A New View of CO2

The most important and most misunderstood molecule on Earth

- BY LEE BILLINGS

WHEN WE TALK ABOUT CARBON DIOXIDE, the narrative is almost always that of a modern-day morality play. We hear about gigatons of CO₂ emitted, about rising global temperatures and about the dire, unheeded warnings of climate scientists. In these tales, CO₂ often seems less like a mute, inert molecule and more like a supervillain—a malevolent force that has been plotting for centuries to wreak havoc on our planet and ruin our lives.

But according to science journalist Peter Brannen, that dismal view is far too narrow. In his latest book, The Story of CO₂ Is the Story of Everything (Ecco, 2025), he reframes our understanding of what may be the most vilified and misunderstood molecule on Earth.

Inspired and informed by conversations with leading planetary scientists, Brannen's central argument is that CO₂ is not merely an industrial pollutant but a key player in the four-billion-year-old drama of life on Earth. It is the molecule that built our planet, forming the global carbon cycle that has regulated climate, shaped geology and powered evolution for eons. He shows how the ebb and flow of atmospheric CO₂ across Earth's vast history has played a role in practically everything under the sun—from the primordial origins of life to the development of human civilization and our global economic system. Brannen makes the case that to understand CO₂, from the ancient past to the present day, is to understand the very fabric of our world.

SCIENTIFIC AMERICAN spoke with Brannen about what's in his new book, how he came to see a simple gas as a character in a planetary epic, and what the long history of CO₂ can tell us about our precarious present moment—and our uncertain future.

An edited transcript of the interview follows.

How did this book come to be?

That's always a great way to start. My previous book,