What you should know – but didn’t know to ask – about overshoot and the ‘population question’

William Rees explores the nature of humanity’s relationship with energy and the ecosphere, and reaches the unsettling conclusion that a population ‘correction’ is in the offing.

By William Rees

What would you think if someone called you out as a ‘dissipative structure’? Or better, claimed that you were a ‘thermodynamically far-from-equilibrium dissipative structure’? Chances are, you wouldn’t know whether to be offended or to ready yourself to accept congratulations—not many people have ever heard the term ‘dissipative structure.’

This is unfortunate because you actually are a dissipative structure—in fact, the entire human enterprise acts as a single massive dissipative structure. And, it turns out, understanding the workings of dissipative structures shines a whole new light on human ecological overshoot including global heating.

This is just one of the novel arguments in a new paper on the human ecology of overshoot in which I explain why a major population ‘correction’ in this century is inevitable. Simply put, overshoot means that there are too many people consuming and polluting too much; we are using the living Earth faster than ecosystems can regenerate. Thus, the purpose of the article was to make the case, on novel grounds, that: a) the sheer number of humans and the scale of economic activity are undermining the functional integrity of the ecosphere and; b) left unattended, this reality will precipitate a global economic and population contraction – i.e., civilizational collapse—later in this century. The following outlines the core of my argument.

A rather unsettling premise of the piece is that the human eco-predicament is, in many respects, wholly ‘natural’, the product of human evolutionary success gone awry. Innate expansionist behaviours that were advantageous in Paleolithic (pre-agricultural) environments have become maladaptive in today’s globalized industrialized environment. Why is this significant? Because society seems unwilling to recognize that H. sapiens is a still-evolving species subject to the same natural laws and forces affecting the evolution of all living organisms. It is entirely conceivable for modern civilization to be ‘selected out’ by an increasingly hostile environment of our own making. Policies and programs that attempt to ‘fix’ overshoot without attempting to override humanity’s now destructive expansionist tendencies are doomed to fail.

Which brings us back to ‘dissipative structures’—just what are they and where do they fit in? A dissipative structure is a self-producing system that develops and grows by extracting useful energy/matter from its environment and ‘dissipating’ it back into that environment as useless waste. (Isn’t that what your body does?) Dissipative structures form spontaneously in the natural world in response to concentrations or steep gradients of energy/matter. Indeed (and this is important), a dissipative structure can persist only as long as the energy gradient/concentration exists.

I now have to introduce a somewhat peculiar characteristic of human beings. People tend to ‘socially construct’ their own realities—religious doctrines, economic models, political ideologies, scientific theories, etc.—and then live out of their constructs as if they were real. Obviously, a social construct is valid or true only to the extent that it faithfully reflects any aspect of biophysical reality that it purports to represent.

From this perspective, neoliberal economics—the brand of economics currently running the world—is a problematically quirky social construct. Neoliberal models start from the assumptions that the economy and ‘the environment’ are separate systems and that human ingenuity (i.e., technology) can substitute for any product or process of nature. (They certainly make no reference to dissipative structures.) It is an easy leap from the neoliberal paradigm for the world to believe in the perpetual growth of the human enterprise abetted by continuously advancing technology.

But what if the neoliberal construct is totally wrong-headed? What if the human enterprise, far from floating in splendid isolation, is actually a fully-contained, wholly-dependent, growing subsystem of the non-growing ecosphere, as ecological economist Herman Daly consistently argued? Suddenly, the concept of dissipative structures takes on ominous meaning.

Ecologists recognize that living systems exist in nested hierarchies of dissipative structures (picture Russian Matryoshka dolls). Each sub-system in the hierarchy self-organizes and grows by extracting available energy and matter from concentrations in its host ‘environment’ one level up. It processes this useful energy/matter internally to produce and maintain its own complex structure/function and exports—dissipates—useless, degraded energy and material wastes back into its host.

