Excessive and growing human numbers are a leading cause of decreasing biodiversity in many parts of the world. In researching a paper on this topic last year, we became aware of the large amount of good scientific work recently published on it. In an effort to spur more such work, we are publishing an annotated bibliography describing this new literature and helping readers access it more easily.
by The Overpopulation Project
Our new bibliography of recent scientific work on population and biodiversity aims for comprehensive coverage of peer-reviewed scientific papers published during the past dozen years that deal substantively with the connection between human numbers and biodiversity loss and preservation. Its 160 entries also include a few books, and select publications from the previous decade which treat this topic. Entries include publication data, a hot link to the source, and a one-sentence description.
There’s a lot of good new work in this area! Compared to 10 or 20 years ago, biologists seem more willing to speak plainly about the roles population growth and population density play in biodiversity loss. Pleas for more work on the fundamental drivers of biodiversity loss by Reed Noss and other conservation biologists appear to have been heeded.
Our entries document work on population and biodiversity in many parts of the world, from China:
to India:
- Krishnadas et al., Parks protect forest cover in a tropical biodiversity hotspot, but high human population densities can limit success,
from Europe:
to Africa:
- Mengistu and Ayano, The Impact of Population Growth on Natural Resources and Farmers’ Capacity to Adapt to Climate Change in Low-Income Countries,
from North America:
- Radeloff et al., Housing growth in and near United States protected areas limits their conservation value
to South America:
- López-Carr and Burgdorfer, Deforestation drivers: population, migration, and tropical land use.
These articles cover various taxa and groups, from herbivores:
- Berger et al., Disassembled food webs and messy projections: modern ungulate communities in the face of unabating human population growth
to carnivores:
- Boitani and Linnell, Bringing large mammals back: large carnivores in Europe,
and from fish:
to insects:
- Sánchez-Bayoa and Wyckhuys, Worldwide decline of the entomofauna: A review of its drivers.
There are also many valuable global overviews, such as:
- Seto, A meta-analysis of global urban land expansion,
- D’Odorico et al., The global food-energy-water nexus, and
- Crist et al., The interaction of human population, food production, and biodiversity protection.
The Intergovernmental Panel on Biodiversity and Ecosystem Services’ Global Assessment (2019) identified increasing agricultural demands as a leading cause of terrestrial habitat loss and degradation. We found numerous recent publications affirming the key role population growth plays in driving the agricultural conversion of natural habitats, including:
- Laurance et al., Agricultural expansion and its impacts on tropical nature,
- Ngwira and Watanabe, An analysis of the causes of deforestation in Malawi: a case of Mwazisi, and
- Raven and Wagner, Agricultural intensification and climate change are rapidly decreasing insect biodiversity.
This scientific consensus is important to remember in the face of ideologically motivated claims that agricultural demands can be decreased regardless of the number of people we are trying to feed.
In addition to the main listings, our new bibliography includes two addenda: a list of select publications on the connection between population and climate change, and a select list of work on the ethics of biodiversity loss. The recent literature on both topics is large and these addenda only provide an introduction. Nevertheless, we included them as dealing with important adjacent topics that we believe will be of interest.
We are glad to see this resurgence of interest in population among conservation biologists and conservationists more generally. As Crist, Ripple, Ehrlich, Rees and Wolf wrote in last year’s Scientists’ warning on population, “humanity must commit to transformative change on all levels in order to address the climate emergency and biodiversity collapse. In particular, stabilizing and ultimately reducing the human population size is necessary to ensure the long-term wellbeing of our species and other life on Earth.”
Readers curious about the main lessons we take from this literature are referred to our publication in Biological Conservation, “Overpopulation is a major cause of biodiversity loss and smaller human populations are necessary to preserve what is left.” We appreciate corrections of existing entries and suggestions for additional ones to this new bibliography. We also welcome any information about ongoing work in this area, which we are happy to share with our readers!
Read the full bibliography here.
The name of the project implies that the problems of ecological degradation are endemic to the TooManyPeople in that area.
Isn’t there an implicit gap between the numbers and the effects on the ecosystem based on the rates of resource consumption relative to the resource availability ?
I encourage your analyses to go beyond the “TooManyPeople” narrative – which does carry an essential truth – to include the effects of ecological and social and economic degradation by centuries of Imperialist Colonialist extraction, and exploitation – which typically carries on in the form of cronyCorpiratism and discriminatory economic policy and geopolitics by hyper-consumptive hyper-emissive dominator cult-ures.
I am curious how much the research work itself engages these meta-issues – which might carry their own collateral effects on the research…
Certainly these meta issues are important to be incorporated into your work as neta-reviewers and analysts.
One topic caught my eye…
The matter of greedy land speculators and real estate developers in overriding common sense and ecological evidence and regulatory protection to assault threatened areas by building their poorly engineered shitboxes right next to them or in flood zones … Sure, one can analyze the detrimental effects as they occur – it is important to show how those harmful effects were predicted, anticipated, fought against, and yet allowed to proceed through sheer corruption and collusion and dereliction of duty-of-care obligations by Apparatchiks in public office.
