Modern techno-industrial society is in a state of dangerous ecological overshoot – too many people are consuming and polluting too much on a finite planet. It is not too late, however, to take a lesson in sustainability from the tiny tropical island society of Tikopia. Hardly anyone has ever heard of Tikopia, but its history should be known by everyone who cares about the future of Earth. Tikopia is the remnant of an extinct volcano in the southwest Pacific Ocean with an area of less than five square kilometres, 80 per cent of which is arable. First settled by people about 900 before the Common Era, the island has been occupied continuously for nearly 3,000 years. Most remarkably, for perhaps two millennia, Tikopians have practised as many as seven forms of birth control and employed other means of harmonizing their lifestyles with local ecosystems. In short, by cultural tradition, Tikopians have managed continuously to maintain their population in the vicinity of 1,200 individuals, or about 300 people per square kilometre of arable land. Even today, islanders explicitly assert that their contraceptive and other regulatory behaviours are practised to prevent the island from becoming overpopulated.¹

Contrast Tikopia with the modern global community. Planet Earth is an island in space with a limited productive land area, but it is threatened by rampant ecological degradation (including accelerating climate change), continuous conflict over habitable territory, incipient energy and food shortages, and growing numbers of political and ecological refugees who can already be counted in the millions. Nonetheless, there are no national or global plans for population management. On the contrary, those few high-income nations whose populations have stabilized or fallen are worried about the expected negative consequences of this trend for economic growth, political influence and social stability; some world religions explicitly consider contraception to be intrinsically evil; and advocates of population policy are often vilified as being neo-Malthusian, antihuman, ecofascist or racist.² In short, the “population question” is still largely a taboo subject in official modern techno-industrial policy circles – and even popular conversation. It should therefore be no surprise that in 2023, Earth’s population of eight billion people is still growing by about one per cent (80 million people) per year.³

Continuous, rapid population growth is a recent phenomenon. For most of our species’ time on Earth, humanity’s natural propensity to expand has been held in check by negative feedback: food and other resource shortages, disease and intergroup conflict. Circumstances changed with the scientific/industrial revolution, and particularly with the increasingly widespread use of fossil fuels, abetted by globalization and trade. Homo sapiens had been around for perhaps 250,000 years before our population topped one billion early in the 19th century, but it took only 200 years for it to balloon to eight billion by early in the 21st century. While improvements in medicine, public sanitation and population health contributed, it was mainly the consumption of coal, oil and gas that made this spectacular expansion possible (half the fossil fuels ever used have been burned since 1990). Fossil fuels are the energetic means by which humans extract, transport and transform the prodigious quantities of material resources needed to support our burgeoning billions.⁴ In short, science and fossil energy enabled H. sapiens to eliminate or reduce historically normal negative feedback and let positive feedback take over. For the first time in human evolutionary history, the scientific and industrial revolutions enabled our species to exhibit its full biological potential for geometric growth on a global scale (figure 1).

The 1,300-fold increase in fossil energy use also drove economic growth. Between 1800 and 2016, Earth experienced a 100-fold increase in real global GDP, representing a 13-fold surge in average per capita income. Material consumption and pollution expanded accordingly. As William Catton wryly observed, the world was being asked to support not only more people, but ecologically larger people.⁵

Beginning with the dawn of agriculture (perhaps the most ecologically damaging of human technologies) 10,000 years ago, humans have gradually become the major geological force changing the face of the Earth. In the past millennium, about 75 per cent of Earth’s land area has been affected by human activity, 50 per cent in just the past 300 years. In the process, up to a third of the world’s forests have been permanently converted, mostly to agriculture, which now appropriates about 30 per cent of the land surface.

The increase in human numbers on a finite planet necessarily competitively displaces wild species. Habitats and food sources appropriated by humans are irreversibly unavailable to other life forms. Thus, the massive conversion of productive ecosystems from their natural state to serve ever more people has had a proportionate effect on the distribution of biomass among land-dwelling vertebrate species. H. sapiens accounts for only 0.01 per cent of Earthly biomass, but the conversion of global ecosystems to support human expansion has eliminated 83 per cent of wild animal and 50 per cent of natural plant biomass. Scientists estimate that Paleolithic humans represented less than 1 per cent of mammalian biomass. However, with the agricultural and more recent industrial revolutions, we now constitute 36 per cent, and our domestic livestock another 60 per cent, of the planet’s (much expanded) mammalian biomass. All wild mammals combined now comprise only 4 per cent of the mammalian total. Nor have birds been spared. Wild populations of many species are in freefall, and domestic poultry now represent 70 per cent of Earth’s remaining avian biomass.⁶

The story is being repeated at sea. Fossil-powered commercial fishing competes directly with marine birds and mammals for food fish. The World Wildlife Fund documents a 68 per cent average decline of monitored birds, amphibians, mammals, fish and reptiles since 1970, which points to a dramatic loss of the health and resilience of ecosystems.⁷ There is little question that the inexorable increase in human numbers and related resource extraction are the cause.

