Review of carbon removal by ocean alkalinity enhancement (EU CRCF)

Ocean alkalinity enhancement (OAE) is a carbon dioxide removal method utilising carbonate chemistry to store CO₂ as dissolved inorganic carbon (DIC) in the ocean. The ocean already durably stores a huge quantity of DIC due to its high alkalinity, driven by natural rock weathering. However, quantification and certification for engineered OAE activities present challenges due to the large spatial and temporal scales on which CO₂ uptake from the atmosphere occur, the need for modelling to quantify removals, and the need for research and monitoring of ecological side-effects. This technical review for the European Commission explores these issues.

The review was led by Martin Johnson (Ecodiversity), with key contributions from Cerulogy and from Zara Popstoyanova (ICF). It was presented alongside contributions from experts in the field at a European Commission carbon removals workshop on ERW and OAE.