Living on a Borrowed Earth
Why humanity uses 1.7 planets' worth of resources and what mindful sceptics need to know
You're standing in front of your fridge at midnight, knowing you should close the door but unable to stop staring at that leftover pizza. Now imagine 8 billion people doing the equivalent with Earth's resources. Welcome to ecological overshoot.
When I was a bushy-tailed research student in the 1980s, life was a breeze that flew by without a thought. For me, it was a time of naivety disguised as the fearlessness of youth.
Sometimes I had to make some decisions, but fortunately, most were trivial, and few animals were harmed. In my case, this was a quirk of the University ethics committee. They decided that the invertebrates that were the subject of my PhD experiments were not animals. Go figure.
My research, which I imagined was significant, attempted to build evidence for the importance of competition for food in the population biology of woodlice.
This idea, density-dependence, was very trendy at the time.
And you can see why.
Some basic ecology
In ecology, density dependence refers to how a population's per capita growth rate (birth and death rates) is affected by its density, the number of individuals per unit area or volume.
Negative density dependence is the most common and occurs as population density increases. Factors like competition for resources (food, water, space, mates), increased predation, and the easier spread of disease become more intense. These factors lead to a decrease in birth rates and/or an increase in death rates, ultimately slowing down population growth.
This crucial mechanism helps regulate population size and often leads to logistic growth curves, where populations eventually stabilise around a carrying capacity.
Long story short, this is what I found in the woodlice I studied.
Positive density-dependence, also known as the Allee effect, happens at very low population densities, when an increase in density facilitates population growth. This might occur if individuals need several others for successful reproduction (e.g., finding mates), cooperative hunting, or defence against predators.
Early humans would have benefited from the Allee effect.
Our ancestors discovered that cooperation was essential for survival. Larger groups could execute complex hunting strategies against megafauna, defend against predators and rival bands, ensure genetic diversity through expanded mate pools, and most crucially, create robust repositories of collective knowledge that could survive the loss of individual experts.
Groups also meant that individuals could specialise, some focusing on hunting, others on tool-making or foraging, enabling environmental modifications like shelter construction and fire management that small bands couldn't achieve. Understanding these deep cooperative roots helps explain why collaboration remains such a powerful force in human societies, even as we've scaled from small hunting bands to civilisations.
But success can be fickle.
As the number of individuals or groups increases, higher-density demands eventually encounter a resource constraint. Typically, for animals, this constraint is food, shelter, or space.
When there are not enough resources, the theory suggests that competition for resources, increased predation, and the easier spread of disease become more intense. Population growth slows, with density settling at some equilibrium level.
If this density dependence fails or is weak, a population grows beyond the resources available to sustain all the individuals; it has reached an ecological overshoot—too many individuals for the available resources and risks extinction from overexploitation.
From a selfish gene perspective, the immediate "interests" of individual genes in reproducing outweigh the long-term viability of the population. Each organism, driven by its genes' imperative to maximise its survival and reproduction, continues to reproduce at a high rate even as resources dwindle.
No "foresight" or "altruism" is encoded in the genes to benefit the collective future population. If the signals of resource scarcity (e.g., increased competition, lower individual survival) are not strong enough, or if the genetic programs for reproduction are too robust to be easily suppressed by these signals, the population will continue to expand.
This leads to an ecological overshoot because the genes are "blind" to the carrying capacity, pushing for continued individual propagation until the entire resource base collapses. This ultimately jeopardises the very existence of those same genes in future generations through population extinction.
So, when we see the massive population spike in the most intelligent, ubiquitous, and successful great ape, Homo sapiens, it begs the question of ecological overshoot and whether the rules of density dependence apply to the ‘wise man’.
Humans on the brink
In 2005, American academic and author Jared Diamond wrote a book called Collapse: How Societies Choose to Fail or Succeed. In it, Diamond defined collapse as "a drastic decrease in human population size and/or political/economic/social complexity, over a considerable area, for an extended time."
