Peter Brannen is an award-winning science journalist with expertise in ocean science, deep time, astrobiology, and the carbon cycle. Peter walks Ross and Christophe through the five major mass extinctions in Earth’s history, discussing what events triggered each extinction and how plant and animal life changed each time.
Full Transcript
Ross Kenyon: It’s all in the name.
Alexsandra Guerra: [music] You’re listening to the Reversing Climate Change podcast by the team at Nori, the carbon removal marketplace. This is a show about the innovators and entrepreneurs developing solutions to climate change.
Christophe Jospe: Hello and welcome to the Reversing Climate Change podcast. My name is Christophe Jospe. I’m sitting here with my co-host and colleague Ross Kenyon in the Boulder Library. I think that’s Boulder, Colorado or Colorado or Colorado. It’s definitely not Colorado. Based on what part of the country you’re from. I don’t know. It’s kind of cool. We’re actually here. For the next three months, not Boulder, but Colorado itself, going through a program. If you are subscribed to our newsletter, you would have heard that we’re in the Techstars Sustainability Accelerator with the Nature Conservancy, which is kind of cool.
It’s kind of like startup school for people trying to make an impact in the world.
Ross Kenyon: Yeah, it’s been great so far. We’ve been here for a week and then we had to make a little trip to Boulder, a couple of podcasts we wanted to do.
Christophe Jospe: Trip down memory lane, Ross actually spent some time, he was one of those people who was busking on Pearl Street and organizing shows, doing like, he told me, so now I’m going to tell you, listener. It’s all going to be cut. That’s okay. Okay. Well, yeah, he had a raw garlic press. I don’t know if there are people in Boulder who still do that. I think Ross set the trend years ago.
Ross Kenyon: I got to stop telling you things. Okay. Well, I read a book and then made my colleagues read it. And that’s why we’re here. Today we have with us Peter Brannen, who is the author of The Ends of the World, Volcanic Apocalypses, Lethal Oceans in Our Quest to Understand Earth’s Past Mass Extinctions. Peter writes regularly for the Atlantic. Peter, we’re very happy to have you here.
Peter Brannen: Thanks for having me.
Ross Kenyon: I love stuff like this. I love geology books that are written for a popular audience because otherwise it’s stultifying and difficult and deep time, man. We’re in Boulder, so we can be a little hippie with it. How do you even start to think about it? Because I don’t know. I’m back here in Boulder. I haven’t been here in a while and it seems like that was long ago, but even like thousands of years, once you get beyond that, I got nothing.
Peter Brannen: Right, yeah. And I think, at least in sort of popular science, space gets a lot of press for being mind-blowing, and geology and deep time don’t get nearly enough because it’s just as mind-blowing when you think about... I mean, so for instance, this building stone that surrounds us is a lion sandstone from the Permian, which was 200... This stuff is probably, I don’t know, 260 million years old or something like that, which sounds like a long time ago, but that’s a half billion years old. And the planet is... Four and a half billion years old.
Geologists have all sorts of tricks for thinking about how vast Earth history is. The one I use in the book and one of my favorites is if you imagine that every footstep you take is a century and you go for a walk. You take one footstep and there’s a third of the world’s coral reefs appear and most of the dark side of the planet is still pretty dark at night and the Ottoman Empire still exists. It’s kind of a different world and you’ve only taken one footstep. And you take, you know, 20 more footsteps and you’re at the zero AD or BC and the Roman Empire exists and you haven’t really gone very far.
And then you ask people, you know, how much further of a walk do you have to go to the beginning of Earth history? And they think, all right, you go, you take a little walk and, you know, there’ll be a little bully mammoths a little further after that. They’re dinosaurs. And then... You know, it might be sort of a trudge, but by the end of the day, at least, of course, you’d be at the beginning of Earth history. But the actual truth is that you’d have to walk for 20 miles a day for almost four years to get to the beginning of Earth history.
So those are the sort of skills we’re talking about. And they are, you know, not relatable in a human lifetime and sort of the lifespan of a human. But what’s crazy about what we’re doing to the planet today is that it actually it’s significant. In ways that only a few moments in Earth history in that entire time span have been. So we really do have a pretty dramatic influence on the environment.
Ross Kenyon: Indeed. And you primed it very well because you go through to start the first five mass extinctions and these all sound terrible. Your book is apocalyptic in a fun way. If you like survival books, maybe you’ll like this too.
Christophe Jospe: Yeah, I thought it was, before reading it, I was like, where are the ends of the world and how do I get there? Is this going to show me how? Like, it felt like a Viking. He’s the house pet ant. Kind of.
Peter Brannen: I mean, in some ways it is sort of a travel log book. And sort of the secret language of geology, like once you start to understand how to read the rocks, you realize that these incredible events and moments in Earth history are just on the sides of highways. When you go to geology conferences, people will give talks and they’ll... Be talking about one of the most important things that’s ever happened. It’s like, oh, here I am on I-25 at this road cut studying this event. And most people just drive by and have no idea.
So it actually becomes very dangerous to drive once you start learning about geology.
Ross Kenyon: This might be a very, very silly question, but I’ve never understood when people say this rock or this event is such a years old. Does that just mean that was the last time this rock was transformed? Because clearly all the matter on Earth has mostly been here since the very beginning. Yeah. So is that what it means? It was the last time it changed in a meaningful way?
Peter Brannen: Yeah. So for sedimentary rocks, it was when they were deposited. So like beach sand, where I’m from in New England, a lot of the beach sand is eroded from granite that is 500 million years old. But if that was deposited in the record as sort of a sandstone, which it might be in the future, this beach sand, if you dated it, yeah, you’d get the wrong date for when that... You’d be off by 500 million years.
Christophe Jospe: Could you define what that means for a rock to become deposited?
