Dust-Iron Fertilisation Supports One-Third of Southern Ocean Productivity

Iron fertilisation by windblown mineral dust has been proposed to enhance biological productivity in the Southern Ocean. However, observational evidence of its impact across the basin and at annual timescales has historically been limited due to the scarcity of direct observations. Robotic ocean profiling floats now provide the necessary data to address this question. In a recent study, researchers from the University of Tasmania and Commonwealth Scientific and Industrial Research Organisation (CSIRO) combined eleven years of nitrate measurements from biogeochemical Argo floats with a dust simulation to determine the relationship between dust-iron deposition and annual net community production (ANCP) in the iron-deficient Southern Ocean. The study estimates that dust-iron currently supports 33% of Southern Ocean ANCP. During the last glacial maximum, when dust deposition was significantly higher, dust-iron contributed twice as much. These findings underscore the key role of dust in the global carbon cycle and climate.

Reference: Weis, J., Chase, Z., Schallenberg, C., et al. (2024). One-third of Southern Ocean productivity is supported by dust deposition. Nature, 629, 603–608. https://doi.org/10.1038/s41586-024-07366-4