Throughout Earth’s history, the planet has been struck by multiple asteroids, some so large, like the Chicxulub Impactor, that Earth’s climate was altered to the point of a mass extinction event.
However, after analyzing tiny fossilized sea creatures, a recent study in Communications Earth & Environment found that two massive asteroid hits about 35.65 million years ago did not cause a change to Earth’s climate in the long term.
Creating Major Craters
For this study, a research team from University College London (UCL) looked at the impacts of two major asteroids from the late Eocene epoch (about 38 million to 33 million years ago).
One created a 25- to 55-mile-wide crater in the Chesapeake Bay, the fifth largest crater on Earth. The other created the 60-mile-wide Popigai crater in Siberia, Russia — the fourth largest on Earth.
According to the study, the Popigai crater asteroid was about 3 to 5 miles wide — possibly the size of Mount Everest — while the other asteroid was about 2 to 3 miles wide. In comparison, the Chicxulub Impactor was about 6 miles wide.
The asteroids likely struck Earth around 25,000 years apart and did not cause waves of long-lasting environmental change.
Read More: A Meteorite That Hit Scotland a Billion Years Ago Changed Life on Earth
Clues in the Fossils
To determine the impact that these asteroids had on the climate at the time, the research team analyzed the carbon and oxygen isotopes in small fossilized shelled creatures called foraminifera.
The research team compared two types of foraminifera, one from the ocean floor — benthic foraminifera — and one that lived closer to the surface — planktonic foraminifera. The Deep Sea Drilling Project found the 3.5 million to 3.9 million-year-old fossils in the Gulf of Mexico during an excavation.
Thanks to the 1,500 specimens, the researchers determined the ocean's temperature during their 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 had a 25-year time scale.
Smaller Asteroid Impacts
According to the research team, during the study, they 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 sizable 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.
This article is a republished version of this previously published article here.
Read More: A Hydrothermal System May Have Helped Life Recover After Chicxulub Impactor
Article Sources
Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:
Communications Earth & Environment. No paleoclimatic anomalies are associated with the late Eocene extraterrestrial impact event.s
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.
