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Ecological Collapse is not an Existential Risk
7 min readAug 13
A lot of environmental groups say that we are destroying the earth, and our short-sightedness will bring the world crashing down around us. At EcoResilience Initiative, we've looked into these claims, and while some of them threaten the richness of the Earth's ecosystems, none of them pose a serious risk to the continuation of human civilization.
The three extinction risks from ecological breakdown are: failure of critical life systems, cascading collapse, or depleting a critical resource needed for our survival.[1] While it is technically possible for ecological collapse to cause human extinction, it seems essentially to be a non-issue. Yes, if 100% of life is wiped out, we cannot survive. But, we likely don't need 50% and perhaps as much as 90% of Earth's species to survive. Each of these require beyond-extreme circumstances to cause human extinction. (Relatedly: the survival of human civilization is not at risk from climate change.)
Critical ecological systems require only a handful of species to operate. Around 1-20 species for each of the fundamental ecosystem services. Meaning ~5,000-100,000 (0.01%-1% of total extant species)[2] should be more than enough for bare human survival.
To get a rough global estimate of required biodiversity for ecosystem services, I multiply each species required count from this table by the number of global biomes (85-500) and get ~5,000-100,000 (0.01%-1% of total extant species). Total biomes are somewhere between 85 (at the Formation level, which would be minimizing global species) and like 500 (at the Division level which would be using locally thriving species). Totaling that up comes out to somewhere around 7,480 (0.086% out of all extant species) and 81,500 species (0.94%) to support global ecosystem services.
Flaws with this estimate: There are unlisted ecosystem services. I’m overcounting since biomes like “ephemeral salt lakes,” “ground water” and “mud plains” would never provide all ecosystem services. Some species could fulfill multiple ecosystem services. Some species could fulfill multiple biomes. I’m undercounting because supporting ecosystem services would be needed.
I think this estimate is really low for global ecosystem service production, but more than required for a handful of humans to survive.
The other 99% of species could go extinct and critical systems for our survival would still function in places around the globe. That’s thousands of years away at current projected extinction rates.
The real concern would be if some ecosystem services are only supported by a few non-redundant species, and those specific species went extinct. A good example of this is nitrogen production: only ~20,000 plant species produce biologically active nitrogen. But plants are just the hosts for nitrogen-fixing bacteria. Many nitrogen-fixing bacteria are free living and these bacteria are abundant and widespread.[3] Besides, we mechanically produce our nitrogen fertilizer via the Haber–Bosch process anyway.
Resource depletion is similarly thousands of years away and unlikely to cause human extinction.
To examine an oft-raised example: topsoil loss is claimed as declining rapidly and irreplaceable on human timescales. But we don’t need to return to natural levels of soil organic carbon. Topsoil is not necessary for modern agriculture. We can simply use fertilizer, irrigation, and calcium carbonate (to counteract acidity) on depleted soil indefinitely. We also have methods to farm sustainably. Cover crops gradually repair the soil during the off-season and are low cost. No till, manure, biochar are other options. Or we can just leave crop residues in place. As it is, half of earth’s soil has a lifespan of 1,000 years or greater.
Another cited extinction risk is that a single species of marine phytoplankton produces ~50% of oxygen. But the atmospheric oxygen reservoir is so enormous that we would be buffered for hundreds of thousands of years if oxygen production stopped completely.
Environmental activists make it sound like we are running out of freshwater. But only 2% of watersheds use 75% of their freshwater. Data centers are not draining our water supply. To be clear, we are choosing to pump truly preposterous amounts of water out of aquifers for agriculture, and this is unsustainable and bad for the environment. But we could be far less wasteful, recycling and desalinating way more. Surface water is returned annually so we aren’t going to “run out.”
Likewise phosphorus and nitrogen are not likely to run out. Phosphorous has 1,000 years of supply, and current processes lose 30% of the material during processing and extraction. It is not being recycled. Nitrogen is extracted from the air using natural gas, but can also be extracted using solar power with efficiency losses of 1%.
Oil, metals, chromium, and minerals are not ecological resources per se, but they have the same basic format - 1) there are vast deposits, 2) efficiency and alternatives are possible, just currently unnecessary.
In general, we would not hit a wall and face a catastrophe. There are moderately more expensive alternatives and we would switch to those once we started to experience scarcity.
