During my PhD, I worked on developing and validating new methods for reconstructing past PCO2 by using environmental proxies. Specifically, I explored the stable carbon isotopic fractionation associated with CO2-fixation in photoautotrophs. Fractionation is usually calculated from the species-limited alkenone compounds, produced starting ca. 50 million years ago. I’ve expanded this concept to general phytoplankton biomarkers, compounds that are produced by a multitude of species, in order to provide a more spatially and temporally ubiquitous record. I then applied these general biomarkers to different environments and timescales. Here, I will show the culmination of this work, ranging from modern CO2 vents to 500 million year timespans.

Caitlyn Witkowski, PhD student at NIOZ Texel under supervision of Stefan Schouten and Jaap Sinninghe Damsté, is working on development of a novel proxy for past PCO2. She will soon start a post-doctoral position at the University of Bristol in the Organic Geochemistry Unit.