Heat and Wildfires During the K-Pg Mass Extinction Enhanced by Fine Dust

Abstract

The primary kill mechanisms responsible for the K-Pg mass extinction, including the end of the dinosaurs, are much debated. Here, we reexamine the hypothesis that heat and fire were the primary kill mechanisms for terrestrial organisms during the K-Pg mass extinction. We show that spherules and uncondensed vapor from the impact vapor plume are first ballistically transported globally and then decoupled spatially from one another when they encounter the atmosphere. Expanded K-Pg boundary sections provide strong evidence that this impact vapor ultimately condenses to abundant fine dust. The flux of thermal energy produced by impact spherules entering the atmosphere globally is strongly enhanced by the presence of this fine dust. This supports the idea that heat and fire were key kill mechanisms for terrestrial organisms.