2008 USGS: Human population sky rocketing up with extinctions since 1950; extinctions now going straight up. No wonder Nazi Musk, Trump et al are wiping out DEI, research, data and protections for the species we are wiping out.

Lyle Lewis ‪@race2extinct.bsky.social‬:

Stripping “habitat loss” from species protections is extinction by policy. This rule doesn’t redefine harm—it legalizes it. Destroying habitat means destroying species.

March 2025 CO2 data released by NOAA: 428.2 ppm.

Ten years ago: 401.7 ppm.

1959: 315.98 ppm.

How soon before the orange Nazis obliterate NOAA? A year after I was born, March 1958, Dr. Charles David Keeling began regularly measuring CO2 in the atmosphere.

The good times keep on rolling … we're now at 5 consecutive days with CO2 over 430 ppm at Mauna Loa.I came to say, I must be going …gml.noaa.gov/ccgg/trends/…

— Prof. Eliot Jacobson (@climatecasino.net) 2025-04-16T13:14:49.106Z

Prof. Eliot Jacobson‪@climatecasino.net‬:

The good times keep on rolling … we’re now at 5 consecutive days with CO2 over 430 ppm at Mauna Loa.

I came to say, I must be going …

@wolverine08.bsky.social‬

Remember when 400 ppm was unthinkable…

Alert: Starving Brown Pelicans searching for food are turning up in risky places – like parking lots, backyards, Los Angeles International Airport! If you find a pelican in need, call your local animal control or our Bird HelpLine at 866-SOS-BIRD (866-767-2473) #wildliferehabilitation #BrownPelicans

— International Bird Rescue (@intbirdrescue.bsky.social) 2025-04-10T20:21:06.618Z

The Overpopulation Project

Too many people consuming too much

Overpopulation: A New Survey Confirms the Cause of the Planet’s Environmental Crises by Alon Tal, April 9, 2025, The Overpopulation Project

Synthesizing findings from hundreds of recent peer-reviewed scientific studies, a comprehensive new article reviews the effects of expanding human populations on humanity’s most pressing environmental problems.

A vast amount of research and rhetoric is devoted to the world’s many sustainability challenges. Yet most advocates and scientists assiduously avoid acknowledging the predominant driver of today’s key environmental problems: overpopulation.

Years ago, sustainable population was recognized as central to the global ecological agenda. But over time, too many green leaders became loathe to address the topic. It is rarely taught in universities. Environmental agencies remain completely obtuse. But the problem has not gone away. On the contrary, environmental damage functions are rarely linear, so the consequences of population pressures are more severe than ever.

That’s why I authored a comprehensive review of the subject in the academic journal Encyclopedia: The Environmental Impacts of Overpopulation. 

The article surveys recent scientific literature on the six most pressing environmental crises facing humanity: deforestation, climate change, biodiversity loss, fishery depletion, water scarcity, and desertification. Drawing on hundreds of peer-reviewed studies, one conclusion becomes crystal clear: unless the world confronts overpopulation, genuine environmental progress will remain elusive.

Here’s a brief summary of what emerges about each of these global challenges.

1. Deforestation: Trees Fall as Populations Rise

Global deforestation remains staggering, especially in tropical regions. Between 2001 and 2023, Brazil lost nearly 69 million hectares of forest, while Indonesia lost over 30 million. Most of this destruction wasn’t for lumber exports or furniture—it was simply to make room for 34 million and 59 million more people respectively.   

One alarming but unfortunately typical example involves the Democratic Republic of the Congo (DRC). Despite being home to one of the planet’s largest carbon sinks, the DRC has lost millions of hectares of forest in just two decades.

Why?  

Well, the country’s population doubled during this period and is now a staggering 111 million.  With only 20% of Congolese having access to electricity, an increasing number of households rely on wood for cooking and heating. Similarly, in Malawi, a 1% increase in population is associated with a 2.7% rise in deforestation.

As population swells, communities destroy their forests simply to survive.

2. Climate Change: More People, More Carbon Emissions

Every person is born with a carbon footprint. That means more people equals more greenhouse gas emissions. Even in countries with low per capita emissions,  the cumulative impact of rising populations is massive.  And it increases every day. It is no surprise that historically, global population and greenhouse gas emissions are so closely linked.

Take Israel as an example. Over the past decade, it has made impressive strides in reducing per capita emissions to meet its climate targets. But with an annual population growth of around 2%, the country’s total emissions are still set to double—even as individual emissions rates decline. Population growth steadily erases the hard-earned gains from green technologies and behavioral change.

A landmark 2017 study from the University of British Columbia building on earlier research found that having “one fewer child” was nearly 50 times more effective at reducing carbon emissions than lifestyle changes like going vegan or giving up flying.

3. Biodiversity Loss: More People – Less Nature

The World Wildlife Fund’s 2024 Living Planet Report reported a 73% decline in the earth’s monitored vertebrate populations between 1970 and 2020. The magnitude of such damage is hard to imagine. While habitat fragmentation, overhunting, and pollution are often cited as culprits, each of these pathologies ultimately is associated with population growth. 

In Madagascar, population surged from 4 million in 1950 to 32 million in 2024. During this time, the island lost about 80% of its unique forests. Species found nowhere else on Earth—including the inimitable lemurs and rare frogs—are quickly vanishing. 

Haiti tells a similar story. Its population grew from 3.2 million in 1950 to over 11 million today. Forest cover plummeted from 50% to just 1%, leading to a collapse of many endemic species.

4. Overfishing: Oceans Can No Longer Keep Up

The global appetite for fish has skyrocketed, with demand expected to double again by mid-century. Once-abundant fish stocks are now dangerously depleted: The UN reported in 2024 that the percentage of stocks fished at unsustainable levels nearly quadrupled globally during the past three decades. Yes, technology makes fishing more efficient. But the drop is largely because more people want more seafood.

In Senegal, where the population doubled from 9 million in 2000 to 18 million in 2023, overfishing has caused stocks to collapse. The Philippines offers another cautionary tale. With 55% population growth in the first quarter of the 21st century, local fisheries are under enormous pressure. In the South China Sea, stocks have declined by more than 70% since the 1960s.

5. Water Scarcity: Shrinking aquifers and thirsty cities

Global domestic water demand has increased six-fold since 1970. Much of this is driven by population growth.

Jordan offers a sobering example. With a population that increased twenty-fold since 1948, this dryland country is among the world’s most water-scarce. Urban households receive water only once a week, and farmers routinely tap illegal pipelines just to keep crops alive. The ancient Disi aquifer is being “mined “ to keep up with the country’s mounting requirements, even though its depleted ancient waters can’t be replenished. 

In India, the population has nearly tripled since 1970. Over-extraction of groundwater, especially in Punjab and Haryana, has depleted aquifers and contaminated rivers like the Ganges, threatening both agriculture and drinking water supplies.

6. Desertification: Population Growth Drives Soil Degradation

As population grows, so too does the livestock needed to feed it. Overgrazing has become a global scourge. Meanwhile, marginal lands are increasingly converted for cultivation by subsistence farmers desperate to feed growing families, leading to erosion and nutrient depletion.Over the decades I’ve lived in rural Alberta, I’ve observed human greed driven overgrazing via too many domestic animals on too small parcels of land lead to weed invasions which are fast destroying native grasslands. Cattle and horses do not eat many of the invasive weeds, which renders the weeds even more successful. Some pastures have no grasses left, just weeds that livestock do not eat, so the over grazers pay to have hay hauled in or grow hay (making more pollution) to feed their animls which the grasslands would have fed, had they not been so damned greedy.

The UN estimates that over one-third of Earth’s topsoil is already degraded. As food demand is projected to rise by 50% by 2050, the situation will almost certainly worsen. Traditional practices like fallowing (letting land rest) are no longer feasible when families constantly face food shortages. In countries like Niger and Ethiopia, land degradation is accelerating as farmers are forced to overwork depleted soils and compromise its fertility.

We Can Only Fix This By Addressing the Underlying Causes

Population growth is slowing globally—but it surely is not stopping. The world is still on track to reach 10.2 billion people by the 2080s.

The associated environmental damages are often irreversible.

Many countries, however, have made dramatic progress through voluntary, non-coercive approaches. Bangladesh, Iran, and Thailand, to name but a few, have successfully lowered fertility through education and family planning initiatives. All these countries realized that sustainability is not just about consuming less, it’s also about how many consumers there are.

With stable populations, environmental progress becomes possible.

Overpopulation remains an uncomfortable subject in most environmental circles. For decades now, many activists have avoided the issue, wary of accusations of racism or coercion.I’m constantly stunned by the venom I get when I mention human over population, and that with science and modern medicine, families do not need more than two kids. White families can produce a load of babies. I know white families with 13 kids. That’s greedier than frac’ers.It is also true that the ongoing rise in per capita consumption contributes to adverse environmental impacts.  But as my recent article confirms, the science is indisputable: demographic pressure is the primary driver of our planet’s degraded natural resources.

If we truly care about forests, fisheries, climate, biodiversity, water, and sustainable agriculture, we must speak up. Sustainable population policies must once again become a core part of global environmental discourse.

Dr. Alon Tal is a visiting professor at Stanford University and a faculty member at Tel Aviv University’s department of public policy.

15 responses to “Overpopulation: A New Survey Confirms the Cause of the Planet’s Environmental Crises”