Photo credit: Didssph

If something is fully dissipated, it is completely disordered; there are no concentrations or gradients, nothing can happen. Physicists refer to this as a state of maximum entropy. All things in nature tend to become more randomly ordered (increase in entropy) unless a source of energy is used to reverse this trend. But this energy always comes from the dissipation of another thing, such as the sun gradually burning itself out, or the food we digest. If the degree of disorder is referred to as entropy, then ‘negentropy’ denotes the degree of order. In effect, living entities (cells, individuals, species, ecosystems) raise themselves from static, disordered near equilibrium states to highly-ordered, functional far-from-equilibrium states but can do so only at the expense of increasing ‘global’ entropy, particularly the entropy of their immediate host systems.

The ecosphere is the highest level in the hierarchy with which we need be concerned—it is the mother of Earthly dissipative structures. The ecosphere produces and maintains itself through photosynthesis by assimilating high-grade solar radiation (negentropy) and by continuously recycling all essential elements and trace nutrients required by its constituent species. In the process, the ecosphere dissipates an equivalent quantity of low grade infra-red radiation (entropy) back into space. While this increases the disorder of its host—the solar system and universe—the impact is negligible.

Not so lower in the hierarchy. Like the ecosphere, the human enterprise is a self-organizing far-from-equilibrium dissipative structure. However, while the ecosphere evolves and maintains itself by ‘feeding’ on an essentially unlimited extra-terrestrial energy source, the sun, and by continuously recycling Earthly matter, the human enterprise grows and maintains itself by ‘feeding’ on the rest of the finite ecosphere and ejecting degraded wastes back into it. This means there are limits to growth: beyond a certain point, the human enterprise can increase in size, internal order and function only by depleting, polluting and otherwise disordering the ecosphere.

Far-from-equilibrium thermodynamics thus provides a simple two-pronged criterion for global sustainability: humanity cannot persistently consume and dissipate more biomass energy/matter (negentropy) than the ecosphere produces, nor generate more waste (entropy) than nature can assimilate (with a generous allowance for the needs of thousands of other consumer species with whom we share the planet).

Is it not clear enough from the above that the neoliberal mantra of perpetual economic growth is inherently pathological? The increasingly demanding human enterprise is functionally positioned to consume the ecosphere from within. Indeed, the accelerating pace of human-induced global ecological change suggests that humanity has already become dangerously parasitic on its planetary host. The increase in Earthly entropy—greenhouse gas accumulations, plunging biodiversity, land/soil degradation, pollution of everything, etc.— is anything but negligible.

Figure 2 from the paper. GDP is proportional to oil consumption (Log scales). Graph courtesy of Arthur Berman.

Humanity only recently transitioned to playing the maggot to Earth’s apple. With the industrial revolution, humans began seriously to dissipate enormous stocks of fossilized carbon energy—coal, petroleum and natural gas—that had taken tens of millions of years to accumulate. The 1400-fold increase in fossil energy use since just the early 1800s enabled a one hundred-fold increase in real gross world product, a 13-fold uptick in average per capita income (consumption) and provided the food and material resources needed to support an increase in the human population from one to eight billion. It took 250,000 years for anatomically modern humans to reach that first billion but only 210 years—1/1190th as much time—to add seven billion more! Economic and population growth rates that recent generations take to be the norm actually characterize the most anomalous period in human evolutionary history.

The fossil-fueled explosion of the human enterprise is completely consistent with another biophysical concept that almost no one has ever heard of, the maximum power principle (MPP). According to MPP, natural selection favours systems that evolve in ways that maximize their energy intake and power output (i.e., useful energy transformation) for self-maintenance, growth and reproduction. By drawing on a vast supply of ‘extra-somatic’ (i.e., ‘out-of-body’) fossil energy, humanity proved itself an unmatched competitor and the most materially successful vertebrate species ever to walk the earth. Human made stuff (‘anthropogenic mass’) now exceeds the mass of all living biomass on the planet.

