An Ocean on Edge: how freshwater forcing modulates the strength and stability of Atlantic Overturning Circulation

This fully funded PhD scholarship provides an exciting opportunity to address critical uncertainties about the Atlantic Meridional Overturning Circulation (AMOC) by examining the role of freshwater in dramatic AMOC weakening during past climates. The successful candidate will work at the frontier between coupled climate model simulations and emerging decadally resolved stalagmite records of past climate change, focusing on the 8.2 ka event. The research will produce new simulations testing the climatic impact of freshwater addition to the North Atlantic, characterise the sensitivity of AMOC to changes in Northern Hemisphere ice sheet melting, reveal the processes driving AMOC collapse and allowing for its eventual recovery, and map the climatic footprint of the event. Conservative tracers and oxygen isotope tagging of water will be used in concert with other simulated climate variables to rigorously decode the geochemical signature in cave (stalagmite) records from around the North Atlantic region. To facilitate this research project at the frontier of modelling and proxy interpretation, the PhD student will complete several research stays at ETH Zurich, where the proxy records will be compiled and refined. This project addresses one of the greatest climate challenges today: the impact of ice melt on ocean circulation and the risk of AMOC disruption, which would cause massive upheaval in European and global climate, disrupting weather systems and driving climate extremes.