Carbon Dioxide Isn’t What You Assume It Is

When we discuss carbon dioxide, the narrative is nearly all the time that of a modern-day morality play. We hear about gigatons of CO₂ emitted, about rising international temperatures and in regards to the dire, unheeded warnings of local weather scientists. In these tales, CO₂ usually appears much less like a mute, inert molecule and extra like an evil supervillain—a malevolent pressure that has been plotting for hundreds of years to wreak havoc on our planet and spoil our lives.

But based on science journalist Peter Brannen, that dismal view is much too slender. In his first guide, The Ends of the World, Brannen chronicled Earth’s 5 main mass extinctions, charting the deep historical past of our planet’s biggest catastrophes. For his second, The Story of CO₂ Is the Story of Everything (Ecco, 2025), he has larger ambitions, taking readers on dizzying jaunts by means of deep time to reframe our understanding of what could be the most vilified and misunderstood molecule on Earth.

Inspired and knowledgeable by conversations with main planetary scientists, Brannen’s central argument is that CO₂ just isn’t merely an industrial pollutant however a key participant within the four-billion-year-old drama of life on Earth. It is the molecule that constructed our planet, forming the global carbon cycle that has regulated local weather, formed geology and powered evolution for eons. He exhibits how the ebb and circulation of atmospheric CO₂ throughout Earth’s huge historical past has performed a job in, sure, virtually all the pieces underneath the solar—from the primordial origins of life to the event of human civilization and our international financial system. From the traditional previous to the current day, Brannen makes the case that to grasp CO₂ is to grasp the very cloth of our world.

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Scientific American spoke with Brannen about what’s in his new guide, how he got here to see a easy fuel as a personality in a planetary epic and what the lengthy historical past of CO₂ can inform us about our precarious current second—and our unsure future.

[An edited transcript of the interview follows.]

How did this guide come to be? That’s all the time an effective way to begin.

My earlier guide, The Ends of the World, was in regards to the 5 largest mass extinctions recognized in Earth’s historical past. And when paleontologists have a look at these occasions what they’ve discovered is, sure, an area rock appears to have triggered the newest one, the Cretaceous mass extinction that worn out the dinosaurs 66 million years in the past. But the proof is sparse for asteroid or comet impacts inflicting the others. Instead the opposite 4—the Ordovician, the Devonian, the Permian and the Triassic mass extinctions—in addition to the handfuls of different minor mass extinctions within the fossil file, are most related to main biogeochemical occasions, normally involving large spikes in atmospheric CO₂. And these gigantic CO₂ spikes are adopted by excessive international warming and ocean acidification and all the opposite nasty local weather change results we’re understandably apprehensive about at the moment.

So this means the experiment we’re now operating on the planet by burning fossil fuels has loads in frequent with these actually grisly planetary-scale occasions, which had been actually the worst issues which have ever occurred in Earth’s historical past.

But in the midst of researching that guide, I spotted—I’m not the primary to assume this, both!—that there’s a a lot larger story to inform about CO₂ as a result of it’s not just a few industrial by-product that spews out of smokestacks or spray cans resembling methylmercury or chlorofluorocarbons, and so forth. It’s essentially completely different—virtually miraculously so. Life on Earth—what scientists name the biosphere—is carbon-based, and the supply of that carbon is CO₂. And when large portions of CO₂ are out of the blue injected into the ambiance, this causes dangerous occasions, however in “normal” instances, because it strikes by means of the biosphere and between the air, the rocks and the ocean—the so-called international carbon cycle—CO₂ is basically the important thing factor that makes Earth a particular, liveable place.

Venus is a close to twin of Earth, proper, virtually the very same dimension and bulk composition. But CO₂ behaves very in another way there in the way it cycles across the planet; it’s constructed up a lot in Venus’s ambiance that it’s brought about a runaway greenhouse impact, which is why Venus is a hell world whereas Earth is relatively an excellent place to dwell, proper subsequent door. Or, you understand, if all of the CO₂ in our ambiance out of the blue vanished, temperatures would quickly plunge and earlier than too lengthy, glaciers would unfold all the way down to the tropics, and the oceans would freeze, and many of the biosphere would perish in a “snowball Earth” episode.

