That’s the title of a paper just published in Biological Conservation in response to TOP’s recent paper on population and biodiversity loss in that journal. Are its authors right?
by The Overpopulation Project
In one sense, Alice Hughes and company clearly are correct. Efforts to protect wild nature are ongoing throughout the world, and for the most part they take place with no attempt to link them to human numbers, either by biodiversity conservation practitioners or the wider environmental movement. Like efforts to mitigate climate change, or curb air or water pollution, efforts to protect other species do not typically address human numbers, even where those numbers are immense. So clearly, people can work for biodiversity conservation without addressing overpopulation.
The real question, though, is whether we can achieve biodiversity conservation at current or higher human numbers. By all accounts, global biodiversity is rapidly decreasing. There is overwhelming evidence that higher population densities increase pollution, habitat loss, overharvesting, and the other direct drivers of biodiversity loss. So it is hypothetical at best to claim that we can reverse biodiversity loss without addressing our growing numbers. To us, this hypothesis seems quite unlikely. But in our paper, we ask conservation biologists to explore it.
What we call success in biodiversity conservation depends on how high we set the bar. If the goal is to preserve robust populations of all their native species, then probably few countries around the world can achieve it at their current population levels. If the goal is merely to slow current rates of habitat and species loss — to lose global biodiversity a little slower than we otherwise would — we can probably do that without addressing our own numbers. Hughes et al. are careful not to specify concrete goals for biodiversity conservation, the better to argue that addressing population isn’t necessary to achieve them. But those committed to getting at the truth of these matters and conserving biodiversity permanently need a more rigorous approach.
In our paper, we stipulate that overpopulation exists where people are displacing wild nature so thoroughly that they are extinguishing numerous other species, and this cannot be avoided without significantly decreasing the size of the human population. This definition has both empirical and ethical aspects. Empirically, it implies that human numbers are an important determinant of human impacts on biodiversity. The evidence for this is overwhelming, as we show in our paper and document in a recent bibliography of research on population and biodiversity conservation containing over 160 citations. Hughes et al. resolutely refuse to engage with the conservation science literature (in a rare case where they do, they cite an article from Camilo Mora to support their contention that high population levels do not lead to biodiversity loss, when his article claims the opposite and laments that population is “a fundamental but fading issue”).
Ethically, our definition of overpopulation implies that human beings have a moral responsibility to limit our environmental impacts to levels that do not extinguish other species. That commits us to speaking clearly about difficult ethical and economic issues, and the trade-offs necessary to create societies that don’t displace other species. Hughes et al. are free of this commitment, since they set no explicit moral limits to human expropriation of the resources and habitats other species need to survive. Thus they are free to criticize the creation of protected natural areas, for example, because such areas limit human economic activities. Hughes et al. neither acknowledge the rights other species may have to the resources in such areas, nor the fact that protected areas are essential to preserving Earth’s remaining biodiversity going forward, nor the practical difficulties this raises in a crowded world with many competing needs and demands.
Instead, from an imagined position of moral superiority, they charge those who raise population issues with an open-ended list of ethical transgressions. We are “neo-Malthusians” unconcerned about human rights abuses, “neo-colonialists” dictating how brown-skinned people in the developing world should live their lives: all in all, pretty rotten people. In wielding these accusations, they claim that the only means to intervene to lessen population growth are coercive measures that violate human rights, such as occurred under China’s one-child policy. This claim follows a long tradition of rewriting history in order to silence population concerns. The existence and success of many voluntary family planning programs around the world over the past sixty years – are they even interested in this? Women’s right to choose how many children to have does not appear to be on their radar. We advocate for rights-based, voluntary family planning programs, for which the need is huge.
Hughes et al. say, “whilst declines in fertility and birthrates are generally the bi-product of holistic conservation and development programs, there is no need for population reduction to be the main goal.” They offer no evidence for this conclusion. Yet robust analyses show that the greatest determinant of fertility decline has been the strength of voluntary family planning programs, while general “development” has played little role. Where conservation programs have been sufficiently “holistic” to include family planning and reproductive health components, such as under the Population, Health and Environment (PHE) model, then the synergies between natural resource protection, fertility reduction and livelihood improvement have achieved strong results across all three goals. But where the population issue has been ignored, conservation efforts have not reduced fertility. Overall, their central conclusion, that “not only is there little evidence for ethical ways of imposing control on human population, but there is no scientific evidence that overpopulation, or more accurately, high population, is a direct driver of biodiversity loss,” flies in the face of overwhelming evidence gathered in the demographic and conservation biology literatures, respectively.