Peter Brannen: So... Things erode on the Earth’s surface and they’re carried by rivers and get sort of laid down in river channels or they make it all the way to the sea and it gets laid down as ocean sediment and it just slowly stacks up over millions of years. In the deep sea, it’s something like a centimeter per millennium is the rate at which if you find like silt stones or shales, that’s about how fast that rock was accumulating. And what that means is like if you find a giant wall of it, that took a really long time to build up.
You can see millions of years in one sort of outcrop depending on the kind of rock.
Ross Kenyon: Okay, so... Also, yeah, we’re getting a little off track. Oh, all the questions we’ve always wanted to ask. Can you take us through a tour of all five of them and then let’s talk about the Anthropocene and where we’re headed and what all that looks like?
Peter Brannen: Sure. I’ll do my best. It’s a lot of ground to cover.
Ross Kenyon: I know, I know. It’s just a half billion years. Ordovician is the first one, is that how you say it?
Peter Brannen: Yeah, yeah. So the Ordovician period, it’s after the Cambrian. So people have heard of the Cambrian Explosion. I mean, some people have... Where you sort of have this explosion in quotes of animal life into the fossil record where before there was single-celled life for all of Earth history. And then there’s a little weird stuff right before the Cambrian, but we don’t have to worry about that. But the Cambrian is really when you get these things that look like trilobites and things that look like horseshoe crabs. And the first fish ancestors, I mean, we’re fish descendants, so our ancestors are represented in the Cambrian as well.
Ross Kenyon: Is this where the eukaryotes come from? Is this the...
Peter Brannen: The earliest eukaryotes are way before this. But first, multicellular animals show up near the beginning of the Cambrian. But you find all this weird life in the Cambrian. But the Cambrian is actually not that happy of a time. There’s a lot of anoxic oceans. And so animal life starts, but it doesn’t really get off the ground until the Ordovician, which is the next period. It goes until 445 million years ago. And this is a world of... Reefs take off and there are these giant cephalopod nautiloids, these like squid-like things and these 20-foot long like ice cream cone shells.
Ross Kenyon: It’s Cthulhu.
Peter Brannen: Cthulhu, yeah, exactly.
Ross Kenyon: Cthulhu’s roaming the world at this point.
Peter Brannen: Yeah, yeah. Like fish are still very unimportant ecologically. It’s really a world dominated by things without backbones. It’s like a bug world. And it’s totally, there’s no life on land yet. Dinosaurs are hundreds of millions of years in the future. I went to Cincinnati, Ohio for this book to see what life was like in the Ordovician because Cincinnati was south of the equator.
Ross Kenyon: That’s a whole thing too, like trying to wrap your head around where stuff was on the planet, what that even means because it’s all relative to everything else.
Peter Brannen: This far back in time, it’s almost meaningless because Pangea hasn’t even come together yet. And that’s what most people’s sort of touchstone is for... Old, like, continent positions. Grade school kids. Yeah, right. Like, New England is still rifting off of the South Pole and isn’t going to crash into America in 100 million years. Like, it’s a very different planet. California doesn’t, or the whole West Coast doesn’t exist and won’t for a very long time. This is, where is it? It’s under, it’s at the bottom of the deep sea, basically.
Ross Kenyon: It’s, like, got subducted and pushed up or?
Peter Brannen: It just, it wasn’t, yeah, it wasn’t getting uplifted and pushed up yet.
Ross Kenyon: Okay, it hurts my head.
Peter Brannen: It does, yeah. So this is a totally different planet and there’s no life on land yet, but there’s tonnes of this crazy animal life under the water. And it’s the biggest over something like, I don’t know, 20 million years or something, biodiversity on the planet triples and it’s this big explosion of life. And then right at the end, it’s one of the biggest mass, like right at the very end, something like 85% of life on Earth goes extinct and geologically a very fast period of time. What happens at the exact same time is that there’s this devastating ice age, which we know because there’s rocks in the Sahara Desert, which at the time was over the South Pole, that look exactly like the sort of glacial rocks you find in like New England or Wisconsin.
And sea level drops hundreds of feet, which for things that are living... I didn’t explain that a lot of this ocean life lives in these shallow seas that are on top of the continents because sea level is incredibly high. And the deep oceans might not be very well oxygenated, so a lot of that life might be up on the continents. And so if you drop sea level by hundreds of feet, you destroy all that habitat, dropping the sea level by having this big ice age. And it also changes the circulation of the ocean, which might change where food is.
And so you get this big devastating mass extinction caused by an ice age, which is thought to be caused by a drop in CO2. So today we’re worried about CO2 going up too fast and it getting really warm. But in the Ordovician, it might have been the case that you sort of have this slow decline of CO2 and then you cross this threshold where you go into this devastating ice age. Drop in CO2 might be related to some sort of arcane geochemical things that might take too long to explain, but have to do with mountain building and that the Earth’s sort of in the long term, the Earth’s best way of getting rid of carbon dioxide is through this process called rock weathering where sort of it’s what it sounds like.
Rocks get worn down and the CO2 in the air eventually reacts in rainwater with rocks on land and gets deposited in the ocean as limestone after going through rivers and things like that.
Ross Kenyon: You did it.
Peter Brannen: Yeah, I guess I did it.
Ross Kenyon: Yeah, we’ve done episodes on mineralization of carbon dioxide and how that works too. We’ll put it in the show notes too if you aren’t as familiar.
Peter Brannen: Yeah, and it just so happens at this time that there’s one of the earliest phases of Appalachian mountain building is happening in the tropics. And today the Appalachians are sort of these unimpressive little mounds on the East Coast, but it’s thought that they might have been as tall as the Himalayas and they stretched from... I don’t know, Alabama to Greenland and just gigantic. And if you thrust something up in the middle of the tropics that’s exposed to more warmth and storms and things like that, that’s a really good way of taking CO2 out of the air.
