Scientists are continuing to learn new things about the asteroid that wiped out the dinosaurs—and three-quarters of Earth’s other species—66 million years ago. According to research published in the journal Nature Geoscience on Monday, the asteroid’s impact wasn’t just felt on Earth’s land and in its waters. It was also detrimental to the planet’s atmosphere, which was inundated with roughly 2,000 gigatonnes of dust.
Most people familiar with the dinosaurs’ rapid demise know about the infamous asteroid that struck Mexico’s Yucatán Peninsula at the end of the Cretaceous Period. We’ve been aware for a while now of the domino effect that followed: the shaking of the continental plate, the tsunamis, the wildfires, and so on. But these “on the ground” effects weren’t all that contributed to the deaths of countless species. Planetary scientists in Belgium, the Netherlands, the United Kingdom, and the United States say the asteroid’s impact sent dust and other debris into the atmosphere. These dust clouds blocked out so much sunlight that they had their own downstream effects, resulting in what the researchers call “catastrophic collapse.”
The team based their research on preserved sediment from the impact, which archaeologists previously found at a North Dakota paleontological site. The dust was relatively fine, with particles ranging from 0.8 to 8.0 micrometers in diameter, and is thought to have formed when the asteroid made contact with the granite and gneiss rock in the Yucatán Peninsula. Using paleoclimate simulations, the researchers measured how long the dust might have remained in the atmosphere, as well as how the clouds might have impacted the goings-on occurring on Earth’s surface.
They found that the impact-induced dust clouds likely made Earth’s atmosphere opaque for two years, making it virtually impossible for plants to perform photosynthesis. Even after light began to shine through again, the dust remained for another 13 years, resulting in a total global average surface temperature decline of 15 degrees Celsius (59 degrees Fahrenheit). As one can imagine, this was a devastating shift for the dinosaurs, plants, fish, mammals, and other species that weren’t heavily disrupted by the asteroid’s more immediate impacts. Even creatures capable of surviving the asteroid’s “impact winter” eventually died after major components of their diet went extinct.
Complete recovery—meaning a return to pre-impact temperatures—took about 20 years. That might not sound like a lot of time when you’re talking about an event millions of years ago, but it is plenty of time for plant and animal species to disappear.
