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Climate Change and Extinctions: A Deep Time Perspective

Peter Brannen

Saturday, June 8, 2024

Chris (00:01.144)

Welcome back to Decouple. Today I'm joined by Peter Brannon, who is a science journalist, author of Ends of the World. And Peter, I believe you have an upcoming book. I came across your work on our Mutual Friends podcast, Nate Hagens, and decided I had to have you on. So welcome aboard and fill in the bio a little bit. Tell us a little bit more about yourself.

Peter Brannen (00:26.396)

Yeah, my name is Peter Brennan and I'm a science journalist who's been writing about earth science now for over a decade. And I really get into, you know, this geological wormhole that I've been writing about for, I don't know, the last seven or eight years, sort of through an unexpected avenue where I was writing a lot about ocean science and climate science. And then I realized that sort of half the story with climate change, at least that I, as far as I could perceive was that,

You know, we have climate change modeled and it's very theoretical and it's in the future. And that's half the discussion, but we actually have this experimental record of climate change. You know, the only way that earth has actually ever responded to, you know, huge pulses of CO2 into the air is in the fossil record. And we test models for the future on their ability to reproduce some of these events. And sometimes they can't, sometimes they can. And so I just thought that was sort of a huge undertold.

part of the climate story is sort of its legacy in the fossil record. And I guess sort of the scary part or the punchline, however you want to phrase it, is that sometimes when experiments that look very similar to the one we're doing now, different in important ways, have been run on the planet in its past, where giant pulses of CO2 go into the air over the course of a few millennia, you see all the sorts of things that we're worried about.

in our own future. And in the most extreme cases, you get these big nasty mass extinctions. So everyone's familiar with the mass extinction where the big dinosaurs went out, got wiped out. And that one is very much associated with an asteroid impact for good reason. There might be some other stuff going on there that we can get into. But it turns out that's, by some accounts, the fourth biggest mass extinction in Earth history. And there are four before it, some of them which are hundreds of millions of years older.

And for the most part, asteroids don't explain those. You can't find convincing evidence for asteroids at any of the other big mass extinctions. And instead, what you do find is these sort of mind -bending volcanic events where thousands of gigatons of CO2 comes out of the air. And if you know how to read the rocks, if you're a clever geochemist, you can analyze the fossil record and tease out what happened to the planet, how it responded to these big crazy injections of carbon into the air and atmosphere. And...

chris (02:45.432)


Peter Brannen (02:45.98)

So I thought that was a big story that was sort of undercover and I've made it kind of my niche, not quite aware the learning curve I would have to ascend to just geology. There's so much jargon and it's such an interdisciplinary thing where you have to understand the ocean and the atmosphere. And in the case of dinosaurs, even stuff from outer space, you need to know how to interpret that in the rock record. So I have just gone down this wormhole in the last few years where I...

sort of only look at what we're doing today from the context of deep time and what lessons we can draw out of Earth history and what they can teach us about our future.

chris (03:22.36)

Yeah, it's interesting in the kind of energy planning world as well. So much depends looking forward on modeling. And...

blanking on the guy's first name. It's I think Edward Box, famous statistician. All models are wrong. Some are useful. And obviously, you know, looking back in time in terms of, you know, energy transitions or so -called energy transitions, that's certainly useful. You can draw lessons and they may or may not be applicable to the future. So I'm seeing lots of overlap there in terms of, you know, the two areas that we're studying. You know, reading your book,

Peter Brannen (03:37.084)

Yeah, right.

Peter Brannen (03:49.116)

Mm -hmm.

chris (03:56.088)

I was struck with the kind of kill mechanisms of the mass extinctions, which again, we're going to get into in a little bit more detail, but just how this incredibly powerful fire ape species is essentially capable of mimicking so many of those. And even if you think about an asteroid strike, global nuclear exchange with ensuing nuclear winter might mimic that.

Fairly well. I imagine there's no bomb, no single bomb that can produce anything like it. But maybe if we kind of set everything up, which is not unfeasible and similarly kind of changes in CO2. And we're going to get into a little bit, I think, the kind of eutrophication or kind of overnourishment of the ocean. So maybe let's get into that by walking through a few of these events. I know a couple of them are kind of relying on the same mechanism. So maybe let's kind of take it.

Peter Brannen (04:22.14)


Peter Brannen (04:36.732)


chris (04:49.816)

mechanistically or chronologically or however you like.

Peter Brannen (04:51.484)


Well, there's the first two are kind of, the first four all have to do with huge derangements of the carbon cycle basically through these kill mechanisms that are intrinsic to the earth itself. Two of them are caused by these just mind bending volcanoes, but the first two are a little odd. So if I can do it chronologically, if you want, I can kind of try to run through them. But yeah, sure.

chris (05:15.)

Actually, before before you do, let's just nerd out a little bit on this concept of geologic deep time, because it is it's so mind bending. I think there's probably only like physicists, astrophysicists and geologists that really kind of get into this. I mean, of course, human beings go down to like the nano level. So there's all sorts of things that our brains are not designed to do. But in very modern times, we've become capable of. But even just establish a timeline to fit this into. So, you know, Big Bang is.

Peter Brannen (05:20.956)


chris (05:44.568)

What 13 .8 billion what walk you know, key events along the way earth forms.

Peter Brannen (05:46.428)

Yeah. Yeah, Earth forms about 4 .5 billion years ago. Life emerges maybe around 4 billion years ago. I get into that in my next book, actually, because it turns out that's sort of a carbon dioxide story, too.

chris (05:53.528)

Life emerges.

chris (06:01.08)


chris (06:04.696)

wow, okay.

Peter Brannen (06:06.34)

So yeah, life merges maybe for 3 .8 billion years ago. Great oxygenation event happens around 2 .5, 2 .4 billion years ago. Last, yeah. Yeah, so I don't like, if you talk to people who actually work on that time period, there is this pop science idea that it was like, this is actually the biggest mass extinction. And people have said that to me.

chris (06:11.352)

Great oxygenation event.

chris (06:18.264)

And is that a mass extinction or there just wasn't enough biodiversity to call it that?

chris (06:32.088)


Peter Brannen (06:33.596)

But if anything, it's an expansion of the biosphere because you don't lose anoxic bacteria. Like there's still major parts of geochemical cycles today. You just get this new expansion of aerobic life. And then actually it's at the end of the great oxygenation event that you have this massive crash in oxygen after a few hundred million years that then you see one of the biggest, you know, it's very clear that the biosphere shrinks dramatically. And then you're at pretty low oxygen for another billion years or so until you go into this...

chris (06:40.568)


chris (06:58.008)


Peter Brannen (07:04.188)

Episode of snowball earth, which is another thing I'm really getting into now, especially in my next book, which might've been caused by a decline in CO2 from the breakup of a super continent and weathering of the continents. So today we're what we are investigating weathering rocks, things like basalt to sequester CO2. That's like one of our tools. And it turns out the earth also does that on its own and it's the most effective way of sort of burying carbon over the longterm.

chris (07:07.672)


chris (07:24.024)


Peter Brannen (07:31.004)

is weathering rocks and you might've had this really accelerated pulse of it that throws you into snowball earth. There's other, you know, proposals for why you go into snowball earth. But then for some reason, you have the biggest climate catastrophe in earth history and right after that, or not right after that, but in the wake of that, you get the emergence of large complex multicellular life and then the explosion of animals in the Cambrian. So you go from this period of 4 billion years without complex life, this massive.

chris (07:57.752)


Peter Brannen (07:59.932)

episode of just completely unimaginable climate chaos. And then out of it, you get sort of the champagne cork is popped and animal life comes out. So there's people investigating what the relationship is between those two things. And, you know, NASA underwrites a lot of the research because if that has something to do with the emergence of life here, then maybe it does on other planets too. But yeah, I just said that all in a paragraph, which makes it sound like it didn't take that long. But,

chris (08:15.64)


chris (08:26.296)

All right.

