people and that was viewed as a huge problem. Then, somehow, it became unfashionable to mention overpopulation, just as it became unfashionable to consider "The Limits to Growth" as anything more than a completely wrong study written by people not smarter than Chicken Little (it wasn't the case).

Now, with twice as many people - 7.6 billion humans - we see a return of the idea that - really - there may be a little problem of overpopulation. Humans are so many that they are appropriating a larger and larger fraction of the ecosystem. That means less and less space for other species which are, indeed, fast disappearing. When you read that, in a not too remote future, the only large animal left on the Earth will be the cow, well, that makes you think.

A specific streak of the discussion is that overpopulation is not just a problem, it is "the" problem. If we could reduce the number of humans, it is said, then all the other problems, pollution, global warming, resource depletion, would all become automatically much more manageable - if not completely solved. This opinion is often accompanied by statements that the reduction must be accomplished by fair and nonviolent means: voluntary birth control only. That doesn't prevent some people from accusing the "Greens" or the "global elites" of planning the extermination of most of humankind. Others see an evil plot in the growing population, accusing the powers that be - governments, religious organizations, the Illuminati, the gnomes of Zurich, or whatever - to be engaged in a global conspiracy aimed at hiding the dangers of overpopulation.

Personally, I am not too worried about human overpopulation, nor about these pretended evil conspiracies. Not that I think that there aren't too many people around. The point, I think, is that if today overpopulation is a problem, and it is, it will solve itself rather quickly (although not without pain). No need for evil elites plotting extermination, nor of well-intentioned activists teaching the poor how to use condoms. The system itself will cause the human population to collapse.

The current 7.6 billion people on the Earth are alive in a very special moment of human history. It had never happened before and it is unlikely that it will happen again the foreseeable future. So many people are alive today because there exists a sophisticated and incredibly complex system engaged in keeping them alive. The stupendous transportation system that carries food all over the world is powered by fossil energy and controlled by the financial and political system we call the "globalization." As long as fossil energy and globalization exist, people will be fed and population may continue growing.

But for how long? The whole system is under heavy strain because of depletion and pollution. Natural resources are more and more costly to produce while fighting pollution - also in the form of global warming - is becoming more and more expensive. A new major financial collapse will be sufficient to disrupt the transportation chain which ships food it all over the planet. Without this system, the food will rot where it is produced and the people at the other end of the chain will starve. It will be the Seneca Cliff of the whole system, including the human population.

There are other factors which may also work in the direction of reducing the human population. Think how interesting are the 400+ million tons of human flesh existing today for predators such as viruses, bacteria, and assorted parasites - we are their prey and we are rapidly becoming an abundant and easy prey. And there are more possibilities, from reduced fertility caused by heavy metal pollution to the old-fashioned, but always effective, large-scale wars. (1)

Recently, I published a paper on the Journal of Population and Sustainability where I looked for some historical examples of how populations (not just human ones) crashed down in the past. I found more than one reason that can lead to an abrupt collapse. An especially poignant example is that of the horse population in the US. It experienced a fast when the horses went down from some 27 million in 1920 to about 3 million in 1960. No one called for the extermination of horses but they had lost their economic value - replaced by machines -  and so they were not cared for anymore and not even allowed to reproduce. And that was the Seneca Cliff for horses.

Why not a similar cliff ahead for humans? They, too, have lost their economic value, being replaced by machines. You say that humans are not horses? Sure, but think about something: who decided the fate of horses? And who decides the fate of humans? You get my point, I guess. With humans rapidly becoming technologically obsolete, there would be no need to wait for an energy cliff to bring down civilization as a whole before seeing their numbers radically curtailed.

So, you may like to read my paper in the Journal of Population and Sustainability.

(1) I know that Paul Ehrlich cried wolf too early about population collapse, in 1968. Sure, that means population will keep growing forever, right?

(2) To explain this point, the fate of horses in the US 


  1. Cool post, I agree.

    The Pro Capite GDP is a quozient, at the top there's GDP at the bottom there's the population.

