Silica and the cycle of carbon in the ocean

Silicon is a key element whose major role in the control of the cycle of carbon in the ocean has been recently revealed. This is first illustrated through the resolution of the ‘opal paradox’ in the modern Southern Ocean. Second, the ‘silica hypothesis’ explains why, during the Last Glacial Maximum, the atmospheric concentration of CO2 was about 40 % below that of the interglacial period. Increased deliveries of wind-borne silica to the surface ocean as well as of riverine inputs favoured the dominance of diatoms over coccolithophorids, resulting in a net emission decrease of CO2 by coccolithophorids from the ocean surface to the atmosphere. To cite this article: P. Tréguer, C. R. Geoscience 334 (2002) 3–11