My research focuses on aerosol-cloud interactions in warm, mixed-phase and ice clouds and their importance for the radiation budget and the hydrological cycle by developing improved parameterizations of cloud microphysics and aerosol-cloud interactions in regional and global climate models. We also conduct field experiments and laboratory studies on various aerosol-cloud interactions. I have published more than 250 peer-reviewed articles and was a lead author in the 4th and 5th IPCC Assessment Reports. I am a fellow of the American Geophysical Union and I received an honorary doctorate from University of Stockholm in 2018.