Asteroid impacts have changed Earth’s landscape time and time again. Some impacts caused great change to occur, like the Chicxulub Impactor, which led to the mass extinction of dinosaurs around 65 million years ago. While an impact like this caused severe changes to the climate and ended the lines of most non-avian dinosaurs, a new study published in Communications Earth & Environment found that massive asteroid hits may not have changed the planet’s climate in the long term.
After analyzing tiny fossilized sea creatures, a research team from University College London (UCL) found that large asteroid impacts didn’t change the planet’s climate in the 150,000 years after impact. This led the team to believe that not all large asteroid impacts could lead to climate-changing events.
Major Craters on Earth
To garner the results of this study, the research team looked at the impacts of two major asteroids from the late Eocene epoch (about 38 million years to 33 million years ago). One created the 60-mile-wide Popigai crater in Siberia, Russia, and the other created the 25-mile-to-55-mile-wide crater in the Chesapeake Bay in the U.S. These craters are the fourth and fifth largest on Earth.
According to the study, the asteroid that created the Popigai crater was about 3 miles to 5 miles wide and could have been as wide as Mount Everest, while the other asteroid was about 2 miles to 3 miles wide. For comparison, the asteroid that caused the Chicxulub crater was about 6 miles in diameter.
The team believes these two asteroids struck Earth around 25,000 years apart and did not cause waves of long-lasting environmental change.
Learn More: Large Meteor Impacts Can Cause Extinction, But Also May Be Beneficial For Life
The Asteroid Impact
(Credit: Natalie Cheng / Bridget Wade)
Microscope image of silica droplets, or microspherules, found in the rock, this time cropped to be a landscape image and with a plain black background.
While analyzing the carbon and oxygen isotopes in small fossilized shelled creatures called foraminifera, the team compared two types of foraminifera, one that lived on the ocean floor — benthic foraminifera — and one that lived closer to the surface — planktonic foraminifera. The fossils were about 3.5 million years to 3.9 million years old and were found in the Gulf of Mexico during an excavation by the Deep Sea Drilling Project.
With over 1500 specimens to examine, the researchers determined the ocean’s temperature during its lifetime.
“What is remarkable about our results is that there was no real change following the impacts. We expected the isotopes to shift in one direction or another, indicating warmer or cooler waters, but this did not happen. These large asteroid impacts occurred, and over the long term, our planet seemed to carry on as usual,” said Bridget Wade, a professor of Earth Sciences at UCL and co-author of this study, in a press release.
“However, our study would not have picked up shorter-term changes over tens or hundreds of years, as the samples were every 11,000 years. Over a human time scale, these asteroid impacts would be a disaster. They would create a massive shockwave and tsunami, there would be widespread fires, and large amounts of dust would be sent into the air, blocking out sunlight,” Wade continued in a press release.
The Chicxulub asteroid’s impacts on the Earth’s climate would have about a 25-year time scale.
Read More: Scientists Predict Next 1,000 Years of Asteroid Impacts — Are We Safe?
Short Term Change
During the study, the team also found evidence of other smaller asteroids hitting Earth during the late Eocene. Some of the asteroids appeared to have hit in the form of “thousands of tiny droplets of glass, or silica.” The silica likely vaporized from the heat of the asteroid then formed into solid droplets and fell back to Earth.
“Given that the Chicxulub impact likely led to a major extinction event, we were curious to investigate whether what appeared as a series of sizeable asteroid impacts during the Eocene also caused long-lasting climate changes. We were surprised to discover that there were no significant climate responses to these impacts,” said Natalie Cheng, an MSc Geosciences graduate and co-author of the study, in a press release.
“It was fascinating to read Earth’s climate history from the chemistry preserved in microfossils. It was especially interesting to work with our selection of foraminifera species and discover beautiful specimens of microspherules along the way,” said Cheng.
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A graduate of UW-Whitewater, Monica Cull wrote for several organizations, including one that focused on bees and the natural world, before coming to Discover Magazine. Her current work also appears on her travel blog and Common State Magazine. Her love of science came from watching PBS shows as a kid with her mom and spending too much time binging Doctor Who.
