A new study published in the Journal of Geophysical Research: Biogeosciences offers fresh insight into how the Chicxulub asteroid impact 66 million years ago triggered the mass extinction that wiped out the dinosaurs. Researchers found that the collision generated a vast cloud of extremely fine dust that superheated Earth's upper atmosphere, effectively broiling exposed living organisms and sparking widespread wildfires within the first hour or two after impact.

The study builds on the well-established Alvarez hypothesis and combines earlier impact simulations with newly identified geological evidence, including a layer of ultra-fine post-impact dust discovered in 2023. Purdue University planetary scientist Brandon Johnson and colleagues calculated that this dust, formed from leftover vaporised rock, would have exposed organisms to roughly 17 times the lethal human radiation dose, causing severe burns and heat stroke even in thick-skinned dinosaurs. While the heat pulse likely wasn't intense enough to ignite wood directly, it would have been more than sufficient to set grass, lichen and pine needles ablaze, fuelling extensive fires across the planet.