Asteroid strike caused global firestorm that incinerated the dinosaurs
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- Brandon Johnson at Purdue University led simulations showing the 10–15 km Chicxulub asteroid vaporized over 1,000 cubic kilometers of rock — about five times more material than earlier estimates — within roughly one second of impact.
- The vapor plume was blasted tens of thousands of kilometers into space and re-condensed into 1.6 trillion tonnes of dust that blanketed the planet and trapped heat, the study published in the Journal of Geophysical Research Biogeosciences found.
- Heavier glassy, metallic beads called spherules re-entered the atmosphere over hours, producing an approximately hour-long pulse of thermal radiation intense enough to ignite grass, pine needles, and potentially whole trees.
- Cretaceous animals received 17 times the thermal radiation dose that is 100% lethal to humans, according to Johnson — enough, he says, to kill even thick-skinned dinosaurs.
- Craig O'Neill at Queensland University of Technology called the resulting surface heating "history's largest barbecue" but stressed the picture is incomplete: marine extinctions of mosasaurs and ammonites are better explained by the sun-blocking nuclear winter, not the thermal pulse.
- O'Neill framed mass extinctions as a "cascading system of failures" rather than a single murder weapon, arguing the firestorm and the nuclear winter each drove different species toward extinction.
Why it matters: The study overturns the prevailing view that the dinosaurs' killer was primarily a years-long nuclear winter from sun-blocking dust, showing the impact's heat pulse alone could have ignited forests on a global scale within an hour — forcing paleontologists to re-weight which extinction mechanism killed which species.