But we have a problem. Our success is killing us. The human enterprise is a dissipative structure in overshoot; the production and maintenance of all that ‘anthropogenic mass’ has been at the expense of the entropic degradation of the ecosphere and essential life-support functions. This, in turn, puts humanity between an ominously foreboding rock and a horrific-to-contemplate hard place. The greatest dissipative by-product of burning fossil fuels is carbon dioxide, the major source of anthropogenic climate forcing. Thus, if the world community maintains its growth trajectory and reliance on fossil fuels—which seems to be our default position—people everywhere will suffer some combination of accelerating global heating; marine acidification; runaway biodiversity loss; catastrophic wild-fires, floods and droughts; spreading deserts; crop failures; local famines; collapsed economies; massive unemployment; abandoned cities; mass migrations; civil discord and possible geopolitical turmoil. On the other hand, if we abandon fossil fuels to avoid climate chaos in the absence of adequate substitutes—there are none—the world will suffer energy and other resource shortages; crumbling transportation systems; broken supply lines; shrunken economies; massive unemployment; crop failures; local (possibly global) food shortages; mass migrations; civil discord and possible geopolitical turmoil—and we will still suffer decades of climate disruption. In simplest terms, with abundant energy and continued growth, we will destroy the ecosphere and collapse; with insufficient energy the modern human enterprise must also collapse. Take your pick.

Now you know why a global economic contraction cannot be averted and will almost certainly be accompanied by a major human population ‘correction’. Informed estimates put the long-term carrying capacity of Earth at as few as 100 million to as many as three billion people.

For all the data and details, check out my paper.

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23 thoughts on “What you should know – but didn’t know to ask – about overshoot and the ‘population question’

  1. Agree with all this, but wouldn’t have brought in the entropy concept, as it confuses people when energy in verses energy out is the essential concept to grasp, and still brings out the relationship between GDP and climate change.
    As it happens, I commented about this to a ‘Real-World Economics Blog’ piece on the unreality of economic models and ‘Nobel Prizes’ for making them more and more unintelligible. I suggested an ‘Albatross Prize’ for the countries with the highest GDP, instead.

    Here’s my comment:

    “More fundamentally still: do any of the models even establish what is the ‘goal’ of economic theory?

    If it is simply to maintain a nation at the top of a league table of states consuming the most at the fastest rate, then GDP is actually a measure of the contribution of each nation to the destabilisation of the Earth’s life support systems, and its goal can only be the extinction of the human race itself. Already, people need cooling suits to survive outdoors away from their air conditioning, and families are found dead when their AC fails, or they forget to allow for the heat their muscles create when they walk back up a hill they just walked down in the sunshine!

    The ‘badge of honour’ that is proudly worn by the nation with the highest GDP needs to be replaced with an ‘albatross of shame’. Could someone out there make an actual award medal with that design: To be awarded to the nations who claim to be trying to combat climate change but are given away by their rising GDP?

    To save our world and us, we need to put the models in reverse and learn how to feed ourselves whilst lowering our overall consumption and turning ‘economics’ back into oeconomics, as a part of the overall oecological balance, synchronised with the Earth’s own feedback and control sysyems, that our pursuit of GDP for vain pride’s sake, has, very seriously, damaged so badly that the temperature has actually began to rise despite the myriad of natural controls that were working perfectly to hold it in our ‘Goldilocks Zone’ before we began burning fossil fuels faster than Nature can reabsorb them.

    Rising GDP is a symbol of deliberate and reckless sabotage of our life support systems. We need a real Nobel Prize for whoever can bring it down closest to net zero.”


    I also often try to point out the difference between heat energy and temperature. The concentration on thermometer watching as the main way to convince people that global warming was real, even though actual climate change was very clearly happening all around as an infinitely superior indicator than the very hard to measure average temperature rises, that *can only begin when the planets thermostatic feedback and air conditioning systems are unable to cope and may be irreparably broken*. This unfortunate choice of indicator, over obviously retreating glaciers and increasingly violent storms, is likely the biggest mistake in all of (he history of science. (I tried for decades to get scientists in the media to explain this, but not one bothered to even reply.)

