乌得勒支大学2018年招聘博士后（孢粉学/古海洋学方向）

Postdoctoral Researcher in Paleoceanography/Palynology

Utrecht University - Faculty of Geosciences

Utrecht, Netherlands

Job description

The Department of Earth Sciences currently seeks a highly-motivated, high-potential applicant for a position as a Postdoctoral Researcher 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 (SO) 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 (CO2) 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.

OceaNice will provide an integral understanding of the role of oceanography in ice sheet behaviour during past warm climates, as analogy to the future. The postdoctoral researchers role in the project will be to 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.

Variations in SO frontal systems are particularly well-documented for late Pleistocene (past 1 million year) glacial-interglacial cycles with the use of calcite and siliceous microfossils and their geochemistry. However, diagenetic effects, dilution and dissolution of these microfossils hamper their application to relevant warm time slices further back in time, and closer to the ice sheet. Dinocyst-based proxies for sea surface temperature, upwelling and sea ice are not affected by these factors, and can therefore be applied to older warm time intervals. Modern dinocyst biogeographic patterns in the SO are clearly tied to sea ice extent, upwelling and warm, oligotrophic surface water conditions, but SO dinocyst records straddling Pleistocene glacial-interglacial cycles are scarce. The postdoctoral researcher will reconstruct the latitudinal SST gradient, locus and strength of circumpolar deep water upwelling and sea ice extent over Pleistocene glacial-interglacial cycles using dinocyst assemblages and (novel) biomarker proxy records for absolute sea surface temperature. These new reconstructions will provide constraints to ice-proximal SO paleoceanographic conditions. More importantly, applying dinocyst-based proxies on records at the subtropical front (STF) with well-documented oceanographic changes will allow calibration of dinocyst- and novel biomarker-based proxies to the known oceanographic change. This will enable accurate quantitative paleoceanographic reconstructions for crucial time slices further back in time, where conventional tools cannot be applied.

About the team

A PhD student in the project will apply the new tools to two past warm climate states, during which CO2 was comparable to that of the future under strong and moderate fossil fuel emission mitigation scenarios. Later on in the project, another postdoctoral fellow will interpolate between these new reconstructions using high-resolution ocean circulation modeling for circum-Antarctic quantification of past oceanographic conditions, which will be implemented into new ice sheet model simulations.

The postdoc will be supported in the laboratory by a technician hired in the project to assist in the palynological and organic geochemical sample preparation. 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 postdoctoral researcher will also communicate and collaborate with physical oceanographers at the Institute of Atmospheric and Marine Sciences Utrecht (IMAU).

Qualifications

We seek a highly motivated postdoctoral candidate with excellent communication skills and a PhD degree with experience and background in Southern Ocean paleoceanography, and ideally but not necessarily (dinocyst) micropaleontology and/or organic geochemistry. The best candidates also have laboratory (gas/liquid chromatography) and/or microscope experience. The researcher should have affinity with light microscope work. Given the project includes close collaboration with physical oceanographers applying numerical ocean models, some affinity with numerical modelling is appreciated.

Applicants must have excellent written and spoken English skills and be highly motivated to work in an international team with a common objective. Within the project scope as outlined above, we expect the candidate to be an independent thinker, with a collaborative mindset.