The Great Simplification with Nate Hagens - The Population Problem: Human Impact, Extinctions, and the Biodiversity Crisis with Corey Bradshaw

Episode Date: August 14, 2024

(Conversation recorded on July 25th, 2024)   Show Summary:  Human overpopulation is often depicted in the media in one of two ways: as either a catastrophic disaster or an overly-exaggerated concern. Yet the data understood by scientists and researchers is clear. So what is the actual state of our overshoot, and, despite our growing numbers, are we already seeing the signs that the sixth mass extinction is underway? In this episode, Nate is joined by global ecologist Corey Bradshaw to discuss his recent research on the rapid decline in biodiversity, how population and demographics will change in the coming decades, and what both of these will mean for complex global economies currently reliant on a stable environment. How might the current rate of species loss result in a domino effect of widespread and severe impacts on the health of the biosphere? What are the key factors driving changes in population growth, and how do these vary across different countries and cultures? Could we stabilize these trends and achieve a sustainable balance between biodiversity and human population through targeted policies and initiatives — and how much time is left to act?   About Corey Bradshaw: Corey Bradshaw is the Matthew Flinders Professor of Global Ecology and Director of the Global Ecology Laboratory at Flinders University in South Australia. He is also the head of the Flinders Modelling Node of the Centre of Excellence for Australian Biodiversity and Heritage. He has completed three tertiary degrees in ecology (BSc, MSc, PhD) from universities in Canada and New Zealand, and a Certificate in Veterinary Conservation Medicine from Murdoch University. In a world where human activity has precipitated the current Anthropocene extinction event, he aims to provide irrefutable evidence to influence government policy and private behavior for the preservation of our planet's biowealth. He has published over 300 peer-reviewed scientific articles, 13 book chapters and 3 books, including The Effective Scientist and Killing the Koala and Poisoning the Prairie.  --- Support Institute for the Study of Energy and Our Future Join our Substack newsletter Join our Discord channel and connect with other listeners --- Show Notes and More  Watch this video episode on Youtube  

We're looking at a series of death by 1,000 cuts in many cases of the combination of a rapidly changing climate, but just the expansion of humans and their needs. I mean, even if we live in a completely eco-friendly way and have very low per capita consumption, and we live, you know, not in this high consumption manner that we have today, we completely change the economic system or it's forced upon us by collapse. There's still so many of us. We still eat. and we will still hunt and we will still take resources until they're gone.

And then subsequently, we will be of lower density. I don't think humans are going to go extinct anytime soon, but there will be a point when the Earth's carrying capacity, and I think we've surpassed that by several decades already, will no longer be able to support the numbers that are there. You're listening to the Great Simplification. I'm Nate Higgins. On this show, we describe how energy, the economy,

the environment and human behavior all fit together and what it might mean for our future. By sharing insights from global thinkers, we hope to inform and inspire more humans to play emergent roles in the coming great simplification. I would like to welcome Australian Professor Corey Bradshaw to the program to discuss his latest research on the sixth mass extinction as well as human population demographics. I would like to caution viewers. This is not an episode for the faint of heart. If I was still teaching, I would probably have to issue a trigger warning.

It's very intense on some of the topics on climate, mass extinctions, human population. But you all show up here to learn about the world we face. So it's an excellent conversation, and I hope you listen to it, but it's intense. Corey Bradshaw is a Matthew Flinders fellow in Global Ecology, at Flinders University in Australia. He's published over 300 peer-reviewed scientific articles. He's also the director of the global ecology laboratory and a chief investigator in the Arc Center of Excellence for Australian Biodiversity and Heritage.

Corey's research is mainly focused on global change ecology, how human endeavors and climate fixations have altered past, present and future ecosystems. This episode is densely packed with information, and while it does paint a daunting picture of what we face, it's my continued belief that to address the situation we face, we have to understand what we face and all that it entails. That being said, I greatly enjoyed this conversation with Corey, and I've asked him to be the anchor on a population roundtable in the near future. This was one of our most potent episodes. Last but not least, I would like to remind listeners that we are not a monetized podcast. So one of the biggest ways you can support us is by following and subscribing on whatever platform you used to listen. Additionally, if you'd like to donate to our organization, please use the link in the description.

All donations are tax deductible and go directly to our operating costs. And we appreciate your continued listenership and support. With that, please welcome Corey Bradshaw. Professor Bradshaw, good to see you. Good morning. Oh, good evening. It's good evening for me. Good morning for you in Adelaide, Australia. So you lead a very busy academic life, publishing papers, teaching articles, book chapters on a wide range of ecological topics. We have a lot of natural scientist colleagues as mutual friends.

And today I'd like to focus on the topics of biodiversity, mass extinctions, as well as human population and human demographics, which are among your specialties, especially with regard to two recent papers of yours, which we will highlight in the show notes for people to look them. But before we dive into all that, maybe you could share with our viewers your background. What inspired you to be a research ecologist? Oh, I have a very weird background, actually, in some ways. I didn't go through the normal channels. Which seems to be the case for almost all ecologists that I... Yeah, I suppose I guess it's probably normal from that group of people. But despite my accent, I actually grew up in Western Canada, and my father was a fur trapper.

and I spent a lot of time in the bush as a kid. In fact, the first time I saw a city, I was 16 years old. Yes, I've spent most of my life in Australia, but that's how I started. And growing up with a trapper father puts you in contact in a rather consumptive way, but puts you in contact with a lot of nature. And I think that's where it started. I was interested in how animals behaved and how they adapted to. their environments and I saw it sort of the the gritty end of that.

But over time, I realized that even people like fur trappers who, as again, are quite consumptive in their use of nature, in that time, they were actually one of the largest lobbyist groups for reducing deforestation rates because you cut down the bush and there's no fur to trap. There's no fair animals to trap. So there was a conservation ethic underneath that that had an ulterior motive, but it was actually quite efficient in convincing government that they shouldn't just cut everything down. So that was my introduction, sort of into the deep end of conservation.

But on that, just to pinpoint that, they weren't trying to conserve. on behalf of nature, they were conserving because they wanted something for their own bottom line profits. So it was still in the name of profits and progress, etc. Absolutely. But, you know, if you don't have a healthy ecosystem, you don't have animals to trap. And so they were very strongly vocal about keeping those ecosystems in some form of balance. And, you know, everything from bushfire prevention to logging to overhunting. And, and, and, and, you know, and even introduced species. So not to age you,

but I assume you were born in the late 60s, early 70s? 1970, yes. So how does, in British Columbia? Yes, yeah, in the Rocky Mountains. So how does the megafauna today relative to the early 70s and the things that were trapped?

Yeah, not having lived in Canada for a long time, it's difficult for me to say exactly what's going on. But my understanding is that a lot of those animals are still doing relatively well. I mean, despite all of the other declines everywhere else. But a lot of those places that were trapped, as far as I know, still have the tree cover, which is probably one of the main things. I mean, habitat loss being one of the principal drivers of biodiversity decline.

Now, things have changed, obviously climate change, things are warming up, distributions are changing. So I can't speak with any authority about a lot of the species, but I haven't been aware of at least any extinctions in those regions. I was in Yukon territory a few years, and that's one of the few geographical areas in the world where the historic relationship of megafauna biomass to humans is still largely what it used to be. I suspect it's very similar. I was actually just in Canada, in Quebec, actually, the last month, and I was still quite surprised

how much tree cover is there. And yes, a lot of that is secondary growth from, over exploitation centuries ago, but, you know, there's still some very beautiful and very productive areas. So I'm still, I'm pleased to see that. So carry on with your story. Sorry to interrupt. After that, I was lucky enough to get a scholarship to go to an international school on Vancouver Island. And that really sort of started my pathway on the academic side of things. I did the International Baccalaureate, which is a kind of a bridging program in international curriculum that really focuses on developing your own capacities. And I was in a beautiful

spot outside of Victoria on Vancouver Island in this little bay. And we did scuba diving. We did sailing. We had our lab. It was right on the water. So we had lots of marine components to the ecology courses that I was taking. And I really sort of got hooked on the academic side of things and realized that a lot of my knowledge was actually applicable, and perhaps I could even turn it into a career. So after that, I ended up going to do my undergraduate at the University of Montreal in Montreal, and that had a strong ecological stream.

They're very well known for their, especially their plant ecology and a lot of entomology. And so I became very astute in the, in, in, in discovery and taxonomy of the Laurentian region around sort of central Quebec. And that just sort of precipitated into a master's and eventually a PhD. And I decided I'd leave Canada permanently around then. So I went to New Zealand. I did my PhD at the University of Otago in Dunedin.

And I saw some pretty amazing spots around New Zealand. Got to some very remote areas. I was working on fur seals at the time. Nothing terribly scientifically interesting in retrospect, but it got me to some really cool places and I'd sort of cut my teeth in the mathematical side of things. And I guess from there, that's where I really became probably more of a computational or a modeler, computational biologist or a modeler.

And these days, I'm, you know, back in the day, I used to spend nine months of the year in the field and now I'm mostly coding and listening to death. metal when I do it. And that's how appropriate given the topic. Okay. So I had earlier this year a science journalist named Peter Brannon on who talked about the five previous mass extinctions and many minor extinctions.

Can you just give me a bird's eye view, speculate, where are we with respect to a sixth mass extinction event? What is the stance based on your lifetime of scholarship and research into that topic? Yeah, I've written about that quite a bit recently and it's good to understand the deep time aspect. In fact, I'm doing a lot of deep time paleontology these days, even back to the Ediacaran. So over 500 million years ago, been just working on a lot of Devonian stuff. So in the 360 to 400, 400,000, million year range. And how do we know stuff from 360 million years ago, just from fossils?

Yeah, pretty much. It's in the rocks. You've got to be a bit of a geologist to do good deep time paleotology, all in the sedimentary material. And the precision, I mean, the, the preservation in some of these Lagosteta, these amazing preservation sites are just gobsmacking. So you can, you can really track the evolution. I'm working, I've just published my first paper on the evolution of sealicants, for example.

