Sub-Polar North Atlantic ocean dynamics in a 3ºC warmer world

About the Project

Northwest Eurasia owes its anomalously temperate climate to the oceanic circulation cell known as the Atlantic Meridional Overturning Circulation (AMOC). Regional warmth is maintained by northward-flowing Atlantic surface currents – including the Gulf Stream – that lose their heat to the atmosphere in the mid-to-high latitudes, before sinking as cold and saline waters in the Nordic seas. These dense bottom waters then flow south over sills either side of Iceland before combining to contribute >85% of the deep-water return flow of the AMOC. Anthropogenic climate change will warm and freshen the surface waters of the sub-Polar North Atlantic, reducing their density and possibly inhibiting the formation of deep waters. Such a break in this critical region of overturning may slow down or even shut down the AMOC, which is highlighted as a global tipping point of major concern by the Intergovernmental Panel on Climate Change (IPCC).

This project seeks to understand the operation of this sub-polar component of the AMOC in the most recent past climate, the Pliocene, which had similar global temperatures to those predicted for the near future. Recently published work, based on new core material from International Ocean Discovery Program (IODP) Expedition 395 (June-August 2023), has shown tipping point behaviour during the Pliocene in the deep-water return flow of the AMOC (Sinneseal et al. 2025). The aim of this project is to generate thermo-haline (temperature-salinity) reconstructions of the surface ocean in the critical sub-Polar North Atlantic zone, to understand surface ocean density controls on this tipping point in deep-water formation. These reconstructions will be based around the paired measurements of both stable isotopes and trace metal concentrations (Mg/Ca) in planktic (surface ocean) and benthic (deep ocean) foraminifera shells, and/or the analysis of organic biomarkers, preserved in sediment cores from IODP Exp. 395 sites. The project will build on existing post-expedition sample processing and pilot analyses.

This project is not associated with funding from the University of Birmingham. Applicants will need to obtain their own scholarship or other financial support to cover tuition fees and living costs. All interested candidates MUST contact the lead supervisor of this project by email, including a current CV and statement of interest BEFORE submitting a formal application.

Please note this research topic is also available for students on a 1-year MSc by Research course: https://www.birmingham.ac.uk/study/postgraduate/subjects/geography-earth-and-environmental-sciences-courses/earth-sciences-research-msc

References

Sinnesael, M., Boris Th Karatsolis, B. Th., Pearson, P.N., Briais, A., Hemming, S.R., LeVay, L.J., Dunkley Jones, T., et al. 2025. Onset of strong Iceland-Scotland overflow water 3.6 million years ago. Nature Communications. doi.org/10.1038/s41467-025-59265-5.