The Impact of Dimethyl Sulfide Emissions on the Earth System

Dimethyl sulfide (DMS) is one of many biologically derived gases and particles emitted from the ocean that has the potential to affect climate. In the case of DMS it is oxidized to sulfate, which increases the aerosol loading in the atmosphere either through nucleation or condensation on other aerosols, which in turn changes the energy balance of the Earth by reflection of sunlight either through direct reflection by the aerosols or by modifying clouds. We have previously shown that the geographical distribution of DMS emission from the ocean may be quite sensitive to climate changes, especially in the Southern Ocean.

We have updated our state-of-the-art sulfur-cycle Earth system model (ESM), based on the Community Earth System Model (CESM) climate model, to include the indirect effect of DMS derived sulfate on clouds by using the Modal Aerosol Model (MAM), and have updated our ocean sulfur ecosystem model in light of updated ocean DMS observations.

We are now simulating the impact of DMS on the energy balance and climate of the Earth system, and its sensitivity/feedback to climate change. The estimate from our initial simulations is that DMS in the pre-industrial era is responsible for ~3.5 W/m2 of reflected sunlight, globally averaged (other preindustrial aerosols were included). Our next set of simulations will estimate the sensitivity/feedback to climate change, including the effects of anthropogenic aerosols.

Support for this work was provided through the Scientific Discovery through Advanced Computing (SciDAC) program funded by U.S. Department of Energy, Office of Science, Advanced Scientific Computing Research and Biological and Environmental Research. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.