Peter Brannen (08:27.1)

The tool that I use to think about deep time that I also ran through in Nate's podcast and that I use in the book as well, just because I find it so useful. There's a lot of ways of thinking about this. One paleontologist showed me a beer and he said, just like the foamy head on the top, that's all of animal life. But so you get, yeah, I mean, the other one is you hold your arms out at, so your wingspan is fully extended.

chris (08:46.168)

Wow, I like that one.

Peter Brannen (08:56.316)

And John McPhee, who is this New Yorker writer who wrote about geology said, if you took a file, like a nail file and filed off a little bit of one of your fingernails, that would be all of human history or something like that. So that's a way to think about it. The one I like is that if you imagine every footstep you take is a hundred years back and you go for a walk, you know, within a few footsteps, it's the Roman Empire and 60 footsteps after that is the beginning of recorded history. And then...

chris (09:09.592)

Right. Right.

Peter Brannen (09:26.108)

you know, I don't know, 200 footsteps after that. So you've barely walked, out of your house and sea levels 400 feet lower. And there's camels and lions in North America and there's an Antarctica's worth of ice on North America. And, you know, the world is totally transformed. You've walked a couple hundred footsteps and then you ask how much further would you have to walk to the beginning of Earth history? And you know, you might think it's a couple of miles to the dinosaurs and the trilobites, but you'll

You'll be at the origins by sunset or something on this walk, but you'd actually have to walk for 20 miles a day for almost four years to cover the whole history. And, you know, so another reason why I think thinking about what we're doing on the planet today in this context is that these sorts of climate perturbations and carbon cycle perturbations that we're seeing in the last 200 years, you really have to...

travel pretty far back on this walk through Earth history to find anything comparable to at least the rate of change that we're driving on the planet now. So that's why I think it's so important. You can't really understand how radical the experiment we're running on the climate is unless you put it in this deeper time context and realize how out of equilibrium the global industrial experiment on the planet is.

chris (10:31.)

Mm -hmm.

chris (10:45.464)

Right, right. So, you know, like the Holocene has been this great sort of period of stability in which human agriculture has emerged and, you know, our historic memory anyway. And of course, the great advances in human well -being, I guess, with the Industrial Revolution. Is there something kind of similar at play in terms of the emergence of multicellular life and the Cambrian explosion? That Earth's chemistry kind of stabilized such that...

Peter Brannen (10:51.164)

Mm -hmm.

chris (11:09.208)

you know, life with all these pulses of extinction and radiation could occur. Like was the atmosphere just like ridiculously different? Or I guess it's hard to have life under a snowball or like global glaciation, but.

Peter Brannen (11:17.564)

Yeah. Well, the earth has this dramatic thaw after snowball earth that's almost hard to describe. You know, people talk about the freeze and I mean, people, geologists do, I don't know how much people are talking about snowball earth. But the way the earth escaped from that basically, you know, death sentence of being completely locked in ice was that the whole world was encased in ice possibly. There might've been some open water at the tropics that's debated.

chris (11:29.816)


Peter Brannen (11:47.356)

But none of the CO2 was getting, so you don't have much photosynthesis, you don't have much rock weathering because everything's covered in ice. So you're not burying any CO2, but there's still volcanoes poking up above the ice, putting it up into the atmosphere. And so you suddenly rapidly melt out of snowball earth because CO2 has gotten to this threshold where it's not getting removed from the atmosphere, but it keeps getting added, where it might've gotten up to something like a hundred thousand parts per million or something totally mind -boggling.

chris (11:58.712)


chris (12:10.68)


Peter Brannen (12:15.1)

And then the planet flips and you go into, you know, the whole thing melts in the matter of a couple of millennia and the, the ocean's covered in a mild deep, like freshwater lid. That's 150 degrees Fahrenheit of water. So it's just like this completely crazy thing. Eventually things even out. And then you get these sort of blob jellyfish sort of world called the Ediacaran, but that's not the Cambrian yet. And those might not even be animals. They're just sort of these weird experiments in multicellular life.

chris (12:30.232)

Wow, wow.

Peter Brannen (12:44.796)

And then you do get this explosion of complex life where things develop shells and start developing eyes and start hunting. And there's that arms race and all this stuff. And I do view sort of what we're doing today is maybe analogous to that. It might've been the rise in oxygen or it might've been an influx of food that powered this explosion of sort of biotechnology.

and it wiped out this world that existed before this sort of placid jellyfish world or jelly world got wiped out by this insane burst of energy and biological innovation. I mean, that's sort of the best case scenario for us is that we are at the dawn of sort of a new Cambrian and the earth's not going to look the same after this. And we'll learn to live in sort of a, something that makes sense in a long -term perspective, like, you know, the birth of animal life was a good thing.

chris (13:42.616)

Mm -hmm.

Peter Brannen (13:43.772)

Or the alternative, the much worse option is that we more resemble one of these big volcanic events that I mentioned, where it's just this burst of energy and CO2 and we wipe ourselves out pretty quickly. So I think those are the two kind of options if we have precedence in Earth history for what we're doing and we have to kind of choose which way we're going to go. Are we going to be a sustainable phenomenon on the planet or are we just going to burn ourselves out?

chris (14:08.248)

Right, right. Well, let's let's walk through the more recent mass extinctions you mentioned. And again, I think the mechanisms are really kind of what what interests me, although I'm sure there's lots of fun little kind of details and little side tangents. I love I love those, too. So because I think that the the eutrophication one was really interesting, but I think the first one.

Peter Brannen (14:19.42)


chris (14:27.896)

If I studied your book well enough and or to vision, CO2 actually goes really low. So yeah, just just walk us through that because that actually I guess talks about some of the potential kind of regeneration of the planet in terms of going down on CO2, if I'm not incorrect.

Peter Brannen (14:41.436)

Yeah, so this is after the Cambrian, like 100 million years or so after the Cambrian explosion. So animal life is trying to find a footing. It's still a totally alien planet. Pangaea is hundreds of millions of years in the future. The continents haven't come together yet to make Pangaea. There's not really any life on land. There might be some tiny little unrecognizable plants sort of at the edge of the water's edge, but...

In the oceans, you do have this really vibrant world of things that look like horseshoe crabs and these big squid with cone shells and stuff like that. It's a pretty alien world. But life is doing really well leading up to this extinction. And then it just gets 80%, I think 85 % of species go extinct at this extinction, or 80 % or something like that. And there's evidence for this massive ice age at the end of the Ordovician. And...

There's all sorts of evidence. You can see geochemically, you can tease out signals of the temperature dropping, but you can also see, you know, scratch marks from glaciers in the middle of the Sahara Desert today that are from this extinction almost a half billion years ago. Africa was over the South Pole at the time. There's similar features in Saudi Arabia and things. And, you know, whenever I see oil geology reports, I'm always, you know, I'm the one nerding out about the, you know, they'll say, what's the Ordovician -Sloarian boundary? I'm like, that was the big extinction. But...

chris (15:50.008)


chris (16:07.8)

Right, right.

Peter Brannen (16:09.308)

Yeah. So why did the earth, so you go into this ice age, sea level drops by a ton. You lose all the shallow habitat where all these animals are living and the circulation of the ocean changes, which changes the oxygenation. And the cause that, you know, in writing this book, I sort of had to, find where the consensus was heading. And the, what most researchers were talking about was the weathering of the early Appalachian mountains, which were just forming over the tropics. And.

