Anoxic events with euxinic (anoxic, sulfidic) conditions have been linked to extreme episodes of volcanic outgassing. Volcanism contributed to the buildup of CO in the atmosphere and increased global temperatures, causing an accelerated hydrological cycle that introduced nutrients into the oceans (stimulating planktonic productivity). These processes potentially acted as a trigger for euxinia in restricted basins where water-column stratification could develop. Under anoxic to euxinic conditions, oceanic phosphate is not retained in sediment and could hence be released and recycled, aiding perpetual high productivity.