This session will investigate how massive volcanism and meteorite impacts may have caused mass extinctions and global environmental crises. We hope to bring together researchers across the geological, geophysical, and biological disciplines to present new and exciting research. The session will focus on the six main Phanerozoic mass extinctions (end Ordovician, end Devonian, end-Permian, end-Triassic, end-Cretaceous), but contributions from theoretical studies or from other environmental crises (e.g. PETM) are also welcome.