Latitude Dictates Global Marine Diatom Dynamics: Insights From 25 years of Satellite Data

Abstract Marine diatoms are key players in global biogeochemical cycles, yet their spatiotemporal dynamics and the underlying drivers remain poorly understood. Here, we developed a novel remote sensing model and utilized 25 years of global satellite data to investigate marine diatom biomass. Our observations reveal distinct latitude‐dependent distributions, with higher biomass in high‐latitude and coastal waters. Trend analysis reveals a widespread increase in diatom biomass across most ocean regions, with significant growth rates ranging from 0.1 to 1.6 × 10 −5 mg m −3 per month. This trend stands in sharp contrast to the declines observed in equatorial waters and is accompanied by pronounced seasonal oscillations. Causality analysis identifies sea surface temperature, mixed layer depth, and photosynthetically active radiation as dominant drivers of diatom dynamics in mid‐latitudes. Nutrients, particularly nitrate in subtropical waters and silicate, also exert a significant influence. While broad‐scale climate indices showed limited explanatory power for global diatom anomalies, their impact was most evident in equatorial oceans. These findings provide the first comprehensive view of the multifaceted drivers of global marine diatom dynamics, offering crucial insights into their role in ocean biogeochemistry and responses to environmental change.