The biogeochemistry of marine dimethylsulfide

Dimethylsulfide is produced in the ocean, and its emission drives the formation of atmospheric aerosols that cool the climate. This Review discusses the production of dimethylsulfide, its cycling in the ocean and atmosphere and its broader radiative effects. The marine trace gas dimethylsulfide (DMS) supplies sulfur to the atmosphere at a rate of 15-40 Tg S per year, contributing to the production of atmospheric sulfate aerosols that influence cloud radiative properties and thereby climate. The resulting climate cooling effect of DMS is an estimated -1.7 to -2.3 W m(-)(2), which is similar in magnitude to the warming effect of anthropogenic CO2 emissions (1.83 +/- 0.2 W m(-)(2)). In this Review, we describe the production and cycling of marine DMS and its fate in the atmosphere. Advances in molecular genetics and large-scale biogeochemical measurements have revealed the global prevalence of DMS-related processes, including in previously overlooked environments and organisms, such as sediment-dwelling bacteria. Most marine DMS (>90%) is degraded or consumed in the water column, but the remainder is emitted to the atmosphere, where it contributes to the formation of cloud condensation nuclei. Large uncertainties (up to +/- 10 W m(-)(2)) associated with the global impact of DMS emissions arise from the use of crudely defined biological parameters, such as total chlorophyll, in models. Constraining and modelling the biogeochemical processes that control DMS production are key to better estimating the influence of DMS on climate.