Diamond examined the stability of several past and present human societies relative to environmental fragility, relations with neighbours, political institutions, and other "input" variables.
He concluded that the collapse of the Maya, Anasazi, Easter Islanders and other past societies began only a decade or two after the society reached its peak numbers, wealth, and power because of population size, wealth, resource consumption, and waste production meant environmental impact outstripped resources.
In short, an ecological overshoot was the precursor to collapse.
In their selfish way, they persist into the next generation only if the vehicles they are in survive to reproduce successfully. If overshoot happens, there is a risk that the scramble for resources kills off the entire population.
This is one of the reasons why selfish gene theory is attractive to humans. It assumes that evolution favours regulation. If that assumption holds, overshoots are more likely to be modest, and recovery is likely.
In Collapse, Jared Diamond reminded us that humans can easily overshoot to excess, as we do with most things.
Humans are so ecologically competitive, including competitive displacement and extending the resource base through technology, that we ignore density dependence. Instead of being limited by overshoot, we find and use alternative resources.
We quickly assume that the laws of nature do not apply to us. We can have dominion and look forward to limitless economic growth.
So, how close are we to ecological overshoot?
Humanity is already at an ecological overshoot
Here is what the Earth's overshoot looked like in 2022, as estimated by the Global Footprint Network, summarised for various countries by Statista.
Bangladesh made it to Boxing Day, whilst Australia, despite being a whole continent, is done before easter.
Globally, humanity made it to 28 July 2022 on naturally renewed resources. The rest of the year, we mine the non-renewable capital.
We are in "ecological overshoot," using more resources than the Earth's ecosystems can regenerate in a year, accumulating ecological debt by depleting natural capital and emitting more carbon dioxide than our planet can absorb.
While the date has held relatively steady in recent years, it still signifies that humanity uses nature 1.7 times faster than Earth's regenerating capacity.
When did ecological overshoot start?
According to Diamond, population and societal collapse will happen a few decades after reaching peak numbers. This makes sense because competition for limited resources would take some time to translate into fewer births and more deaths, nuclear holocaust notwithstanding.
Humans are technologically advanced, and this skill makes new resources available, increases efficiency in resource use, and moves existing resources around. This makes the point when resources become limiting, challenging to predict or to determine if we have passed it already.
Here is one estimate, with demand and supply balanced in 1970, and an overshoot that has been consistent and growing since then.
If we assume this estimate is sound, then we have already had a few decades, and our numbers should be falling due to lower birth rates and higher death rates.
Globally, birth rates are indeed declining, but not by enough. The population is still growing at 8,000 per hour, and since 1970, the population has more than doubled.
So why haven’t we collapsed already?
The fossil fuel pulse
Gentlemen of the Victorian era couldn’t believe their luck. They marvelled at what the concentrated energy in coal could do with a bit of innovation and ingenuity. Before long, they were industrialising their way to colonialism.
Then, in 1859, Edwin Drake's well in Pennsylvania began the commercial exploitation of oil. Initially used for kerosene lighting, demand surged in the late 1800s with the invention and widespread adoption of the internal combustion engine and automobiles. Today, global oil consumption is hovering around 103-104 million barrels daily, an input of roughly 0.63 exajoules into the human ecology.
All density-dependent bets are void.
This "fossil fuel pulse" represents a massive, one-time burst of concentrated energy from coal, oil, and natural gas stored in the Earth for millions of years. It has fundamentally reshaped human civilisation, driving unprecedented technological advancement, economic growth, and population expansion.
Essentially, a pulse of exogenous energy rapidly raised the bar for negative density dependence. Resources rarely became limiting because there was enough energy to find, extract and convert them. Everything from minerals to meat was no longer constrained by how nature presented them.
We could eat and drink fossil fuels.
Last week, we saw what this did for average daily energy consumption from food, and now we know where it took us: to the brink of collapse.
