The End of Growth:

The Beginning of Contraction

George Mobus

For Global Population Speak Out

Population Overshoot

Premise: There is a natural limit to the size of a population that can be sustainably supported by its environment and should a population grow beyond this limit natural negative feedback mechanisms will act to reduce the population back to numbers within that limit; often pushing the population much lower than the original limit due to over consumption of the resources that take more time to recover.

This premise has been observed to be correct for virtually every biological species tested (by science or by nature). It has even been inferred to be true for Homo sapiens (see "Collapse" by Jared Diamond, esp. Chapter 2 on Easter Island) in semi-closed environments. Yet today this is still largely ignored by economists and politicians as well as some religious leaders who take the position that for man things are different. According to their beliefs we humans have transcended mere biology and so are somehow exempt from the laws of biological systems. They believe infinite growth is not only feasible, but desirable. Moreover, not just the growth of the population, but the increase in the amount of natural resources any given individual consumes is a sign of economic and societal good health.

But the evidence that unfettered growth is not only not feasible, it is destructive to both mind and body of humans has begun to accumulate. It is clearly destructive to the natural world as well. Human population size and per capita consumption do not scale well beyond a certain point. That point is captured by the concept of carrying capacity. This is the environment's capacity to provide all of the resources needed by a species as well as the ability to dissipate that species waste products. Application of carrying capacity concepts to the human species has been tackled by a number of researchers (see this reference for some background). The outcomes from these efforts are theoretical estimates of the optimum population size for the planet, given assumptions about the level of consumption per capita (see I=PAT explanation). While the range of estimates is from as low as five hundred million to four billion, there seems to be a growing convergence pointing to a number closer to between one and two billion. At this number, say one and a half billion, it is estimated that the population is sustainable at a reasonable living standard. But there are some hidden assumptions in this figure. Chief among these is that we have developed an energy infrastructure that provides high quality energy from renewable sources and is carbon-free. Further, the waste products from our industry cannot overwhelm the environment's natural ability to dissipate it.

Clearly there is a substantial difference between the 9+ billion projected for the year 2050 by the UN Commission on Population and Development and an "optimal" population of approximately one and a half billion at steady state. The central question is: How do we achieve a number in line with the long-term sustainable carrying capacity of the planet while preventing a population crash as has been seen in other biological systems?

Kenneth Smail, Emeritus Professor of Anthropology at Kenyon College, has written extensively on this topic. See, for example, his article, "Confronting the inevitable: Population reduction, voluntary and otherwise" at Culture Change. Professor Smail, in past writings, has projected a population reduction rate predicated on having a reasonable amount of time to carry it out through, "...a well conceived, clearly articulated, flexibly designed, broadly equitable, and internationally coordinated program..." (from the above linked article). Ideally, once we as an intelligent species recognized the problem, we would set about reducing our numbers in an essentially humane program in which global fertility rates are significantly reduced (perhaps to somewhere around 1.50 to 1.75) and subsequent population reduction would take place by natural attrition. Even under these ideal conditions, however, it might take as much as 200 years (or more) to accomplish a reduction of the this magnitude. Unfortunately, as Professor Smail also recognizes, there are two rapidly emerging developments that may well make this orderly transition to sustainability impossible, and humanity had better (and as quickly as possible) become fully cognizant of the existential issues involved. .

One of these conditions will unroll over a somewhat longer time scale, at least as currently believed. Its ultimate impact, however may be such as to reduce the carrying capacity of the planet much further than anticipated by the kinds of analysis referred to above. That is the climate change impacts due to global warming induced by anthropogenic greenhouse gasses. The reason this problem exists in the first place is owing to the growth of the population and the increasing consumption rates of developed world populations. So in a long-time scale negative feedback loop our population size will be impacted by its current size. This essay will not dwell on the impacts of climate change. I note only that such changes as are currently anticipated will require a tremendous amount of work to adapt civilization for survival. As we will see this ability is compromised. In concert with climate change there are other probable stresses deriving from conditions like pollution of the ocean, availability of water, dependence on optimal food and power distribution that will be subject to disruptions, possibly leading to social suffering and conflict. Climate change is expected to aggravate all of these conditions, which would become accute even without the added stress of climate disruptions.

The other limiting factor that is just now coming to light, and that will likely have a much sooner impact on our thinking, is the peaking of high quality energy production that will leave industrial civilization without a basis. The first shock in this phenomenon will be the peak of oil production.


