Overpopulation

"We’ve just welcomed the 8 billionth member of the human race on this planet. That’s a wonderful birth of a baby, of course. But we need to understand that the more people there are, the more we put the Earth under heavy pressure. As far as biodiversity is concerned, we are at war with nature. We need to make peace with nature. Because nature is what sustains everything on Earth … the science is unequivocal."

"Babies are the enemies of the human race... Let's consider it this way: by the time the world doubles its population, the amount of energy we will be using will be increased sevenfold which means probably the amount of pollution that we are producing will also be increased sevenfold. If we are now threatened by pollution at the present rate, how will we be threatened with sevenfold pollution… distributed among twice the population? We'll be having to grow twice the food out of soil that is being poisoned at seven times the rate."

"It's going to destroy it all. I use what I call my bathroom metaphor. If two people live in an apartment, and there are two bathrooms, then both have what I call freedom of the bathroom, go to the bathroom any time you want, and stay as long as you want to for whatever you need. And this to my way is ideal. And everyone believes in the freedom of the bathroom. It should be right there in the Constitution. But if you have 20 people in the apartment and two bathrooms, no matter how much every person believes in freedom of the bathroom, there is no such thing. You have to set up, you have to set up times for each person, you have to bang at the door, aren't you through yet, and so on. And in the same way, democracy cannot survive overpopulation. Human dignity cannot survive it. Convenience and decency cannot survive it. As you put more and more people onto the world, the value of life not only declines, but it disappears. It doesn't matter if someone dies."

"We are a plague on the Earth. It’s coming home to roost over the next 50 years or so. It’s not just climate change; it’s sheer space, places to grow food for this enormous horde. Either we limit our population growth, or the natural world will do it for us, and the natural world is doing it for us right now."

"The success of modern medicine is today so great, that millions of people are kept alive - if not cured - who in earlier days, and with less scientific aptitude, would normally have died. In this developed skill and knowledge, and in this aptitude in the care of the physical mechanism, is today to be found a major world problem - the problem of overpopulation of the planet, leading to the herd life of humanity and the consequent economic problem - to mention only one of the incidental difficulties of this success. This "unnatural" preservation of life is the cause of much suffering, and is a fruitful source of war, being contrary to the karmic intent of the planetary Logos. With this vast problem, I cannot here deal. I can only indicate it. It will be solved when the fear of death disappears, and when humanity learns the significance of time and the meaning of the cycles."

"As we slide seamlessly from 7 billion to 8 billion humans, each generation more powerful, polluting, and destructive than the previous, I have to wonder whether one century is too much time to allow a “natural” progression into negative population growth, or whether the biodiversity damage a century like this one will inflict could be incalculable and irreversible, if not terminal for us. Think about the honey bees and hummingbirds. Think about the sudden absence of insects we are seeing all over the world, and how that soon may affect populations farther up or down the food chain. Now, Mr. Biotech Billionaire, are you serious about populating the world with thousands or millions of bicentiniarians [sic] and tricentinarians [sic]?"

"Whereas the unconscious operations and blind forces of the planet have provoked turbulent changes over the last 4.5 billion years of earth’s evolutionary history, now change is being directed by a conscious and volitional agent – "humanity." We cannot speak of humanity equally, to be sure, as the problem was caused by the industrialized capitalist West and the poorer nations who contributed least to climate crisis will be hit the hardest. But nations such as China, India, and Brazil are major contributors, and the cumulative impact of 7.5 billion people on the planet is causing extinction and collapse everywhere. The stability of the Holocene is now gone, changes are accelerating beyond our understanding and control, and chaos waits at our door."

"The geometric growth rate of humans is unprecedented and never in the history of the earth has a single species grown to such bloated proportions, completely out of balance with living systems. The problem is only worsening. On conservative estimates, the human population is expected to swell upwards to 8–10 billion by 2050, and perhaps expand significantly by 2100. Human population growth represents a crisis of the highest order, but of course, it is only one aspect of multiple crises -- including species extinction and climate change -- merging together in a perfect storm of catastrophe that forms the daunting challenges facing humanity in the Anthropocene."

"Currently, the operation of our present industrial civilization is almost wholly dependent on access to huge amounts of fossil fuels. It is important to understand that fossil fuels, especially oil, are not simply used to manufacture and propel passenger automobiles or trucks. They also facilitate the mass assembly of tractors, plows, irrigation pipes, and pumps and then turn around and power them also. They constitute the chemical base of many crucial fertilizers and pesticides. They are also the building blocks of agricultural plastics. They refrigerate perishables. In short, the modern industrial agriculture system could not function without copious amounts of fossil fuel. In the absence of fossil fuel-based industrial agriculture, world food production would plummet to a scale completely inadequate to sustain our current population size, let alone the net addition of over 80 million more people each year. The other side of the coin is that when humans co-opt the extraordinary power found in fossil fuels, we become “overpowered” – and that is how we are over-powering the Earth’s biosphere. We cannot destroy rainforests at the rate of several football fields per minute, trawl the deep oceans, attempt mass-scale aqua-culture, fragment habitat with asphalt roads, or construct miles and miles of urban sprawl without the power of fossil fuels. In summary, fossil fuels underwritten both our population size and growth and our discretionary (over)consumption."

"In my opinion, you have out-of-control population growth, and you have fewer and fewer [resources]—we are heading for the biggest train wreck our civilization has ever come across ever. Ever. And I think that within 40 or 50 years, we’ll be there. If your population curve is on an exponential growth, and the resources are on an exponential decline, what happens first is you get increases in wealth discrepancy, which means that you get rich pockets of gated communities with security guards outside them, and you get more and more poverty outside that area. And the resources go down, and people start having resource wars over water and food and agriculture and arable land, and then you have Joburg in 2050. And you can see signs of it everywhere. It’s just overpopulation and lack of resources. We just aren’t in control of our destiny."

"... Reverend THOMAS MALTHUS' prediction made in 1798—that man would reproduce himself into a condition of "misery and vice" because of the growing imbalance caused by the multiplication of his own numbers by geometric progression, while his food supply was increasing arithmetically—is as valid today as when it was made. He was a visionary and saw clearly the monster of overpopulation. The only error in his prediction was one of a "few seconds on the clock of human occupancy of the earth". We, agriculturists, can buy at most a few decades of time in which to bring population growth into successful balance with food production."

"It seems self-evident that our fundamental predicament of ecological overshoot is a direct result of humanity’s growth with too many people consuming too many resources and producing too many waste products for a finite planet dependent upon healthy ecological systems. And while this doesn’t require much explanation for those who acknowledge that we live upon a world with finite resources and limited capacity to compensate for our waste production, there are still many who believe that Homo sapiens’ rather unique cognitive abilities and technological prowess can and will ‘solve’ the many challenges we appear to be encountering as we reach and surpass the planetary limits of our relatively recent explosive growth, global expansion, and industrialisation."

"All living species must take from nature to survive, and we are no different. But unlike other species, there seems to be no end to our quest for food, comfort, shelter, sex — the fundamental necessities of survival that are now pursued in overdrive, far beyond our existential needs. We are compelled to progress, and have extracted resources from the land since we first stood on two feet. The entire twentieth century has been a revving up of this large consumptive engine, and this insatiable human striving has assaulted the very planet that sustains us. In a very short period of time, humankind, with its population explosion, industry and technology, has become an agent of immense global change. What this civilization leaves in the wake of its progress may be an opened and emptied Earth. But in performing these incursions, we also participate in the unwitting creation of gigantic monuments to our way of life."

"Global biodiversity decline is best understood as too many people consuming and producing too much and displacing other species. Wild landscapes and seascapes are replaced with people, our domestics and commensals, our economic support systems, and our trash."

"During the past hundred years, Homo sapiens population increased from 2 billion to nearly 8 billion and the United Nations (2019) projects an increase of 3 billion more by 2100, unless steps are taken to reduce this population growth. Ignoring this projected increase means ignoring a major driver of the unfolding biodiversity crisis; accepting current bloated human numbers as an appropriate status quo means accepting a biologically impoverished planet."

"Thomas Malthus, an eighteenth-century economist, once predicted that because our population size increases exponentially while our food supply increases arithmetically, our population will one day exceed our ability to sustain it. While this has now been disproven with the creation of processed foods and genetically modified organisms, [Peter] Farb’s paradox may hold true. Because Earth’s population is growing, we increase our food production. Then, because we have a surplus of food, people are more well-nourished, leading to higher life expectancies and lower infant mortality rates, and people are able to have more children. This cyclical paradox is not healthy for our planet because while we may be able to sustain our growing population’s appetites, our other important resources, such as water and oil, are dwindling. To have a sustainable population size, we should be reproducing at a replacement rate, much like Denmark and Japan are."

"Today [hu]mankind is locked into stealing ravenously from the future. Famine in the modern world must be… one of several symptoms reflecting a deeper malady of in the human condition—namely, diachronic competition, a relationship whereby contemporary well-being is achieved at the expense of our descendants. By our sheer numbers, by the state of our technological development, and by being oblivious to differences between a method that achieved lasting increments of human carrying capacity [agriculture] and one that achieves only temporary supplements [reliance on fossil fuels and other mined substances], we have made satisfaction of today's human aspirations dependent upon massive deprivation for posterity."

"We are already living on an overloaded world. Our future will be a product of that fact; that fact is a product of our past. Our first order of business, then, is to make clear to ourselves how we got where we are and why our present situation entails a certain kind of future. […] It is the story of a world that has again and again approached the condition of being saturated with human inhabitants, only to have the limit raised by human ingenuity. The first several rounds of limit-raising were accomplished by a series of technological breakthroughs that took almost two million years. These breakthroughs enabled human populations repeatedly to take over for human use portions of the earth’s total life-supporting capacity that had previously supported other species. The most recent episode of limit-raising has had much more spectacular results, although it enlarged human carrying capacity by a fundamentally different method: the drawing down of finite reservoirs of materials that do not replace themselves within any human time frame. Thus its results cannot be permanent. This fact puts mankind out on a limb which the activities of modern life are busily sawing off."

"Scarcely more than two generations had tasted the fruits of industrialization when the growth of population was still further accelerated by truly effective death control. The role of microorganisms in producing diseases was discovered. In 1865 the practice of antiseptic surgery began. It serves... as a reasonable demarcation of the beginning of an era filled with related breakthroughs in medical technology: hygienic practices, vaccination, antibiotics, etc. The total effect of this recent series of achievements has been to emancipate mankind more... from the life-curtailing effects of the invisible creatures for which human tissues used to serve as sustenance. Like other prey species newly protected from their predators, we have been fruitful and have so multiplied that we have much more than "replenished" the earth with our kind."

"People displayed either persistent ignorance of the carrying capacity concept or naive faith that carrying capacity could always be expanded, [and] that limits could always be transcended. Such an assump­tion seemed to underlie the stubborn refusal of capitalists and Marx­ists alike to acknowledge that the myth of limitlessness had, at last, become obsolete. There was also the assumption that further ad­vances in technology would necessarily enlarge carrying capacity, not reduce it. Enlargement of carrying capacity had been the role of tech­nology in the past; however… there has been a reversal of this role in the industrial era. Technology has en­larged human appetites for natural resources, thus diminishing the number of us that a given environment can support."

"[Hu]man[s]... have imagined... [themselves] to be more unlike other mammals than [t]he[y] really... [are], so when human behavior has shown these same characteristics, various other explanations have been put forth which have obscured the significance of population pressure itself. In the twentieth century, with human numbers enlarged and resource draw­down becoming significant, [hu]man[kind] went to war. [T]he[y] rioted in the streets. [T]he[y] committed more... crimes of violence. [...] [Their] political atti­tudes polarized and [t]he[y] created totalitarian governments, some of which gave license to sadistic tendencies. A generation gap widened and deepened. In spite of earnest efforts by humane activists to inhibit racism and to rectify economic inequality, disparities between people remained and animosities became more virulent. Standards of de­cency in behavior toward others and expectations of considerate self-­restraint were eroded and degraded in many places."

"We need to realize the "load" with which we humans burden the planet's ecosystems consists of more than just a population number. People living by different cultures not only reproduce at different rates; they impose very different per capita ecological impacts. Culture includes a population's technology and people's ways of organizing themselves. Each of us living in a "developed" country (i.e., industrialized far beyond anything conceivable to Malthus) has an enormously greater resource appetite and environmental impact than does each resident of a so-called "developing" country. For our grossly unsustainable manner of living, 6 billion is far too many."

"Life has now entered a . This is probably the most serious environmental problem, because the loss of a species is permanent, each of them playing a greater or lesser role in the living systems on which we all depend. The species extinctions that define the current crisis are, in turn, based on the massive disappearance of their component populations, mostly since the 1800s. The massive losses that we are experiencing are being caused, directly or indirectly, by the activities of Homo sapiens. They have almost all occurred since our ancestors developed agriculture, some 11,000 y ago. At that time, we numbered about 1 million people worldwide; now there are 7.7 billion of us, and our numbers are still rapidly growing. As our numbers have grown, humanity has come to pose an unprecedented threat to the vast majority of its living companions."

"We are in the sixth mass extinction event. Unlike the previous five, this one is caused by the overgrowth of a single species, Homo sapiens."

"Over the last century the pace of many human activities has so accelerated, and human overpopulation grown so severe, to have created a dramatic global environmental transformation. Most natural ecosystem have been highly modified or have disappeared altogether, and the abundance of wildlife has been greatly reduced."

"Our use of energy has been increasing ever since we discovered and mastered fire and developed agriculture, but mostly since we gained access to a vastly increased energy supply by extracting millions of years of stored and concentrated solar energy from the Earth’s crust in the form of fossil fuels. Combined with the development of new energy conversion techniques, this energy bonanza made it possible to lift the secular barriers to human population and output growth. The new energy sources, forms and uses that came online since the turn of the 19th century gave us access to more materials and enabled the invention of new and increasingly sophisticated exosomatic instruments (i.e. machines), which in turn made it possible to access ever more energy and matter and to transform them ever more effectively and efficiently. This resulted in a rapid rise in our total energy and material “throughput” (i.e. the flow of raw materials and energy from the biosphere’s sources, through the human ecosystem, and back to the biosphere’s sinks), which is what we commonly measure through the proxy concept of “economic growth”. This rise never stopped since then, even if the global distribution of the flows of energy and material inputs, outputs and wastes evolved over time. Our efforts to increase the “energy efficiency” of our machines and processes (i.e. reducing the amount of energy needed to perform certain tasks) never resulted in a reduction of the total energy we used, but on the contrary only contributed to create more room for increasing the rate of our consumption."