So it’s a very good factor—important, in reality—that there’s CO₂ in Earth’s air, however we will completely have an excessive amount of or too little, and the quantity has fluctuated loads over time. I wished to reintroduce individuals to this factor they’ve heard about within the information and clarify its important function in shaping life on Earth.

I really like the simplicity of the title you selected, The Story of CO₂ Is the Story of Everything. But it actually swings for the fences, doesn’t it? Like, “everything” is a really sweeping time period! And I perceive what you’re saying relating to planetary habitability and the very fact of Earth’s carbon-based life. It’s more durable, I believe, to understand and convey how people come into the story, and one factor I really like about your guide is how adeptly you weave us into the material of this vastly larger image. Can you speak extra about that?

Sure, and thanks. The concept is that to essentially perceive the story of life on Earth, in addition to what’s occurring now with local weather change, it’s worthwhile to perceive this international carbon cycle I discussed; life is etched within the circulation of carbon throughout our planet. And what I attempt to do in later components of the guide is describe how all of human historical past could be seen by means of this lens—so societies and empires, as an example, are composed of flows of carbon being organized in numerous methods. And the way in which our society and politics have developed throughout the previous few centuries, it seems, is carefully linked with issues resembling how coal acquired into—after which how we acquired it again out of—the Appalachian Mountains or how oxygen acquired into Earth’s air. Seeing these connections can assist clarify the way it was that people got here to be this geomorphological pressure on the planet—and the way weird and necessary this second in Earth historical past actually may be.

What’s so extraordinary about our present second is how one species on one department of this gigantic tree of life has out of the blue found this huge, historical underground reservoir of carbon made by previous life—and is lighting all of it on hearth. And that chemical response—burning carbon-rich natural matter with oxygen to make CO₂ and launch power—is de facto the identical factor that each one cardio life, all of Earth’s animals and vegetation, and so forth, makes use of to drive its metabolism on a mobile degree. We’re simply doing this nightmarish, freakish model of it, the place we’re out of the blue combusting all of life’s leftover carbon from Earth’s historical past underneath our ft. We’ve kind of summoned these planetary forces into being by resurrecting the buried ghosts of all life that’s ever existed by bringing them again to the floor .

This isn’t actually a guide about chemistry, however I want so as to add that the one approach this all works at any scale is having a number of free oxygen within the ambiance to react with the carbon. The air we breathe at the moment is greater than 20 p.c oxygen, which is attention-grabbing as a result of, for many of Earth’s historical past, there wasn’t practically as a lot oxygen within the air. And it seems that the rise of atmospheric oxygen isn’t so simple as some microbes determining photosynthesis a number of billion years in the past. You additionally need to consistently be burying a gradual trickle of carbon—in lifeless vegetation and algae, in rocks and deep-sea sediments—to construct the oxygen up within the air over a whole bunch of thousands and thousands of years; in any other case the 2 react collectively, which attracts oxygen again down. But when you lock that carbon up within the crust, oxygen will rise. Now, previous plant stuff locked up within the crust, in these pockets the place it’s economically exploitable, is best often known as fossil gas, proper? I wager lots of people don’t know that the rationale why they will breathe is as a result of there are fossil fuels underneath their ft.

I like to think about this interaction between carbon within the floor and oxygen within the air as making a giant planetary-scale battery, the place you get two components of Earth—the actually reactive, oxidizing ambiance and the actually diminished natural matter underground—out of equilibrium with one another, with a number of potential power in consequence. Then this bizarre hearth creature out of the blue exhibits up in the midst of these two reservoirs, and over the previous few centuries, it’s discovered the right way to reunite them to extract power. So we’re speaking about an virtually instantaneous discharge of this large planetary battery that took all of Earth historical past to construct up.

So you’re saying we’re all mainly hearth imps dancing on the boundary between these two reservoirs, the oxygen-rich floor and the carbon-rich subsurface. And the event of human civilization actually boils all the way down to our getting higher and higher at discharging Earth’s battery, dissipating all of the potential power throughout this barrier.

Ha, certain, I assume that’s proper. Imagine how aliens would possibly see it, describing what completely different organisms on Earth really do. They’d most likely flag issues resembling nitrifying micro organism, bugs that pull nitrogen out of the ambiance to fertilize the remainder of the biosphere. But they’d additionally discover there’s this one outstanding creature that’s simply transferring all of the carbon from throughout the crust into the ambiance—and that’s us, clearly, the fireplace imps.

