The Story of CO2 Is the Story of Everything: How Carbon Dioxide Made Our World

Peter Brannen. The Story of CO₂ Is the Story of Everything: How Carbon Dioxide Made Our World. New York: HarperCollins, 2025. Pp 495. Illustrations, bibliography, index. Cloth, $35.

For the past quarter century, the world’s concerned citizens have primarily understood carbon dioxide, the product of the combustion of fossil fuels, to be the main greenhouse gas that is causing climate change.  They have urged that we curtail carbon dioxide if we are to preserve Earth as a planet suitable for human habitation and supportive of the other plant and animal species we call “Creation.”  Peter Brannen’s The Story of CO₂ Is the Story of Everything: How Carbon Dioxide Made Our World puts carbon dioxide in the much larger context of the deep history of our planet, showing the crucial role CO₂ has played over billions of years, long before life arose on Earth, to shape the oceans, Earth’s crust, and its atmosphere, as our planet has vacillated between the extremes of snowball Earth and a hothouse Earth, sometimes exceedingly gradually and sometimes rather suddenly (in geological time).  The purpose of Brannen’s deep history is twofold: to show that the conditions that lie ahead for our planet and its life forms are part of a long history of a dynamic planet, and to show that the past offers analogs to the future we are creating, and that from those analogs we can see how catastrophic our trajectory is likely to be for life on Earth.

Brannen is a journalist and science writer.  His previous book, The Ends of the World, describes the major mass extinctions that have occurred during our planet’s history.  Many of us may be familiar with the most recent one, 66 million years ago, when a meteor struck Earth at Mexico’s Yucatan Peninsula disrupting conditions on Earth so that the age of the dinosaurs ended.  The previous mass extinctions, however, were not caused by an object from space striking and upsetting conditions here but rather by the natural dynamism of our planet, with its molten core, shifting crust, and changing oceans and atmosphere.  Carbon dioxide played a role in those changes long before humans started burning fossil fuels; carbon dioxide was also central to the huge swings in conditions that Earth went through in the billions of years before life began on the planet.  Since that time, life forms (because CO₂ is central to life) have interacted with geological change to alter Earth, but long before life began on our planet, CO₂ was interacting with Earth’s crust and the oceans to drive change on the planet.  Carbon dioxide is more that the product of our burning of fossil fuels.  It is more than the gas in the atmosphere that plants use in photosynthesis to convert energy from the sun into stored chemical energy, and it is more than the gas that plants and animals exhale when they metabolize that chemical energy.  Carbon dioxide has been at the center of Earth’s dynamics almost from the beginning, hence the title of Brannen’s book.

The origin of the fossil fuels now buried in Earth’s crust was the Carboniferous period, about 300 million years ago.  That was a period when plants (including giant trees) and animals (including giant insects) lived on Earth’s surface.  Atmospheric temperatures and oxygen content were both very high.  Plants grew and died so fast in those conditions that each subsequent generation of plants died before the previous generation had decomposed, as happens naturally on current Earth. As a consequence, huge thicknesses of biomass developed, much of which lasted long enough to be buried in silt and eventually subsumed into the crust by geological processes.  They become what humans now call fossil fuels.  That geological process took vast abouts of carbon out of the carbon cycle and put it in storage.

The Carboniferous had several unusual features.  Atmospheric oxygen was so high (about 35%, compared to about 21% for current Earth), that huge insects lived then, including dragonflies the size of seagulls.  Insects don’t have lungs and circulate blood to supply oxygen and carry CO₂ away; rather, they have little passageways to supply air to their bodily tissues.  Huge insects could not survive in our atmosphere, because enough oxygen would not get to their tissues, but the atmosphere in the Carboniferous was so rich in oxygen that insects could grow to immense sizes.  Also, with so much oxygen in the atmosphere, fires could burn living plant matter, not just dead and dried biomass.  Conflagrations during the Carboniferous were so huge that they didn’t burn all the biomass, leaving large deposits of charcoal, which also was subsumed into the crust, leaving behind deposits of petrified carbon.

Earth’s carbon cycle is an important part of Brannen’s narrative.  Before there was life, carbon dioxide and rain would react chemically with the minerals comprising Earth’s surface in a process called weathering, washing new kinds of chemicals into the oceans, changing the chemical composition of the oceans, and causing new kinds of minerals to settle to the ocean floor.  Life forms added new dimensions to the carbon cycle through photosynthesis and metabolism, which take carbon dioxide out of the atmosphere and then return it.  Also, before there was life, there was no fire on Earth.  Both fuel and oxygen were lacking.  Fire, mostly caused by lightening, also became part of the carbon cycle.

Early in The Story of CO₂, Brannen recounts the story of the eighteenth-century French scientist who conducted an experiment to demonstrate that, in terms of the chemical end result, combustion and metabolism are identical: fuel and oxygen yield energy and CO₂.  That equivalence is a driving factor in the second half of The Story of CO₂.  For all of mammalian history, mammals got all the energy they needed to survive by eating plants or other animals that had eaten plants.  Quite recently, in geological time, humans came along, also dependent on eating and metabolizing plants and animals to supply the energy needed to live.  At some point, however, humans learned how to harness fire, which enabled cooking food.  Cooking means it takes less energy for our gut to digest food (remember that everything our bodies do requires energy, and that includes digestion).  In other words, humans used fire outside their bodies to do some of the work necessary to metabolize food.  And that, in turn, allowed human bodies to evolve to different proportions than other mammals.  The human gut is considerably smaller than that of other mammals, and the human brain is much larger.  The human brain comprises only about 2% of body mass, but it consumes about 20% of the energy a human body uses.  Cooking made those proportions of the human body possible.

