A new study indicates the Chicxulub asteroid strike 66 million years ago produced a planetary firestorm that incinerated land life worldwide.
The 10- to 15-kilometre-wide asteroid struck what is now the Gulf of Mexico at the end of the Cretaceous period. Simulations by Brandon Johnson of Purdue University and colleagues show the impact vaporised over 1000 cubic kilometres of rock in seconds, sending a plume of vapour into space.
The vapour condensed into 1.6 trillion tonnes of dust and glassy spherules that re-entered the atmosphere hours later. Friction from the returning material created an hour-long pulse of thermal radiation intense enough to ignite vegetation and kill exposed animals.
Johnson stated that Cretaceous animals received 17 times the thermal radiation dose lethal to humans. Craig O’Neill of Queensland University of Technology noted the dust layer trapped heat, turning land surfaces into a global barbecue for about 30 minutes.
The study appears in the Journal of Geophysical Research Biogeosciences. It adds that ocean extinctions were more likely driven by subsequent nuclear-winter effects.