The explosion of the human enterprise is truly an unprecedented phenomenon. Growth rates that modern techno-industrial society has come to accept as the norm actually define the single most anomalous period in human evolutionary history. Unfortunately, Earth has not become any larger. Thus, the immediate consequence of unconstrained population and economic growth is that H. sapiens is well into a state of ecological overshoot. Overshoot means that the human enterprise is consuming even renewable resources faster than ecosystems can regenerate them, and is producing more waste than the ecosphere can assimilate. This is the very definition of biophysical unsustainability.

Overshoot is a meta-problem: climate change, ocean acidification, overfishing, tropical deforestation, plunging biodiversity, soil degradation, falling human sperm counts and pollution of everything are cosymptoms of overshoot. No major cosymptom can be fully addressed in isolation, but all can be solved by eliminating overshoot. Mainstream efforts to slow climate change through the adoption of modern renewable energy technologies, for example, will not solve the climate problem, and can only exacerbate overshoot.⁸

The growing list of so-called “environmental problems” is empirical evidence that we humans are literally depleting and contaminating the biophysical basis of our own existence. We are the problem. Overshoot is ultimately a terminal condition. The acceleration of climate change is merely the most popularized single symptom.

The population factor in overshoot

We can estimate the extent of overshoot using ecofootprint analysis. A population’s ecological footprint is defined as the area of productive ecosystems required, on a continuous basis, to produce the renewable resources that the population consumes and to assimilate its carbon wastes.⁹ In 2017, the human ecological footprint, 20.9 billion global average productive hectares (or global hectares) was at least 73 per cent larger than the available biocapacity of 12.1 billion productive hectares.¹⁰ The excess of demand over supply represents humanity’s ecological deficit and provides a rough estimate of overshoot. Any ecodeficit underscores the fact that the maintenance and growth of the human enterprise is being “financed” not only by the annual production by ecosystems, but also by the pollution of the ecosphere.

The human ecological footprint nearly tripled from about 7.0 billion to 20.9 billion global hectares between 1960 and 2017.¹¹ As can be seen from figure 2, while both per capita incomes (consumption) and increasing populations contribute to material growth, the ballooning human ecological footprint is caused primarily by swelling populations, particularly in middle-income countries.

In high-income nations,¹² wealth-driven growth in material consumption has historically outstripped population growth to produce per capita ecological footprints averaging about 6.0 global hectares in 2016. On average, the wealthy demand almost four times their proportional share (1.6 global hectares per capita) of global biocapacity. The 2016 figure equates to 34 per cent of the total human ecological footprint and a grossly inequitable 57 per cent of global biocapacity. Because of their elevated consumption and outsized ecological footprints, the addition of just 400 million high-income people since 1961 accounts for about 75 per cent of the increase of 3.2 billion global hectares in high-income consumers’ demand on nature.

Turning to upper-middle-income countries, total ecological footprint increased from 2.2 to 8.9 billion global hectares. The additional 1.43 billion people accounted for 4.9 billion global hectares, about 73 per cent of the increase. This increase alone contributed 24 per cent to the total human ecological footprint. In lower-middle-income countries, average ecological footprint expanded by only 40 per cent to 1.4 global hectares, but population increased more than threefold from 0.9 to 2.76 billion. Lower-middle-income demand on nature increased by 2.96 billion global hectares, of which the 1.86 billion increase in population accounted for 2.6 billion (88 per cent). This increase added 13 per cent to the total 2016 human ecofootprint.

Finally, low-income countries saw no increase in their average footprint of 1.0 global hectares between 1961 and 2016, while their populations ballooned almost fourfold from 240 million to 930 million. The population increase of 690 million neutralized any benefits of GDP growth, and accounted for the entire increase in total low-income ecological footprint to 0.93 billion global hectares (still only 4.6 per cent of the global total).