Hughes and company mischaracterize our paper in many ways, most of which are unlikely to interest anyone besides the authors. But one is too important to overlook: they say “Cafaro et al. (2022) argue that overpopulation is the major cause of various environmental issues such as biodiversity loss and climate change.” In fact, the paper’s very title asserts “Overpopulation is a major cause of biodiversity loss” and we are careful to reiterate that point several times in the text. A whole section of our paper is devoted to entreating conservation scientists to explore the relative impacts of population and other fundamental drivers of biodiversity loss. We fully agree with Hughes et al. that smaller human populations are not a sufficient condition for biodiversity conservation. They must be combined with efforts to rein in per capita economic demands, so that total human impacts on the biosphere decrease. When decreased economic demands are combined with more efficient and less polluting means of satisfying those demands, human societies will be on the way toward fairly sharing Earth with the rest of life.
Excessive overall economic activity and an unfair hogging by people of Earth’s limited resources are the fundamental causes of rapid biodiversity loss. Too much total consumption and production are the problems, and total consumption and production are a function of per capita consumption times the number of people. To think we can address excessive consumption while ignoring the number of consumers is delusional. It assumes an infinite ability to decrease per capita consumption which simply does not exist.
Hughes et al. embrace this delusion throughout their paper, particularly in their treatment of agriculture. They write, “reducing meat consumption is an essential component of addressing habitat loss and degradation” — but not reducing the number of potential meat eaters. “Expansion of fishing pressure is largely from large companies registered in developed countries” — but this fishing pressure apparently is unrelated to the number of potential seafood consumers. Increasing consumption of biofuels leads to tropical deforestation — but this increased consumption has nothing to do with the number of people that use the biofuels. In the end, Hughes et al. place their hopes in a technological miracle, calling for “an agroecological transition in both high and low-income countries to minimize the impacts of agriculture on local biodiversity whilst maintaining food security, which is sustainable regardless of population size.” It is hard to believe such a statement made it through peer review in a reputable scientific journal.
No agricultural system is sustainable “regardless of population size.” Recent studies asking whether humanity will be able to feed itself in 2100 without seriously damaging the biosphere are more or less optimistic. But they all find the challenge very difficult and recognize that higher human populations make it even harder. The complexity of feeding 9 or 10 billion people without degrading the ecosystem services we depend on, the massive changes that will be necessary in order to do so, the uncertainty about whether humanity is up to the challenge—all these make a mockery of the idea of “maintaining food security … regardless of population size.” According to the 2019 IPBES Assessment Report, agricultural expansion is a leading cause of terrestrial biodiversity loss and is set to remain so in coming decades. This demand is obviously tied tightly to the number of consumers for agricultural products. Just as obviously, the human demand for food will trump other species’ needs for habitat and essential resources when they conflict.
Hughes et al. emphasize the outsized role developed-world consumers play in driving biodiversity loss in the developing world. It’s a valid point, yet hardly a convincing reason to ignore population matters. Decreasing bloated populations in developed countries is necessary to preserve global biodiversity, as our paper explicitly states. Doing so both opens up opportunities for rewilding within their own borders and decreases their economic demands on wild lands elsewhere. Just because a population isn’t growing does not mean it represents a fair distribution of habitat and resources between people and other species. In most cases in the developed world, the reverse is true. For us, that means that most developed nations should set achieving smaller populations as a key environmental policy goal.
It seems to us that those with a serious commitment to preserving biodiversity should advocate for smaller families, universal availability of modern contraception, and smaller populations in both developed and developing nations. But perhaps we are missing something. We invite the authors of “Smaller human populations are neither necessary nor sufficient” to respond to this critique, in a future blog here at The Overpopulation Project or in the comments section below.
