The main goal of Jacobson's research is to understand physical, chemical, and dynamical processes in the atmosphere better in order to address atmospheric problems, such as climate change and urban air pollution, with improved scientific insight and more accurate predictive tools. He also evaluates the atmospheric effects of proposed solutions to climate change and air pollution, examines resource availability of renewable energies, and studies optimal methods of combining renewables. To accomplish many of these goals, he has developed and applied numerical solvers to simulate gas, aerosol, cloud, radiative, and land/ocean-surface processes. In 1993-4, he developed the first gas-aerosol-radiative air-pollution model with interactive feedback to weather on any scale. In 2001, he invented the nested global-through-urban air-pollution-weather-climate model. In 2000, he discovered that black carbon, the main component of soot particles, may be the second-leading cause of global warming after carbon dioxide. He has also demonstrated and quantified the effect of carbon dioxide on human health through its feedback to air pollution, examined the relative effects of greenhouse gases versus aerosols on global climate, the effects of aerosols on ultraviolet radiation, the effects of aerosol mixing state on atmospheric heating, the effects of biomass burning on climate, the effect of hydrogen fuel cells on air pollution and the ozone layer, the effects of aerosols on winds and precipitation, the effects of ethanol and diesel vehicles on air quality, and the effects of agriculture on air pollution. To date, he has published two textbooks and over 80 peer-reviewed journal articles. Several hundred researchers have used computer models that he has developed. In 2005, he received the American Meteorological Society Henry G. Houghton Award for "significant contributions to modeling aerosol chemistry and to understanding the role of soot and other carbon particles on climate." His recent paper, "Effects of ethanol versus gasoline on cancer and mortality in the United States" was the top-accessed article in the Journal Environmental Science and Technology for April-September, 2007.