New research, led by scientists at Purdue University, reveals that microscopic dust generated by the asteroid impact that hit Earth about 66 million years ago may have been the main cause of the mass extinction of the dinosaurs. Published on August 4, 2026, the study suggests that these particles, released into the atmosphere, acted as a “thermal blanket”, preventing heat dissipation and causing global overheating. This phenomenon would have triggered large-scale forest fires, decimating approximately 75% of the planet’s living species.
How heat was retained after impact
The asteroid, of dimensions comparable to those of Mount Everest, collided with the Yucatán Peninsula, in Mexico, forming the vast Chicxulub crater. The violent collision released a colossal amount of vaporized material into the Earth’s atmosphere. According to Brandon Johnson, professor in the Department of Earth, Atmospheric and Planetary Sciences at Purdue University and lead author of the study, this enormous kinetic energy was converted into heat that spread across the planet.
Previous studies by Johnson and his former advisor Jay Melosh had already shown that the impact vaporized more than a thousand cubic kilometers of rocks, soil, plants and animals. When cooled in the upper atmosphere, this material condensed into small drops of rock, called spherules, which, upon returning to Earth, heated up due to friction with the atmosphere and released additional heat.
The difference between spherules and fatal dust
Paleontologists have found fossilized spherules in several parts of the world, including at a site in North Dakota, where they were preserved in the gills of paddlefish. Researchers estimate that these animals died on the same day of impact.
However, the new research differentiates the fate of the material from the asteroid itself. Instead of forming spherules, it turned into a cloud of extremely fine dust. With particles of around 2.5 micrometers in diameter, this dust has spread globally, functioning as a thermal insulator. This distinction is crucial to understanding the intensity of the catastrophe.
The “oven” effect that wiped out the dinosaurs
Brandon Johnson describes that this layer of dust trapped thermal radiation. He compares the situation to that of a “pot” where the surface of the Earth and everything on it was “roasted on coals”. The heat could not escape into space, continually returning to the surface.
The researcher claims that the blocking of thermal radiation by the fine dust cloud drastically raised the temperature. He calculates that animals from the Cretaceous period received a dose of thermal radiation 17 times higher than that considered 100% lethal for humans. This intense heat was enough to:
- Set grasses and pine needles on fire
- Burn lichens
- Possibly cause direct combustion of wood
Johnson emphasizes that while the initial impact and fireball were severe, what turned the event into a global extinction was the planetary ejection of this vaporized material and the resulting heat retention.
Organisms that managed to protect themselves from extreme heat
Faced with such adversity, only organisms that had means of protection against extreme heat had any chance of survival. Among them, those that stand out are:
- They lived underground, in holes and holes
- They took shelter underwater, in rivers and oceans
- They occupied other environments that isolated them from the hot atmosphere
Alexandria Johnson, an assistant professor in the Department of Earth, Atmospheric and Planetary Sciences at Purdue University who analyzed the physical properties of the dust particles, explained that the cloud layer was so dense that virtually all of the heat from the falling spherules was trapped near the surface. According to her, “the dust essentially acted like the lid of a pan”, intensifying mortality on a large scale.
Similarity to smoke from current fires and gloomy scenery
The layer of dust, according to the study, could have remained in the atmosphere for years or even decades. In addition to worsening the heat, the particles would pose an ongoing risk to organisms that might survive.
Alexandria Johnson makes an analogy with the dust produced by impacts and smoke particles resulting from current forest fires. The 2.5 micrometer particles that were studied are the same size as smoke from contemporary wildfires. They can penetrate the lungs and bloodstream, causing public health problems.
The post-impact scenario described by researchers is one of almost complete darkness, with clouds blocking daylight. The environment would be more like “hell than Venus”, with only a red glow visible from forest fires.
