Palaeoclimate change and the Carbon Cycle

The Earth’s climate has changed ever since the Earth formed, but the drivers of these changes are not clear. If solar luminosity drove climate change alone then the Earth would have started out much chillier than evidence suggests and gradually heated throughout its history – a pattern at complete odds with geological records. The effect of changing concentrations of greenhouse gases is a more likely driver, but the drivers of these changes through time are not fully understood. In my PhD and a follow-up Post-Doc project I studied the potential drivers and dynamics of some of the major perturbations to the carbon-climate system during the Cenozoic:

PhD: ‘What were the drivers of carbon-climate system perturbations during the Cenozoic?’ (2011-2015)

Over the course of the Cenozoic (the last 66 million years) the Earth system has shifted from a CO2-rich ‘Greenhouse’ climate state to a CO2-poor ‘Icehouse’ climate state. This trend is punctuated by numerous perturbations to the carbon-climate system, but the extent of the coupling between the carbon cycle and climate system, the drivers of these perturbations, and their relationship to the longer-term Cenozoic trend is still debated.

In my PhD thesis I used biogeochemical modelling and numerical analysis to explore the key research question: ‘What were the drivers of carbon-climate system perturbations during the Cenozoic?’, with a focus on perturbations during the Eocene-Oligocene Transition and the mid-Miocene, the role of tipping points during these periods, and the long-term evolution of the ocean carbonate system.

So far I have published 2 papers from my PhD (see my writing page for details and links) on the impact of the Columbia River Basalt large igneous province eruptions on the carbon-climate system in the mid-Miocene (around 16 million years ago) and the drivers of the carbon cycle perturbation during the glaciation of Antarctica in the Eocene-Oligocene Transition (~34 million years ago). I also co-authored a paper on the likely extent of ocean acidification as a result of the dinosaur-killing asteroid impact at the Creataceous-Palaeogene boundary (~66 Ma) and the role of Methane Hydrate dissociation during the infamous Palaeocene-Eocene Thermal Maximum (PETM, ~55 Ma), and am currently preparing further papers from my Thesis.

Post-Doc 1.2: Can early warning signals be reliably detected in the Cenozoic palaeoclimate record? (2016)

In the summer of 2016 I received funding from the EPSRC/ReCoVER network for a 3 month Post-Doctoral Research Fellow position at the University of Southampton, which follows on from my tipping point / early warning research in my PhD. You can find more information on the Resilience, Tipping Points, & Early Warnings page.

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