If you build mountains in the tropics, it's a really effective way, because there's lots of storms and weather there, to weather rocks, which is just what it sounds like. It's weather reacting with rocks and breaking them down. And weathering is one of the most effective ways of sequestering CO2. So you have this pulse of mountain building that's sequestering CO2. You finally pass this threshold where sea level, you know, the ice suddenly forms on Africa. Sea level drops by hundreds of feet and all this stuff gets wiped out. So that's kind of a weird one, but it does sort of have some...

relevance to today just because it has, you know, rock weathering is something we're interested in now. Yeah, and it shows you that thresholds, you know, we're worried about the temperature going up too high, but there's also, this is a case where you pass a threshold and, you know, it drops too low and things totally change. Because in earth history, we sort of, we look at these plots of temperature and CO2 to like 2100 and

chris (17:14.232)

in terms of geoengineering. Yeah.

Peter Brannen (17:38.14)

We have this idea that everything's just very linear. And for the most part in our history, the changes have been kind of step changes, threshold sort of changes. And so that seems like that's what was going on here.

chris (17:45.08)


chris (17:52.088)

Do you think that linear extrapolation is that just the most locked in simplistic way of human prediction? We do that everywhere, unless we activate that systems to thinking and try and reason and logic through and apply previous lessons. But it's just wild to me that that's the basic mathematical function that our brains default to.

Peter Brannen (18:13.532)

Yeah, I mean, I think those models are like very well supported and maybe it's 2100 that is how the earth is respond. But.

I also think when I see it, especially when it's like, here's what our emissions are going to look like. They provide this sort of, you know, I remember one that got sort of circulated among very reputable scientists where it literally was outside of the range of uncertainty within the first year and it went to 2100. And so I don't know how, I think the future is a lot more open -ended than we tend to give it credit for. And they sort of give us this false sense of security that we, you know, we're, we're in good control of this stuff, but.

chris (18:46.2)

Right. Right.

Peter Brannen (18:55.036)

Yeah, I mean, the lesson in Earth history is that the Earth sometimes responds very unpredictably in some really dramatic ways. And the more you push on a system that is sort of further out of equilibrium, you push it, the more unexpected surprises you're going to get. And I think Earth history teaches that lesson. Yeah.

chris (19:12.248)

Right. Right.

Okay, let's let's jump into the next kill mechanism. And this is similar to I mean, again, in my framing of like, humans are activating a number of these mechanisms. This is kind of like the agricultural revolution or something or chemical agriculture, right?

Peter Brannen (19:26.844)

Yeah, no, the next one I also think is kind of a optimistic analogy like the Cambrian for us in the future. So the second mass extinction is this thing called the Late Devonian Extinction where you have about 25 million years of pulses of mass extinction, including two really big ones. And a signature you see all over the planet are these black shales everywhere.

These are a lot of the black shales that we fracked today. So like the Marcellus and the back end and the Barnet are all from the Devonian. They're all from these pulses of mass extinction. And when you see black shales, it means that the body of water where that rock was left behind, it was anoxic. There's no oxygen. And because all the life in it died and fell to the bottom of the sea and never got respired or eaten, so it just stayed there. And so those are juicy rocks to frack and things today.

chris (20:09.496)


chris (20:20.952)


Peter Brannen (20:21.948)

And so the Devonian, it seems like the ocean's repeatedly losing its oxygen and leaving behind all these black shills in the rock record. And the sort of, again, the consensus kill mechanism for this one is a very strange one, but this is sort of the dawn of the land ecosystem. This is when those little sort of pathetic plants are on water's edge that I mentioned last time, suddenly explode into trees and forests. And over the course of tens of millions of years have these repeated biolum...

logical innovations like seeds and roots that allow them to push further inland. And as they do so, they are sort of breaking up this continental rock for the first time, releasing all these nutrients like phosphorus, which we put on our crops, that washes into the rivers and then out into the ocean and it's fueling these huge algae blooms. And when algae blooms die, they get eaten by microbes and they use up all the oxygen in the water column. And so you starve everything in the...

in the ocean of oxygen. And we actually see something similar today. And it's not because of the evolution of trees, it's because we mine phosphate rock in Morocco when we spread it in the Midwest and it washes into the Mississippi. And so seasonally, every summer, the Gulf of Mexico loses or has an anoxic zone that's something like the size of New Jersey at its biggest. And it causes fish kills and is bad for fishermen and everyone hates it. But you saw something similar in the Devonian.

chris (21:43.704)


Peter Brannen (21:50.876)

only it was caused by the geoengineering of the planet by plants. At the same time, trees sequester a lot of CO2. We're looking for some people propose them as ways to sequester CO2 in the future, plant a bunch of trees. I don't know how likely that is. But you also have this evidence for ice ages in the Devonian as well, which might be caused by this forest planet sequestering so much CO2 that it is both eutrophying the ocean and...

dropping it into these ice ages. So the reason why I said this might be sort of a positive or like a role model for us is that trees went on to underwrite the, you know, the flourishing and the whole biosphere. And eventually they found their equilibrium with the planet. But their introduction to the ancient world was really pretty catastrophic. So, and the things they wiped out were, I get into the book, but these incredibly terrifying...

chris (22:36.6)



Peter Brannen (22:49.308)

fish that were, I say in the book, they're the size of buses. Unfortunately, recently they have downgraded their size and they made them look less cool. But if people are from Cleveland or have been to a natural history museum and they see these gigantic scary fish with like guillotine blade mouths, that's usually dunkelosteus. And those are found in the Cleveland area and all over the world. And they get wiped out in this extinction and reefs go completely, almost completely extinct as well. So that's number two.

chris (23:14.52)

All right. All right. Number three and four, similar mechanism. So let's jump into that. This is crazy.

Peter Brannen (23:20.156)

Yes, and sorry I'm taking so long and that I went into that tangent about snowball art. That's just because that's what I'm working on now. But okay.

chris (23:25.816)

No, no, okay, just kind of tangent. I'm going to meet your tangent with another tangent. So I briefly studied glacial geology and before that I'd been a mountain man, actually guiding hunts in the Yukon. And so my professor was hiring a logistician for a geologic expedition to look at the Toby formation in Western Canada. And my marks weren't great in geology, but I had the most credibility in terms of like fending off grizzly bears. And we were going into the Purcells, this mountain range. And I had to over -

Peter Brannen (23:38.012)


Peter Brannen (23:43.64)


Peter Brannen (23:51.26)

Yeah, yeah.

chris (23:55.722)

geologic maps, topographic maps and figure out, you know, plan routes to where this formation was because it was a totally different. I think it's like a

almost a billion years old. Anyway, and what we were looking for was drop stones. So, you know, when a glacier picks up some stones and goes over water, those stones fall out and they leave a particular mark in the sediments. And it was just like insane looking at these near billion year old rocks for these impressions of stones that had fallen off a glacier to try and confirm snowball earth. So anyway, I've got this tie in. So I've got all the time in the world for snowball earth, but.

Peter Brannen (24:03.804)


Peter Brannen (24:10.78)

Yeah, yeah.

Peter Brannen (24:18.012)


Peter Brannen (24:22.812)


I have another tangent there, but I'll restrain myself. All right.

chris (24:29.624)

Okay, maybe we'll get into it after. Okay, okay. For the listener's sake, let's talk about big ass volcanic eruptions.

