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Mukul Sharma of Dartmouth College has published a paper saying an asteroid that hit about 13,000 years ago cooled the planet during a warming trend.
The period is known as the Younger Dryas, in which the planet went from warming to cooling for a millennium, CBC reports. During that time, many ice-age animals went extinct and mammals had to forage for plants and berries. Sharma says, “It was an abrupt event when the Earth (was starting) to warm up.”
“Suddenly, the climate changes again to very, very cold conditions and remains so for 1,400 years and then goes back merrily to warming again,” the scientist added.
It’s been hypothesized by some that the cooling period was a result of a giant ice dam made up of receding glaciers receding. This collapse released cold freshwater into oceans, disrupting ocean currents and changing climate trends.
Sharma believes otherwise. Remains from possible meteors have been found before, but not evidence of any actual impact.
Similar theories to Sharma’s have risen before, according to Scientific American. The problem was critics didn’t believe there was any real evidence to prove those theories.
Sharma and company believe they found evidence in minerals from Pennsylvanian soil that would need to be created in temperatures higher than 2,000 C to form. According to them, an impact is the only explanation for that. Sharma stated, “We lucked out.”
The minerals were sent by a Pennsylvania resident, Yvonne Malinowski, who – after watching a documentary on the Younger Dryas – sent some rocks to paleoceanographer James Kennett of the University of California, Santa Barbara. He contacted Sharma.
Studying the minerals in the rocks yielded evidence they came from a 1,000-square-kilometer bit of land in Quebec. Kennett claims, “This is unequivocal evidence for an impact with Earth."
CBC notes that Quebec is known for several impact craters across its land, especially the Manicouagan impact crater – one you can see from space, which is known to be one of the oldest found. Sharma theorizes that the impact crater just hasn’t been found yet.
Others aren’t so sure the evidence proves anything in favor of Sharma’s theory. And Sharma himself admits the evidence doesn’t necessarily point to the meteor creating the cooling trend.
The Younger Dryas “is an interesting event.” He added, “Some would say it’s a freakish event.”
image: Wikimedia Commons