Energy is the ultimate limiting factor in our world. Energy is the capacity to do work. This includes mechanical, electrothermal, and electrochemical work. The first is represented by transportation, the second by incandescent lighting, and the third by both chemical processes and our own physiology. We get our personal energy from food. But we also need to live in appropriate thermal conditions, so our houses and clothing help protect our loss of energy through chilling. There is absolutely nothing in our world that happens without the use of energy doing some form of work. And that especially applies to our economy. In fact, the economy could be described completely in terms of energy flows, irrespective of monetary considerations. This latter fact often baffles people who are so used to thinking about the economy in monetary terms. Yet it is pretty easy to demonstrate. Take away all forms of money and people will revert to barter for the things they need (history provides several examples where money became absolutely worthless due to hyperinflation, effectively removing money from the economy!) Take energy (including food) away from the economy and see what gets done.

Given enough energy one can rearrange various kinds of atoms into the configuration of an airplane and with stored energy on-board, fly through the sky. Given enough energy one can pump clean(ish) drinking water from the Arctic to anywhere in the world. Given enough energy we could do almost anything within the laws of nature. Indeed, the whole concept of substitutability, proffered by economists as the solution to high prices, is a possibility only because we can apply extra energy to do the work needed to obtain and rework different resources. When the energy we need is so easy to obtain, we appear to have no limits.

Unfortunately we are running out of energy (see below). Or rather, we are running out of the energy that is immediately available to do the work of our economy. I have blogged on several occasions in the past on the energy predicament we face. Starting last January 30th I started blogging about possible solutions to the energy problem, Steps toward an energy solution, "Waking Up". This was followed by the second step, on Feb. 2nd, Steps toward an energy solution 2, "Follow the science". There are more steps to be covered in the future, but on Feb. 2nd I took a slight excursion with "Our energy cocoon" to explain the per capita usage of energy in the western world, particularly the USA. And then followed on Feb. 7th with the third step, Steps to an energy solution 3, "Eliminating Unnecessary Consumption". In this last I provided a conceptual model of the problem facing humanity.

In each of these I have alluded to the fact that any program that purports to solve the energy problem is compromised by one simple fact. There are too many people on the planet to allow any reasonable approach to work. No matter how much energy per capita we, in the developed world, reduce our consumption by, there are more people needing energy. Below I argue from the standpoint of equity, social justice, and development, why the fact that there will be less and less energy available in the future will not help mankind achieve our Millennium Development Goals. Shipping food to hungry people, building schools and training teachers, providing clean drinking water, and all of these require energy to implement.

Oil is the king pin in our energy infrastructure. Without oil our industrial capacity grinds to a halt. Even the mining of coal and transporting natural gas is dependent on oil. In theory natural gas could replace oil in transportation, but its supplies are more limited than those of oil. The problem is that oil has been an ideal form of fuel as well as a major input to petrochemicals and plastics, without which our modern lifestyle would be impossible. And we are reaching the limits of how much oil we can produce (see this tutorial by Gail Tverberg, aka Gail the Actuary, at the OilDrum.) Indeed there is considerable and growing evidence that we have passed the global peak of production (watch this video by Matt Simmons and this interview with T. Boone Pickens).

The peak may actually be a plateau for another decade or longer. What is currently complicating the picture on oil production is the destruction in demand caused by the global recession now growing deeper. Ironically, the runnup of oil price last summer was, initially, in response to the outstripping of supply by demand (growth in demand having been driven largely by China and other more rapidly developing economies) but apparently greatly aggravated by investors rushing to put their cash into the next bubble, in this case oil futures. More ironically still was the way this impacted the cost of energy in general, mostly transportation fuels prices. This put a huge hit on the US economy and may have been instrumental in triggering the housing finance collapse, set up by the already troubled housing price bubble. That, in turn, brought down the derived financial markets and the collapse of the whole economy. Simply put, the oil price spike poked a hole in the hyperinflated bubbles of housing, finance, and stocks. The subsequent deflation has been breath taking. With the collapse of financial markets, particularly credit for housing and consumption, the whole economy has been brought to its knees, and the worst is probably yet to come.

Now the giant feedback loop has had a deflationary affect on oil prices, which themselves collapsed along with demand. But, there is still one more irony. This price collapse has led to cancellation of many new oil production projects, thus diminishing supplies as the older oil fields continue to reduce their outputs. Many experts expect to see something like a wild oscillation in oil production, demand, and prices over the next several decades as this feedback loop continues to obscure the real story on feasible oil production. Just watching oil prices will not tell us what is going on under the hood, in actual oil production itself.