"Environmental analysts regard a sustainable human population as one enjoying a modest, equitable middle-class standard of living on a planet retaining its biodiversity and with climate-related adversities minimized. Analysts' estimate[s] of that population size vary between 2 and 4 billion people, a figure obviously well below the present 7.9."

"The situation in which we find ourselves today is unique as regards the magnitude and rate of growth of the human enterprise. The turn now being taken by the vicious circle is tremendous. […] The mastery of fire, one of humans' first instances of technological development, continues to be of paramount importance today with the burning of fossil fuels. And so the vicious circle of the development of humankind churns on, and does so with ever greater momentum due to the constantly increasing consumption of fossil fuels and metals, with only the tiniest sign of resistance in the form of the efforts of environmental organisations and green political parties."

"The population boom of the last few centuries […] was made possible by massive advances in living standards, economic growth, surpluses of food, and vastly improved public health. All of this, however, was sustained by fossil fuels. Once fossil fuel reserves peak […] production, growth, and the amenities of modern life will gradually halt. Contemporary industrial society will downgrade into a “scarcity society” that manages on minimal energy, after which it will become a “salvage society” that scrapes survival from the refuse of the defunct urban buildings, information networks, and industrial centers."

"Part of human impact on the earth relates to our swiftly growing numbers. If we do not take deliberate, conscious action to maintain a reasonable balance between the numbers of people and the environmental wealth required to sustain us, nature will make appropriate adjustments, and famine, disease, and wars-the predictable outcomes of living beyond one's environmental means, of overspending environmental capital-will ultimately force a cruel discipline."

"The key to understanding overpopulation is not population density but the numbers of people in an area relative to its resources and the capacity of the environment to sustain human activities; that is, to the area’s carrying capacity. When is an area overpopulated? When its population can’t be maintained without rapidly depleting nonrenewable resources... By this standard, the entire planet and virtually every nation is already vastly overpopulated."

"The debate regarding which individual factor, among the three key factors producing the environmental crisis, causes more damage - the size of the human population on the planet, excessive consumption of resources, or unequal/ unjust distribution of resources among countries [the wealthier countries consume much more resources, per person on average than poorer countries] - is like a debate about which contributes more to a triangle, the base or the ribs of the triangle. You can not separate the three factors. If we analyze the numbers over a relatively longer time interval, we will conclude that the size of the population has a bigger impact than consumption. On the other hand, consumption and unequal distribution are also important aspects. If we do not change these three factors all at the same time, the quality of our life will change dramatically. Today humanity is delivering a serious blow to [the rest of] nature, but it is clear that nature will deliver the final blow."

"Earth is home to millions of species. Just one dominates it. Us. Our cleverness, our inventiveness, and our activities have modified almost every part of our planet. In fact, we are having a profound impact on it. Indeed, our cleverness, our inventiveness, and our activities are now the drivers of every global problem we face. And every one of these problems is accelerating as we continue to grow towards a global population of ten billion. In fact, I believe we can rightly call the situation we're in right now an emergency – an unprecedented planetary emergency."

"We humans emerged as a species about 200,000 years ago. In geological time, that is really incredibly recent. Just 10,000 years ago, there were one million of us. By 1800, just over 200 years ago, there were 1 billion of us. By 1960, 50 years ago, there were 3 billion of us. There are now over 7 billion of us. By 2050, your children, or your children's children, will be living on a planet with at least 9 billion other people. Some time towards the end of this century, there will be at least 10 billion of us. Possibly more. We got to where we are now through a number of civilization-and society-shaping “events”; most notably, the agricultural revolution, the scientific revolution, and—in the West—the public-health revolution. These events have fundamentally shaped how we live, and have fundamentally shaped our planet. Their legacy will continue to shape our future. So we need to look at our growth and activities through the lens of these developments. One of the principal reasons for this growth was the invention of agriculture. The “agricultural revolution” enabled us to go from being hunter-gatherers to highly organized producers of food, and allowed our population to grow. A useful way to think of the development and importance of agriculture is in terms of at least three agricultural “revolutions.” The first took place over 10,000 years ago. This was the domestication of animals and the cultivation of plant types. The second agricultural revolution was between the fifteenth and nineteenth centuries. This was a revolution in agricultural productivity and the mechanization of food production. The third happened between the 1950s and 2000s; the so-called “green revolution.” But there’s another story here: the start of a fundamental transformation—of land use—by humans."

"As our numbers continue to grow, we continue to increase our need for far more water, far more food, far more land, far more transportation, and far more energy. As a result, we are now accelerating the rate at which we’re changing our climate. In fact, our activities are not only completely interconnected with, but are now also interacting with, the complex system we live on: Earth. It is important to understand how all this is connected. An increasing population accelerates the demand for more water and more food. Demand for more food increases the need for more land, which accelerates deforestation. Increasing demand for food also increases food processing and transportation. All of these accelerate the demand for more energy. This then accelerates greenhouse gas emissions, principally CO2 and methane, which further accelerate climate change. As climate change accelerates, it increases stress on water, food, and land. And at the same time, an increasing population also accelerates stress on water, food, and land. In short, as population increases, and as economies grow, stress on the entire system accelerates sharply."

"Saying “Don’t have children” is utterly ridiculous. It contradicts every genetically coded piece of information we contain, and (at least in their conception) one of the most important (and fun) impulses we have. That said, the worst thing we can continue to do—globally—is have children at the current rate. Even if a global nuclear power program were set up, even if geoengineering somehow took care of the climate-change problem, and even if we consumed less, we’d still at some point hit a brick wall if the human population continues to grow at anything like its current rate. We all know there’s a link between educating women in the developing world and reducing the birth rate. But despite this, and despite contraception being free in a number of countries where population is increasing, average birth rates are still three, five, or even seven children per woman. According to the United Nations, Zambia’s population is projected to increase by 941 percent by the end of the century. The population of Nigeria is projected to grow by 349 percent—to 730 million people. Afghanistan by 242 percent, The Democratic Republic of Congo by 213 percent, Gambia by 242 percent, Guatemala by 369 percent, Iraq by 344 percent, Kenya by 284 percent, Liberia by 300 percent, Malawi by 741 percent, Mali by 408 percent, Niger by 766 percent, Somalia by 663 percent, Uganda by 396 percent, Yemen by 299 percent. Even the United States is projected to grow by 53 percent by 2100, from 315 million in 2012 to 478 million. I do just want to point out that if the current global rate of reproduction continues, by the end of this century there will not be ten billion of us. There will be twenty-eight billion of us."

"If we discovered tomorrow that there was an asteroid on a collision course with Earth, and—because physics is a fairly simple science—we were able to calculate that it was going to hit Earth on June 3, 2072, and we knew that its impact was going to wipe out 70 percent of all life on Earth, governments worldwide would marshal the entire planet into unprecedented action. Every scientist, engineer, university, and business would be enlisted: half to find a way of stopping it, the other half to find a way for our species to survive and rebuild if the first option were unsuccessful. We are in almost precisely that situation now, except that there isn’t a specific date and there isn’t an asteroid. The problem is us. Why we are not doing more about the situation we’re in—given the scale of the problem and the urgency—I simply cannot understand. We’re spending 8 billion euros (about 11 billion dollars [at the writing's current exchange]) at to discover evidence of a particle called the Higgs-Boson, which may or may not eventually explain the concept of mass and provide a partial thumbs-up for the “standard model” of particle physics. And CERN’s physicists are keen to tell us it is the biggest, most important experiment on Earth. It isn’t. The biggest and most important experiment on Earth is the one we're all conducting, right now, on Earth itself. Only an idiot would deny that there is a limit to how many people our Earth can support. The question is, is it seven billion (our current population), 10 billion or 28 billion? I think we've already gone past it. Well past it. We could change the situation we are now in. Probably not by technologizing our way out of it, but by radically changing our behavior. But there is no sign that this is happening, or about to happen. I think it’s going to be business as usual for us."

"Whether or not such a hypothesis fully accounts for the population increase that accompanies a sedentary life, there can be no doubt that human numbers soared. In the interval from 10,000 to 6000 years ago—a mere 160 human generations—the population of the Near East is estimated to have increased from less than 100,000 people to more than three million. With each increase, additional pressure was placed upon the food producers to domesticate new species and to invent new technologies, such as those based on the plow and on irrigation. Human beings now found themselves on a treadmill from which to this day they have not been able to get off. They are still plagued by the basic paradox of food production: Intensification of production to feed an increased population leads to a still greater increase in population."

"During the brief time since James Watt's commercial production of the improved Newcomen steam engine in 1775, a revolution unparalleled in human history has occurred at all levels of society and has penetrated all aspects of culture. The technological innovations are, of course, dramatic, but equally important are the biological, political, social, and economic consequences of modernization. From a biological perspective, the most important consequence is the extension of the human life span and the growth in human numbers. In the past two centuries, life expectancy has nearly tripled and the population of our species has multiplied five times over."

"If left unchecked, populations (of any organism) tend to grow exponentially. But they never grow forever. Eventually resources are depleted and the population declines. When the population is again small enough that resources are plentiful, exponential growth resumes. The result is a boom-bust cycle — stability through fluctuation. Of course, if the fluctuations are huge, we can hardly call this ‘stability’. But in most healthy ecosystems, population fluctuations are small. The key to dampening boom-bust cycles appears to be diversity. When there are many species in an ecosystem, each keeps the population of others in check. Prolonged exponential growth never gets a foothold."

"Overpopulation is described as a societal problem, with the individual and collective behavior of people as a causal agent."

"What are [we] made of, fairy dust and happy thoughts? No, [we] are made of proteins — of food! Without a sufficient food supply, such a population cannot be achieved. We understand this as a basic biological fact for every other species on this planet, that population is a function of food supply. Yet we continue to believe that the magic of free will exempts us from such basic biological laws."

"When the First World rushes in with foreign aid, food, and humanitarian aid to a desert area in the midst of a famine, we serve to prop up an unsustainable population. That drives a population boom in an area that already cannot support its existing population. The result is a huge population dependent on outside intervention that itself cannot be indefinitely sustained. Eventually, that population will crash once outside help is no longer possible — and the years of aid will only make that crash even more severe. In the same way that the United States’ policy of putting out all forest fires in the 1980s led to an even worse situation in its forests, our benevolence and good intentions have paved the way to a Malthusian hell."

"The human race currently consumes some 40% of the earth’s photosynthetic capacity. This monopoly on the earth’s resources is having a devastating effect. We are seeing the extinction of some 140 species every day, some thousands of times higher than the normal background rate. Today, right now, we are seeing extinction rates unparalleled in the history of the earth. We are undeniably in the midst of the seventh mass extinction event in the history of the earth — the Holocene Extinction. Unlikely previous extinction events, however, this one is driven by a single species. This is the true danger of overpopulation, not our inability to feed a growing population. As much as we would deny it, we depend on the earth to live. Dwindling biodiversity threatens the very survival of our species. We are literally cutting the ground out from under our feet. Increasing food production only increases the population; our current attitudes about food security has locked us into what Daniel Quinn called a “Food Race,” by comparison to the Arms Race of the Cold War."

"Overpopulation is the root cause of all other environmental problems … [and] is the natural consequence of the Food Race — driven by the constant need to expand. That need is a systemic consequence of complex society. The alternative to overpopulation, then, is to reverse the trend of intensifying complexity and accept greater simplicity: in a word, collapse."

"The main driving force behind the Holocene Extinction is the twin forces of overpopulation and intensified agricultural production. As more land is converted into cultivated fields, we approach important tipping points in how much of the world’s photosynthetic capacity is tied up in a single species. Deforestation is driven primarily by the need to feed an ever-growing populaton, but also for that population’s other resource needs, such as lumbering and mining. That deforestation has been responsible for anthropogenic atmospheric change for thousands of years, but as the positive feedback loop of the Food Race reached new levels, we were forced to either adopt fossil fuels, or collapse. Those fuels have intensified our atmospheric impact to obscene levels, yielding a new crisis in global warming. We do not face a long laundry list of environmental problems: we face a single, multi-faceted crisis. That crisis is complex society itself. The problems we face are the direct consequence of the positive feedback loop of complex society, and the Food Race in particular."

"If nobody died the planet would soon run out of room for more people. How would this world be run (our political systems are far from perfect now); who would decide what type of house one lived in, what type of food one ate? What would we do for a living?"

"The study of population is not a very exact science. No one forecast the population collapse that is occurring in post-communist European Russia, or the scale of the fall in fertility that is under way [sic] in much of the world. The margin of error in calculations of fertility and life expectancy is large. Even so, a further large increase is inevitable. […] A human population of approaching 8 billion [sic] can be maintained only by desolating the Earth. If wild habitat is given over to human cultivation and habitation, if rainforests can be turned into green deserts, if genetic engineering enables ever-higher yields to be extorted from the thinning soils – then humans will have created for themselves a new geological era, the Eremozoic, the Era of Solitude, in which little remains on the Earth but themselves and the prosthetic environment that keeps them alive."

"The future is brutally simple to anticipate; all overshot species collapse, and we have – by [apparently] transcending time via the levering of fossil energy – levered our species’ overshoot more than any ever has (or, almost certainly, ever could)."

"Over the last century, billions have enjoyed better, fuller and more enriched lives than their ancestors could dream of—but when all the bills for that are paid who knows how the ledgers of the two enterprises will stand?"

"My growing environmental awareness only adds more fuel to the argument for having no children. And the logic of never-ending consumption does not just harm the environment, it kills people too."

"The skeleton of our primate ancestors developed for millions of years to support a creature that walked on all fours and had a relatively small head. Adjusting to an upright position was quite a challenge, especially when the scaffolding had to support an extra-large cranium. Humankind paid for its lofty vision and industrious hands with backaches and stiff necks. Women paid extra. An upright gait required narrower hips, constricting the birth canal - and this just when babies’ heads were getting bigger and bigger. Death in childbirth became a major hazard for human females. Women who gave birth earlier, when the infants brain and head were still relatively small and supple, fared better and lived to have more children. Natural selection consequently favoured earlier births. And, indeed, compared to other animals, humans are born prematurely, when many of their vital systems are still underdeveloped. A colt can trot shortly after birth; a kitten leaves its mother to forage on its own when it is just a few weeks old. Human babies are helpless, dependent for many years on their elders for sustenance, protection and education. This fact has contributed greatly both to humankind’s extraordinary social abilities and to its unique social problems. Lone mothers could hardly forage enough food for their offspring and themselves with needy children in tow. Raising children required constant help from other family members and neighbours. It takes a tribe to raise a human. Evolution thus favoured those capable of forming strong social ties. In addition, since humans are born underdeveloped, they can be educated and socialised to a far greater extent than any other animal. Most mammals emerge from the womb like glazed earthenware emerging from a kiln - any attempt at remoulding will scratch or break them. Humans emerge from the womb like molten glass from a furnace. They can be spun, stretched and shaped with a surprising degree of freedom. This is why today we can educate our children to become Christian or Buddhist, capitalist or socialist, warlike or peace-loving."

