The Chicxulub impact may have turned Earth's surface into a furnace shortly after the collision. A new study attributes this extreme heating to dust ejected into the atmosphere.
Chicxulub refers to a vast crater buried beneath the Yucatán Peninsula in Mexico. It formed when an asteroid struck Earth about 66 million years ago. This event is considered the main cause of the extinction of non-avian dinosaurs.
Illustration image Pixabay
The collision vaporized rocks and expelled huge amounts of debris. Some of this material later condensed into small spherules. Their fall through the atmosphere generated heat, a mechanism already considered to explain widespread fires that occurred at that time.
New simulations add an important element: a thick layer of dust would have retained this energy. It would have then acted as an insulator around the planet. According to calculations, the heat received on the ground would have been 3.5 times more intense than with spherules alone.
This increase would have been enough to spontaneously ignite many forests. The temperatures would also have directly threatened exposed animals. Species that took refuge underground or in shallow waters would have benefited from better protection.
This scenario places a major part of the catastrophe within the first hours after the impact. It complements the effects of earthquakes, tsunamis, and ejecta.
The dust would then have produced the opposite effect. By blocking sunlight for several years, it would have cooled the planet and disrupted photosynthesis for a long time. The same cloud would thus have participated in two successive phases: a brief extreme heating, then a prolonged impact winter. Ecosystems would have suffered these shocks without a recovery period.
This study reinforces the idea of a very rapid terrestrial mortality after Chicxulub. It does not, however, close the debate on the global extent of fires and their exact role in the extinction.