Reduced estimate of global marine primary productivity and hemispheric redistribution over the satellite era

Marine net primary productivity underpins ocean food webs, global fisheries, and the ocean’s role in the carbon cycle, yet its global magnitude and long-term evolution remain highly uncertain. Here, we compile an expanded global database of field net primary productivity measurements determined by carbon isotope incubation, increasing observational coverage by ~50% relative to existing compilations. We observe spatially varying agreement between satellite products and in situ observations, motivating the development of an observationally constrained model that integrates field measurements with environmental predictors. This model demonstrates improved predictive skill and yields revised global net primary productivity estimate ~10–20% lower than conventional satellite products. Reconstructions over the satellite era further reveal a pronounced hemispheric redistribution of net primary productivity, characterized by increasing spatial heterogeneity in the Northern Hemisphere and progressive homogenization in the Southern Hemisphere. These findings refine both the magnitude and spatial structure of marine productivity and have implications for understanding the ocean carbon cycle under ongoing climate change. Global marine net primary production is 10–20% lower than estimated by conventional satellite products with a pronounced hemispheric redistribution over the past two decades, according to a global database of field measurements determined by carbon isotope incubation.