Coastal upwelling systems account for approximately

half of global ocean primary production and contribute

disproportionately to biologically driven carbon sequestration.

Diatoms, silica-precipitating microalgae, constitute

the dominant phytoplankton in these productive regions,

and their abundance and assemblage composition in the sedimentary

record is considered one of the best proxies for primary

production. The study of the sedimentary diatom abundance

(SDA) and total organic carbon content (TOC) in the

five most important coastal upwelling systems of the modern

ocean (Iberia–Canary, Benguela, Peru–Humboldt, California,

and Somalia–Oman) reveals a global-scale positive

relationship between diatom production and organic carbon

burial. The analysis of SDA in conjunction with environmental

variables of coastal upwelling systems such as upwelling

strength, satellite-derived net primary production, and surface

water nutrient concentrations shows different relations

between SDA and primary production on the regional scale.

On the global scale, SDA appears modulated by the capacity

of diatoms to take up silicic acid, which ultimately sets

an upper limit to global export production in these ocean regions.