Since calcification releases CO₂ as a by-product, any changes to the rate of biotic calcification in response to interventions to the surface ocean — like adding alkalinity or removing CO₂ — must be considered. Changes in biotic calcification rates could occur in both coastal and open ocean waters, and at the level of individual calcifiers or calcifier populations. In practice, quantifying the biotic calcification response to alkalinity addition may pose significant spatial, temporal, and signal-to-noise challenges.