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, yes, practically everything under the sun—from the primordial origins of life to the development of human civilization and our global economic system. From the ancient past to the present day, Brannen makes the case that to understand CO2 is to understand the very fabric of our world.