You are here

SPA: Ending population growth a critical climate-change mitigation tool

Ending world population growth as soon as possible is critical if the world is to limit global warming to 2oC, according to Sustainable Population Australia (SPA).

Working Group III of the Intergovernmental Panel on Climate Change (IPCC), in its report issued yesterday said ‘urgent action’ is needed if we are to keep within the internationally agreed limit of 2oC.

According to Dutch economist Reyer Gerlagh, co-ordinating lead author of one of the report's chapters, growth in emissions is currently tied to economic and population growth. It would take ‘a drastic change to the system’ to break this connection.

SPA National President, Ms Jenny Goldie, says if growth in greenhouse gas emissions is tied to ‘economic and population growth’, then it follows that ending population growth is essential if the world is to limit warming to 2oC.

The UN’s middle projection for 2050 is 9.6 billion, a third more than the current population of 7.2 billion.

“If we go to 9.6 billion, we would emit a third more greenhouse gases by mid-century from population growth alone,” says Ms Goldie. “Yet significant reductions in emissions are needed by then.

“Population stabilisation and even reduction has to be an essential part of the mitigation mix. Moving to a low carbon economy is, of course, necessary with fossil fuels phased out as quickly as possible. If, however, population continues to grow inexorably, then any success in emission reduction through adopting low carbon technologies is likely to be offset by population growth.”

Ms Goldie noted that the IPCC media release had said: ‘Land is another key component for the 2°C goal. Slowing deforestation and planting forests have stopped or even reversed the increase in emissions from land use.’

“Yet while ever there are more mouths to feed, more forests will be cut down to grow food. There is no way growth in yields on current farmland will provide for the growing population, especially in light of climate change. More people mean fewer forests,” Ms Goldie says.


Our deafening silence about what is happening and why it is happening with regard to the unbridled growth of the human population on our watch serves to give consent to preternatural pseudoscience of economists and demographers that is broadcast in the mainstream media without objection. By not speaking truth to the powerful, according to the best available science and ‘lights’ we possess, we become accomplices to their ubiquitous abuses.

Extant scientific research regarding the population dynamics of Homo sapiens has to be openly acknowledged, objectively examined and honestly reported. Population scientists and ecologists have been shown to be as vulnerable to denial of apparently unforeseen and unfortunately unwelcome scientific evidence as well as to capitulation to the entreaties of all who choose favorable unscientific research to be spread by the mass media without meaningful objection from many too many members of the scientific community. It is a deliberate breach of responsibility to science and humanity for population scientists and ecologists not to object to the spreading of false knowledge and thereby, to fail in the performance of the fundamental duty of disclosing what could somehow be real and true about Homo sapiens and the workings of the existential world we inhabit, according to the best available scientific research.

Let us recognize the willful denial of the ecological science of human population dynamics. Where are the population scientists and ecologists who are ready, willing and able to attest to or refute empirical evidence that human population dynamics is essentially similar to, not different from, the population dynamics of other species; that human population numbers appear as a function of food supply; that more food for human consumption equals more people, less available food to consume equals less people and no food equals no people? No exceptions! Are these scientists blind, deaf and electively mute in the face of new scientific knowledge. Most reprehensibly, their refusal to accept responsibilities and perform duties as scientists has made it possible for pseudoscientists to fill the mainstream media with false knowledge about the way the world we inhabit works as well as about the placement of the human species within the natural order of living things.

Is it not science, and science alone, that most accurately allows us to confirm our perceptions as objective correlates of reality and truth? Without science, thought leaders and power brokers in cultures everywhere are free to widely transmit attractive ideas at will, regardless of the extent to which the ideas bear a meaningful relationship to what could be real and true. For example, a preternatural factoid like “food must be produced in order to meet the needs of a growing population” is deceitfully given credence as a scientific idea although it reflects the opposite of the actual relationship between food supply and human numbers. Findings from science indicate population numbers are the dependent variable and food the independent variable, just like the population dynamics of other species. By increasing the food supply, we are in fact growing the human population, are we not?

The idea that human exceptionalism applies to the population dynamics of Homo sapiens, that human population dynamics is different from (not essentially similar to) the population dynamics of other species, is a pseudoscientific factoid, bereft of an adequate foundation in science. Overwhelming scientific research regarding the human population indicates that human population numbers appear as a function of food supply. For many this scientific idea is on the one hand irrefutable and on the other hand unbelievable. So completely are many too many professionals enthralled by the notion of human exceptionalism. Exploding human numbers in the past 200 years are the natural result of the dramatically increasing production and distribution capabilities of food for human consumption that occurred with the onset of the Industrial Revolution and later on during the Green Revolution.

