The flux of DMS from the ocean to the atmosphere plays a major role in the marine atmospheric sulfur cycle.The oxidation of this biogenic sulfur to SO2 and subsequently to sulfate aerosol (which can act as cloud condensation nucleii) has long been postulated to link DMS and climate (e.g.Charlson et al.,1987).Increased CCN number results in brighter,longer-lived clouds for a given liquid water content,and hence exerts a cooling effect on the Earth’s climate.