Peter Brannen (24:36.056)

Okay, yeah. So the third mass extinction is the end -permeant mass extinction. It's 252 million years ago. So the first two were at 445 and 375, and then there's one at 359 too, that I sort of included in my last discussion. But the next one is at 252 million years ago, the end -permeant. It's by far the biggest mass extinction on Earth. And, you know, it's number one with a bullet. It's way bigger than any of the others. It almost needs its own category.

You do have an ecosystem up and running on land, so you have trees and big lumbering reptiles sort of things, but dinosaurs are still tens of millions of years in the future. They come after this extinction. You have things that look like reptiles that are actually more closely related to us. So it's funny that there's sort of this trope that mammals didn't really get their shot at the top until after the dinosaurs go extinct hundreds of millions of years in the future of this extinction. But that's actually, you know,

Our line actually dominated the terrestrial ecosystems at first. They weren't quite mammals yet. They were still sort of, but they had branched off from reptiles already. And some of these were really scary looking things. There were the gorgonopsids, which were the top predators, some of which had teeth that were longer than T -Rex teeth. They're sort of like tiger, they're like very agile, athletic looking animals. They all get totally wiped out. In the ocean, you know, reefs have bounced back by this time.

A good place to see what a Permian reef looks like is at the Midland, the Permian Basin Petroleum Museum in Midland, Texas, where they have a great diorama because the Permian was an incredibly prolific oil producing time, especially in Texas. But then at the end of this extinction, or at this extinction, reefs get totally wiped out. It takes tens of millions of years for them to recover.

What's really eerie in the oceans is that your listeners might be familiar with these things called stromatolites, which are sort of, you might know about them from the pre -Cambrian, these mounds of bacterial slime that cyanobacteria make that some people point to as sort of the first fossil life in the fossil record. They disappear completely for the most part in the age of animal life, because once the seabed has animals burrowing and stuff, you just, you can't grow these like microbial mats.

Peter Brannen (27:00.124)

except for in the wake of the Permian mass extinction, you see them sort of come back all over the planet. And it's because animal life gets so wiped out. Insects take a hit and they're only, you know, the only mass extinction that really affects insects. You see these weird, you know, evidence that things have gone really wrong. There's this thing called the fungal spike, which is sort of in strata of the extinction all over the world that people think might just be, you know, some people think it might just be from like things rotting and fungus kind of taking over the planet.

chris (27:06.36)


Peter Brannen (27:29.212)

So it's really gnarly and it takes about 10 million years for the planet to recover. And because this one was so extreme and because the asteroid had already been sort of validated as an extinction mechanism, people sort of scoured the planet looking for an evidence for an asteroid impact at this event. And there isn't any convincing evidence for an asteroid impact, but instead there's this massive area of Siberia called the Siberian Traps, which...

were these lava flows that erupted on a continental scale. And they're dated precisely to the mass extinction. And to give you some scale of what these volcanoes actually were like, so they're not like Mount Fuji or anything like that. It's more like Iceland would be a good way to think about it, where it's sort of this bird -like fissure eruptions just happening over a whole continent. But enough, the magma and lava that's...

chris (28:13.688)

Mm -hmm.

Peter Brannen (28:22.812)

associated with the Siberian traps is enough to cover the United States kilometer deep in lava. So not even like in inches of ash, we're talking that's the lava part. So that obviously is very extreme. And the fact that it happens at the same time as the extinction is, you know, pretty telling. And they would have been putting out all sorts of bad stuff, like stuff you'd have in a World War One battlefield, like there would be chlorine gas and, and,

chris (28:31.352)

Right, right, right.

chris (28:49.336)


Peter Brannen (28:50.94)

mercury would have been coming out of volcanoes, you might've had mercury poisoning and sulfur dioxide and things that would have destroyed the ozone layer. But the biggest by far, the biggest signature you see from these eruptions is a massive spike in warming and a massive sort of derangement of the carbon cycle because they were putting out so much CO2. Volcanoes put CO2 out all on their own. It's the second most abundant gas they put out, but these volcanoes were also burning through

basically one of the world's largest coal basins in Russia. And we're just igniting, you know, limestone, natural gas, coal, anything they could touch and injected something like, you know, the estimates can be a little insane. Some of them are like tens of thousands or like 30 ,000 gigatons of CO2. The highest one I've seen is 120 ,000 gigatons of CO2, which is...

chris (29:21.752)


chris (29:44.088)

And for comparison, how much do humans put in every year?

Peter Brannen (29:46.652)

Yeah, so every year we put 40 every year. And I think we've put, is it one or two? I know if we burned it all, sort of all economical fossil fuels, it would be 5 ,000 gigatons. So this would be like, we burn all the fossil fuels and then for some reason we just start burning limestone for fun on a continental scale and we do it for thousands of years. But I guess the reason why it's even relevant to talk about this thing in the same conversation.

chris (29:59.768)


chris (30:10.232)


Peter Brannen (30:16.284)

what humans are doing, is that this happened over the course of something like 30 ,000 years. And as best as we can tell, the rate is faster today. And for things like ocean acidification, the rate is actually what matters. If you put a lot of CO2 into the air over a long time span, the planet has ways of scrubbing it from the system. But what we're doing is jackknifing so extremely that we can actually reproduce some of the effects of these extinctions. So like ocean is...

The ocean's gotten 30 % more acidic since the Industrial Revolution. If you project that into the future, you start matching some of these crazy geological events pretty quickly. And you know, RCP 8 .5, three centuries from now, we're not going to do it, but I think it's projected like 10 or 12 degrees of warming. And our best estimates for the Npermean mass extinction is 10 degrees of warming. So the fact that we could even reproduce what it took an entire continent of volcanoes to do is really kind of mind -bending.

And the scary thing is, you know, this is sort of the, what happens when you turn it all up to 11? What does the earth look like? And it's the worst thing that's ever happened. The oceans lose all their oxygen or not all, they lose about 50 % of their oxygen. It gets 10 degrees warmer. You acidify the oceans and basically the fossil record doesn't recover for 10 million years. So that's sort of like, worst case scenario. We know what that looks like in the fossil record.

chris (31:37.304)

Right, right. That that's that about, you know, I said acid levels rising 30 % in the oceans is pretty, pretty wild. It was it was higher in the Permian and where there are no fossils, they're forming a because there was no creatures around and B because they just couldn't form shells or what's the

Peter Brannen (31:53.82)

So the role of acidification in the extinction is like I went to a geologist's office and he showed me he had this chunk of limestone from China that he had sort of chiseled out and had polished that covers the extinction layers. And you see this like very shell rich, happy world at the bottom part of it. And then there's sort of this like uneven surface that looks like it was sort of etched into it.

chris (32:09.432)


Peter Brannen (32:22.556)

And then you have this like boring mock on top of it. And he thinks that's evidence for, for acidification. It's very hard reconstructing what actually like, we have a few layers and we have them bounded in time by a few tens of thousands of years. And we know everything goes haywire and teasing out what is the actual kill mechanism. And is difficult. But certainly there would have been massive acidification and you do see things like reefs get totally pummeled with what's kind of crazy though is like the planet.

overcorrect so much in the wake of this that then you have just torrents of weathering on land because it's super hot and there's tons of storms that then you just flood the oceans with alkalinity. So after the warming acidification part, you get these just crystal fans of aragonite on the sea floor that is just like calcium carbonate crashing out of the ocean in the wake of it. So it takes a while for the planet to sort of come back from this crazy seesawing after the extinction.

chris (33:00.248)


chris (33:22.328)

It's wild because I think most of what we hear about are positive feedback mechanisms for climate change right now. And I guess as you move out centuries or millennia, that was interesting, just like the ferocity of storms interacting with rocks speeds up weathering. I'm a medical doctor, so I'm just thinking about homeostasis is my frame with which to understand this. Now, the Gaia hypothesis is out there suggesting that this is all one big integrated system, that life sustains itself by creating the circumstances in which it can live and thrive.