30 thoughts on “Smaller human populations are neither a necessary nor sufficient condition for biodiversity conservation”
Yes, there is too much focus on ‘slowing population growth’, rather than the ubiquitous benefit of smaller families irrespective of whether the human population is growing, stagnating or even shrinking. If we focus on population Growth, we will be confronted with the (partly valid) argument that this growth occurs in ‘small footprint’ countries, and that slowing it will do little in the short-term. Whereas looking at benefits of family size widens the responsibility to socalled developed countries who are to blame for all this mess. Creating Zero Footprints (one fewer child) in these countries has a massive beneficial effect.
Well, you are just WRONG!!!
Most population growth–due to exponential growth and high immigration–is happening (both in net increase and IMPACTS) in the 3 most populated nations on Earth: China, the U.S. and India, in that order! IT IS NOT THE POPULATION GROWTH IN DEVELOPING NATIONS, Ivan, that is our problem! (Consider, the sub-Sahal nations with a 3 percent growth rate but carbon emissions of .03 cubic tons of carbon per year, in contrast to our 18 cubic tons per-capita!)
A child born in sub-Sahal Africa will NOT own a variety of cars, will not globetrot in jet planes, or live in a house with central air and every other “indulgence,” part of why, at one point, Britain’s ROYAL ACADEMY OF SCIENCE said that one child in a First World country was often equal to up to 60 IN A DEVELOPING NATION! Consider, just one child in the U.S. will have an annual CARBON EQUIVALENT of 3 in China, in effect, meaning that the U.S. is a carbon-equivalent nation to the 1.3 BILLION living in China, while we are the carbon-equivalent of most developing nations many times over!
And, strange, 54 NATIONAL ACADEMIES OF SCIENCE, as far back as the 1990s, disagreed with you, saying NO environmental problems can be remedied without addressing population, though if you need some more current, roughly 19,000 CLIMATE SCIENTISTS said it in November of 2020, though Big 6 Media made darned sure NOT TO REPORT IT.. They said that to solve climate change, we MUST address population, especially in, duh, the HIGH-CARBON NATIONS, CHINA (which is losing population, fortunately), the U.S. (now one of the fastest growing nations ON EARTH) and INDIA also with a stable-to-decreasing population!
So, Ivan, if you want to look at OVERPOPULATION, look in the mirror and stop believing Big 6 Media’s version of population! They lie!
Kathleen, I thought I recognized your name. You wrote the piece in the latest NPG letter I received (Modern Megadrought). I was on the Seattle Chapters board of ZPG for 8 years and we did have some interactions with both NPG and The Sierra Club (this was back in the late 90’s and early 20000′). One comment I have made to NPG involves wording about immigrants (the issue should be about a system and not people). Continuing to refer to immigrants as illegal aliens is a conservative tactic and is unbecoming for an organization based on science. I also dislike the liberal reference of undocumented immigrants (it trivializes the issue). We have laws and people (immigrants) who break those laws should be deemed illegal immigrants. I have mentioned here and will mention again my late partner, an immigrant from Iran) once asked her 2nd graders which is more important, people or dirt? She fully understood the problems with excessive immigration. It’ not that hard. To her the systems (political and natural) should be paramount. Your article in NPG only highlighted that fact. Thank You.
it seems to me you are focusing on climate change in your reply, use of fossil fuels, but not loss of biodiversity which is related but different. England, China, India as well as Kenya and Brazil are all destroying other species to satisfy human wants. Of course fewer humans would lessen this crisis. Lifestyles can vary on carbon footprint but every human needs similar amounts of air, water, food and space to occupy.
All countries are responsible for this mess, not just the “developed” ones. Should be obvious by now!
Also, the population growth occurring in “small footprint” countries (that aren’t really small footprint a lot of the time) translates into migration and population growth in “big footprint” countries, so the two phenomena are related.
P.S. A reminder of a Sierra Club bumper sticker–before they backed off the topic of population as the terms to keep a multi-million-dollar contributor happy!–that Sierra Club executive director Carl Pope, himself (before he started character assassinations of those who disagree with him on immigration, ordered the Club to print and circulate: The U.S.: THE WORLD’S MOST OVERPOPULATED NATION!