Cascading collapse doesn’t seem to occur in the unpredictable catastrophic ways depicted in the threat profile. This has been tested by multiple events of complete ecological destruction - cataclysmic volcanic eruptions, Agent Orange, mountain top removal, and other real-world instances of total ecological collapse. We didn’t see cascading collapses or unexpected bleed-over. We do see unexpectedly speedy and robust recoveries.
However, as ecosystems weaken, they will probably become more prone to these feared collapses. So the question is: how far can ecosystems collapse before they become unstable? The Netherlands has only 28% Biodiversity Intactness Index or 15% remaining biodiversity according to the Atlas Leefomgeving, yet it seems to not be notably at risk of ecological collapse. In this scenario of simultaneous correlated degradation, cascading collapse would need to cause the unexpected eradication of one of the non-redundant 5,000-100,000[4] species necessary for human survival. But it seems likely that we would be actively tracking and managing the few species keeping us alive at such levels of depleted biodiversity. I think it would be more accurate to imagine this resembling a farming disaster, more than the usual depiction of an unforeseen ecological catastrophe.
More importantly, what would take us to that point of 99% global species extinction? Greed? War? Bioweapon? Climate apocalypse? Basically it would be other problems that would cause us to reach such a far-gone state, and ecological collapse could only really be the straw that broke the camel's back. It does not pose a current threat, nor a plausible future threat without bigger and worse catastrophes.
Ecological collapse won’t lead to human extinction. As an existential risk factor, it is small relative to other extinction risk factors. There are a lot of giant ecological catastrophes, but they are localized and not truly global-scale events. They don’t translate into a threat to civilization much the way earthquakes aren’t a threat to civilization or an existential risk factor. Ecological damage worsens humanity’s situation somewhat, but not so much worse that it demands specific attention as a contributing factor in existential risk. But what about the worst-case scenario for ecological disasters? How bad would it be? What if they all happened simultaneously?
This deserves its own article but I’ll enumerate some potential ecological disasters worth considering:
Landslides, flooding, storm surges worsened by deforestation. Soil degradation, desertification, salt water intrusion, other causes of permanently degraded productivity (including marine!). Herbivore overpopulation, pollinator loss. Invasive species, crop pests, toxic zooplankton, venomous species outbreaks, fungi outbreaks, vector/host outbreaks. Degraded sanitation, scavenger collapse, biomagnification (including toxins like ciguatera). Phytoplankton regime shift.
To get a sense of their size: Storm surges can kill in the 100,000’s, flooding can kill 1-2 million, scavenger collapse killed 100,000s. Degraded sanitation kills a few million annually, diseases kill millions annually, snake bites are about 100,000 annually. We would need to check how many were excess deaths caused by ecological amplification/failure, compare the damage from things like permanent lost productivity, and estimate how large these could get in worst-case scenarios. For now, it looks like disease burdens are probably going to be the worst ecological catastrophes.
There are three main proposed avenues of ecological-caused human extinction risk: 1) Resource depletion, failure of critical life systems, and cascading collapse. None of these pose a serious existential risk. For resource depletion, there are thousands of years of resources left with multiple alternatives we could switch to. For critical life systems failure, there are so many redundant species and so few species are needed to perform vital ecosystem services that we are thousands of years away from losing them all to extinction. For cascading collapse, there isn’t evidence of compounding synergistic effects from totally collapsed landscapes nor in regions of severely depleted biodiversity. Losing even a large number of species simply isn’t a realistic, pressing threat to human civilization -- so people should stop acting like it is!
This post probably makes it seem like we are anti-conservation and think biodiversity isn’t worth protecting. That’s not true! The whole project of EcoResilience Initiative is to find the best ways to protect biodiversity, because we think nature is incredibly valuable and underrated. Nature makes our lives richer and fuller, and the earth’s billion-years-long legacy of biodiversity is, considered as a whole, one of the most beautiful things in the universe. It would be a shame to let all that beauty and complexity be eroded away by species extinctions during this tumultuous era of industrial civilization -- instead, we should find good ways of preserving nature so we can experience a more flourishing future.
This post felt like a tedious but necessary prerequisite for what I think is actually more exciting -- detailing what I consider the *real* top reasons to protect our planet’s biodiversity. If you’re looking forward to that post too, then consider [subscribing] for our upcoming post in the sequence below!
