By Madeleine Mulligan (A&S ‘27)
In an era where carbon dioxide (CO2) is a dirty word, blamed for warming global temperatures and sea level rise, Peter Brannen hopes to reframe the CO2 narrative.
In his newest book, The Story of CO2 Is the Story of Everything: How Carbon Dioxide Made Our World (Ecco, 2025), Brannen ('08) reintroduces the reader to CO2, reminding them of its true importance. In studying the planet’s history through the lens of CO2, Brannen was able to see that it’s even responsible for the Earth’s greatest miracle: life.
“I realized that there's a much bigger story to be told about CO2 than the one that you hear about in the news,” he said.
Tracing the earth’s history from the beginning of life to the current climate crisis, The Story of CO2 Is the Story of Everything demonstrates how CO2 has been fundamental to the planet’s every function. Through field research in places like Death Valley, Brannen tracks CO2’s role in everything from evolution to modern society.
Brannen argues that the carbon cycle is vital for understanding not just the earth’s past, but how it can be preserved in the future. There are still very open questions about CO2, he writes, and they are not restricted to climate change.
“The book's not all about climate gloom and doom. It also is about how it's transformed life over its history,” Brannen said.
While he wants the reader to realize the gravity of the current climate situation, Brannen hopes that they can also come away with similar appreciation to what he gained in writing the book. Life, according to Brannen, is ultimately a miracle when considering the complex cellular nanochemistry that allows the earth to be habitable.
“There's the scary stuff about climate, but I also just came away from this whole experience feeling a sense of cosmic gratitude,” he said.
Brannen began his career working for small papers and pitching environmental stories to his editors when he could. Now a contributor to The Atlantic, he took an interest in geology in the past decade, which led him to write his first book, The Ends of the World.
Detailing the five major mass extinctions in earth’s history, the book describes how the four events before the one that wiped out the dinosaurs were not due to asteroids. Instead, they all involved climate events that have much in common with what is being done to the planet today.
“I was just motivated to learn the science because I, for whatever reason, latched onto it and really obsessed with it,” Brannen said.
Now, having published his second book, Brannen has become well-accustomed to the intensive research and field work required. But The Story of CO2 Is the Story of Everything was far from an easy writing process. It required more research than Brannen’s first book and was partially written during the pandemic, when many field projects were put on hold.
Still, Brannen had a story to tell—one that he knew was necessary for paving humanity’s way forward.
“I think unless you kind of grapple with how important this stuff is over all of earth history," he said, "it's hard to appreciate just how radical it is what we're doing to the planet."