Peter Brannen (33:27.28)


Peter Brannen (33:41.692)


Peter Brannen (33:45.468)


chris (33:52.282)

But what you're saying is these are these are violent swings. This isn't just you know getting a mild fever and returning to normal in a few days by shifting a couple degrees.

Peter Brannen (33:55.74)

Yeah, I mean that might be the -

Right, right. I mean, that might be, but does it? Maybe it's not the warming. Maybe it's the extreme swings faster than life can adapt to. But yeah, there are interesting feedbacks. Like one result of the ocean losing its oxygen is that it gets a lot easier to bury carbon in it, which cools the planet again. So there are these weird feedbacks. And if sea level goes higher, you have more space to bury the carbon and that can cool you off. And so there's all sorts of weird counteracting feedbacks.

chris (34:28.376)

And like when you talk about extinction, right, like if if like a fraction of a percentage of a species endures, then they didn't go extinct. Like, are we talking like just in terms of I don't know biomass or the amount of life dropping like we had a mass extinction that's a certain percentage of species going extinct. But what does that actually look like in terms of like, I don't know, the biomass of creatures pre and post? Or do we have a sense of that?

Peter Brannen (34:36.924)


Peter Brannen (34:46.524)


Peter Brannen (34:51.548)

That's a good question. I mean, it looks really, the fossil layers immediately after the mass or the N -permean look pretty like eerily kind of vacant. You might find this like really weedy clam that's the same species of clam on the other side of the planet. It's just these mono sort of monoculture weedy species, but it does, I mean, it seems like there's a pretty big drop in biomass or it just reverts like bacterial biomass.

chris (35:18.936)

Right, right. interesting.

Peter Brannen (35:21.628)

But yeah, if you hear like, it might not sound that impressive. I mean, it sounds impressive. 90 % of species on earth going extinct, but a species that survives might have 99 % of its members wiped out and it still makes it through. To wipe out an entire species is really a pretty extreme thing. And to wipe out a family, so families of animals of life go extinct as well, which means that not only does every individual member in the species.

have to go extinct, but all the species in that family have to go extinct. And you have these huge chunks taken out of basically the tree of life, especially in the end of the...

chris (35:58.328)

What's a contemporary example of a family, just for a frame of reference?

Peter Brannen (36:01.404)

that sometimes I get my phylogeny wrong. I just know that it's, it's higher than a genus.

chris (36:08.312)

Right, right. Like hominids or something, I guess, for back when there were a few different kind of homos or humans.

Peter Brannen (36:14.428)

Yeah, let's see.

Well, my search isn't, I don't want to misspeak. It's pretty high up there in the phylogenetic tree though.

chris (36:19.96)

I'm putting you on the spot here. Yeah.

chris (36:26.104)


chris (36:29.784)

We can get in the show notes for the nerds afterwards. Yeah. OK, so last one.

Peter Brannen (36:30.044)

Sorry. All right, yeah.

Peter Brannen (36:36.86)

Okay, so yeah, like Canada with like the species that has like foxes and dogs and all that stuff, that's a family. Yeah. And coyotes and all, yeah.

chris (36:44.984)

family. Okay, gotcha. Got you. All right. Yeah, let's wrap up the last extinction and then get a bit meta.

Peter Brannen (36:53.124)

yeah. So we have two more actually, but I'll skip, I'll kind of breeze through the next one because it's the same, same kill mechanism, just 50 million years later, you have this crocodilian world and reefs kind of recover. But another one of these huge volcanic provinces erupts as Pangea is breaking apart. And what's incredible about this one, at least I think, is that if you go to New York city and you look across the Hudson at the New Jersey Palisades,

chris (36:57.752)

Right, right.

Peter Brannen (37:20.188)

Those are like the Siberian traps. Those are remnants from these volcanic eruptions. And you can find the same sort of, those are sort of sills of magma that fed the eruptions in New Jersey, but you can find similar volcanic rock dated to the same time period in Nova Scotia and Brazil and France and Morocco and all over the world. And it's from this thing called the end Triassic mass extinction, where as Pangea is rifting apart, you get this big, you know, volcanic province that.

covers three million square miles. It's absolutely gigantic. And it's only after the wake of that extinction that this sort of weird lineage of crocodilians sort of takes a backseat to the dinosaurs. And then you're in the happy days of the dinosaurs for 135 million years until the big rock falls out of the sky. The weird thing about the dinosaur extinction though is that that one too is associated with, at the same time that the biggest rock to hit earth in the last billion years, as far as we know of,

The same time in India, there's another one of these continental flood basalt eruptions called the Deccan traps that weren't as big as the Siberian traps, but it was enough that it could cover the lower 48 United States and 600 feet deep of lava. So it's like not a, it's no joke. And geologists are, every field season are going out to try and tease out the relative timing of the asteroid impact in relation to these volcanoes and see, you know, what.

chris (38:33.656)


Peter Brannen (38:48.764)

what the relationship is with the extinction. The craziest idea I heard is that these volcanoes were sort of humming along and weren't that important at all. And then when the asteroid hit, it caused the equivalent of something like a nine earthquake all over the planet and actually kicked these volcanoes in overdrive. And so it was sort of this one -two punch, but it's a very contentious field of study.

chris (39:06.008)

wow, yeah.

Peter Brannen (39:12.54)

I was lucky in that covering the earlier Extinction sort of, you know, you'll find someone at the end of a hallway and a university who no one ever asked some questions. So they're just delighted to talk to you about, you know, the Devonian. But then you get to the dinosaur stuff and it's sexy and everyone wants to talk about it. So there people are kind of, it's very contentious. And I remember interviewing one guy who I told him I was writing a book about mass extinctions. And he said, I'm happy to talk to you about any of them except for the end Cretaceous mass extinction, the one that wiped out the dinosaurs, because it's too political and I don't want to like lose professional relationships. And I was like, wow, this is...

chris (39:42.52)

Wow, you'd think the carbon pulse ones would be the political ones because of the comparisons to the kill mechanism of today potentially. But contentious, I can imagine paleontologists throwing on their boxing gloves.

Peter Brannen (39:42.524)

So serious. Yeah.

Yeah. Yeah.

Peter Brannen (39:54.012)

Well, this is just the volcano and the asteroid people sort of put down roots in their camps like two decades ago and some of them are still bitter.

chris (39:58.392)

Okay, got you.

Right. So in terms of the kind of the in the very beginning when I was kind of making comparisons to, you know, the mighty power which which humans wield like how did that asteroid impact compared to, you know, nuclear bombs, for instance, or did you have any sense of that?

Peter Brannen (40:20.412)

I think it was, I mean, it was way, way, way, way, way bigger than.