And the history of the record there is, it's astounding, goes back to over 400 billion years ago. And we can pinpoint very minor evolutionary changes. And, you know, even stem tetrapods right up to, you know, the emergence of the first reptiles and amphibians. So you can pinpoint the evolutionary trajectory of celocants when they had adaptations and were better swimmers or whatever else just from using today's science. Yeah. And we know when things went extinct. precipitously, and that's how we really track these mass extinction events. And a mass extinction event by itself is a little bit of an arbitrary designation. So it's at least 75% of species

going extinct within about two and a half, three million years. Now, why that? Because those are the big ones that sort of stuck out. It is arbitrary. There are lots that are fewer or lower proportion of extinctions, 50, 40, 35 in that range. And the time frame, you know, two and a half, three million years doesn't sound like it's a mass extinction that happens suddenly. It's not like the sort of the dinosaur bolide impact and the Cretaceous. But, you know, in geological speak, that's an eye blick. So these are rapid extinction events. Yes, they can take millions of years.

Now, so there's a lot of smaller extinctions, in fact, probably well between, somewhere between 20 and 40, depending on what sort of threshold you decide to use. and they occur quite regularly through the geological history. Regularly as in they're frequent or regularly as in they could be predicted time-wise, time-interview. Yeah, we can't predict them. That's the thing. It's a very, people have looked for patterns, and there are some suggestions, perhaps some sort of cyclicity in the orbital relationship in the solar system about, you know, how far we are from the sun and various other. things. But if there is anything going on, it's, it's, um, it's very minor compared to the randomness

of these events happening. But how many of those 20 to 40 minor extinctions and the five big ones were related to carbon pulses? Probably quite a few. I mean, a lot of the early ones, of course, were only marine. So these were, um, lack of oxygen and, and even temperature related, uh, changes in, in chemistry. of the ocean. And these are usually shallow seas where most of the life was concentrated around the edges of continental masses. And so if you get these even subtle changes in atmospheric concentrations of different gases or changes in the saturation point of oxygen in the water, you can precipitate these huge die-offs that can span the entire globe. And we see the evidence

of that time and time again throughout the entire geological history. So with that caveat, how likely is it that we're headed for a minor or mass extinction in coming hundreds of years, given what's built in? Yeah, well, this is some of our colleagues and I've argued quite strongly that we're actually in the sixth mass extinction now. Now, have we achieved a 75% reduction from some previous baseline, whether that was, you know, the onset of the Anthropocene? And that isn't even really well understood or at least there's no. There's no agreement on when that might have happened. But if we go back even to the sort of the fertile crescent, the development of agriculture and humans 12,000 years ago, give a take,

we took that time frame as a sort of a baseline. We haven't achieved a 75% reduction in biodiversity. That is number of species or even other metrics of biodiversity. For example, the distinctiveness, the evolutionary distinctiveness of species. but if you look at the extinction rates that happen between these mass extinction events, and again, we can estimate those quite well from the fossil record, what we have even just what we've recorded, not taking into consideration the species that we miss, because many species, of course, have very small ranges, they're very tiny,

they live in a very cryptic lifestyle, and most extinctions actually go unnoticed until well after they've occurred. So even if we just look at the ones that we definitely know gone extinct that we've observed, we're looking at an extinction rate that's about sort of an average of about a thousand times the rate that occurs between these mass extinction events. That's what we're in now. And everything that we look at points to the fact that it's perhaps even larger than that. So while we're not, we haven't achieved that threshold yet, we're on the way.

And even more strikingly is that it's not going to happen in two and a half million years. It's going to be a century scale event. So this is potentially the largest mass extinct. I'd say the most important or the highest magnitude mass extinction event that has ever occurred in the history of planet Earth. It's happening now. We're in it. But it'll take some time to precipitate fully. For more reasons than one, it's also the high, before this mass extinction began, you know, let's just book,

Mark, 20,000 years ago, we were at the highest level of phylum genera species diversity ever from the scientific record, right? Yeah, if you look at just total number of species, that's true. If you look at phylogenetic diversity, so the uniqueness, the evolutionary uniqueness, no, actually we achieved that in the Cambrian. So going back 540 million years ago. So we call that disparity versus diversity. So there was more evolutionary and uniqueness.

Listen, evolution is this kind of weird things pop out that work for a while, and then they don't seem to work as well as some others. And so they sort of drop off the scene and then other things come up. For example, the placoderms, the bone-plated fish that are, you know, don Colostis and, you know, those massive bony-plated armored fish that you see sometimes in museums or even in film, they just were gone at the end of Devonian. and they never reappeared. Whereas things like silacanths, which are a very ancient, ancient fish, lobefin fish, they manage to survive right through to today.

So some things manage to work and other things don't. You know, a lot of people think that evolution is this process of constant sort of perfection and adaptation to some pinnacle or optimum. It doesn't work like that. It's actually the opposite. It's evolution is a penalty.

So if it works, fine. Evolution's not going to really screw with it. but if it gives a slight disadvantage, that's when it gets knocked on the head. And it might, that form, that particular form might never reappear again, or it might form in another different way.

For example, the evolution of eyes. That's happened in five or six different ways through different groups of species that have absolutely no relationship to one another. So there wasn't an eye that evolved somewhere and then all the eyes after that came from that single ancestor? No, it happened about four or five different times. Wow.

That's kind of cool. So there's lots of examples of that through morphology. Now, I'm not a paleontologist, so I'm talking a little bit outside of my area of expertise, but I do work closely with a lot of paleontologists. I do know that blue eyes were

epigenetic, epigamic, which means sexual selection preferred mutation not that long ago, and all the people in the world that have blue eyes did come from one person who had blue eyes, not that long ago. Yeah, I'm not sure if this is correct. but I was under the impression, too, that there was a link to Neanderthal genes associated with that.

Also, also ginger hair. So as it turns out, I had my DNA tested and I'm quite high on the Neanderthal scale. I am too. I am too. Neanderthal bros. United. Yeah. Well, it's funny.

Corey actually means caveman in Scottish. So works really well. Yeah. So I'm going to talk a lot about extant. and biodiversity and such. But finishing this intro to the topic, of course, the measurement and the impact and the data on mass extinction and species, both their population sizes and the number of species, our system is going to impact them in a backloaded fashion.

because while energy surplus has allowed us to expand around the planet and like you said earlier, the places in the world that have their forests removed, obviously are going to lose megafauna and insects and birds and other things. But what happens on the downslip of the carbon pulse if we have to go back in an Easter island sort of way and use forests for timber, et cetera? So, you know, we're impacting climate and habitat. on the way up, but we're also going to impact it on the way down. So my fear is that, you know, the animals that are very remote from human habitations will have a reprieve,

but the ones closer are not, especially the megafauna in Africa and places that are near economically poor areas. I don't see how they're going to survive. I'm going a little off tangent, but do you have any opinions on that? Yeah, no, I couldn't agree more. We're looking at a series of, you know, death by a thousand cuts in many cases of the combination of rapidly changing climate, but just the expansion of humans and their needs. I mean, even if we live in a completely sort of eco-friendly way and have low, very low, per capita consumption, and we live in, you know, not in this consumptive, high consumption matter. that we have today, we completely change the economic system or it's forced upon us by collapse, then we're still, there's still so many of us, and we still eat, and we will still hunt and we will still take resources until they're gone. And then subsequently, we will be of lower density.

I don't think humans are going to go extinct anytime soon, but there will be a point when there's the Earth's carrying capacity, and I think we've surpassed that by several decades already, will no longer be able to support the numbers that are there. So there will be mass die-offs, there'll be warfare, there'll be natural disasters, and life per se, for a lot of people, will not be that pleasant. So we'll regress to those sort of perhaps even neolithic kind of times. That could be a century scale thing, but it's unlikely just given our numerical dominance that will go extinct right away. But humans are a flash in the pan in an evolutionary sense anyway. So, you know, we're not here for a long time.

We're going to talk about some, some dark things, I suspect. But let me throw in a little rainbow of sorts. You said that these mass extinctions happened in geological flashes of time over two or three million years. And there were 20 to 40 of them. So over 500 some million years, there were these very two, to three million year periods of mass extinction. And yet, up to 20,000 years ago or the Neanderthals, 40,000 years ago, we had the most biological diversity ever on the planet. So things do recover

on Earth, including an abundance of flourishing of life. So whatever happens in this six maths extinction, well, maybe not whatever happens. There could be nuclear war and a whole lot of confluence of events. But things. Things will evolve and there will be new life, maybe not complex life like dolphins, apes, and humans. But can you give us a bright story before we talk about some of the other constraints? Yeah, just given the complexity of life and the fact that we've gone through these dips, these huge dips in diversity over many, many hundreds and millions of years, it gives me

actually a lot of comfort, ironically. And I will quote from Paul Ehrlich here, who I just saw last week, actually. I passed through California on my way back home. And he always says, you know, the planet's fine. It's not in trouble. Life isn't in trouble. Humanity is, but life itself. So after a mass extinction, it opens up millions of new ecological niches

that are exploited through basically the trial and era of evolution. change. And so extinction begets speciation. We always see the massive pulse and speciation and even the rate of evolution increases after a mass extinction event. So life will persist until the sun explodes and wipes out earth entirely from the solar system. And that's several billion years down the track. So we don't have to worry about in the immediate term. But life will pretty much always persist on the plant. Like you said, will another sentient species emerge from that? It's possible, but I tend to look at our big brains and our sentience as merely one of these disparity forms that have come out that provide an interesting chapter in the history of life, but aren't necessary for life to

persist in any sense whatsoever. There's nothing of high value that we can attribute to sentience per se. from a life perspective, it just happened. And we're using it to our advantage, but ultimately to our disadvantage. Do you think there's other planets out there that have life and complex life and oceans and biodiversity? I think it's pretty much a statistical given. Just the sheer immensity of our own galaxy, let alone the entire universe, that there's not some other form of life out there would be almost infinitesimally, a small probability. And so being a numbers guy, I can't accept the fact that there wouldn't be life.

