The purpose of this article is to advance an appropriate procreational ethics for governments and international agencies in late-stage, modern techno-industrial (MTI) societies. H. sapiens is in ecological overshoot, permanently annihilating thousands of other species and reducing the long-term human carrying capacity of Earth. MTI nations are ‘living out of’ multi-layered social constructs, including growth-demanding economic and population paradigms, that are fundamentally incompatible with biophysical reality. A deluded sense of techno-prowess, combined with selective ignorance and a weak moral compass, contribute to our growing existential crisis. In present circumstances, the inexorable workings of the Entropy Law virtually guarantee that modern humans consume and pollute (‘dissipate’) the biophysical basis of their own existence. The MTI world’s growing capacity for self-annihilation endangers not only those alive today, but also future generations. Remarkably, while the sheer weight of human numbers is at the heart of our predicament, pronatalism is on the rise and political correctness has long prohibited rational discussion of ‘the population question’. We discuss elements of this conundrum and argue that achieving eco-stability requires attention to the sheer number and still-growing population of consumers in addition to excessive energy/material consumption. It is impossible to envisage a secure future for humanity and the environment unless we overcome the population taboo and adopt an antinatalism-inspired procreative ethics. The world needs a developmental paradigm that fully considers the role of human population dynamics both in creating humanity’s eco-predicament and in resolving it.

Most urban sustainability efforts focus on aspects of climate change and emissions reductions mostly involving technological fixes. These techno-fixes involve massive capital investment and are ‘sold’ to society on the basis of profit-making potential and continuing economic growth, i.e., they designed to extend the unsustainable status quo by alternative means. This orientation is based on a faulty narrative that ignores crucial elements of human evolution, far-from-equilibrium thermodynamics, and ecological limits. While global heating is a potentially horrific problem, it is merely one major co-symptom of the real existential threat, ecological overshoot—urban industrial society is depleting and dissipating the biophysical basis of its own existence. From this perspective, the climate focus is a wasteful distraction. It is not reversing global heating and is actually worsening overshoot and its cause, the excessive scale of urban industrial society. Using natural law and material realities this paper validates the claim that contemporary urbanization is inherently unsustainable. Cities are massive far-from-equilibrium dissipative structures that grow and maintain themselves by extracting energy and material resources from their environments and ‘dissipating’ an equivalent quantity of degraded waste back into those environments. In the process, they necessarily generate exploitive ecological footprints orders of magnitude larger than their built-up or political areas. In short, modern cities flourish at the expense of the entropic disordering of the ecosphere. Corrective change is thwarted by the fact that, for most purposes including provisioning themselves, cities remain dependent on fossil fuels. This creates a genuine predicament: ‘stopping fossil fuels’ would make it impossible to supply and maintain cities, leading to contraction and social disorder, but continuing fossil fuel use (society’s current default position) exposes cities to the dire consequences of possible climate chaos. Urban sustainability requires major reductions of energy/resource consumption and pollution (i.e., ‘environmentally conscious’ low-throughput life-styles) and smaller populations. Earth cannot sustainably support eight let alone an anticipated 10 billion+ people.

Homo sapiens has evolved to reproduce exponentially, expand geographically, and consume all available resources. For most of humanity’s evolutionary history, such expansionist tendencies have been countered by negative feedback. However, the scientific revolution and the use of fossil fuels reduced many forms of negative feedback, enabling us to realize our full potential for exponential growth. This natural capacity is being reinforced by growth-oriented neoliberal economics—nurture complements nature. Problem: the human enterprise is a ‘dissipative structure’ and sub-system of the ecosphere—it can grow and maintain itself only by consuming and dissipating available energy and resources extracted from its host system, the ecosphere, and discharging waste back into its host. The population increase from one to eight billion, and >100-fold expansion of real GWP in just two centuries on a finite planet, has thus propelled modern techno-industrial society into a state of advanced overshoot. We are consuming and polluting the biophysical basis of our own existence. Climate change is the best-known symptom of overshoot, but mainstream ‘solutions’ will actually accelerate climate disruption and worsen overshoot. Humanity is exhibiting the characteristic dynamics of a one-off population boom–bust cycle. The global economy will inevitably contract and humanity will suffer a major population ‘correction’ in this century.