I think it was, so there's, I have a line in my book and I forget what the exact calculation is, but something like the Chicxulub impact was I think thousands of times bigger than if the USSR and the US had blown up all their nukes all at once at the height of the Cold War. So it was like way beyond human experience, but yeah. And I think some of the motivation or so there's an, there's actually this interesting sort of research braiding.

chris (40:42.712)


Peter Brannen (40:55.9)

between the dinosaur extinction and the Manhattan Project. So Luis Alvarez was with his son Walter was one of the people who sort of wrote this famous paper in science, drawing the connection between this layer of what was essentially asteroid dust and.

the end of the age of dinosaurs. And Luis Alvarez was in the Manhattan Project. He wrote a note that was dropped over Japan in the lead up to the atomic bombing, signed Luis Alvarez telling them to surrender. And then his son was studying paleontology and was trying to tease out the answer to this one problem. And he says, well, I have some friends who are nuclear physicists. Why don't we put your rocks in the lab? We'll figure out.

tried to tease out some signals out of these rocks and sort of had this gestalt moment where they're like, my God, it was like a nuclear war that killed the dinosaurs. It was this asteroid impact. So they do have this kind of weird relationship.

chris (41:58.232)

And was it kind of a nuclear, I mean, obviously there's the impact and I mean, I don't even want to talk locally because I imagine the, you know, just, just the kind of thermal impact was not a small thing, but.

Peter Brannen (42:03.1)


Peter Brannen (42:08.172)

my God. So, I mean, this is one of the, like, this event is one of those things that's like truly sublime and you can't even think about it. You can't even picture it. So I remember asking one impact modeler, everyone knows those pictures where it's like, you know, an iguanodon or a pterosaur looking over its shoulder as the asteroid hits. And I asked them, what would it look like to see the asteroid impact, you know, from beyond the horizon?

And he said, the question didn't even make sense. Cause if you're close enough to see it, you instantly would have just gone blind and set on fire. Cause so much energy was released in the optical like wavelengths that you couldn't, you couldn't see it. It was something you couldn't see. And it was, you know, the size of Mount Everest and it went from the cruising altitude of 747 to the ground in 0 .3 seconds. And it didn't even, the atmosphere didn't even make a scratch on it. Like it didn't even know the app.

chris (43:01.624)


Peter Brannen (43:02.556)

It didn't know the atmosphere was there. It just hit the earth and put a 20 mile deep hole that three minutes later was replaced by a 10 mile high mountain of molten granite. Like the whole thing is just completely unthinkable. But these effects after it, people have tried to, you know, there are a few different kill mechanisms. One is that it just launched so much rock up in a space that then took these sort of ballistic orbits around the planet. And when they reentered,

would have heated, basically broiled the planet for 20 minutes. That is so extreme that even though it makes sort of sense in modeling, it seems like.

chris (43:41.272)

Well, like, like, like broiling in an oven, just all this these hot rocks in the atmosphere or in the in orbit.

Peter Brannen (43:44.156)

Yeah, yeah. So this impact modeler who I talked to, Jay Malash, unfortunately he passed away a few years ago. He tried to figure, he did these calculations and he was like, how much energy would this release? And he like did an experiment on his oven and he's like, my God, it's the same as a broil on my oven for 20 minutes on the surface of the planet.

chris (44:03.892)


Peter Brannen (44:04.188)

A lot of people are skeptical of that because it's so, I mean, it might make sense, the calculations, but it's so extreme. It doesn't seem like anything should have survived that. Although it might be telling that things that borrowed kind of did, did pretty well. But things in fresh water did generally well in the extinction too. So there might've been longer term effects where just dust was kicked up in the atmosphere and, you know, shut down photosynthesis for a while.

chris (44:09.784)

Right. Right.

Peter Brannen (44:29.66)

The asteroid hit a giant carbonate bank and would have injected something like 400 gigatons of CO2 into the air all at once by vaporizing it. It also put a lot of sulfur dioxide. It might've acidified the ocean. So there's all sorts of different competing effects. We just know it was very bad. And what do you know? Like one of the biggest volcanic events at the same time is happening. So this kind of shows you, this is why I get like almost offended when I hear people like use dinosaurs as, they were obsolete and you know, don't be a dinosaur.

It's like these things were, dominated the planet for 135 million years. It took this level of absolute chaos to knock them off. They did nothing wrong. They're perfectly, you know, adapted to their world and intelligent and capable animals. So, yeah.

chris (44:58.744)


chris (45:14.456)

Wow. And again, sorry, I'm just trying to get my time space right because that is an extraordinary long period of Earth history for a complex multicellular life. And the Cambrian explosion is like 500 million.

Peter Brannen (45:25.98)

Camera explosions like five, 10, 512. Camera ins...

chris (45:29.624)

Okay, so one fifth of that time dinosaurs are kicking ass.

Peter Brannen (45:33.884)

I mean, if you look at it in terms of terrestrial life, you first get a terrestrial biosphere 380 million years ago and dinosaurs first evolved 245 million years ago. And today there's twice as many species of birds as there are mammals. So like, this is really the, we live on a dinosaur planet. We're just here. But yeah, yeah.

chris (45:51.832)

Wow, very well adapted and weathering. I mean, it's wild at the Permian. I mean, you describe some pretty incredible mechanisms, but that asteroid impact wasn't more devastating than the Permian. That says something.

Peter Brannen (46:00.7)

Mm -hmm.

Yeah, I mean that shows you how extreme the permeant is that just through chemistry alone, things get so unpleasant that it kills more life than a crazy asteroid.

chris (46:15.8)

Mm hmm. So I know your new books, I think, dealing with carbon dioxide as its focus and I don't want you to give too many spoilers. Maybe we'll have you back when that comes up. But I am interested because, you know, this molecule is just such a potent regulator of planetary temperatures we hear. Can you just get into like the basics of why that is, why, you know, an extra few parts per million has such an impact?

Peter Brannen (46:44.412)

Yeah, I mean, I decided to write my next book, which is just about CO2. It sort of spun out of this last book, which is sort of the moral of the story was here's what happens when, you know, lots of CO2 goes into the atmosphere or lots of it decline. Here's how it's this kill mechanism in our history. But in writing that book, I sort of had to reckon with and come to understand sort of that the geochemistry of this planet is sort of fundamentally modulated through

CO2 basically. So all life is carbon. We know we're carbon -based life. And the source of that carbon is CO2. It enters the biosphere through photosynthesis or weird hydrothermal vents. It's also CO2 -based. It just uses a different energy source than the sun. But that's how CO2 enters the biosphere. And it sort of diffuses through the rest of the biosphere. And things eat things. And they release CO2 back into the atmosphere.

chris (47:18.808)


Peter Brannen (47:43.164)

And there's sort of this huge interplay of the entire biosphere as CO2 moves around the planet. And at the same time, it is keeping the climate habitable. It is.

moving between the rocks and the air and the oceans and regulating the climate. And when it goes really out of whack, you have this thing called the carbon cycle, which is basically this whole story all integrated of CO2 moving between all these different reservoirs and somehow keeping the planet habitable, which is more miraculous than you might think. There's some throwaway line in a paper I read recently where it was something like if the if CO2 burial or release was offset by like 10 percent. So if you had to

over a long geological time span, within a million years or so, you either go into a snowball Earth or like a Permian mass extinction. So we have this incredibly finely balanced sort of cycling of this one sort of crucial molecule. And so, yeah, it's kind of miraculous that, you know, the reason why Earth is Earth is because the behavior of this thing, the way it moves between the geosphere and the biosphere and the atmosphere. And it's important in the atmosphere because it is,

You know, water vapor is a stronger greenhouse gas. It traps more heat, but it cycles through the atmosphere really fast, whereas CO2 you put up there and it stays up, you know, on a human time scale forever. And so water is really a feedback to however much CO2 is in the atmosphere. And CO2 actually blocks a different part of the spectrum that's not really covered by water. So that's why it's important. You know, there's a paper that came out in Science, I don't know.

chris (49:14.136)


Peter Brannen (49:23.772)

20 years ago called CO2 is the primary knob of Earth's temperature. And that's kind of the way to think about it.

chris (49:29.92)

So that's interesting. I mean, you've also kind of nerded out a little bit about just what life is in terms of an energy dissipating system. And obviously it's an energy dissipating system made out of carbon. But I'm wondering if you can go into that and get super meta and abstract for me.

