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 power that has been plotting for hundreds of years to wreak havoc on our planet and smash our lives.

But in accordance with science journalist Peter Brannen, that dismal view is much too slim. In his first e-book, The Ends of the World, Brannen chronicled Earth’s five major 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 way 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 is just not 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 stream of atmospheric CO₂ throughout Earth’s huge historical past has performed a job in, sure, virtually all the things below 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 know CO₂ is to know the very cloth of our world.

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Scientific American spoke with Brannen about what’s in his new e-book, how he got here to see a easy gasoline 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 e-book come to be? That’s all the time an effective way to start out.

My earlier e-book, The Ends of the World, was in regards to the 5 largest mass extinctions identified 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 latest 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 report, are most related to main biogeochemical occasions, normally involving huge 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 present.

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

But in the midst of researching that e-book, I noticed—I’m not the primary to suppose 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 akin to methylmercury or chlorofluorocarbons, and so forth. It’s essentially totally 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 abruptly injected into the environment, this causes unhealthy occasions, however in “normal” instances, because it strikes by way of the biosphere and between the air, the rocks and the ocean—the so-called international carbon cycle—CO₂ is actually 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 a different way there in the way it cycles across the planet; it’s constructed up a lot in Venus’s environment that it’s prompted a runaway greenhouse impact, which is why Venus is a hell world whereas Earth is relatively an awesome place to stay, proper subsequent door. Or, , if all of the CO₂ in our environment abruptly vanished, temperatures would quickly plunge and earlier than too lengthy, glaciers would unfold right 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, the truth is—that there’s CO₂ in Earth’s air, however we are able to 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 very important position in shaping life on Earth.

I 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 concerning planetary habitability and the actual fact of Earth’s carbon-based life. It’s tougher, I feel, to understand and convey how people come into the story, and one factor I like about your e-book 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 taking place now with local weather change, it’s essential to perceive this international carbon cycle I discussed; life is etched within the stream of carbon throughout our planet. And what I attempt to do in later components of the e-book is describe how all of human historical past could be seen by way of this lens—so societies and empires, as an illustration, are composed of flows of carbon being organized in numerous methods. And the best way our society and politics have developed throughout the previous few centuries, it seems, is carefully linked with issues akin to 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 power on the planet—and the way weird and essential this second in Earth historical past actually could be.

What’s so extraordinary about our present second is how one species on one department of this gigantic tree of life has abruptly found this huge, historical underground reservoir of carbon made by outdated 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 vitality—is de facto the identical factor that every one cardio life, all of Earth’s animals and vegetation, and so forth, makes use of to drive its metabolism on a mobile stage. We’re simply doing this nightmarish, freakish model of it, the place we’re abruptly combusting all of life’s leftover carbon from Earth’s historical past below our toes. 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 e-book about chemistry, however I want so as to add that the one means this all works at any scale is having a number of free oxygen within the environment to react with the carbon. The air we breathe at present 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 almost 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 just a few billion years in the past. You additionally must continuously 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 lot of hundreds of thousands of years; in any other case the 2 react collectively, which pulls oxygen again down. But should you lock that carbon up within the crust, oxygen will rise. Now, outdated plant stuff locked up within the crust, in these pockets the place it’s economically exploitable, is healthier referred to as fossil gas, proper? I wager lots of people don’t know that the rationale why they’ll breathe is as a result of there are fossil fuels below their toes.

I like to think about this interaction between carbon within the floor and oxygen within the air as making an enormous planetary-scale battery, the place you get two components of Earth—the actually reactive, oxidizing environment and the actually lowered natural matter underground—out of equilibrium with one another, with a number of potential vitality consequently. Then this bizarre hearth creature abruptly 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 vitality. 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 right down to our getting higher and higher at discharging Earth’s battery, dissipating all of the potential vitality throughout this barrier.

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

But I need to watch out: When you discuss it this fashion, it may well seem to be what we’re doing is simply this inevitable, pure course of, and I don’t suppose 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 present is extraordinarily unnatural in some methods, however I simply discover it eerie that it resembles this larger image: All life finds and dissipates free vitality 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 largest supply of free vitality ever to exist on Earth.

What do you suppose 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 means out? Easy questions, I do know.

What Earth historical past tells us is that burning fossil fuels is just not 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 may well’t final eternally. So if we’re going to endure into the geological future, we have to in a short time discover one other supply of vitality at an equal scale to energy society.

I feel possibly the encouraging factor is that the general public dialog, for many of the world, isn’t about debating the elemental science anymore. The science is settled. It’s about totally different questions—of understanding the complexity and interconnectivity of the worldwide carbon cycle and our place in it or of political financial system and understanding 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 know people as a part of those pure techniques. This is why I feel learning and speaking about local weather change is probably the most interdisciplinary factor you are able to do as a result of you’ll be able to’t actually divide these thorny problems with how we should always set up 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 prefer to suppose my half, the worthwhile service I can present with my storytelling, is to raised illustrate simply how huge 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 quite a lot 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 e-book 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 have been dramatically larger tens of hundreds of thousands of years in the past.