Nevertheless, the trend is clear. Oil production has nowhere to go but downward. This would be bad enough but there is yet another factor that is going to make the problem far more aggravated than that. Indeed, this additional factor plays subtly into the peaking phenomenon itself. That phenomenon is the declining energy return on energy invested, or EROEI (also EROI by some authors). See my blog Steps toward an energy solution 2, mentioned above, for more information. The simple fact is that not all oil (or any energy) is created (actually 'converted'; energy is neither created or destroyed!) equal, nor, indeed, is it equal to all other forms of oil (or energy). Put simply it takes far more energy to extract oil from below the ocean floor than from a ground-based well, say in Saudi Arabia. That energy, in oil equivalents, needs to be subtracted from the energy extracted in order to determine the net energy which is available to do other economic work. EROEI is a form of efficiency ratio, but it tells us how much net energy we can expect to pump into the economy, hence how much work we can expect to do. That ratio has been in decline (for oil) and that decline has accelerated during the past thirty years or so (see this post by David Murphy at the OilDrum). My model, given in "Steps toward an energy solution 3", reproduced below, shows the effect of the combination of peak oil and declining EROEI. The rate of decline in net energy is dramatic and has all the earmarks of catastrophe.

At the same time it is becoming clear that the total energy production to be expected from so-called renewable sources cannot begin to ramp up to the predicted needs in time to replace energy from fossil fuels. Among other factors affecting the rate of build-up of alternative energy capital is the fact that it currently takes fossil fuels to manufacture, deliver, and install the alternative equipment. Thus, as net energy from fossil fuels declines, the logistics of switching to alternative and truly renewable sources is problematic (it is further complicated by neoclassical economics arguments involving the inability of alternative sources to compete with fossil fuels — the irony here is that if fossil fuel prices go back up then the cost of delivering alternative equipment will go up as well!) Our energy situation is a classical double-bind, or Catch 22. Moreover in our exhuberance over the seeming abundance of cheap energy for the last thirty or forty years we have spent an increasing portion of that energy inheritance on frivolity and hedonic satisfactions while ignoring the fact that we were burning a finite resource.

Over the past two centuries, two critical developments have been greatly enhanced by the burning of fossil fuels. The first is the increased capacity to convert natural resources into economic wealth (and here I am allowing calling SUVs wealth, though reluctantly so). The second was the conversion of fossil fuels into human biomass. We've seen the results of these two conditions in the form of ever more people and many of them in the developed world carrying ever more individual mass. What happens if you take the fossil fuels away?


The population is going to grow even larger than the 6.7 billion we are now passing. According to the UN report "World Population Prospects" global population should continue rising but with lower fertility rates until there are roughly 9.2 billion people in 2050. Their approach did not include the notion that energy resources are going to be declining over the next several decades, so this number may be optimistic. It takes considerable energy inputs from high grade sources to maintain an economic system capable of feeding people. Energy, rather than land, will be the main limiting factor in feeding large populations. By 2050 our net energy available may be as low as three quarters of what we have globally today, some say much lower. No combination of renewable energy, nuclear, efficiency improvements, and conservation will suffice to simply replace what will be lost from fossil fuels. Part of the problem is that fossil fuels are needed to power the construction of alternative energy conversion equipment, the power grid, and other capital improvements in energy efficiency and conservation. bootstrapping wind turbine construction and installation from wind turbine power is not terribly feasible and would, in any case, take far longer to implement.

There is no escaping the fundamental facts of physics and biology. The size of the population and the level of wealth per capita depend completely on the flow of high grade energy. Furthermore there is no escaping the laws of ecology either. The more energy and physical resources people use up, the less is available to sustain the Ecos. Ultimately human life depends on the ecological services that the Ecos provides. These are incontrovertible and inconvenient truths. We humans do not have a choice any more. Two hundred years ago and further back in history it might have seemed as if we were capable of anything we desired. Throughout the entire history of humanity our energy resources were expanding. We found one better source of energy after another. We invented technologies to take advantage of these energies and make our lives more comfortable and safe. Inventions led to access to even more energy. There truly seemed no limit. So it is easy to understand our current conundrum. Short of a technological miracle, a completely new source of energy, which would only really put the problem off for a few more years, we are now faced with something completely new. And it is understandable that some continue to rail against (most probably ignore) the reality — the downstream consequences are almost unthinkable.

In spite of some proportion of humanity benefiting from increasing availability of energy a larger portion of our kind have never realized the wonders of the developed world. The more energy we obtained, the more wealth we created from it, the larger the number of the world's poor grew. Even as the relative percentage of people entering into the developed state enjoyed by the modern industrial/technological civilization the total numbers of the poor have grown. In part this can be explained by the only real 'trickle-down' theory that works. The poor have scavenged from the meager scraps and refuse from the rich. The energy excesses of the developed world have trickled into the under developed economies but at just a subsistence level.

