Re-visiting the CLAW hypothesis

Environmental context. Over the last twenty years, large and continued research efforts have been invested in deciphering whether oceanic plankton contribute to the regulation of climate by the production and release of cloud-seeding atmospheric sulfur. Our recent research using globally spread observations and satellite-derived data suggest that biogenic sulfur from the oceans represents a major source of cloud-forming aerosols over much of the pristine southern hemisphere oceans. These climate-cooling sulfur emissions respond positively to incoming solar radiation over seasonal cycles, but show a weak response to anthropogenic global warming foreseen for the current century.