Peter Brannen (49:49.5)

Yeah. So yeah, in the discussion of sort of the origin of life in my next book, again, it's in some real heady stuff about sort of what is life doing. And there's some people who think about it sort of as, yeah, you have these, a planet has different ways of, how do I even phrase this? Basically, okay, so let's start at the Big Bang. The universe started very out of equilibrium.

chris (50:15.576)


Peter Brannen (50:17.5)

And someday it's going to be in total thermal equilibrium. And basically everything interesting can happen between those two points as that low entropy situation dissipates into a really high entropy situation where you can't do any work again, nothing interesting can ever happen. That's like the heat death of the universe. But as it's dissipating, given that the things are only going to get more disordered over time, things that accelerate that process might sort of be favored.

chris (50:20.312)

Mmm, okay.

Peter Brannen (50:47.164)

And life is an incredibly good entropy generator. It builds these little islands of order by exporting entropy into the environment around it. And basically, to make anything ordered or interesting, you need to find disequilibriums and dissipate them so that you can do work on the environment. And so the planet, early in its history, might have been really frustrated chemically and thermally. You had these oceans that were way out of the country.

chris (50:53.048)


Peter Brannen (51:16.668)

chemical equilibrium with the crust. And so you had these little like rockets of hydrothermal vents that were channeling this dissipation that they found carbon chemistry through life as a mechanism to sort of dissipate this geochemical energy. Again, whenever I talk about this, I have no idea whether I'm making any sense or whether I'm blacking out or something. But yeah.

chris (51:35.672)

No, I love it. I love it. Probably to a huge chunk of people, it makes zero sense. But to those of us who'd like to nerd out on these topics, yeah.

Peter Brannen (51:43.356)

Yeah, but there is this general trend over the entire history of life that's sort of curious where, you know, there's this guy at UC Davis, Gerard Vermeer, I think it's a Dutch name, so I'm not probably mispronouncing it, whose whole thing is about how over the history of life, power in ecosystems and in organisms has sort of progressively ratcheted up, that there is this sort of stepwise change to higher and higher energy dissipation in the ecosystem. And so,

You know, I don't, it's, I want to talk about the human story and the industrial revolution in this same story, but there's a risk of doing that and sort of naturalizing, see where this is just like nature running its course. And, you know, the last few centuries were pretty complicated and there were humans doing bad things and stuff, but it is sort of eerie to me that, you know, it is at least in line with this broader trend over all of our history where you find these larger and larger sources of free energy and get better and better at.

chris (52:19.768)

Mm -hmm.

chris (52:25.816)

Mm -hmm.

Peter Brannen (52:43.292)

dissipating them to do work on the environment and making these really ordered structures, whether they're organisms or societies or, yeah.

chris (52:45.56)


chris (52:50.104)

It feels a lot like a biophysical law and fossil fuels feel a lot like steroids in terms of just accelerating that. Yeah, no doubt. Finally, I wanted to get into a little bit your expertise prior and probably during, which helped a lot in terms of understanding more of these ocean -based worlds. I wanted to chat a little bit about the ocean because I've neglected talking and covering that and it does seem to be such a critical.

Peter Brannen (52:55.708)

Yeah, they're on, yeah, they're a PED, that's what they are.

Peter Brannen (53:16.7)

Mm -hmm.

chris (53:19.032)

buffer, I think both in terms of slowing temperature rise and NCO2. Can you give us a little explainer on that? The kind of buffering effect for temperature and NCO2 absorption, things like that.

Peter Brannen (53:27.772)

on the...

yeah. I mean, yeah. So if the oceans weren't there, I think that the temperature, if we had the industrial revolution until today and the oceans weren't there, I think temperature would have gone up over a hundred degrees Fahrenheit already. So like 90 % of the heat has gone up, gone into the oceans. They, you know, the acidification is one sort of expression of the amount of CO2 that they've absorbed.

They are this massive buffer that up until now has shielded us for the most part from the effects of what we're doing. But the more heat you jam down there, the more you're kind of playing with fire. But yeah, it's three quarters of the planet. If you spin the Google Maps the right way, you can just see the Pacific Ocean. It basically looks like the whole planet. So yeah, I mean, the oceans are kind of the regulator for the whole thing.

chris (54:20.12)

Mm -hmm.


Peter Brannen (54:31.196)

I don't know if that answers your question, but yeah. And totally neglected. I totally agree. Like 90 % of the large predators in the ocean have been taken out of the ocean in the last 50 or 60 years. They've already lost 2 % of their oxygen since 1960, I believe, which 2 % might not sound like much, but when you're talking about percentages of oxygen in the ocean, that like, again, you need these geological precedents to start being, you know.

chris (54:32.372)

Yeah. I mean, Mm -hmm.

Peter Brannen (54:59.9)

having an analog. So we've done some really, it's out of sight and out of mind. So we don't really think about it too much, but yeah, the last few cents and it goes back centuries. This isn't just an industrial thing. Like there might've been right whales wiped out in Europe, you know, a thousand years ago. And even in, even in the like pre -colonial America, as you'll see localized instances of sort of fishing down the food chain when sort of big reef fish are taken first.

So, you know, humans are the, have always been sort of the keystone species who have had these massive top -down effects on the environment. It's just now everything's so supercharged with all the power we have to change the environment.

chris (55:44.792)

changing. Yeah. And again, I think like it's fascinating hearing these numbers like the asteroid impact 400 gigatons, the Siberian traps, 100 ,000. I can't even remember the number thousands of gigatons. And so the it seems like the ocean would have a lot more capacity to buffer and absorb over longer time scales. Is that is that correct? Like, are we just heating up the top layer and?

Peter Brannen (55:56.22)

Yeah, yeah, yeah.

Peter Brannen (56:08.028)

Yeah. So it started to make its way into the deep, but there's this paper that was a summary of sort of the carbon cycle that came out recently by Scott Denning, who's at CSU, who he said, he phrased it as the deep ocean doesn't even know we're here yet. Like the ocean circulation is, you know, ocean water will sink in the North Atlantic and sometimes, you know, it'll come out in the Pacific Northwest, maybe, you know, a thousand years later.

And so what we've done, even on, not even on geological timescales, but on just sort of the, even in the surface world is, is, is too rapid for, for these things. We're acidifying the oceans faster than they can turn over. So yeah, one of the breaks, sort of the maybe emergency breaks that saved the planet in the past is that you put a lot of CO2 in the air from one of these volcanoes and it happens over millennia. So the oceans are able to turn over.

And you actually see this in an event 56 million years ago called the PETM, the Paleocene Eocene Thermal Maximum, which some people have sort of worried or wondered why it wasn't a big mass extinction because it is one of these big volcanic events. But by the age of mammals, you have this carpeting of carbonate shells on the seafloor that when the oceans turn over, they're more acidic, sort of dissolve them. And it's like an antacid that the ocean has to sort of curtail an acidification event.

which might not have existed in the Permian. That might be one reason why the Permian was so bad. But what we're doing is too fast even for that to, if we were doing this over thousands of years, then maybe you'd have this, you might see something similar in the rock record where you have this chalky sediment that turns to clay for a hundred thousand years, which is what you see in the PETM, this thing where, you know, it wasn't a major mass extinction and the planet recovered from this big infusion of CO2.

but didn't progress to a mass extinction. We're just, we're faster than that. So we like, it's even that one isn't, it's not extreme enough for, for, of an animal.

chris (58:07.8)

So I can see that you've studied this in extraordinary detail and you can just kind of whip out factoids from, you know, I could probably just say 75 million years ago, what happened? And you don't have an answer for me. But, you know, in closing, we were talking a little about modeling in the beginning and that's kind of why you love going back in time. But...