* * *
This is part of a sequence on where the value of biodiversity comes from:
People really care about something they call nature
Nature's value mostly doesn't come from present-day benefits to humanity
And ecological collapse is not an existential risk
The real value actually comes from long-term flourishing.
Conservation in the next century is going to look a lot different than environmentalists think
About 0.01%-1% or 5,000-100,000 species according to my estimate.[5]
I’m not aware of other kinds of ecological risks, but I would be interested to learn about other examples
To get a rough global estimate of required biodiversity for ecosystem services, I multiply each species required count from this table by the number of global biomes (85-500) and get ~5,000-100,000 (0.01%-1% of total extant species). Total biomes are somewhere between 85 (at the Formation level, which would be minimizing global species) and like 500 (at the Division level which would be using locally thriving species). Totaling that up comes out to somewhere between 7,480 (0.086% out of all extant species) and 81,500 species (0.94%) to support global ecosystem services. Flaws with this estimate: There are unlisted ecosystem services. I’m overcounting habitats since biomes like “ephemeral salt lakes,” “ground water” and “mud plains” would provide more limited sets of ecosystem services. Some species could fulfill multiple ecosystem services. Some species could fulfill multiple biomes. Supporting ecosystem services would be needed. I think this estimate is really low, but far more than required for a handful of humans to survive.
There are multiple steps to nitrification and the most limited one is Ammonia oxidation which is provided by only three guilds: AOA, AOB, comammox. Of those, anammox is only six genera, one phylum.
To get a rough global estimate of required biodiversity for ecosystem services, I multiply each species required count from this table by the number of global biomes (85-500) and get ~5,000-100,000 (0.01%-1% of total extant species). Total biomes are somewhere between 85 (at the Formation level, which would be minimizing global species) and like 500 (at the Division level which would be using locally thriving species). Totaling that up comes out to somewhere between 7,480 (0.086% out of all extant species) and 81,500 species (0.94%) to support global ecosystem services. Flaws with this estimate: There are unlisted ecosystem services. I’m overcounting habitats since biomes like “ephemeral salt lakes,” “ground water” and “mud plains” would provide more limited sets of ecosystem services. Some species could fulfill multiple ecosystem services. Some species could fulfill multiple biomes. Supporting ecosystem services would be needed. I think this estimate is really low, but far more than required for a handful of humans to survive.
To get a rough global estimate of required biodiversity for ecosystem services, I multiply each species required count from this table by the number of global biomes (85-500) and get ~5,000-100,000 (0.01%-1% of total extant species). Total biomes are somewhere between 85 (at the Formation level, which would be minimizing global species) and like 500 (at the Division level which would be using locally thriving species). Totaling that up comes out to somewhere between 7,480 (0.086% out of all extant species) and 81,500 species (0.94%) to support global ecosystem services. Flaws with this estimate: There are unlisted ecosystem services. I’m overcounting habitats since biomes like “ephemeral salt lakes,” “ground water” and “mud plains” would provide more limited sets of ecosystem services. Some species could fulfill multiple ecosystem services. Some species could fulfill multiple biomes. Supporting ecosystem services would be needed. I think this estimate is really low, but far more than required for a handful of humans to survive.
These are some of the claims made by large and reputable environmental organizations: “Biodiversity is earth’s life support system.” “Nature gives us a habitable environment, we rely on clean air and water.” “We depend on nature for survival.” These claims are phrased to imply extensive environmental actions are important for human survival, which is not actually supported.
Most water treatment plants are chemical and physical processes. This is because biological processes are slower and less controlled.
The planetary boundaries say we have already crossed this boundary, at losses of "10 extinctions / million species years." The planetary boundaries represent boundaries past where we "do not know," not when we "will likely cause serious damage to civilization." I’m not even sure if the rate of extinction boundary is helpful because collapse risk would depend on how many species total are left, not the rate of decline?
Natural salt flats, sand dunes, rocky alpine, and taiga forest all have very low species diversity. Other examples are tree plantations and farmland with monoculture crops, and cheatgrass invaded sagebrush habitat (reduced down to 8 species of plant). These are not "uninhabitable" due to low biodiversity although they may be physically inhospitable. They are not collapsing dustbowls with no water and oxygen.