Christophe Jospe: Really glad you brought up this example because I think it brings up the theme that, you know, the Earth has this carbon cycle that happens at different rates. You have fast and slow rates and men, geologists and geology moves slow, but keep us moving. So we made it through the ordination extinction.
Peter Brannen: And now I’m realizing that one’s actually very relevant to what you guys do.
Ross Kenyon: We’re going to make that carbon removal connection.
Peter Brannen: Yeah. The next one is the second mass extinction, which is 375 million years ago. And it is also a strange one. And it’s probably the most mysterious one. It’s the late Devonian mass extinction. So by this time, after the Ordovician mass extinction, fish radiate and sort of take over the ocean. And by the Devonian, it’s known as the age of fishes. You have all these weird alien fishes, most of it, which would look totally bizarre to us. Most dominant ones are these things called placoderms, which are covered in these thick, bony armor that are really terrifying.
There’s this one called duncalosteus, which... It’s most famously found in Cleveland. You go to the Vienna Natural History Museum, and they’ll have this amazing dunclosteus, and you’ll see where it’s from. It’s from Cleveland. And the riverbanks in Cleveland just spill out this stuff. They have these guillotine-like mouths. They have one of the biggest, strongest bite forces in Earth history, and they’re the sizes of buses. So I think they’re very underrated in terms of scary animals in Earth history. The placarderm. Watch out. Yeah. But they actually die at the end of the Devonian.
They barely make it through the biggest mass extinction. The Devonian’s weird also because there’s multiple mass extinctions, and there’s one especially big one where 99. 99% of the world’s largest reef system disappears. And this is also the same time that life first emerges onto land. Land plants first evolved around 385, 390 million years ago. So plants coming onto the continents welcome on all this animal life. Sort of insecty things in the oceans come onto land and become insects. And fish sort of follow them because now there’s food on land and they become everything.
All the wildlife you see on the land today with the backbone comes from these fish that waddled onto the land in the Devonian. But trees also have been implicated as maybe the mechanism of this mass extinction because, you know, we think of trees as these wonderful sort of life-giving things, which they are, but their first emergence onto the continents, they sort of engaged in this global geoengineering project. They dig roots into the ground and they created the first soils basically and liberated all these nutrients that had been stuck in continental rocks.
They dug the roots down in the ground and made all these soils and that washed in the river and released all sorts of things like phosphorus into the rivers and into the ocean, which today we go to Morocco and dig up phosphorus deposits and spread them on our crops and trees were basically doing the same thing. And we’re doing the same thing today. We’re in the Gulf of Mexico. You have... From agriculture in the Midwest where we’ve spread too much phosphorus, it washes into the Mississippi and then out into the Gulf of Mexico and you get these big dead zones.
So in the Devonian that might have been happening just on a global scale because trees are just taking over the planet and just sort of mucking things up.
Ross Kenyon: I love that trees are the villain of the Devonian. Great twist.
Peter Brannen: Yeah. And the Devonian actually ends in this devastating ice age that might be because trees are sucking so much CO2 out of the air. There’s also maybe a big volcano that happens thrown into the mix that might be contributing to it too. But it seems like the late Devonian is a stressful time in Earth history where the planet’s trying to adjust to this new actor on the planet. So I think in some ways it’s a really good analogy for what we are. Today, where our appearance on this planet has been very devastating, but I’m hoping we can sort of find some sort of equilibrium like trees eventually did and have some enduring geological legacy.
Christophe Jospe: You could argue that trees didn’t know better.
Peter Brannen: Exactly. Yeah. And we do. Ostensibly. Yeah. Right. So that was a really big one as well. But then you jump 250 to 252 million years ago. So this is a little over a hundred million years later and you get the biggest mass extinction of all time. And there’s no like close second place either. It almost sterilized the whole planet. It’s this thing called the end Permian mass extinction. And by the end Permian, you do have things walking around on land, you have trees and things like that. You have big reptiles and you have big things that are related to mammals that are dominating the planet, which is kind of weird because people think like mammals didn’t take over until the dinosaurs got wiped out.
And that’s true, but our side of the family tree actually did have a chance or sort of held the throne for a long time before this worst mass extinction ever and allowed sort of the age of reptiles to happen afterwards. And in the ocean, you have big reefs and things. One of the best examples of which is in Texas. I went to this place called the Guadalupe Mountains, which if you know what you’re looking at, you can see that you’re just hiking up a coral reef from 260 million years ago.
The reefs were totally destroyed after this. And the scariest thing about this mass extinction, which wiped out something like 96% of life on Earth, at least in the oceans, maybe a little less on land, but still incredibly devastating, and actually takes 10 million years to recover from, is that, you know, after 1980, when people discovered that the dinosaurs seemed to, their extinction had something to do with an asteroid hitting the planet, that they went back to older mass extinctions to see if asteroids could explain the rest of them, and they couldn’t find evidence for, you know, An iridium layer, like a layer of asteroid dust or a big crater or anything like that.
And they expected to find that for the Permian. But instead, what they found is this gigantic volcanic province in Russia called the Siberian Traps basically did its devastation by injecting an incredible amount of CO2 into the air. And this event is actually a runaway, really runaway global warming, ocean acidification, ocean anoxia, mass extinction. So again, pulling the same levers that we’re doing today.
Christophe Jospe: You know, the term that climate scientists sometimes use is feedback loops, right? So you have something that’s causing other things and then it just triggers another event which is going to emit even more CO2. Right.
Peter Brannen: Yeah. So it might be true that the initial warming kicked off something like methane in the deep sea or something like that. But just alone, the eruptions were so extreme that it can explain a lot of it. So... Enough lava erupted out of the Siberian Traps, it could cover the lower 48 United States a kilometer deep. This is over thousands of years, but it’s still...
