Life and CO2 in the Palaeozoic

The Palaeozoic Era saw profound transformation of our planet, marked by a rapid expansion of life in the oceans and on land, culminating in complex ecosystems before their abrupt disappearance in the greatest mass extinction. It offers a unique window into an ancient world, and the conditions that shaped life on Earth, and in turn, how life shaped its surface as it expanded across it. The rise and fall of biota during the Palaeozoic is thought to have been linked to global changes in the carbon cycle and climate. Recent advances in geochemical proxy application and computational modelling now enable robust reconstruction of CO2 from the geological record, providing new constraints on the evolution of the carbon cycle and climate during the Palaeozoic. Here, I review the role of CO2 in major events and mass extinctions of the Palaeozoic, and present an emerging view of the co-evolution of the carbon cycle, climate, and life during Earth’s “First Era”.