At one time ZPG and the Sierra Club coordinated in putting out a mini-convention on overpopulation in the Seattle Center. We worked together for two years and brought in people who were prominent in the 1994 UN Convention on overpopulation in Cairo Egypt. It seems they both backed down on the influence of immigration around 2000. The problem was, as you noted, one of money. A new director for ZPG started to court moneyed people (Ted Turnier was one). In return we had to do something for the donators (Ted Turner was married to Jane Fonda at that time). A PBS production, ‘To the Contrary’ with Bonnie Erbe put out a video (which I still have) talking about the money and overpopulation connection. Supposedly $100 million was donated to both organizations by an anonymous donor in return for lessening the comments on immigration.
After reading your report in the NPG newsletter this link showed up. https://www.yahoo.com/news/water-crisis-west-massive-reservoir-100009040.html In the county, where I live more and more people are getting salt water intrusion in their wells (especially those living along the coast). Of course some are saying we need more de-sal units but, some of us, as I, are installing rainwater harvesting systems. This not only gives us a source of pure water it also helps the aquifers recharge. Here, on Lopez, we have the highest recharge rate in the county a whopping 9.8 %.
It’s kind of a moot point now anyway. The low lying areas where most people are concentrated, and the best land for growing is, are going to be under water soon, whatever they do now.
I was amazed, recently, when a seemingly educated carer of mine was grieving over the lives lost to the Turkey earthquakes, but when I tried to explain about their cause, and why so many people were living in dangerous places, I found that he had never heard of continental drift and never thought about how mountains are made. He had never heard of massed extinction events, or even of geological periods of millions of years, let alone billions! He did not know that world population had nearly quadrupled in one lifetime or that there were eight billion competing for vanishing land and resources now. He did not know that sea level was rising, and was visibly shocked when I showed him this video! He showed me his own video of his baby daughter enjoying her first afternoon sat out in the sunshine.
This is a young man who has travelled the world much more than I have, and has worked in high tech environments in ultra modern cities, but he really didn’t have a clue about how the world works, or of any of the dangers it is in.
So: what chance of explaining this to the uneducated masses, who want nothing more than to have their own happy children enjoying their first day in the sunshine?
I don’t think that in the specific case of the earthquake the problem is that people are living there at all. A great number of countries are at high risk of earthquakes and you can’t evacuate all of them permanently to protect people from a once-a-century kind of event.
The problem rather is that building properly and having an efficient response both cost a lot of resources, and if you’re already stretched to the limits or beyond, you won’t be able to invest in prevention and rescue.
Thanks for the video – and the honesty. Even without rising sea levels, population explosions in the Developing World are not biologically sustainable. It is hard to understand how any biologist or naturalist could fail to know the inevitable result of population explosion in any species – namely, population crash. But there is something about modern “education” which – as you point out – leads to masses of letters after your name and yet no realistic overview of how things fit together. Things have drifted into being arranged in unconnected “silos” in all subjects. Also, if you want a “career” (horrible word), there is no way you can mentiion human overpopulation – even in your sleep.
It must be really frustrating for you to be repeating the same reasonable and documented things over and over to people who aren’t listening anyway.
The website of British charity Population Matters regularly features articles by African (or Asian, or Latin American) men and women who are talking about why family planning is needed and wanted in their countries and important to them. Maybe after a gazillion articles of this kind appear in the media, stupid comments like “who are you to tell brown people not to have children” will disappear.
Well Gaia, life is full of frustrations! But we do what we can. I wouldn’t bet that the authors of Hughes et al. will listen to reason on population matters, but I’m more hopeful of the readership of Biological Conservation, and the community of conservation biologists. They are groping their way toward seriously engaging with the fundamental drivers of biodiversity loss, including overpopulation, and I think our continued failure to protect what they care about is a powerful incentive to think more realistically about these matters. We will see.
Events will force them to admit the painful truth – and in a way, this tiny minority of humans is irrelevant. The millions on the front line of Overshoot know what happens when humans become too numerous for their available resources. Even if they can’t read and write – these are not prerequisites for an awareness of reality, in fact they seem to block out such awareness a lot of the time.
“None do blind as those who will not see”
Simply watching, for 8 decades, the expansion of dwellings into pristine land, of animal farming into virgin rainforest, of crop growing in virgin rainforest, of open cut mines into rural land, of solar farms across valuable agricultural land, of wind farms across waterways, of rubbish dumps across natural landscapes, tells us that WE humans are gobbling up the surface of the earth, and its capacity to feed us, at a rate that will ultimately exterminate most life.
