A cosmic impact may have set off massive and instantaneous warming on Earth about 56 million years ago, a new study in New York has revealed.
Researchers from Rensselaer Polytechnic Institute have found physical evidence that a giant comet may have crashed into our planet and triggered the warming event known as Paleocene-Eocene Thermal Maximum (PETM).
Studying such an event is important because it offers the best analogs to modern global warming, scientists said.
Finding Clues
During PETM, thousands of gigatons of carbon dioxide accumulated into the atmosphere, causing the global temperature to rise by 8 degrees Celsius (14 degrees Fahrenheit).
At that time, billions of shelled microorganisms died, rock layers contained unusual ratios of carbon isotopes and Arctic sediment cores had no trace of ice.
But how did researchers figure out the link between the warming event and the comet strike?
The clues came in the form of small glass spheres found inside rock core samples from New Jersey and Bermuda, which are called "microtektites."
These glass spheres or spherules are believed to be leftovers or debris that the giant comet ejected when it slammed into Earth.
Morgan Schaller, one of the study researchers and an assistant professor at Rensselaer, says the discovery suggests that there was a cosmic impact around the same time the rock samples were deposited.
"[A] space rock hit the planet," he says.
Schaller and his colleagues were searching for the fossils of a tiny organism known as Foraminifera when he noticed a microtektite in the sediment he was investigating.
Afterwards, they began to search for more and discovered as many as three microtektites per gram of sediment. Schaller says the discovery was completely accidental.
How The Impact Triggered Ancient Climate Change
The coincidence of the cosmic impact with a major warming event has been quite baffling for scientists, but the physical evidence may help support the timing.
Schaller assumes that the event may have possibly triggered intense magnitude 10 earthquakes and released methane stored deep within the ocean into the atmosphere.
The event may have also caused super active volcanoes to erupt, producing large quantities of carbon dioxide.
Meanwhile, Mark Boslough, a physicist from Sandia National Laboratories and who was not involved in the research, says the PETM is a major event in the history of Earth and the sediment discovery may be major if it "holds up."
"It provides a big clue in the chain of discovery that we need to solve that mystery," says Boslough.
Details of the new study are published in the journal Science.