Is it in a microbial form or something analogous to that? Is there a complex ecosystems? Well, I suspect there would be quite an array of different types of systems. I suspect probably the most common form of life in the universe would be microbial. And that probably in most cases wouldn't get much beyond that. In some cases, in the rare cases, you might actually get ecosystems established and some sort of trophic relationships between different species, whether there's the opportunity for this weird sentience experiment that evolution can kick up is entirely an open

question. I tend to think probably not. But if you went just on the probability, I'd say that, yes, plenty of life out there, but also on the same probability framework, the massive distances preclude us ever from discovering it. So if we do that... do discover life elsewhere, it'll be a big fluke, and it'll only be because it's next door. In a galactic sense, yes. Ethically, I think we have to treat this planet as the only place that harbors complex, sentient life, because that is sacred. I mean, I'm getting beyond the science, but, you know.

Well, we don't have any evidence to the alternative yet. So, I mean, if you're just playing the numbers, Of course, it makes sense, but we haven't a sample size of one, and that's the planet Earth. So let's dive into your work. You have a lot of your work looks at the impacts of co-extinctions and the overall rate of extinction and biodiversity. I don't know what a co-extinction is. Can you explain that and why it's important and relevant? Well, I'll take you back to 2017 working with a colleague of mine, Gioani.

Strona, who's now at the joint research center of the EU. He's based in Italy, obviously, an Italian name, good friend, and one of the best computational ecologists I've ever met. Well, we were sort of discussing a paper that had come out saying that tardigrades, the little, you know, water bears, the tiny, the multisullio, obviously, but if you've ever seen a photo of a tardy grade, they're the cutest little things, they've got little claws and little round bodies like La Mishlin Man and there's many different species and they exploit a lot of niches in the soil and then the litter layer. And there are immensely resilient little dudes. You can

boil them, you can freeze them, you can shoot them into space and they just go into this little cocoon and they can survive all sorts of extremes. And so the point of this particular paper was that no matter what happens on Earth, you know, a comet hits us or, you know, nuclear war or whatever, at least we're going to have tardy grates because they, physiologically, they're little juggernauts, the amazing little things. The second favorite creature on planet for me. I have to ask what the first thing is done. Oh, well, velvet worms.

Velvet worms. No, they're the coolest. They are the bridge between the true worms and arthropods. and they have the coolest hunting technique on the planet. What they do is they have two little siphons on the side of their mouths. And when they detect prey, they spit this kind of gluey mass and siphon it all out and just envelop their prey in this gooey mess. And then they just sort of suck it all in and eat the thing that's attached in the glue.

Yeah, absolutely amazing. I now see why you like death metal. Yes, weird things. like weird things, but, you know, I'm a classic geek scientist, so there you go. Anyway, Okay, water bears. Back to tardy grades. Yeah. Tarty grades. So we looked at this paper and went, and as ecology, we said, well, that's all fine. You know, they are resilient. And if you take them out of the system and you can do stuff to them, fine. But that's not actually how ecology works. Ecology works in the relationship to other species in the system just as much as it does to the

physical environment, the temperature, the water availability. So the food, really, is what drives ecological systems. Now, you can be really resilient to extremes and temperature and precipitation and so on and so forth. But if you have nothing to eat, you die, right? It's pretty clear. So everything eats something else or everything is related to something else. Think of parasites and their hosts. Without the hosts, the parasites can't survive. You think of flowering plants and their pollinators, just a bee and a flower. Without the flower, the bee goes extinct and without the bee, the flower goes extinct. Predators and prey, you know, you let your cat out at night and it eats all the birds and maybe some rodents. Without, you know, the prey, the predator dies. And so,

there's all these relationships that exist. And it gets more complex than that. There's a lot of different symbiosis, you know, plants growing on other plants and, you know, these, these hyper-specialized relationships. So if you look at a species in isolation or in vacuum and you say, okay, it'll survive, yet you fail to take into consideration all of its neighbors and all the species interacts with, then you're going to vastly underestimate what the total extinction rate might be from some sort of disturbance. So we call these dependencies in an extinction sense, if one goes extinct and then things depend on it, and no longer have that thing to depend upon, then they will go extinct too. These are secondary or co-extinctions. So you might have like a,

maybe this species was over-exploited, maybe it was a prey species of something else. And the predator over here goes, oh, I've got no more food. If it's specialized on this species that no longer exist, it drops off the perch. And that can cascade throughout an entire system. We have something called trophic webs. People call them food webs or food. food chains. That's a simplification. So you get thousands of species in a community and they'll interact either directly or through these chains or relationships. So one might eat something and then that's being eaten by something else and that's being eaten by something else and so on and so forth. So you can actually get this key species down here that a lot of things depend on. If it drops out,

then all of these things, some can rearrange, some can eat other things, but a lot of them are specialize so they drop out and then all the different relationships to all those other species that depend on it will then also precipitate these changes we use network analyses we actually use the same computer techniques we do to analyze you know internet relationships we do the same thing with ecological networks so i'm sure you've seen this uh short animated video which lizzie will find and put in the show notes that i used at my uh at my class which shows you show you a relationship between ants and plants and how there were certain ants for certain plants and sometimes they had seven or eight others.

And then you saw if there was a little drop in the species of ants or plants, there was not much of an impact, but the more of a drop than it cascaded through the ecosystem. Yeah, and that's another term we use, extinction cascades. And that's been known for quite a long time. But let's come back to Tadigrades in this particular paper. So what we did is we actually developed these massive virtual worlds of interrelated, you know, virtual species. So these, we're talking computer games, essentially. And we coded these large, again, it's models, so they're simplified systems.

But we try to get something as ecologically realistic as possible. And then what we did is after we established all these different relationships, we then took out species. So first we did it sort of at random. And then we looked at these cascading effects. effects through its system. Then we tried to play God a little bit and we went sort of all evil and we took the most important species from those ecosystems. So those are the ones with the most connections. And then we took those out first. We, you know, virtual extinction. Those would be really low on the trophic pyramid as in their food for a lot of other things.

You can get predators that actually have many different prey and they keep different prey species numerically in check. So without the predator, the prey go on to overshoot and destroy the ecosystem. Exactly. And then all these other things that depend on that ecosystem will die out too. So it's not necessarily the lowest trophic levels or the ones that are being eaten by everything else. And it's true, though, that plants are an key component of these systems.

So we'll come back to plants later. But then we also did things like we took the next most important and so on and so forth. And then we heated up this. system and we looked at thermal tolerances. So how much could you heat a species up until it died? You know, some species a little bit above their temperature range and they like totals, they die in instantly or- You weren't heating up the species. You were heating up the environment in which the species live. We were heating up on virtual earth, yes. Yeah, okay. But we coded in all of these different thermal tolerances because actually there's huge databases on what species, what type of

species can handle both in terms of upper range and lower range. So cold, and hot ranges. And once they exceed that, you know, there can be behavioral adaptations. There can be changes to their distributions. You know, they can move latitudinally to get the most optimum range. That's actually what's happening. But if we heat the system up and say, okay, once you exceed this threshold, you die. Or you, you know, we did a cooling one as well, just as a point of comparison.

And what struck us was two things. when you don't account for the secondary extinctions, if you just look at what's causing the primary extinctions from the exceeding the thermal tolerance, compared to if you take into account the co-extinctions, you can underestimate overall extinction rate by about 10 times. In other words, yeah, you have 10 times more extinctions

than you would otherwise have just from the primary extinctions. So most of our ecological climate system science is using too narrow of boundaries and not the precautionary principle. Everything is way, way, way more connected than the common narrative. Yeah. Now, that was a very theoretical sort of heating the planet to 20 plus degrees or cooling it minus 20 degrees and seeing these massive changes. But the other striking thing about that work was that when we took, when we,

we played evil and tried to crash the system as quickly as possible, and compared that to the heating trajectory, they were almost identical. So if you were to choose the disturbance that precipitated the most extinctions through extinction cascades, it would be heating. It's not cold. Yeah. So it's quite depressing. Now, that was a, there was a very big theoretical paper in terms of how we structured it. But we then did a subsequent work and we looked at heating over the coming century and we took a very, a much more ecologically realistic virtual earth.

and we created, yeah, it was geographically explicit, so we covered the entire planet, and we only looked at terrestrial to start with, but we basically looked at within the timeframe of this century, the underestimate from primary extinctions is about 50%. So just in that with the next, you know, 70, 80 years, what's been predicted to go extinct by the end of the century, we're probably going to be at least double that.

Predicted by who? Well, predicted from the thermal tolerances of just those primary extinctions. So it's quite a bit of work. Because of the co-extinctions and the tardigrade effect that if that species is gone, then there's the food web implications. So is there such a thing as the inverse of that, a positive, a negative co-extinction that a species disappears and it's better for the ecosystems? Well, that's probably an open question in a lot of respects because, well, there's been some work on the influence of invasive species in potentially replacing ecological function in some of these systems.

So what I mean ecological function, let's say you'll lose a key predator. And then some other species comes in and takes that role in that ecosystem. It could potentially replace that and save the community from that co-extinction cascade. But in most senses, what we're seeing is quite the opposite. So you add in another species. And even though it might replace some of the ecological function, it's different enough to actually cause more extinctions. So we haven't actually seen evidence of that yet. Let's talk about insects.

I had a butterfly specialist Nick Haddad from Michigan State on, and he gave some just horrifying statistics on insects. So lay it on us, Corey. What is this situation? My understanding is that we're losing insect biomass 1 to 2% a year. And does that at some point play into your co-extinction thesis? Have you looked at that? Well, yes.

And no. The yes part is that from an ecological perspective, once the insects go, you're looking at a bottom-up effect. So we're talking bottom from a trophic perspective, who feeds on whom, that you could precipitate a lot more extinctions quickly. Actually, it's even below that. The plants are probably even more important because most insects are herbivorous, right? So they're eating the plants and then things eat those insects and so on and so forth. So we as ecologists, as the ecological community, probably never really expected that insects would be declining at the same rate as vertebrates simply because they have high reproductive rates. You know, one female can produce millions of eggs in one clutch.

They have adapted to almost every single niche, you know, the highest diversity. 50% of all animal species are beetles, you know, those kind of statistics that are, Just mind-boggling. 50% of insect species or animals species? 50% of all animal species are one order of insect, colioptera, which are the beetles. Wow. Yeah.

I mean, most of the biomass, terrestrial biomass on the planet is, well, plants, then bacteria, but then invertebrates. So most things, most things are insects on the continental scale. If you're not, if you're just looking at animals.

