Carbon fluxes and inventory of the Norwegian Sea with a view towards seaweed carbon dioxide removal

We use a coupled 3D physics-biology-biogeochemistry ocean model to provide a carbon inventory for the Norwegian Sea from 1997 to 2024. The inventory involves the main states of the ocean carbon system, including Dissolved Inorganic Carbon (DIC), total carbon (CT), and alkalinity (AT). We also provide trends on the pCO2 and the carbon fluxes involved, both CO₂ fluxes through the atmosphere-ocean interface and vertical and horizontal advection of DIC. Export by biological carbon pumping is also considered. The results indicate that the Norwegian Sea surface is a net sink of CO₂, and that the flux of CO₂ through the surface increased substantially from 1997 to 2024. The total content of DIC remained relatively stable, and there was a net transport of DIC and CT out of the Norwegian Sea seen as a whole. This advective transport is quantified. The simulation data is compared with previous observations and estimates of both total carbon and carbon fluxes in the Norwegian Sea, the North Sea and parts of the North Atlantic. Recent empirical work has provided budgets for the carbon export (particulate and dissolved organic carbon) from seaweed farming in the Norwegian Sea. We use the simulations results with these empirical results to discuss the potential for using seaweed CDR for carbon sequestration in the Norwegian Sea in particular, and the Northern North Atlantic in general.