Summing the above estimates shows that, between 1961 and 2016, the addition of about 4.4 billion human consumers contributed about 10.6 billion global hectares to the growing consumption-based human ecofootprint. The total ecological footprint in 1961 was about 7.0 billion global hectares, expanding to 20.2 billion global hectares in 2016, an increase of 13.2 billion global hectares.¹³ Thus, population growth accounted for about 80 per cent of the increase in total human ecological footprint above what would have accrued had populations remained constant while consumption and per capita ecological footprints increased.

Population and sustainability on a finite planet

We can draw several lessons from these data. Most important, while overconsumption and population growth have long been recognized as codrivers of overshoot,¹⁴ population growth is currently the major contributor to total consumption growth and associated negative ecological impacts in all four income categories. Those who object to serious discussion of the relationship between population growth and the human ecocrisis must confront this reality. That said, it is crucial to recognize that ecological footprints per capita differ greatly among income groups – increasing the population of an upper-income country by one average citizen imposes at least the same ecological load on Earth as a six-person increase in a typical low-income country.

This fact serves, first, to underscore the egregious, inexcusable, yet still increasing material inequality between rich and poor people and nations in today’s world. Globalization and unfair terms of trade in world markets enable the citizens of wealthy countries to appropriate legally, by commercial means, several times their equitable share of Earth’s biocapacity from other countries and the global commons. Many wealthy importing countries are running large ecodeficits. Figure 2 shows that available biocapacity per capita is declining in all income quadrants. However, remember that 1.14 billion rich consumers (15 per cent of the human population) lay claim to 57 per cent of global biocapacity, and that forms of ecodegradation not captured by ecofootprint analysis (such as soil depletion, overfishing, noncarbon pollution and ocean acidification) are everywhere disproportionately driven by consumers in the richest nations. Since the human enterprise is in overshoot and is rapidly eroding its own ecological foundations, any effort to achieve sustainability within global carrying capacity must address the fundamental inequities generated by the present world economic order.

Second, these data show that “peak population” and subsequent population decline in high-income countries should be cause for celebration. Population growth in the richest nations generates almost an order of magnitude greater demand for biocapacity than an equivalent numerical gain in low-income countries. Even greater income disparities are revealed by studies of national “material footprints” – the total quantity of raw materials extracted to meet a country’s final consumption demands. The per capita “material footprint” in high-income countries is 26.3 tonnes, more than 13 times the 2.0 tonnes per capita generated by low-income countries.¹⁵ Again, it follows that the most ecologically significant macro-level gains from policies to reduce populations would come from accelerated population decline among high-income consumers.

But this does not mean we can ignore population growth in middle- and low-income countries. There are both socioeconomic and ecological reasons for concerted noncoercive population reduction policies. First, despite the 3.9-fold increase in the total ecological footprint (consumption) in the most impoverished countries, the material well-being of the average person in these countries has remained unchanged. Ballooning populations have negated any gains from increased GDP among ordinary citizens. It follows that the most significant social benefits from stable populations would accrue at the micro level to low-income families in poor countries, who would enjoy larger slices of the economic pie. At the very least, a falling population would empower the poor by giving them more bargaining power in national labour markets.

Second, as was previously emphasized, humanity is in overshoot and running a massive ecological deficit; the world community is financing aggregate population and economic growth by liquidating essential natural capital. Clearly, mere redistribution of income and wealth would not correct this problem.

Nor can eco–deficit financing continue. Like a rocket, the human enterprise can accelerate only to the point that it runs out of fuel, and humanity’s fuel gauge is already in the yellow zone of overfishing, disappearing tropical forests, plunging biodiversity, receding glaciers, falling water tables, degraded soils, incipient energy and resource shortages and more. In particular, there is now less than 0.18 of a hectare per capita of arable land on Earth¹⁶ (which compares poorly with 0.33 of a hectare per capita on Tikopia, a ratio that the island’s stable population has maintained for centuries). Population growth only further drains the global tank and shortens the time until the reckoning. Arable land per capita is declining globally, and the productivity of even our remaining 0.18 of a hectare per capita is dependent on the continued use of dangerously polluting fossil fuel derivatives (pesticides and chemical fertilizers) and on climate-wrecking fossil-powered irrigation, cultivating and harvesting equipment. What is our fallback if we abandon fossil fuels?

