When a massive asteroid struck the Chesapeake Bay on the U.S.'s East Coast about 36 million years ago, it created an enormous impact crater spanning tens of miles but caused surprisingly little long-term harm to the planet, new research shows.
What makes this finding even more remarkable is that 25,000 years prior, another giant asteroid collided with Earth in what is now Russia. That impact left a crater 60 miles wide but similarly failed to disrupt Earth's overall climate for more than a brief period.
According to a study published in Communications Earth & Environment, the two asteroid strikes, which formed the fourth- and fifth-largest known craters on Earth, did not trigger any sustained climate changes over the following 150,000 years.
"We were expecting some kind of climate perturbation, most likely cooling to result from the impacts, so we were surprised to find no climatic response," Bridget Wade, the study's co-author, told Newsweek.
She added in a statement: "These large asteroid impacts occurred and, over the long term, our planet seemed to carry on as usual."
A city-sized meteor slamming into the earth's atmosphere, creating shock waves. When two meteors hit Earth within 25,000 years of each other, neither did much to the long-term climate of the planet, a study found....A city-sized meteor slamming into the earth's atmosphere, creating shock waves. When two meteors hit Earth within 25,000 years of each other, neither did much to the long-term climate of the planet, a study found. solarseven/GettyThe research team analyzed isotopes in the fossils of ancient seafloor creatures from that era. These isotopes, which vary with water temperature, provided a window into the climate of the time.
"The fossils are about the size of a grain of sand (0.5 mm) and we can separate them into different species under the microscope," Wade said.
The results showed astonishing stability in Earth's climate despite the scale of the impacts.
In the short term, however, the consequences for life would have been catastrophic.
The immediate aftermath likely included apocalyptic tsunamis, widespread fires and massive clouds of dust capable of temporarily blocking sunlight.
"Our study would not have picked up shorter-term changes over tens or hundreds of years, as the samples were every 11,000 years," Wade said. "Over a human timescale, these asteroid impacts would be a disaster."
The asteroids themselves were much smaller than their craters—both were less than 5 miles wide—highlighting the force with which they struck the ground.
Evidence of these impacts was found by the team in the form of tiny droplets of silica, created when the heat of an asteroid collision vaporizes rock.
The researchers noted significant temperature shifts in their data—about 3.6 degrees Fahrenheit warming at the ocean surface and 1.8 degrees Fahrenheit cooling in deeper waters—but these changes occurred 100,000 years before the asteroid strikes and were unrelated to the impacts themselves.
Natalie Cheng, another co-author of the study, summarized the unexpected findings: "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."
Do you have a tip on a science story that Newsweek should be covering? Do you have a question about asteroids? Let us know via science@newsweek.com.