When will ecological overshoot end?
More people, more consumption and ever more significant overshoot.
The economic system can leverage energy inputs and technology—what Nate Hagens calls our fossil fuel slaves—into food and people. The subsidy keeps us all going untethered from ecological limits.
Optimists and economic theorists believe that this energy and technology subsidy is the human superpower that allows us to ignore resource constraints. As long as there is energy to power our infrastructure and grow food, all is well. Overshoot can continue without consequence.
Realists know that this is crazy talk.
Even if new energy sources are invented and deployed to replace the polluting fossil energy, sooner or later, we run out of raw materials, space, nutrients, or water or drown in an ocean of waste products.
On the current path, overshoot ends with collapse; the unknown is when this will happen.
What a mindful sceptic thinks
There is no doubt that humans have decoupled from ecological constraints thanks to our access to fossils and technologies that provide us with a vast army of ‘slaves’ to do all our heavy lifting.
For now, we have excess energy above what nature can supply directly.
We are not decoupled from physical resources, especially water, metals, and materials, which we use to produce food and infrastructure.
Then come the tough questions.
Could we start with WTF? Or perhaps more politely, what are we thinking?
Humanity is on borrowed time and resources, and there is not enough ecological capacity within the planet to maintain current energy and resource use levels and absorb the waste it generates. It is not about paying back what we borrowed, but just slowing down to breathe.
Here are five more nuanced questions borrowed from William E Rees, Professor Emeritus at the University of British Columbia and former director of the School of Community and Regional Planning.
What weaknesses inherent in existing ‘environmental economics’ actually facilitate ecosystem degradation and overshoot?
Can the damaged exosphere sustainably support yet another two billion humans plus a doubling of GWP and various forms of energy/material demand, as is expected by mid-century?
What eco-economic tools and policies help might maintain a satisfactory quality of life while implementing a planned contraction of planet-depleting economic activities and populations?
What circumstances promote people’s capacity for cooperation, community building and short-term sacrifice to achieve mutually beneficial future ends (e.g., survival)?
How can ecological economics help identify efficient policies to regenerate key ecosystems and maintain essential life-support functions, including a predictably stable livable climate?
Our answers.
We are oblivious to the ecological consequences of our economic system even as we stay wedded to it on our endless path to development.
No, the biosphere cannot support our current path.
How about universal food income? More on this later.
Ironically, collapse.
Start with soil carbon sequestration and a reduction in fertiliser use.
Finding Our Way Forward
When I lugged the dozens of soil cores to the extractor bays to count the woodlice, I never imagined I was studying a preview of humanity's greatest challenge.
Those tiny crustaceans obey fundamental ecological principles as populations regulate gracefully. Sometimes, they crash spectacularly, and occasionally, they find ways to adapt that nobody predicted.
Today, as humans try to avoid, or is it ignore, density dependence on a planetary scale, I find myself returning to that same spirit of scientific curiosity mixed with humble uncertainty.
Yes, we're in ecological overshoot.
Yes, the fossil fuel pulse that enabled our remarkable population explosion is finite.
But a crisis often catalyses innovation in ways we cannot anticipate.
Obviously, we're consuming Earth's resources faster than they regenerate. But mindful scepticism isn't about accepting doom or denying reality.
It's about asking better questions.
What if our awareness of overshoot is itself the beginning of a new kind of regulation? What if human consciousness, when properly informed, can substitute for the brutal feedback loops that govern other species?
Here's my challenge to you.
Apply the same rigorous curiosity you'd bring to any scientific question to overshoot. What would a thoughtful experiment in sufficiency look like?
Remember, we're not trying to solve ecological overshoot in our individual choices; we're developing the practical wisdom and collective consciousness to regulate ourselves before the environment does it.
Mindful Momentum
The Mindful Consumption Pause
Before making any non-essential purchase this week, take three conscious breaths and ask yourself two questions…
Is this addressing a genuine need or a manufactured want?