1. Robert GillespieApril 9, 2025 at 3:32 pm This is an excellent and very depressing assessment
2. kurt klingbeilApril 9, 2025 at 3:45 pm I notice an absence of study into the effects of historical and ongoing colonial and neoFeudalist corpiratist exploitation and extraction from countries in the Global South many of which were left with massive ecological, financial, social debts which continue to be exacerbated. I see no study into the relative consumption rates between the mis-developed and developing worlds. There was one trivial reference to “going vegan or giving up flying”. Those are quaint trite trivial incrementalist semi-performative gestures which while making some contribution to GH reduction are trivial in scale compared with their current and historical consumption/ combustion rates. I see no comparative study on the accumulated per-capita emissions properly attributed to country of end use consumption – a kind of Total Cost Accounting of the effects of human assaults on the eco-systrm. In the G7 / G20 dominator cultures Maslow’s pyramid has largely been saturated and even hyper-over-saturated on the disregulated upper extremes while still actively enforcing and maintaining poverty on the bottom of the social Dis-Equality spectrum. I see no specific proposals for how _exactly_ you envision me and your readers to effect substantial pressure/advocacy on foreign population control policies / programs. In fact you appear to disparage the adoption of sensitive approaches to population control in the global south. I detect an ideological fervour which claims that population control is being overlooked / avoided while actively overlooking / evading / avoiding what are arguably far more critical factors by myopically over-focusing on pop-cont which is an inherently slow gradual process taking a couple of generations to effect significant change while our global existential predicaments and MetaCrisis intensifies continuously.Do you address these concerns anywhere in your work ? How do you propose they be addressed ? By people supporting the work of TOP directly ?
   1. Kathleene ParkerApril 9, 2025 at 4:38 pm Oh dear God.
   2. stevemckevittda604d1b36April 9, 2025 at 7:10 pm Kurt …. As others here have written, I’m dismayed by your lack of understanding regarding the dangers of this enormous crisis. Your concerns miss the point. Others here have written why. But looking at your interests: Certainly there have been (and continue to be today) terrible injustices and bad actions. These must be corrected. But right now — right now — we must drop our human population all over, involving everyone. We must lower our population. No excuses, and no exceptions. Open your thinking. Whenever I see the stuff you’re writing, my initial thought is this question: Is this person being paid by the Oil Companies? Or by Big Religion? Believing that some people have a “right” to do bad stuff (because some other people did it in the past) is crazy-time thinking. Big Oil has the money and the resources to manipulate public opinion.The more baby making, the bigger the profits and power for the rich, not just in oil and gas, also in the tech industry, and junk production. Life on earth is not just about our species, FFS.
      1. kurt klingbeilApril 9, 2025 at 11:52 pm Pfffft You have failed to address any of the points I have raised. You have failed to articulate a clear credible compelling proposal detailing how my involvement could in any way effect population policy in any of the countries specifically cherry-picked for this survey or anywhere else.You have not addressed the time taken to effect substantial changes in population demographics – unless you are perhaps advocating the deployment of Soylent Green machines…The problem stems from the PRODUCT of population and consumption Much of the Global South does not even consume/emit their “fair share” of global resources whereas in the Gx we consume/burn on average 5-6x our share with the most hyper-privedged well into the multi-thousand X.The fact that you fail to recognize that the PetroRacket funded duplicitous denialism industry has used focus on population as an evasion diversion tactic calls into question your credibility to respond at all ..Your insinuation that I could be a PetroTroll is insanely irrational. I despise the PetroRacket and want to see it rationalized nationalized and “civilized” Of course in patridiotic Amerikkka nationaliziing anything is fraught with terror – especially given the assaults by the unelected neoFeudalist clique
   3. Philip CafaroApril 10, 2025 at 4:31 pm Kurt, your wide ranging comments make two overarching points: creating just and sustainable societies must involve reducing excessive consumption among the wealthy; and it must involve radical economic reforms, including reining in the power of oil companies and other large corporations. I can’t speak for Alon Tal, but I agree with those positions. However, I don’t think any of this cancels out the equally fundamental point that the world is grossly overpopulated. The fact that this cannot be turned around quickly is not reason not to address it; the same could be said for the other underlying factors driving ecological overshoot. We are not going to turn around overconsumption or transition to less damaging technologies overnight, either. You ask what policies you might support to address overpopulation. We have a semi-comprehensive list on our website under “Solutions”: see https://overpopulation-project.com/solutions/
      1. gaiabaracettiApril 10, 2025 at 5:11 pmThe only case that I think can be made for addressing overpopulation before overconsumption (although like I said I don’t think we should be arguing about this, and we should definitely be doing both) is that population growth is not as easily reversible as economic growth, and it has a bigger built-in momentum. In other words: you could theoretically start consuming much less from one day to the next, and sometimes it happens, but you cannot or should not want to kill hundreds of millions of extra people, so once they’re born, it’s too late to do something about it. Whereas it’s not too late to reduce unnecessary travel or eat less meat or whatever.
      2. Kurt KlingbeilApril 10, 2025 at 6:50 pmI am not proposing to ignore overpopulation. It is a matter of triage and ROI.
         During Covid, there was a radical drop in air traffic, and to some extent consumption
         with immediate measureable effects…
         Similar effects occurred with the gasoline crisis in the 70’s immediate actions were taken
         to address what was triaged as a critical problem, but then immediately abandoned as the
         criticality declined.
         Preparations during WWII required massive cooperation / compliance of the public in terms
         of Victory Gardens, reduction of consumption, accommodations to shortages and LightsOut orders.Imagine attempting something like that in Amerikkka or the rest of the Gx…
         Sheer priviledged entitlement would balk at making any concessions whatsoever – insisting on their constitutionally protected uninfringed unencumbered everything.
         THAT is the area in which competent expertise and public support ought to be directed.
         Random peeps in DaWest purporting to dictate or even influence population policies in the Global South is unlikely to achieve much traction. Certainly there are already professional and amateur and other expertise working on-site in those areas
         The dominant attitude remains… “There is no problem, it certainly isn’t my problem, I insist on my entitlements, even if I were to completely slash my consumption, the over-consumption of the even-more-entitled sector and the corpirate sectors would eclipse any of my sacrifices…I saw the list and while they are all valid concerns/actions, they mostly seem like
         motherhood and apple pie stuff which do not address the magnitude of the situation.Daniel Schmachtenberger and the Consilience Project write about “seeking the third attractor”.
         Every time I encounter situation of hyper-intelligent genius types engaging in their speculative cosmology / silly-string / quantum-gravity /Mars-colonization circle-jerks…
         I think from a triage perspective that shit should be paused and that brain power and resources directed at actual urgent critical problem sets. However denialism holds sway – until the wheels really start coming off the bus
3. Kathleene ParkerApril 9, 2025 at 4:48 pmIf I had a dollar for every such similar paper I’ve read–though this one is particularly defining–I’d be rich. But, bottom line, we are even less focused on population, whether global or locally, than we were 40 years ago when (at least) media in this country and other developed nations mostly was NOT corporate owned, in this country it was regulated and REQUIRED BY LAW TO BE INCLUSIVE AND FAIR ABOUT ALL TOPICS. But in the world today (including in Europe and Asia) media are pretty much allowed to run the show as they please–and, “corporate” media “pleases” to ignore population.They put news blackout on the topic, report on population activists as people who hate babies or espouse eugenics and, certainly, never mention that the most overpopulated nations environmentally are India, China, the U.S., followed by those in Europe and much of Asia. (I remain shocked at the smugness of Americans who assume “the problem is over there” as our own nation, in many recent years, was the 6th fastest growing on Earth!)But most particularly, media deftly bury one glaring fact which every citizen of Planet Earth should understand: The planet continues to add 80 million people a year (much of it due to the lack of the AVAILABILITY OF FAMILY PLANNING in impoverished areas that most need it, so YES, LET’S FOCUS ON THOSE AREAS), with that meaning we continue to add roughly ONE BILLION PEOPLE every 12 or 13 years! The good news is that not long ago, the annual addition of people was closer to 90 million, so at least there’s progress.Again, first guilty in human over population in my view, is religion, notably those like the religions opposed to birth control, family planning and abortion, and the hideous evangelical so called Christians that are turning women and girls into baby making machines with zero rights, all in the name of the bible, god, and greed to control the vote, and next, just plain old human greed and ego (having lots of kids feeds ego and makes profits).
4. Johan LöfqvistApril 9, 2025 at 8:40 pmYes, the globe is overpopulated and we will have to fix our own food instead of imports from all the world.
   Joha Löfqvist, Swedenhttps://widgets.wp.com/likes/#blog_id=143187577&comment_id=19428&origin=overpopulation-project.com&obj_id=143187577-19428-67f8644f6d946
5. Stable GeniusApril 10, 2025 at 2:19 amThe top 20% and the top 1% are extremely happy to have hit on their Net Zero Emissions ego-trip, which gives them carte blanche to destroy the planet faster than ever before, with extra brownie points for their noble “loss and damage” reparations to the virtuous global south. The UN and EU are still pretending that Net Zero is for real, even to the extent of the EU potentially reviving global carbon offsets or carbon trading. https://carboncredits.com/international-carbon-credits-back-on-the-table-eus-climate-goal-gets-a-twist/Trump can take the US out of the Paris Agreement, but that doesn’t stop China and India from using Net Zero as a cover for their mega populations and mega coal fired power.https://widgets.wp.com/likes/#blog_id=143187577&comment_id=19430&origin=overpopulation-project.com&obj_id=143187577-19430-67f8644f6e974
   1. Philip CafaroApril 10, 2025 at 4:38 pmNet zero carbon emissions does seem highly unlikely. But even if achieved, it isn’t the same as “net zero environmental impacts.” Hence the continued relevance of human numbers.https://widgets.wp.com/likes/#blog_id=143187577&comment_id=19440&origin=overpopulation-project.com&obj_id=143187577-19440-67f8644f6fa22
      1. Kurt KlingbeilApril 10, 2025 at 6:22 pmcorrect…
         it sounds semi-plausible on the surface, but it is accounting/bean-counting trickery
         First off Net-Zero is woefully inadequate even were it achieved.
         The current GHG Overshoot is already critical.
         Net-Negative is urgently required.NetZero is Marketing/PR speak for:
         “We will continue our usual exploitive/extractive/emissive externalization of risk, cost, harm into TheCommons and beg/borrow/buy/steal accounting credits which will be deemed to reduce the NET destructive effects of our operation without us having to do anything.”
         Of course there are genuine organic small/medium efforts at mitigating their harm.
         They however produce beneficial effects which are far outstripped by the Laissez-faire bizniss-as-usual cronyCorpiratist kleptocracy.One particularly eggregious example is Biomass Carbon Credits.
         The concept of Carbon Credits has some legitimacy… It began as the pelletization of the post-clearcut-logging slash leftover by the deforestation racket. Rather than allowing the slash to rot and emit GHG, the slash would be burned, causing the GHG to be released immediately.
         This of course summarily presumes an historical credit – prior to their operation…
         CO2 was sequestered in the slash and hence deemed removed from the atmosphere.
         On a local / possibly regional scale this could have some merit. In Brrrritisch Columbia, stands of interior old-growth are being clearcut and whole trees are ground up into sawdust and then pelletized and then hauled to the coast via train and shipped through the fjords and over the ocean to soggy old England on bunker-fuelled bulk cargo ships to be burned in coal-fired power plants instead of coal.Gathering slash off the ground is relatively diffuse compared to clearcutting whole trees and pelletizing them. I wouldn’t be surprised if they decided that processing their own slash was not worth the trouble compared with grinding whole trees – and just abandoned it…
         That is what corpirations have arranged for themselves to be legally obligated to do – to maximize shareholder profit no matter what.The concept is obviously psycho-sociopathic and eco-cidal, but is treated as a legitimate source
         of Carbon Credits.
         I don’t know if any legitimate unbiased objective competent bare-metal total cost accounting has been performed on this fraud, but I have no doubt that this illegitimate yet legal process is vastly Net-Positive in GHG.https://widgets.wp.com/likes/#blog_id=143187577&comment_id=19442&origin=overpopulation-project.com&obj_id=143187577-19442-67f8644f70b0e
   2. Kurt KlingbeilApril 10, 2025 at 7:10 pmAaaaah yes…. the Cheye-Nah & India trope…
      an important yet massively neglected, evaded, denied element to this is while China and India are indeed emitting a lot of GHG, the more honest and objective perspective must take into account the _accumulated_ emissions. DaWest has been emitting for at least a century, through a couple of Industrial revolutions. It is the destabilization of atmospheric and oceanic thermodynamics due to the Global Heating due to the _accumulated_ de-sequestration – particularly post WWII when petroleum combustion exploded. During most of this period Cheye-Nah and India were still largely rural agrarian and consuming / emitting well below their per-capita share of global resourcesA proper bare-metal total cost/emissions accounting must first attribute ALL emissions and resource extractions to country of end-use consumption – not to country of production/emission. Then the properly attributed emissions must be integrated over time to arrive are total aggregated emissions. Then a further factor commonly evaded is that to obtain a proper perspective, per_capita figures must be considered. It is fashionable to jump up and down shrieking “Cheye-Nah and India” in terms of their gross current instantaneous emissions figures while ignoring the emissions used to manufacture goods imported into the west, while ignoring a lot of externalized emissions by industry and the militaries. A proper comparison requires dividing those figures by the populations to arrive at per-capita figures. The current implicit presumption is that it is sufficient to only look at national numbers and ignore the population sizes – until it comes to chastizing them for OverPopulation.
6. gaiabaracettiApril 10, 2025 at 10:31 amThis is all true, but not the whole truth. Senegal’s fisheries have become depleted by industrial trawlers from Europe, China, Russia… The Senegalese traditionally fish in small boats that catch little and don’t go very far out into the sea.As for Jordan, I’m sure you know that one of the reasons it doesn’t have much water is that Israel takes it
   https://www.newarab.com/analysis/can-jordan-ever-escape-israels-grip-water-resources
   https://theconversation.com/israel-is-hoarding-the-jordan-river-its-time-to-share-the-water-126906