Please consider that demographers and economists are not scientists. They are presenting false knowledge that is appealing because it presents what all of us wish to believe about the way the world in which we live works as well as about the exceptional nature of the human species. Human beings are mistakenly believed to be outside (not within) the natural order of living things. The false knowledge regarding human species’ exceptionalism with regard to its population dynamics is determined de facto by whatsoever is politically convenient, economically expedient, socially desirable, religiously acceptable and culturally syntonic. Such de facto determinations of what is real about human nature and the existential world are based primarily upon ideology, not science.

Refuse to be duped by clever, absurdly enriched vendors of words and highly educated sycophants. These ‘talking heads’ duplicitously claim they are scientists and then promulgate preternatural ideas and pseudoscientific theories that are passed off as well-established results of scientific research without objection from scientists.

Let us examine the false knowledge from conventional, Neoclassical Cornucopian Economics and the Demographic Transition Theory. These theoretical perspectives are not connected to the foundation of science. The speciousness of what is presented by demographers and economists and then broadcast ubiquitously by the mainstream media is in need of correction by scientists. Ideas of endless resources availability in a finite world and an indestructible ecology that is in fact frangible are fabricated. Automatic population stabilization; a benign end to population growth soon; a glorious world by 2050 when the entire human community will reap the benefits you and I enjoy now because everyone in the human community will have entered the fourth and last stage of the demographic transition, all of these notions are fanciful and ideologically-driven. Such false knowledge as we find in the pseudoscientific disciplines of economics and demography needs to be eschewed. The best available scientific evidence must to be our guide because science stands alone as the best method by far for apprehending what could be real and true. Science needs to be categorically distinguished from all that is not science. Then, perhaps, we will be able to see more clearly how the existential world we inhabit actually works and more accurately perceive the placement of Homo sapiens within the natural order of all living things.

The imprimatur of science has been not so surreptitiously usurped by pseudoscientific disciplines in which professional research is primarily underwritten by wealthy power brokers and corporations. Economic and demographic research is designed and the findings presented so as to comport with the transparent self interests of the rich and powerful. Where are the scientists who will speak out to correct such widespread misunderstanding and reckless wrongdoing? The conscious silence of scientists serves to give consent to ubiquitous unethical professional behavior that cannot be tolerated any longer because of the confusion it engenders among those in the human community who are rightly seeking an intellectually honest understanding of the global predicament we face and a path to a sustainable future that can only be derived from the best available scientific research. The disciplines of demography and economics are prime examples of what science is not. Perhaps the findings of demographic and economics research will soon be widely recognized and consensually validated as preternatural pseudoscience.

“Speak out as if you were a million voices. It is silence that kills the world.” — St. Catherine of Siena, 1347-1380


Thanks for your contribution. It gives me the opportunity to tell you about my work, which answers some of your questions and raises others. With regard to humans and other species, I have developed a theory that there are a range of genetic algorithms that are mediated via hormones in response to environmental information (about food, water, climate, space and spatial distance from parents, siblings and cousins). You can read about it in Sheila Newman, Demography, Territory, Law: The Rules of Animal and Human Populations, Countershock Press, 2013 on kindle here: or as paperback here:

I am familiar with your "Expansion of the Classic Demographic Transition Model", which I discuss in my book.

Dr Salmony, you write in your comment to which I am replying, "Where are the population scientists and ecologists who are ready, willing and able to attest to or refute empirical evidence that human population dynamics is essentially similar to, not different from, the population dynamics of other species; that human population numbers appear as a function of food supply; that more food for human consumption equals more people, less available food to consume equals less people and no food equals no people? No exceptions!"

Here is my response:

1. It is true that the imperative to feed the world is abused as a way of upping population and selling more products as well as food. The class that benefits financially from ever increasing population influences governments to engineer populations upwards, via a variety of means. The classes that benefit from population growth commercially consistently promote it and they own the mass media. They also are the class that sponsors research in our increasingly commercialised and constrained universities, rewarding that which benefits them and leaving in the cold, unfinanced and unpromoted, that which does not, so that it sinks like a stone, along with its author's name, although commercially useful parts may be plagiarised.