Ross Kenyon: Yeah. In the book, you mentioned the square million miles or whatever it is. I’m just like a 5 million square miles. I don’t even know what that looks like, but it’s that big.
Peter Brannen: Well, you can go on Google Earth and if you go to Siberia and you see sort of like the brownish stuff, that’s all Siberian traps basalt. And it’s so remote that most people haven’t been there. But if you look at what the landscape looks like, it’s incredible. There’s just these giant plateaus of basalt and But that only covered part of the planet, so it can’t explain why everything on the planet died. Even on the South Pole, on the other side of the planet, everything is going extinct. In the deep sea, everything’s going extinct.
So it’s the gases that came out of the volcanoes. They had the misfortune of coming up through one of the world’s largest coal basins. It seems like the mass extinction kicks in as soon as the magma starts seeping sideways into the rock and intruding into these huge deposits of fossil fuels. And then you see these weird explosive pipe structures that come up from that. And so at the surface, they’re burning through all this gas and coal. And then at the surface, you have this hot CO2 and methane comes rocketing out of the earth in these giant explosions and Cinematic.
Ross Kenyon: What’s the PPM like? Do you know the parts per million?
Peter Brannen: Oh my God.
Ross Kenyon: Thousands? Yeah. Is it 10,000?
Peter Brannen: I’ve seen numbers like 8,000 parts per million or something like that. Going from like maybe, I don’t know, 600 or something. Not that different from what we’re doing today. And one person said, I talked to in the book is like, we don’t know if it got to like 30,000 parts of a million. And I was like, I started laughing because that sounds so insane. But he’s like, you have to remember, you’re killing everything on the planet without the help of like overfishing or habitat frag, like nothing we’re doing today. It has to be all chemistry and like all warming.
So you really, things have to really be going bad too. Almost kill everything on the planet. And there’s all these other mechanisms that have been invoked, like you lose oxygen in the ocean, and so you start getting this anoxic bacteria that’s making hydrogen sulfide, which is just incredibly poisonous for any animal life. And this guy I talked to in the book, Lee Kump, said he had people at NCAR actually down the street, the National Center for Atmospheric Research, run some... Permian like level oceans on their climate simulations where seawater was like 108 degrees or something like that.
And that the model started spitting out these things called hypercanes, which are hurricanes with 500 mile an hour winds that would be sucking this hydrogen sulfide out of the ocean and bringing it onto land, just poison gassing everything. So everything seemed to have been going wrong at this point.
Ross Kenyon: How does the world even recover after something like that? What’s left? What comes out of it?
Peter Brannen: Well, this is what’s sort of reassuring about geology is that in the long run, the planet’s going to be fine because it’s seen worse than us. But it does take 10 million years for the planet to recover after this. The early Triassic is the most miserable time in the entire history of animal life. Coral reefs are replaced by just piles of bacterial slime. Of the sort that you only see in the Precambrian before animal life. And it’s referred to as anachronistic in science papers, just because you’re back in these Precambrian oceans because there’s nothing alive, basically, which is kind of eerie.
And it does take a long time for life to recover. And the world that recovers is totally different. It’s weird to call it modern because you go into the age of dinosaurs, but you lose paleozoic life. So life has this certain character for hundreds of millions of years since the start of animal life, and it just looks totally different after that and does ever since. And mammals and reptiles have sort of switched positions.
Ross Kenyon: So have we been to the Mesozoic then after the Permian?
Peter Brannen: Yeah, that’s the beginning of the Mesozoic. Yeah. And so then I’m probably going a little too slow, but the next mass extinction is 50 million years later. And it’s basically the Permian junior, like another giant volcanic province erupts and all the same things are set in motion. This one is in the palette, like, um, This is when Pangaea is fully together and it’s actually starting to break up. And as it breaks up, you get another one of these big volcanic events that leaves behind this huge volcanic province that today you can find in the Palisades in New York City or right across from New York City.
You can see these giant cliffs of ancient magma right across from Manhattan. And you find the same rocks in Nova Scotia, Brazil, Spain, France, Morocco. They’re all over the world. And all the exact same things happen. And coral reefs, which have recovered by the very end of the Triassic, disappear for hundreds of thousands of years. And dinosaurs’ competitors, which are all these weird crocodile relatives, get wiped out so dinosaurs can suddenly take over. And then you set in motion 135 million years of the reign of dinosaurs. And then, of course, everyone knows about their mass extinction when the biggest rock that we know of to hit the planet in a billion years hits.
But what’s crazy about that one is another one of these big volcanic events is happening at the exact same time that the asteroid hits. And for the past 30 years, it’s been a very contentious issue of which has been more important. I would say that the smart money is still on the asteroid, but the closer people date the sort of Most eruptive phases of the volcano, it seems like it’s happening really close to the extinction. So people are still trying to tease out the relative effects of those two things. And that brings us today to today and the question of whether we’re in mass extinction now, which we can get into, but yeah.
Christophe Jospe: I’m going to push the brakes on you a little bit. I want to talk about the asteroid because it’s interesting thinking about mass extinctions that aren’t instantaneous, but the asteroid is a very instantaneous event, right? Like boom, dinosaurs die. I mean, we’ve all seen, you know, the beginning of time or whatever. So can you talk a little bit about the unique extinction there?
Peter Brannen: Yeah. In some ways, I think it’s a little unfortunate that this freak rock is responsible for the most famous mass extinction because other ones sort of have these like really important lessons to teach us. And that’s the only one anyone knows. But yeah, like how do we know about it or just how it caused?
Christophe Jospe: I guess just comparing up to the extinctions you’ve talked about in terms of Yeah, yeah, yeah. And the instantaneous nature of the extensions. Right.