Well, insects, we take them for granted, like oxygen or water, but at one to two percent a year, if that number is even in the ballpark, you just, you're a numbers guy. That's 50 years and it's game over or less. And most of our ecological networks have pretty much ignored those lowest trophic levels, the plants and the insects. So our 10 times overestimation or underestimation of extinction rate is probably, being conservative because we haven't accounted for that insect and plant biomass change. So it's much, much worse than even our worst case scenarios. That's kind of the point of this conversation. And we never expected the insects to be at the same sort of extinction rates that the vertebrates are because of those life history traits that allow them to exploit these niches

quickly. But we're seeing that. Now, the problem is that we haven't been looking at insects as well as everything else. And the fact that they're so variable in time, you can get an explosion of cicadas or something. And then, you know, the next year, there's none. To be able to determine trends with really variable data like that, you need a lot of time. And research money and bodies and equipment and all that. And globally, it's actually quite controversial, the extent to which insect changes and reductions are happening. But everywhere that people have looked well, and it's only a handful of places, we're seeing these precipitous drops. And you'll, you know, you hear a lot of anecdotal information.

There's a lot of signs still to be done in this area, but the, the signs are extremely worrying. Let me, let me ask you this. Well, of course, where I live, uh, in the Midwest USA, I remember 40 years ago growing up, you'd have to clean your windshields off driving around. The windscreen analogy is quite commonly used. Yeah. Oh, well, it just because people remember it.

That, I mean, almost every one you talk. to notices that and there might be a lot of truth in that and it's just unfortunately we haven't actually got the numbers associated with those it's anecdotal it's not science but with the science so the living planet index uh i think was a few years ago said that we've lost around 70% of the populations of of animals um since the year 1970 globally um but that was really uh different on the area, like North America is only like 25%. Latin America and South America and parts of Asia were 70% and some places 90%.

What about insects? Does it follow the same sort of numbers or don't we know? Those are only vertebrates. The living planet index only looks at vertebrates. And that's, it's major limitation. It's a very good index. As you say, it's so highly spatially variable. We have nothing like that for insects.

And people are doing a lot of work to try to get to something like that. But we just, that's a big unknown, unfortunately. It's probably in that same sort of category of, in terms of reduction of individuals. And that's really what the Living Planet Index is. It's how many individuals in populations. So are you, as a scientist who this isn't your core thing, but numbers are, Do you feel confident that one to two percent loss in insect biomass annually recently is an adequate description of what's going on? I think that's plausible.

I think there would probably be high uncertainty around those numbers. And the other component about because of that rapid life history of many insects, in many cases, they could potentially be driven to extremely low abundance and then rebound from those, whereas that would just knock out any vertebrate. We don't really know what inbreeding depression, how that affects a lot of insect species. Most of our work on genetics and inbreeding depression. And that's basically, if you have a very small population, the chances of having a sexual relationship with your neighbor increases the relationship between them because they're probably going to be kin. And there's all sorts of jokes and movies and everything made about that. Mutiny on the Bounty, same sort of thing, post-mutuant. you on the bounty, there's inbreeding, it's not good for species. And we know what these

inbreeding coefficients are for many vertebrate species. And some species are extremely susceptible to it. For example, mammals and humans, we don't deal well with inbreeding. Other things like sharks seem to be relatively resilient to them. A lot of plants, they can happily reproduce vegetatively or clonally for a long, long time without no real observable impact. We don't know what happens with insects. I'm going to have to have you back because we haven't even gotten to the questions that I want to ask, so I'm still going to keep asking other ones. So there are other kinds of extinctions, right?

There's something called ecological extinction where a species no longer plays the functional role in its ecosystem, even though we still have, you know, a few hundred of them. I think there's 390 right whales left as an example. But then I wonder if there's a functional extinction where there might be 200 of these megafauna left, so the species exists, but it's so genetically inbred. I think a cheetahs come to mind that at some point they don't become healthy and there's not a viable enough gene pool. What is the science that that's all called?

and is that relevant to our story? Yeah, so this comes back to our inbreeding discussion. But basically when you get down to very small numbers, the chance of inbreeding increases dramatically. And what that does is it tends to reduce your genetic diversity. So how variable your DNA is across the entire chromosome. And in itself, it usually isn't a direct problem. Yes, you can get the expression of, for example,

what we call homozygous alleles that have both a dilaterious effect. And when they're expressed together, they can create all sorts of diseases or they can, you know, you might not grow a particular component of your body properly or you have a physiological, you're missing an enzyme that's essential for, for example, digesting proteins or there's a million different ways that can precipitate. but more commonly inbreeding depression doesn't have that direct what we call deleterious or lethal effect. What it does is just by virtue of having reduced variability in you cross your genome, means that when things change, there's less of a template to, or less or a smaller toolbox that you can then borrow from to adapt to that change.

And I'm talking on a generational scale, not an individual lifespan. man. So if things change, for example, climate and you're heating up, and you have, if you have a very healthy genome, you're genetically diverse in your population, there's chances are that some of those individuals in there were going to have the genetic capability to adapt their enzymes, for example, to deal with increasing heat and maybe increase your thermal tolerance. But when the population size is small and therefore your genetic diversity is low, you have fewer tools in your toolbox to deal with change. And so that really is what drives these long-term susceptibilities is that you have, even though things are getting worse, you have less adaptability. It's a little bit like

politics. You know, we have big more and more problems to deal with, but across the world, we're seeing the rise of conservatism and reduction of capacity to deal with these mounting problems. It's the same thing in genetics. And the irony is in the word conservatism is the word conserve. So getting back to insects, how important are pollinators and what's the story there? Well, you know, there's been quite a bit of back of the envelope calculation of the value of pollinators just to our cropping systems. For example, 80% of all of our crops require some form of animal pollination. And it's about 70% for all flowering plants. And most of that is from insects. And in fact, 50% of all of that pollination that occurs for our crops is provided by

one species. Apis Melifera, the European honeybee. Without that species, we would probably lose at least a third of our food production. Couldn't we use drones or such? Well, they've actually tried that. It's not very efficient. As you can imagine, if you're dealing with small flowers on things, it's extremely difficult to pollinate properly. So there have been estimates of what the net value worth of pollination globally, and it's in the trillions of dollars annually, and that's probably an underestimate, because we couldn't even do what insects actually do for us,

and mainly bees. So, you know, when you see things like hive syndromes where, you know, bees are being reduced to very small numbers, you get mites, all sorts of things that, compromise bee production. And, you know, in many parts of the world, including the U.S., much of the cropping is due to the fact that people move around beehives and allow for that pollination to occur. Without that, you would reduce your total crop yields by massive amounts.

Okay. That is an introduction. I'm sure we could have talked a lot longer on the details of the various unfolding extinctions or population declines in nature. but what's causing it? What are the biggest driving factors across the board on some of these issues that we've discussed? You mentioned habitat loss with forests. What else?

Well, the legacy of habitat loss basically from the expansion of, mainly from expansion of human agriculture. So, yes, we do also expand in terms of urbanization and just carving out a place to live. But most of the damages occurred through the expansion of agriculture. culture and much of that has happened since the 1950s because that's that's been the massive pulse we've gone from you know two billion to over eight billion in that time frame and so just the increase in the amount of land required to feed us has caused most of those extinctions in the trestrial realm obviously but we've also had

and that's probably the more proximate um cause of most extinctions but of course we have over exploitation, that just basically overhunting. So you take your bison example or your passenger pigeon or your great ork. You know, there's many, many examples of massive overhunting. Great orc? I didn't think those were real. No, the great orc. Sorry, it's my accent.

A-U-K. Oh, A-U-K. What is that like a big cow? No, no. It was a large seabird that populated most of the North Atlantic. And it was overhunted for mainly for its eggs and partially for the adult birds and its meat. And this is actually a really interesting story because while it was really widespread and not susceptible to, you know, small perturbations around here and there across its range, it got to such a small number. And the last colony was on a little islet off of Iceland.

And that eyelid blew up in a volcanic explosion. And that was the end of the species. that one explosion was the ultimate cause of its extinction, but the reason it went extinct is because its entire range had been reduced. So anyway, back to, we're saying these extinctions, over-exploitation, invasive species is probably one of the biggest contributors today, and that is via changing the dynamics of these systems. So they come in and they eat things.

They also out-compete things. change soil chemistry. They completely restructure communities in, for example, lakes and rivers. Could you give an example, a modern example of an invasive species that had a dilaterious effect on the existing species? Well, I'll give you a great example in Australia. We introduced cats and foxes to Australia, some 200 so years ago. And cats, when they were released here, went sort of woo-hoo and spread to all parts of.

of the continent and they are the principal driver for the highest mammalian extinction rate of any country in the world. Yes, Australia is number one. We have the highest rate of mammal extinctions globally. And it was mainly because of cats. Are they, you mean they're living in people's houses or these are wild cats? No, these are feral cats. These are, yeah, cats that have gone.

Also people in people's houses, but mainly they're wild, you know, what we call feral. So they've been released and they've gone wild. So they kill the mammals as well as birds, presumably. Yeah, birds as well. We have a lot of threatened birds because of, but the main effect has been small marsupials, small marsupial mammals, foxes to a lesser extent, but then we also have things like rabbits that have destroyed soil chemistry and topsoil erosion across the country. We have carp that have invaded our freshwater systems and we don't have a lot of

freshwater in Australia, and they've completely changed those ecosystems and precipitated extinctions of other fish species just by the sheer abundance, not just their predation. We have, you know, weed species that have overtaken vast tracts of forest, and they choke out native species. So they did, the list goes on and on and on. But this happened before humans. There were, I suppose, the speed at which new species could be introduced came on boats with humans. There were stowaway rats or whatever else. But these bursts of invasive species also happened before humans, yes? True. Yes. I mean, we tend to call them vagrants instead of invasive species per se. Just that's, I guess, just the lexicon. But things would

be blown off track, you know, a flying bird and managed to establish a small population somewhere. but it obviously takes more than one usually, get back to that inbreeding conversation we had earlier. But most of it is through commerce. Most of the transplanted species are through commerce, through shipping, through airplanes, through just people walking, driving. And you can get invasive species even within the same country.