But I wish to watch out: When you discuss it this fashion, it might look like what we’re doing is simply this inevitable, pure course of, and I don’t assume that’s essentially true. This all sprung out of 1 explicit a part of the human inhabitants and is wrapped up within the particulars of human historical past—issues such because the invention of the steam engine and the rise of capitalism. What we’re doing at the moment is extraordinarily unnatural in some methods, however I simply discover it eerie that it resembles this larger image: All life finds and dissipates free power to take care of itself and develop. And human industrial civilization is doing this however at an virtually unthinkable scale as a result of it not too long ago discovered the most important supply of free power ever to exist on Earth.

What do you assume occurs subsequent? Does Earth historical past inform us? Are we doomed to trigger—and to undergo—one other main mass extinction, or is there a approach out? Easy questions, I do know.

What Earth historical past tells us is that burning fossil fuels just isn’t sustainable into deep geological time. There aren’t sufficient fossil gas reserves to maintain us indefinitely, and there’s not sufficient margin within the carbon cycle to keep away from catastrophe if we burn all we’ve acquired. Our fossil gas period is like an explosion; it might’t final perpetually. So if we’re going to endure into the geological future, we have to in a short time discover one other supply of power at an equal scale to energy society.

I believe possibly the encouraging factor is that the general public dialog, for many of the world, isn’t about debating the basic science anymore. The science is settled. It’s about completely different questions—of understanding the complexity and interconnectivity of the worldwide carbon cycle and our place in it or of political financial system and realizing the place the levers are for us to drag on this system.

To perceive the longer term and what’s going to occur, not solely do it’s a must to perceive issues such because the response of permafrost to warming or the ocean’s capability to soak up carbon, you even have to grasp people as a part of those pure methods. This is why I believe learning and speaking about local weather change is probably the most interdisciplinary factor you are able to do as a result of you possibly can’t actually divide these thorny problems with how we should always manage society and the way we should always allocate assets from these broader, planetary questions. Climate change is such an enormous, boundless phenomenon that everybody has to work on their particular components. And I wish to assume my half, the worthwhile service I can present with my storytelling, is to raised illustrate simply how large of an issue it truly is.

You talked about the science is settled, and I agree with that after all. But it appears to me there’s nonetheless lots of local weather denialism masquerading as “just asking questions” about scientific uncertainties, which could be fairly insidious—particularly when the discussions contain geological timescales.

For occasion, you write in your guide about an unnamed good and savvy nonscientist good friend of yours who fairly accurately famous to you that present ranges of atmospheric CO₂ are decrease than they’ve been for many of Earth’s historical past and that they had been dramatically larger tens of thousands and thousands of years in the past.

This is the kind of “talking point” that’s simply used to attenuate and dismiss present-day issues about local weather change, proper? Do you are worried that this noble concept of providing a “big picture” view of our present second within the context of Earth’s whole historical past can backfire?

So that alternate you talked about was largely about this time period known as the early Eocene, circa 50 million years in the past, when CO₂ was round 1,000 components per million within the ambiance, and Earth was about 12 levels Celsius hotter—and there was nonetheless a thriving biosphere.

But to assume that’s related for our scenario doesn’t present an appreciation or data of deep time—fairly the alternative.

Like, sure, 50 million years in the past, CO₂ was a lot larger than it’s at the moment, and there have been crocodiles and palm timber within the Arctic, and life was fairly completely satisfied. But when you ever so barely poke at that “argument,” it simply stops making sense as a result of, for the previous few million years, we have now lived on a planet that has been in a weirdly low atmospheric CO₂ regime—after an extended, lengthy decline in CO₂ and temperature from the “greenhouse” world left over from the age of the dinosaurs. And meaning many of the biosphere is now tailored to Earth being in an “icehouse” world that has ice ages. We’re technically nonetheless in an ice age, really, as a result of we nonetheless have polar ice caps. And we dwell on a planet that’s presently partitioned by nationwide borders and has greater than eight billion individuals depending on staple crops in sure particular locations the place climate and local weather enable. So okay, if we reverse these traits which have prevailed for tens of thousands and thousands of years and, in only a century or two, get atmospheric CO₂ ranges as excessive as they had been within the Eocene and out of the blue dwell in a world the place crocodiles could be comfy within the Arctic—when you assume our international civilization can stand up to that shock, properly, then you will have extra religion in humanity than I do.

