Elucidating Long-term Cretaceous Atmospheric pCO2 and Climate Sensitivity
This project will involve analysis of the boron isotope composition of fossil foraminifera and radiolarians to reconstruct ocean pH and atmospheric CO2 through the last 40 million years of the Cretaceous. This period includes some of the hottest temperatures of the Phanerozoic, and as such, is increasingly seen as an important period to study, as some IPCC scenarios would see CO2 levels in the next century that is potentially higher than at any point in the last 70 million years. At the moment, CO2 proxy records for this time are sparse, uncertain, and often disagree with one another. As applied to marine microfossils, the boron isotope–pH proxy is increasingly seen as an accurate and precise proxy for reconstructing CO2. Still, as yet, the oldest application of the proxy is around the end-Cretaceous mass extinction, and so the time is ripe to extend our boron-based estimates further back into the Cretaceous. This PhD project will be at the vanguard of these efforts, providing crucial new constraints on climate sensitivity to CO2. Trace element measurements made alongside these boron isotope measurements will also allow us to reconstruct ocean temperature and major ion chemistry at this time. This work will use International Ocean Discovery Program (IODP) marine drill core samples from around the Earth’s oceans. It will avail of the state-of-the-art analytical facilities housed within the Bristol Isotope Group (BIG) lab and dedicated sediment washing and micropalaeontology labs.
Deadline: February 15th 2023