"Rather than heralding a new era of easy living, the Agricultural Revolution left farmers with lives generally more difficult and less satisfying than those of foragers. Hunter-gatherers spent their time in more stimulating and varied ways, and were less in danger of starvation and disease. The Agricultural Revolution certainly enlarged the sum total of food at the disposal of humankind, but the extra food did not translate into a better diet or more leisure. Rather, it translated into population explosions and pampered elites. The average farmer worked harder than the average forager, and got a worse diet in return. The Agricultural Revolution was history’s biggest fraud."

"The last 500 years have witnessed a phenomenal and unprecedented growth in human power. In the year 1500, there were about 500 million Homo sapiens in the entire world. Today, there are 7 billion. The total value of goods and services produced by humankind in the year 1500 is estimated at $250 billion, in today’s dollars. Nowadays the value of a year of human production is close to $60 trillion. In 1500, humanity consumed about 13 trillion calories of energy per day. Today, we consume 1,500 trillion calories a day. (Take a second look at those figures — human population has increased fourteenfold, production 240-fold, and energy consumption 115-fold.)"

"Since the Industrial Revolution, the world's human population has burgeoned as never before. In 1700 the world was home to some 700 million humans. In 1800 there were 950 million of us. By 1900, we almost doubled our numbers to 1.6 billion. And by 2000, that quadrupled to 6 billion. Today [as of this writing] there are just shy of 7 billion Homo Sapiens."

"Today [as of this writing], the earth's continents are home to almost 7 billion Sapiens. If you took all these people and put them on a large set of scales, their combined mass would be about 300 million tons. If you then took all our domesticated farmyard animals—cows, pigs, sheep, and chickens—and placed them on an even larger set of scales, their mass would amount to about 700 million tons. In contrast, the combined mass of all surviving large wild animals—from porcupines and penguins to elephants and whales—is less than 100 million tons. Our children’s books, our iconography, and our TV screens are still full of giraffes, wolves, and chimpanzees, but the real world has very few of them left. There are about 80,000 giraffes in the world, compared to 1.5 billion cattle; only 200,000 wolves, compared to 400 million domesticated dogs; only 250,000 chimpanzees—in contrast to billions of humans. Humankind really has taken over the world."

"Around 1990, we became the most numerous mammalian species on the planet, outnumbering even rats."

"All measures to thwart the degradation and destruction of our ecosystem will be useless if we do not cut population growth. By 2050, if we continue to reproduce at the current [but declining] rate, the planet will have between 8 billion and 10 billion people, according to a recent U.N. forecast. This is a 50 percent increase. And yet government-commissioned reviews, such as the Stern report in Britain, do not mention the word population. Books and documentaries that deal with the climate crisis, including Al Gore’s An Inconvenient Truth, fail to discuss the danger of population growth. This omission is odd, given that a doubling in population, even if we cut back on the use of fossil fuels, shut down all our coal-burning power plants and build seas of wind turbines, will plunge us into an age of extinction and desolation unseen since the end of the Mesozoic era, 65 million years ago, when the dinosaurs disappeared."

"We are experiencing an accelerated obliteration of the planet’s life forms — an estimated 8,760 species die off per year — because, simply put, there are too many people. Most of these extinctions are the direct result of the expanding need for energy, housing, food, and other resources. The Yangtze River dolphin, Atlantic gray whale, West African black rhino, Merriam's elk, California grizzly bear, silver trout, blue pike, dusky seaside sparrow are all victims of human overpopulation. Population growth, as E. O. Wilson says, is "the monster on the land." Species are vanishing at a rate of a hundred to a thousand times faster than they did before the arrival of humans. If the current rate of extinction continues, Homo sapiens will be one of the few life forms left on the planet, its members scrambling violently among themselves for water, food, fossil fuels, and perhaps air until they too disappear. Humanity, Wilson says, is leaving the Cenozoic, the age of mammals, and entering the Eremozoic — the era of solitude. As long as the Earth is viewed as the personal property of the human race, a belief embraced by everyone from born-again Christians to Marxists to free-market economists, we are destined to soon inhabit a biological wasteland."

"A world where 8 billion to 10 billion people are competing for diminishing resources will not be peaceful. The industrialized nations will, as we have done in Iraq, turn to their militaries to ensure a steady supply of fossil fuels, minerals and other nonrenewable resources in the vain effort to sustain a lifestyle that will, in the end, be unsustainable. The collapse of industrial farming, which is made possible only with cheap oil, will lead to an increase in famine, disease and starvation. And the reaction of those on the bottom will be the low-tech tactic of terrorism and war. Perhaps the chaos and bloodshed will be so massive that overpopulation will be solved through violence, but this is hardly a comfort."

"Our core ecological problem is not climate change. It is overshoot, of which global warming is a symptom. Overshoot is a systemic issue. Over the past century-and-a-half, enormous amounts of cheap energy from fossil fuels enabled the rapid growth of resource extraction, manufacturing, and consumption; and these in turn led to population increase, pollution, and loss of natural habitat and hence biodiversity. The human system expanded dramatically, overshooting Earth’s long-term carrying capacity for humans while upsetting the ecological systems we depend on for our survival. Until we understand and address this systemic imbalance, symptomatic treatment (doing what we can to reverse pollution dilemmas like climate change, trying to save threatened species, and hoping to feed a burgeoning population with genetically modified crops) will constitute an endlessly frustrating round of stopgap measures that are ultimately destined to fail."

"During the last 200 years, per capita energy usage grew eight-fold, while human population expanded at about the same rate. As a result of energy growth, all the things we do with energy became more doable. Transportation, manufacturing, agriculture, and mining exploded in scale. Energy became so abundant that it seemed we could solve any human problem, now or in the future, just by throwing more energy at it. We even reconfigured our economic system so that it assumes and requires perpetual growth. But growth in fossil-fuel energy can’t continue much longer: depletion and climate change will see to that. And even if we make a wholehearted effort to switch to low-carbon energy sources, we face limits to nature’s supplies of materials with which to make solar panels, wind turbines, nuclear reactors, and batteries. The ways we’re currently trying to share and manage power are insufficient also because we have failed to understand power itself. Rather than accepting that power limits exist, then surveying them and adapting ourselves to them, we try to finesse or deny them. We respond to climate change by hoping for a renewable energy transition—without questioning the amounts of energy we use or what we do with it. We deal with economic inequality by establishing minimal safeguards for the poor—without examining the structural means by which some people enrich themselves to absurd degrees."

"Prior to the widespread use of coal, oil, and natural gas, agrarian societies saw cyclical periods of rise and fall. But the scale of expansion since the dawn of the fossil-fueled industrial revolution, beginning roughly at the start of the 19th century, has been unprecedented. Energy usage per capita has grown 800 percent, as has population. Meanwhile, the contours of society have been transformed: for the first time in human history, most people now live in cities."

"Fossil fuels enabled a dramatic expansion of energy usable by humanity, in turn enabling unprecedented growth in human population, economic activity, and material consumption."

"Global human population has doubled three times in the past 200 years, surging from 1 billion in 1820 to 2 billion in 1927, to 4 billion in 1974, to 8 billion today. Its highest rate of growth was in the 1960s, at over 2 percent per year; that rate is now down to 1.1 percent. If growth continues at the current rate, we’ll have about 18 billion people on Earth by the end of this century. All of this would be fine if we lived on a planet that was itself expanding, doubling its available quantities of minerals, forests, fisheries, and soil every quarter-century, and doubling its ability to absorb industrial wastes. But we don’t. It is essentially the same beautiful but finite planet that was spinning through space long before the origin of humans."

"Agriculture enabled population growth and social complexity, but it gradually robbed soils of nutrients. Sailing ships guided with clocks and navigational charts could increase the scope of trade, but building wooden ships (and making charcoal for forging steel) was leading to the deforestation of whole continents. A reckoning with limits seemed to be in store. Then a miracle happened. People who lived in some key centers of global trade started using fossil fuels—energy sources capable of delivering power in previously unimaginable and seemingly endless quantities. Coal, oil, and natural gas enabled the development of transport technologies (steamships, railroads, cars, trucks, and airplanes) that overcame prior limits to the speed of travel and trade, so that products and resources that were abundant in one place could be transported to places where they were scarce. Fossil fuels could be used to increase the rates of resource extraction via powered mining machinery, and to process lower grades of ores as more concentrated ores were depleted. They could be fashioned into plastics and chemicals to substitute for some natural materials that were getting scarce, such as hardwoods and whale oil. And they could be made into artificial fertilizers, which could replace soil nutrients lost due to unsustainable agricultural practices. All these developments together enabled population growth at rates that far outstripped historic trends: human numbers expanded from one billion to eight billion in a mere two centuries. We were, in effect, stretching existing constraints on population and consumption to the point that it was difficult for many people to see that boundaries still existed at all."

"As we’ve grown our population and our per capita consumption rates, we’ve been taking habitat away from other organisms. As a result, nature is in full retreat. Vertebrate and invertebrate animal species have suffered average population declines of 70 percent in the past 50 years, and thousands of plant species are endangered as well."

"For a population of field mice in overshoot, the critical resource might consist of small plants whose unusually robust growth has been triggered by high levels of rainfall. For humanity currently, the critical resource is fossil energy. Temporary energy abundance has led to many good things (for some of us, anyway): more food, more people, more commercial products, more knowledge, more comfort, and more convenience. But we are about to become victims of our own success."

"It’s sad when loved ones die, and few of us look forward to our own demise; hence the perennial quest for an elixir of eternal life, or at least a cure for cancer. But if nobody died, the planet would quickly fill with humans and empty of all the things that feed and provision us. Death clears space for new life; it is the non-negotiable price of admission to the great banquet of existence."

"The past few thousand years of human history have already seen several critical accelerators. The creation of the first monetary systems roughly 5,000 years ago enabled a rapid expansion of trade that ultimately culminated in our globalized financial system. Metal weapons made warfare deadlier, leading to the takeover of less-well-armed human societies by kingdoms and empires with metallurgy. Communication tools (including writing, the alphabet, the printing press, radio, television, the internet, and social media) amplified the power of some people to influence the minds of others. And, in the past century or two, the adoption of fossil fuels facilitated resource extraction, manufacturing, food production, and transportation, enabling rapid economic expansion and population growth. Of those four past accelerators, our adoption of fossil fuels was the most potent and problematic. In just two centuries, energy usage per capita has increased eightfold, as has the size of the human population. The period since 1950, which has seen a dramatic increase in the global reliance on petroleum, has also seen the fastest economic and population growth in all of human history. Indeed, historians call it the “Great Acceleration.” Neoliberal economists hail the Great Acceleration as a success story, but its bills are just starting to come due. Industrial agriculture is destroying Earth’s topsoil at a rate of tens of billions of tons per year. Wild nature is in retreat, with animal species having lost, on average, 70 percent of their numbers in the past half-century. And we’re altering the planetary climate in ways that will have catastrophic repercussions for future generations. It’s hard to avoid the conclusion that the whole human enterprise has grown too big, and that it is turning nature (“resources”) into waste and pollution far too quickly to sustain itself. The evidence suggests we need to slow down, and, in some cases at least, reverse course by reducing population, consumption, and waste."

"Depleting and climate-changing coal, oil, and natural gas have brought about dramatic human population growth, along with immense profits and unprecedented wealth (for the few). But all of these presumed and probably transitory benefits have been based on depleting natural resources, and on processes that are perilously changing the climate and degrading ecosystems across the planet. Every time we pick up a gasoline-powered machine we are viscerally linked to that chain of ersatz benefits and spiraling impacts."

"Of course, we also have to think about the role of population going forward. The more the global population grows, the more difficult this challenge will be. As we approach this question, it's crucial—as always—that we focus on underlying structural drivers. Many women around the world do not have control over their bodies and the number of children they have. Even in liberal nations, women come under heavy social pressure to reproduce, often to the point where those who choose to have fewer or no children are interrogated and stigmatised. Poverty exacerbates these problems... And of course capitalism itself creates pressures for population growth: more people means more labour, cheaper labour, and more consumers. These pressures filter into our culture, and even into national policy: countries like France and Japan are offering incentives to get women to have more children, to keep their economies growing."

"No one lives within a day’s walk of a coal mine, an iron ore source, and a smelter that can operate without a source of electricity, plus food. The old smelters didn’t use electricity to drive the huge motors moving heavy hot metal and slag around. The first smelters were close to coal and iron ore sources, but we used them up; they no longer exist close to each other. In the year 1500, we had a world population of around 450 million and grew massively over the next 250 years to the start of the industrial revolution by increasingly using the resources of the ‘new world’. We’ve been on an upward trajectory ever since, especially since around 1800 when fossil energy came into use. People just don’t understand our extreme (and still growing) overpopulation problem given the imminent decline of oil, and especially diesel. Assuming “we’ll downsize this” or “relocalize that” ignores the fact that once oil supply shifts to contraction, the declines will be permanent year after year, and with diesel shortages the ability to build anything new all but disappears. It will be a sad sight with suffering everywhere and increasing year after year. Survivors will have to be hard people, protecting and providing for their own, at the exclusion of others. Everyone should look around their home and imagine it without the oil used to produce and deliver everything in it, because that’s the world of the future, with old decaying cold buildings and no food in cities."

"Using all available resources to expand its population is what every species that’s ever existed has always done until some limit is reached. Consider a mouse plague, enabled by human agricultural practices, with its huge population until the next frost or the grain is eaten, then a massive die-off in a short time."

"We have over 8 billion humans on the planet, and 99.99% of them have no idea modernity is going to end abruptly, and when it does so will destroy the plans of the [few who] did see it coming and tried to prepare in some way."

"One might think Humanity’s success is guaranteed, except for a few things: First, the increasing scarcity of oil, coal, and natural gas suddenly threatens to remove the punch bowl from which Humanity has been feeding. Second, the carrying capacity of the Earth is far less than 8 billion humans unless we continue to supplement with increasingly scarce resources. And, last, our centuries-long party has now broken the Earth in ways Humanity cannot repair."

