The AGU Centennial is about commemorating the past and looking into the future. The last century has been one of transformative discoveries in atmospheric science. These advancements, moreover, have been of tremendous benefit to society; for example, improved forecasts of extreme weather at longer lead times or more detailed projections of climate change impacts. Today, there remain many grand challenges in atmospheric science, such as cloud-aerosol interactions, or how the global atmosphere interacts with the ocean, land and cryosphere to produce a continuum of temporal and spatial variability. To celebrate past accomplishments and highlight future challenges, we propose an all-day session of oral presentations by a diverse group of invited speakers – both established and emerging leaders in the field – and all excellent communicators. A brief sample of topics includes: ozone depletion and recovery, weather and climate prediction, detection and attribution of climate change, and extreme events.