Ocean emissions of dimethyl sulfide into the atmosphere are projected to increase due to rising surface wind speeds and sea surface temperatures.

Ocean emissions of dimethyl sulfide (DMS) are a source of sulfur to the atmosphere, where its chemical processing contributes to aerosol formation, cloud formation, albedo and hence the Earth’s radiation budget. Climate model projections of DMS emissions, however, are inconsistent.
In this work, we employed machine learning models trained on global observations of biological processes to model emissions of DMS, which is produced by plankton. The models simulated seawater DMS concentrations from 1850 to 2100 using predictor variables from eight different climate models. The machine learning methods decreased the variation and improved the skill in predicting future DMS, reducing the large differences and biases observed in previous studies in terms of the future changes in the seawater DMS concentrations and sea-air flux estimates. Interestingly, although DMS concentrations in the ocean are predicted to decrease under future warming scenarios, emissions of DMS into the atmosphere are projected to increase due to rising surface wind speeds and sea surface temperatures. This finding contradicts current IPCC climate assessments that predict a decrease in DMS emissions due to global warming.
Because anthropogenic sulfur emissions are likely to decrease due to air quality policies, the relative importance of DMS to atmospheric sulfur and to aerosol formation is likely to grow, hence offsetting a small portion of climate warming.

Sankirna D. Joge, Karam Mansour, Rafel Simó, Martí Galí, Nadja Steiner, Alfonso Saiz-Lopez, and Anoop S. Mahajan. Climate warming increases global oceanic dimethyl sulfide emissions, PNAS. https://www.pnas.org/doi/full/10.1073/pnas.2502077122