What would happen if I waited 24 hours before deciding?
Don't aim to change your behaviour immediately, practice the pause and notice what insights arise about your relationship with consumption and the stories you tell yourself about necessity.
Key Points
Ecological overshoot occurs when resource consumption exceeds what ecosystems can regenerate, typically triggering density-dependent regulation in natural populations. In normal circumstances, when animal populations grow beyond available resources, competition intensifies and population growth slows through reduced birth rates and increased mortality. However, humans bypass these natural regulatory mechanisms through technological advancement and access to concentrated energy sources, raising questions about whether ecological principles still apply to modern civilisation.
Humanity currently consumes resources at 1.7 times the rate Earth's ecosystems can regenerate, with wealthy nations depleting their annual renewable resource allocation within the first few months of each year. Global calculations show that by late July each year, human demand has already exceeded what the planet can sustainably provide for twelve months. Countries like Australia exhaust their ecological budget by March, while nations like Bangladesh make their resources last until December, highlighting dramatic inequalities in consumption patterns.
The fossil fuel pulse has temporarily masked ecological limits by providing unprecedented access to concentrated energy stored over millions of years. This energy subsidy has enabled dramatic population growth from around 1 billion people in 1800 to over 8 billion today, while simultaneously powering industrial agriculture, global supply chains, and resource extraction technologies. The availability of coal, oil, and natural gas raised the ceiling on resource constraints, allowing human civilisation to operate beyond what renewable energy sources alone could support.
Current trajectories suggest that without significant changes, ecological overshoot will eventually result in civilizational collapse similar to historical examples like the Maya and Easter Island societies. The combination of declining fossil fuel availability, degraded ecosystems, climate change impacts, and continued population growth creates conditions where the temporary reprieve from ecological limits may end.
Curiosity Corner
This issue of the newsletter is all about…
Humanity currently consumes Earth's resources faster than they can regenerate, challenging mindful sceptics to understand how fossil fuels have temporarily allowed our species to bypass the natural population controls that regulate all other life on the planet.
5 Better Questions from this issue of the newsletter…
What evidence would convince me that humans are still subject to ecological limits despite our technological advantages?
This question is better because it challenges the assumption of human exceptionalism while requiring the questioner to define what evidence they would accept, preventing denial and catastrophizing.
How might my personal consumption choices reflect the psychological drivers enabling civilizational overshoot?
This question is better because it connects individual behaviour to systemic patterns, encouraging self-reflection without falling into either guilt or helplessness about global problems.
What are the specific mechanisms by which fossil fuel energy has masked ecological feedback loops, and which ones might reassert themselves first?
This question is better because it moves beyond simply acknowledging the fossil fuel subsidy to understanding how it operates and where vulnerabilities might emerge.
How can I distinguish between technological solutions that genuinely address overshoot versus those that simply shift the problem elsewhere?
This question is better because it requires critical evaluation of proposed solutions rather than accepting them at face value, which is essential for avoiding false hope or misguided optimism.
What would a mindful approach to ecological overshoot look like that neither minimises the severity nor leads to paralysis?
This question is better because it seeks a balanced response that integrates both the analytical and mindful components of scepticism, focusing on practical wisdom rather than just information gathering.
In the next issue
Did you know that we have built a global food system designed to gratify our evolutionary impulses, not nourish our bodies? Cheap calories win. Nutrients lose.
And the result isn’t just obesity or diabetes.
We have created a civilisation that outsources its metabolism to an industrial complex, confusing appetite with sustenance.
In the next newsletter issue, we follow the logic of this system to its endpoint. Why are we surrounded by abundance and yet malnourished? How did a species once wired for survival become complicit in its own decline? And what happens when we can’t tell the difference between being full and being fed?
Markets aren’t broken. They’re working perfectly. That’s the problem.
...be a mindful sceptic.