Towards a 500 Million-Year History of Earth’s Atmospheric CO2

Hana Jurikova, University of St Andrews Cambridge Fluids Network - fluids-related seminars 28 May 2024 12:00pm Department of Earth Sciences, Tilley Lecture Theatre Earth’s atmospheric CO2 concentration for the Phanerozoic Eon (the last ~540 million years) has been estimated from proxies and models with varying degrees of success, resulting in considerable discrepancies between estimates. Recent advances in applying boron isotopes to foraminifera have revolutionised our understanding of Cenozoic CO2 levels (the last ~66 million years) leading to a growing consensus for Earth’s more recent history. However, questions remain about the limitations of the boron isotope proxy as dependent on the extent of preservation of marine sediments and, consequently, deep-time boron-based reconstructions from Earth's rock record have been regarded as controversial. In this talk, I will make the case that the boron isotope composition of well-preserved brachiopod shells provides a robust tool for extending our knowledge of CO2 throughout the Phanerozoic, and by showcasing new Mesozoic and Palaeozoic records I will review the role of CO2 in Earth's major climate transitions and mass extinction events.