Peter Brannen: So, yeah, there’s some people that would argue that the dinosaur extinction took 15 minutes, which is just a really bad afternoon, basically, that this asteroid hit Mexico. It ejected so much rock around the world that when it re-entered the atmosphere, it made it as hot as a pizza oven, basically, for 20 minutes. And then the planet’s covered in so much dust that photosynthesis shuts down. I think there’s a lot of people who are becoming more skeptical of that account of the asteroid. For one thing, because it seems like if you made the planet as hot as a pizza oven for any length of time, you wouldn’t have much life on land ever again.
So it just seems almost a little too extreme. But maybe it’s possible. You do see a lot of things that burrowed survive. So maybe that’s how they made it through. But yeah, some of the other mass extinctions... Geologists will talk about as basically instantaneous. And what they mean by that is that it took less than 50,000 years, which for us sounds like a really long time. But geologically, that is as fast as things can happen, basically. And people still argue about that. Dinosaur extinction narrowed down to I think within 30,000 years, we have a good date in the rocks.
So you can only date rocks for the most part if there’s like a layer of volcanic ash somewhere near the thing that you’re looking at because volcanic ash has these things called zircons that are easy to date with radiometric dating. So We have the extinction event has been narrowed down to like 30 or 20,000 years or something like that for the dinosaurs. But some people would argue that it was much, much faster. That’s the uncertainty of geology.
Ross Kenyon: Yeah, I remember first learning about this in Elizabeth Colbert’s The Sixth Extinction about the formation of the study of geology and these fights over uniformitarianism, which is that change happens very gradually over time. And then they would fight with the catastrophists who would argue things like meteors had a lot of responsibility for changes in geological eras and epochs.
Peter Brannen: Well, I think one of the things people were most resistant to with asteroid hypothesis and even the time scales we’re talking about for the volcanic events, which are hundreds of thousands of years the most and probably less than a few tens of thousands of years, which is still catastrophic in geological terms. People’s resistance to those sorts of mechanisms, a lot of it had to do with sort of the bad taste left over in people’s mouth from like biblical flood geology, that big catastrophic thing. Like geology is the processes you see at work on the planet today have always been happening.
And the landscapes that you see are the result of these very slow processes happening over all of Earth history. Yeah. And that was a huge insight at the time because it allowed you to realize how long it took to build up a sandstone or something like that. And sort of was like this intellectual revolution that the earth is really old and these things take forever to... The rock record takes forever to make, which is really important. But it turns out that sort of the most important events in the history of animal life have been these really sudden catastrophic events.
Catastrophism has definitely won the day these days in geology.
Ross Kenyon: You got to be careful because reading your book and Elizabeth Colbert’s book and other things in geology, learning about the fights over plate tectonics, which by the way is super recent.
Peter Brannen: It’s crazy how recent it is.
Ross Kenyon: But these fights in geology get nasty.
Peter Brannen: Really nasty. In fact, especially with the dinosaur in Cretaceous Mass Extinction, People like lost personal relationships over this because they would take one side or the other. And I asked when I interviewed one scientist for the book, he started off with this caveat that he’d be happy to answer questions about any the mass extinctions except for the KT because it’s too political. So he didn’t even want to comment on it. I think that’s changing a little bit.
Christophe Jospe: Now I understand why you rushed us to present day. So let’s go there, Peter. All right.
Ross Kenyon: Oh man, where do we even start? I mean, you have a lot of stuff about coral reefs. I’m wondering what we might be able to learn from there, but we also want to broadly talk about the Anthropocene. So I guess as the example from your book that freaked me out potentially the most, how in danger are coral reefs and what does it look like when oceans have lost coral reefs in the past?
Peter Brannen: Coral reefs are in an incredible amount of danger. On anything like a current emissions trajectory, you should be getting coral reefs things in order and saying goodbye and visiting them soon. Because by the second half of the century, they should be mostly In a lot of trouble. And that’s because of we’re doing a couple of things. We’re warming the ocean, which we’ve seen in things like Great Barrier Reef and even the last couple of years, these devastating bleaching events when corals eject their symbiotic algae that gives them food. They do that when it gets too warm.
And then they basically starve and you get these bleaching events where it’s funny, actually, I saw this reef biologist posted this picture of Google has all these, what do you call them, wallpapers for like your phone that just come like as factory presets. And there are all these pictures of coral reefs and like half of them were just like bleached reefs that I don’t think they realized were just pictures of dead reefs.
Unknown speaker: Beautiful, white.
Peter Brannen: Yeah, exactly. It was sort of picturesque, but there’s like no fish on it and not. Yeah, so bleaching is a big problem. And then acidification, which is what happens when too much CO2 reacts with seawater, makes the oceans more acidic. It’s actually pretty complicated. It reduces the amount of carbonate in the ocean and makes it harder for coral reefs to build their skeletons. And so that’s really bad for them too. And reefs tend to get wiped out in all of these mass extinctions. And acidification and warming are pretty good explanations for why that happens.
So Given that we are acidifying the oceans faster than we can tell in at least 66 million years, it seems like they’re in a lot of trouble.
Christophe Jospe: The oceans are so fascinating. I think it’s also oftentimes forgotten that the oceans are doing humanity of the modern age a real favor because we’re just ejecting all these fossil fuels into the atmosphere. And the oceans right now are sucking up about half of them. But at some point, the ocean will slow down and Yeah. And so just giving it this gigantic kick that we don’t really know where it’s leading.
Peter Brannen: Even if we stopped emitting tomorrow, I don’t think we know what we’ve set in motion in the ocean. We’ve put in 25 zetta joules of energy into the ocean. You don’t hear the prefix zetta very often. That’s because it’s one with 21 zeros after it. It’s an incredible amount of energy we put into the ocean. I think we don’t know what we’re doing.
Ross Kenyon: I think we’re going to anachronistic pre-Cambrian slime walls or whatever. I hope not. What comes after the coral reef? Is it just the ocean in the shallows are much less vibrant? Does all the life that depends on coral is just gone? Does something move in to replace it?