One side of the country will have a completely different biota than the other side, and people will exchange those. And that can cause massive disruptions in those very delicate systems. Globally, invasive species cost our economies about $1.5 trillion annually. That's just the economics. How much do our economies cost the other species? Exactly. But just to show you that we also do a lot of work on the economics of invasive species,

and there are a massive drain on our global economic systems as well. Okay. Habitat loss, over-exploitation, invasive species. And now climate change. And now climate change. Of all of those, and climate change is already precipitating extinctions, climate change is overtaking all of that. Even at, even at one and a half degrees Celsius only, only. Oh, yeah.

Well, one and a half is a pipe dream now. We're looking at more like two to four by the end of the century now. This is the most realistic projections. And at one point, I, I, well, we could pick a number because like, like you said on, on the co-execision. and the vertical and horizontal relationships with everything, no one has a freaking clue. Let's just say that we stop at three degrees Celsius. What does that, just that number, let's speculate that that's where it stops.

You know, could be two, could be four, we don't know. Paint us a picture of what that means to the other non-human species on the planet in a few minutes. Well, again, without trying to get too predictive about proportions or anything, we're probably looking at least half of species on the planet going extinct within the time frame that's affected by that change. At three degrees Celsius. Yeah, yeah.

In the past, it was sort of predicted to be more like in the 10%, 15% range, but now, given that understanding of coextinctions, it's probably well above that. So I would say 50% would probably be in the right area. Do the average climate scientist who's looking at glacier melting and Arctic ice and other things, do they understand what you just told me? From an extinction perspective, probably not, but I think most climate scientists are shitting the dachs, basically. That every time we come close to understanding a projection, we, we, we, it's. exceed it. And so if you look at the predictions back in the early 90s to where we are today, we've exceeded everything. We're seeing these increase in pulses. I mean, what was it? Sunday was

the hottest day on the planet ever this Sunday. And then Monday was the hottest thereafter. So we're still being blown away by how conservative our models have been. And that's partially politics. And we can get into that about, you know, the IPCC and the fact that, that we've downplayed the severity of this because it's not politically palatable for most people. Even the language that the IPCC uses and is reporting reduces the certainty with which we report these changes. So most scientists, you know, they have a hard time getting out of bed in the morning when they understand gravity or the extent and the magnitude of these changes that are happening in their own lifetimes. So we're a depressed bunch.

Let me talk about that for a second, Corey. I host this podcast so I know these things. You obviously are an ecological researcher. You work on this every day. But especially for lay people around the world listening to this podcast, this episode, this can be a freaking gut punch. I mean, it is a slow unfolding, tragedy, horror movie,

how do you cope with that and keep your jovial attitude? And I mean, at some point is this helpful to tell people what's going on? 50% of species, if we are at 3 degrees Celsius, plus a whole lot of asterisk and other unknowns, I think we have to communicate, this is our world, our planet. And yet to some people, is almost too much to bear.

And I'm borderline one of them, to be honest. Yeah. And it's a perfectly normal response. And the ability to deal with change that you are incapable of altering, that's the other component. And there's actually an entire branch of psychology devoted to this. We can get into it a little bit. But basically the idea is that it comes back to Ernst Becker's book back in the

in the 1970s, it won the Booker Prize on the, basically the idea that people deny their death. It was called the denial of death. And how as an individual, you have aspirations, you have dreams, you have, you enjoy life, you raise families, you have, most people have this positive outlook on and achieving something. Yet for all that to disappear because you die, because we all die. And so we have this, we've built-in psychological denial of death. And that's why death is such a scary topic for most people. But now, let's magnify that to planetary death, or at least death of life.

So we can't even handle it on an individual level. So our little brains really can't handle the severity of the loss of life at this scale. So we become even more denialist. And in fact, it's cognitive dissonance, Red Lard. It is. It's a complete cognitive. is, and it's for our mental health that we do this. So I don't blame people for putting the head in the sand.

And as a parent, too, in fact, parents are the worst culprits because, you know, no matter what you do, invest in your children, you make sure that they eat well, you invest in their education, you teach them about life. And for all that to mean nothing that they're going to still be facing these horrors in their lifetime is almost inconceivable in the head of a parent that there's nothing you can do. to give your kids a leg up. Yes, there's some buffering from wealth and from education, but everyone's susceptible.

So that cognitive distance is even magnified from most parents' perspective. So you translate that to an entire population. You can see why people are ignoring what's going on and don't want to hear the story, no matter how much we beat our drums and say, look, it's bad. We have to tell the story, but we also have to realize that people's reaction,

isn't going to be right, we best do something then, because that's not how people respond normally. And I guess that's given me a lot of, it's turned my frustration into at least an understanding of our own behavioral responses to emergency. And yes, you can sugarcoat things and you can tell them that, you know, if we do X, it'll be maybe not as bad. And that's actually become my philosophy. If I can, if I get out of bed in the morning and the work I do even change, is one small thing for the better. I say the future is going to be shitty, but maybe I can make it just a little less shitty. And that's kind of my philosophy of life now. And you have to accept that it's going to be catastrophic, but how big of a catastrophe are we talking? Maybe we can limit

it's damage to some extent. And once you accept that, it's actually easier to do your work and to be not depressed about it. I mean, it's still depressing. Don't get me wrong. I've had a lot of therapy. I do a lot of exercise in martial arts to, you know, that's my yoga. You know, it's just yoga with violence. I listen to death metal. I mean, these are my escapism. I make wine, you know, I have my, I enjoy my family. I have my little dogs, you know, I do enjoy life.

So that keeps me functioning as a human being. But I have to face this every single day regardless. Let me ask you this. you were interested in animals and biology and ecology, you told us your academic history. I'm sure when you started out as a bright-eyed, bushy-tailed, non-tattooed, 20-year-old, that you were just interested in the science and the wonder and beauty of it all. But at some point between then and now, you understood the sixth mass extinction and the, you know, 3 degrees Celsius plus or minus, even if it's 2 degrees.

degrees. It's a huge deal for other species. Right? So this is unfolded during your own intellectual and emotional journey. Yeah. Actually, when I started out in academia, I really did not like conservation biology or even conservation biologists. I thought they were sort of the fringe of science and that these people were sort of worried for nothing and that the real science was more the empirical stuff. And, you know, I was, I was very much involved that, but the more I had started looking into it, the more I realized how wrong I was. And that, that was probably one of the most important sciences that we could possibly do. And that's what drew me into that. And then the more, I mean, yes, I'm applying the mathematics and I still enjoy the empirical aspects of it,

the scientific components. That's, that's really my passion. But you can't help but be affected by that mentally and emotional. It's impossible because we're like ambulance, you know, paramedics. We see death and destruction and maiming and injury and suffering every single day. And you talk to your average paramedic and, you know, they have a hard time mentally dealing with that every single day. You know, post-traumatic stress disorder from military people. You know, there's many different professions that have this kind of response. And we're just one of those.

So we've talked about animal extinctions, some mass extinctions. I want to talk about human population levels. and the impact of that and also policy. But let me ask you a difficult question, put you on the spot, just because I'm curious as to your philosophy on this. If you could push a button and every human in the world

could understand what you do about animal, insect, wild populations and climate change and what climate change is going to do to those, would you push that button or not? everyone would understand. That's what the button would do. Yeah, it would understand.

You couldn't affect their caring. That would be another button. But everyone got to understand it. Like, oh, I believe this is the case. Yeah, absolutely. I think, you know, information is nothing but an advantage. It's how you deal with that information is, is, comes the moral and ethical components. Education.

I'm not sure I would press it. I would press it for those people that have levers of power. I don't know if the average person, benefits from hearing this story. I'm open-minded to it, but I, I'm not sure because people are already at what's end with all their worries and, and everything else going on. No, I do see your point. And I can certainly understand that some people wouldn't be mentally capable of dealing with that. But I think the, the advantages would outweigh the disadvantages overall. I think if people actually understood. And especially their, their particular

relationship, their lifestyle relationship to healthy ecosystems and why we can breathe and why we're happy and why we can make money and why we can travel and why we can see beautiful and appreciate beautiful things, art being one of them. That's, you know, art, it comes from natural systems. That's why we embrace it. If that understanding was there that we can see the link to our own well-being, I think that would precipitate a lot more action. So I, yes, I agree. some people would be in desperation, but I think overall it would be a net benefit. So moving on to global human population, you've also written on this. You had a review paper come out in March of this year.

And in that you looked at the United Nations model projections that said that human population is expected to peak at 10 billion people sometime this number, a 25% increase from the current $8 billion. Based on your systems ecology work, how likely do you think that is? Well, even if you look at the, a lot of people have been working on this, if you look at the sort of demographic consensus, that really is right in sort of the best information that we have. And even if we went through, and I've done this is previous work,

even if we go through a massive war, And even if we have, you know, child mortality double over the, over the next century or so, even if there are three or four major pandemics that make COVID look like the common cold, it won't even affect the trajectory. And that's the thing. We have this massive demographic momentum. Why is that? Well, there's just so many of us.

And the fact that we're still increasing, our fertility rates. But are you, our, our, our, our, our, our, fertility rate peaked in 1965? It peaked in globally, yes. But if you look at many other nations, like for example, Nigeria, where it's tracking at five to seven children per female. And much of, yes, South American, Southern and sort of Latin America has reduced, South Asia has reduced a lot, but, but mainly that sort of Middle East sub-Saharan Africa area is still massively increasing. So globally, we're again, it changes by region, but globally we're locked into increases at least till the end of the century.

I would say that the best case scenario is that we hit some sort of peak. I disagree with that. I'll tell you why in a second, but go on. Okay. Well, I mean, all the models point to that. And regardless of what we do with fertility. Do the models include a proper accounting of the carbon pulse and how oil, especially and natural gas, underpin our actual food system? Do the models include many of the countries you mentioned? And here I'm arguing with an expert. I'm just throwing out some things. Yeah, no, no, I see what I'm saying.

Do the models include the fact that the wide boundary implications of climate, which you just said at three degrees Celsius is going to eliminate 50% of the species? What about countries like Nigeria and Saudi Arabia that have high growth rates under a three? I mean, how are they going to, how is that going to work? Okay. Well, I'll give you, I'll give you a good response. to that that I think we'll explain this simply. The number one predictive female fertility on the planet, and this is work where we've done, what do you think it is?

