Ocean Biological Sources of Sulfate Aerosols More Sensitive to Climate Change than Previously Estimated
Ocean biological activity is a natural source of atmospheric aerosols. These aerosols cool climate directly by blocking incoming radiation in the atmosphere and indirectly by enhancing cloud brightness. DOE-funded scientists modeled the influence of climate change on these ocean biological aerosol sources. Biological sources generate the gas dimethyl sulfide (DMS) in the ocean, which is converted to sulfate in the atmosphere. Model simulations for the start and end of the 21st century predicted large changes in DMS flux to the atmosphere of over 150% in the Southern Ocean. This was due to concurrent sea ice changes and ocean ecosystem composition shifts caused by changes in temperature, mixing, nutrients, and light regimes. The largest changes occurred in high latitudes, a region already sensitive to climate change so that any local feedback of DMS on clouds, and thus radiative forcing, would be particularly important. Comparison of these results to prior studies showed that the increasing model complexity used in this study predicted reduced DMS emissions at the equator and increased emissions at high latitudes, suggesting that the sensitivity of DMS to climate change could be much greater than previously estimated.
Cameron-Smith, P., S. Elliott, M. Maltrud, D. Erickson, and O. Wingenter. 2011. “Changes in Dimethyl Sulfide Oceanic Distribution Due To Climate Change,” Geophysical Research Letters 38, L07704. DOI: 10.1029/2011GL047069.