This is the kind of “talking point” that’s simply used to reduce and dismiss present-day considerations 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 trade 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 environment, and Earth was about 12 levels Celsius hotter—and there was nonetheless a thriving biosphere.

But to suppose that’s related for our state of affairs doesn’t present an appreciation or information of deep time—fairly the other.

Like, sure, 50 million years in the past, CO₂ was a lot larger than it’s at present, and there have been crocodiles and palm bushes within the Arctic, and life was fairly completely satisfied. But should you ever so barely poke at that “argument,” it simply stops making sense as a result of, for the previous few million years, we’ve got 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, truly, as a result of we nonetheless have polar ice caps. And we stay 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 permit. So okay, if we reverse these traits which have prevailed for tens of hundreds of thousands of years and, in only a century or two, get atmospheric CO₂ ranges as excessive as they have been within the Eocene and abruptly stay in a world the place crocodiles could be snug within the Arctic—should you suppose our international civilization can stand up to that shock, properly, then you may have extra religion in humanity than I do.

There are precedents within the geological report for what’s taking place now—and taking a look at them is fairly terrifying. We simply settle for as regular that we’ve got a complete continent, Antarctica, that’s lined with kilometers-thick ice sheets. But that’s truly fairly uncommon in Earth historical past. One of the opposite instances the world had comparable “icehouse” circumstances, akin to an ice-covered continent, after which abruptly 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 bushes. 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 environment. The Permian mass extinction, the largest one we all know of—paleontologists name it the Great Dying—concerned huge volcanic eruptions that pumped extra CO₂ into the air than we ever might even when we burned all accessible 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 things died. You would possibly suppose, nice, we are able to’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 price issues loads. Those eruptions occurred over tens of 1000’s of years. And proper now, so far as we all know, we’re emitting CO₂10 instances sooner 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 considered one of my favourite quotes out of your e-book: “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 suppose 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 e-book in 2020; loads has modified prior to now 5 years. I’ve not too long ago began to raised admire the superb factor that’s taking place now with solar energy. It’s actually getting astonishingly low cost, and China and plenty of growing nations are prioritizing photo voltaic and issues akin to electrical automobiles over fossil fuels simply because it’s higher expertise. Solar doesn’t have as many terrible geopolitical implications as fossil fuels or nuclear vitality. There are nonetheless issues, akin to provide chains for rare-earth minerals, for instance. But, hey, the actual fact is: there’s a nuclear reactor within the sky known as the solar that’s simply beaming out free vitality for us to make use of.

So you’ll be able to think about photo voltaic blowing away the fossil gas world in the identical means 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 gasoline and fill your tractor—actually, to dig seas of oil out of the bottom and lightweight 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 widespread, which is that you simply’re by no means supposed to provide individuals doom and gloom in regards to the local weather. I feel having the shit scared out of you isn’t all the time a foul factor—as a result of, yeah, you’ll be able to have a look at graphs displaying the extraordinary progress in photo voltaic, and also you would possibly suppose we’re simply on rails, and we’re inevitably transferring towards this new, higher world. But that’s most likely flawed—it’s going to take concerted political intervention to cease burning fossil fuels, which is what we’re going to must do.

I’m glad you introduced up how a lot has modified prior to now 5 years by way of lower-carbon vitality 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 vitality utilization for information facilities and computation?

Or, since you talked about politics, how will you be optimistic, given the political state of affairs 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 are able to remedy, so we should always simply proceed with enterprise as traditional. I imply, yikes!

It’s positively not my space of experience, however all these AI corporations are burning by way of billions of {dollars}, they usually’re not turning a revenue, and it doesn’t seem to be these instruments improve productiveness that a lot in most domains. Although they’re profoundly helpful in some areas, akin to biotech, the place it looks as if you should utilize them to do virtually a yr’s value of analysis in a day. And all of them appear to wave away the truth that you mainly must construct nuclear reactors to energy these items, which isn’t going to be low cost to do. The level is that I think about this may 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 below as a result of you’ll be able to’t simply hold shedding billions of {dollars} per quarter eternally whereas additionally going through ever growing vitality calls for. It appears ripe for an enormous adjustment.

The U.S. can barely handle its present electrical grid, a lot much less utterly rebuild it and add twice as a lot energy. Like so many different issues we do, in some unspecified time in the future, 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 vitality breakthrough out of necessity as a result of that’s normally after we determine stuff out. But I don’t suppose one thing akin to fusion energy goes to occur anytime quickly, even with AI as a stimulus.

