K-Pg mass extinction heat and wildfires worsened by fine dust (free pdf)
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Ben Creisler
Jul 28, 2026, 2:51:47 PM (9 days ago) Jul 28
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Ben Creisler
There has been much debate about exactly how the asteroid impact caused the mass extinction that ended the reign of the dinosaurs. In this study, we take another look at the idea that extreme heat and widespread fires played a major role in killing land-based life. We show that material ejected by the impact flew around the entire planet. As this material entered Earth's atmosphere, glassy beads called spherules and vapor separated from each other. Evidence from rock layers dating to this time shows that much of the hot vapor later cooled and turned into large amounts of fine dust. When the spherules fell back through the atmosphere and slowed down they generated heat. The abundant fine dust greatly increased the amount of heat reaching the surface of the Earth. This extra heat would have caused intense heating and fires across the land, suggesting that extreme heat was a major cause of death for many land-based organisms.
News
Dinosaur-killing asteroid also created a dust cloud that insulated Earth, ‘charbroiling’ Cretaceous creatures
A new paper:
Free pdf:
Brandon C. Johnson, Alexandria V. Johnson, Shigeru Wakita & Douglas S. Robertson (2026)
Brandon C. Johnson, Alexandria V. Johnson, Shigeru Wakita & Douglas S. Robertson (2026)
Heat and Wildfires During the K-Pg Mass Extinction Enhanced by Fine Dust
Journal of Geophysical Research: Biogeosciences 131(7): e2026JG009837
doi: https://doi.org/10.1029/2026JG009837
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2026JG009837
Free pdf:
https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2026JG009837
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.
Plain Language Summary
Journal of Geophysical Research: Biogeosciences 131(7): e2026JG009837
doi: https://doi.org/10.1029/2026JG009837
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2026JG009837
Free pdf:
https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2026JG009837
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.
Plain Language Summary
There has been much debate about exactly how the asteroid impact caused the mass extinction that ended the reign of the dinosaurs. In this study, we take another look at the idea that extreme heat and widespread fires played a major role in killing land-based life. We show that material ejected by the impact flew around the entire planet. As this material entered Earth's atmosphere, glassy beads called spherules and vapor separated from each other. Evidence from rock layers dating to this time shows that much of the hot vapor later cooled and turned into large amounts of fine dust. When the spherules fell back through the atmosphere and slowed down they generated heat. The abundant fine dust greatly increased the amount of heat reaching the surface of the Earth. This extra heat would have caused intense heating and fires across the land, suggesting that extreme heat was a major cause of death for many land-based organisms.
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News
Dinosaur-killing asteroid also created a dust cloud that insulated Earth, ‘charbroiling’ Cretaceous creatures
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