The Environmental Impacts of Overpopulation by Alon Tal, April 1, 2025, Encyclopedia 2025, 5(2), 45

The Center for Democracy, Development and Rule of Law, Stanford University, Stanford, CA 94305, USA

https://doi.org/10.3390/encyclopedia5020045

Submission received: 17 January 2025 / Revised: 18 March 2025 / Accepted: 24 March 2025 / Published: 1 April 2025

Abstract

Overpopulation’s central role in environmental degradation is intermittently challenged. This article assesses the impact of mounting demographic pressures on six critical global sustainability challenges: deforestation, climate change, biodiversity loss, fishery depletion, water scarcity, and soil degradation. By synthesizing findings from hundreds of peer-reviewed studies, the article offers a comprehensive review of the effects of expanding human populations on the most pressing current environmental problems. Although the rate of population growth worldwide is slowing, human numbers are expected to continue increasing on Earth until the end of the century.

Current research confirms that overpopulation causes substantial and potentially irreversible environmental impacts that cannot be ignored if international sustainability policy is to be effective.

Keywords:

environment; overpopulation; biodiversity; climate change; soil depletion; overfishing; desertification; water scarcity; demography

1. Introduction

Unlimited growth on a planet with finite resources is impossible [1]. During the 1960s and 1970s, overpopulation was a prominent concern among environmentalists, for many, a paramount priority. Rapidly expanding global population placed unsustainable pressure on natural resources, exacerbating environmental degradation, and increasing poverty [2]. Books like Paul Ehrlich’s best-seller The Population Bomb (1968) [3] and the Limits to Growth (1972) [4] emphasized the dire consequences of unchecked population increase, prompting widespread advocacy for population control measures. In a 1971 seminal article in Science, Ehrlich along with John Holdren posited the “Impact Law”, which identified population as one of the three essential contributors to environmental impacts, along with affluence and technology [5].

More than fifty years after ecologists first highlighted the dominant role of population growth in environmental degradation, many experts continue to see overpopulation as the single greatest driver of ecological damage on Earth [6,7,8]. For instance, in a 2017 “Warning to Humanity”—cosigned by more scientists than any journal article in history—15,364 researchers cautioned that rapid population growth was a “primary driver” behind many ecological and even societal threats. They cautioned,

“By failing to adequately limit population growth… humanity is not taking the urgent steps needed to safeguard our imperiled biosphere” [9].

By the 1980s and 1990s, however, the focus of environmental organizations began to shift away from overpopulation as a central issue in the global sustainability agenda [10]. This change was driven by several factors, including criticisms that overpopulation rhetoric often targeted the Global South, unfairly blaming developing countries for global environmental harm [11]. The 1994 Cairo International Conference on Population and Development (ICPD) marked a significant turning point in the global population discourse [12]. The conference decision prioritized women’s rights, reproductive health and development [13] over explicit efforts to reduce population growth [14].

After decades of opposition to international family planning initiatives [15], the Vatican played a crucial role in shaping the outcomes of the conference, strongly resisting any language that could be interpreted as endorsing contraception, abortion or coercive population control measures [16].

The Vatican’s influence was bolstered by alliances with conservative Muslim, Catholic-majority and developing countries, who shared concerns about the ethical implications of population control policies [17]. Feminist organizations also advocated for a shift in orientation, calling for a focus on women’s empowerment, reproductive rights, and access to education and healthcare, rather than on population reduction per se [18]. The resulting retreat among many environmentalists and green NGOs from meaningful engagement with scientific studies substantiating the causal relationship between human population pressure and environmental degradation [19] proved to be enduring.

I do not like crowds or cities. The noise, fumes, pushing and shoving are assaults on my soul thus, I rarely go to towns or cities. Every time I go to Calgary, for example, perhaps once a year or every two years, to get supplies or visit friends (which I try not to do anymore to reduce my emissions), I am horrified by the exploding expansion of malls, suburbs, roads, roads, and more roads and bigger roads, all with more and more and more terribly harmful massive industrial LED lighting, on 24/7 to lure in more over consumption while wiping out migratory birds and destroying human sanity. There is no need to wonder why our species has become so fucked up. All beings need periods of darkness every night; many humans now get none. Over crowing, too much noise, too much stench. It’s impossible for me to reconcile religions pushing life, when their propaganda pushes destroying earth’s ability to sustain it. Insanity, but I think it’s again all down to profit. One way to start mitigating humanity’s over population problem is to remove tax free status for all churches, which will limit their influence and propaganda. But, tragically, extreme right gov’ts are taking over the world, and pimping forced religion on the masses, decimation of rights of women and girls all to force more babies and profits.

In 2013, British political scientist Diane Coole identified five reasons for the historic decline in advocacy for sustainable population policies and why so many environmental activists came to “disavow the population question” [20]. Among these were fatalism regarding the inevitability of demographic growth; false optimism that high birth rates would eventually resolve themselves; and skepticism about whether population growth was even a problem at all. Chief among Coole’s explanations was “population shaming”, where supporters of sustainable population strategies were accused of racism or embracing eugenics [21].

Advocates for demographic stability and sustainable population policies were aggressively assailed as not really being interested in protecting the environment, but rather disingenuously seeking to constrain reproduction amongst peoples of color [22]. For instance, when the Sierra Club debated whether to take a stronger stance on U.S. immigration in the 1990s due to its environmental ramifications, critics reproached the NGO for veering into nativist or racist territory [23]. Such hostile claims continue to the present [24]. In the face of such malicious allegations, many environmentalists lacked the resolve to stand their ground [25]. Instead, environmental organizations found it politically expedient to pivot and concentrate on the role of consumption patterns, particularly in wealthy nations, as a central driver of environmental degradation, downplaying the role of population [26].

While consistently acknowledging the important role of consumption in environmental degradation, sustainable population advocates continue to advance evidence-based arguments that most environmental problems are ultimately driven by population increase [27]. Throughout my life and now, I cannot understand how any human with access to family planning and birth control would willingly have any offspring. The horrors coming for us all no matter what our skin colour because of humanity’s greed, selfishness, over population, consumption and pollution, will be violent. Why would anyone subject their kids to a terrible and worsening future? Cruel. And, we are causing other species terrible abuses and suffering because of climate chaos and toxic chemicals in everything we eat, breath, and drink and shelter and work in. Every child born, makes that suffering worse. What type of human willingly does that to other species never mind their own kids?Using a metaphor popularized by Stanford ecology professor Paul Ehrlich, they perceive population and consumption as two sides of a rectangle: regardless of which side is longer, the total area—representing aggregate environmental damage—remains unaffected [28].

While Western environmentalism may have lowered the profile of overpopulation in the sustainability discourse, the ecological implications of demographic growth have not changed. The rate of population increase has slowed since its peak in the 1960s, but the absolute number of people on the planet continues to rise [29]. Between 2011 and 2023, human population grew by one billion in just twelve years, compared to the fifteen years it took to increase from 3 to 4 billion between 1960 and 1975 [30]. The United Nations projects that the world’s population will continue to incrementally increase, from 8.2 billion in 2024 to 10.2 billion by the mid-2080s, stabilizing around the end of the 21st century [31]. Environmental damage functions, however, are increasingly recognized as non-linear [32,33]. It is not surprising, therefore, that the magnitude of the associated adverse environmental impacts is also expected to intensify [34,35].

UN estimates, like other projections envisaging an imminent end to global population growth [36], involve many optimistic assumptions about future fertility declines in the Global South, assumptions that are challenged as excessively sanguine by many demographers [37]. Demographic models predicting stability consistently ignore waning support for family planning that threatens global fertility declines [38]. In challenging UN demographic methodology, critics chide the historic timidity of the United Nations in confronting controversial demographic issues. For instance, the UN Sustainable Development Goals do not even mention population stabilization as an explicit objective, focusing instead on other causes of environmental degradation [39].

For many countries, the local consequences of overpopulation remain too acute to ignore. With varying degrees of success, nations have implemented effective policies designed to stabilize their populations. For example, voluntary population policies in Asian countries like Singapore [40], Thailand [41], Iran [42] and Bangladesh [43] have reduced fertility levels to replacement levels or below [44]. Cognizant of past famines and concerned about the consequences of rapid population growth on societal wellbeing, from 1980 to 2016 China implemented a draconian “one-child policy” that faced widespread international condemnation for human rights violations [45]. In Sub-Saharan Africa, several countries, such as Botswana [46], Rwanda [47] and Kenya [48], have seen meaningful drops in population growth rates by improving access to contraception and encouraging smaller families [49]. Education, particularly for girls and women, is also highly correlated with lower fertility rateswhich is why religious-run gov’ts like the USA Nazis, Israel, con parties globally including in Alberta, work so hard to destroy education, notably about sex and family [50]. Greater demographic stability makes sustainability challenges more tractable.

These examples demonstrate that with sufficient political will and carefully designed interventions, rapid population growth and its environmental consequences can be mitigated. But these policy trends are hardly universal. In the absence of a global sustainable population consensus, during recent decades demographic pressures have continued to undermine environmental progress. This suggests that international initiatives must once again prioritize population stabilization to address the root causes of ecological degradation.

The present review of research published in recent years highlights the severe environmental impacts of population pressures on a broad range of media. These include six of the world’s most pressing ecological challenges: deforestation, climate change, biodiversity loss, fishery depletion, water scarcity, and soil degradation. The implication is unequivocal: meaningful ecological progress cannot be achieved without prioritizing population stability as a cornerstone of international and domestic policy.

