Evidence collected along the New Jersey coastline suggests that the collision of a comet or other extraterrestrial body 55 million years ago coincided with an intense warming period that is the closest comparison to today’s climate change.
The period of warmth, called the Paleocene-Eocene Thermal Maximum (PETM), was preceded by a rapid release of carbon into the atmosphere, with effects lasting for about 200,000 years. The increase in carbon raised the Earth’s temperature by up to 16 degrees Fahrenheit. As a result, the planet was almost ice-free and sea levels rose significantly higher than they are now. It caused a mass extinction for single-cell creatures in the ocean, but animals on land, especially primates, thrived and rapidly evolved by moving toward the poles, where temperatures are lower.
There is still disagreement among scientists as to what triggered the carbon release during that era. Current theory posits that this mysterious release of carbon dioxide came from volcanoes and suggests that the warming may have been abetted by a sudden release of methane from the ocean floor.
But the new study, published yesterday in the journal Science, connects the warming to the impact of the extraterrestrial object.
In New Jersey, researchers found tiny spherical droplets of glass called microtektites, which form from vaporized debris as it flies through the air after an extraterrestrial object hits the Earth. The glass debris was found in samples from the towns of Millville, Wilson Lake and Medford, as well as from one collected from the deep seabed off the coast of Bermuda.
The discovery of the droplets, found in a clay deposit traced to the PETM period, could signal that the area was “ground zero” for an impact, said Dennis Kent, a researcher at Columbia University’s Lamont-Doherty Earth Observatory and a co-author of the study. He said it warmed in a hurry, and the new study suggests where it came from.
If a comet triggered the last period of significant warming as a result of carbon release, Kent said, it can provide information for today’s researchers on climate. If carbon warmed the planet in a matter of years or decades, rather than millennia, it could provide insight into what today’s climate change may bring, he said.
“This could be even more rapid than today, and studying that in more detail could say something about the limit of that climate change compared to today,” he said.
In 2003, Kent first proposed that magnetized clay particles he discovered in New Jersey could be evidence that a comet hitting the Earth led to the PETM. A 2013 study found that the PETM was triggered almost instantaneously, based on carbon isotopes found in the same clay sediment.
The new study does not claim to have located a crater or to prove that the collision of a comet or other extraterrestrial object triggered the PETM. But it does build the body of evidence suggesting a connection, said Morgan Schaller, an assistant professor of earth and environmental sciences at Rensselaer Polytechnic Institute.
“It’s got to be more than coincidental that there’s an impact right at the same time,” he said in a statement. “If the impact was related, it suggests the carbon release was fast.”
Many in the scientific community have rebutted that argument, however. The new study doesn’t prove exactly what triggered the PETM period, Rice University marine geologist Gerald Dickens said. He said there is plenty of evidence that the carbon release took thousands of years. Current theory on the cause of the PETM was that the carbon was released over 5,000 to 20,000 years, not suddenly.
“Finding a few spherules does not change this,” he said.
Other researchers have found evidence that the carbon release during the PETM period was instantaneous.
Regardless of what triggered the PETM period, which profoundly changed the planet, humans are now warming the Earth 10 times faster than it heated up during that era, a study published earlier this year in Nature found. The PETM period saw the highest rates of carbon released in 66 million years, according to the study by University of Hawaii researchers.
Reprinted from ClimateWire with permission from Environment & Energy Publishing, LLC. E&E provides daily coverage of essential energy and environmental news at www.eenews.net. Click here for theoriginal story.
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