His research focuses on the use of models to understand the long-term changes of short-lived climate forcers (i.e. ozone, aerosols, and methane). He has published several papers focusing on the transient behavior of tropospheric chemistry since the mid-nineteenth century. In particular, he has made use of ice-core measurements of black carbon and sulfate aerosols to validate model simulations of those compounds. Other applications include the modeling of paleo-atmospheres under massive chemical perturbations.