One-third of Southern Ocean productivity is supported by dust deposition.

• Published in: Nature
• Main Authors: Weis, Jakob, Chase, Zanna, Schallenberg, Christina, Strutton, Peter G, Bowie, Andrew R, Fiddes, Sonya L
• Format: Article in Journal/Newspaper
• Language: English
• Published: Nature Publishing Group 2024
• Subjects: Southern Ocean
• Online Access: https://doi.org/10.1038/s41586-024-07366-4; https://pubmed.ncbi.nlm.nih.gov/38750234

Natural iron fertilization of the Southern Ocean by windblown dust has been suggested to enhance biological productivity and modulate the climate1-3. Yet, this process has never been quantified across the Southern Ocean and at annual timescales4,5. Here we combined 11 years of nitrate observations from autonomous biogeochemical ocean profiling floats with a Southern Hemisphere dust simulation to empirically derive the relationship between dust-iron deposition and annual net community production (ANCP) in the iron-limited Southern Ocean. Using this relationship, we determined the biological response to dust-iron in the pelagic perennially ice-free Southern Ocean at present and during the last glacial maximum (LGM). We estimate that dust-iron now supports 33% ± 15% of Southern Ocean ANCP. During the LGM, when dust deposition was 5-40-fold higher than today, the contribution of dust to Southern Ocean ANCP was much greater, estimated at 64% ± 13%. We provide quantitative evidence of basin-wide dust-iron fertilization of the Southern Ocean and the potential magnitude of its impact on glacial-interglacial timescales, supporting the idea of the important role of dust in the global carbon cycle and climate6-8.