In this context, consider the scale of the sustainability challenge. Let’s first assume we could at least stabilize world population, Tikopia-like, in the vicinity of 2023’s eight billion people. Eight billion is already about 73 per cent too high at the global average ecofootprint of 2.75 global hectares (2017 data), and with rising incomes and consumption and the spread of consumer culture, everyone is striving to match the six-global-hectare ecological footprints of today’s average high-income consumers. This is an impossible scenario that would fatally gut the ecosphere. Total demand would exceed 48 billion hectares on a planet with only about 12 billion productive hectares. In short, we would need the biocapacity equivalent of three additional Earth-like planets to supply the demands of just the present population sustainably. As some wag once remarked, “good planets are hard to find.” And, of course, there are no plans to hold the population constant. Demographically at least, we’re headed toward about 10 billion by 2050, and perhaps 11 billion by century’s end.

Alternatively, the present world community might strive to live within global carrying capacity – to work toward achieving “one-planet living.” This would require a reduction in the aggregate human ecofootprint of at least 42 per cent. Assuming we would also choose to capture the benefits of greater equity,¹⁷ we might begin by redistributing the stock of global biocapacity equally among the human population. (For illustration’s sake, we ignore the needs of nonhuman species.) Based on this criterion, each person alive today would be entitled to 1.5 global average hectares (12 billion hectares for eight billion people). This means everyone would have to learn to live off the productive output and waste assimilation capacity of just 1.5 global hectares – and this assumes no further population growth.

Since the consumer lifestyles of residents in high-income countries demand, on average, the productivity of 6.0 global hectares per capita, the world’s wealthy would have to reduce their ecofootprints by about 75 per cent. While the lifestyle changes implied by this requirement seem impossibly extreme and would be strenuously resisted, this estimate is quite conservative. Indeed, as early as 1993, the Business Council for Sustainable Development reported, “Industrialised world reductions in material throughput, energy use, and environmental degradation of over 90 per cent will be required by 2040 to meet the needs of a growing world population fairly within the planet’s ecological means.”¹⁸ Several recent estimates of necessary rich country reductions fall within the same ballpark.¹⁹ (These analyses typically fail to explore the need for population reduction.)

On the positive side, global sustainability with justice would mean that citizens of low-income countries would theoretically be able to increase their consumption by 50 per cent. Their materially improved lifestyles would increase their ecological footprint from one global hectare to the targeted 1.5 global hectares per capita.

This analysis makes clear that without the equity provision and significant population reduction, the world community could achieve sustainability only if its impoverished billions remain poor and the currently wealthy greatly reduce their material consumption. In the real world, of course, the population is still growing and there is zero international interest in sizing the global economy to fit within carrying capacity or to share the world’s bounty more equitably.

Perhaps this is to be expected. Despite our much-vaunted high intelligence, H. sapiens is not primarily a rational species. We tend to be foolishly shortsighted and are prone to selfishness.²⁰ Emotions, instinct, cognitive dysfunction and acquired habits, often operating beneath consciousness, dominate personal and political behaviour.²¹ For example, humans share with all other organisms the inherent propensity to expand to fill all accessible habitats and to use up available resources, but with the major difference that our technological prowess is constantly upgrading the resources that are “accessible” and “available.” (Even Tikopians eliminated much of their island’s original fauna before being forced by their self-created circumstances to control their numbers.) To complicate matters, modern techno-industrial culture’s natural propensity to expand (nature) is being reinforced by a neoliberal econocultural narrative (nurture) centred on continuous material growth propelled by technological innovation. The result is that, in many respects, humanity’s expansion and depletion of Earth are analogous to a bacterium species’ colonization and depletion of nutrient broth in a Petri dish.²²

Can we break the cycle?

Knowing history, must we repeat it? Humanists and other optimists insist that H. sapiens has unique qualities that we have arguably yet to exercise fully in addressing overshoot, among them the capacity to reason logically from the evidence and the ability to plan ahead in ways that could dramatically alter future prospects. It helps that in times of stress we are capable of cooperation, compassion and sacrifice, and that we possess a unique appreciation of our own vulnerability and mortality. The scientific evidence tells us that some form of contraction of the human enterprise is a biophysical necessity if we are to maintain the functional integrity of the ecosphere. Context and history therefore present us with a choice: either we accept biophysical reality, rise to our full human potential and engineer an orderly way down, or we challenge the evidence and do everything we can to maintain the status quo. Accepting biophysical reality would require the world community to plan and execute a dramatic controlled downsizing of the human enterprise. Maintaining the status quo would ultimately force nature to impose its own contraction; humanity would suffer the ugly consequences of a chaotic implosion condemning billions to suffering and death.