    It's quite easy to demostrate that in the next decades for Italy it won't be a positive GDP growth but a decreasing GDP because of climate change, financial wars, massive migrations, Punic Wars II. If the italian population will decline, the Pro Capite GDP will stay constant or it will decline with viscous degrowth. Because the fate of the numerator is unavoidable, in Italy less we are, better we stay:

    sorry, during the copypaste process, after pushing the icon "publish", damn! it desappeared "financial wars" from my comment. The sentence look with no logic, so Please cancel my first comment, and publish this one.

    1. Italian GDP is already dropping, no need to wait for big slow moving Godzillas like climate change. GDP peaked in 2008 and is weakly and only partly recovering at best, just in time for the next recession. It is now more a matter of how fast it continues to decline, not if.

      I very much doubt reductions in population will boost GDP, normally population is the last big variable to drop in difficult times. Economic activity is one of the first, that I know of.

    2. @ Yvan Roy
      That's true, the italian GDP in 2016 is a fake: if you look at the 2016 energy power consumption there was a decline of -3.1% and is not possibile to have a positive GDP in the same year, meanwhile there was so huge fail in energy power consumption!.

      I correlated the two variables with an easy linear regression, it's quite easy to discover that italian GDP growth 2016 is a fake made by ISTAT. The small growth of 2016 is totally out of range of the linear regression. I know my sample was short, but if you get a bigger sample, the mismatch correlation between energy power consumption and GDP growth, is much stronger, because italian economy in the distant past it was much dynamic and the positive regession was heavier.

      Another fake made by ISTAT, it is the value of the first quarter of italian GDP in 2017, the positive growth of italian GDP was a fake, ISTAT made it, to boost left party on showing positive stath infos to the mass media. The true is another story: there was no deflation in Italy in the first quater 2017, because in all Europe there was a small postive inflation: so you can't add data, you have to substract, to evaluate the Real GDP growth

      Since may 2017 the energy power consumption and italian GPD mouved in the same way.

      There's lot of fake policies, mass media don't talk about them because are stupid: another fake it was the 1 billion (more or less) of cash spent by italian government to Alitalia, becasue if Alitalia was on bankrupt it would have destroyed all good news in economy topics, during political election.

      The economic decline of Italy is structural, I totally agree, the italian bankrupt is a matter of time: I suggest to look (more or less) at the 31/10/2019

      In the long run, reduction of population in the italian penisula would help to face off the future massive crisis of the incoming years: less people will mean, less problem to solve: so less fresh water, less food, less energy...

    3. 65C02, -3.1% in one year is a big drop while not in a recession. I've also seen energy consumption used by mainstream economists to double check GDP numbers, such as with China recently because there is are doubts about the rather high official growth rate.

      Next strip away debt expansion and you are left very little real growth, the kind that would show in quality of life improvements for example.

      These things will all sort themselves out eventually. Physics always wins over simplistic assumptions.

      The next recession will cause things to lurch forward (downward?) one more step. It may not be very comfortable for many.

  2. I actually slightly disagree in regards to the horse analogy. At present there is huge population of aid and welfare recipients. At present solo mothers are held up as paragons of society yet have children with multiple partners.
    Also in the past nature would keep populations in check with the local environment and now we have an example of Tuvalu whose population has boomed yet will soon be under water.

    1. Correct. I explained my point better in the text.

  3. Someone will find a way to profit from the population collapse. The Really Big Short.

  4. I disagree with the horse comparison. Horse "overpopulation" did not solve itself, as you write about human overpopulation in the beginning of the essay.

    Humans decide how many horses get to survive, as well as how many other humans get to survive, but population collapse will definitely not happen because humans lose their "economic value" and get replaced by machines.

    If anything, as fossil fuels become harder to get, there will be less machines, and not more, and muscle power will replace mechanization, not the other way around.