Ecological footprint analysis (EFA) estimates the exclusive area of productive ecosystems that any specified human population requires to produce the bio-resources it consumes and assimilate the (mostly carbon) waste it produces. The eco-footprint (EF) is the only sustainability indicator that enables comparisons of human demand for ecosystems' goods and services with the available supply of biocapacity (productive ecosystem area). EFA reveals that the global human enterprise is in overshoot, consuming renewable resources faster than ecosystems regenerate and filling natural waste sinks beyond capacity. Most of the world's nations have long overshot their domestic carrying capacities; they survive on imports and run large ecological deficits with surplus countries and the global commons. Similarly, cities are all overshoot, utterly dependent for survival on ecosystems scattered all over the planet. Overshoot is a meta-problem—global warming, plunging biodiversity, tropical deforestation, soil/land degradation, pollution of air, land and waters, etc., etc., are all co-symptoms. Left uncorrected, overshoot is a terminal condition; eco-footprinting indicates that global urban civilization is on track for controlled contraction or chaotic collapse—our choice.

I will begin by summarizing what I am going to say as a primer for what is to come. I argue that modern cities could not have developed at all without fossil fuels and that today’s urban civilization will find it difficult to persist without fossil fuels. Of course, there is a catch. Fossil fuels are the principal enablers of ‘ecological overshoot’ and its many symptoms, including climate change. Mainstream efforts to address climate change will not only not fix climate change but will also worsen overshoot. Unfortunately, overshoot is a fatal condition. Unless we address overshoot directly, the remaining life of modern urban civilization may well be nasty, brutish and short. Current thinking about urbanization ignores overshoot and is taking us precisely down this Hobbesian pathway. This may seem like a sweeping overstatement, but it does describe humanity’s current trajectory. A dramatic transformation in thinking is essential for urban sustainability. Now to elaborate, most governments and mainstream international agencies think that climate change is the major ‘environmental’ issue and that we can halt climate change. People in highincome countries generally seem to believe that the future will unfold as a technology-enhanced extension of the relatively recent past. We project urban populations to increase to 6.7 billion by 2050. There are supposedly going to be 43 mega cities with more than 10 million inhabitants by 2030 etc. I argue that all such conventional projections are simplistically reductionist. The mainstream prognosis ignores energy and resource constraints, deteriorating geopolitics and the accelerating degradation of the ecosphere. Most urban sustainability efforts are single-focused on mitigating climate change or on so-called ‘smart-city’ initiatives. There is virtually no consideration of the concept of ecological carrying capacity or the need for high-income city dwellers in particular to achieve material standards that are consistent with living on a single planet (i.e. we must reduce consumption to be compatible with ‘one-planet living’). Even those cities that are focusing on reversing climate change are generally falling short in reducing their carbon dioxide emissions. Urbanists commit another major perceptual error. We frequently read that ‘urbanized land constitutes only ~3% of the total land area’ (excluding Antarctica and Greenland), as if Earth were empty and urbanization is not a major factor in global change. But this is, again, static simplicity. Cities are not just dots on a map but also dynamic living systems. An urban ecosystem is globally dispersed far beyond the city proper. A city’s true ecological footprint (EF) is the total area of productive ecosystems that its population requires, on a continuous basis, to produce the bio resources that it consumes and to assimilate its carbon and other wastes wherever on earth those ecosystems may be located. Typically, the eco-footprint of a large modern city is a hundred to a thousand times larger than the geographic or built-up area of that city. A city’s EF is the actual functional area of productive land/water on Earth occupied ecologically by that city’s population. Let us take a typical case, Tokyo, to illustrate ecological reality (it is not quite typical as Tokyo is the world’s largest city). With a population of 38 million – which, by the way, is roughly the population of Canada – and a per capita EF of 4.5 global average hectares (gha), Tokyo’s de facto

Previously, anthropogenic ecological overshoot has been identified as a fundamental cause of the myriad symptoms we see around the globe today from biodiversity loss and ocean acidification to the disturbing rise in novel entities and climate change. In the present paper, we have examined this more deeply, and explore the behavioural drivers of overshoot, providing evidence that overshoot is itself a symptom of a deeper, more subversive modern crisis of human behaviour. We work to name and frame this crisis as 'the Human Behavioural Crisis' and propose the crisis be recognised globally as a critical intervention point for tackling ecological overshoot. We demonstrate how current interventions are largely physical, resource intensive, slow-moving and focused on addressing the symptoms of ecological overshoot (such as climate change) rather than the distal cause (maladaptive behaviours). We argue that even in the best-case scenarios, symptom-level interventions are unlikely to avoid catastrophe or achieve more than ephemeral progress. We explore three drivers of the behavioural crisis in depth: economic growth; marketing; and pronatalism. These three drivers directly impact the three 'levers' of overshoot: consumption, waste and population. We demonstrate how the maladaptive behaviours of overshoot stemming from these three drivers have been catalysed and perpetuated by the intentional exploitation of previously adaptive human impulses. In the final sections of this paper, we propose an interdisciplinary emergency response to the behavioural crisis by, amongst other things, the shifting of social norms relating to reproduction, consumption and waste. We seek to highlight a critical disconnect that is an ongoing societal gulf in communication between those that know such as scientists working within limits to growth, and those members of the citizenry, largely influenced by social scientists and industry, that must act.