In 2023, the only “plans” on the official table are two variations on maintaining the status quo.

Variation 1 is standard “business-as-usual-as-usual.” This plan calls for the technologically assisted maintenance of economically extractable supplies of fossil fuels, supplemented by renewable energy, to enable maintenance of the economic status quo at least for several decades, based on the assumption that we can cope with any negative feedback when it occurs. Variation 1, which seems to be the default position of governments, would continue to grow the economy, exacerbate inequity, waste resources, precipitate runaway climate change, gut the ecosphere and undermine crucial life-support functions. It has a high probability of generating socio-geo-political chaos and the collapse of global civilization.

Variation 2 is “business-as-usual-by-alternative-means.” With the ostensible goal of avoiding the worst effects of climate change (but still not acknowledging overshoot), this plan would implement an all-out renewable energy strategy quantitatively sufficient to maintain current levels of population and material growth. This option is the dream of renewable energy and Green New Deal advocates. Arguably, it is not technically feasible in a climate-friendly time frame.²³ It would not really halt climate change and would generate the same negative social and ecological impacts as Variation 1: socio-geo-political chaos and the collapse of global society. Both variations suggest that humanity’s technohubris is exceeded only by collective denial and ignorance of systems behaviour.

The as-yet-unacceptable alternative – acknowledging overshoot and recognizing that a major reduction of both population and economic throughput (consumption and pollution) is the only way to eliminate it – is barely beginning to take form. For example, in his book Managing without Growth, Peter A. Victor explores realistic possibilities of living without economic growth, while the degrowth movement contemplates simpler, localized lifestyles, much reduced production and consumption, and greater social equality – but not reduced populations.²⁴

Full realization of the controlled contraction option requires a deeper dive beginning with a personal and cultural – indeed, “civilizational” – transformation of the fundamental values, beliefs, assumptions and attitudes that underpin neoliberal/capitalist industrial society. Crucially, the new cultural narrative must acknowledge that the human enterprise is a fully dependent subsystem of the nongrowing ecosphere that we ourselves are destroying. This, in turn, demands a shift away from the prevailing obsession with material growth (quantitative increase) and technological efficiency. Instead, we would pursue true development (qualitative betterment) – which would include improvements in nature reserves, public facilities, health care, education and opportunities for personal exploration – and greater equity, all on a much reduced scale. The world must also formally acknowledge that unsustainability is a collective problem requiring collective solutions: the present individualistic competitive race to mutual destruction must give way to unprecedented international cooperation in developing an inclusive survival plan.

In short, the continuity of civilization requires a cooperative, planned major contraction of both the material economy and human populations. The overall goal must be to establish and maintain the necessary conditions for a smaller human family (one to two billion people) to enjoy both economic and ecological security through “one-planet living.” In an earlier article, I outlined examples of policy directions consistent with this change of course.²⁵ People will learn to thrive on less and live more justly in a “steady-state” relationship with nature,²⁶ well within the remaining regenerative and assimilative capacities of the ecosphere (see figure 3). Can there possibly be a more riveting intellectual and practical challenge?

Of course, not all problems are solvable at a global scale. To be brutally clear-eyed, the prospect that our increasingly fractious world community will happily collaborate to achieve the one-planet goal is not the brightest star in the constellation of possible human futures. Failure would indeed be tragic. If the world’s nations cannot come together to fully engage their common fate, humanity will proclaim that it has no more practical intelligence or conscious moral agency when it comes to its own inclusive survival than any other species in overshoot on the brink of collapse.

Thankfully there is always some good news. Having long since learned “the way,” Tikopean society, at least, might well continue to thrive for another three millennia, regardless of what happens elsewhere.


¹  Jared Diamond, Collapse: How Societies Choose to Fail or Succeed (Penguin, 2005).

² Helen Kopnina and Haydn Washington, Discussing Why Population Growth is Still Ignored or Denied, Chinese Journal of Population Resources and Environment, Vol. 14, No. 2 (2016), pp. 133–43. For a recent example that attacks and misrepresents me and my coauthor, see Cynthia Kaufman, We Can Solve the Climate Crisis without Worrying about Population, Common Dreams, September 25, 2022.

³ Worldometer, World Population Projections (2023).

