Supplementary material to "Efficiency metrics for ocean alkalinity enhancement under responsive and prescribed atmosphere conditions"

1 Analytical equality of η(t) and direct atmosphere removal Consider a simple box model comprising an atmosphere box of finite volume, and an ocean mixed layer box, as shown in Figure S1.The intent is not to create a model with detailed realism but to demonstrate the consequences of modelling the atmosphere to be finite, and therefore change its pCO 2 in response to fluxes of CO 2 across the air-sea interface.