Overpopulation

"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."

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

"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."

"...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."

"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."

"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."

"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)."

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

"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."

"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."

"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."

"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."

"...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."

"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."

"…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."

"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."

"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."

"[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!"

"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."

"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."

"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."

"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."

"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."

"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."

"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."

"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."

"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."

"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."

"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."

"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."

"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]."

"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."

"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."

"... 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."

"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."

"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!"

"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."

"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?"