And WE, all 8 billion of us, are contributing both wittingly and unwittingly. Developing world people justifiably want to and should achieve the level of food, housing and wealth security that the developed world has, and that adds to the problem.
Population control, as onerous as it sounds is the key to saving our one planet.
I particularly liked your point that the “population can grow forever” position is based on false assertions while the “ending population growth is essential” position is backed by data. The false assertions may come from a pro-growth agenda “sold” by those who think they profit from growth. But, like the “zombie economics” ideas that Paul Krugman debunks, these false narratives reappear endlessly, still without evidence to support them, and even while evidence that growth is killing the planet accumulates and becomes irrefutable.
Yes. And it’s particularly worrisome when environmentalists and others with a generally left-leaning politics start parroting the pro-growth agenda, because they think their humanitarian commitments demand it. Left or right, it’s never a good thing when your ideology leads you to deny obvious facts — like the notion that more people tends to lead to more consumption.
How can anyone seriously think population can grow *forever*?
Maybe we should use math and logic and the reduction ad absurdum line of argument. At least we should be able to agree that at some point the population will HAVE TO end, so why not now? That’s not even an argument, it’s a fact.
These prestigious articles and publications have become superfluous in recent years – because events have overtaken them. Also, it has become obvious in many cases (e.g. medical journals), that much of the research is undertaken in order to obtain funding, which knocks out any non-profitable topics even before their inception. Profit lies in prolonging human life, not curtailing it, so long as welfare dependency does not eat into government revenues and make governments reluctant to endorse privately-funded science.
These journals and their contributors are still locked in the post-Enlightenment liberal worldview, where Progress is linear and the only way is up and Growth is limitless and Motion is perpetual. Meantime millions of illiterate people know what happens when your population goes from 21.5 million in 1950 to 84.5 million in 2020 (Turkey, not counting huge Diaspora), or 3.5 million in 1950 to 17.5 million in 2020 (Syria, not counting huge Diaspora). Everything non-artificial starts to run out – including Water. Then ethnic hatred, civil war, and even war, arrive. But even so, human numbers do not shrink much.
Ask the millions pouring across the border between North and South America, or between Africa and Europe, or between Asia and anywhere, to say truthfully why they are forced to flee. They know why, in their heart of hearts. They blame civil war, or gang warfare, or lack of jobs, or drought, but they know perfectly well what the ultimate cause of all these things is. They can’t say so, but at least they know. It strikes me that many academics not only can’t say it, they don’t even know it – they operate in a cocoon, even though they travel the world constantly in pursuit of Knowledge at considerable cost to governments and funding corporations. Eventually, the physical realities of Overshoot will overtake these happy academics and they will change their tune. Until then, there is little point in contradicting them.
One day too, Overpopulation realists will lose the spar they cling to – contraception and the liberation of women – which they imagine will bring about the necessary reduction in human population, in a controlled and civilized manner which will enable Progress to continue (though at a slower rate), or at least stay steady and not decline. But here again, it makes little difference when or if those claiming that plummeting Total Fertility Rates BY CHOICE are the answer. Because soon the fact that they are not the answer will become all too apparent. Not unless they are caused by uncontrolled and unchosen near-total sterility of humans (including men) caused by pollution. We know that DBCP has caused sterility in male banana growers in Latin America, the Caribbean and Africa (and in men at plants manufacturing it) – but other chemicals causing male sterility are not so dramatically effective, though they do have an effect.
It is useless trying to convince activist groups trying to reduce human numbers in a nice kind way that something rather nasty and uncivilized is going to have to do this, in the end. And it is equally useless trying to convince those who are convinced that Malthus was wrong that Malthus was right.
One would have to be like King Canute who was obliged to show his courtiers that he was not all-powerful by actually sitting amidst the incoming tide. Even then, I bet quite a few were not convinced.
Well, contraception and the liberation of women are big steps in the right direction. The evidence shows that they almost always bring fertility rates below replacement rate, and sometimes way below it.