⁴ William E. Rees, Ecological Economics for Humanity’s Plague Phase, Ecological Economics, Vol. 169 (2020), Article 106519.

⁵ Max Roser, Economic Growth, Our World in Data (2019); William R. Catton, Overshoot: The Ecological Basis of Revolutionary Change (University of Illinois Press, 1982).

⁶ Yinon M. Bar-On, Rob Phillips and Ron Milo, The Biomass Distribution on Earth, Proceedings of the National Academy of Sciences, Vol. 115, No. 25 (2018), pp. 6506–11. See also Vaclav Smil, Harvesting the Biosphere: The Human Impact, Population and Development Review, Vol. 37, No. 4 (2011), pp. 613–36; The Overpopulation Project, A Foundation on the Right Track, March 1, 2022.

⁷ R.E.A. Almond, M. Grooten and T. Petersen, eds., Living Planet Report 2020: Bending the Curve of Biodiversity Loss (WWF International, 2020).

⁸ Megan K. Seibert and William E. Rees, Through the Eye of a Needle: An Eco-Heterodox Perspective on the Renewable Energy Transition, Energies, Vol. 14, No. 15 (2021), 4508.

⁹ William E. Rees, Ecological Footprint, Concept of, in Simon A. Levin, ed., Encyclopedia of Biodiversity, 2nd ed., Vol. 2 (Academic Press, 2013), pp. 701–13.

¹⁰ Global Footprint Network, Country Trends (World.

¹¹ Ibid.

¹² On the basis of national per capita GDP, the World Bank categorizes countries into four groups: low income, lower-middle income, upper-middle income, and high income.

¹³ Global Footprint Network, Country Trends (World).

¹⁴ Paul R. Ehrlich and Anne H. Ehrlich, “It’s the Numbers, Stupid!”, in Jenny Goldie and Katharine Betts, eds., Sustainable Futures: Linking Population, Resources and the Environment (CSIRO Publishing, 2014); Paul R. Ehrlich and John P. Holdren, Impact of Population Growth, Science, Vol. 171, No. 3977 (1971), pp. 1212–17.

¹⁵ United Nations, Department of Economic and Social Affairs, Statistics Division, Ensure Sustainable Consumption and Production Patterns, SDG #12: Responsible Consumption and Production (2019); Thomas O. Wiedmann, Heinz Schandl, Manfred Lenzen, Daniel Moran, Sangwon Suh, James West and Kalichiro Kanemoto, The Material Footprint of Nations, Proceedings of the National Academy of Sciences, Vol. 112, No. 20 (2013), pp. 6271–76.

¹⁶ Hannah Ritchie and Max Roser, Land Use, Our World in Data (2019); Trading Economics, World – Arable Land (Hectares per Person).

¹⁷ Richard Wilkinson and Kate Pickett, The Spirit Level: Why Equality is Better for Everyone (Penguin, 2010).

¹⁸ Business Council for Sustainable Development, Getting Eco-Efficient: Report of the BCSD First Antwerp Eco-Efficiency Workshop (November 1993), p. 10.

¹⁹ For example, Stefan Bringezu, Possible Target Corridor for Sustainable Use of Global Material Resources, Resources, Vol. 4, No. 1 (2015), pp. 25–54; Institute for Global Environmental Strategies, 1.5-Degree Lifestyles: Targets and Options for Reducing Lifestyle Carbon Footprints (2019).

²⁰ Marc E. Pratarelli, Myopic Man: On the Nature and Universality of Human Self-Deception and its Long-Term Effects on our Environment (Medici Publishing, 2008).

²¹ Antonio Damasio, Descartes’ Error: Emotion, Reason and the Human Brain (Avon, 1994); Bruce E. Wexler, Brain and Culture: Neurobiology, Ideology and Social Change (MIT Press, 2006).

²² Rees, “Ecological Economics”; William E. Rees, The Fractal Biology of Plague and the Future of Civilization, Journal of Population and Sustainability, Vol. 5, No. 1 (2020), pp. 15–30.

²³ Seibert and Rees, “Through the Eye of a Needle.”

²⁴ Peter A. Victor, Managing without Growth: Slower by Design, not Disaster, 2nd ed. (Edward Elgar, 2019); Research and Degrowth, Definition (2022).

²⁵ Rees, “Ecological Economics.”

²⁶ See Herman E. Daly, Steady-State Economics, 2nd ed. (Island Press, 1991).