Various phytoplankton groups contribute differently to the emission of dimethyl sulfide (DMS), which affects atmospheric sulfate aerosol loading and cloud brightness. Shifts in phytoplankton community composition without changing total biomass could potentially influence clouds and climate via the sulfur cycle.
Marine ecosystems and the DMS production were dynamically calculated in climate projections for the first time. This study shows that changes in phytoplankton community structure have significant impacts on sulfate aerosol burden and surface temperature, especially on the regional scale.
Dimethyl sulfide (DMS), primarily produced by marine organisms, contributes significantly to sulfate aerosol loading over the ocean and plays an important role in modifying cloud properties. Changes in marine ecosystems, such as phytoplankton physiology and community structure, could affect climate via the sulfur cycle. A fully coupled Earth system model, including explicit marine ecosystems and the sulfur cycle, is used here to investigate the impacts of changes associated with individual phytoplankton groups on DMS emissions and climate. Simulations show that changes in phytoplankton community structure, DMS production efficiency and interactions of multi-element biogeochemical cycles can all lead to significant differences in DMS transfer to the atmosphere. We find the global mean surface temperature increases due to DMS production changes associated with individual phytoplankton group. Changes in DMS emissions, radiative effect, and surface temperature are more intensive on regional scales. This study suggests that major uncertainties associated with future marine sulfur cycling may involve strong region-to-region climate shifts.