I wouldn’t pretend to know a likely path back from current, massive global ecological overshoot that is painless and certain and preserves genuine progress (as opposed to greater material wealth). It does seem like a challenge likely to overwhelm us — even assuming that we took it up, rather than charging even faster into overshoot.
Still, it is good to see more and more nations with below-replacement fertility. That’s an important part of what needs to happen. Whether its through good family planning programs or low sperm counts!
Extremely well expressed. It bridges the two extremes – me and others on the “It is all FUBAR” side and the “Yes We Can”, “Wir schaffen das” dreamers on the other side. It is with reluctance that I have crossed over to the FUBAR side, of late. Michael Dowd and his Post-Doom videos on youtube have helped me across and I am now happy as a pig in clover, having found an honest milieu, at last. There is something about moving to Acceptance, after years of Denial, then Anger, then Bargaining, then Depression, that is completely exhilarating.
I read the Hughes et al paper with ever increasing astonishment! How can biologists claim that populations can grow for ever without limit? There are so many examples from the natural world – in some areas of southern Africa, elephants have become too numerous and are causing massive degradation. There has to be a limit on human population, the only question is what that limit should be? Would Hughes et al be happy with a world of 20, 30 or 40 billion people? I admire your patience, Phillip C and colleagues. Please keep on beating the drum.
Thanks David. One paragraph in our reply, which got excised due to length, leaned into your elephant point. It asked what biology would look like if we tried to explain biological phenomena without reference to the size of populations, or changes in their size.
I mean, its such a commonplace of biological and ecological research that you don’t even think to mention it, but its often about whether this kind of organism is increasing in numbers and how that impacts this other kind of organism. If this change occurs in the environment, how does that affect numbers of X or Y, and how do those changed numbers affect W and Z in turn.
But then, we have one kind of organism — humans — that is unique in the ubiquity and severity of its impacts on the biosphere — and we’re going to try to understand and limit those impacts without addressing our numbers. It’s truly senseless
Again, unrelated, but very interesting: https://www.irrawaddy.com/opinion/guest-column/the-quiet-rohingya-population-explosion-in-coxs-bazaar.html
I wonder why the author says that “aggressive” birth control in refugee camps doesn’t work.
One fascinating thing about humans, and possibly other creatures, is that often the most dire the situation, the greater the desire to live and breed. Suicide rates in Nazi concentration camps were very low. High suicide rates and low fertility are commonly associated with wealthy and safe countries such as the ones in Northern Europe or East Asia.
Refugees, possibly the unluckiest people in the world, have a lot of children. This personally makes me really angry for a few obvious reasons, but it needs to be looked into dispassionately. A suggestion for a new post 🙂
Thank you for the link. I remember an item in ‘The National Geographic’ about this issue. Of course some of the details were missing. Things like explain why the political system, then, was overturned and the military took over. The same thing is happening in this country and, I suspect, other countries as well. An early Stanford project (starting in the 70’s) on Existential Risk mentioned in impact of overpopulation on politics. The prognosis was that things would take an ugly turn at this time.
In the case of Myanmar, no, it wasn’t overpopulation why the military took over. It’s actually a relatively sparsely populated country, for Asia especially, rich in natural resources that all its neighbours are plundering, and THAT’s why the military is in power (although there’s very fierce resistance right now).
Biodiversity has both quality and quantity components.
Natural enemies provide quality and quantity control.
We humans have disrupted the process by suppressing our natural
enemies to extend lifespans artificially, at the expense of other
species, future generations, the environment and average quality
of our members. It isn’t too much to ask the authorities to turn
the clock back on some immunization, in order to achieve population
control or reduction under more controlled conditions than would arise
under the normal political process of endless war punctuated with
I don’t know David. Asking parents not to immunize their kids seems like a less appealing approach than the ones we typically advocate: universal access to contraception, incentives for having smaller families. I’d imagine losing a child is a lot harder than not having one to begin with; and that incentivizing people to choose fewer kids is easier all around than taking steps for parents to lose more of their children.
Well, we could do both; they’re not mutually exclusive.
If you’re queasy about child mortality, then we could just
propose banning Covid and/or flu shots. We always have options.
I can’t tell if you’re serious or trolling, but comments such as yours about letting people die is one of the reasons people are suspicious of overpopulation activists.