Peter Brannen: That’s a good question. I mean, today I think the figures, coral reefs supply something like 25% of the ocean’s biodiversity. But you don’t lose all ocean life after the reefs collapse. You have a pelagic species. You have a pelagic species, yeah. So like the big Dunkelosteus, the scary Devonian guys, I think 40% of them get wiped out when the reefs collapse in the Devonian, but they make it till the end of the Devonian until there’s this big ice age. So you do get stuff that survives. And often because there’s this constant flow of CO2 into the atmosphere and gets absorbed into the oceans, there are usually things that precipitate CO2 out of the ocean.
So it’s like bacteria took that role after the Permian mass extinction. And sometimes in really extreme events, you’ll just have these like calcium carbonate fans where it’s not a biotic fabric at all. It’s just the stuff had to precipitate out of the ocean. So it was just like a laid down as limestone and there was nothing, nothing living that was doing that. So yeah, for the most part though, animals have been mediating the role of turning CO2 that comes into the ocean, turning into limestone. But if you get rid of animals, it’s still going to happen.
This is getting very wonky chemically.
Christophe Jospe: So keeping with wonky chemical tangents, I’m really interested in your definition of fossil fuels.
Peter Brannen: Fossil fuels are... What happens when life gets buried and gets preserved in the rocks for a long time? So, yeah, everything we’re burning today was once, you know, plankton bloom in the Permian or a big jungle in the Carboniferous. And rather than getting decomposed at Earth’s surface, it just so happened that the conditions were right, that it could sink into the rocks where it could be preserved for hundreds of millions of years. And we are... Digging up that old plant matter and releasing the sunlight essentially that it captured hundreds of millions of years ago for energy and undoing the photosynthesis that it did in life by releasing the CO2 that it took out of the air to make organic matter.
So we’re sort of doing the same thing that all animals do. When you eat food, you turn plant matter into CO2 and energy. Humans are doing the same thing only with all the plants that have ever been buried in Earth history.
Ross Kenyon: Did you want to follow up or do you want to go to the end place to see?
Christophe Jospe: Small follow up from that. So that’s a great definition. And I think that frames fossil fuels in a way that our listeners might not always think about. And it’s interesting thinking about some of the variations of where fossil fuels are stuck. You know, I was driving here to get to Denver and, you know, going through Carbon County and see all of these fracking wells. Yeah. You know, also through coal country in Wyoming where we’ve got that sub-bituminous or lignite coal or like, you know, Powder River Basin coal. All these different types of fossil fuels which have manifested themselves in different ways.
Some are very sort of close to the surface. Some you need to dig deep down on. So, I’m just kind of curious in terms of the extinction, mass extinction’s role in generating these fossil fuels and some of the varieties around them.
Peter Brannen: Yeah. So a lot of the fuel, a lot of the natural gas that we frack today is basically, I think I described as like the victims of the late Devonian mass extinction because you have these shallow seas that are covering the Eastern US and the middle of the US that go anoxic. And so you have these huge plankton blooms that die and they’re so massive that they cause these dead zones. And so they fall to the There’s no oxygen, so they don’t decay. So you preserve that organic matter. And so you do that for a long time and in completely anoxic conditions and you have tonnes of plant life that’s being buried.
That’s left behind tonnes of natural gas to frack in these black shales. Things like the Marcellus and all those are from the late Devonian and it’s because the oceans were so stressed from all this dead life. And it’s funny, I have these Google alerts for things like Permian-Triassic to try and find out new studies that are coming out. And a lot of times it’ll be these news alerts from oil companies where it’s like, oh, new Permian-Triassic oil play discovered in the North Sea and it will be associated with these mass extinctions.
Yeah.
Ross Kenyon: Peter, why don’t you catch us up to the present? What characterizes the newest of the mass extinctions or proposed mass extinctions?
Peter Brannen: Yeah. So dinosaurs go extinct 66 million years ago. And then ever since then, it’s sort of been thought of as the age of mammals, which at least one dinosaur expert disagreed with me about because there’s more species of birds than mammals today and birds are dinosaurs.
Ross Kenyon: Yeah, like have you ever seen a pelican? These things are straight up dinosaurs.
Peter Brannen: Right. Yeah. So there’s more birds than mammals today and birds are dinosaurs, which is actually true. It’s not just like something cute that paleontologists say. But nevertheless, we are sort of So if you take it as a given that we’re in the age of mammals, modern humans show up around 300,000 years ago on this ice age world that’s filled with things like woolly mammoths and mastodons and giant ground sloths. And in North America, there are camels and lions and all sorts of crazy stuff. But we show up in Africa and then we spread out over the planet.
And as we do, there’s sort of this eerie shadow of extinction that follows us where every new continent and landmass and island that we show up on, all the big stuff disappears. So... 50,000 years ago, when the first people show up in Australia, you lose everything that’s over 100 kilograms, these giant wombats and giant monitor lizards and all sorts of crazy stuff. And then around the time when humans show up in North America, you lose all the stuff that we think of as Ice Age stuff. So mammoths and mastodons and the stuff I mentioned before.
And then that continues up to the present day where, you know, A thousand years ago or a few hundred years ago, as people spread out across the Pacific and Madagascar, every single island and landmass they show up to, either from direct killing or the changing of a habitat or by introducing invasive species like rats and pigs and stuff like that, you tend to lose big stuff and a lot of little stuff too. And then that comes right up to the modern day where now we sort of have our foot on the accelerator and we’re Every year, industrial fishing trawlers plow over something like two continental U.
S. ‘s of seafloor every year, and we’re breaking up the rainforest. So we obviously have this huge influence on the environment today, and it’s been proposed that we’re in another mass extinction on the scale of these apocalypses I talk about in the book. I think whether that’s true is actually kind of an interesting, complicated question. Because I just detailed all this devastation, which is totally true. But it’s also true that the events I talk about in the book are so insanely off the charts that we’re not quite there yet, which is the good news that we still have time to avert sort of the end times, which is encouraging.
