Dimethylsulfide or DMS is an organosulfur compound with the formula (CH3)2S. It is the most abundant biologically-produced sulfur compound to be found in the atmosphere, being emitted to the air primarily by marine phytoplankton. P
erhaps its greatest claim to fame is that several years ago Charlson et al. (1987) discussed the plausibility of a multi-stage negative feedback process, whereby warming-induced increases in the emission of DMS from the world’s oceans tend to counteract the effects of the initial impetus for warming. The basic tenant of their hypothesis was that the global radiation balance is significantly influenced by the albedo of marine stratus clouds (the greater the cloud albedo, the less the input of solar radiation to the Earth’s surface). The albedo of these clouds, in turn, is known to be a function of cloud droplet concentration (the more and smaller the cloud droplets, the greater the cloud albedo and the reflection of solar radiation), which is dependent upon the availability of cloud condensation nuclei on which the droplets form (the more cloud condensation nuclei, the more and smaller the cloud droplets). And in completing the negative feedback loop, Charlson et al. noted that the cloud condensation nuclei concentration often depends upon the flux of biologically-produced DMS from the world’s oceans (the higher the sea surface temperature, the greater the sea-to-air flux of DMS).