"Is the proxy war in Ukraine turning out to be only a lead-up to something larger, involving world famine and a foreign-exchange crisis for food- and oil-deficit countries? U.S. Cold War strategy is not alone in thinking how to benefit from provoking a famine, oil and balance-of-payments crisis. Klaus Schwab’s World Economic Forum worries that the world is overpopulated—at least with the “wrong kind” of people. As Microsoft philanthropist... Bill Gates has explained: “Population growth in Africa is a challenge.” His lobbying foundation’s 2018 “Goalkeepers” report warned: “According to U.N. data, Africa is expected to account for more than half of the world’s population growth between 2015 and 2050. Its population is projected to double by 2050,” with “more than 40 percent of world’s extremely poor people... in just two countries: Democratic Republic of the Congo and Nigeria.” Gates advocates cutting this projected population increase by 30 percent by improving access to birth control and expanding education to “enable more girls and women to stay in school longer, have children later.” But how can that be afforded with this summer’s looming food and oil squeeze on government budgets?"

"Perhaps the most ambiguous of these [technological] achievements [of the industrial age] is the one that began in mid-nineteenth century with improvements in public health, vaccinations, and antibiotics. These methods of death control emerged too rapidly to be offset by methods of birth control and populations exploded. Again, who can speak against this from within the old paradigm? In fact, it is only from the newer ecological paradigm that we are able to recognize that all this marvelous technology has... likely led the human population to overshoot the carrying capacity of the earth. Even from this perspective many of us would... want to save lives now in hopes that somehow there will be enough resources for those who come after us. In less complex animal populations, an overshoot leads to a crash, or die-off. Can humans somehow circumvent this conclusion without relying on further damaging drawdown strategies? … a basic change in our technologies, and acceptance of a steady state in economics reinforced by a compatible spiritual orientation, may at least mitigate human suffering and loss."

"Unlike plagues of the dark ages or contemporary diseases we do not yet understand, the modern plague of overpopulation is soluble by means we have discovered and with resources we possess. What is lacking is not sufficient knowledge of the solution but universal consciousness of the gravity of the problem and education of the billions who are its victims."

"We have learned a lot in the 50 years since "" was published. We should not shy away from discussing what actions are ethically permissible to facilitate a stable level of population growth, nor should we leave this discussion in the hands of the affluent. The conversation about ethics, population, and reproduction needs to shift from the perspective of white donor countries to the places and people most affected by poverty, climate change and environmental degradation."

"All we can say now is, that, even now, 600 persons could easily live on a square mile; and that … 1,000 human beings—not idlers—living on 1,000 acres could easily, without … overwork, obtain … a luxurious vegetable and animal food, as well as the flax, wool, silk and hides necessary for their clothing. As to what may be obtained under still more perfect methods—also known but not yet tested on a large scale—is better to abstain from any forecast: so unexpected are the recent achievements of intensive culture. We thus see that the over-population fallacy does not stand the very first attempt at submitting it to a closer examination."

"It has been estimated that the world human population stood at about one billion around the early 1800s, which was roughly about when the industrial adventure began to gain traction. It has been inferred from this that a billion people is about the limit that the planet Earth can support when it is run on a nonindustrial basis. World population is now past six and a half billion, having more than doubled since my childhood in the 1950s. The mid-twentieth century was a time of rising anxiety over the “population explosion.” The marvelous technological victory over food shortages, including the “green revolution” in crop yields, accelerated that already robust leap in world population that had begun with modernity. Dramatic improvements in sanitation and medicine extended lives. Industry sopped up expanding populations and reassigned them from rural lands to work in the burgeoning cities. The perceived ability of the world to accommodate these newcomers and latecomers in a wholly new disposition of social and economic arrangements seemed [to] be the final nail in the coffin of Thomas Robert Malthus…"

"Malthus was certainly correct [that demand will outstrip supply], but... [hydrocarbons] ...skewed the [supply-demand] equation over the past [two] hundred years while the human race has enjoyed an unprecedented orgy of [a fraction of] nonrenewable condensed solar energy accumulated over eons of prehistory. The “green revolution” in boosting crop yields was minimally about scientific innovation in crop genetics and mostly about dumping massive amounts of fertilizers and pesticides made... of ...[petroleum] onto crops, as well as employing irrigation at a fantastic scale made possible by abundant oil and gas. The cheap oil age created an artificial bubble of plen[t]itude for a period not much longer than a human lifetime, a hundred years. Within that comfortable bubble, the idea took hold that only grouches, spoilsports, and godless maniacs considered population hypergrowth a problem [with a direct solution], and that to even raise the issue was indecent. ...As oil ceases to be cheap and the world reserves arc toward depletion, we will indeed suddenly be left with an enormous surplus population... that the ecology of the earth will not support. No political program of birth control will avail. The people are already here. The journey back to non-oil population homeostasis will not be pretty. We will discover the hard way that population hypergrowth was simply a side effect of the oil age. It was [more of] a condition [without a remedy], not a problem with a [direct] solution. That is what happened, and we are stuck with it."

"Cheap oil had allowed populations to explode in precisely those parts of the world that had had, for millennia, a high infant mortality rate and modest life expectancy. Cheap oil was behind the "green revolution" that increased the food supply in the nonindustrial world. Oil was also behind many of the medicines and preventives that had neutralized… diseases. Now, suddenly, most of those children… survived, grew up, and produced more children who survived and grew up, and over… the twentieth century, the global populations hurtled into extreme numerical overshoot. Populations were, in effect, eating oil, notably in [the form of] food exports from the United States, where agribusiness had completely taken over from agriculture. Local farmers in Africa, Asia, or South America couldn’t compete with corporate Archer Daniels Midland’s oil-and-gas-based grain crops and U.S. government subsidies."

"Peak human population will surely lag … peak oil and peak mineral resources until these conditions express themselves as food shortages. This means that the human population will continue to rise for a while, even as we begin to encounter these … strict resource limits. It’s not possible to estimate how much the population will increase because the relationship between energy and mineral resources and food production is a very fragile equation, subject to any number of discontinuities. To these, add the complications of weather disasters arising from climate change, including drought, the spread of plant diseases, and so forth. This lagging further rise in [the] human population will only make the inevitable contraction more acute once food shortages begin. [Overpopulation] amounts to a human population overshoot … to the planet Earth’s ecology. We're putting a strain on everything the earth has to offer us. While the combination of peak stuff and [too many] billion humans is forcing the issue, ...the truth is that circumstances will now determine what happens, not policies or personalities. … Population overshoot is therefore unlikely to yield to management. Rather, the usual suspects will enter the scene and do their thing: starvation, disease, … violence … [and] death."

"Fossil fuels’ biggest impact on the agricultural sector stems from the use of natural gas in industrial fertilizer production. Industrial fertilizer was first mass-produced in 1914 using what came to be known as the . This invention enabled the , a boom in agricultural production that took place in the latter half of the 20th century, starting in Mexico and India. From 1961 to 2010, cereal yields per acre increased by 217 percent in Mexico and 183 percent in India. It is no coincidence that the human population has more than quadrupled since 1920. We often attribute the Green Revolution to the spread of high-yielding crop varieties. Yet these varieties typically require industrial fertilizer application. The Haber-Bosch method, combined with mechanization and pesticides derived from fossil fuels, [has] represented a massive and unsustainable injection of fossil fuels into our food system. Today, the production of one food calorie in the United States requires 2.7 fossil fuel calories."

"Driven by the Anthropocene engine, human population has grown exponentially, and individual societies have approached collapse multiple times over the past 8,000 years. The disappearance of the Easter Island civilization and the collapse of the Mayan empire, for example, have been linked to the depletion of environmental resources as populations rose. The dramatic decline of the European population during the Black Death in the 1300s was a direct consequence of crowded and unsanitary living conditions that facilitated the spread of Yersenia pestis, or plague."

"In the 20th century we decisively broke our dependence on energy systems that were fed by the wind and sun and which we supplemented with human and animal muscle power. That leap was made possible by innovations that allowed us to extract, pump, use, and transform raw materials, particularly to unlock energy stored in coal and oil to make chemicals and plastics. That in turn allowed a massive expansion in population, lifespans, and economic growth. The rise of industrial capitalism from 1851 to 1971 went hand in hand with a surge in population, mainly in cities, provided with better food and public health."

"On a global level, there is no threat to human survival greater than that posed by world overpopulation—paradoxical though that may seem—and it is abundantly clear that consensus decision making is ineffective for dealing with that. Some kind of “solution” is nonetheless unavoidable, and is certain to be ugly. To say that there is no visible world leadership on that transcendental question is to understate the case. Optimists on the population problem don’t measure progress in terms of a decrease in population, or even a decrease in the rate of increase, but in terms of a decrease in the rate of increase of the rate of increase."

"The human population will continue to increase until it can’t. When it can no longer increase, it will crash. Our extreme efforts to focus our minds elsewhere are symptoms of a desperate attempt to find solid footing, to believe in a future that will not vanish. Mankind has had a storied existence on Earth. Our thirst for knowledge and innovation has provided comfort and security. However, it is becoming increasingly evident that our remarkable progress has become our worst enemy. We know our planet is finite. Images of Earth from space make it plain for all to see. However, people routinely ignore this verifiable certainty in all aspects of their lives, treating the world as [if it were] infinite. Modern-day human activities are not only wiping out ecosystems and biodiversity but [also] plundering the clean air, water, and topsoil that helped bring about our tenure on the planet. Entire ecosystems have vanished, including the tallgrass prairie in North America, Madagascar’s rainforests, and the Aral Sea in Asia. We use Earth’s natural resources like a bunch of drunks on the greatest bender of all time. Human consumption is negatively modifying the planet and permanently damaging the biological systems upon which our continued existence depends. The deterioration of our ecosphere has been exponentially accelerating for at least 100,000 years. As technological advances improve our lives, humanity becomes increasingly detached from its environment and the natural resources allowing us to persist. People now have a much closer affinity with iPhones, Amazon, online shopping, restaurants and bars, Netflix, beauty salons, and sporting events than forests, grasslands, marshes, and oceans. Few now understand our existence on Earth is entirely dependent upon photosynthesis. Instead, they believe their survival is contingent on parents, doctors, farmers, governments, bankers, police, and other players in society. It’s not that those institutions, people, and specialties aren’t important, but they represent the retailers. Photosynthesis is the wholesaler. There is a supply chain disruption occurring on a massive scale in our relationship with the planet. The ancient forests and grasslands that provided the planet with free oxygen in the air and sequestered carbon dioxide, making it habitable for humans and other complex life, are nearly gone. For most people, the natural resources that support their existence and lifestyle might as well be from a distant galaxy. This extreme disconnect has resulted in people losing their capacity to understand the dire circumstances facing complex organisms on Earth, including themselves. The deafening alarm bells portending our extinction are routinely misunderstood or ignored. For those who perceive our state of crisis, there is a great deal of angst. Much of the frustration, anger, and sadness results from having unrealistic expectations of human beings. Despite our advanced technologies, the basic tenets of human behavior haven’t changed for centuries or millennia. Letting go of the false expectations that Homo sapiens can or will modify our behavior can bring us an element of peace. Expectations are incredibly powerful in structuring our moods and emotions. Identifying unrealistic expectations can reduce our chances of being disappointed and can increase happiness. A better understanding of our behavioral history can provide valuable insights into recognizing human capabilities and limitations."

"… as our population has grown, humans have been liquidating the planet’s natural resources for thousands of years. The effects of our current population on forests, grasslands, biodiversity, clean air, and water are catastrophic. Zero population growth means the planet would still be trying to support the current population, over 8 billion people. Humanity can no longer pay even the interest. We’ve already spent much of the planet’s clean air, water, and biodiversity with no mechanism for repayment. Zero population growth isn’t going to happen. We can’t curb our evolutionarily programmed need to grow and reproduce any more than we can stop the sun from rising. Like all populations of organisms on the planet, the number of humans will continue to increase until it’s no longer possible. When that day happens, Earth will be a truly inhospitable place."

"In 1968, with the release of their book The Population Bomb, Paul and Anne Ehrlich were among the first to identify the most significant factor that will precipitate the collapse of humanity. Their book inspired an environmentalist fad in the 1970s. The premise for the book was gradually rationalized away by most as the work of lunatics. It was listed by the Intercollegiate Review as one of the 50 worst books of the 20th century. In the Human Events list of the “Ten Most Harmful Books of the Nineteenth and Twentieth Centuries,” it garnered an 11th-place honorable mention. Since that time, the global population has more than doubled. During those five decades, humanity has identified six types of quarks, developed the modern internet, eradicated smallpox, decoded the human genome, and developed vaccines for Ebola and COVID-19. Despite all our new technologies and discoveries, the most basic concept of rapid human growth inside a finite system—our planet—leading to collapse is a concept too difficult for our greatest minds to reconcile. Humanity’s carefully calibrated psychological filters go into overdrive to prevent this simple mathematical postulate from entering our psyche. As seemingly prescient as the Ehrlichs were, our collision course with extinction was preordained long before their book was published in 1968."

"Population growth vanished from the agendas of mainstream environmental organizations that previously regarded escalating numbers as a major environmental threat. These groups were primarily shackled by their fear of alienating donors, ultimately selling their purpose and integrity for money. Criticism from progressive and conservative interests claiming that overpopulation is a myth further incentivized these groups to pretend the rising global population wasn’t a factor in planetary degradation."

"Those who defend the belief that overpopulation isn’t at the core of every environmental problem are not unique. Every myth presents itself as an authoritative, factual account, no matter how much the topic varies from natural law or ordinary experience. There is a long, bloody history of Homo sapiens defending myths against those who might either question their veracity or have a competing myth. It has resulted in the deaths of millions of people [and other animals] since the dawn of the Agricultural Revolution. As a result of ignoring the obvious reality, newborns are effectively positioned as moneymaking machines. The former prime minister of Japan suggested that women who bore no children should be barred from receiving pensions. In most countries, those who choose not to have children are required to pay for those who do through taxes. In this campaign for more babies, childbearing is reduced to a means for economic growth. Even though overpopulation, natural resource extraction, and environmental degradation are clearly linked, the needs of the economic market trump the needs of the planet. Children are nothing more than moneymakers in the eyes of politicians, forever blind to the moral, environmental, or humanitarian consequences of their policies. Market thinking has obliterated moral thinking on a grand scale. After all, if the West doesn’t produce more children, it can’t produce the wealth needed to look after parents when they retire. No social animal is ever guided by the interests of the entire species to which it belongs. No pika cares about the interests of the pika species; no northern spotted owl will lift a feather for the global northern spotted owl community; no wolf alpha male makes a bid for becoming the king of all wolves. Likewise, few humans care about the interests of Homo sapiens. People only care about themselves and those who directly affect their lives."

