Reconstructing earth's ancient carbon cycle

The fixation of atmospheric CO2 into organic matter, through the activity of primary producers, has been the most important bridge between the inorganic and organic carbon cycles over Earth history and a key control on the planet’s surface oxidation state and climate. Therefore, central to understanding Earth’s past is constraining the ancient carbon cycle. While the sedimentary record has revealed a large wealth of information, interpreting well-developed records such as carbon isotopes in shallow marine carbonates poses a large challenge due to local environmental factors as well as diagenetic processes. These challenges require that new approaches to probe key aspects of Earth’s ancient carbon cycle are developed and applied. In this talk I will provide an overview of work that has sought to constrain primary productivity across the history of the Earth. I will highlight some ongoing challenges as well as some key insights that can be drawn from these exciting new geochemical records. For example, what is the most abundant group of organisms to have ever existed? And how many cells has there ever been on Earth? I will finish by briefly highlighting research which aims to link ancient organic carbon burial and primary productivity through a new proxy for ancient carbon export.