A new study suggests that the asteroid impact that wiped out the dinosaurs may have been even more deadly than scientists once thought.
Researchers now believe that a huge cloud of dust left behind after the impact trapped heat in Earth’s atmosphere, creating temperatures high enough to ignite wildfires around the world and kill many animals within just a few hours.
About 66 million years ago, a giant asteroid about 10 kilometers (6 miles) wide slammed into what is now Mexico’s Yucatán Peninsula, creating the Chicxulub crater.
This event marked the end of the dinosaurs and about 75% of all species on Earth.
While scientists have long agreed that the impact caused the mass extinction, they have debated exactly how it happened.
The new research, published in the Journal of Geophysical Research: Biogeosciences, points to an intense heat wave that may have swept across the planet almost immediately after the collision.
When the asteroid struck Earth, the enormous force instantly vaporized huge amounts of rock. Some of this material cooled into tiny glass-like droplets called spherules.
These particles were thrown high into the atmosphere before falling back toward Earth like countless tiny meteorites. As they rushed through the atmosphere, they generated intense heat through friction.
Earlier studies suggested that the falling spherules created enough heat to seriously burn animals exposed on the surface but not enough to start widespread forest fires.
However, lead author Brandon Johnson, a planetary scientist at Purdue University, became interested in another part of the story after researchers discovered evidence in 2023 for an extremely fine layer of dust left behind by the impact.
Johnson and his team combined computer simulations with geological evidence to estimate how much fine dust remained in the atmosphere after the collision. Their calculations showed that this dust acted like a giant insulating blanket, trapping heat from the falling spherules and sending it back toward Earth’s surface.
According to the study, this process made surface heating about 3.5 times stronger than previous estimates. Temperatures may have become high enough to ignite forests across much of the world and kill even large animals with thick skin. The researchers suggest that many land-dwelling animals may have died within the first hour or two after the impact.
Ironically, the same dust that trapped heat at first may also have cooled the planet later. Once the fiery debris stopped falling and the fires died down, the thick dust cloud likely blocked sunlight for years or even decades. This would have caused a long-lasting “impact winter,” making it difficult for plants to grow and leaving surviving animals with little food.
Not all scientists are convinced that global fires occurred everywhere. Evidence for widespread wildfires has been found mainly in North America, and researchers are still searching for similar signs in other parts of the world. More geological evidence will be needed to determine whether intense fires or the long, cold impact winter played the biggest role in the mass extinction.
Scientists also hope to learn more about the animals that survived. Understanding why some species lived while the dinosaurs disappeared could help explain how life recovered after one of Earth’s greatest natural disasters.
Source: KSR.