"Humanity has moved past the point where future generations are an issue. If there are any, they will be few in number. Ignoring the inevitable is something all species do. Humans are no different than bacteria in a Petri dish or a mountain pine beetle in a climate-stressed lodgepole pine forest. All available resources are utilized to grow and reproduce until the inevitable collapse. We’re traveling down the same path as all species that have gone through exponential increases. The only difference is Homo sapiens is doing it on a grander scale. The Herculean ability to ignore the greatest threat to our existence would be comical if not for the rapidly approaching consequential conclusion to our existence."

"Economic and political instability will continue to increase as food and water supplies are impacted in more areas on the planet by pollution, drought, flooding, and other extreme weather events. However, while the focus is almost entirely on the supply side of the economic equation, the demand side may be the bigger issue. The planet is currently adding an additional 80 million mouths to feed each year, 4.5 times more people than the entire population of Syria. As the chasm between uncertain supplies and increasing demand widens, the social and biological implications for humanity are both unpredictable and alarming."

"Many people, including environmentalists, often avoid linking the multitude of environmental problems to overpopulation. Some believe that a global shift to veganism could support the current population and more. Others attribute the crisis to various factors [that] are frequently cited as primary contributors to the ongoing environmental crisis, overshadowing the impact of population growth."

"[There's an] excessive number of humans who [want to] live a lifestyle that promotes equality, along with [others] being minimalist and/or vegan... [and] similar overpopulation by other organisms is considered a plague."

"Our emphasis [on] science has resulted in alarming rises in world populations that demand an ever-increasing emphasis [on] science to improve their standards and maintain their vigor."

"It is still the case that the worst enemies of life are, on the one hand, an excess of life (human life, in particular) and, on the other, the legislation and structure of societies based on . The sturdier a society, the more peaceful it is; the more efficient (i.e., the ransacking of natural resources), the quicker . Everything that upsets the established order of society, causing chaos and panic, gives time to nature and, ultimately, humans too."

"Population, when unchecked, increases in a geometrical ratio, Subsistence, increases only in an arithmetical ratio."

"The power of population is so superior to the power in the earth to produce subsistence for man, that premature death must in some shape or other visit the human race."

"What has caused the recent super-exponential rise in world population? Before the industrial revolution both fertility and mortality were comparatively high and irregular. The birth rate generally exceeded the death rate only slightly, and population grew exponentially, but at a very slow and uneven rate. In 1650 the average lifetime of most populations in the world was only about 30 years. Since then, [hu]mankind has developed many practices that have had profound effects on the population growth system, especially on mortality rates. With the spread of modern medicine, public health techniques, and new methods of growing and distributing foods, death rates have fallen around the world. […] On a world average the gain around the positive feedback loop (fertility) has decreased only slightly while the gain around the negative feedback loop (mortality) is decreasing. The result is an increasing dominance of the positive feedback loop and the sharp exponential rise in population […]."

"H. sapiens took around 250,000 years to reach a global population of 1 billion in 1820, and just over 200 years to go from 1 billion to 8 billion. This was largely made possible by our species’ access to cheap, easy, exosomatic energy, mainly fossil fuels. Fossil fuels enabled us to reduce negative feedback (e.g. food shortages) and thus delay and evade the consequences of surpassing natural limits. In that same 200 year period, fossil energy (FF) use increased 1300-fold, fueling a 100-fold increase in real gross world product, i.e. consumption, and the human enterprise is still expanding exponentially."

"There is no way we could keep going as we have been. The increase in human population in the 1990s has exceeded the total population in 1600. The population has grown more since 1950 than it did during the previous four million years. The reasons for our recent rapid growth are pretty clear. Although the Industrial Revolution speeded historical growth rates considerably, it was really the public health revolution, and its spread to the Third World at the end of the Second World War, that set us galloping. Vaccines and antibiotics came all at once, and right behind came population. In Sri Lanka in the late 1940s life expectancy was rising at least a year every twelve months. How much difference did this make? Consider the United States: if people died throughout this century at the same rate as they did at its beginning, America's population would be 140 million, not 270 million."

"The Earth's population is plagued by famines, energy shortages, epidemics, environmental pollution, degeneration, terrorism, dictatorship, anarchism, slavery, excessive increase of waste materials, racial hatred, food shortages, destruction of rain forests, the "greenhouse effect", pollution of lakes, streams and oceans, hatred towards asylum-seekers; radioactive emissions, chemical pollution of water, air, plants, food, human beings and animals. Crime, murder, mass murders, manslaughter; alcoholism, hatred of strangers, oppression, hatred of one's fellowman, extremism, sectarianism, drug addiction, overpopulation, annihilation of animal species, war, violence, torture and capital punishment, general mismanagement, water contamination, eradication of plant species; hatred, vice, jealousy, lovelessness, lack of logic, false humanitarianism, lack of housing, increased traffic, destruction of arable land, unemployment, the collapse of health care, the collapse of care for the elderly, destruction of nature, the collapse of solid waste removal, and the lack of living space, among others. In spite of the many efforts, mankind's problems are not decreasing but, instead, continue to rise steadily in direct proportion to population increases."

"… technology use harnesses far more energy and materials than we could ever manage without it, and while doing so may make our lives much easier and more comfortable, it comes at the cost of increasing ecological overshoot. As we increase overshoot, we concomitantly increase all the symptom predicaments that overshoot causes. Technology use also has another nasty side effect. It reduces and/or eliminates negative feedbacks which once kept our numbers in check. Many diseases we once suffered from like smallpox, measles, whooping cough, tetanus, etc. have been temporarily eliminated by the technological development of vaccines. Our medical industry has also wiped out many other diseases through proper sanitation, use of antiseptics, anesthetics (allowing surgeries to correct most internal ailments), antibiotics, antifungals, and antivirals to kill or prevent many diseases, and many other innovations that allow us to live better, more comfortable lives. The development of indoor plumbing, electrical systems, heating and air conditioning systems, insulation, refrigerators and freezers, and cooking devices all allow us to accomplish daily tasks either much easier or provide more comfort to us by regulating temperature and humidity levels in our living spaces. Therefore, technology use reduces or removes negative feedback thereby promoting population growth which also promotes technology growth. However, in terms of reducing overshoot (and symptom predicaments such as climate change, energy and resource decline, pollution loading, and biodiversity decline), technology use is maladaptive. This will become painfully clear as time moves forward when more or different technology does not actually solve overshoot. Population decline is what will actually work to reduce overshoot, caused by the failure of our agricultural systems, increased disease caused by antimicrobial resistance and new viruses emerging, and increased failures of infrastructural systems caused by extreme weather events. Reduced technology use will be facilitated by this mechanism, and ALL species wind up experiencing die-off whether they use technology or not."

"Most non-domesticated life on earth is in decline and about 200 species a day are going extinct due to a wide range of environmental problems. Many humans are at risk of being harmed or killed by related problems this century. All of the many problems are caused by the same thing: humans have used non-renewable energy to explode their population from 1 billion to 7 billion in 100 years, and now consume so large a share of the earth’s resources that almost all non-domesticated species are in decline."

"We’re in serious trouble. Many red lights are flashing on the dashboard. Most people are now aware that something is seriously wrong, and each has their favorite lens through which to view the problems… The common denominator to all of these problems is overshoot. Very few people are able to see through the lens of overshoot because overshoot is a very unpleasant topic with no painless solutions and no way to avoid its consequences, and because humans evolved to deny unpleasant realities like overshoot."

"Human numbers are rising at roughly 1.2% a year, while numbers are rising at around 2.4% a year. By 2050 the world’s living systems will have to support about 120m tonnes of extra humans and 400m tonnes of extra farm animals."

"Baconian science is at the root of the apocalypse. We have been blessed by advances in medicine, agriculture and engineering. Science has done exactly what we asked of it and now we are set for annihilation. If European science had petered out after the discoveries of the seventeenth century, we would be less numerous and [the] Earth would not be warming."

"This moment is special because we have dramatically built up our population, technology, science, medicine, and democratic institutions as a direct result of vast amounts of surplus energy stemming from a one-time resource. The fossil fuel experience has made us dangerously confident about our cleverness and dominance over nature. What makes this century special, then, is that we will have to cope with a diminishing supply rate of the resource that has been of paramount importance to our high-tech existence."

"Humans collectively must ultimately face the uncomfortable question of whether Earth’s natural systems can support 8 billion or more people at a modern standard of living. Since the resource footprint of a U.S. citizen is at least four times that of the global average, the key question is whether the planet can support an increase in material throughput four times higher than present when the strain is apparent already. As noble as it may be to wish [for] a modern living standard for an eventual ten billion or more people, it is likely that committing to such a course could result in more human suffering than would transpire under the adoption of more modest goals. The responsible path is to reduce global resource dependencies and abandon the imperative for growth starting now."

"Even something as seemingly altruistic as health care selfishly focuses on human health, to the exclusion and often direct detriment of ecosystem health. Are we really doing ourselves favors in the long term by making the destructive human enterprise healthier, more populous, longer-living, and therefore better able to carry out its damaging activities? If this sounds abhorrently anti-human, it’s because the human enterprise is currently relentlessly anti-planet. Anything that is anti-planet will dismantle ecosystems that serve as critical life support for humans, spelling failure for the human enterprise. So it’s really the human enterprise that is anti-human by way of being anti-planet. […] The best way to assure long-term prosperity is to forge a non-human-centric partnership with nature that does not always put short-term human interests above those of non-human elements of nature. Even “good” activities like health care therefore miss the boat in terms of building a better tomorrow."

"Since growth is an absurd short-lived anomaly, what about leveling out in population, resource use per capita, and adopting a steady-state economy? The problem here is that the rate at which we are depleting one-time resources today is unsustainable. We’re simply spending our bank account without paying attention to the balance and without any source of additional income. Most clearly, forests and wild spaces are down by a factor of two in the last 60 years and will be gone within 60 years at current rates of depletion. Before even getting to steady-state conditions, inevitable near-term increases in population together with sought-after increases in standards of living around the world spell an even shorter lifetime for critical habitats. Meanwhile, fisheries are failing in domino fashion; aquifers are being depleted at rates alarmingly higher than replacement; soils are degrading and arable land is lost; fertilizer depends on a finite resource; habitat loss is resulting in species extinctions far in excess of natural rates. Even the plunder of mineral resources in the seemingly infinite crust is getting harder, only a fleeting century or so into our spree. Sustaining present levels for even a few more centuries is a dubious (i.e., unsubstantiated) proposition. It is practically absurd to imagine sustaining present practices for 10,000 years. Humans simply have not yet demonstrated an ability to maintain a technological society without utter reliance on grossly unsustainable inheritance spending."

"Earth has never in its history had to contend with 8 billion fire apes, intelligent enough to have leveraged power by exploiting and burning one-time resources. We now operate outside the bounds and protections of evolution: in breach of contract, without a map to success. What could possibly convince us that this fireworks show—which has not even come close to standing the test of time—can maintain anything like its current resource impact for the long haul? Humans have demonstrated convincingly that we can live in a primitive state for hundreds of thousands of years. Our present mode is a few-century flash, supported almost entirely by inheritance-spending. Arguing that we have found a new normal is a precarious position that I would not be eager to defend. Parties end. Fireworks shows end. Why would our flash be any different? It’s not just guesswork: what other outcome could result from rapid resource exploitation on a finite planet?"

"We face unprecedented pressures on resources and on our environment, as human population and standard of living both surge on a finite planet. Nature will not allow this trend to continue indefinitely."

"Human population will not be allowed to grow [indefinitely]. Even small growth rates will step up pressure on natural resources, and Earth can only support so much, long-term. Independent of what the “right” number is, once settled, we will not be able to dial it up without imperiling the hard-won success. Even under steady human population, any increase in resource use per person will also not be compatible. In general, growth leads to a dead end: to failure."

"As a jarring illustration of our tendency to value the human side over the prerequisite physical/ecological side, imagine that somehow we manage to emerge from the coming centuries having established a truly sustainable existence. All resources are renewed by nature at the rate of extraction for human needs; population is steady and at a level just tolerable to the planet in terms of indefinite support. Diverse ecosystems are left to thrive in their natural states. But imagine that we are still plagued by cancer and other maladies, so that life expectancy is, say, 90 years. Then what if a team of researchers hits on a cure for (most forms of) cancer? Hurray! At last! Unambiguously good, right? Well, not so fast. All other elements held the same, longer life spans translate to a higher population, putting additional resource burdens on the planet that it cannot handle in the long term. In order to adopt and implement the cure for cancer, we would have to either deliberately reduce population or lower the standard of living to accommodate the change. All other considerations of the complex society about economic impacts, equity of distribution, legal and political facets, or interaction with religious belief systems must take a back seat to the most fundamental and important question: is this change physically viable on this finite planet in the long term?"

"People tend to prefer the narrative that we, ourselves, are the superheroes, and that our superpowers are not from the fossil fuel suit, but are cognitive in nature. Yet we have the same neural hardware (if not slightly downsized) as our prehistoric ancestors. The main cognitive revolution happened about 70,000 years ago when humans started to believe in things that do not exist (like spirits or potential future gains) that allowed large-scale coordination and shared identity to outcompete evolution’s more biophysical tricks of sharp teeth/claws, speed, strength, camouflage, poison, or overwhelming numbers. Global spread of homo sapiens and megafauna extinctions quickly followed, and it is at this point that the human experiment began to smolder: something was off. About 10,000 years ago, agriculture started and the first visible flame ignited. About 300–400 years ago, the Enlightenment lit a fuse by developing a scientific approach to understanding the world. It was not long before the fuse found fossil fuels and we now witness the predictable explosion that ensued. The explosion is breathtakingly rapid on any meaningful timeline, only appearing in slow motion to the few generations experiencing the phenomenon and thus seeming “normal.” So we can trace some part of our current planetary dominance to human ingenuity, but perhaps the lion’s share actually is attributable to the energy bonanza—as suggested by the dramatic change in the pace of innovation before and after the fossil transition."

"A plausible scenario for ecosystem collapse... is based on the fact that we currently support 8 billion people on a fossil-intense agricultural system. We have over-leveraged that finite resource to "borrow" millions of years of eco-services (photosynthetic energy) and now host a population that probably never could have existed in ecological equilibrium. Even if fossil fuels were not going away, it seems likely we would see continued erosion of the globe's ability to support this current unsustainable mode. We have already lost about half of the wild animal life in my lifetime: is that halfway to collapse? Take away the fossil fuels, and I imagine over-hunting and rapid deforestation will take an enormous toll on ecosystem health."