I'm talking a national scale. Lack of education? Nope. Income? No. Religion? Nope. Not even close. I would have thought that myself. The number one predictor is child mortality. So the higher the child mortality, the higher the number of kids? The fertility rate increases precipitately. It's not even linear. It's actually a threshold effect. So getting it around, I think it's about 0.03 child mortality, there's a huge spike in female fertility. And that's the insurance policy effect. If my child has a high- So that may not even be a social,

conscious thing. That's just a biological reaction. Exactly. So, as ironically, as our children die faster, and I'm doing a lot of work on child mortality and child health as it relates to both demography and climate change, and all the things are peaking. Yes, we've hit a plateau, but now they're starting to go up again. The ironic thing is that as you kill children, people's fertility is increase, and you see a regression back to that demographic change, that people change. through the development cycle. And this demographic transition will go backwards.

So we, if anything, we're going to see increasing rates of human population and growth closer to these extreme events. And that will eventually equilibrate because, you know, your caring capacity is lower and your overall mortality rates will be higher. But people will overcompensate for that just by fertility alone. So we're going to we're going to go to 10 billion easily, much poorer humans than the average today, I expect. You think too that, you know, from a demographic perspective, and I do a lot of work on, you know, reducing invasive species, and we try to kill populations like cats on islands.

And we just did a project on pigs on kangaroo island here in South Australia. And we try to maximize the way we can kill these populations to remove them from very ecologically sensitive areas. And if you get a demography like humans, the quickest way to do that is to target young reproductive females. In other words, those are the individuals that count. From a demographic perspective, males are irrelevant, and so are people beyond their reproductive years. So you don't have to kill basically if you have a massive mortality event, but you're still keeping the core of that young, fertile female. intact, that's what drives populations. All the other stuff is kind of demographically peripheral.

That's a very empirical way of saying that, you know, we have this system where females are driving the demography, and that's always been the case just based on our biology. So if that component is maintained, even over a short period, like if you manage to survive from, say, the ages of 14 to 25 or even 30, most of your reproductive, of lifespan is that is encompassed by that period. So if you die thereafter, not a problem from a demographic perspective. Your population will still grow. Your age structure will change, yes, but your overall trajectory won't.

So had we just started the interview now, I would have two hours of questions. Yeah, this opens up a huge area. Well, let's start here and then backtrack. If we had a reality roundtable, right now with you and Elon Musk, he's saying kind of the exact opposite that the human system needs more babies, otherwise we're going to implode. What is your response to that? That's exactly what a CEO would say in our economic system. The number of consumers increases his profit margins. And that's the only thing. There is, if you look at all the evidence for how

population affects average well-being of the individual. In every single case, more people equals a lower well-being. We have housing crisis. We have transport crises. We have political crises. We have refugees moving in that increases people's perception of their jobs being stolen, that their resources are being taken. So we have an uptake in extremist politics. We have we have school issues, you know, the number of schools being built. We have infrastructure problems. We have expansion of agriculture and then precipitating more extinctions. Every single element you look at in terms of human, higher human population densities, in terms of disease and children, in terms of the availability of food and the distribution of wealth, every single

one of them reduces average well-being. The only thing it increases is a problem. It's margin in a completely capitalist society. That's it. Well, it increases the market. The market needs babies to buy diapers, then toys, then teachers, then cars. When a CEO of a corporation tells you they need more people because it's good for society, it's good for them. And that's it.

Until we're at a three degrees world with half of the species, including pollinators, gone, there are no profits. No, that's exactly right. So it's a short-term response. But the best thing. we can do to increase the well-being of people on the planet today is to reduce our densities. If you look at all the highest well-being indices in almost every country in the world, the places with the highest well-being indices are those with the lowest population densities.

So you said reduce our densities. Is that meaningfully different than reduce our populations? All that means is that we should basically impart large-scale culturally appropriate, non-coercive family planning globally, and that we should open up our immigration policies to include people that can work to provide, for example, the labor shortages, it's an easy problem, that's an immigration problem, it's not a fertility problem. It's a choice countries make, you know, places like Japan, places like Italy that have declining populations.

In Japan's case in particular, that's mainly, because of their immigration policies. They don't allow people to come in to take up those, those labor shortages. We do it in Australia as well. And in Japan, Jeremy Grantham was on the show, and he said people aren't interested in having sex anymore as one. Well, look, in Australia, if you took out the immigration component,

we would be just at replacement right now. Replacement is like 2.1 babies per? Yeah, 2.1-ish, yeah. Yeah. But we're growing at 1% per annum. That's net immigration. 1% people per annum? Yes.

Yep. That's our population right now is growing at that right. And that's almost entirely immigration. I think the number I looked 10 years ago, if you take the, um, the, the deaths and if you take the births and subtract the deaths, 10 years ago, it was like 85 million net new human babies per year. I think it's down to 81 million. Yeah.

That's about right. Something like that. That's correct. Yeah. Yeah. So we, we've entered a new. phase. In fact, we entered that phase in the early 60s where, and this is work we have ongoing at the moment, that shows that we went from a, what we call a technical terms, and I'll try to explain

them well, from a depensation phase to a compensation phase. Now, let me explain what that means. Depensation in population dynamics means that when you add individuals to a population, the average fertility or the average rate of increase also increases. So this is the idea of a minimum number of people that society needs to function well, right? Beyond a certain point, the per capita competition starts to kick in. And therefore, every subsequent increment in population size actually decreases population growth. That's because there is no more facilitation component to adding more people. More people is a net detriment because actually fertility ends up declining. We've passed

that phase in 1962. And ever since then, the entire globe has been on this downward trajectory that more people added lower population growth rate, such that even if you extend that out to the to zero growth, i.e. stability, that still puts us in the range of about 10 billion people by 2080 end of the century. Does this rhyme or track with other species as well, I assume? This is pretty much the standard amongst all species. The only difference is that in humans, we've artificially inflated our carrying capacity through technological innovation over the course of our development.

Because of fossil fuels, I would say. Mainly because of fossil fuels. Yeah. If you also look at that transition from depensation to compensation, that pretty much was contemporaneous with this transition from using more than one Earth per year in terms of the global ecological footprint. So we transitioned to net users of resources as opposed to net replaces. So now we're operating at the sort of, I think, what's the average, about two Earths per year?

We're taking about double what we could possibly replace. And it's up to, you know, six times in the U.S. And that's just the daily and annual flows. That assumes away the ancient sunlight and minerals that we're adding. Yeah. Yeah. So let me, here's a very salient question in discussions today. For those people who are very aware and concerned about global heating and understand

the global economic juggernaut, what is the proportion of, impact of population growth on climate change in comparison to just the consumption of existing populations. How would you break out the impact on climate and emissions between those two? But about 80% of our total emissions contribution to heating is from increasing population, 20% from increasing consumption. So you add, because that's the other thing people don't tend to realize is that the average per capita consumption rate globally has doubled since 1970, pretty much. So not only have we increased by fourfold, almost, well, threefold since then, but the average per capita rate of consumption is doubled.

So not only are there many more people, but on average, we're using twice as many resources per person. So it's not the opposite. And so when you look at the contribution to warming, and we've done this relationship, about 80% is due simply to the number of people. Because it's growing in a much faster rate compared to per capita consumption rates. It's quite striking. That I can provide that paper to you at some point if your listeners are interesting. Yeah, we'll put it in the show notes. So I assume that if we are headed and you were pretty confident that,

barring a nuclear war, you know, including pandemics and wars and famines and stock market collapses or whatever else, that we are headed to 10 billion because of the momentum that you described. So what would be the environmental impact if we continue to have the same levels of resource consumption per capita with, you know, energy, water, agricultural impacts at 10 billion that we have at 8 billion? And obviously, I've answered my own question. I think you have. Yeah, it's not a rosy picture. Put it that way. We're getting into the realms of, you know, trying to predict proportions and percentages and things like that are quite difficult. But I guess to encapsular summarize this, there isn't a single metric that we can see today that's in the right direction.

In other words, all of these things are conspiring to go exactly the opposite that we want them to or that they should be going. And that means that all of these complex interactions will multiply and cause these unforeseen outcomes that we can't possibly predict, even with a very, you know, complex model. Because these are, these are, these are, basically, this is, you know, the butterfly effect in complex adaptive systems. We have these interacting elements that will interact in such complex ways that it's difficult to see how there will be anything but magnifying the predicted extent of the damage

that we will see by the end of the century or beyond. So I don't, like I said, it's hard for me to see any way out no matter what we do. It's almost to the point now that you accept, again, I come back to my sort of mantra, you accept that the future will be terrible, but you can perhaps make it a little bit less terrible for some people. And that doesn't mean you should hoard resources and exclude everyone, sort of like the extremist right-wing politic approach to things. But it does mean that solutions need to be of sufficient magnitude that they address certain things.

Like, for example, food wastage. You know, that seems like a very small thing. But, you know, if we manage to eradicate food, food wasteage, or at least reduce it substantially, we wouldn't need the agricultural expansion that our growing populations will demand quite to the same extent. So we'll have fewer extinctions that are a result. So that's a good thing. It doesn't mean people won't suffer. It just means that we'll have a slightly less catastrophic outcome. So what are the policies that could make a difference in this? And by the way, here's my view on population.

I think there, well, you just told me the facts. It's 80% due to population numbers and 20% due to consumption. Obviously, I think the wealthier nations should use less. And we probably shouldn't have as many people having babies worldwide. But I, of the three timelines that I talk about, pre-crisis, bend versus break and a more stable state in 20, 30, 50 years from now, I think population, the discussion of population isn't going to happen in the near term. And if it did, if we stopped having babies worldwide for whatever reason, that would precipitate the financial overhang and wars over resources, et cetera, because it's been a musical

chair, Ponzi scheme, the financial representations of biophysical reality. So I think climate change is, is hard enough to convey to people, the population story you've told is another order of magnitude harder. True, but if you take that perspective of, and I'll quote you, stopping having babies, that's not actually what one should advocate at all. I think a family planning so that you manage your family size

to a point that is acceptable to you as a human, as an individual, but also takes into consideration, The legacy effects. So if you recycle, if you don't do overseas trips, if you buy an electric car, if you hang your clothes out to dry instead of using the dryer, you eat vegetarian, blah, blah, blah, all the things one individual can do. The effect on your emissions are an order of magnitude lower than deciding to have one fewer children in your family.