It is duly noted that population pressures play an important role in many other local ecological challenges as well: air pollution [51,52,53], solid waste [54,55,56], noise pollution [57,58,59], inland water availability [60,61,62], water contamination [63,64,65], natural resource shortages [66,67,68], ocean acidification [69,70,71], transport of exotic animals through increased global trade [72,73,74], eutrophication [75,76] and many other environmental insults are driven by the demands of expanding human populations. Moreover, demographic pressures are directly associated with a host of other social maladies, from psychological stress [77,78,79], depression [80,81] and violence [82,83,84,85,86] to traffic congestion [87,88,89] and disease [90,91,92,93,94]. Rapid population pressures contribute to massive food insecurity [95,96], with one in eleven people globally and one in five in Africa still facing hunger [97] or routinely suffering from insufficient calories [98,99]. In most future scenarios that include population growth, food shortages are expected to remain a global scourge through 2050 [100].Light pollution is escalating rapidly, invasive and causes horrific health harms that many do not realize

Nonetheless, the six aforementioned global environmental problems on which this article focuses are unique because their association with population increase is so significant. Moreover, frequently, the damage incurred is irreversible or unlikely to be ameliorated, as long as rapid demographic growth continues.

The clear consensus emerging from current research confirms the severe environmental consequences caused by overpopulation.

2. Population Pressure’s Effect on Deforestation

Deforestation remains one of the world’s most vexing and alarming ecological challenges, inter alia because of its association with biodiversity decline [101]. Historically, deforestation has been most pronounced in regions where population pressures outpaced technological advancements in farming [102,103]. Over time, timber demand for construction, military [104], agricultural and consumer products exacerbated the phenomenon [105]. Governments have been slow to develop sustainable strategies for managing forest resources: in practice, only about 6.5% of forests worldwide are effectively protected [106], resulting in widespread land clearing. According to National Geographic, most of the Earth’ natural forests have been destroyed by human activities, leaving less than a third intact [107]. More moderate estimates suggest that about a third of the Earth’s woodlands has been lost [108,109]. Regardless of the precise figure, there is little disagreement that the phenomenon is massive and continues apace.

The international community has long recognized the gravity of the issue. In 2021, more than a hundred countries publicly proclaimed their commitment to ending deforestation by 2030 [110]. Data from recent studies, however, indicate that the phenomenon continues to grow worse. Research from the University of Maryland and the Global Forest Watch reported in 2024 that planet Earth lost roughly 37,000 square kilometers of primary forest. This represents a 3.2% increase in the magnitude of deforestation compared to the previous year. Tropical forests remain particularly vulnerable, with over 3.6 million hectares (9 million acres) of primary forest destroyed annually—an area roughly the size of Switzerland [111]. Figure 1 shows global forest loss trends over the past 22 years and the glaring failure of humanity to save the woodlands of the planet.

Figure 1. Annual global tree cover loss, 2001–2023. Source: Global Forest Watch, 2025 (https://www.globalforestwatch.org/dashboards/global/) (accessed on 23 March 2025).

It is important to distinguish between “forest loss”, which includes woodland destruction from natural causes like wildfires or pests (where regeneration often occurs), and “deforestation”, which refers to the permanent conversion of woodlands to other uses [112]. For instance, in 2022, global tree cover loss increased by 24%, primarily due to unprecedented wildfires in Canada that affected 80,000 km² of woodlands [113]. It is likely, however, that most of these forests will grow back, with natural succession processes eventually restoring the original assemblage and vegetation. Deforestation directly caused by human proliferation is fundamentally different and considered by many experts to be irreparable [114]. As tree regeneration is a slow process, once the natural vegetation is gone, this basic resource rarely returns [115]. The dramatic forest loss that has occurred during the past two decades in countries with growing populations like Indonesia (30.8 million hectares) and Brazil (68.9 million hectares) is probably irreversible [116].

Today, in many developing countries, forests continue to be cleared at alarming rates. In all of them, growing population offers the best proximate explanation for these worrying trends. But the phenomenon is also aggravated by pervasive poverty. Increased demand for food, especially in subsistence economies, drives this trend [117], creating a broader context for deforestation processes. While affluent societies consume more resources per capita than poorer ones, their demographic stability frequently enables them to avoid clearing forests for survival, with tree cover often actually increasing in developed countries [118]. Wealthier communities in developed countries also tend to have more tree cover than poorer ones [119]. Empirical evidence confirms that developed countries with stable populations have achieved greater progress in afforestation and reforestation initiatives than developing nations [120].

In contrast, population growth coupled with poverty in developing nations frequently result in unsustainable land use practices [121]. For example, a study in Malawi calculated that a 1-percent increase in population growth increases deforestation rates by 2.7 percent, due to the increased demand for agricultural land [122]. Table 1 shows a list of the countries with high rates of deforestation alongside population increase between 2001 and 2023.

Table 1. Population loss in countries with highest percentage forest loss: 2001–2022.

Forest extirpation is not only a major driver of biodiversity loss, but also increasingly recognized as a major cause of global warming. A research group at the London School of Economics estimates that “Land use change, principally deforestation, contributes 12–20% of global greenhouse gas emissions” [123]. Slash-and-burn agriculture contributes to both the continuous clearing of forest areas and carbon release [124]. At the same time, afforestation has substantial potential for boosting global mitigation efforts [125].

For many communities, especially those who suffer extreme poverty, forests, and the ecosystem services they provide, are of critical economic importance, providing up to 90 percent of local livelihoods [126,127]. Local populations rely heavily on agriculture for subsistence and economic stability [128]. As nations seek to provide food security for their growing populations, additional land is constantly required to produce the necessary calories [129]. Especially in tropical regions where the bulk of deforestation occurs, forests are cleared to create agricultural fields and residential space [130]. Subsequent to the growth of local populations, deforestation and destruction of the ecosystems upon which people have relied from time immemorial accelerate.

The association between population growth and deforestation is particularly dramatic in the Democratic Republic of the Congo. The DRC is home to the world’s fourth largest terrestrial carbon reserve [131]. During the two decades between 2000 and 2020, the country lost 15 million acres (6 million hectares) of its unique, tropical woodlands. This amounts to a full 3.6 percent of total tree cover. As expected in environmental damage functions, when a population is constantly growing, the dimensions of associated deforestation also steadily increase [132]. In recent years, total DRC forest loss has amounted to roughly 500,000 hectares (an area the size of the American state of Delaware) [133].

These alarming statistics can only be understood in the context of the extreme poverty which characterizes life for most Congolese. Its annual income of roughly 640 USD/year per capita is amongst the lowest in the world. With only 20% of Congolese citizens enjoying access to electricity, most rely on wood for cooking and heating, leading to relentless charcoal production and forest depletion [134].

The UN’s Food and Agricultural Organization has long confirmed that a high percentage of families throughout the Global South use firewood for fuel [135]. Trees allow households who lack resources to pay for electricity or fuels to stay warm and to cook. Like many other countries where poverty and population growth are positively associated, in the Congo there is no significant timber industry. Deforestation is not a function of excess resource consumption in the Global North nor the result of massive wood experts to wealthier nations. Rather, the vast majority—as much as 90%—of wood consumed is deemed “informal” [136]. Forests provide “fuel”, and the number of people in the Congo who rely on trees for domestic consumption steadily rises [137]. The increasing use of firewood for cooking and heating by expanding populations in India and Nepal has also left the region surrounding the Himalaya mountains denuded of vegetation, exacerbating erosion problems [138]. In short, economic exigencies exacerbate population-driven deforestation dynamics and accelerate forest loss [139].

Many other countries show similar dynamics. Nigeria lost 14% of its forest cover between 2001 and 2020, during which time its population almost doubled from 122 million to over 206 million [140]. A 2023 analysis in Scientific African summarized dynamics there: “The country’s population growth will also lead to increase in fuel wood demand in the rural areas…. The high reliance on fuel wood as a source of energy in the rural areas will exacerbate deforestation and depletion of carbon sink” [141].

Population pressures also drive the expansion of cities, towns and infrastructure such as highways, schools, and hospitals, with urban development often occurring at the expense of forests. In regions where rural–urban migration is widespread, sprawl often pushes into previously forested lands [142]. Even in rural areas, forests are often cleared to build new settlements and the roads that service them. Loss of woodlands typically reflects the immediate need to house more people, rather than any increase in per capita consumption levels [143]. A recent analysis suggests that between 1970 and 2010, an estimated 125,000 km² of land was converted worldwide to urban land uses. Many of these lands contained forests [144]. Land conversion rates have been particularly high in India (where population doubled from 550 million to 1.2 billion during these years) [145] and Nigeria (where population tripled from roughly 55 million people to 161 million) [146]. Land conversions explain one of the reasons why food insecurity and land degradation are associated with high population growth rates [147].

Affluence and high consumption levels surely play a role in global deforestation, indirectly, through demand for wood-related commodities. But it is the need to accommodate more people living near forests that primarily drives large-scale deforestation today. Population pressure leads to land clearance for agriculture, urban expansion, and the extraction of basic resources, making it the most immediate driver globally of deforestation hotspots. It is not just developing societies who suffer when the ecosystem services that forests provide are depleted. A study published in Nature Scientific Reports estimates that the probability that humanity will survive the present rate of deforestation without facing a catastrophic collapse is less than 10% [148]. There are few adverse environmental impacts so consistently associated with demographic growth.

3. More People, More Greenhouse Gas Emissions

The association between population growth and climate change has long been recognized [149,150,151,152]. Figure 2 shows the parallel growth in global population and greenhouse gases over the past 24 years. A growing population requires more energy for its expanded electricity, transportation, food and industrial systems. Even when individual consumption levels are low, the cumulative effect of large numbers of people using energy for heating, cooking, traveling and electricity leads to significant emissions. In many regions whose populations are rapidly increasing, fossil fuels such as coal, oil, or diesel remain the primary energy sources. Given today’s global economy, with continued reliance on these carbon-intensive sources of greenhouse gases, population growth contributes significantly to global warming, sea level rise, melting ice caps, and extreme weather events [153].

Figure 2. Association between global population growth and greenhouse gas emissions (2000–2023). Sources: UN World Population Prospects: The 2024 Revision [31]; European Commission, EDGAR Emissions Database for Global Atmospheric Research, 2025. https://edgar.jrc.ec.europa.eu/l= (accessed on 23 March 2025).

In recent years, the academic literature has been inundated with studies confirming the strong association between population growth and rising greenhouse gas emissions in developing countries. Studies in forty-four African countries [154], southern Asia [155], India [156,157], China [158] and Israel [159,160] consistently demonstrate that population increase is driving the steady rise in greenhouse gas emissions at a time when a broad international consensus calls for a 43% reduction in emissions by the year 2030 and 60% in 2035, relative to 2019 levels [161].

Every child is born with a carbon footprint—one that is perpetuated and expanded across subsequent generations. Stated simply, “more people create more greenhouse emissions”. The implications were underscored in a pivotal 2017 study evaluating the relative contribution of individual actions to climate mitigation. Wynes and Nichols calculated that having “one less child” was almost fifty times more effective in reducing individual carbon footprints than other actions such as cycling, vegetarianism, foregoing flights, clothes dryers, etc. [162]. This is particularly true today in Western societies, where per capita emissions remain high, even as present trends suggest that global emissions in many developed countries are steadily dropping [163,164].

