Lavinia Patara

The proposed project addresses a key challenge in our understanding of the future evolution of the Earth’s oceans and climate. Atmospheric concentrations of CO2, a strong greenhouse gas, are determined not only by anthropogenic carbon emissions but also by ocean uptake of CO2. This project focuses on the Southern Ocean CO2 uptake using global ocean-biogeochemistry simulations for the 20th and 21st centuries. The Southern Ocean is of unique importance for air-sea CO2 exchanges at a global scale due to its vigorous meridional overturning circulation and CO2 uptake potential. Yet there is still large uncertainty regarding ist role in the ocean CO2 uptake in both present climate and for the next century. One reason for this is the lack of explicit simulation of ocean mesoscale eddies within climate-carbon cycle projections. Mesoscale eddies, i.e. small-scale rings shed by current instabilities, are known to be critical in determining the redistribution of tracers within the Southern Ocean. This project will assess the role of Southern Ocean mesoscale eddies on the ocean uptake of CO2 and on its ventilation pathways under present climate and under anthropogenic warming projections for the 21st century. Today’s supercomputing resources are still not sufficient to simulate ocean biogeochemistry in an eddy-resolving global model. Here an innovative “two-way” nesting technique will thus be used to enhance the ocean model resolution over key areas of Southern Ocean airsea CO2 exchange. The model framework will be further developed to include an inorganic carbonate chemistry module. A set of simulations using different ocean resolutions and atmospheric forcing will assess the role of mesoscale eddies on the ocean CO2 uptake in a changing climate. Because of the global scope of the simulations, not only the Southern Ocean CO2 uptake, but also i) other ocean regions and ii) other anthropogenic impacts on the ocean (e.g. sea level changes and ocean acidification) can be investigated.