Sulfur dioxide levels from industrial and auto emissions, biomass burning and soil dust are expected to increase in Asia as its population rises. Sulfur dioxide is converted into sulfate aerosols when emitted into the air. The ability of sulfate aerosols to reflect the sun's radiation may be one reason that increasing greenhouse gases have not warmed the Earth as much as some climate models have predicted.
Sulfates also contribute to local pollution and acid rain.
In the future, pollution in the tropics will increase, so we'd better understand it now. Kiehl and his colleagues want to understand how sulfate aerosols influence global climate so they can improve climate change models. Some physical and chemical processes in the Earth system are so complicated that modelers cannot simulate each detailed step. The observation region is downwind of the Indian subcontinent during the spring and extends into the pristine Southern Hemisphere. The direct effect of aerosols is the scattering that occurs when solar radiation bounces off particles in clear air.