The 2017 boreal wildfire season punctuated an apparent evolution toward new anomalies in wildfire behavior, explosive pyroconvection, and hemisphere-scale smoke plumes. For instance, a wildfire complex in western Canada erupted into at least five pyrocumulonimbus (pyroCb) storms on 12 August, generating a stratospheric smoke pall that may have been unprecedented in the satellite era (post 1978). Observations across the northern hemisphere revealed previously unequaled plume concentration, mass burden, optical/physical properties, and altitude. In another apparent first for Europe, wildfires in Portugal exploded into pyroCbs in June 2017. Our motive for this session is to discuss and assess the impact of these (and other) unusually extreme fire events on communities, weather, and climate. We solicit reports on these specific events, and upper atmosphere smoke plumes in general. Contributions to this session may address several important science questions, e.g. the challenges and potentials imposed on remote sensing systems by these unprecedented events, the true abnormality of the fuel/fire/plume dynamics leading to pyroCb plumes in the upper troposphere and lower stratosphere, the hemispheric atmospheric impact, and our modeling/predictive capability. We solicit papers on remote sensing (active and passive), and in situ measurements, and modeling.