Scientists have revealed new details about the impact of a massive asteroid that hit the US roughly 35 million years ago.
The asteroid, between three and five miles wide, created a giant 25-mile-wide crater in what now lies beneath Chesapeake Bay, with the center located at the southern end of Northampton County near Cape Charles, Virginia.
While slightly smaller than the event that killed the dinosaurs 66 million years ago, researchers expected it to alter Earth’s global climate similarly.
Instead, they found ‘our planet seemed to carry on as usual,’ according to study co-author Bridget Wade with University College London (UCL).
What’s more, the researchers found another giant asteroid collided with what is now Russia some 25,000 years prior and only disrupted Earth’s climate for a brief period.
That impact left a 60-mile-wide crater – known today as the Popigai crater – in northern Siberia.
These two asteroid strikes formed the fourth and fifth largest known craters on Earth, and yet, they did not trigger any measurable climate changes over the following 150,000 years, the researchers concluded.
‘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,’ Wade explained.
‘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.’
Roughly 35 million years ago, an enormous asteroid slammed into the ocean off the eastern coast the North American continent, but didn’t cause climactic changes (STOCK)
The asteroid, between three and five miles wide, created a giant 25-mile crater in what now lies beneath Chesapeake Bay, with the center located at the southern end of Northampton County near Cape Charles, Virginia
Evidence of the asteroid impacts were found in tiny droplets of silica, which appeared like small balls of glass.
The formations were created by the intense heat released as the asteroid impacts vaporized rocks on.
The team inferred what Earth’s climate looked like after the asteroid strikes by analyzing carbon and oxygen isotopes in more than 1,500 fossils of shelled, single-celled organisms called foraminifera.
These tiny sea creatures lived near the ocean surface or on the sea floor between 35.5 and 35.9 million years ago, and served as a record of how warm Earth’s oceans were at that time.
The fossils were found embedded within 10 feet of a rock core drilled from underneath the Gulf of Mexico by the scientific Deep Sea Drilling Project.
The researchers found shifts in isotopes 100,000 years prior to the two asteroid impacts that suggested the ocean surface warmed 3.6 degrees Fahrenheit, and the deep ocean cooled 1.8 degrees Fahrenheit.
But they did not find evidence of any climactic shifts around the time of the impacts or afterwards.
Another giant asteroid that collided with what is now Russia some 25,000 years prior similarly did not disrupt Earth’s climate for more than a brief period
‘What is remarkable about our results is that there was no real change following the impacts,’ Wade said in the statement.
‘We expected the isotopes to shift in one direction or another, indicating warmer or cooler waters, but this did not happen.’
The researchers published their findings in the journal Communications Earth & Environment today.
The isotope samples collected were over intervals of 11,000 years, and therefore do not reflect the short-term affects of these massive asteroid impacts, which would have been a ‘disaster’ over a human time scale, Wade said.
The Chicxulub impact, for example, caused a shift in climate on a much smaller timescale of less than 25 years. But it was so extreme that it triggered the extinction of the dinosaurs.
‘So we still need to know what is coming and fund missions to prevent future collisions,’ Wade said.
NASA’s Planetary Defense Coordination Office (PDCO) is developing strategies and protocols to prevent a catastrophic asteroid strike.
Evidence of the asteroid impacts were found in tiny droplets of silica, which appeared like small balls of glass. The formations were created by the intense heat released as the asteroid impacts vaporized rocks on
The PDCO’s primary mission is finding, tracking and better understanding asteroids that could pose a threat to Earth. But it also launched the Double Asteroid Redirection Test (DART) mission in November 2021.
This mission rammed a spacecraft into the near-Earth asteroid Dimorphos to alter its trajectory – a strategy NASA could one day use to save the planet from an oncoming asteroid.
Even though Wade and Cheng’s study did note capture the more immediate affects of the strikes, they did create a more precise timeline of climactic change, as previous studies used fossils samples over intervals longer than 11,000 years.
What’s more, using fossils that lived at different ocean depths provided a more complete picture of how the oceans responded to the asteroid strikes.
‘It was fascinating to read Earth’s climate history from the chemistry preserved in microfossils,’ Cheng said.