So zero instead of one, one instead of two, two instead of three. Exactly. If we had a policy, for example, say two is great. More than two, maybe we want to think about that. It doesn't preclude people from fulfilling that evolutionary need to reproduce, which we all have. I mean, that dictates all of human behavior, basically. We're not saying people don't have babies. We're just saying, think about how you, how the kind of life you can give to your children. And part of this is reducing child mortality. You know, there's an ulterior motive there because it does reduce fertility. It's the strongest effect in reducing female fertility.

And having the ability to make those decisions at the family level for both men and women. That's essential. And it has to be done culturally appropriately. It has to be done in a non-coerative way. It has to be ethically acceptable. It's not, there's no one-size fits all. It kind of has to be done globally, doesn't it? It has to be done globally, but it's a sort of a tailor-made approach.

That's what family planning is about. per region, and it considers all of the other components, that religion in the society, the economic development level, all the cultural components, belief systems, various other things. And there are plenty of examples where it's worked very well without being an imposition. And, you know, middle-aged white blocs like myself living in rich countries aren't saying, you should stop reading because that's not what we're saying at all. We're saying that we need family planning.

So 2.1, maybe you could briefly explain why 2.1, children per female is the replacement rate globally. If you will get married and you have 2.1 children and everyone did that, that the population would stay the same. Is that correct? Yes. Well, that accounts for both the fact that you're going to have female and male children. Males don't reproduce per se. They don't produce babies. They produce sperm. So you can only have as many babies as there are a number of women, right? Until men start getting pregnant, that's not going to change. And then the small.

Point one, they accounts for the global mortality rates in children. Okay. And what is, it's 2.1 would be even. What is the number now, the fertility rate globally? Globally, it is, if I recall, about 2.8, 2.9, somewhere in that vicinity. Yeah. So it has been declining globally, but it's still high enough that we won't make that transition in most countries until quite later down to track. So how important is education, especially for women, and can education trump or overcome the financial market economic imperative?

that drives our society? Yes, well, this is a little bit problematic for several reasons because it's emancipation of women's rights and giving people the economic freedom to make decisions in their life and not be coerced and be in control of their own bodies and improving their own well-being, both economically and otherwise, through education, these are all grand things. You know, you make better informed decisions.

Generally speaking, your family members have better lives. There's less suffering and you have more freedom and you experience more of life. And so these are all great things. The flip side, of course, is that when you increase your economic standing, you increase your consumption rate. So that's partially imposed by the economic systems that we have. so that it's almost imposed that you increase your consumption as your education and therefore and your per capita wealth increases.

There's a great example of that in terms of refugees. When refugees come from low consumption countries on average and they move to high consumption countries, they adopt the same consumption rates of the high consumption country, their host country, within a few months. And this happens globally. So it's imposed by the system. You can't even choose not to be a consumer when you move to these countries. That's the system that's there.

And if you have more means, you end up spending more. It's designed to make you spend money and therefore consume. So it's a multi-level problem and it's a very, again, a complex set of systems. But it fundamentally comes down giving people the choice to make their own decisions. and that education is essential component of that. And that's incorporated into the best practice family planning programs that are available. And access to birth control widely and freely, I assume is a big part of it too. It's more than just access, because access alone will not shift fertility per se.

It has to be accompanied by actual education and family planning programs. And that's a huge cultural component to that as well. Okay, so here is an oft-stated assertion. I'd like your opinion on it. If people understand our ecological brink and understand the scientific thesis you've outlined here, and they realize that globally we should continue our evolutionary imperative of having children and doing the acts that cause having children. But 2.1 global average is the more sustainable outcome number. Those people around the world that are equal-lit and have a value system that care about

future generations and the biosphere will actually choose to do that, whereas the people who don't have a value system about dolphins, oceans, and a livable earth might have six kids. So how's, I hear that a lot. What are your responses to that framing? Yeah, well, I guess part of the educational component is just showing the net benefits of smaller families for those people and that the average well-being per individual in the family. It actually comes right down to that, that if people realize that, you know, a very crowded house has fewer diseases for children, for example, there's fewer hospital trips. There's less competition among siblings. There's usually a better part of resources available for the

extracurricular activities of the children in the family. And the list goes on and on and on. They have a better quality food. So. Except, except, let me ask you this. So you said earlier, there was a biological imperative that if there's low fertility rates, that results in more babies. What if we go from 50 to 100 years of economic growth to the backside of the carbon pulse, there will be an economic equivalent of low mortality. It's low economic vitality. Could that imply the impulse to have more children to support you as you get older and such? Well, if we also have simultaneously focused on reducing child mortality in those situations.

So while you might not have a lot, but if you focused on preventing, and most child mortality occurs in the first year of life, right? If we really put the emphasis on child health and the raising of children to that age, you would have less of an impetus to invoke that subconscious insurance policy in terms of fertility. So you can't, you'd have to do both. So we're in a mess. but what you're telling me is of all the things that we could do to improve the odds of avoiding a ghastly future, that reducing infant mortality is one of them. That's a big one. I'd say probably the next biggest thing is a complete restructure of the economic system in which we work.

And that's a big ask because it's tendrils have, penetrated every orifice of every component of society. So it's not something that it's a quick fix. I personally think the worst invention that humans ever came up with, it wasn't nuclear bombs and it wasn't, you know, chemical warfare. It was actually in corporatization. So the creation of companies and public, companies going public so that you outsource the ownership to people that aren't making the decisions, you divorce ethical decision making from, from profit maximization. And so I think the worst thing that ever occurred is the creation of a stock market.

That one brilliant idea provided the template for the destruction of the planet. And that to me was the when it really started because there's no way that you can incorporate good human decision making that's morally environmentally ethical when your decision makers have nothing to do with those decisions. All they want is the bottom line. I don't know how much you know of my work, Corey, but one of the lines in my movie and I say it often is we've outsourced our wisdom and decision making to the market. Exactly. So I think we're on the same page there. Another thing we could do is we could make all political donations illegal because there isn't a single democracy on this planet. It's all shades of a plutocracy. And as soon as you

can buy decision making for profit maximization, then again, you have the same effect. You do, you have decisions that are for the few and not for the many. And that includes a societal well-being. And so those three things alone, reducing child mortality, getting rid of public companies and making political donations illegal would make a huge dent in reducing how shitty are shitty future is going to be. What kind of changes have you made in your own life, in your personal life being aware of these things to be more aligned with the future you'd like to see, or do you think individual choices are not relevant in the scale and scope of what you're describing?

Individual choices are relevant, I think, but they have to be gauged relative to these, you know, the scale effects, obviously. So I think if I was, you know, traveling overseas every second day and I were, I had 16 children and I was, you know, embraced in all sorts of consumerism that I could possibly think of. If I managed to, say, for example, make political donations illegal, it would sort of dwarf all of those negative effects, right? So you want to be a net positive for the planet. Exactly. But at the same time, those personal choices are really important, not just for, you know, I'm a hypocrite like all humans. I'm alive, so I'm a hypocrite. You know, it's the, I like that old meme. It's very old now.

was, you know, the woman holding a sign at a rally. And it said, save the planet, kill yourself. That's a bit of an extreme. But fundamentally, she's right. So, you know, just being alive, you consume, right? So there are choices to, yes, as an academic, I fly overseas and that's, that's bad. I have a car. That's bad. Public transport isn't available. I live on a farm. One of the reasons I bought the farmers to produce more food, so I would rely less on, you know, importing food from elsewhere. I like my wine, so I make it myself. You know, I made choices.

I have one child. You had two choices of buying the farm. You bought the real farm instead of buying the farm. Yes, exactly. But, you know, I have one child. I try to limit my consumption. I eat locally. I, you know, there's small things I can do.

But, you know, from that as an individual, you know, I support the, the parties with policies. I think that's one of my biggest. influences is my vote. And in Australia, you, you are obliged to vote. We don't have a choice. So that's a good thing. Is there, you know, like climate change, probably even more than climate change, natalism and overpopulation is a very heated and contentious topic that doesn't make it

into the national stage because it's very threatening. talk about cognitive dissonance. Have you seen any change in that in your lifetime of studying these things? Well, I mean, the first population paper I ever wrote, I received death threats quite regularly from that. The biggest hate mail campaign I've ever received, as soon as you start talking about human reproductive rights, it gets very heated very quickly. And that's wrapped up into culture and religion and all sorts of things, politics. So that comes with it. What, you know, some of the bigger changes I've seen in my life, for development agencies in the United Nations,

which were very active in family planning right up until the 90s. And then a massive shift happened where the Catholic Church actually got involved. And it became basically anathema to even mention the word family planning thereafter. And that still has an effect. And even today, when we deal with development agencies in the United Nations, one of my colleagues was just at one of the United Nations meetings. And they're, they're actually,

the United Nations precludes their employees from even mentioning it. So it's a policy that is starting to break down because there's a lot of people in so-called lower income countries that are, you know, well-educated and are seeing the benefits or at least seeing the detriments of, of high populations in their countries. They're starting to say, look,

dark people in low-income countries in in the south how to do business because we actually can benefit from this so we're working with a lot of local people now that's starting to come out in the conversation but it's a very it's still very heated even in the development circles and these are very educated and and ethically and morally upstanding people that really want to better the world but even their politics are so tight around this to subject that it's almost impossible to get them to speak about it publicly, let alone privately. So we still have a lot of work there, definitely. What's your best speculation at a sustainable human population over the long term? That's a very interesting question. There's been a lot of work done on that over the years.

From today, from an ecological footprint perspective, from a demographic momentum, from a well-being perspective and from an over-consumption perspective, all things are kind of pointing into that 2 to 3 billion range, perhaps slightly more, perhaps slightly less, which was approximately what we were back in the 50s, just before the, well, just as the baby boom was taking off. So if we managed to get us globally, and again, that's highly geographically variable

because some places have higher productivity than others. But on average, globally, if we've sort of stuck to that kind of number, that would be a good target. It would certainly provide adequate consumers for markets to be more or less free, with some limitations, of course. It would give people a very good lifestyle and benefit and well-being. Our health would be better. Our long-term food production would be more sustainable. we would be able to reel in a lot of that climate change momentum and perhaps even fix it. We'd even be able to restore a lot of ecosystems.