There are precedents within the geological file for what’s occurring now—and taking a look at them is fairly terrifying. We simply settle for as regular that we have now an entire continent, Antarctica, that’s coated with kilometers-thick ice sheets. But that’s really fairly uncommon in Earth historical past. One of the opposite instances the world had comparable “icehouse” circumstances, resembling an ice-covered continent, after which out of the blue shifted to a greenhouse-style local weather was the Ordovician mass extinction. And that was 445 million years in the past, earlier than the planet even had timber. That’s an alien world!

Or have a look at how a lot and how briskly we’re injecting CO₂ into the carbon cycle, into the ambiance. The Permian mass extinction, the most important one we all know of—paleontologists name it the Great Dying—concerned large volcanic eruptions that pumped extra CO₂ into the air than we ever may even when we burned all out there fossil fuels. And that basically overwhelmed the carbon cycle and deranged Earth’s local weather in all types of terrible methods, and there was an enormous warming spike and virtually all the pieces died. You would possibly assume, nice, we will’t launch as a lot CO₂ as these eruptions did again then, even when we tried. But it’s not simply the quantity of CO2 launched; the fee issues loads. Those eruptions occurred over tens of hundreds of years. And proper now, so far as we all know, we’re emitting CO₂10 instances quicker than was emitted within the run-up to the Permian mass extinction. So what we’re doing proper now could be fairly geologically unprecedented; we actually are in uncharted territory. That doesn’t imply we’ll essentially spark one other mass extinction on par with the Permian, however we actually are leaping into the unknown.

This jogs my memory of one in every of my favourite quotes out of your guide: “Anyone who tells you they know what even four degrees of warming or more in a century will actually mean—or what that will look like on a planet gripped by ice ages for the past three million years—is full of shit. Especially if they’re an economist.”

I do ponder whether you’re personally extra optimistic or pessimistic right here—and the way you assume we’d ever get to a world the place we don’t burn any extra fossil fuels.

Believe it or not, I’m much less pessimistic now than I used to be once I began writing the guide in 2020; loads has modified previously 5 years. I’ve not too long ago began to raised recognize the superb factor that’s occurring now with solar energy. It’s actually getting astonishingly low-cost, and China and lots of growing international locations are prioritizing photo voltaic and issues resembling electrical vehicles over fossil fuels simply because it’s higher know-how. Solar doesn’t have as many terrible geopolitical implications as fossil fuels or nuclear power. There are nonetheless issues, resembling provide chains for rare-earth minerals, for instance. But, hey, the very fact is: there’s a nuclear reactor within the sky known as the solar that’s simply beaming out free power for us to make use of.

So you possibly can think about photo voltaic blowing away the fossil gas world in the identical approach that the fossil gas world blew away the world of horse-drawn carriages and plows—as a result of it was loads simpler to purchase low-cost fuel and fill your tractor—actually, to dig seas of oil out of the bottom and light-weight them on hearth—than it was for everybody to take care of stables of horses, proper? That could also be what occurs subsequent: photo voltaic will get cheaper and simpler and simply outcompetes fossil fuels in most domains.

But I don’t like this ethos that’s all too frequent, which is that you simply’re by no means supposed to provide individuals doom and gloom in regards to the local weather. I believe having the shit scared out of you isn’t all the time a nasty factor—as a result of, yeah, you possibly can have a look at graphs displaying the extraordinary progress in photo voltaic, and also you would possibly assume we’re simply on rails, and we’re inevitably transferring towards this new, higher world. But that’s most likely unsuitable—it’s going to take concerted political intervention to cease burning fossil fuels, which is what we’re going to need to do.

I’m glad you introduced up how a lot has modified previously 5 years by way of lower-carbon power and why there could also be causes for optimism. But, to be a little bit of a downer, what about issues such because the rise of AI and the related ramp-up in power utilization for information facilities and computation?