Israel’s experience demonstrates the difficulty of meeting global mitigation targets with a rapidly growing population. In the leadup to the 2015 Paris climate accord, countries began to submit their Nationally Determined Contributions. Israel was the only OECD nation to base its emission goals on “per capita” greenhouse gas reductions. The format gave an illusion of conscientiousness. Despite achieving a reasonable drop in per capita emissions, Israel’s average annual population growth is approximately 2% [165]. Accordingly, even if it would have met its target, aggregate national carbon emissions would double over time [166]. A comprehensive 2024 analysis calculated the relative impact of different mitigation scenarios, combining technological and behavioral changes in Israeli emission reductions from electricity, transportation, water, food, construction and fuel for heat. The study concluded that “even when implementing an advanced scenario that combines major technological and behavioural changes, the nation’s mitigation goals will not be achieved given the current demographic trend” [167].How much climate chaos does Russia’s illegal invasion of Ukraine and Israel’s bombing of Palestine, Yemen, Syria, etc. and America’s huge profit-raping munitions industry supplying the bombs cause?

When the United Nations Framework Convention on Climate Change was signed in 1992, developed countries were estimated to be responsible for 75% of global emissions, while developing countries accounted for just 25% [168]. Thirty years later, significant differences persist in per capita emissions between the developing and developed countries. (For instance, according to the World Economic Forum, Africa, with 16% of the global population, is estimated to contribute only 4% of current global emissions [169].) But these asymmetrical dynamics are rapidly changing: as Western countries attempt to meet their international commitments, per capita emissions and aggregate carbon footprints are dropping in the Global North. Conversely, emissions in the Global South are rapidly increasing, indicating the start of a convergence between developing and developed countries [170,171]. Historic distinctions between wealthy and poor nations will be increasingly less salient over time.

This shift in carbon portfolios is expected to become far more dramatic over the coming decade. It is already reflected in the EU’s Energy Projections for African Countries. The assessment projects that by 2065, African countries will release 3.4 billion tons of CO₂ [172]—more than Europe does currently—and far less than the continent is expected to release forty years hence when Europe’s population may actually be smaller than its present size [173]. It is also worth noting that the carbon released as a result of deforestation in developing countries is typically underreported or, at times, not reported at all [174]. As described in the previous section, in many low- and middle-income countries, deforestation trends do not show signs of slowing down. For many developing countries, the release of the vast carbon reservoirs stored in these woodlands into the atmosphere is an order of magnitude greater than any other category of greenhouse gas emissions [175]. Yet, in calculations conducted pursuant to the Paris Climate Agreement, these are not fully calculated in national inventories [176,177].

Table 2 highlights the association between population growth and rising greenhouse gas emissions. All countries whose greenhouse gas emissions meaningfully rose between 2005 and 2023 had growing populations, most with demographic increase of over 20%. Countries whose annual emissions dropped during this period typically had stable populations and—apart from Ireland—population growth below 20%.

Table 2. % increase in GHG emissions and population growth vs. % drop in GHG emissions: 2005–2023.

More than two-thirds of the countries participating in the United Nations Framework Convention for Climate Change do not even acknowledge the role of demographic trends in their emissions profile, much less the need to consider interventions to address them [178]. As one analysis published in Science concluded, in the global climate discourse, population has been “left out in the cold” [179].

4. More People, Less Biodiversity

In 1993, 168 countries ratified a convention on biological diversity which set out to reverse the relentless extirpation of the natural world [180]. The agreement reflected growing recognition that beyond nature’s intrinsic value, it provides invaluable ecosystem services, such as crop pollination, water filtering, air purification and natural medicines [181]. Despite this international agreement, more than thirty years later, the crisis has only deepened. The World Wildlife Fund’s 2024 Living Planet Report, which tracks population changes in more than 5000 vertebrate species, reveals a staggering 73% decline in monitored wildlife population between 1970 and 2020 [182].

Presented as a sterile statistic, the drop is difficult to apprehend. A closer look at a few charismatic large mammals may be more instructive: In 2023, only 70,000 giraffes remained in the wild, a 40% decline in only three decades [183]; the world’s tiger population has dropped from 100,000 to an estimated 3500 [184]. Almost all primate populations in the wild are shrinking, with certain species, such as the cross-river gorilla, teetering on the brink of extinction, with only 200–300 surviving in the wild [185]. In nearly all cases, human encroachment and associated habitat loss are the proximate reasons for the decline [186]. For instance, the east-lowland gorilla has lost 87% of its original habitat, with its numbers dropping by 50% in recent years [187].

Population pressure manifests in a variety of ways. A high-resolution assessment of the human footprint using a 1 km² scale measured biodiversity impacts from built environments, crop lands, pasture lands, night lights, railways, major roadways, and navigable waterways. Each specific pressure was linked to threats of species endangerment identified by the International Union for Conservation of Nature (IUCN) Red List.

The study concluded that “Human impacts on threatened vertebrates are widespread, extending across 84% of Earth’s terrestrial surface” [188].

The 2019 report by the Intergovernmental Panel on Biodiversity and Ecosystem Services (IPBES) may be the most comprehensive assessment of the state of global biodiversity to date [189]. Reflecting three years of work by 145 scientists from 50 countries, the authors perused 15,000 publications and summarized the critical importance of biodiversity: 75% of agricultural production is dependent on the pollination of natural systems; 70% of cancer drugs are synthesized from natural products; 60% of carbon dioxide produced by humans is absorbed by natural systems; and 2 billion people rely on wood products for energy. The report attracted international attention for its precise estimate of the magnitude of the loss: some 25%—or 1 million—animal and plant species are at risk of extinction.

The report identifies five primary drivers of biodiversity loss: habitat destruction and fragmentation [190]; overexploitation or hunting [191]; pollution [192]; invasive species [193]; and climate change [194]. While the report suggests possible responses, such as stricter enforcement of poaching laws and better regulation of hunting protocols, it did little to draw international attention to population pressures underlying the biodiversity crisis.

The primary mechanisms of anthropogenically driven biodiversity loss involve habitat fragmentation [195]. As human populations expand, demand for land increases for agriculture, urban development, and infrastructure. This fragments once continuous habitats into smaller isolated patches, reducing their size and isolating wildlife populations, impeding species’ ability to access resources, reproduce, and migrate. Fragmented habitats are also more vulnerable to invasive species, pollution, and climate change. Research aggregating findings in five continents over 35 years showed that habitat fragmentation reduces biodiversity by as much as 75%, impairing key ecosystem functions, decreasing biomass and altering nutrient cycles. Once a habitat is divided, species loss averaged 20% after one year but exceeded 50% after a decade in the smallest, most isolated fragments [196]. According to one analysis, preventing fragmentation could avert the impending extinction of millions of species [197].

Fragmentation also disrupts ecological processes such as seed dispersal and pollination, which are vital for maintaining healthy ecosystems [198]. Moreover, smaller and more isolated populations are more prone to extinction due to inbreeding, genetic drift, and reduced adaptability to environmental changes. A recent study published in Nature Sustainability emphasized the global scale of fragmentation, linking agricultural expansion and urbanization with habitat loss, especially in biodiversity hotspots located in Southeast Asia and Central Africa. These areas, rich in endemic species, are losing their biological diversity at an alarming rate. Without comprehensive land use planning and conservation strategies, the combined effects of population pressures and habitat fragmentation could result in the loss of up to 50% of species in affected regions by the end of the century [199].

One longitudinal study in the Brazilian Amazon, conducted as part of the Biological Dynamics of Forest Fragments Project, demonstrated how fragmentation drastically reduces species richness over time. The study found that small forest fragments supported fewer species of birds, mammals, and insects (especially solitary species) than larger, continuous forests. Fragmentation’s effects are compounded by other anthropogenic threats, such as logging, hunting, and especially fire, creating an even greater peril for Amazonian biota [200].

The precise pathology of habitat destruction varies geographically, but the general dynamics are similar worldwide: As populations expand, natural habitats are cleared to make way for farmland, housing, and infrastructure. This leads to their fragmentation, and “island dynamics” where there is not enough space for organisms to survive. In densely populated regions, people rely heavily on natural resources for survival [201]. Hunting is not a “sport” but the key to survival [202]. The same is true for harvesting of timber for fuel, fish for protein, and wildlife for food or trade. These activities are driven by immediate exigencies to meet basic local necessities rather than global markets in affluent lands. In regions with rapidly growing populations, small-scale farming and hunting impacts accumulate across a large population, resulting in widespread biodiversity loss in poverty-stricken communities [203].

Countries experiencing the most acute biodiversity loss share these dynamics. As an island nation, Madagascar is home to unique ecosystems, with 90% of local species being endemic, existing nowhere else on the planet. Lemurs, tenrecs and fossas are just a few examples of charismatic local species. As the island came to be colonized, an array of large mammal species began to disappear [204]. Ecological damage became particularly acute during the past century, as population surged by 800% from 4 million in 1950 to 32 million in 2024 [205] and the country lost an estimated 80% of its natural areas [206]. A recent report about Madagascar in Science confirmed that “many species have perilously reduced population sizes”, while there may be many undocumented extinctions, especially among taxa that are poorly studied [207].

I’ve always believed parks need to be made human-free except for rangers and managers of those lands. Other species have nowhere left to go on earth, where they are not relentlessly abused, polluted, chased, tortured, and killed by humans. But again, human ego will never allow that to happen. Human ego (notably religion drive) says, it’s all about me me me me ME!

Haiti, the poorest country in the Western Hemisphere today, historically was home to one of the hemisphere’s richest ecosystems. Although data may be outdated, the country contains between 5000 and 5600 species of vascular plants, of which 37% are endemic, along with over 2000 species of fauna, 75% of which are also geographically unique [208]. Haiti’s rapidly growing population has led to devastating biodiversity loss. In 1950, the country was home to 3.2 million people and forest cover was roughly 50%. In 2023, Haiti’s population was 11.6 million, roughly 400% larger, leaving roughly 1% of original primary forest intact [209]. The need for agricultural land, combined with the reliance on wood for fuel, has led to the clearing of almost 80% of the country’s woodlands [210,211], bringing numerous species to the brink of extinction [212]. Research confirms that environmental degradation in Haiti is driven primarily by population density and lack of alternative energy sources [213].

Papua New Guinea lies on a sizable area of 462,243 km², with over 20,000 km of coastline. Its extraordinary biodiversity is attributed to abundant water resources (more than 5000 lakes) and one of the world’s largest mangrove systems with 8000 km of wetlands, lagoons, coral reefs and atolls, along with 100 offshore islands [214]. With over 28 million hectares of tropical rainforests, it hosts the third largest rainforest in the world, which, due to its relative isolation and high altitude, is considered a biodiversity treasure [215]. As a result, Papua New Guinea is home to one of the richest assemblages of vertebrates on Earth. Its forests harbor at least 1786 species of birds, mammals (including 10 of the world’s 12 species of tree kangaroos), reptiles, and amphibians. This is estimated to be over 5 percent of the world’s total biodiversity—with many species yet undiscovered and unclassified.

The country’s unique biodiversity, however, is in “freefall”. A 2022 summary by the United Nations reports that 66% of populations of known animal species in the country are decreasing, with 623 plants and 481 animals currently listed as either critically endangered, endangered or vulnerable. A fifth of local mammal species are defined as threatened [216]. Again, the underlying driver of this loss is the exponential growth in humans [217,218].