"[It] is truly alarming from an ecological point of view: not only has the human population grown like gangbusters, but the level of affluence per person has soared by an even larger factor."

"The dream of eventually having 10 billion people living at American standards completely ignores the glaring fact that we seem to be circling the drain even at today’s impact level (i.e., overshoot). How could we possibly entertain the factor-of-five increase in resource demand that would accompany a realization of “the dream?” It seems delusional… and likely to turn into a nightmare if pursued."

"Human population is going up… We’re not exactly doing the planet (or ultimately ourselves) any favors presently. Will adding more humans that subscribe to our current cultural model somehow make the situation better? Will improving standards of living (thus increasing resource demand) mysteriously turn things around? It’s hard to see how—not without enacting a whole new model."

"Increasing the standard of living of a growing population makes today’s ecological pressures look adorable."

"It is easy to get caught up in the heady whirlwinds of modernity. We have accomplished amazing feats in these past few centuries, and our extrapolative minds envision a continued acceleration. Given that our life span overlaps only a portion of the tale, it is easy to lose the context that our boom (the Industrial Revolution and what followed) is almost entirely due to fossil fuels. This energy surge in turn powered a surge in material access and economic activity (and human population) in what is perhaps fittingly described as a fireworks show."

"What did we do with our fossil fuel bonanza? We exploded population by revolutionizing agriculture [and health]. Now when fossil fuels inevitably (and soon?) decline, we’re left with an overhang that can no longer be supported. The resulting population decline will suddenly cast Malthus in a new light: oh what a starry-eyed soothe-sayer [sic]! When that day comes, […] realize that it’s no more tragic than the ant colony waning as it must."

"Our fossil fuel bonanza has left our ecosystem in a perilous state. We have destroyed vast forests and habitats, polluted water and soil, kicked off a rapid climate trend that natural systems may not adapt to quickly enough, and basically overrun the planet."

"…fossil fuels allowed us to drastically overshoot the natural carrying capacity of the planet, and that bill will come due when the underlying resource inevitably dwindles. Sometimes simple is simply right."

"The human explosion has accelerated across the millennia, most recently reaching a fever pitch owing to the employment of fossil fuels—leveraging stored solar energy about a million times faster than it was created. The ensuing access to minerals and ability to transform landscapes has rapidly and radically altered our world within just a few human generations."

"In 1800, every human on the planet had a corresponding 80 kg of mammal mass in the wild. Wildland mammals outweighed humans in an 80:50 ratio. Today, each human on the planet can only point to 2.5 kg of wild mammal mass as their “own.” Let that sink in. You only have 2.5 kg (less than 6 pounds) of wild mammal out there somewhere. A single pet cat or dog generally weighs more. Not that long ago, it was more than you could carry. Now, it seems like hardly anything! I especially fear the implications for mammals should global food distribution be severely crippled."

"As if the Enlightenment was not enough, in quick succession we joined another enormous river. One could say that the process of science opened the door to fossil fuels, but science and fossil fuels might be best described as a dynamic duo. Fossil fuels gave us the power to advance our science-amplified degree of control to an entirely new level. Resources that had been previously inaccessible became available. It became far easier to clear land for agriculture and other uses. We learned to make fertilizer from methane, unleashing unprecedented agricultural surpluses that inevitably resulted in a human population overshoot. Fossil-fueled furnaces led to steel, concrete, and other materials on a massive scale, paving the way to megacities and global trade. Science itself was amplified by having access to fossil fuels, via a flood of new devices and capabilities invented with—and powered by—cheap energy. Advances in science and technology in turn allowed greater access to buried fossil energy. This positive feedback arrangement facilitated runaway expansion of the [human] enterprise, leading to a battery of hockey stick curves."

"Energy has been fundamental to our story of growth. The various hockey stick curves over the last century or so are a reflection of energy and population. What’s more, human population itself is a reflection of energy, as mechanized, fertilized agriculture was made possible by fossil fuels. Since energy per capita has also increased like a hockey stick, the ecological impact (and many other metrics like GDP) takes on the shape of a super-exponential (still resembling a hockey stick on a logarithmic plot)."

"We have used [fossil fuels] to expand the human enterprise and population, knock down forests, destroy and fragment habitats, drive extinctions, and generally threaten the vitality of the planet. [But] “solving” the energy problem as fossil fuels give out is pretty frightening: how would it not simply perpetuate the ecological nosedive we have initiated? Only if we put ecological concerns above energy do we stand any chance of survival."

"I acknowledge that cancer is a class of disease, and no universal cure is likely to emerge. But feel free to substitute any longstanding cause of death. […] In a sense, it is death that makes life special and worthy of celebration. […] What would a successful cure look like? Human lifespans would increase. All other things being equal, a reduced death rate means more humans on the planet, putting additional pressures on the entire community of life and further threatening the vitality of the planet—including humans, to be clear. Moreover, access to the cure would almost certainly be more available to the affluent half, who are already heavy users of resources and thus cause outsized harm to the planet. So a cure to cancer would serve to boost ecological destruction, in practice."

"Truly, the end of modernity will probably be brutal for most of the 8 billion people on the planet, who will cling to what they know and fail to adapt. But even if they were mentally ready, the Earth is not ready to support 8 billion humans without a massive fossil subsidy, so human population will likely fall a lot in hard times."

"Compared to biologically relevant timescales, the human explosion commenced just “yesterday” when grain agriculture began taking root... set[ting] the stage for planet-crushing present-day human populations in a time that is still contextually short. Each “improvement” like cities and technology only accelerated the rapidity of the unsustainable ascent. Mounting ecological damage was part and parcel of this expansionist story long before cars, planes, and smartphones arrived—like two sides of a coin."

"Humans are voracious (big brains to feed and a lot of un-furry surface area to keep warm), and therefore are ecologically expensive. If the Earth tightens its belt, [one should]n’t assume that humans will fare well. We are summer children borne of “good” times, where “good” translates to “biodiverse.” Cleverness is no guarantee against starvation, as countless clever humans who have starved can’t tell [us]."

"[Our] success [in eliminating hunger and inequity] inevitably grows the population, scaling up the current tension... to planetary limits... [and] curing all diseases and achieving effective immortality would be ecologically disastrous!"

"Since the current low levels of mortality go hand-in-hand with ecological devastation and a doomed modernity, their embrace is itself a problem…"

"The Green Revolution transformed agriculture by inserting fossil fuels at every turn. Fertilizer came from natural gas. Diesel allowed large-scale mechanization of plowing, planting, harvesting, processing, and transporting large amounts of food. Petrochemical pesticides smote economically worthless (but ecologically invaluable) products of evolution into the foul dust. We fed a growing human population, now 8 billion strong. It boils down to a diet of fossil fuels: again, temporary."

"To those who resist the notion that increasing food production also means increasing human population, consider this. In 1950, the global population stood at about 2.5 billion people. The Green Revolution was about to explode into global agriculture, substantially increasing crop yields on the back of profligate fossil fuel inputs (for fertilizer, mechanization, energy for irrigation, transport, processing, etc.). Let’s say this tsunami of energy and technology had not arrived on the agricultural scene, and that moreover a global edict (“magically” followed) held annual food production at the 1950 level thereafter. Would we have 8 billion people today? Impossible. We would still have 2.5 billion, correct? In 1950, the world produced enough food for 2.5 billion people, so that same amount of annual food would sustain 2.5 billion people today…or perhaps 2 billion taller, heavier people; or 3 billion people with more equitable, modest distribution and less waste. But you get the point: hold the food supply steady and you essentially hold the population below some cap. Inarguable. Those additional 5.5 billion people were made possible by a technological wave of food increase."

"[Eight] billion humans are driving a sixth mass extinction, which leaves no room for even 10 humans if fully realized, let alone 10¹⁰."

"Maintaining 8 billion human people on Earth [without fossil fuels] is no more possible than invading space. It’s not an actual, realizable choice—beyond transitory and costly stunt demonstrations."

"How we live and consume matters just as much as the growing density of our numbers combined with the proliferation of our machines that devour energy on our behalf. (Roads and cell phones all consume energy and materials too.) All three demographic issues are increasing at unsustainable rates and feed each other to propel more economic growth, more emissions and more fragility. The world’s current population is 7.9 billion and grows by 80 million a year. It has slowed down in recent years because the affluent don’t need the energy of children as much as the poor. Even so civilization will add another billion to the planet every dozen years. Redistributing energy wealth (and emissions) from the rich to the poor will not avert disaster if human populations don’t overall decline. Our numbers also reflect a demographic anomaly that began with fossil fuels, a cheap energy source that served as Viagra for the species. Prior to our discovery of fossil fuels, the population of the planet never exceeded one billion. Our excessive numbers are purely a temporary artifact of cheap energy spending and all that it entails — everything from fertilizer to modern medicine."

"In recent decades, support for family planning has waned, and global fertility decline has decelerated as a result. Projections calibrated across the decades of strong family planning support have not acknowledged this change and are consequently underestimating global population growth. Scenarios used to model sustainable futures have used overly optimistic population projections while inferring these outcomes will happen without targeted measures to bring them about. Unless political will is rapidly restored for voluntary family planning programs, the global population will almost certainly exceed 10 billion, rendering sustainable food security and a safe climate unachievable."

"Putting an end to the population explosion will not of itself save the ecosphere, but not ending it will add greatly to the dangers the planet faces. The environment can sustain a quality of life for just so many people."

"In what year will the human population grow too large for the Earth to sustain? The answer is about 1970, according to research by the . In 1970, the planet's 3 and a half billion people were . But on this New Year's Day, the population is 8 billion. Today, wild plants and animals are running out of places to live."

"... Homo sapiens have been around for about 200,000 years and we are struggling to provide 7 billion of us with sufficient food, clothing, and shelter to lead decent lives. There cannot be an economist on the planet who thinks Earth could support 7.168 trillion people. Human population growth cannot go on forever, no matter how optimistic economists might be."

"Human overpopulation, the ever-increasing power of our technology, and the demand of our omnicidal, neoliberal economic system of infinite growth on the basis of finite resources threaten the earth with total destruction."

"Ever since Malthus, at least, it has been clear that means of subsistence do not grow as fast as population. No one has ever liked the idea that famine, plague, and war are nature's way of redressing the imbalance -- Malthus himself suggested that the operation of "preventive checks," which serve to reduce the birth rate, might help prolong the interval between such events. And in the two hundred years since Malthus sat down to pen his essay, there has been no worldwide cataclysm. But in the same two centuries world population has grown exponentially while irreplaceable resources were used up. Some kind of adjustment is inevitable. Today, many people who are concerned about overpopulation and environmental degradation believe that human actions can avert catastrophe. The prevailing view holds that a stable population that does not tax the environment's "carrying capacity" would be sustainable indefinitely, and that this state of equilibrium can be achieved through a combination of birth control, conservation, and reliance on "renewable" resources. Unfortunately, worldwide implementation of a rigorous program of birth control is politically impossible. Conservation is futile as long as population continues to rise. And no resources are truly renewable."

"Around 8,000 BC, world population was something like five million. By the time of [the birth of Jesus] Christ, it was 200 to 300 million. By 1650, it was 500 million, and by 1800 it was one billion. The population of the world reached two billion by 1930. By the beginning of the '60s it was three billion; in 1975 it was four billion; and after only eleven more years it was five billion. This cannot go on forever; collapse is inevitable. The only question is when."

"People who believe that a stable population can live in balance with the productive capacity of the environment may see a slowdown in the growth of population and energy consumption as evidence of approaching equilibrium. But when one understands the process that has been responsible for population growth, it becomes clear that an end to growth is the beginning of collapse. Human population has grown exponentially by exhausting limited resources, like yeast in a vat or reindeer on St. Matthew Island, and is destined for a similar fate."

"As human populations expand they necessarily appropriate ecological space required by other species. Human ‘competitive displacement’ of non-human organisms from their habitats and food sources is now the greatest contributing factor to . Consider that with only 0.01 % of total Earthly , H. sapiens’ expansion has eliminated 83 % of wild animal and 50 % of natural plant biomass. From a fraction of 1 % ten millennia ago, humans now constitute 36 %, and our domestic livestock another 60 %, of the planet’s much expanded mammalian biomass compared to only 4 % for all wild species combined. Similarly, domestic poultry now comprise 70 % of Earth’s remaining avian biomass. Meanwhile, commercial fishing depletes the oceans at the expense of rapidly declining marine mammals and birds. Seabirds are the most threatened bird group, with a 70 % community-level population decline between 1950 and 2010."

"Population estimates are usually based on demographic data alone with no consideration of exogenous factors. This is unrealistic. For living organisms, the fact of their own existence ensures that no environment or habitat remains ideal for long. As the subject population expands, it will invariably use up any crucial resource in fixed supply. Even renewable resources can be depleted once the population goes into ‘overshoot’, a situation in which aggregate consumption exceeds food species’ recovery rates or waste accumulation exceeds natural assimilative capacity. The rise and fall of reindeer populations introduced to two previously unoccupied (by reindeer) Pribilof Islands in the early 20th century is a classic example. Collapse was attributed to overgrazed food sources (primarily lichen) abetted by the stress of exceptionally cold winter."

"...for most of our species’ time on Earth—including most of the agricultural era—humanity’s natural propensity to expand has been held in check by negative feedback, e.g., food and other resource shortages, disease, and inter-group conflict. Circumstances changed with the scientific/industrial revolution, particularly the increasingly widespread use of fossil fuels. It took 200,000 – 350,000 years for human numbers to reach one billion early in the 19th Century, but only 200 years (as little as 1/1750th as much time!) to balloon another seven-fold by early in the 21st Century. Improvements in medicine, public sanitation, and population health contributed to this expansion, but coal, oil, and gas made it possible. Fossil fuels are the energetic means by which humans extract, transport, and transform the prodigious quantities of food and other material resources into the products needed to support our burgeoning billions. More than any other factor, fossil fuels enabled H. sapiens to eliminate or reduce normal negative feedbacks. Freed from historic constraints, our species was, at last, able to exhibit its full potential for geometric growth."

"Humanity is already far into ecological overshoot: we are learning the hard way that the ecosphere under stress is still immeasurably more complex than even the global human enterprise. It can generate a vastly larger arsenal of negative feedbacks in response to human excesses than any imaginable human control system can match."