Now, in our age of electronic communications, suddenly, people of good heart in the developed world are realizing the plight of the world's poor. And just as the energy flow peaks, we are moved to want to help those in the undeveloped world reach the levels of wealth we have taken for granted. It is certainly a worthy sentiment. Unfortunately we have no idea where the wealth will come from. With less and less energy we will produce less and less wealth. But there are going to be ever more people wanting wealth.

Our choices, as a sentient race of beings, are rapidly narrowing. The two major options resolve down to this: either we choose to take actions to both reduce the numbers and reduce the consumption of energy in some equitable fashion, or natural forces will drive our numbers down while making everyone who survives much poorer.

As I have been describing in my series on sapience (the brain/mind basis of wisdom), making so-called rational decisions depends on guidance from two other areas of the mind, beyond intelligence and creativity. One of those areas is biologically ancient and largely hardwired, the affect or limbic system. It biases our perceptions and decisions with emotional content. When this works as it is supposed to, it helps us pare down our decision choices to those that we 'feel' comfortable with by avoiding those that have negative connotations. Somewhat counter intuitively this actually makes what we call rational decision making feasible. It keeps our brains from analysis paralysis. The other, more recent evolutionarily and dependent on our ability to learn, is the sapience system. It uses tacit knowledge gained over a lifetime to add judgment to the rational decision-making process. This is humanity's claim to biological superiority in the evolutionary sense. It has made humans successful in the competition for resources. Unfortunately, the evidence suggests that higher judgment is not yet up to the task of moderating cleverness and emotions in their drive to short-term optimization. We're not sapient enough to direct our own cleverness in making wise choices. Indeed, I have argued, it wouldn't be necessary to write an essay like this if we were sufficiently wise to have avoided our current predicament. The problem wouldn't exist.

But that is just wishful thinking; "...if only things had turned out differently". Evolution produced what it produced. Us, as we are. The single most important question that we have to grapple with is this: Will we have enough wisdom to take actions that will make it possible for humanity to continue to evolve? It gives no pleasure to suggest that the potential for species extinction lies in this impending crises. But it does.

What happens in the next ten to twenty years in terms of facing and discussing the problems of population and consumption will, I think, decide the fate of our species. Ignoring the reality of energy flow diminishment and its consequences will not make it go away. Even if tomorrow we were to find a huge, close to the surface, field of oil to exploit it would only postpone facing the problem a bit longer. The problem is fundamental.

So, humanity, what will we choose? Will we, as a sentient species, choose voluntary and concerted action to minimize suffering, or willful ignorance? Will we choose sacrifice and hard work or the likelihood of unspeakable horrors? The time to choose is now.


Technological cornucopianism: The belief that technology will save humanity from reaching limits.

Logically, the argument goes: We have always found a technological solution before (e.g. Green Revolution) so we will find one this time. This is, however, fallacious. Substitute "I've never gotten cancer before, therefore I will never get it!" to see the fallacy. Having faith in technological solutions in the area of energy shows a profound lack of understanding of energy. Everything we know about technological advancement has been based on taking the availability of energy for granted. We could always build a bigger, faster version of a machine simply because energy has never been a limiting factor before. We can't apply that same reasoning to the conversion of renewable energy sources to usable forms. First, the Second Law of Thermodynamics will always rule; the more energy you convert the more heat you produce — scale matters. Second, those sources are generally very diffuse, not well distribute relative to where the work is needed, and intermittent. They require concentration, storage, and transportation that will, themselves, have an ultimate energy cost. We must, of course, plan a course that exploits all feasible renewable sources of energy as best we can. But we had better not believe that those sources will provide equitable living standards for the kinds of population sizes currently projected. First determine how much energy will be practically available. Then determine what sort of living standard is comfortable for the average person and how much energy it takes to support that energy cocoon. Then you will know how many people can be supported in a steady-state, sustainable world.


I am very grateful to following people for providing kind reviews and insightful comments. Professor Ken Smail, who has been an early and prolific writer on the need for population reduction, provided helpful suggestions, all of which have contributed to the clarity of the essay. Professor Wayne Hamilton, who has made many insightful contributions to this blog, also has helped me focus more tightly on key ideas. Several other reviewers provided useful feedback, but wish to remain anonymous. Nevertheless, I want to thank them; they know who they are!