And as for politics, within the context of my e-book, I discuss these successive hegemonic powers over the previous 500 years—which isn’t an concept I got here up with. But yeah, you may 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 state of affairs, it’s laborious to keep away from the conclusion that regardless of its many superb benefits, the U.S. is by some means 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 things 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 overlaying “space,” I ought to observe some individuals would argue most of the issues we’ve been discussing boil right down to being confined to 1 planet. The concept is that by by some means making life multiplanetary and increasing our financial sphere out into the broader photo voltaic system, we might scale back our unfavourable impacts on Earth whereas additionally persevering with the optimistic exponential progress traits we’ve seen in latest centuries.

I’m wondering should you suppose that there’s any validity to that considering or that it’s all a naive, starry-eyed pipe dream.

I perceive the imaginative and prescient and the logic behind it, and I feel we’d like area exploration as a result of it’s essential to know our place within the universe. But yeah, we’d must do some surprising issues in area to proceed the exponential curve of the previous couple centuries that you simply talked about, akin to reworking all the photo voltaic system into a spot that’s of extra direct profit to our human—or posthuman, I don’t know—society and business.

Some individuals appear to view the previous few centuries as kind of this new trajectory that’s going to go on eternally. But while you admire how unusual it’s and what it required—exploding this planetary battery —and the way we by no means actually see limitless exponential progress in any complicated pure system, that appears unlikely. Things normally as a substitute show an S curve, which appears to be what we’re following now. In the e-book, I quote this scientist who’s achieved some back-of-the-envelope calculations displaying the ridiculous issues that should occur should you do take these exponential situations significantly. If there’s a conservative relationship between vitality 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 overlaying all the planet with photo voltaic panels, which isn’t going to occur, both. And should you prolong that development one other 1,000 years or so into the longer term, you’d be utilizing extra vitality than the solar emits in all instructions—and that’s clearly by no means going to occur, both. So in some unspecified time in the future the energy-growth relationship goes to vary.

I don’t actually know what the world seems like when that change occurs; I don’t suppose anybody does. But it does recommend that, a technique or one other, in just a few centuries, human society goes to be organized very in a different way—as a result of proper now, if progress falters even for just a few years, this has main societal penalties: depressions and recessions and civil unrest and useful resource wars, and so forth. I speak within the e-book about how, just a few 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 might need spurred issues such because the Thirty Years’ War and plenty of different horrific stuff. And that paved the best way for capitalism and the trendy nation-state, and all these things that also buildings our world at present. The level is: not that way back society seemed very totally different, and searching forward about the identical period of time, you’ll be able to foresee it’ll most likely must look very totally different once more.

Back to area: More broadly, rising up, I used to be a complete area nerd. I used to daydream about alien squid below the ice of Europa or about dwelling 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 turn out to be more and more tired of what’s “out there” as a result of what we’ve got “right here” is so unusual and delightful, and the historical past of Earth is so contingent and weird. Why would we ever need to go to Mars, ?! We have Earth proper right here!

In planetary time, it’s like we awoke as human beings simply yesterday, and all the things on this world is made virtually excellent for us by some means. And quite a lot of that ties again to, sure, this international carbon cycle that’s in stability 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 things. And sufficient carbon is locked away in rock that we’ve got oxygen to breathe. And the truth that we’re now trashing this unbelievable place and destabilizing this superb system so rapidly is kind of humiliating, as a society, that we’ve been such unhealthy stewards of the planet.

We talked earlier about deep time and the best way our incapability to correctly comprehend and combine it into our lives blinds us to what we’re actually doing to the planet. And this makes me marvel: How do you suppose individuals ought to really feel, eager about 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 going through the elegant. And I like dwelling in that disconcerting area the place you’re conscious of and in touch with issues and forces and scales which are 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 stay in Massachusetts, the place a few of this geology is tougher to see, however once I exit West, and I’m taking a look at some rock face that captures tens of hundreds of 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 best ways. It actually chips away at your ego. And it may be consoling, even; given how uncontrolled issues really feel at present 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, understanding there’ve been so many chaotic and scary chapters in Earth historical past, it’s consoling to know that in 1,000,000 years, all the things’s going to be superb.

But even so, deep time doesn’t actually have any apparent, direct relevance to your day by day life. None of us get to stay on geological timescales, and we are able to solely care in regards to the issues which are in entrance of us. Your private relationships and the individuals you like—these actually are crucial issues. I’ve struggled with this, I’ll admit. When I used to be writing the primary e-book, my mother died, and I used to be grappling with shedding 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 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 liked one another in numerous methods, nice and small, all through Earth’s historical past. I consider how, at present, you’ll be able to 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 while you consider all these moments that didn’t even make it into the fossil report. It’s a privilege to bear witness to that and to be a small a part of this far higher story.