May 21, 2013
Climate Change Due To Meteorite Caused Extinction Of The Woolly Mammoth
Brett Smith for redOrbit.com - Your Universe Online
We humans have often blamed ourselves for the extinction of the woolly mammoth, but a new study from a large team of international researchers has found evidence of a large meteorite breaking apart in the atmosphere about 13,000 years ago — around the time when the prehistoric pachyderms died out.
By studying sediment layers from 18 archaeological sites around the world, the team found tiny spheres of carbon they say are telltale signs of multiple impacts and meteorites' mid-air explosions, according to their study in the Proceedings of the National Academy of Sciences (PNAS).
These tiny bits of carbon, called spherules, are formed when substances burn at extremely high temperatures. According to the study, the samples that were collected across four continents represent an estimated 10 million metric tons of material and could only have been formed by the combustion of rock on a massive scale.
“We know something came close enough to Earth and it was hot enough that it melted rock — that´s what these carbon spherules are,” said co-author Kenneth Tankersley, an assistant professor of anthropology and geology at the University of Cincinnati (UC). “In order to create this type of evidence that we see around the world, it was big.”
Tankersly compared just such an event with the 1883 volcanic explosion on Krakatoa in Indonesia.
“When Krakatoa blew its stack, Cincinnati had no summer,” he said. “Imagine winter all year-round. That´s just one little volcano blowing its top.”
After an event of this magnitude, the researchers said toxic gas would have poisoned the air and blocked out the sun — causing global temperatures to drop. The rapid climate change would have forced the existing plant and animal life into two groups: “winners” and “losers”.
Those that were able to could relocate to a more hospitable climate. Other species may have adjusted their way of living to compensate for their new ecosystem. Some species, like the mammoth, simply went extinct, according to the scientists.
“Whatever this was, it did not cause the extinctions,” Tankersley said. “Rather, this likely caused climate change. And climate change forced this scenario: You can move, downsize or you can go extinct.”
The Cincinnati scientist said that type of global climate change does have some resonance in these modern times.
“Whether we want to admit it or not, we´re living right now in a period of very rapid and profound global climate change. We´re also living in a time of mass extinction,” Tankersley said. “So I would argue that a lot of the lessons for surviving climate change are actually in the past.”
Tankersley also warned about the possibility of another cosmic event that could repeat the events of 13,000 years ago.
“One additional catastrophic change that we often fail to think about — and it´s beyond our control — is something from outer space,” Tankersley said in a statement. “It´s a reminder of how fragile we are.”
“Imagine an explosion that happened today that went across four continents,” he said. “The human species would go on. But it would be different. It would be a game changer.”