Or, since you talked about politics, how are you going to be optimistic, given the political scenario on this nation? It appears the ascendant view now on the highest ranges of our authorities is that local weather change isn’t actual—and whether it is actual, it’s not an issue—and if it’s an issue, it’s not one thing we will remedy, so we should always simply proceed with enterprise as ordinary. I imply, yikes!

It’s positively not my space of experience, however all these AI corporations are burning by means of billions of {dollars}, and so they’re not turning a revenue, and it doesn’t look like these instruments enhance productiveness that a lot in most domains. Although they’re profoundly helpful in some areas, resembling biotech, the place it looks like you should use them to do virtually a 12 months’s value of analysis in a day. And all of them appear to wave away the truth that you mainly have to construct nuclear reactors to energy this stuff, which isn’t going to be low-cost to do. The level is that I think about this can prove a bit just like the tech bubble of the 2000s: you’ll have some genuinely productive, game-changing functions, however many of the initiatives will go underneath as a result of you possibly can’t simply preserve dropping billions of {dollars} per quarter perpetually whereas additionally dealing with ever rising power calls for. It appears ripe for a large adjustment.

The U.S. can barely handle its present electrical grid, a lot much less fully rebuild it and add twice as a lot energy. Like so many different issues we do, sooner or later, the AI increase goes to run into constraints that collide with politics, economics or physics. So I’m skeptical there. Then once more, it’d be nice if we gained some power breakthrough out of necessity as a result of that’s normally once we determine stuff out. But I don’t assume one thing resembling fusion energy goes to occur anytime quickly, even with AI as a stimulus.

And as for politics, within the context of my guide, I discuss these successive hegemonic powers over the previous 500 years—which isn’t an concept I got here up with. But yeah, you will have the Dutch empire, after which the British empire after which the U.S. empire, every stepping up as the opposite will get senescent. And in that framework, taking a look at our political scenario, it’s onerous to keep away from the conclusion that regardless of its many superb benefits, the U.S. is someway previous its prime and has chosen to cede its international management. And the remainder of the world is now determining the right way to make do with out us. Maybe it’s simply the dying throes of a sure a part of our society, having a spasm and tearing all the pieces down whereas it nonetheless can. And possibly as soon as the fever breaks, as soon as we hit all-time low, there’ll be nowhere left to go however up. But I’m probably not optimistic about that, to be completely trustworthy.

Talking about empires—nation-state superpowers—iteratively shaping the entire world jogs my memory: As a journalist protecting “space,” I ought to notice some individuals would argue lots of the issues we’ve been discussing boil all the way down to being confined to 1 planet. The concept is that by someway making life multiplanetary and increasing our financial sphere out into the broader photo voltaic system, we may cut back our unfavourable impacts on Earth whereas additionally persevering with the constructive exponential progress traits we’ve seen in current centuries.

I’m wondering when you assume that there’s any validity to that pondering or that it’s all a naive, starry-eyed pipe dream.

I perceive the imaginative and prescient and the logic behind it, and I believe we want house exploration as a result of it’s necessary to grasp our place within the universe. But yeah, we’d need to do some surprising issues in house to proceed the exponential curve of the previous couple centuries that you simply talked about, resembling remodeling the whole photo voltaic system into a spot that’s of extra direct profit to our human—or posthuman, I don’t know—society and trade.

Some individuals appear to view the previous few centuries as kind of this new trajectory that’s going to go on perpetually. But if you recognize how unusual it’s and what it required—exploding this planetary battery —and the way we by no means actually see countless exponential progress in any advanced pure system, that appears unlikely. Things normally as an alternative show an S curve, which appears to be what we’re following now. In the guide, I quote this scientist who’s performed some back-of-the-envelope calculations displaying the ridiculous issues that should occur when you do take these exponential eventualities critically. If there’s a conservative relationship between power and financial progress, then inside 400 years, you’re both boiling off the oceans with waste warmth—which isn’t going to occur—otherwise you’re protecting the whole planet with photo voltaic panels, which isn’t going to occur, both. And when you lengthen that pattern one other 1,000 years or so into the longer term, you’d be utilizing extra power than the solar emits in all instructions—and that’s clearly by no means going to occur, both. So sooner or later the energy-growth relationship goes to alter.