The human enterprise is in overshoot, depleting essential ecosystems faster than they can regenerate and polluting the ecosphere beyond nature’s assimilative capacity. Overshoot is a meta-problem that is the cause of most symptoms of eco-crisis, including climate change, landscape degradation and biodiversity loss. The proximate driver of overshoot is excessive energy and material ‘throughput’ to serve the global economy. Both rising incomes (consumption) and population growth contribute to the growing human eco-footprint, but increasing throughput due to population growth is the larger factor at the margin. (Egregious and widening inequality is a separate socio-political problem.) Mainstream approaches to alleviating various symptoms of overshoot merely reinforce the status quo. This is counter-productive, as overshoot is ultimately a terminal condition. The continuity of civilisation will require a cooperative, planned contraction of both the material economy and human populations, beginning with a personal to civilisational transformation of the fundamental values, beliefs, assumptions and attitudes underpinning neoliberal/capitalist industrial society.

The human enterprise is in overshoot; we exceed the long-term carrying capacity of Earth and are degrading the biophysical basis of our own existence. Despite decades of cumulative evidence, the world community has failed dismally in efforts to address this problem. I argue that cultural evolution and global change have outpaced bio-evolution; despite millennia of evolutionary history, the human brain and associated cognitive processes are functionally obsolete to deal with the human eco-crisis. H. sapiens tends to respond to problems in simplistic, reductionist, mechanical ways. Simplistic diagnoses lead to simplistic remedies. Politically acceptable technical ‘solutions’ to global warming assume fossil fuels are the problem, require major capital investment and are promoted on the basis of profit potential, thousands of well-paying jobs and bland assurances that climate change can readily be rectified. If successful, this would merely extend overshoot. Complexity demands a systemic approach; to address overshoot requires unprecedented international cooperation in the design of coordinated policies to ensure a socially-just economic contraction, mostly in high-income countries, and significant population reductions everywhere. The ultimate goal should be a human population in the vicinity of two billion thriving more equitably in ‘steady-state’ within the biophysical means of nature.

Humanity's demand for resources exceeds annually the Earth's productive capacity (EPC), defined as the total regenerative and assimilative capacities of our planet. This article asks what role is given to living within EPC by cities in the quest for urban sustainability and how comprehensively are high-income cities assessing and reducing their impact. Our methodology comprises three steps: 1. urban sustainability literature review, 2. verification of sustainability frameworks and indicators aligned with the goal of living within earth's productive capacity, 3. study of high-income cities that have intentionally reduced their carbon footprint over the 1990-2020 period. Eleven sustainability frameworks were identified as fully aligned with the goal of living within EPC. Most cities work with indicators related to climate change; however, a singular focus risks underestimating cities' total global ecological impacts. A shortlist of 24 cities who achieved at least a 15% reduction in their carbon footprint between 1990 and 2020 was developed. These reductions were insufficient in magnitude to meet climate stability goals. To achieve a just transition towards living within EPC, cities must confront their overconsumption by using EPC compliant tools and frameworks, and develop specific reduction targets considering global limits, local responsibilities, and capacities to mitigate.

Using an eight-dimensional indicator index, we evaluate the trajectories of resilience of 160 countries over 20 years. Our highly-granular analysis of the current state of the world shows what must happen to control climate change and switch from quantitative to qualitative growth. Assessing the resilience of a country is a complex task prone to opacity and subjectivity. The challenge is to strike a balance between the Earth's biophysical limits and socioeconomic models designed to ignore them. Here we propose a resilience index composed of eight indicators of socioeconomic status (GDP and HDI), natural resources and population (arable land and water resources per capita), energy (supply and renewables), and environmental impacts (greenhouse gas emissions and material footprint). We show that the socioeconomic indicators have improved, while natural resources have been depleting and environmental impacts worsening. We need to reduce the current material footprint 1.5-fold. Average CO2 emissions per capita must drop by an order of magnitude. Furthermore, population growth and political instability seem to undermine resilience score of a country.

Humanity must commit to transformative change on all levels in order to address the climate emergency and biodiversity collapse. In particular, stabilizing and ultimately reducing the human population size is necessary to ensure the long-term wellbeing of our species and other life on Earth. We show how this transition can be accomplished in an equitable framework that promotes human rights. Specifically, we issue a global appeal for women and men to have at most one child and call for policy-makers to implement population policies that improve education for girls and young women and ensure the availability of high-quality family-planning services.