"Humans invade and populate all accessible favourable habitats; human populations use up all available resources; under favourable conditions, human populations are capable of exponential growth. […] The industrial/scientific revolution spawned technologies, particularly improvements in public sanitation and disease control, that greatly reduced death rates while fossil fuels alleviated food and resource shortages. With the suppression of negative factors, positive feedback prevailed; between the early 1800s and 2023, the human population exploded from one to eight billion. Meanwhile, what we now call ‘neoliberal economics’ began taking form in the late 1800s. In just two centuries, the human population grew eight times larger than the maximum attained over the previous 3000 centuries, and the world economy grew 100-fold in real terms! […] Overshoot may be a quasi-natural phenomenon, but it is also a potentially terminal condition. There are now about 80 cities in the world with populations in excess of five million—each has more people than existed on the entire planet at the dawn of agriculture 10,000 years ago. […] Life in higher-income countries just seemed to be getting better and better, at least in material terms. Little wonder that by the 1950s, MTI governments and international institutions everywhere were adopting the neoliberal vision of perpetual economic and population growth via continuous technological advance as the dominant development narrative of global culture. There are, of course, significant problems—all this occurred on a finite, non-growing planet with serious history. With nurture-reinforcing-nature in propelling the expansionist juggernaut, the human enterprise surged into ecological overshoot; resource consumption and waste production are overwhelming the bio-productive and waste assimilation capacities of the ecosphere. This is not merely an aesthetic concern: the functional integrity of the ecosphere is essential for human existence. Overshoot may be a quasi-natural phenomenon, but it is also a potentially terminal condition."

"The current human population is 14,000-fold larger than the average populations of other mammal species of similar body size! […] If humans were a typical mammal whose global population corresponded to the arithmetic mean (average) of populations of mammals of similar body size, there would be only 500,000 people on Earth!"

"Almost all of today’s low-energy countries have a population density so great that it perpetuates dependence on intensive manual agriculture, which alone can yield barely enough food for their people. They do not have enough acreage, per capita, to justify using domestic animals or farm machinery, although better seeds, better soil management, and better hand tools could bring some improvement. A very large part of their working population must nevertheless remain on the land, and this limits the amount of surplus energy that can be produced. Most of these countries must choose between using this small energy surplus to raise their very low standard of living or [to] postpone present rewards for the sake of future gain by investing the surplus in new industries. The choice is difficult because there is no guarantee that today’s denial may not prove to have been in vain. This is so because of the rapidity with which public health measures have reduced mortality rates, resulting in population growth as high [as] or even higher than that of the high-energy nations. Theirs is a bitter choice; it accounts for much of their anti-Western feeling and may well portend a prolonged period of world instability."

"The doubling of life expectancy is largely down to medical advances. Without medical care, we’d probably be at a much lower population level. I can’t find projections, but given that even some fairly routine injuries and sicknesses would be life-threatening without medical intervention, one would expect a more pyramidal pyramid, and 2 billion people doesn’t seem unreasonable to me. This is also amplified by [there] being [fewer] people to innovate ideas like the green revolution, which [led] to higher populations. In nature, population overshoot is usually remedied by a higher die-off rate, not a lower birth rate. But humans think that medical care and increased lifetimes are a sign of progress. Medical advances can even allow some who wouldn’t have been able to have children to have children, thus exacerbating overshoot."

"A lot of technologies have been utilised in storing food or growing more of it. And we know that increased access to food increases population size. The reverse is also true, of course, so we should expect population to fall as harvests come under stress from the effects of climate change."

"Humans are a species, so they are no different in needing to reproduce to propagate their traits, which may eventually lead to what would be considered a new species, though that would likely take tens or hundreds of thousands of years. If our ancestors had considered the effects of what they were doing, why some prey species appeared to disappear, for example, then we wouldn’t be here, as we’d limit what we did, how we expanded, how we spread. Humans would, at best, have remained a very limited species, if it survived at all. But that is not the way life works. Clearly, we have followed the maximum power principle, since we’re a species, and so consume as much energy and resources as we can. In basic terms, a body needs food for energy and humans have figured out how to produce increasing quantities of food (at least in terms of calories) using agriculture, machines, artificial fertilisers and pesticides. This has enabled an explosion in population in a positive feedback loop (with higher population forecast, we figure out how to support that population, leading to more agriculture and higher yields, so we end up with a higher population). The huge success of agriculture and mechanisation, has lead to almost no human being involved in the production of the food that keeps us alive, so we’ve had to invent other ways to kill our time. We now have a huge variety of products and services to help us kill our time before we die. Some of it is pleasurable so we want to do more of it and invent new ways to live. All the time, killing more of the rest of life. But getting here was inevitable because we are a species and don’t have free will to counter those inbuilt drives."

"As food makes babies perhaps the critical development was agriculture but then without fossil fuels, we could never have produced as much food as we do now, and deliver it across the world. But then, if we hadn’t started cooking food, we might not have been clever enough to figure out how to use fossil fuels to produce food. And without language, we could never have communicated complex ideas about agriculture, tool making and the use of fossil fuels. So we go round and round."

"It is often said that humans are in overshoot. What does that mean? In simple terms, it means exceeding a limit. However, if a limit has been exceeded, then how is it a limit? People usually refer to overshoot as exceeding the carrying capacity of the planet. The ability for the planet to support the current population of humans. And yet here we are. Humans have apparently been in overshoot territory for a long time, but that hasn’t affected the numbers. Indeed, the population of humans continues to grow."

"We have well over 8 billion people on this planet. All ecosystems have been perturbed, and wildlife has been hugely depleted by over 70% in just the last half century. Deforestation continues apace at almost 5 million hectares per year. So, it’s impossible for all humans to live sustainably right now. If a few chose, and succeeded, to live sustainably, it would have no measurable effect on the planet."

"It is apparently futile only to insist that the more back­ward countries restrict their birth rates. What is needed most of all is economic and technical assistance to these countries. This assistance must be of such scale and generosity that it is unlikely before the estrangement in the world and the egotistical, narrow-minded approach to relations between nations and races are eliminated."

"Government policy, legislation on the family and marriage, and propaganda should not encourage an increase in the birth rates of advanced countries while demanding that it be curtailed in underdeveloped countries that are receiving assistance. Such a two-faced game would produce nothing but bitterness and nationalism."

"I want to emphasize that the question of regulating birth rates is highly complex and that any standardized, dogmatic solution "for all time and all peoples" would be wrong."

"...increasingly, technology has come up against the law of unexpected consequences. Advances in health care have lengthened life spans, lowered infant-mortality rates, and, thus, aggravated the population problem."

"As human beings, with over 8 billion of us on planet Earth at present, we now find ourselves in a very analogous situation to both the early cyanobacteria from over 2 billion years ago and the yeast cells one would culture within a nutrient-rich broth in a petri dish. It isn’t that we’re in danger of transforming our planet into an uninhabitable hellscape, as nothing we’ve done or are in the process of doing is going to have a catastrophic effect of that magnitude. However, there are a number of ways that we’re polluting, destroying, or depleting our environment in ways that not only are non-renewable and unsustainable, but that are going to have negative downstream effects that impact future humans, hundreds and even thousands of years down the line, in ways that most of us aren’t prepared to fully reckon with. And that’s unfortunate, because we should be prepared. After all, unlike yeast, cyanobacteria, or any other species that’s impacted its environment due to its collective, accumulated actions, we can not only detect and quantify the effects we’re having, but can choose to change our action at any time."

"Erroneous belief about population growth has cost dearly. In poor countries, it has directed attention away from the factor that we now know is central in a country's economic development, its economic and political system. And in rich countries, misdirected attention to population growth and its... consequence of natural-resource shortages has caused waste through such programs as now-abandoned synthetic fuel programs, and the useless development of airplanes that would be appropriate for an age of greater scarcity."

"Adding more people causes problems, but people are also the means to solve these problems. The main fuel to speed our progress is our stock of knowledge, and the brake is our lack of imagination. The ultimate resource is people—skilled, spirited, and hopeful people who will exert their wills and imaginations for their own benefit, and inevitably they will benefit not only themselves but the rest of us as well."

"Capitalist elites seeking to increase the size of their labour force used pro-natalist state policies to prevent women from practicing family planning. [...] We should not ignore the relationship between population growth and ecology, but we must not treat these as operating in a social and political vacuum."

"History upon Terra tells us what horrors follow upon religious mandates of unlimited reproduction."

"Malthusian predictions that relentless population growth will outstrip food production and trigger starvation worldwide have recurred over the centuries. They have come and then gone as farmers have deployed new technologies to increase food output. Even now, enough food is being produced to adequately feed every person on the planet; the fact that nearly one billion people are nonetheless going hungry is a damning indictment of the world's food-distribution system. But since demand is growing, production will also have to increase in the years ahead. With the world's population expected to expand to more than nine billion by 2050 and much of that growth occurring in China, India, and other countries where living standards are rising fast, global food production will need to increase by 70-100 percent in order to keep pace and feed the already chronically hungry. This is a mighty challenge: all the more so because given current soil technology and environmental concerns, more food will have to be produced on roughly the same amount of arable land -- and with less water than is used now and at a time when both growing demand for biofuels and changing climate patterns are also putting pressure on production. Where will the needed rise in food supplies come from, and how quickly can the distribution problems be solved?"

"Given the Maoist position that a large population was a “resource”, rather than a burden, for the Communist state, it was politically incorrect to advocate population control [either by diet or medicine]."

"Supporting large families and unchecked growth (of which the greatest parameter is population increase) is a mantra which religion and authority have preached for thousands of years. Religions always need more clergy to reap donations from, and leaders more voters to turn into soldiers for their next war, or to make the gross (as opposed to per capita) GDP figures look good. We are being farmed, we have always been farmed for thousands of years by an economic system that prioritises cold hard profit figures over real prosperity. Competition fuels growth even more, as humans are extremely territorial. The problem with the existence of countries is that they speed up civilisational collapse. They all end up competing for economic and population growth, therefore significantly accelerating civilisational overshoot and collapse."

"Thanks to the discovery and exploitation of fossil fuels, humans (really just a small minority of them) are able to live richer lives today than even the queens and kings of yore could have dreamed of. Furthermore, we’ve used some of those finite resources to increase food supplies and to expand the human population, which provides the economic system with both more workers and more consumers, a necessity to keep the economy growing under our current economic model. The world’s population increased from 1.6 billion in 1900 to 7 billion today, and we add about 80 million more each year. Humans have quickly become the most numerous megafauna on the planet."

"Humans, because of their intelligence, have found ways to [temporarily] defeat survival of the fittest. As areas get overpopulated, humans have moved to areas where they have a better chance of survival. Humans have found ways to increase food supply, through the use of fertilizers, pesticides, irrigation, and refrigeration, all of which require fossil fuels. They have developed trade, so that so areas with shortfalls can benefit from surpluses elsewhere. Humans have developed a world financial system, which has helped enable worldwide trade. The financial system has also allowed investors to pay for goods after they are put into service, so that the cash flow resulting from an investment can be used (after the fact) to pay for the cost of the investment. This enables investment, and faster use of resources, including energy resources. One of the reasons for continued upward population pressure is the fact that humans have evolved to live beyond their reproductive years. In their declining years, humans often need assistance, either from their offspring or from a public pension program, or both. Because of concern for their own old age, people without pensions tend to have enough children so that there is a significant chance that a child of the right sex will survive to adulthood. With improving medical care, this tends to lead to [an] ever-rising population."

"As long as the world’s population is rising, even in lesser developed countries, there is going to be a continuing need for more food, clothing and housing. This is an issue we don’t seem to be able even to talk about. It may offend people."

"The energy resource that we learned to develop this time is fossil fuels, starting with coal about 1800. World population was able to expand greatly because of additional food production permitted by fossil fuels and because of improvements in hygiene. A period of stagflation began in the 1970s, when we first encountered problems with US oil production and spiking oil prices. Now, the question is whether we are approaching the Crisis Stage as described by Turchin and Nefedov."

"As energy supplies deplete, we will increasingly need to “choose our battles.” In the past, humans have been able to win many battles against nature. However, as energy per capita declines in the future, we will be able to win fewer and fewer of these battles against nature, such as our current battle with COVID-19. At some point, we may simply need to let the chips fall where they may. The world economy seems unable to accommodate 7.8 billion people, and we will have no choice but to face this issue."

"Many people believe that humans can have a sustainable future by using solar panels and wind turbines. Unfortunately, the only truly sustainable course, in terms of moving in cycles with nature, is interacting with the environment in a manner similar to the approach used by chimpanzees and baboons. Even this approach will eventually lead to new and different species predominating. Over a long period, such as 10 million years, we can expect the vast majority of species currently alive will become extinct, regardless of how well these species fit in with nature’s plan. The key to the relative success of animals such as chimpanzees and baboons is living within a truly circular economy. Sunlight falling on trees provides the food they need. Waste products of their economy come back to the forest ecosystem as fertilizer. Pre-humans lost the circular economy when they learned to control fire over one million years ago, when they were still hunter-gatherers. With the controlled use of fire, cooked food became possible, making it easier to chew and digest food. The human body adapted to the use of cooked food by reducing the size of the jaw and digestive tract and increasing the size of the brain. This adaptation made pre-humans truly different from other animals. With the use of fire, pre-humans had many powers. They spent less time chewing, so they could spend more time making tools. They could burn down entire forests, if they so chose, to provide a better environment for the desired types of wild plants to grow. They could use the heat from fire to move to colder environments than the one to which they were originally adapted, thus allowing a greater total population. Once pre-humans could outcompete other species, the big problem became diminishing returns. For example, once the largest beasts were killed off, only smaller beasts were available to eat. The amount of effort required to kill these smaller beasts was not proportionately less, however."

"… the problem the world is facing today is like one that smaller economies have faced, over and over, in the past: The population has become too large for the economy’s resource base, which now includes fossil fuels. Today’s leaders reframe the problem as voluntarily moving away from fossil fuels to prevent climate change in order to make the situation sound less frightening."

"We are dealing with an age-old problem: Humans are able to outsmart other animals, and for this reason, human populations tend to rise except when external conditions are quite adverse."

"History shows a repeated pattern of overshoot and collapse. A population would grow until the carrying capacity of the local area was reached. Food surpluses would become lower and lower, so less food could be saved up for fluctuations in rainfall and temperature. Eventually, civilizations would succumb to one or another problem: disease, attack by a neighboring group, climate fluctuations, or governments overthrown by unhappy citizens. We tell ourselves that overshoot and collapse cannot happen now, but human population is high relative to fossil fuel resources, and intermittent wind and solar are not working out well as substitutes."