In 2024, Papua New Guinea’s population was roughly 10.5 million people, roughly seven times the 1.5 million counted in the 1950 census [219]. The country’s forests face mounting pressures by the growing number of people, enlarging agroforestry-related land clearing, mining and logging activities, along with expanded subsistence agriculture [220]. In a 2013 report by the Papua New Guinea National Research Institute, the government was forthright about these dynamics and what should be done:

“The government of Papua New Guinea has recognised that the population growth rate and distribution of PNG’s population has become more unsustainable. With the population doubling approximately every 27 years, pressure on the available natural and human resources continue to increase dramatically as well as the need for increased demographic investment and service delivery. This is considered a major stumbling block for the achievement of responsible sustainable development.” [221]

In a recent retrospective evaluation, the British Royal Society estimated that between 1996 and 2008, 60% of total global biodiversity loss for bird and mammal species occurred in just seven countries, Indonesia, Malaysia, Papua New Guinea, China, India, Australia and the USA, where the majority has occurred on the islands of Hawaii [222]. Table 3 shows the population growth in these countries during those 12 years. As habitat decline and biodiversity loss is a prolonged process, population increase during the 22 years between 1986 and 2008 was also calculated. The majority of biodiversity loss on Earth has occurred in countries experiencing exceptionally rapid population growth, with average annual increases ranging from 1.3% to 4%.

Table 3. Population increase in countries where most biodiversity loss occurred: 1986/1996 to 2008.

By contrast, the Nature Conservation Index ranks the effectiveness of countries in protecting the natural environment [223]. Economic capacity is not a particularly good predictor of high performance. Of the top-twenty ranked countries, seven are developing countries (four are in Africa), with per capita GDP below USD 10,000. While conservation policies are critical for success, so is population stability: women living in all of the “conservation champions” have total fertility rates below three children per family, and with the exception of Australia, all are trending towards demographic sustainability.

5. Overpopulation and Overfishing

Overfishing refers to the practice of harvesting fish from oceans, rivers, and lakes at rates that surpass their natural replenishment levels. Because more fish are caught than are replaced through natural reproduction, fish populations around the world are plummeting [224]. With the number of people in the world growing and demand for fish doubling by mid-century [225], critical thresholds are being crossed. What emerges is a clear causal relationship between the rise in human populations and the decline in fish populations [226].

Unsustainable extraction not only threatens marine ecosystems, but could ultimately lead to the eventual collapse of entire fisheries [227].

The world’s natural marine environments serve as a quintessential, overexploited “commons”, described in Garret Hardin’s seminal 1968 essay, The Tragedy of the Commons. Hardin identified fisheries as particularly susceptible to overexploitation in a world where human population is expanding: “Maritime nations still respond automatically to the shibboleth of the “freedom of the seas”. Professing to believe in the “inexhaustible resources of the oceans”, they bring species after species of fish and whales closer to extinction” [228].

Since this warning was published, fish stock depletion has escalated drastically, driven by global population growth and the associated increased demand for animal-sourced, protein-rich food [229]. The expansion of industrial fishing fleets, equipped with advanced technologies such as deep-sea trawling, GPS tracking, and fish aggregation devices (FADs), has further contributed to overfishing [230]. Dramatic declines in large predatory fish, like tuna and cod [231], offer indicators of broader ecosystem destabilization [232].

Overfishing is evaluated using benchmarks established by international and regional bodies which categorize fish stocks as underfished, maximally sustainably fished, or overfished [233]. One widely used metric is Maximum Sustainable Yield (MSY), representing the highest quantity of fish that can be harvested annually indefinitely without depleting the stock. Other indicators, such as spawning biomass and fishing mortality rates, provide evidence-based insights into stock health [234]. Standards are set, like those established under the Marine Stewardship Council certification program, adding a layer of scrutiny, and promoting accountability within the global fishing industry [235]. These benchmarks and certifications are valuable for monitoring but, in practice, have not been able to stem the negative global trends driven by human population pressures. Rather, they allow for higher resolution when reporting fishery declines.

The United Nations’ Food and Agriculture Organization monitors global fish stocks and its data reflect the magnitude of the ongoing collapse. According to the organization’s official figures, in 1960, when there were 3 billion people on planet Earth, roughly 10% of the world’s natural fish stocks were classified as overfished; by 2019, with a global population of 7.7 billion, this percentage tripled to roughly 34%. Figure 3 offers a graphic presentation of the steadily decline. The FAO’s 2022 report reveals that “maximally fished stocks now account for 57.3 percent of total stocks, while underfished stocks, a mere 7.2 percent” [236].

Figure 3. Fraction of fishery stocks within biologically sustainable levels that have decreased (1974–2019). Source: UN, Food and Agriculture Organization, State of the World’s Fisheries and Aquaculture 2022.

These figures often rely on national reporting, which for a variety of reasons, historically, has been prone to significant underestimations [237]. This produces a phenomenon known as “phantom recoveries”, where fish stock are actually in decline and overfished, but misinformed fishery managers continue to maintain current fishing quotas or even expand catch levels [238]. If current trends persist, remaining fish populations in the oceans may experience irreversible declines, posing a severe threat to global food security, especially in developing countries [239].

Freshwater systems, which comprise only 0.01% of global water resources and 0.8% of the Earth’s surface, are even more vulnerable than oceans to overfishing due to their limited size and capacity [240]. Lakes and rivers are more constrained in their capacity to support large-scale fish populations, making them highly susceptible to overfishing, pollution, habitat destruction, and water diversion. These systems, which support roughly 1 million species—6% of known life forms—have seen dramatic population declines [241]. Between 1970 and 2014, freshwater fish populations declined by 83%, a rate surpassing that of marine systems [242].Just wait until frac’ers suck lakes, creeks and rivers dry, injecting the water with much of it lost permanently to the hydrogeological cycle.

Population growth, particularly in coastal regions, has significantly intensified pressure on global fish stocks. Regions such as Southeast Asia [243], the Mediterranean and Black Seas [244], and much of West Africa [245], where fishing remains a major economic activity, have witnessed particularly severe declines in fish populations. The combination of rising human demand for protein and modern technologies have intensified fishery-related conflicts and led to more aggressive, destructive fishing practices [246]. A range of 17 anthropogenically associated stressors affect both the quantity and quality of wild-caught and farmed fish (“blue foods”) [247], highlighting the cumulative pressure facing coastal communities worldwide [248].

The Philippines, for example, an archipelagic nation with a population of over 100 million, exemplifies how rapid population growth exacerbates overfishing. Coastal regions in the Philippines that are heavily reliant on fish for sustenance are struggling to cope with a 55% growth in population during the first quarter of the twenty-first century [249]. Provincial data reveal the adverse effects on fishermen’s livelihoods as fisheries steadily decline [250]. In regions like the South China Sea and the Philippine Sea, fish stocks have dropped by more than 70% since the 1960s due to unsustainable practices like “fishing down the food web”, where smaller fish, lower in the food chain, are targeted after larger species become depleted [251,252].

International interventions, such as stricter trawling regulations, have attracted attention in recent years [253], but their effectiveness in maintaining stability have thus far been underwhelming [254]. The vast majority of global fish stocks that have been assessed need rebuilding, with significantly reduced exploitation required to reverse the collapse of vulnerable species [255]. Marine reserves, offering sanctuaries for fish populations, have been hindered by enforcement challenges and economic dependence on fishing [256]. A vicious cycle ensues where, in the absence of abundance, local fishing industries adopt destructive practices like blast and cyanide fishing, alongside aggressive trawling, that further degrade marine habitats, making recovery difficult [257].

Peru, one of the world’s leading fishmeal producers, also faces a severe overfishing crisis, largely due to the increasing global demand for its anchoveta stocks [258]. Anchoveta, a small pelagic fish, forms the backbone of Peru’s fishery sector, and is used primarily in fishmeal production to support livestock and aquaculture [259]. Since 1980, the country’s human population has doubled, leading to overfishing that caused anchoveta stocks to decline by more than 50% between 2000 and 2020 [260]. Recently, fishing activity in these coastal areas has in fact dropped off, after the remaining adult anchoveta populations dwindled below economically viable levels [261].

Senegal is just one of many African countries that has experienced dramatic declines in fish stocks [262] as the local human population doubled from 9 million in 2000 to 18 million in 2023 [263]. The implications are profound in a country where fish and seafood represent more than 40% of the animal protein intake and where one in six people work in the fisheries sector [264]. Long-term trends in the trophic level of exploited species and total catches are discouraging, reflecting mounting human pressures and increased fish catches. This pressure is particularly manifested at the top of the food web, suggesting that “fishing down the food web” is quite advanced in the country’s marine ecosystems, with white grouper, an especially popular local catch [265], virtually disappearing [266]. Results of stock assessments suggest a 63% reduction in Senegal fish populations compared to their pristine state [267]. The collapse is driven by a growing local demand along with competition from foreign fishing fleets [268]. Senegal’s local fishing communities have been hit hardest by the depleted stocks, with the volume of catches by traditional wooden fishing canoes falling 58 percent in just a decade. Artisanal fishermen find it increasingly challenging to sustain their livelihoods [269]. To survive, desperate Senegalese fishermen often cross illegally into Mauritania, sparking tensions and a harsh enforcement response by the Mauritanian coastguard that has led to fatal incidents [270]. Ineffective local monitoring and enforcement against illegal, unreported, and unregulated fishing further strains depleted marine resources [271].

Aquaculture offers a partial solution by supplementing natural marine supplies, but it introduces its own environmental consequences [272]. The overfishing crisis ultimately stems from an imbalance between supply and demand. A 2024 review in Science outlines key measures for reversing these trends: allowing fish to grow and reproduce before capture, using environmentally low-impact fishing gear, establishing no-take zones to preserve genetic diversity, and maintaining functional food webs by reducing fishing of forage species like anchovies, sardines, herring, and crustaceans like krill. The strategy is grounded on a simple yet vital principle: “take out less than is regrown” [273]. But such measures are difficult to implement when growing populations rely on local fisheries as a primary source of food [274].

6. The Population Threat to Global Water Security

Water scarcity is intrinsically associated with population growth, as expanding human populations require more water for drinking, agriculture, industry, and sanitation [275]. Globally, water demand has surged due to urban expansion, industrialization, and intensified agricultural production to meet the food needs of larger populations [276].

With human numbers doubling on Earth between 1970 and 2020, demand for freshwater resources for domestic use increased globally by 600% [277].

Human stupidity check:

2012: AEA: Support to the identification of potential risks for the environment and human health arising from hydrocarbons operations involving hydraulic fracturing in Europe

… A proportion (25% to 100%) of the water used in hydraulic fracturing is not recovered, and consequently this water is lost permanently to re-use, which differs from some other water uses in which water can be recovered and processed for re-use. …

This impact on the drinking water system can lead to the need for engineering solutions for reduced aquifer levels – for example lowering of pumps or deepening of wells…. Further consequences of reduced water levels mentioned include:
• The potential for chemical changes to aquifer water, including altered salinity, as a result of the exposure of naturally occurring minerals to an oxygen rich environment.
• stimulated bacterial growth, causing taste and odour problems in drinking water.
• upwelling of lower quality water or other substances (e.g. methane – shallow deposits) from deeper and subsidence or destabilization of geology
…
Re-fracturing may be needed during the production phase. It is estimated that re-fracturing may take place up to four times from an individual well,….