This paper exposes the many flaws in the article “Through the Eye of a Needle: An Eco-heterodox Perspective on the Renewable Energy Transition, authored by Siebert and Rees and recently published in Energies as a Review. Our intention in submitting this critique is to expose and rectify the original article’s non-scientific approach to the review process that includes selective (and hence biased) screening of the literature focusing on the challenges related to renewable energies, without discussing any of the well-documented solutions. In so doing, we also provide a rigorous refutation of several statements made by a Seibert–Rees paper, which often appear to be unsubstantiated personal opinions and not based on a balanced review of the available literature.

We add to the emerging body of literature highlighting cracks in the foundation of the mainstream energy transition narrative. We offer a tripartite analysis that re-characterizes the climate crisis within its broader context of ecological overshoot, highlights numerous collectively fatal problems with so-called renewable energy technologies, and suggests alternative solutions that entail a contraction of the human enterprise. This analysis makes clear that the pat notion of “affordable clean energy” views the world through a narrow keyhole that is blind to innumerable economic, ecological, and social costs. These undesirable “externalities” can no longer be ignored. To achieve sustainability and salvage civilization, society must embark on a planned, cooperative descent from an extreme state of overshoot in just a decade or two. While it might be easier for the proverbial camel to pass through the eye of a needle than for global society to succeed in this endeavor, history is replete with stellar achievements that have arisen only from a dogged pursuit of the seemingly impossible.

‘We have kicked the can down the road once again – but we are running out of road.’ – Rachel Kyte, Dean of Fletcher School at Tufts University. We, in our capacities as scientists, economists, governance and policy specialists, are shifting from warnings to guidance for action before there is no more ‘road.’ The science is clear and irrefutable; humanity is in advanced ecological overshoot. Our overexploitation of resources exceeds ecosystems’ capacity to provide them or to absorb our waste. Society has failed to meet clearly stated goals of the UN Framework Convention on Climate Change. Civilization faces an epochal crossroads, but with potentially much better, wiser outcomes if we act now. What are the concrete and transformative actions by which we can turn away from the abyss? In this paper we forcefully recommend priority actions and resource allocation to avert the worst of the climate and nature emergencies, two of the most pressing symptoms of overshoot, and lead society into a future of greater wellbeing and wisdom. Humanity has begun the social, economic, political and technological initiatives needed for this transformation. Now, massive upscaling and acceleration of these actions and collaborations are essential before irreversible tipping points are crossed in the coming decade. We still can overcome significant societal, political and economic barriers of our own making. Previously, we identified six core areas for urgent global action – energy, pollutants, nature, food systems, population stabilization and economic goals. Here we identify an indicative, systemic and time-limited framework for priority actions for policy, planning and management at multiple scales from household to global. We broadly follow the ‘Reduce-Remove-Repair’ approach to rapid action. To guide decision makers, planners, managers, and budgeters, we cite some of the many experiments, mechanisms and resources in order to facilitate rapid global adoption of effective solutions. Our biggest challenges are not technical, but social, economic, political and behavioral. To have hope of success, we must accelerate collaborative actions across scales, in different cultures and governance systems, while maintaining adequate social, economic and political stability. Effective and timely actions are still achievable on many, though not all fronts. Such change will mean the difference for billions of children and adults, hundreds of thousands of species, health of many ecosystems, and will determine our common future.

We have reached a unique juncture in human ecological history, one requiring a radical reconfiguration of planning values and goals. The "ecological footprint" of the global economy is already larger than the planet, yet a quarter of humanity still lives in poverty, the human family is expanding by 90 million a year, and material demands everywhere are rising. An unlikely tenfold reduction in the energy and material intensity of economic activity would be required to accommodate anticipated economic growth safely, posing an enormous challenge to planners in facilitating the transition to sustainability. Failure enhances the considerable possibility of global disaster.

At the time of writing, the CoViD-19 pandemic was in its second wave with infections doubling every several days to two weeks in many parts of the world. Such geometric (or exponential) expansion is the hallmark of unconstrained population growth in all species ranging from submicroscopic viral particles through bacteria to whales and humans; this suggests a kind of ‘fractal geometry’ in bio-reproductive patterns. In nature, population outbreaks are invariably reversed by the onset of both endogenous and exogenous negative feedback – reduced fecundity, resource shortages, spatial competition, disease, etc., serve to restore the reference population to below carrying capacity, sometimes by dramatic collapse. H. sapiens is no exception – our species is nearing the peak of a fossil-fueled ~200 year plague-like population outbreak that is beginning to trigger serious manifestations of negative feedback, including climate change and CoViD-19 itself. The human population will decline dramatically; theoretically, we can choose between a chaotic collapse imposed by nature or international cooperation to plan a managed, equitable contraction of the human enterprise.