"Humans are smarter than other animals, allowing the population of humans to grow, while the population of many other species tends to fall. […] The large rise in the population of the less advanced economies contributes to the huge number of immigrants wanting new homes in higher-income countries. […] The issue is that available resources do not rise fast enough (in the area, or with the technology available) to provide enough physical goods and services for the population. If a new approach can be developed, or a neighboring area with additional resources can be conquered, [the] population can start to grow again. […] Outgrowing our resource base is not a phenomenon that began with fossil fuels. […] In 1796, when [the] world population was about one billion, Robert Thomas Malthus wrote about population growing faster than food production. This was before fossil fuels were widely used. Now, about 230 years later, [the] population has risen to eight billion, thanks to the availability of fossil fuels. We need major innovations, or additional energy resource types, if we want to work around obstacles now."

"The hard fact is that in an age of climate breakdown, human numbers matter. And the ecological impact of another 2-3 billion humans will be immense."

"We must look at the whole man, and at his whole environment. Above all, we must realize that every grain of rice he puts into his mouth, every bit of potato, every piece of meat, and every kernel of corn, must be replaced by another bit from the earth—somewhere. We must realize that not only does every area have a limited carrying capacity—but also that this carrying capacity is shrinking and the demand growing. Until this understanding becomes an intrinsic part of our thinking and wields a powerful influence on our formation of national and international policies we are scarcely likely to see in what direction our destiny lies."

"[There's] too many people making too much muck and too much noise with too little space to do it in."

"Today, escalating human populations have vastly exceeded global carrying capacity and now produce massive quantities of solid, liquid, and gaseous waste. Biological diversity is being threatened by over-exploitation, toxic pollution, agricultural mono-culture, invasive species, competition, habitat destruction, urban sprawl, oceanic acidification, ozone depletion, global warming, and climate change. It’s a runaway train of ecological calamities."

"Homo sapiens’ appetite is gargantuan. As we strive to get at dwindling resources for ever more people, we dig deeper into the Earth, blow the tops of mountains, divert rivers, cut down forests and pave over swaths of land. We fill the land, water, and air with our pollution. We’re driving record numbers of species to extinction and decimating others with activities from chemical poisoning to hunting for bushmeat, or simply by taking over their habitat. Greenhouse gases from our industry are changing the Earth’s climate, with such dangerous consequences as ocean acidification, rising sea levels and flooding, changes in rainfall patterns including in vital “breadbaskets,” and loss of forest cover. While the word “sustainable” has become popular, growing human numbers and activities are anything but. Increasing awareness of our impact has led to developments in renewable energy, recycling, earth-friendly farming and more. There have also been spectacular advances in family planning. But powerful—notably religious—opposition has kept governments and international bodies from actively promoting small families and prevented hundreds of millions of women who would plan their families from having access to modern methods. Those who deny that overpopulation is a problem say the poor don’t consume much. Yet the poor want nothing more than to consume more, as proved by India and China. Who can blame them? And a burgeoning number of desperately poor people does have a major impact: they cut down forests to grow food, drain rivers, deplete aquifers, and overfish and over-hunt in their local area. But make these points and you’ll be accused of blaming the poor for the problems of the rich. We seem bound to learn the hard way that there really is a limit to how many people the Earth can support. We wish it weren’t so, but it really is starting to look as if Malthus was right."

"...the gains of low infant and maternal mortality and rises in population longevity—brought about in great part by harnessing fossil fuels, the agricultural revolution, modernization, and disease and injury reduction efforts—in many instances impedes rather than facilitates moving toward sustainable living. It can be argued from the ecological perspective that most public health efforts, as humanitarian as they are by intention and immediate effect, through accelerating population pressures on the environment are paradoxically hastening the destruction of the earth's habitat on which the next generation of humanity depends. It raises the concern that our perceived gains may be only illusory and temporary, with huge but unmeasured and unlinked environmental costs that will eventually lead to shorter lives of misery for our descendants."

"In the past, when one civilization collapsed, others evolved to replace it. Today the world-wide agroindustrial complex is making unprecedented demands on the whole earth’s biological ecostructure. After a brief half-century in which factory farming enlarged the meagre diet of the poor (though not for all, nor always to their benefit), the multinational food industry has become a primary impetus towards overpopulation, obesity, pollution, and global warming. Policies and practices whose effects were once circumscribed are now a threat to human survival."

"Agriculture, by overcoming the limitations inherent in the closed system of hunting/gathering, made possible the open-ended expansion of both the population and the means of feeding it. Once it had been adopted, there was no turning back. The more that a civilization farmed, the more it needed extra hands, and so large families were deliberately procreated, which in turn produced still more mouths to feed. Colin Tudge calls it a vicious spiral, Ronald Wright a progress trap."

"Nature’s modus operandi is to kill off the weakest, leaving only the strongest and most biologically versatile to reproduce. But for homo sapiens, nature is not a force to be accommodated, but an opponent to be grappled with, and so ‘farming for money’ was joined by ‘medicine for money’. On top of the lucrative agroindustry which accellerates the population explosion, we have set up an equally profitable ‘health’ industry whose job it is to keep alive those whose bodies rebel at what they are so unhealthily force-fed. The result is an expanding segment of the population who, along with accellerating obesity, suffer from various diseases of malnutrition, together with allergies and intolerances to a growing list of foodstuffs that are increasingly difficult to avoid. In the end, humanity may consist of a remnant of survivors who spend their brief unhappy lives closeted against the encroaching poisons which their ancestors had so profitably created. Instant death by peanut may prove to have been a warning blip on the radar screen."

"Today the threat lies in the sheer scale of our greed and our technological ineptitude. We’re driving entire countries over cliffs. We are destroying the delicate ecological balance which a [sic] brief interlude of stable climate has allowed us. We make pious noises about the disappearing terrestrial species while largely ignoring the invisible havoc we’re bringing about in the earth’s oceans, the source and sustenance of life on the land."

"The raging monster upon the land is population growth. In its presence, sustainability is but a fragile theoretical construct. To say, as many do, that the difficulties of nations are not due to people but to poor ideology or land-use management is sophistic. If Bangladesh had 10 million inhabitants instead of 115 million [as of this writing], its impoverished people could live on prosperous farms away from the dangerous floodplains midst a natural and stable upland environment. It is also sophistic to point to the Netherlands and Japan, as many commentators incredibly still do, as models of densely populated but prosperous societies. Both are highly specialized industrial nations dependent on massive imports of natural resources from the rest of the world. If all nations held the same number of people per square kilometer, they would converge in quality of life to Bangladesh rather than to the Netherlands and Japan, and their irreplaceable natural resources would soon join the seven wonders of the world as scattered vestiges of an ancient [sic] history."

"The pattern of human population growth in the 20th century was more bacterial than primate. When Homo sapiens passed the six billion mark we had already exceeded by perhaps as much as 100 times the biomass of any large animal species that had ever existed on the land. We and the rest of life cannot afford another one hundred years like that."

"If we fail to limit our numbers and our impact, if we do not replace our goldrush economics with a rational sharing of what the earth can yield, this new century will not grow very old before we enter an age of chaos and collapse that will dwarf all dark ages in our past."

"So among the things we need to know about ourselves is that the Upper Palaeolithic period, which may well have begun in genocide, ended with an all-you-can-kill wildlife barbecue. The perfection of hunting spelled the end of hunting as a way of life. Easy meat meant more babies. More babies meant more hunters. More hunters, sooner or later, meant less game. Most of the great human migrations across the world at this time must have been driven by want, as we bankrupted the land with our moveable feasts."

"What determines population growth? What has been the cause of the unprecedented growth in world population in our recent history? Many socio-economic reasons are given as explanations: medical advances, improvements in public health, sanitation and hygiene, increased food availability and agricultural productivity, extension of cultivation, and development of trade and transportation. Surprisingly, high quality energy sources are rarely mentioned or quickly discounted. Yet an argument can be made that each of the above factors contributing to population growth is aided and influenced by high quality energy supplies. Cheap and abundant fossil fuels have been a necessary precondition for the past century’s population growth. And while not all countries benefit directly from the consumption of high quality energy supplies, most countries benefit from the impact of high energy societies on low energy societies. What if energy consumption, or more precisely, energy resource availability, somehow determines population growth? Perhaps energy resources determine the Earth’s carrying capacity, or how many people the Earth can support? Perhaps different energy resources have different effects on population growth? If we hypothesize that the Earth’s population is ultimately determined by availability of energy resources, and if some of those energy resources are at or near their peak rates of production, then that may affect rates of population growth. If the correlation is strong enough, the number of people the Earth can support may also be at or near its peak. Therefore the number of people in 2050 may be very different from widespread United Nations (UN) forecasts. Growing populations consume more energy. Availability of energy allows populations to grow. Energy consumption exerts demands on energy resources making them scarcer. They become harder to extract. Nearby forests are depleted, coal mines must dig deeper, oil has to be drilled in more complex environments. In other words, energy resource extraction experiences declining marginal returns. This has led to the exploitation of new energy sources, which in turn expands the Earth’s carrying capacity. Then populations grow once more."

"Mature populations tend to reach equilibrium – the carrying capacity – and then fluctuate around this equilibrium. If a population outgrows its carrying capacity, regulating factors come into play, such as famine, or emigration. If a population is below its carrying capacity, birth rates tend to increase, so the population grows. The common assumption is that carrying capacity is determined by the availability of food, water and land. While availability of food and water are important factors in determining the carrying capacity of populations, they cannot explain the unprecedented increases in population that have occurred in the last several hundred years. The availability of land has always been a factor in increasing carrying capacity. In the historic past, the Earth’s carrying capacity could be increased by expanding into sparsely occupied, or frontier, lands. In a fictitious future, carrying capacity could be increased by expanding outward to other planets or solar systems. At present, there is very little unoccupied, habitable land remaining on this Earth and no nearby habitable planets to release the pressure of population growth, so any increase in carrying capacity must be a result of other factors."

"At present the world’s population is growing rapidly. The planet could not support the six billion plus people that exist today without first the commercialisation of coal, then of oil and, more recently, gas. These energy sources have been necessary for the unprecedented population growth that has occurred over the last three hundred years. It is reasonable to assume that unless current energy resource production is increased and new resources are exploited, the population will no longer grow. And if energy resources decline (e.g. a peak in production is reached), then we may see a decline in population."

"Roughly 10,000 years ago, increasing population pressure on wild food resources led to a shift from food gathering (hunter-gatherers) to food production (agriculturists) in several parts of the world. This led to demand-induced technologies and demand-induced searches for higher quality energy sources, such as water power for flow irrigation, animal draft power, iron tools, and fire for land clearing and for improvement of hunting and pastoralism. Population pressures in many parts of Europe in the seventeenth and eighteenth centuries led to serious shortages of wood which in turn led to many of the technological innovations that fuelled the Industrial Revolution. Coal’s replacement of wood as the most important source of energy in Western Europe is a classic example of demand-induced innovation…promoted by population pressures on forested land in Western and Central Europe. From the end of World War II, coal’s premier importance as an energy source declined sharply and was replaced by crude oil. Far offshore drilling of oil began in 1947 off the coast of Louisiana. One year later, the world’s largest oil field, al-Ghawar in Saudi Arabia, was drilled. Large new discoveries of oil and gas in Africa and Asia combined with the development of oil super tankers and pipeline networks reduced the price of oil and gas at a time when the costs of producing coal were continuing to rise. Diesel locomotives represented a major substitution of oil for coal. The post World War II era also saw large increases in automobile ownership, the beginnings of highway and motorway road transportation networks and the first passenger jet aircraft –all benefiting from and encouraging consumption of cheap oil supplies. These increases in the consumption of crude oil have coincided with the highest population growth in history. After the depressed population growth during World War II, growth rose quickly to a peak of 2.2% in 1964, the highest rate the world has ever known. (Per capita oil consumption peaked shortly thereafter, in the 1970s). Although population continues to rise, population growth has been declining since then. If there is a relationship between energy consumption and population growth, the different types of energy consumed may have different effects. If biomass is the only energy source, populations will not grow very fast. In such organically based economies, the problem of expanding raw material supply, and especially the related problems associated with the very modest energy supply maxima…must curb growth with increasing severity as expansion takes place. The emergence of coal as an energy source eliminated the carrying capacity limits to population growth that any traditional and biomass energy based culture would eventually face. Similarly, the predominance of oil after the middle part of the twentieth century raised the carrying capacity even further."

"According to the IEA [International Energy Agency], 1.6 billion people live without electricity. Much of Africa and Asia still rely on biomass as their primary source of energy, yet have very high population growth rates. How can there be a correlation between energy and population in these instances? While many developing world countries remain low energy societies, they, and their population growth rates, are impacted by high energy societies. Their primary energy sources may still be traditional biomass, but their population growth is due in large part to abundant oil and gas supplies. Vaccines and antibiotics that reduce third world mortality are discovered, produced and distributed with first world energy, and oil contributes at every step. Fertilisers, pesticides and herbicides that aided the Green Revolution in much of the developing world could not have been produced without large oil and gas inputs. The aeroplanes, boats and trains that deliver and distribute food all run on oil. While the commercialisation of higher quality energy sources may be very unevenly distributed, the societies that adopt new energy sources, high energy societies, have a profound impact on those societies that remain low energy societies, and these impacted populations then become part of Coal, Oil or Natural Gas Populations."

"Just 11,000 years ago, there were only roughly 5 million humans who lived on the planet Earth. The initial population growth was slow, due largely to the way humans were living—by hunting. Such lifestyle limited the size of family for practical reasons. A woman on the move cannot carry more than one infant along with her household baggage. When simple birth control means-often abstention from sex failed, a woman may elect abortion or, more commonly, infanticide to limit the family size. Further, a high mortality among the very young, the old, the ill and the disabled acted as a natural resistance to a rapid population growth. Thus it took over one million years for human population to reach the one billion mark. But the second billion was added in about 100 years, the third billion in 50 years, the fourth in 15 years, and the fifth in 12 years. Ever since humans became sedentary, some limits over the family size were lifted. With the development of agriculture, children may have become more of an asset to their families in helping with farming and other chores. By the beginning of the Christian era, human population grew to about 130 million, distributed all over the Earth. By 1650, the world population had reached 500 million. The process of industrialization had begun, bringing about profound changes over the lives of humans and their interactions with the natural world. With improved living standard, lowered death rate and prolonged life expectancy, human population grew exponentially. By 1999 there were about 6 billion people, comparing with 2.5 billion in 1950. The world population is well on its way to 7 billion with an annual growth rate of over 90 million."