    1. Yes, see my comment above. Your scenario might be the correct one: first we have the fuel cliff, and then the population cliff - just like in "The Limits to Growth". But we might also have the population cliff first - just like horses did a century ago.

  5. Tangential ... that's an interesting annual pattern in the Google Trends chart you posted. Anybody have any ideas why that pattern exists?

    1. A seasonal pattern. In summer, people don't seem to be searching for anything serious.

    2. I agree completely. Summer is when I go into the epicurian phase of my annual cycle. The sky is blue, the wine is cool, and the trails in the Columbia River Gorge beckon.

      The earth can probably maintain between one and two billion people in a sustainable manner. The population will reduce to below that level and then start building up. My scientific wild-ass guess (SWAG) is that the bottom will happen around between 2075 and 2150, depending on what form the reduction takes.

  6. Someone has already figured out how to profit from all of this misery. Just watch all of those "feed the starving children" ads on TV. If we actually do feed them they will reproduce even more people which will exponentially increase the starvation and thus the profits. I bet those linear thinking Wall Street geniuses see it as the next big and never-ending profit center. They are probably working on profiting from the upcoming water shortages too. They were a little too eager in Bolivia. Bechtel was trying to force the natives to pay for collecting rain water. The people forced them out. A massive mercenary army will be ready for them the next time around.

  7. There is a foul (but still mild) taste of lifeboat mentality above (as of 1:20 PM CDT US). People breed like rabbits so they and their progeny are responsible for their misery in an overpopulated world and hence have no right to climb aboard the lifeboats of the virtuous. I notice this attitude among my fellow US citizens. Typically, the people trying to board the lifeboat are people of locally unfashionable colors and/or features, who also buy filet mignon with food stamps funded by taxes paid by hard-working victims of misgovernment.

    When we have baptisms in my parish, the congregation repeats and renews their own baptismal vows. A good exercise. The one I have trouble with is to respect the human worth and dignity of every human being. Dunno why I keep trying.

    1. Very worth saying, please keep trying. To strengthen your point it os woth mentioning that overpopulation imo can only be stated if a population lives beyond its capacity to sustain itself, its carrying capacity.

      Well guess what wich population is the one that surpasses its carrying capacity by over 100%! If one considers overshoot as a measure for true overpopulation the USA is the most overpopulated nation in the world, followed by all the other industrial countries. Most south sahara african countries stll live well below their carrying capacity.

      IMHO true overpopulation is shown in this map:

    2. Immigration from poor, more sustainable lifestyles to rich less sustainable countries is aggravating this very issue you two are mentioning. Rich countries could be letting their populations decrease naturally over time, if they really cared about global warming and all that kind of thing.

      Also, when population management is mentioned, it is not always aimed at specific regions. There are simply to many people on the planet, overall, without running the risk of a major die-off.

  8. Concerning the disruption of food transportation: intuitions tells me, that people will curb every other exergy use when necessary to avoid hunger.
    We also see an extraordinary reduction in the number of children per woman all over the world, with the exception of subsaharan africa.
    Although it is self explaining, that population density is the most important single parameter of the concern we have, it is of no use to imagine a world with one billion people - it is a mere dream and the people who are there have a right to live and not suffer overly. We have to work whith the situation and means we have.

  9. Agree with your comment regarding Paul Ehrlich. The only thing he got wrong was the timing. And the human population crash. The global financial system is already primed for collapse, and when it goes, so will civilisation. It also struck me that there will be damned few survivors - because as you mention, once a few billion of us die off in relatively short shrift, the diseases of the past will come back big time, parasites, viruses and bacteria, and finish off most of the survivors (that have not starved - the main killer).
    To end on a more optimistic note, lovely weather we have had this summer, best since 1976.

  10. The ongoing heatwaves and droughts should give "civilisation" enough momentum to jump off the Seneca cliff.

  11. It is very strange that no one talks about the fact that birthrates are falling, and the more developed the country the lower the birthrate.



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)