Daniel Patrick Dauhajre, Tom Bell, David Siegel

There is a growing interest in sequestering carbon dioxide via cultivation and sinking of seaweed in the ocean. Robust quantification of the viability of this marine carbon dioxide removal (mCDR) strategy requires deployment and interrogation of computer simulations that resolve coupling between turbulent oceanic circulation, biogeochemical fluxes, and cultivated seaweed with regional granularity. This white paper describes considerations that inform the design of a virtual mCDR experiment in the Southern California Bight (SCB) that targets glob- ally meaningful scales of CDR. For the SCB, we define an array of farm elements that share design features with present-day farms (e.g., cultivation on long-lines), but are approximately O(1000) times larger in area. The simulated farm area is based on an assumption of a biomass yield that is 5× more efficient than present day farms, and the number of farms is chosen to meet a regional CDR target of approximately 0.01 Gt CO2 / year (~10% of the global mCDR target). The placement of the farms in the SCB for the virtual mCDR experiment is guided by model constraints, anticipated nutrient availability, an assumption of local seaweed sinking in deep water, and avoidance of human conflict zones.