Examine and quantifying the potential of artificial upwelling for its capacity for additional CO2 uptake and long-term storage in the ocean

Over the last few years, several carbon dioxide removal (CDR) methods have received attention as potential tools to introduce negative CO₂ emissions to the Earth system to compensate future remaining CO₂ emissions and thus, to stabilize global mean surface air temperature. Artificial upwelling (AU) has been proposed as a marine CDR method and describes the idea of deploying vertical pipes in the open ocean to upwell nutrient rich deep water to the surface to fertilize the marine ecosystem and stimulate the carbon flux from the atmosphere into the interior ocean via the biological carbon pump. However, its potential as a marine CDR method and a refined and quantitative understanding of the underlying process stimulated via AU is lacking. To close these knowledge gaps, we simulate the large-scale deployment of AU within the UVic 2.9 Earth system model of intermediate complexity during future climate change scenarios.

The results discussed in this thesis lead to the overall conclusions that (i) the initial biology-focused narrative of AU misses quantitatively important processes associated with the solubility pump and that (ii) AU does not significantly cause negative CO₂ emissions to the Earth system without simultaneously fertilizing the ecosystem with additional iron. However, (iii) AU is effective in reducing global mean surface air temperature via its direct impact on the redistribution of heat in the Earth system.