It is not clear how conscious this population growth promoting class is of the scientific relationship between certain factors and tuning population growth upwards, but the are certainly aware of the commercial relationships. Conversely, biologists, zoologists and physicists don't tend to look at the impact of commercial relationships, so they don't take these into consideration. Political scientists, sociologists, are capable of studying these things, but those disciplines are very responsive to commercial signals themselves, and tend to be politically,commercially and academically aligned with the focused beneficiaries of population growth. Behavioural psychologists are seen as more empirically based than some social scientists, but they concentrate on individual and species responses to environment rather than ecological interactions and patterns, which turns out to be a problem in studying population. Physical scientists have acculturated to look down on political scientists and so they don't read or promote political science exceptions that would help their own work, even where that social science discovers obvious biological, physical patterns which could be tested by physical and biological scientists and mathematicians. E.O. Wilson advocated 'consilience' but it still hasn't happened.

Study of this subject seems to need scientists who are able to look both at political and biological concepts and indicators, who are not aligned with commercial beneficiaries of population growth, and who are able to work independently. Even if such people exist, it is unlikely that their theories will be read, promoted or discussed, of course.

2. It is true that all animals (including humans, of course) respond to availability of food. They also respond to availability of water, space and to climate. Measuring their response to food alone shows that their response normally causes them to regulate their breeding within comfortable limits. Overshoot is comparatively rare: See Pimentel, D., 1968, March. Population Regulation and Genetic Feedback. Science, Vol.159, p. 1434; Hopfenberg, R. and Pimentel, D. (March 2001) "Human Population Numbers as a Function of Food Supply", 1 Duke University, Durham, NC, USA; 2 Cornell University, Ithaca, NY, USA, \l "_edn110"; and Iwamoto (1978) cited by Hopfenberg and Pimentel, 2001. Op. cit. p.4.

They do not, except under certain current circumstances, breed up to the limit just because there is food there. They usually stay under the food limit.

This fact, of which I feel certain you are actually aware, contradicts your statement that "more food for human consumption equals more people, less available food to consume equals less people and no food equals no people? No exceptions" (...). [2]

In view of the empirical research, I think that your statement needs to be posited more complexely, vis:

"No food equals no people;
More or less food, as long as it is enough to sustain life and reproduction, equals a variety of population number outcomes."

Please note as a scientist who is ready, willing and able to attest to or refute empirical evidence regarding this statement that you make that I have examined your and Dr Hopfenberg's, 'Expansion of the Classic Demographic Transition Model' (2011), respectfully in my book, Demography, Territory, Law: The Rules of Animal and Human populations. I find that a number of additional factors could be considered towards this model, such as the impact of in and out migration, transport changes, and variations between populations. I also find some exceptions to it, to which you may care to respond at some time. [2]

Some questions:

But, in relation to your statements about food dictating population numbers, why do we have some countries where people 'breed up' although they get very little food and suffer long-term malnutrition (Africa, Brazil, Ethiopia, Britain during the Industrial Revolution), other countries where people breed at a lesser rate but overeat to obesity (Australia, United States, Canada), other countries where people eat well and breed up (Saudi Arabia), and other countries where people don't overeat much and don't breed up and had comparatively low birth rates even before the age of petroleum and modern contraception? (France, Japanese Pacific islands). Note that there are big variations between regions and classes of people within those examples.

What about the immigration factors in these different countries? (Immigration can mean everything from rural to city, interregional movement, intersuburban movement, planned invited foreign migration, through to presence of troops and invasion, colonial occupation etc.)

What about different rates of 'marriage' (i.e. potentially productive unions) and how these different rates come about? Malthus was aware of the importance of this factor and documented many variations.

All these factors vary and produce different norms.

The global tendency is towards overpopulation, unquestionably, but not all components of the globe are overpopulating. If we are to solve this problem of global overpopulation, should we not be looking at the peoples and countries that, despite the presence of abundant food, are able to live comfortably within their means (and which [preferably] do not succumb to obesity?)

I have looked at these questions in Demography, Territory, Law, Rules of Animal and Human Populations and find that there are some other factors that have created the situation we are in, which is one with far more available fertility opportunities than available in nature. High fertility is rewarded in some economic systems, such as those where there are no rules against child labour and parents have no way except via wages to increase a miserable family income.

Modern transport gives the ability to travel far and wide and is a significant factor in creating more fertility opportunities because it brings people in touch who otherwise, in small societies, might never have found mates due to kinship prohibitions. Incentives or necessities to move away from one's local birth place (generally due to commercial or military displacement in the forms of planning impositions, economic changes forcing sales of traditional land) lead to people travelling away from their home regions, towards cities and mulitiple fertility opportunities. A classic example of this is late 19th C and 20th century Ethiopia, where land 'reforms' and 'modernisation' with Mennelik II's embrace of 'development' more or less forced people who for centuries had been settled, with highly circumscribed fertility opportunities, to migrate to the cities. Ethiopia went from 4m people in the 19th century, to 80m in the 20th century.

