Causes and consequences of environmental perturbations through the Phanerozoic

Study of past carbon cycle perturbation events is fundamental for assessing Earth’s climatic and ecological sensitivities, and our planet’s overall biogeochemical functioning and responses. Major hindrance to our understanding is the lack of reliable CO₂ estimates from Earth’s ‘deeper’ geologic past. I will summarize my work on CO₂ reconstruction from the rock record and make the case that boron isotope values of brachiopod shells serve as a robust CO₂ proxy. I will first present evidence from culturing experiments and natural marine settings demonstrating that the boron isotope composition of recent brachiopod shells responds predictably to the coupled ocean pH and CO₂ system, and provide a calibration that enables its accurate quantification. Next, I will showcase ocean pH and CO₂ records for some of most crucial yet enigmatic events in Earth’s evolutionary history, including the Permian-Triassic mass extinction, and discuss the causes and consequences of CO₂ change and its biogeochemical impacts during extinctions and events of abrupt environmental change. Finally, I will highlight recent progress and new capabilities to lay out a roadmap towards robust record of Phanerozoic CO₂.