Ms Jess Crumpton-Banks
I studied Environmental Geoscience (MSci) at the University of Bristol, graduating in 2015. My PhD project focuses on the role of the Southern Ocean in influencing atmospheric CO2 over recent glacial-interglacial cycles. Ice core records from Antarctica show us that Antarctic air temperature and atmospheric CO2 have been tightly coupled over the last 800,000 years, though the exact cause for this is unknown. The oceans are the largest reservoir of carbon that can equilibrate with the atmosphere on the thousand-year timescales observed, suggesting the oceans as a driver for glacial-interglacial CO2 change. The Southern Ocean is considered a prime candidate because at present it is a “leak” of CO2 to the atmosphere. Currently old, carbon-rich deep water upwells in the Southern Ocean and outgasses to the atmosphere. Studies suggest the CO2 leak from the Southern Ocean was stemmed during glacial periods, resulting in lower atmospheric CO2 concentrations. The two current main hypotheses are either 1) increased sea ice cover or 2) enhanced surface stratification. Both would impose a physical barrier to carbon-rich waters upwelling to the surface, but each scenario would result in a different sea surface pH. Increased sea-ice cover would trap the acidic deep waters at the surface, resulting in a lower sea surface pH than in the case of enhanced surface stratification, where gas exchange could still occur at the air-sea interface. This project aims to reconstruct sea surface pH in the Southern Ocean over recent glacial cycles using boron isotopes (a proxy for pH).
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