2023: Monster Fracs, getting bigger and thirstier, threatening America’s drinking water aquifers

End human stupidity check.

In the mid-1980s, Malin Falkenmark, serving as the State Hydrologist for the Swedish Meteorological and Hydrological Institute [278], developed objective standards for managing water scarcity [279]. In an influential article with colleagues, she introduced the Water Stress Index, which established a simple framework that has since been widely accepted [280]. The standard defines water scarcity based on water availability per individual, setting the baseline at 100 L per person per day.

To understand a country’s overall hydrological capacity, the standard is typically aggregated to a national scale. A country with less than 1700 m³ of water per capita annually is considered “water-stressed”; below 1000 m³, the country experiences “water scarcity”; and below 500 m³, it faces “absolute water scarcity” [281]. Falkenmark’s equation uses human population as a denominator.

This underscores the central role of population size in characterizing scarcity: water stress is defined simply as too large a population per unit of water available from the water cycle.

The United Nations Food and Agriculture Organization reports that water resources in most places in the world are under increasing stress. Population growth is identified as the primary driver, followed by rising incomes and changing lifestyles and diets [282]. According to a 2023 World Resource Institute Assessment, the most vulnerable regions are the Middle East and North Africa, where 83% of the population is exposed to extremely high water stress [283]. Historically, the region has seen a dramatic demographic increase. The resulting hydrological pressure has even led to political unrest and violent protests by citizens dissatisfied with government policies amid worsening water shortages [284]. Syria is a conspicuous example of a Middle Eastern country where water stress led to widespread agricultural failure with disastrous results [285].And genocidal Israel is stealing billions of dollars of Paletinians’ oil and gas which must be frac’d requiring masses of water permanently lost to the hydrogeolocial cycle. In 2024, Israel already granted licences to numerous companies to extract resources that do not belong to Israel.

Groundwater resources, which recharge slowly, are particularly vulnerable to over-extraction [286]. It is increasingly common for countries facing hydrological shortfalls to rapidly withdraw water from aquifers that took millennia to accumulate. In the long run, such “overdrafts” are unsustainable. Hydrological deficits are occurring all over the world, with the demand for water outpacing the natural replenishment rates of freshwater resources. Lake Chad offers a cautionary tale: During the 1960s, it ranked as the world’s sixth largest inland water body (with an area of 25,000 km²). With the doubling of population in its riparian states (Cameroon, Chad, Niger and Nigeria), the lake shrank to less than 2000 km² by the 1980s, losing more than 90% its original area [287]. A recent evaluation of Lake Chad’s condition published in Scientific Reports ends with the warning that the modest water remaining is threatened due to “increasing pressure on resources in consequence of rapid population growth in Sahel” [288].

My well water after Encana/Ovintiv illegally frac’d the aquifers that supply my community. Bathing in this water painfully burned skin. My well was the best producer in the valley – destroyed by greed, arrogance, callous idiocy. Historic records stated “Gas Preseent: No.” I grieve the loss of my water every day; it’s been 21 years since it got frac’d.

India exemplifies the challenges posed by water scarcity in a densely populated country. As the population has grown from 500 million in 1970 to over 1.4 billion in 2023, predictably, demand for water has intensified. Agriculture consumes roughly 85% of India’s freshwater resources, and shortages in the rural regions have become acute [289]. Overextraction and anthropogenic activities taking place alongside dense population centers have caused contamination and overutilization of key rivers, including the sacred Ganges [290]. At the same time, groundwater levels in regions like Punjab and Haryana are critically low due to over-pumping for irrigation [291]. With 18 percent of the world’s population, but only 4 percent of Earth’s water resources, the World Bank warns that India’s perennial water shortages will soon grow more severe [292]. Already, over 600 million people in India experience high to extreme water stress [293]. While the 1960 Indus Water Treaty between India and Pakistan has helped avert violent conflict over the shared water resources until now, there are cases where water shortages become a source of conflict.

One often-cited example involves Syria: demographically driven water scarcity there has been a significant factor in its political instability. Since receiving independence until the advent of its recent civil war, Syria’s population grew by roughly 700%, from 3.2 million in 1946 to 22.7 million people in 2011 [294]. This dramatically reduced per capita renewable water availability [295], from an abundant 5500 m³ level in the mid-twentieth century to below 700 m³ per person, a level at which local communities are considered water-stressed [296]. Depletion of groundwater resources and salinization of farmlands were already identified as a critical issues before the unprecedented 2007 drought and subsequent dry years [297].

While multiple factors contributed to the Syrian Civil War, many analyses emphasize successive years of droughts that led to the collapse of local agriculture, forcing migration to urban areas and ultimately leading to inter-ethnic violence [298,299]. Other explanations highlight Turkey’s unilateral diversion of Euphrates water [300] or inherent vulnerabilities in Syria’s disparate agricultural systems [301]. Typically, there are many forces at play beyond natural resource shortages that contribute to extreme social instability and warfare. Though hostilities are rarely attributable to a single factor, rapid population growth and demographic pressures significantly undermined Syria’s water and agricultural resilience, accelerating the social collapse that ultimately led to civil war [302].

Neighboring Jordan’s population increased twenty-fold during the past 75 years from 500,000 in 1948 to 11.5 million in 2023 [303], making it amongst the most water-scarce countries in the world [304]. The government reports that per capita renewable freshwater availability is just 61 m³ annually—only 12% of the minimum threshold set by the Falkenmark Index. The arrival of 1 million Syrian refugees after 2011 further strained resources, contributing to a 40% increase in water demand [305]. Refugees are particularly vulnerable to water scarcity, with the United Nations reporting Jordanian camps facing severe shortages, with inadequate access to basic sanitation and hygiene infrastructure affecting children’s ability to attend school [306].

In practice, Jordan’s acute water shortages translate into highly intermittent water supply to urban residents. Residents of major cities receive water once a week or once every other week [307], relying heavily on rooftop cisterns to store water for basic needs [308]. In rural regions, farmers report only receiving 60% of their expected allocations, leading to rampant water theft and illegal pipeline tapping, as desperate farmers seek to avoid losing their crops [309].

Since 2013, Jordan has begun to mine the ancient waters of the Disi aquifer, which lies 500 m underground near the Saudi Arabia border [310]. Formed roughly 30,000 years ago, this fossil aquifer cannot be replenished. Recent research confirms projections that the resource will either run dry [311] or become too saline to use within a few decades [312]. Agreements with Israel, which has developed a substantial desalination infrastructure [313], may temporarily ease urban water shortages. But Jordan’s rapid population growth and naturally arid conditions suggest that its traditional agrarian economy is not sustainable.

Egypt, once a water-rich nation, now faces severe water scarcity driven by its explosive population growth. Historically reliant on the Nile River for its freshwater, as recently as the 1960s, Egypt enjoyed a water surplus of 20 km³ per year. With its population more than tripling from 30 million in 1960 to 112 million in 2023, Egypt now faces a water deficit of 40 km³ per year. The country must supply water to an additional 2 million people each year, forcing it to import more than 50% of its food and become the world’s largest wheat importer [314]. With a projected population of over 157 million people by 2050 [315], rapid population growth will continue to transform the country from a water superpower to a water pauper.

Natural water resources are shrinking at an alarming rate in the face of mounting demand, with scarcity expected to intensify globally, especially in regions with rapidly growing populations [316]. Climate change is expected to further exacerbate water scarcity by altering precipitation patterns and increasing the frequency and severity of droughts [317]. The World Population Review ranks the most water-stressed countries each year. Table 4 lists the ten most “water scarce” countries in 2024. All showed substantial population growth during the past twenty years.

Table 4. Population growth in the world’s ten most water-scarce countries.

By 2050, more than half of the world’s population will live in water-stressed regions, with sub-Saharan Africa, the Middle East, and parts of South Asia facing the most acute shortages [318]. To meet the projected rise in demand for food, fiber and biofuels, agricultural production will need to increase by 50% relative to 2012 [319]. The anticipated increase in human population will push water demand to unprecedented levels, with almost half of humanity by mid-century expected to face acute shortages as an existential challenge [320].

7. Proliferating Populations, Land Degradation and Desertification

Land degradation refers to the decline in the productive capacity of land and the diminution of its productive potential and value as an economic resource [321]. Contrary to common misconceptions, desertification is not the natural expansion of existing deserts. While there have been innumerable definitions given over the years to the phenomenon, it generally refers to the degradation of land in arid, semi-arid, and dry sub-humid areas [322] where desiccated conditions and extreme temperatures make soil restoration far more challenging than in more temperate climates [323]. Soil erosion, a more generic process, entails accelerated removal of topsoil from land surfaces through water, wind and human activities [324], reducing the land’s ability to sustain crops or vegetation [325]. Both land degradation and desertification are highly associated with increased pressures from populations [326].

Throughout history, land stewardship has been guided by the recognition of carrying capacity and the perils of exceeding natural biological thresholds. Ancient civilizations were quick to observe the detrimental effects of soil fertility loss, caused by the conversion of natural ecosystems into croplands or rangelands [327]. The book of Genesis even describes the dynamics of resource overshoot when the herders who tended the flocks of the Patriarch Abraham quarreled with those of his nephew because “the land could not support them while they stayed together, for their possessions were so great that they were not able to stay together” [328].

The effects of human activities are particularly acute in drylands where people depend heavily on local ecosystems for basic needs [329]. As population pressure begins to physically erode drylands, local ecosystem services, such as food, firewood, forage, fuel, building materials, and water for humans and their livestock, deteriorate. Resulting damage can become irreversible, as soil fertility and ecosystem function are difficult, if not impossible, to restore [330]. Where efforts are made to rehabilitate degraded land, they often require substantial time and resources, with decades passing before even partial recovery of productivity is achieved—if it is achieved at all [331].

In 2005, 1300 experts joined under the auspices of the United Nations to prepare the Millenium Ecosystem Assessment, which examined the state of the planet and its disparate ecological regions. The report identified desertification as the environmental problem affecting more people than any other single ecological challenge. It estimated that the livelihoods of over 1 billion people across 100 countries were threatened by desertification, with nearly 1 billion of the poorest and most marginalized people living on the most vulnerable lands at risk [332]. Since the publication of this seminal report, the population of drylands has increased and the crisis has only worsened. Recent calculations by the United Nations indicate that at least 100 million hectares (240 million acres) of healthy land is “lost” each year to the forces of desertification [333].

The cumulative impact is staggering: desertification adversely affects 36 million square kilometers of land [334]. Present estimates suggest that 500 million people already live in areas that suffer from desertification [335]. The livelihoods of twice that number are threatened by the scourge of land degradation [336].