    Good to see papers like this appearing at last.

    Steve Hawkins

    1. Steve, I think that “GDP is actually [the most accurate] measure [we have] of the contribution of each nation to the destabilisation of the Earth’s life support systems.” What other single number does a better job of quantifying the demands and harms each nation makes on our home planet?

    2. Steve, you write: “Agree with all this, but wouldn’t have brought in the entropy concept, as it confuses people when energy in verses energy out is the essential concept to grasp.”
      Actually, this isn’t the only or even the most important concept to grasp. Humans use the ‘energy in’ to (over)exploit the ecosphere depleting/dissipating concentrated deposits of everything from soils, through fish stocks and thousands of species of plants and animals, to rare earths and fossil fuels themselves. In the process, we generate prodigious quantities of often toxic waste which accumulates in everything from the atmosphere (e.g. carbon dioxide) to our food supplies (detectable quantities of hundreds of artificial chemicals) and ultimately our bodies and the bodies of other organisms. In short, we are steadily disordering (increasing the entropy of) the ecosphere and interfering with the functioning of life-support functions. This is ultimately a terminal process.

  2. I agree with all of this (although I must admit I don’t understand thermodynamics), but I think that the conclusion that collapse will happen one way or the other plays into the rhetoric a lot of people seem to love: “nature will take care of us”, which translates as: “I don’t have to actually do anything.”
    I’d be better that we at least tried to course-correct as much as possible and avoid the worse outcome, for our sake and that of the planet too. There is a lot that can be done, and natural population shrinkage in many countries is a hopeful sign.

  3. We keep reading stuff like this: https://www.aljazeera.com/features/2023/8/29/is-a-global-food-crisis-the-new-normal
    Overpopulation, overconsumption and over reliance on imports are never mentioned. The solutions suggested always involve doubling down on business as usual.
    Interesting that “ending hunger” is a “sustainable development” goal. It’s good to end hunger, but there’s nothing inherently sustainable about it. Especially when you are tasked with reducing hunger for an ever-increasing number of people.

    1. Gaia, couldn’t agree more. It makes a certain amount of sense, however; when people are facing existential threats like hunger or lack of shelter, they tend to grasp for an immediate solution from the systems that they know. But I think more and more people are understanding that these problems stem from overshoot, and are willing to consider scaling back our numbers and demands. I hope so, anyway!

      1. I wasn’t suggesting starving people shouldn’t be fed, or want to be fed! But if you’re writing articles for Al Jazeera or making videos for international broadcasting corporations or working for the UN, you’re probably doing alright at the moment and can and should think clearly about why we are in this situation exactly.

  4. I think to conventional (religious) thinking the Earth is here for us. Our gods will provide what is necessary. This has been our way of thinking for thousands of years and, even thought studies like this are irrefutable (I learned a new word which applies here, apodictic), the concept is beyond the average person capability of grasping. Unfortunately, one critical resource is education.

    1. There are a lot of religions that aren’t like this, that treat nature and its inhabitants as sacred and teach about limits. Unfortunately, peoples and cultures who have these kinds of religions tend to be small in terms of numbers and technology, and are overrun by more powerful human groups with different mindsets, who think their power proves that they’re right. It’s happened so many times before and it’s happening today.

      1. Well said Gaia. The Old Testament is a poetic version of the divinely inspired William Rees’s many writings, recording Limit after Limit to Growth being reached by one small nation (Ancient Israel) with disastrous consequences – yet these Limits were perforce regional, not planetary, from 1000 B.C. to whatever date is ascribed to the last doom-laden book of the OT.. Yes I know Rees is not enthusiastic about Religion – but IMO it is the abuse and misuse of truthful ancient texts that he does not like. Everyone abuses the OT, by distorting it or simply censoring great chunks of it that do not suit the Growth’n Progress agenda. Both OT and NT predict this gargantuan abuse of true religion in the End Times, which seem to have begun around 1800 A.D. – not long ago, in terms of human history, still less the history of the Earth.
        The account of Creation in Genesis is telescoped into 7 days – yet otherwise it is astonishingly accurate in terms of evolutionary biology. The total destruction of all humans save Noah and his family is also accurate in terms of repeated historical events in the Ancient World. The Modern World too has recorded similar wipe-outs of so-called “tribal” peoples, and will record far more one day soon of all peoples – after all, all peoples are tribal in biological terms, however civilized they may think they are..