I don’t actually know what the world seems like when that change occurs; I don’t assume anybody does. But it does recommend that, a technique or one other, in a number of centuries, human society goes to be organized very in another way—as a result of proper now, if progress falters even for a number of years, this has main societal penalties: depressions and recessions and civil unrest and useful resource wars, and so forth. I speak within the guide about how, a number of centuries in the past, this factor known as the Little Ice Age helped to knock out the agricultural foundations of a kind of feudal system in Europe and may need spurred issues such because the Thirty Years’ War and plenty of different horrific stuff. And that paved the way in which for capitalism and the trendy nation-state, and all these things that also constructions our world at the moment. The level is: not that way back society regarded very completely different, and searching forward about the identical period of time, you possibly can foresee it should most likely need to look very completely different once more.

Back to house: More broadly, rising up, I used to be a complete house nerd. I used to daydream about alien squid underneath the ice of Europa or about residing in a settlement on Mars. But the extra I’ve discovered as I’ve gone on this journey into geoscience, the extra I’ve come to understand what an absolute miracle Earth is. For higher or worse, I’ve grow to be more and more tired of what’s “out there” as a result of what we have now “right here” is so unusual and delightful, and the historical past of Earth is so contingent and weird. Why would we ever wish to go to Mars, you understand?! We have Earth proper right here!

In planetary time, it’s like we wakened as human beings simply yesterday, and all the pieces on this world is made virtually good for us someway. And lots of that ties again to, sure, this international carbon cycle that’s in steadiness simply so—in order that there’s a tiny little bit of CO₂ within the air to maintain us barely heat sufficient however not so little that we freeze and never a lot that it fries all the pieces. And sufficient carbon is locked away in rock that we have now oxygen to breathe. And the truth that we’re now trashing this unimaginable place and destabilizing this superb system so shortly is kind of humiliating, as a society, that we’ve been such dangerous stewards of the planet.

We talked earlier about deep time and the way in which our incapacity to correctly comprehend and combine it into our lives blinds us to what we’re actually doing to the planet. And this makes me surprise: How do you assume individuals ought to really feel, occupied with deep time and our place in it? More pointedly, having immersed your self in all this for 2 books now, how do you really feel? How has this journey modified you?

There could be concern in emotions of awe, in dealing with the chic. And I like dwelling in that disconcerting house the place you’re conscious of and involved with issues and forces and scales which might be a lot larger than you. It’s a pleasant reminder that you simply’re probably not the principle character, the star of the present.

I dwell in Massachusetts, the place a few of this geology is more durable to see, however once I exit West, and I’m taking a look at some rock face that captures tens of thousands and thousands of years of historical past, the place the surroundings switches from the underside of the ocean to a lagoon to a riverbed to a desert again to the underside of the ocean, it’s humbling in one of the simplest ways. It actually chips away at your ego. And it may be consoling, even; given how uncontrolled issues really feel at the moment and the way loopy you can also make your self refreshing your social media feed and maintaining with information, there’s one thing very peaceable in considering time at these gigantic scales. For me, realizing there’ve been so many chaotic and scary chapters in Earth historical past, it’s consoling to know that in one million years, all the pieces’s going to be high quality.

But even so, deep time doesn’t actually have any apparent, direct relevance to your day by day life. None of us get to dwell on geological timescales, and we will solely care in regards to the issues which might be in entrance of us. Your private relationships and the individuals you’re keen on—these actually are crucial issues. I’ve struggled with this, I’ll admit. When I used to be writing the primary guide, my mother died, and I used to be grappling with dropping her whereas I used to be additionally gaining this new, extra cosmic perspective about Earth and our place in it. I by no means absolutely reconciled how one’s private expertise ought to inform this deeper, larger view.

So I simply come again to the recognizing the great thing about this world all of us share. There’s magnificence in being a part of this lengthy pageant of life. I consider my mother, and I consider how there’ve been numerous moms and their youngsters that beloved one another in numerous methods, nice and small, all through Earth’s historical past. I consider how, at the moment, you possibly can see dinosaur trackways the place—let’s say 93,871,252 years in the past, throughout April—a dino mom and her baby danced collectively for a second on a sand flat. That’s actually lovely—all of the extra so if you consider all these moments that didn’t even make it into the fossil file. It’s a privilege to bear witness to that and to be a small a part of this far larger story.