While specific dynamics vary by region, the general pattern of events leading to land degradation is well documented: as population pressure grows, human activities adversely affecting land productivity intensify [337]. The specific drivers of land degradation and desertification are of course diverse, including overgrazing, deforestation, destructive cultivation and ill-advised irrigation practices [338]. But for the most part, they all emerge after a general succession of events transpires. Populations grow, human demands exceed the land’s carrying capacity, and inappropriate management of land resources ensues. Over time, fertile areas become barren, leaving the soil depleted and desert-like, incapable of sustaining life [339].

Overpopulation creates a feedback loop that accelerates land degradation and desertification by intensifying demand for food, water, and living space, pushing human activities beyond traditional arable areas. As the number of people reliant on subsistence and pastoral agricultural systems increases, more and more land is cleared for agriculture and habitation, often resulting in unsustainable farming practices that accelerate soil depletion and erosion. A vicious cycle is created where population pressure pushes productive grasslands beyond their capacity. When they can no longer provide adequate forage for herds, pastoralists move on, utilizing marginal lands which become degraded at an even faster rate [340]. Inappropriate farming techniques, including monocropping and the excessive use of chemical fertilizers, are also associated with rapidly expanding populations, degrading soil structure and biodiversity while further accelerating desertification. Deforestation, another consequence of rising population pressures, exposes soil to wind and water erosion by removing root systems that stabilize land, diminishing the soil’s ability to retain moisture. In arid lands, salinization caused by excessive irrigation on arid lands further compounds these effects by leaving salt deposition that reduces soil fertility [341]. Each of these drivers is intensified by population growth, as rising resource exploitation perpetuates more unsustainable practices, accelerating land degradation and desertification.

Overgrazing is frequently cited as the leading cause of desertification worldwide [342]. Typically, the phenomenon begins with an increase in the number of humans relying on foraging animals for their livelihoods. To support larger herds for meat and dairy production, livestock numbers eventually surpass the carrying capacity of traditional rangelands. The excessive foraging depletes vegetation cover, exposing soil to wind and water erosion. The removal of plant roots reduces soil cohesion, leading to the loss of topsoil, which is vital for retaining nutrients and moisture [343]. Heavy grazing also compacts the soil, reducing its organic carbon, nitrate levels, and moisture [344], further diminishing the land’s ability to support vegetation.

The Tragedy of the Commons paradigm, originally introduced in 1968, describes the dynamics that drive the unsustainable exploitation of shared pasturelands. Mounting population pressure on unregulated commons leads to system collapse [345]. Even after decades of regulation and stock limits, these forces persist [346]. For example, recent studies in Mongolia suggest that herders are aware of the risks of overgrazing. Yet they choose to prioritize short-term economic benefits to sustain growing populations, triggering overexploitation of commonly owned lands. Government policies intending to reach a forage–livestock balance are widely ignored [347]. Over time, overgrazing leads to irreversible damage to the soil [348].

These dynamics are unfolding around the world. In Niger, for example, rapid population growth has exerted enormous pressure on land resources [349]. Over the past 50 years, the population has increased by 500%, from 5 million in 1974 to 27 million in 2023. This growth has caused the degradation of over 60% of arable land, primarily due to overgrazing and deforestation [350]. Smallholder farmers, with few alternatives, are forced to continuously farm and graze on the same land, leading to steady declines in soil fertility [351]. The need for firewood and more arable land has exacerbated deforestation, leaving soil bare and vulnerable to wind erosion, particularly in the arid Sahelian climate where rainfall is modest and unpredictable [352]. Studies report that Niger loses approximately 100,000 hectares of arable land annually to desertification, a trend that threatens both food security and the livelihoods of its population [353].

As populations continue to grow, competition for limited land resources intensifies, leading to shorter fallow periods and increasingly unsustainable agricultural practices [354]. Land that once had the opportunity to recover between cultivation cycles is now farmed continuously, depleting its nutrients and compromising its structure. The expansion of agricultural land into previously forested areas, as described, results in significant deforestation, further exacerbating soil erosion and the loss of biodiversity, which could play an important role in soil replenishment [355]. More than economic development, population growth remains a dominant driver of urban sprawl that encroaches on arable terrain, reducing the amount of productive land available per capita and leading to problems of employment, feeding the urban population and environmental protection [356].

This escalating cycle of land degradation due to population pressures has caused the Earth to lose approximately one-third of its arable land over the past forty years [357].

8. Conclusions

This review summarizes the effect of population pressures on the critical sustainability challenges facing humanity. It suggests that the resulting irreversible damages to disparate ecosystem services are already well underway. Rising standards of living and consumption patterns surely contribute to the magnitude of the impact. But the rapid growth in human population serves as the ultimate driver of a wide array of harmful environmental impacts. In theory, advancements in clean technologies, efficient land management, desalination and sustainable fishing practices could do much to ameliorate adverse outcomes. Present experience, however, indicates that resources for such interventions will not be mobilized. In the face of mounting population pressures, deforestation, biodiversity loss, climate change, overfishing, water scarcity and land degradation will continue to intensify.

The most optimistic estimates published by the United Nations suggest that the world’s population will exceed 10 billion people by the end of the 21st century—an increase of roughly 4 billion from the start of the century. Yet the UN demographic model has a range of possible trajectories, including scenarios where the global population grows by an additional 2 billion, making Earth 20% more crowded than commonly accepted projections [358]. Many experts argue that higher population scenarios are in fact far more plausible, if present policies and attitudes remain unchanged [359].

In a world where ecological and climatic systems exhibit non-linear patterns of damage, the consequences of continual environmental disruption are inherently unpredictable [360,361,362]. The environmental implications of an additional two billion (or four billion) people on the planet are difficult to predict precisely, but the results ecologically will not be favorable. Tipping points will be crossed where climate change becomes catastrophic, ocean acidification decimates marine systems, terrestrial species extinction accelerates, fisheries collapse and land productivity loss becomes irreversible.

At a more micro level, countries with rapidly growing populations will suffer increasingly acute symptoms, undermining local or national efforts to confront environmental hazards like solid waste [363] or air pollution emergencies [364]. While these might not be characterized as part of a “global crisis”, they often pose the most egregious public health insults and immediate challenges for humans at the local level. Rapid population growth also exacerbates social pathologies such as traffic congestion, overcrowded classrooms, courtrooms and hospitals, or even rising violence [365]. Making progress on most of these issues will be extremely challenging as long as rapid population growth continues. The metaphor of a treadmill—where efforts to move forward prove futile against the relentless growth of carbon, water, and land footprints—is frequently invoked, and not without good reason [366].

This article’s focus on the effect of population increase in no way contests the significant contribution that aggregate consumption makes to global ecological decline and climatic disruption [367,368]. Individual and collective ecological footprints, especially in affluent countries, must be dramatically reduced. But dismissing the critical role of overpopulation growth in accelerating global environmental deterioration or evading the issue entirely because it is sensitive or intractable weakens the global response to the most pressing environmental challenges.

There are, of course, many actions that can be taken and many policies that can be adopted to ameliorate the six environmental problems summarized in this article. These include expanding global afforestation efforts [369,370] and the electrification of communities that rely on trees for fuel [371,372]; expediting the transition to a low-carbon economy [373] and adopting a global price for carbon [374,375]; dramatically expanding strategically located nature reserves worldwide [376,377] and creating ecological corridors [378,379]; intensifying aquaculture [380] and strengthening fishery management [381]; increasing sea water desalination [382,383] and wastewater reuse [384,385,386]; and implementing a range of sustainable agriculture practices and soil conservation measures [387,388]. Assessing the potential effectiveness of these interventions and challenges to implementation is a formidable task and beyond the scope of this article.

It is important to note though that the above strategies share a common weakness, they address “direct drivers” or “symptoms” produced by these disparate environmental crises rather than their underlying sources. Addressing the underlying root causes or “indirect drivers” is critical and requires family planning programs and policies—such as those briefly described and documented in first part of this article—that encourage lower fertility. If rapid population growth continues, the ultimate outcomes of most proposed solutions to myriad environmental crises will likely be unsatisfactory.

The UN 2024 World Fertility Report calculates that women today bear on average one child fewer than they did around 1990 [389]. This constitutes an encouraging trend. In some countries, this reflects evolving social dynamics. In many others, however, it is the result of deliberate public policies, robust family planning initiatives and an honest reckoning about the catastrophic implications of unchecked population growth. These efforts have transformed national demographic profiles in disparate places, offering a modicum of stability that now enables meaningful economic and environmental progress [390]. A consensus, acknowledging the central role of population growth in causing the world’s most pressing environmental problems, is a critical starting point. Without addressing this issue, progress towards sustainability will remain elusive and humanity’s ability to confront its most urgent ecological crises will continue to falter.

Funding

This research received no external funding.

Data Availability Statement

The data displayed in this article was collected by research and reports generated by public agencies and are available in the internet, as indicated in the delineation of sources.

Refer also to:

2013: Science be damned, EnCana wants to inject toxic waste into drinking water aquifer

2014: Fracking in Water-Stressed Zones Increases Risks to Communities – and Energy Producers

2017: Alberta issues 40 water shortage advisories while continuing to let frackers inject hundreds of millions of gallons fresh water losing much of it from hydrogeological cycle forever. Worse, Notley Govt is subsidizing frac industry’s water abuses while making frac contaminated families live without safe water

1981: Bestiaire 24e by Quebec painter Alfred Pellan

2023: South Africa to frac ecologically sensitive water scarce Karoo. Frac’ing will “directly and detrimentally affect women’s lives.” Yup.

2024: Like frac’ers, AI devours fresh water and is grossly energy intensive and polluting.

2025: Art Berman on collapse of humanity.

… We’re not the first to face collapse—just the first to pretend it isn’t happening. Hine’s message is clear but unsentimental: the question isn’t how to solve everything, but how to live through what’s coming. … I don’t believe humans (and many other species) will survive what our pollution, greed, laziness, selfishness, arrogance, frac’ing, insatiable lust to exploit and rape earth and others, and toxic chemicals rage upon us. Nothing spiritual will change the evil beast of human nature; religions will prevent that.

2025: Amazon, Google, & Microsoft allegedly operating and expanding water-intensive datacentres in some of the world’s driest region

2025:

March 2025 CO2 data released by NOAA: 428.2 ppm.

Ten years ago: 401.7 ppm.

1959: 315.98 ppm.

I avoid flying (it broke my heart when communities far away begged me to come help protect their health and drinking water from frac invasions requiring me to fly – I will never fly again); limit my driving (unfortunately, Encana illegally frac’ing the drinking water aquifers that supply my community and water well, forces me to drive for more than I normally would to haul alternate water); live without clothes dryer (I hang my wash out in the sun to dry, summer or winter, I love the fragrance when I bring it in), air dry my dishes (and hair), etc. I unplug everything not in use. I quit all fun things that require energy such as down hill skiing (even though I love and miss it); my entertainment is to open my door and go walking or sit by an open window and listen to the fast vanishing birdsong; worked like a fiend to restore the native grasses on my land (I bought my land not for me, but for native grasses, birds and wildlife), only to watch Encana invade and bring in many miles of roads, endless leases and facilities on fragile prairie lands, masses of weeds; etc.

My biggest pollution reduction remains the choice to have no kids. It’s the only thing I did right in my life.