  5. William Rees gets better and better, and we can only hope he lives to be as old as Methuselah (969, allegedly), who was the son of Enoch, and the grandfather of Noah. Humanity nearly died out from its excesses in Noah’e time (in the Near East at least), but it got a reprieve then and has had several since then. When we look at species collapse in other species, we often see a Remnant rather than complete Extinction, and the same has been true of many great human civilizations before our global one. A Remnant often survived – for instance the Amerindians, but there are many other examples in other continents.
    It is hard to avoid the conclusion, that humans regualrly need to be reduced to a Remnant IN ORDER TO survive. If this sounds simpliistic, it is none the worse for that, IMO. Nothing wrong with Remants, according to the Old Testament – au contraire.

      1. Wow – I am laughing but thanks for mentioning some really Dark Greens – Aldo Leopold and Garrett Hardin. When I was a teenager Ecologists were really Dark – Arne Naess for instance. Later versions are watered down and appear not to have heard of the pioneers, who have been deliberately thrown into Room 101 it seems. It is both sad and funny to see modern watered down versions of, say, Rudolf Bahro and Ivan Illich, being treated (and mistreated) as “controversial” and even “seditious”. What on earth would polite society make of Leopold et al? They would have to get out the smelling salts, like Victorian ladies having a fit of the vapours.
        I see David Ehrenfeld is still alive, though his Ecologist wife sadly died in 2011 (of leukemia). However, either Ehrenfeld is not a fan of youtube or youtube is not a fan of Ehrenfeld, so he is far from a household name even amongst environmentalists. The wiki entry on him is fine, and has a neat summary at the end which amused me as it is a perfect snapshot of general reactions to really Dark Greens.
        “Ehrenfeld is widely regarded as one of the most prominent conservation biologists in the world. With more than forty years of teaching experience under his belt at Rutgers, he has come into contact with hundreds of students and colleagues. As a result, Ehrenfeld is warmly received throughout campus for his rapport with students and faculty.
        Many of his critics, such as sociologist Robert Bierstedt, argue that his literature contains a pessimistic connotation and that he speaks through sermons in his writings. These critics claim that Ehrenfeld’s literature presents a bleak future and tends to focus more on the negative aspects of society towards the environment. Yet, others insist that his work represents optimistic viewpoints in that it depicts the capacity of humans to reverse the forewarned implications of humans’ environmental actions.”
        I should add that Ehrenfeld is not shy about praising Hebrew scripture and commentary for its stern stance on the natural world and man’s place in it – this has probably ruffled a few feathers too, but he will not budge thank goodness.

  6. “And Leopold went down to the land of his fathers. And Leopold begat Hardin, who begat Rees, who begat …” Well, I certainly cannot name any worthy successors but that does not mean there are none in the pipeline …. and I mean in the pipeline, because when things get really really bad, it is often a defector from the heart of darkness who has the insider knowledge and the righteous fury (saeva indignatio) to mention the unmentionable. Certainly we could do with a refugee from the nuclear power industry to rear up and deliver a KO to “greens” saying nuclear will save us.
    Not that a Hardin for the 21st century will have any more effect on the course of events than Hardin himself did. But such people provide an honourable record for later centuries, should any records survive – or anyone survive to read them. Any successor would provoke similar outrage in their contemporaries, the level of outrage merely serving to measure the strength of their arguments – and for this reason Pentti Linkola, the Finnish “ecofascist” might have been a candidate but sadly he died in 2020. He was adamant that humanity must from now on be cruel to be kind, or else even more cruelty would descend upon us willy nilly. He had zero interest in human rights, needless to say.
    In some ways, Linkola explains why there probably can’t be a successor to Leopold, Hardin, and Rees. Humans can be cruel – but not cruel enough to avert national Overshoot, still les global Overshoot. Only the Four Horsemen of the Acropolis as we used to call them at school, can do the necessary. They are not supposed to arrive until the end of this world, but they have pitched up quite a few times already in the long history of mankind, and the next time probably won’t be the last one either.