Peter Brannen (58:11.004)

no, that's, I feel bad for the listener. Yeah. Yeah.

Peter Brannen (58:25.244)


chris (58:26.776)

In terms of the accumulation of knowledge we've gotten over geologic time and geologic processes, there's tons of forecasting that sort of just seems to stop artificially at 2100. Do geologists have a sense that actually gets?

more accurate looking into time scales that more familiar with like rather than just looking at 2100 with lots of little micro uncertainties. If we're looking 5000 10 ,000 100 ,000 years away, it is a lot of thought going into that trying to project out with our geologic time knowledge.

Peter Brannen (58:55.996)

I think people are just, I mean, rightfully so, more concerned with what's going to happen in the next few decades. And there, so like, we are at, I don't know, almost 1 .5 C above pre -industrial. So we have good reason to believe based on paleoclimate studies of the Greenland ice cap, that it probably doesn't like being there at 0 .8.

chris (59:03.512)


Peter Brannen (59:21.084)

to 3 .2 C above pre -industrial. So we might've already passed the point where Greenland just doesn't like to have an ice sheet anymore. The thing is that would require, that takes thousands of years. And if you're worried about your seafront property, you wanna know how fast that happens. And so there are these processes that, I would say the most urgent things that people are studying now is,

There's especially that there's this one mechanism of ice sheet collapse called marine ice shelf, ice cliff instability, where if the ice sheets start disintegrating like this, where rather than just like sort of slowly melting into the ocean, they just become this like stack of dominoes that just falls. Then you are talking about differences in like, you know, tens of feet by 2100. So it's the over the longterm, if we keep the temperature at what it is today.

Greenland's all probably gonna be gone within a few thousand years. But it's how fast, is that gonna be too fast to adapt? And I think a thing that like the mass extinction show you is that sometimes it's, you know, sometimes it gets cold and things get wiped out. Sometimes it gets hot and things get wiped out. And it's really the pace of change if it's too fast for life to adapt. And given that, you know, there's ways of seeing sort of a global industrialized civilization is kind of like a super organismy thing.

we don't know how adaptable it is to these changes. And so it could be that we really deranged the earth system. It gets a lot warmer, but you don't get a big mass extinction. But maybe that surpasses the capacity for a networked global industrial civilization to stay upright. So there's so many uncertainties. I think the big lesson from geology is just that you point at the rocks and you say, look, we know there's someone's like, there's some.

chris (01:00:49.912)

Mm -hmm.

chris (01:01:04.472)


Peter Brannen (01:01:17.692)

Unexpected surprises if you keep messing with this stuff. This is what it looks like in the worst case scenario. And it might be a little more uncertain than we think, which is a reason for extra caution given that, you know, we're sort of taking this leap into the unknown and we both don't fully understand, you know, how society and the economy works, I would argue, and what the relationship was with energy, I would say. And we don't really understand the service system that we're pushing in ways that haven't been seen in, you know, hundreds of millions of years.

chris (01:01:47.512)

Okay, one last sort of closing question and I'm not sure if you've given it much thought, but you know, in talking about these.

kill mechanisms and means of sort of heading into disequilibrium. Do you have any thoughts around geoengineering in terms of reversing some of these processes? You know, human beings being able to act at this incredible scale and again, mimic these kill mechanisms often just through our waste products and through, I guess, like an entropic flow. What are your thoughts about the potential for?

Peter Brannen (01:02:13.436)


chris (01:02:19.608)

you know, the reversing some of these processes by just the application of doing more work or is on a conceptual levels of too driven by needing the steroids to get the work done.

Peter Brannen (01:02:30.012)

Well, so I think the people who you'll find who are most skeptical of geoengineering are sort of deep time geochemists.

There are some advocates in that community as well, but sort of, if anything, the earth, the earth history teaches you caution with stuff like this. I mean, geoengineering is a very broad term that covers a lot of things. So like this, the, you know, sulfate aerosols is one thing. I think there's things that are worrying about that, especially like we don't fully understand it. We don't really understand its impact on like monsoons and agricultural regions and stuff. And.

chris (01:02:55.224)


Peter Brannen (01:03:09.34)

could be this geopolitical nightmare. You'd have to keep doing it for thousands of years. What I think is kind of eerie is that in the big mass extinctions, at least, and maybe this is unfair to, you know, geoengineering, but it's at least sort of resonant that the things like the Siberian traps would have been putting out a ton of CO2. They also would have been putting out occasionally big pulses of sulfate aerosols and masking the effect of that warming. And it might be the termination shocks that are killing things in the mass extinctions. It might be that...

You get this pulse of sulfur sulfate aerosols that are masking the CO2 just billowing from these volcanoes. Then once those rain out, you, you know, jump four degrees C, which, you know, it was kind of the worst case scenario for geoengineering as well. I know there's some very smart people studying this. I think it's good that we're studying it like rather than just putting a lid on it, but we need to exercise a lot of, of caution. there's other ways of like, I think like, you know, just dumping.

chris (01:03:49.4)


Peter Brannen (01:04:08.156)

ground up basalt on agricultural fields and in the ocean is talked about, which is basically accelerating this rock weathering mechanism that I've been talking about that the earth does on itself over a hundred thousand years, but that we kind of want to accelerate. There's reason, I mean, geochemically, it all makes sense, but then you start breaking down the numbers and it's like, we would have to grind up like gigatons of extra rock every year, ship it all over the planet, dump it in the ocean to, you know, take out.

a 40th of the annual emissions that we're putting out. So I think whenever you look into any of these, they're all sort of like just very marginal and they seem like such a huge diversion of energy and talent and money that the number one thing we have to do is just stop putting CO2 into the air. Like that's the level we should be trying to pull primarily. And it's good that people are studying these other things, but they're never gonna account for the main problem in the room.

chris (01:04:49.24)

Mm -hmm.

chris (01:05:04.12)

Well, I mean, it's wild. There's a geologist and I may be misquoting him, but I think they were saying that human beings through, you know, mining and blowing up aggregate have an impact of, you know, moving more of that aggregate than all of Earth's weathering processes, whether it's streams or winds. But we're doing that for economic reasons. And so a lot of these a lot of these things require an enormous application of energy to do things that have no economic purpose other than maybe averting catastrophe. So, OK, Peter, we're going to have to leave.

Peter Brannen (01:05:19.996)

Yeah, yeah, right, right.

Peter Brannen (01:05:30.46)

Yeah, exactly. Right.

chris (01:05:34.074)

somewhere. I think that's a good place to leave it. Thank you so much for this backgrounder. I think it's great to sort of depoliticize some of the climate debate just by revisiting Earth's history and just getting a sense of how dynamic everything is and maybe open people's minds a little bit more to some of the experiments that we're conducting right now as this incredibly potent fire rate.

Peter Brannen (01:05:36.508)


Peter Brannen (01:05:56.828)

Yeah, well, thank you for having me. I hope I didn't get too wonky. I'm really deep in the weeds on this next book and I'm over caffeinated. So I'm sure that was kind of an information avalanche, but thanks for having me on.

chris (01:06:06.666)

Well, yeah, thanks for the teaser in terms of the new book and we'll look forward to having you back on when that comes out. All the best. Okay, hang on.

Peter Brannen (01:06:09.692)

Yep. All right. Great. Thanks so much, Chris. All right.

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