Very importantly, signals about local environment are obscured by global information about food and resources and, more abstractly, economic outlook. (See Virginia Abernethy's, "Not tonight Sweetheart - No Energy.")

Whether the people of a certain region tend to stay at home in clans and tribes or move away and be exposed to new fertility opportunities rarely, often or usually, is partly dependent on what political system they live in. In a political system that does not tend to uproot people and dispossess them, where people tend to remain linked to family and clan, fertility rates will be less, e.g. France vs Britain, with Britain for a long time the nation more subject to displacement, dispossession and higher fertility opportunities. (the subject of my soon to be published second book in the series, Demography, Territory, Law: Land Tenure and the Origins of Capitalism in Britain, which looks at the availability of landless labour in the presence of coal and iron, with diminishing wood, and compares the situation in Britain with France's.)


[1] Source: Newman, S.M., Demography, Territory, Law, the Rules of Animal and Human Populations, Countershock Press, 2013, pp. 79-81. In Pimentel, “Population Regulation and Genetic Feedback,” the author identifies a number of rules.  One is that most species are quite rare, relatively or ‘by whatever criterion they are judged’. This rule helps to construct the idea that huge numbers involved in overshoot by a species are probably rare and do not last for long.  Another is that nearly all animals feed off live material. This observation is important because dead material cannot evolve genetically in response to predation. Pimentel describes field observations and laboratory tests which show that predated populations evolve in response to a particular predator “only if the numbers of the animal are sufficient to exert some selective pressure on the host.”  Using a variety of examples, he observes that the dominant control mechanism operating initially is “competition” (meaning selection), “but genetic feedback became dominant with time and through evolution.”  He observes that “subtle genetic changes” affect the predator, and gives this example:

“For instance, when young pea aphids (Acyrthosiphum pisum) were placed on a common crop variety of alfalfa (Medicago sativa), they produced a mean of 290 offspring in 10 days, whereas the same number of aphids for a similar period on a resistant alfalfa variety produced a mean of only two offspring.  In another example, the mean rate of oviposition (eggs per generation) of the chinch bug (Blissus leucopterus) on a susceptible strain of sorghum (Sorghum vulgare) was about 100, whereas on a resistant strain the mean oviposition was less than one. In both, reproduction in the animals feeding on the resistant plant hosts decreased more than 99 per cent. This reduced reproduction obviously would have dramatic effects on the population dynamics of the feeding animal populations.”

In Hopfenberg and Pimentel, "Human Population Numbers as a Function of Food Supply," (Hopfenberg, R. and Pimentel, D. (March 2001) "Human Population Numbers as a Function of Food Supply", 1 Duke University, Durham, NC, USA; 2 Cornell University, Ithaca, NY, USA >> the authors cite evidence of other species decreasing their fertility by a variety of means which would suggest a hormonal feedback mechanism from food availability in the environment. 

"Some species self-regulate their number to their food resources by maintaining home ranges. Chitty (1995) reported that excess young voles, for example, are forced to leave the home range of their parents... . Possibly more germane is the evidence that a sudden improvement of diet in sheep causes an increased ovulation rate (Schinkel, 1963) and that fasting in mice for relatively short periods of time prior to mating resulted in depression of male libido and reduced conception in females (Christian et al., 1965)."

They attest that this simple relationship between food supply and fertility is also seen in hunter-gatherers who do not have massive infrastructure to complicate their interactions with the environment.

Biologists know that population density itself is a major indication of soil and climate fertility. 
Need to consider a different kind of mechanism 
These studies and observations, however, do not identify a mechanism which would limit fertility in order to avoid indefinitely the experience of restricted calories.  If food shortage were required before fertility dropped then clans and herds would be permanently on the verge of starvation.  That kind of stress would not be conducive to genetic survival. 
"… Iwamoto (1978) has shown that monkey troop size increases rapidly after artificial provisioning, but the level of consumption efficiency of the troop is always maintained lower than the critical point in both the artificial and natural habitat.  Starvation within the troop simply does not occur if the rate of food availability is held relatively constant."
There has to be another mechanism whereby species can adjust collectively to local environmental constraints of their ranges without constantly risking starvation.

[2] My examination is on page 58 of Demography, Territory, Law, op. cit. Your theory coordinates are: Hopfenberg, R., Hopfenberg, E., and Salmony, S., 2011,“The Expansion of the Classic Demographic Transition Model” (Powerpoint file), Global Population Speakout,