I invite you to check out this truth BOMB for an incisive look at the degradation which is endemic to most of the dominator cult-ures but is particularly acute and toxic in Amerikkka
Kurt,
Domination, exploitation, discrimination and greed … it would be nice if these problems were only found in “western” nations. Unfortunately, people everywhere seem capable of treating one another unjustly. Africans didn’t need training from Europeans in enslaving their fellow human beings. Mayans and Aztecs didn’t need training in slaughtering their captives en masse.
As for “greedy land speculators and real estate developers,” sure, it’s great to rein them in with the right policies. But as long as there are more people, they will need houses etc. and that will have to be provided somehow, with other species taking the hit.
If my town adds a hundred thousand residents in the next few decades, as we are on track to do, the relative greed of the real estate agents won’t have much to do with the environmental impact. Nor will the race or ethnicity of the new residents.
All those greedy corporations are selling stuff to somebody and employing people en masse, aren’t they? They don’t exist in a vacuum. We make sure they exist and keep being greedy because we buy their stuff, invest in their shares (e.g. pension funds), work for them, vote for politicians who give them money.
Also, what’s with the triple K trend lately? So gross.
There is a paradox here, however. The people living in low human density areas and in the most wild environments find themselves most at conflict with wildlife. This is true in Europe, Africa, Asia, everywhere.
I think the refusal by conservationists to address this paradox and the exclusive focus on “wilderness” are undermining public goodwill towards conservation efforts. People who live in cities and whose votes and opinions weigh more are dismissive of the real problems caused to lower-income, less visible, lower densities communities by coexistence with certain species or ecosystems – while they themselves never have to give up anything in favour of wildlife, since they live in cities and buy all the things they need, as opposed to having to grow them, produce them, or hunt and forage for them.
Bears and wolves, and now boars, are a perfect example of this, but there’s many more.
I don’t know if it’s a paradox that people living closer to nature are more likely to have conflicts with wildlife, more like a reality. And it’s also unsurprising that city-dwellers might be less knowledgeable and less willing to accept compromises (such as killing “problem” animals) than rural people who are dealing with these problems more directly.
Such problems demand compromise from both groups. Hopefully these compromises still leave room for flourishing populations of native species, including the ones we find problematic. Hopefully too, they leave room for leaving some places wild: unmanaged by people, or relatively unmanaged; places where the landscape is primarily a function of natural processes rather than human actions.
Not all places can be wild, and even in designated wild lands compromises must often be made. But that goal — some areas left natural, not human-dominated — is a worthy one. And if some countries are so long-settled or densely populated that they don’t have room for wilderness, then I would say they need to make room — in part by decreasing their populations.
But I don’t know: perhaps that’s just my American experience talking (America with a “c”, not three “ks”); a tradition with deep roots (Thoreau, Muir, Leopold, Carson). I’m interested what people in other parts of the world think about wilderness as a necessary or unnecessary component of biodiversity conservation.
I agree with all you say, including that the American perspective is a bit different (though I’d recommend this: https://faculty.washington.edu/timbillo/Readings%20and%20documents/Wilderness/Cronon%20The%20trouble%20with%20Wilderness.pdf)
Although it needs to be said that in the Americas (all of them) the arrival of the Europeans caused such a rapid and dramatic decline in the indigenous human populations, sometimes even before actual contact, that we still don’t realise how places we now consider the ultimate wildernesses, such as the Amazon, were actually quite inhabited.
There is too much to be said about this to summarize it in a comment. The only thing I’d add is that we need to learn to think about wildlife in its more “humble”, closer-to-us form, as well, not just the so-called charismatic animals, and that wildlife corridors are a good compromise because they could cross more densely populated areas too, and share not just the joy but also the “burden” of conservation more equitably.
An excellent resource, thank you. To pick up on your query re wilderness. In South Africa we have vast, fenced off wilderness areas, the most famous being the Kruger National Park. They are fenced to protect wildlife as well as people. Lions, elephants, rhinos, hyenas etc don’t mix well with modern urban or farming areas! You have to stay in your car inside the Kruger except for specified fenced ‘rest camps’. These areas provide economic benefit through tourism, including by locals. Visiting national parks is part of the South African way of life and keeps us connected to our natural heritage.
“Biologists seem more willing to speak about the roles population growth and population density play in biodiversity loss.”
I think that’s true, and it’s a good thing. But, at the macro level, world science seems very much on message with the UN and the politicians – Climate Emergency, Climate Change, Net Zero.
And that’s not such a good thing. Because it tends to support the fantasy that “saving the environment” can be decoupled from the eight billion.
Even in the realm of climate change, more and more scientists are weighing in on the need to address population, even if the politicians haven’t yet followed. See one of our entries:
Ripple, William et al., 2021. World scientists’ warning of a climate emergency 2021. Bioscience 71: 894-898. https://academic.oup.com/bioscience/article/71/9/894/6325731
A very handy bibliography, great work!