I think in historical times in like the last few hundred years, it’s... Something like one to 10% of species have gone extinct. So that’s really bad. And it’s appalling that we have the capacity to do that, but it’s not 96% like the Permian. And in the oceans, not many species at all have disappeared. We take something like 270,000 sharks out of the water every day, but there’s no shark species have gone extinct yet, which just shows you how resilient and amazing life on earth is and also how devastating humans can be.
But What I think is sort of a risk in talking about the sixth extinction when people are just presented with it, like a huge mass extinction, as they get fatalistic, they think the world’s already over. And these are actually like the last few decades when we can do something about it, when we can actually avert, you know, the worst case scenarios. So... I kind of emphasize in the book that it’s not over yet. We still have time to save the planet. But it is worrying that, especially going forward, where in the past a lot of our damage has been done by hunting, that now we’re starting to pull these levers that are really responsible for the worst things that have ever happened in Earth history, these big injections of CO2.
And so before we go too far down that road, because we know where it leads, we should consult the rocks and learn what they have to tell us.
Christophe Jospe: I like your optimism. I want to throw a little bit of cold water on it, but I also am an optimist, Peter. Also in my drive going through the Carbon County and other places, I was in Yellowstone and noticed a lot of dying trees. And the trees are dying because we’ve got the mountain pine beetle that devastates these areas. And the trees had previously been happily photosynthesizing and storing carbon. Now they’re not. And it brought to mind all of these things which are happening, forest fires, methane releases, the natural carbon cycle being exacerbated because of these feedback loops that we talked about earlier.
And I’ve had a sort of bone to pick with the climate community for a while, which is saying, you know, we need to be net zero emissions by X date, 2050, whatever. None of that matters when the carbon cycle because of human activity is getting more active. So it’s really like... In this Anthropocene where humans are waking up and realizing that we need to manage not only our emissions, actually we need to manage the atmosphere, which is driving all of that. So I’m just curious, both what can we learn from the mass extinctions in terms of managing the carbon cycle, which we’re waking up to, seems to be the most important thing in averting crisis?
Peter Brannen: Yeah. I don’t think you have to go all the way back to the mass extinctions. I think we’ve learned from just sort of geological history that the Earth doesn’t like being in sort of like half states, like in disequilibrium. It likes being in one state or the other. And right now we’re in this ice age world. And we’re possibly kicking CO2 up to a thousand parts per million by the end of the century. And two weeks ago, I was in the Bighorn Basin in Wyoming where they’re studying the early age of mammals.
And there are crocodiles and hippo-like animals and palm trees in Wyoming. And there are palm trees in the Arctic at this time. It’s an incredibly warm world and it’s about a thousand parts per million. And the models that we use to project the future, we can’t make work on getting the planet that warm back then. There’s some feedback we don’t have included in that. And it might be that when you make the Arctic really warm, you do get this feedback in the methane cycle, which is part of the carbon cycle, that explains how at only that level of CO2 you get this planet with crocodiles in the Arctic.
So yeah, we are threatening to kick the planet into a state that You know, Greenland doesn’t like being half melted. It’s either, the ice is either there or it’s not. And it likes finding an equilibrium point. And once you take ice off of Greenland, then you have vegetation, which has a, you know, it’s darker. It has a higher or lower albedo. I always forget how that works. Lower. Lower, yeah, yeah. It has lower albedo. So it’s absorbing more sunlight. And then you get in, you know, you might have swamps there.
And so you would get these crazy kickbacks in the carbon cycle where then, okay, you’re out of this ice state and now you’re in the warm state.
Christophe Jospe: At least the naming convention will finally not be upset.
Peter Brannen: Yeah, right. But again, a lot of problems with this is that I need to remind myself that I’m thinking in geological terms and that it takes a long time to melt all of Greenland, but geologically it doesn’t. It takes a few thousand years, which is nothing. And in the meanwhile, humans have to deal with these coasts that keep moving around and weather that keeps getting weirder and weirder until the planet sort of finds its happy place.
Ross Kenyon: And it’s unique among the mass extinctions that we’re both the agent and its victim potentially unless we can avert it. And we’re aware that mass extinction is happening. Right. And we’re trying to figure out exactly how to prevent it, which is a surreal sort of like reflexive process.
Peter Brannen: Yeah. Well, we might not be the only ones that are the agent and the victim. Actually, in the Devonian, the tree that’s considered most responsible is this like it’s this thing called Archaeopteris, which is really confusing because it’s very similar sounding to a dinosaur, too. But it both caused this ice age and then is never seen again afterwards. So it might have wiped itself out. But by then, land plants were enough established.
Ross Kenyon: That’s my personal favorite of all the mass extinctions. One of the common things that I’ve heard that I wanted to write something against this for a long time is that people who are skeptical of climate change will say the earth has been changing constantly. And this is a natural process, which is true, but I’ve never understood why that would matter because even if all the changes were due to changes in the axial rotation of the earth or from changes in how the sun works or just volcanoes were emitting a bunch of CO2 right now.
We still need to manage it because all of humanity’s expectations are built around sort of a similar world to the one that we have now. It’s like, why does it matter if it’s a human cause or not? Why does that fight always end up in that place that it’s natural?
Peter Brannen: It doesn’t. Because it’s all very scary. It takes two seconds of thinking about to realize how fallacious that argument is. As one of the quotes I have in the book is, it doesn’t matter if it comes from Volvos or volcanoes, CO2 does the same thing in the atmosphere. Are we supposed to celebrate it if it was a volcano and humans were off the hook? Cool. Yeah. And I also don’t think people think that through. Like, yeah, it’s true that life was happy in the age of mammals I was just talking about when there were palm trees in the Arctic.
