Atmospheric pCO₂ Response to Stimulated Organic Carbon Export: Sensitivity Patterns and Timescales

The ocean's organic carbon export is a key control on atmospheric pCO 2 and stimulating this export could potentially mitigate climate change. We use a data‐constrained model to calculate the sensitivity of atmospheric pCO 2 to local changes in export using an adjoint approach. A perpetual enhancement of the biological pump's export by 0.1 PgC/yr could achieve a roughly 1% reduction in pCO 2 at average sensitivity. The sensitivity varies roughly 5‐fold across different ocean regions and is proportional to the difference between the mean sequestration time τ seq of regenerated carbon and the response time τ pre of performed carbon, which is the reduction in the preformed carbon inventory per unit increase in local export production. Air‐sea CO 2 disequilibrium modulates the geographic pattern of τ pre , causing particularly high sensitivities (2–3 times the global mean) in the Antarctic Divergence region of the Southern Ocean.