  7. Countries Who Are Unable To Produce Their Own Food
    Rank Countries Without Sufficient Food Supply
    1 Afghanistan
    2 Burkina Faso
    3 Burundi
    4 Cameroon
    5 Central African Republic
    6 Chad
    7 Democratic Republic of the Congo
    8 Djibouti
    9 Eritrea
    10 Ethiopia
    11 Guinea
    12 Iraq
    13 Kenya
    14 Lesotho
    15 Liberia
    16 Madagascar
    17 Malawi
    18 Mali
    19 Mauritania
    20 Mozambique
    21 Myanmar
    22 Nepal
    23 Niger
    24 North Korea
    25 Republic of the Congo
    26 Sierra Leone
    27 Somalia
    28 South Sudan
    29 Sudan
    30 Swaziland
    31 Syria
    32 Uganda
    33 Yemen
    34 Zimbabwe

    1. In a previous posting a link to a video from an Iranian women was given. The link showed how England did not produce enough food to feed it’s population and a lot of food (for much of Europe) was grown in parts of Africa. A recent story in the latest Smithsonian Magazine was about how the Choctaw tribe sent food aid to help the Irish during the potato blight. The farmers grew grain for export and potatoes for consumption. The British government would not allow the farmers to consume the grains thew grew as it might create a financial problem for the landlords. Seems little has changed. Perhaps a good list would be to include those countries that could not grow enough food for their own citizens.

      Although I found the article great I thought it would bee too deep and scientific for most. Perhaps another version in a more vernacular version would be warranted.

  8. Thank you, Bill Rees, for your steady stream of Wake Up calls over the past 35 years.

    And thanks to all at TOP for inviting him into our mind-home.

  9. A very important read. Thank you. It seems to method the most humane actions of industrial civilization, the development of vaccines and antibiotics and other medical treatments that saved lives, especially he lives of infants and children, are what caused the vast increases in human population growth. Before this, growth rates were fairly low. My own research among African hunter-gatherers, in the Kalahari, and with horticulturalists and pastoralists in the Sahel, indicated a population growth rate that was very low in earlier generations – due to hight infant and childhood mortality. It was between 0.04 and 0.06% per year.

    This was similar to other estimates:
    “…suggests a trajectory of continuous, long-term Wyoming-Colorado hunter–gatherer population growth of 0.041% from 13,000–6,000 cal BP, doubling roughly every 1,700 y, within which there were short-term fluctuations during which growth rates were sometimes more than an order of magnitude larger (i.e., r > 0.4%), doubling in less than 200 y. Spanning the transition from a highly mobile, large-game–focused Paleoindian adaptation to a less mobile Archaic adaptation that made greater use of small game and plants (5), the long-term Wyoming-Colorado rate is broadly consistent with radiocarbon estimates for North America overall [i.e., including both hunter–gatherers and agriculturalists and bridging from one to the other (6)], almost exclusively hunter–gatherers in Australia (7), European agriculturalists (8), and prehistoric population worldwide (9). That the rates of population growth indicated by these studies are so consistent with each other has important theoretical implications.”


    So humanity did not have growth rates, prior to the invention of these medical innovations, that was very much above stability: although one can calculate the doubling time based on these rates, and that doubling time is sufficient to account for the spread of modern humans to all known terrestrial ecosystems. However the sudden increase in rates of population growth is, as you say, largely due to the industrial civilization, and the innovations that caused it are by no means without remedy in future. Independent access, for women, to birth control, as well as greater economic equality and access to education and employment, seem to me to be the most important measures.

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