Thanks Kelvin!
Totally unrelated, but I didn’t know where to put it and I think it’d be an interesting topic for this blog:
https://www.instyle.com/esgar-guarin-vasectomy-revolution-7095975
I know it’s a fashion/celebrity magazine, but even better as it shows this subject is going mainstream. Although I really wish people would still say the word “women” instead of those ridiculous paraphrases that are fashionable now…
David, Africa is a different story. From what I know, even though there’s been issues even there with indigenous people being evicted from their lands to make room for “conservation” and parks, the biggest source of conflict is demographic and economic growth. Africa has most of the last megafauna left in the world, the rest having been hunted to extinction by humans everywhere from North America to Australia.
I totally support protecting Africa’s amazing fauna and the huge habitats it needs to survive, although I believe that tourism is a tricky way of doing it, since as Covid has shown tourism can collapse very fast and then what are people going to eat? I prefer a combination of tourism, if there must be, combined with other activities (such as hunting, foraging, handicrafts…) that you can still rely on should tourism stop.
Europe is the opposite. The areas that are rewilding are those humans are leaving; unlike Africans, we are mostly not expanding into rural or wild places, with a few exceptions, because we had already done that in the last millennia. We are now retreating, which is good. However, the people who are left in these wilder places are being forced to accept *all* rewilding, and give up their traditions, lifestyles and economic activities whenever there’s a conflict. This sometimes opens the door to more, not less, environmental exploitation, for example with hydropower in the Alps, or tourism.
At the same time, subsidies are being given to people who do choose to stay in remote areas or move there – this is totally contradictory with the other pressure I just mentioned and shows that we as a society don’t really know what we want.
So what do we do? I have my own ideas about possible solutions, but they should start with shrinking our footprints, beginning with land use, homes and infrastructure, and this is really hard to convince people to do, though we must.
Gaia (and David),
biological conservation is highly complex, and what we see preserved are often historical products (e.g. some Swedish national parks with species-rich meadows assumed to be “climax”, the biologists didn’t realize they were products of peasants, mowing for hay, etc). Currently, we have a trend in the literature showing that also small protected areas are valuable (part of a debate, SLOSS, “Single Large Or Several Small). Conservation work and success is to a large extent determined by properties, property size, and owner (state, private, etc). In Europe, the highest proportions of private land are in France and Norway (!), thus with strong private interests, and expensive land to buy, for the state. Southern Sweden is the same, but there is a gradient of more company/state land northwards. However, the presence of the Sami people and domesticated reindeers (and some companies) exclude the possibility of large rewilding there. Every European country (and other countries) has its own conservation history and problems. By the way, the most wonderful pictures of large wild natural areas I have seen in the northern hemisphere comes from Russia, take a look at photots from the Zapovedniks here: https://en.wikipedia.org/wiki/Zapovednik
PS. David, probably my best memories of nature and wildlife comes from Kruger, in 1998. I sometimes argue for “large” fenced areas in Sweden
/Frank
Note: just because a group doesn’t have a history of recognizing wild nature, or a country doesn’t have a history of setting up wild parks or wilderness areas, does not, in itself, mean they should not do so going forward.
Afghanistan doesn’t have much of a history of women’s rights, at least not recently. But that doesn’t mean women there shouldn’t have rights.
Similarly, people in one place or another may not have ever thought of leaving wildlife or wild places wild. But they should, particularly now that people are overrunning the world.
Thanks Frank and Gaia for your comments. Glad you enjoyed the Kruger, Frank! Yes, I agree Gaia, the situation in Europe and Africa are polar opposites. In Africa we still have a chance to save large areas for wildlife. But without clear government protection, those areas will come under increasing pressure from a rapidly growing human population and expanding impact.
Land ownership: I believe that many systems actually reward large private land ownership through tax breaks, low inheritance taxes, agricultural or other subsidies, and tolerance for high inequality. I’m looking into Georgism (the economic theory) for analysis and possible solutions. There’s also a lot of internal colonialism in Europe whereby rich people buy a lot of land where it’s cheap (e.g. Romania, many parts of Italy), thus raising prices and taking it away from both local people and wilderness. No one speaks about that.
I personally believe that parks and wild spaces should be government- or community-owned, and bought back from people where possible. Paying farmers and other private landowners to “rewild” is risky and ends up rewarding inequality further (these people will basically be rich people paid to do nothing and still enjoying their own land as private). Mixed and traditional uses are different.
P.S. A very interesting “rewilding” story from Italy: https://it.wikipedia.org/wiki/Lago_ex_SNIA_-_Viscosa
In a nutshell, it was a former viscose factory, the ground was drilled for construction, they broke through to the water table and had to give up, the water welled up and formed a pond, it spontaneously filled with wildlife in a not very green area of Rome, people are clamouring for it to be protected but the owners want to build a warehouse and politicians (very corrupt in Rome, of course) are dragging their feet.
Shows how strong economic interests are, even when faced with a pro-wildlife urban public opinion.