Additional Supervisor(s): Graham Shields (UCL Earth Sciences)
Earth’s climate has remained within habitable limits over thousands to millions of years, which implies the existence of feedback processes which prevent runaway greenhouse or icehouse states. Continental weathering of silicate rocks has been proposed to play the most important role in such climate stability, but is surprisingly poorly quantified. Therefore, both the rate at which the earth system is able to buffer past and future climate perturbations, and the associated biogeochemical changes in the ocean, are largely unknown.
Because the ocean is the ultimate repository for the particulate and dissolved products of continental denudation, ocean sediment cores represent unique archives of past weathering changes. In this project, you will develop and apply a novel combination of isotope tracers (e.g. Pb, Nd, Li isotopes) extracted from different fractions of marine sediment cores to quantify weathering changes in response to past climate perturbations.
This research will be carried out in state-of-the-art geochemistry labs and clean rooms within the LOGIC group at UCL. Here you will be well-placed to develop expertise in marine sediment extractions, chemical separations, and analysis of both radiogenic and non-traditional stable isotopes by multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS). Your research may be broadly aligned with the NERC-funded project ‘ISO-THERM’, which seeks to address the modern and Cenozoic operation of Earth’s thermostat. However, there is also wide scope to explore areas of your own interest, such as earlier intervals of Earth history, laboratory experiments, or interactions between the inorganic and organic carbon cycles.
Policy Impact of Research:
Natural weathering reactions will influence future atmospheric CO2 levels and climate trajectories, and will drive significant changes in marine productivity and ocean biogeochemistry.
Enhanced weathering reactions are a potential geoengineering tool, making it essential to quantify the controls on chemical weathering and its efficiency for CO2 drawdown.