PhD position Marine Palynology and Paleoceanography (1.0 FTE)

The Department of Earth Sciences currently seeks a highly-motivated, high-potential applicant for a PhD position to work within the research project 'Paleoceanography of the ice-proximal Southern Ocean during past warm climates', in short 'OceaNice'. OceaNice is a research project funded by the European Research Council.

Antarctic ice sheets are destabilising because Southern Ocean warming causes basal melt. It is unknown how these processes will develop during future climate warming, which creates an inability to project ice sheet melt and thus global sea level rise scenarios into the future. Studying past geologic episodes, during which atmospheric carbon dioxide levels were similar to those projected for this century and beyond, is the only way to achieve mechanistic understanding of long-term ice sheet- and ocean dynamics in warm climates. Past ocean-induced ice sheet melt is not resolved because of a paucity of quantitative proxies for past ice-proximal oceanographic conditions: sea ice, upwelling of warm water and latitudinal temperature gradients. This hampers accurate projections of future ice sheet melt and sea level rise.

The CO2 of the mid-Pliocene (2.8-3.6 million years ago (Mya)), and mid-Miocene (13-17 Mya) was at times similar to that of the year 2100 under strong and moderate fossil fuel emission mitigation scenarios, respectively. Pliocene climates were 2.7-4.1°C warmer; Antarctic and Greenland ice sheets retreated inland and global average sea level was 20±10 meter higher compared to today. The uncertainty in Pliocene temperature and ice sheet size reflects our lack of understanding of the climate-ocean-ice sheet systems. Miocene ice-proximal Antarctic temperatures were even warmer; ice sheets were retreated inland. Sea ice and Southern Ocean ice-proximal upwelling were reduced in the Miocene. Quantitatively, however, the role of the ice-proximal oceanographic regimes, regional sea ice extent and upwelling intensity and the dynamics of ice-ocean contact during the Pliocene and Miocene are largely unknown.

The PhD candidate will generate records of dinocyst assemblages and organic geochemical biomarkers which will reveal sea ice cover, upwelling of warm deep-water, ocean frontal system behaviour and Southern Ocean latitudinal SST gradients. The candidate will use available and suitable sedimentary records while several ocean drilling campaigns will provide additional sedimentary archives from key regions around Antarctica. This project will reveal the role of ice-proximal oceanography in the documented extensive Pliocene and Miocene ice sheet retreats at key regions around Antarctica.

A Postdoctoral Researcher in the research project OceaNice will develop quantitative proxies for sea ice, upwelling of warm water and latitudinal temperature gradients using organic proxies: organic-walled dinoflagellate cysts and organic geochemical biomarker analyses, and apply these to late Pleistocene Antarctic-coastal and distal SO sedimentary records. The role of the PhD candidate is to apply these new tools for the first time on Pliocene and Miocene sediments to reveal the ice-proximal oceanographic conditions for these past warm climates. Another Postdoctoral Researcher in the project will use these new reconstructions to set up new numerical ocean model simulations for the Pleistocene, Pliocene and Miocene.

The project will involve active collaborations with researchers from numerous international institutions; sedimentologists, inorganic geochemists, seismic interpreters, terrestrial palynologists. Furthermore, the project will be undertaken in close collaboration with researchers at the Institute of Atmospheric Research Utrecht, where numerical model simulations will be performed, and for which exchange of expertise and intense collaboration is highly promoted.

The project leader and daily supervisor will be dr. Peter Bijl, and close collaboration in this project will be with dr. Francesca Sangiorgi and dr. Francien Peterse. During the project, the PhD candidate will also communicate and collaborate with physical oceanographers at the Institute of Atmospheric and Marine Sciences Utrecht (IMAU).

Up to 10% of the candidate's time will be dedicated to assisting in the BSc and MSc teaching programmes of the Earth Sciences Department. A personalised training programme will be set up, mutually agreed on recruitment, which will reflect the candidate's training needs and career objectives.