A snag for nutrient fertilization: decoupled production and export

John Tracey, Manon Duret, Lionel Guidi, Corinne Le Quéré, Simon Ramondenc, Alessandro Tagliabue , B. B. Cael

Interest in nutrient fertilization waned after inconclusive field experiments, but has resurged. Collating Southern Ocean \textit{in-situ} observations and available fertilization simulations, we find phytoplankton primary production and organic carbon export are uncorrelated in the largest high-nutrient-low-chlorophyll (HNLC) region, while model estimates cast doubt on realistic deployments achieving large amounts of carbon removal. Therefore, sequestering carbon by supplying limiting nutrients appears unproven, and further evidence is required before credits are issued.