Testing Earth’s weathering thermostat with novel isotope tracers

Earth’s climate has remained within habitable limits over millions of years, implying that feedback processes prevent runaway greenhouse or icehouse states. Continental weathering of silicate rocks has been proposed to play the most important role in climate stability, but it is surprisingly poorly quantified, and this premise has recently been challenged. Therefore, the rate at which the earth system can buffer past and future climate perturbations is largely unknown.

Regions with high weathering rates today, such as the Himalayas and tropical islands, serve as excellent natural laboratories. Furthermore, the ocean is the ultimate repository for the particulate and dissolved products of continental denudation, so marine sediment cores provide unique archives of past weathering changes. In this project, you will apply a novel combination of isotope tracers (e.g. Pb, Nd, Li isotopes) in different fractions of marine sediment cores to quantify weathering changes in response to Cenozoic climate perturbations.

This research will be carried out in state-of-the-art geochemistry labs in the LOGIC group at UCL. You will develop expertise in marine sediment extractions, chemical separations, and radiogenic and non-traditional stable isotope measurements by multi-collector inductively-coupled plasma mass spectrometry (MC-ICP-MS). The findings will build towards a better quantification of past carbon cycle changes, with potential implications for future climate and geoengineering.