But if you just suddenly superimpose that climate on a world today that’s partitioned by national borders and geopolitics, like that is a catastrophe, like on a scale that’s unimaginable, even if it doesn’t cause a mass extinction. On a civilizational standpoint, it’s a total, if you make the tropics uninhabitable, that’s going to be really bad.
Ross Kenyon: Oh, yeah. We’ve talked about this a number of times, too. The civil wars and potential genocides and the politics that react to the sort of these pressures. And I think it would be a very scary world until maybe there’s a new equilibrium. But people tend to focus on the polar bears or like New York’s going to have to build up a little higher. And you’re like, no, people are not going to have food. They’re going to be very angry. There’s going to be like right wing populace of other governments where the immigrants are going who are going to get progressively more intense in their reaction.
Peter Brannen: Yeah.
Ross Kenyon: That’s sort of what we look at.
Peter Brannen: Yeah. That’s the really scary stuff to me. Sea level rise is going to be really bad, but I kind of think it’s like a little overrated in terms of the scariest stuff from globe warming. I think the warming, it’s just going to get really warm. And that I think will displace a lot more people than sea level rise.
Christophe Jospe: Didn’t you write about the dew point in your book?
Peter Brannen: The wet bulb temperature.
Christophe Jospe: Wet bulb temperature. That’s it.
Peter Brannen: Yeah. So it’s like this absolute... There’s no way to cool off at all once humidity and temperature reaches a certain point. And the way they measure wet bulb temperature is you put a thermometer in a wet sock and you spin it around like as fast as you can. And it simulates what it would be... It’s funny in the papers it describes... This is the point at which you can no longer cool off even if you’re sitting in a dark room naked doing no work and you have gale force winds on you.
You’re still going to die of overheating. And this is a level that doesn’t get reached today almost anywhere in the world ever. But you add a little more water vapor. And then if like worst case scenario, if it was like 10 degrees of warming in the next few centuries, most of the places that are inhabited today are uninhabitable. But yeah, I don’t think we’re going to get that warm.
Ross Kenyon: We should talk about carbon removal too. I guess we’ve talked a little bit about enhanced weathering and how that might look. Are there other things that we could learn about the process of changing the atmospheric concentrations of greenhouse gases from these mass extinctions or geological history generally?
Peter Brannen: Yeah. Well, I just think it’s so cool that a lot of the technologies that people are exploring today build on our understanding of Earth history and geology and how the planet works and has behaved over Earth history. I know at Columbia, at the Lamont-Doherty Earth Observatory, a few years ago they were doing these tests. I don’t know if they’re still doing them, but using the basalt that’s under them to inject CO2 into and have basically turned them into limestone. And what’s crazy is that the basalt that is underneath the Lamont-Doherty Earth Observatory in Columbia is the Palisades that caused one of the mass extinctions I write about in the book.
And one of the ways the earth cooled off after that mass extinction was actually weathering that exact same volcanic, those volcanic rocks. CO2 went up really high. So you get more acidic rain and basalt just tends to be easier to break down. And so that was one of the ways that the earth cooled off after this warming mass extinction 200 million years ago. And so we’re looking at using the exact same rocks to do the exact same thing to pull CO2 out of the air, which I think is kind of cool.
Christophe Jospe: That’s actually a throwback to the third episode that we did on the show with Dr. David Goldberg. And that research has evolved where now they’re in Reykjavik. Or outside of Reykjavik in the Halles-Hedi power station in Iceland. And what they’re doing is tagging the carbon they’re injecting underground with C14 because it’s an isotope that they can isolate. They know it’s not down there. So if it comes back up, then they’ll know that the basalt rock wasn’t able to sequester it. But they’ve proven that the basalt rock can actually sequester 95% of the pure CO2 they’re injecting down there.
Peter Brannen: That’s really cool.
Ross Kenyon: Is there anything else that we need to cover or should look forward to? Do you want to leave our audience on a happy or grim note?
Peter Brannen: I guess there’s like two consolations in my book. One is that if you care about the long run, it’s going to be fine. In a million or 10 million years from now, there’s going to be a lot of cool creatures running around and everything’s going to be happy. In the shorter term, I think I just reiterate what I said before, that this is actually sort of like our last chance to And there’s no reason to throw in the towel yet. This is like the most exciting time to be a human.
And one of the most exciting times to be alive on this planet in the last 500 million years. So I think people should sort of be energized by that circumstance rather than depressed by it. I’m not downplaying how catastrophic humans have been or have the capacity to be. And there aren’t too many I think it’s a huge area of opportunity. I was saying before the podcast that there was a recent Nature paper that said that The CO2 removal industry has to be two to four times bigger than the global oil industry by 2050 to meet the Paris Agreement goals.
And if that’s true, that’s a big opportunity for people to take advantage of. And I hope that works out. So yeah, I don’t know. That was sort of rambling, but... I tend not to be super optimistic, so I’m forcing a lot of this.
Ross Kenyon: Yeah, just grinning right through it. Well, we would definitely recommend, listeners, check out your book, The Ends of the World by Peter Brannen. I loved it. It was definitely one of the wittier geology books I read. There’s a lot of great lines in it. And people can check out your work. You have a website. Is it Peter Brannen?
Peter Brannen: Peterbrannon.com. And on Twitter, I’m at Peter Brannon1. Because I guess there’s another Peter Brannen out there who has like zero followers and has never tweeted, but.
Ross Kenyon: That is common. Is there anything you want to say, Christophe?
Christophe Jospe: Thanks so much for listening. If it was your first time, please subscribe. Please share this podcast. Leave us a review. All the good things helps us grow.
Ross Kenyon: Yeah. Thanks so much for listening. We had a good time and let us know what you think. So thank you so much.
