Prof. Abbatt (University of Toronto) is recognized worldwide as a leader in atmospheric chemistry. He applies state-of-the-art experimental methods to study how aerosol particles promote cloud formation and interact with atmospheric gases, leading to improved model predictions of stratospheric ozone depletion, global and urban pollution, and climate change. His work bridges the atmospheric science and chemistry communities, and provides a firm foundation for quantitative assessments of societally-important environmental phenomena.