My research interests are in climate modeling, aerosol-cloud-climate interactions, air quality, and environmental science and engineering. Aerosols (or “particulate matter”) reflect incoming radiation and exert a cooling effect on climate, opposing the warming of greenhouse gases (GHG). Aerosol effects on climate, unlike greenhouse gases, are not well understood but are important for predictions of future climate change. Aerosols have likely “masked” additional warming from greenhouse gases, confounding the sensitivity of climate to greenhouse gases, which is an important parameter for climate models. Particulate pollution also has adverse human health effects. Hundreds of thousands of premature deaths every year can be attributed to air pollution. As governments introduce measures to reduce climate-cooling particulate pollution, we will see the unfortunate side effect of increasing global warming.

Specific areas of focus include:

  • Assessing future climate forcing and response. Projections of future greenhouse gas and aerosol emissions are determined by models that consider future population and socioeconomic factors. These projections are implemented in a fully coupled global earth system model (developed by GFDL) and used to determine future changes in climate response (temperature, precipitation, etc.) on a global and regional scale.

  • The effect of climate change on aerosol concentrations. Even if society was able to keep particulate pollution emissions steady at present-day levels, concentrations of these climate-forcing and human health-impacting particles would still be on the rise in the future. This is due to climate factors such as temperature, precipitation, relative humidity, and others, which impact formation of atmospheric aerosols. For example, as temperature increases due to greenhouse warming, chemical reaction rates favoring sulfate aerosol formation are enhanced.

  • New particle formation and aerosol physics. Besides being directly emitted, aerosol particles can be formed via a nucleation process in which metastable atmospheric gas molecules cluster together to form small particles. Understanding this source of particles and their impact on climate is currently an area of ongoing research.