Over the millennia, humans devised other means of having energy transformations occur outside the human body to enhance what the body could do, including developing agriculture, domesticating animals, and harnessing wind and water power.  In time, humans developed into something we call civilization, which Brannen says is based on two institutions: technology and bureaucracy.  Civilization, he says, has allowed societies and empires to use the energy from photosynthesis, not to accomplish the same amount with less energy, but to do more things with more energy (p. 288).  One consequence is that we have greatly increased Earth’s carrying capacity for humans.  Indeed, two thirds of the solar energy put into storage as chemical energy by photosynthesis now flows through human societies.   Through all those changes in the ways humans derived their livelihoods from Earth, however, one thing remained the same: the ultimate source of all the energy humans used—whether for metabolism or cooking and heating, or mechanical power—was the solar energy that struck Earth’s surface and atmosphere.  The situation changed when humans learned to use the solar energy put into storage from the Carboniferous, i.e., learned to use fossil fuels.

Humans had been using fossil fuels on a very small scale for thousands of years, but about 250 years ago, people in England figured out how to burn coal to make steam and generate mechanical power, first to pump water from coal mines but quickly to do lots of other things.  That ability spread to the rest of the world.  The twenty-first century is a result of the rapid pace in technological innovation that has occurred since the Industrial Revolution, coupled with new forms of social and political organization and the management of human organizations.  Those changes have allowed a sudden burst in human population and also the transfer of vast stores of carbon from the Carboniferous back into the atmosphere.  Those actions are triggering reactions in Earth’s geological dynamics at a rate unseen in Earth’s history (other than when a meteor struck).  Brannen’s book allows us to see the geological scope of what we are doing.  He calls it a supereruption of carbon dioxide.  And our current trajectory is toward another (in geological terms) cataclysmic change in Earth’s conditions that will be uninhabitable by humans and many other living things.

In the closing chapter of The Story of CO₂, “The Future of CO₂,” Brannen reminds the reader of something he had mentioned earlier in the book: about 3 billion years ago, “life evolved a mineral structure anchored by four manganese atoms—an arrangement found in no rock on Earth, or in the solar system for that matter” (p 418).  Plants and certain bacteria use that mineral structure to accomplish photosynthesis, taking solar energy to break apart water molecules and use carbon dioxide from the atmosphere to make plant tissue, i.e., stored chemical energy.  This process, he writes, “was invented, brought into being, by biology.  We still don’t quite understand how photosynthesis works or how it evolved” (p 419).  Elsewhere in the book, he calls this miraculous.  (People of faith might attribute that miracle to God, but nowhere in The Story of CO₂ does Brannen attribute any of the miracles he describes to God.)

Brannen reminds of us of this strange fact involving manganese to introduce other key uses to which life puts minute amounts of various metals, like iron, molybdenum, and vanadium, in the cells of organisms to perform important functions.  He then uses this thought to address the importance of metals to civilization and to a path forward that is eventually free of fossil fuels.  He pays particular attention to copper, needed to move energy (electricity, produced from renewable sources) around, in lieu of using fossil fuels to transport energy.  Mining and smelting copper has caused more adverse environmental impacts than most other metals, but Brannen asserts that if we are to convert to an economy free of burning fossil fuels, we are going to have to mine more copper than we are mining now, and quickly.  He writes that we have to choose between two dire alternatives: 1) we can increase the production of copper in order to develop a carbon-free energy system, knowing that it will cause many negative environmental impacts, or 2) we can choose not to build out the infrastructure for an economy based on renewable energy sources, a choice that will entail business as usual, pumping vast amounts of carbon dioxide into the atmosphere and hastening the rise in temperatures by 5 degrees C or more and ending current Earth, which sustains human beings and many other forms of life.

Brannen is also adamant that choosing the former alternative will not happen by letting the market decide.  The decision will have to be made by governments, and he uses a grim example to demonstrate.  In the mid-nineteenth century, the textile industry in England believed that the market for cotton, produced by enslaved human begins in the American South, looked secure for the foreseeable future.  The end of slavery in the United States came not by market forces but by a Civil War the killed more than 600,000 people.  Near the end of the book, Brannen concludes, “For better or worse, I think there’s no way out but through.  We have to find a way to somehow thread the needle between supplying enough energy to vastly expand the human project such that it can flourish, and do so without destroying the world.” (p 429).

The Story of CO₂ is an excellent book on several fronts.  It is a fascinating overview of the deep geological history of our planet, and it narrates a history of how our species evolved to become a formidable actor in that geological history.  Finally, it presents a compelling argument for the necessity of humanity’s making a serious course correction, and soon.

Fredric L. Quivik