But will we come to that by design or by disaster? I tend to think the latter rather than a planned sort of target. That's my base case too, that we continue to grow population for another 30 years or so. And then there's a gigafammon in the back half of the century. But Rex Weiler has been on the program. He was one of the co-founders of Greenpeace and he did the math with me. And like we said, we're growing 80 million net new humans per year. So that's 800 million per decade.

But if we did what you said earlier, a campaign on education, especially of women, family planning, education, access to free contraceptives that you could reverse. that and go to a negative 1.1% per year, which actually works out to around 800 million per year with no draconian early deaths or famine or wars or anything. So in, you know, 30, 40, 50 years, if that were true, we could be at 2 billion in theory. Yeah, I think actually if I looked at some of the reduction, it would put us probably more like the middle of next century that would be viable to reach some of those numbers. But yeah, we're talking about the same. I mean, the next century is like a fantasy sci-fi novel. I mean,

I don't even know what 2030 is going to be. Exactly. Yeah, yeah, yeah. But, but yes, the timeframes are sort of in the 100-year range that we could possibly do that. Yeah. Okay. If it were designed, I feel more like you, though, that a lot of that will be imposed. Yeah. And not in a nice way. Well, you're not the first to suggest that on this show. I don't think. No, definitely not. This has been eye-opening and enjoyable. We've never spoken before and you're a good bloke. Let me ask you a few closing questions and thank you for your time this Adelaide morning.

Do you have any personal advice to listeners, either those who are very familiar with what you've said or those that you just dropped a bomb on their life with the last hour and a half. What are you advise people who are becoming aware of our reality? I think I could say to most people that indifference is probably the worst path to choose. So you can avoid uncomfortable conversations and topics. But ultimately, even though it's uncomfortable, ultimately you can improve your own well-being and that are your families. If you put a little bit of emphasis on what these biggest scale decisions mean for you.

And, you know, in most people that, I don't care if you were brought up in the inner city or you, you know, hard right-winger or, you know, lefty-greeny, you put someone out in the bush somewhere in a nice day. they feel good, you know. And you just, you don't even have to see a lot of animals. You know, a butterfly might flip by it. It's, it's a good feeling. We evolved in these kind of systems and we feel comfortable there.

Just the fact that you have some green space and get away from people and you want to maintain some element of that into the future and your children can benefit from that. It's worth making a bit of noise about how we can change these systems for the better. So I think ultimately it sounds selfish, but I think the humans we think in a selfish or at least a very nuclear way, the people around us and our own lives. And if once we realize that we can make our lives better by consuming less and being more involved with the decision making that affects our societies, then I think we have a chance of a future that's not awful or ghastly as we live. like to say. Well, you wrote, you wrote some papers with the title, Gassley, and then we'll put them in the show notes. What about young people, how would you change that advice for someone in their early 20s? Well, I have a 17-year-old daughter who is in fact right at that age. And being my daughter,

of course, she's been aware of this since she was five years old. I remember making her cry when she was about six, just telling her about climate change alone and feeling, feeling very bad about it afterwards, but she's made many decisions already. And, you know, 17, you make a lot of decisions that don't necessarily manifest later on. But most of her generation, they shun mass consumerism that I've seen anyway. They do not want families. They don't want to drive. Even in Australia, they don't, they don't want to drink or take drugs, which is, blows my mind. I know, it's, it's, it's, it's, it's, it's, it's, it's why would that be? You would think that that would be an escape just on a cultural demographic observation. Yeah, it's a very interesting topic. I'm not sure that I have any of the answers, but they seem to be in a little bit of a shell shock about the future and they're really focused on being good people, uh, I think. And, and I think I do have a lot of hope with the younger generations seeing that is that they're not, you know, chomping at the bit to make them, money or to see the most places or have the biggest family. Just that ownership, that consumerism,

I don't see the same that when I grew up. I could be wrong. There's the seed of a cultural change there. I see it too. Yeah. And that's encouraging. And I think while they're generally, they're very sensitive. You know, at the university, the students coming in now, you have to walk on eggshells because the slightest thing will put them off. You know, COVID really knocked them for six, as we say in Australia. They're very susceptible and their resilience is very low. And you can understand why. And they've generally very freaked out about the future. But they're also thinking about it, not in a form of desperation. They're actually changing how they live. So are you teaching right now? I am, yes. What is the name of the class you teach or more than one? Well, I teach into

quite a few, but I do everything from biodiversity, conservation, to restoration, ecology, to teaching statistics and mathematics and modeling, to talking about, you know, global, food systems and things like that. So touches on all elements of environment. So the topics that we discussed on this podcast, you tell your students? Yeah, I'm actually a little bit infamous for freaking out people in the second and 30 years. So they say, oh, we would wait till Corey's classes because he'll give you a bit of pill.

So do people choose to take your class or do they have to? Well, depending on which stream they're in, yes, they often have to take it. But it is quite interesting to see that most of them are quite up to speed with the fact that things are bad. They don't quite get the gravity or the magnitude of how bad it is. And I think that's what really kind of shocks them. But almost always, there's someone at the end of one of these classes that says, what are you doing to tell more people about this? That's the question that comes out the most.

And I'm thinking, well, I'm doing a lot, but clearly I could do more. You know, if it takes second year university students to get this message, I'm clearly not getting the message out as much as I should. I agree with you. So let me ask you this, and I know we're running a little over here. It was my experience when I taught Reality 101 for nine years at the University of Minnesota that they signed up for it because it was kind of cool because we were talking about climate change and energy and the environment. And then during the class, they were totally shell-shocked because I told them things that they had never thought about, like plastics and peak oil and money's relationship to net energy. But at the end of the semester, they're like, I learned more depressing things about our reality than I had imagined. But I actually feel better about it because I have a context for understanding how things fit together.

And it sucks. But I feel better for understanding it. Do your students feel something similar, do you think? I get some feedback occasionally that the kind of information that we give them is often very useful for their immediate families and friends and connections. And that when people go, oh, you know, don't worry about that stuff. It's not a big deal. And they can, well, actually, X, Y, Z and ABC, and this is happening. This is something.

They feel empowered that they can actually start illicit change within their own peer groups and their own families. And I think that's where it has to start because we are social beings. We operate in small nuclear networks. We don't have influence at the political level, most of us. And so if we can affect some small change within even the perspective of our immediate neighbors and our families, that's an empowering feeling. And so I think that's what I hear from students often is that they can do that now. A few more questions. What do you care most about in the world, Corey Bradshaw, other than velvet worms?

What I care about most in the world? I think just to look outside and see the beauty of natural systems, that makes me the happiest. You know, when I see, when I see destruction, when I see, you know, it just affects my soul. I can't describe it any other way. And so just maintaining some sort of naturalist, naturalness. When you look outside and see the beauty of the forest and the ocean and the cucoburras and the platypus or whatever you see, do you simultaneously see a future echo of it and the emotions of discounting that back because of your research and awareness of the future of global ecosystems? When I went to South Africa for the first time and I went to the Kruger National Park.

park. I took a photo of a white rhino running away in the dusk. And the way it worked out is that it was kind of fuzzy and a little, because it was low light. It almost looked like the rhino as a ghost or becoming one. And I used that as an analogy often in my talks about the ghost rhino that's disappearing. I got to see that rhino that day. Will I be able to see it in 20, 30 years? Maybe not. And so, but I took great pleasure in the fact that I could see that animal. And it might be gone, but I took pleasure in the moment. And I can do stuff to hopefully maximize its resilience and potential for persistence in the future.

But I saw it then. And so I took pleasure in that then. I take a lot of photos. That's, you know, it's not very fulfilling from that perspective. I like seeing things in the flesh. But at least I can look at the photos and say, you know, that's a beautiful thing. I saw that. I took that photo.

I was there. I took some pleasure from that. that keeps me kind of going, you know. If you could wave a magic wand and there was no personal recourse to you, what is one thing you would do to improve human and planetary futures? If I could do one thing, I would make all political donations illegal. That, to me, would be the biggest impact I could possibly make on the planet. If I could snap my fingers, we had democracies, actual democracies.

be more than I could ever hope to achieve in my lifetime as a scientist. Well, here, here. So this has been great. I would like to have you back because I think we just scratched the surface. If you do come back, what is one topic that is relevant to human futures that we didn't discuss today that you are a passionate about or a nerd about that you would be willing to take a deep dive on? Well, I think that there's a lot of more deep diving to do just on the population, child health, climate change interactions. And we're just starting to explore those in more detail.

And I think that we could get into a lot of arguments about certainly net benefits and detriments in terms of population density and the evidence underlying those. We can go in a lot more detail there, I think. But if there's an appetite for that, perhaps, yeah. It's part of our future and it's quite relevant. So we'll try to do a population roundtable and I will invite you back. Well, I would certainly, if that, if that incurs, definitely getting some better representation to both in terms of gender, origin, race. Absolutely. I think that's a really good idea and you get different perspectives, but you all.

also see that it's a bigger problem and it's, yeah, I, you know, I can't help the way I look who I am. Yeah, yeah. It's, it's, I'm very cognizant of the fact that I'm, I'm, I'm a middle-aged white man from a rich country. And regardless of the evidence, you need to open that conversation up to a broader group. Um, I'll set it up, Corey. Okay.

Um, brilliant. And I can even potentially suggest names to, Nate, um, if you're interested. Thank you so much. I hope you enjoy your, uh, Adelaide. weekend and continue my friend. Thank you, Nate. Lovely to meet you and I appreciate the chance to talk. If you enjoyed or learned from this episode of The Great Simplification, please follow us on your favorite podcast platform. You can also visit thegreat simplification.com for references and show notes from today's conversation. And to connect with fellow listeners of this podcast, check out our Discord channel. This show

Hosted by me, Nate Hagan's, edited by No Troublemakers Media, and produced by Misty Stinnett, Leslie Batlutz, Brady Hyan, and Lizzie Siriani.