A group of researchers, led by geochronologist Timmons Erickson of the Johnson Space Center, analyzed Yarrabubba crater, an impact crater located in Western Australia. By analyzing the rocks, the researchers showed that it is a crater caused by the impact of an asteroid that occurred 2,229 billion years ago.
This is a period that coincides with the end of a deep phase of freezing of the planet known as “Snowball Earth.” Erickson and colleagues in the team do not believe it is a casual connection: the impact of the asteroid itself could have helped the Earth to thaw.
The impact would vaporize the thick slabs of ice on the earth’s surface and help spread relatively warm steam into the stratosphere. This, in turn, would have caused a powerful greenhouse effect and therefore the thawing of the entire globe.
“The temporal coincidence is surprising,” reports Eva Stüeken, a geobiologist at the University of St. Andrews, in a speech on the Science website about this theory. The same researcher, however, shows some doubts. The Yarrabubba impact crater is less than 1/3 wide than that left by the asteroid that caused the dinosaurs to extinguish 66 million years ago.
The researcher, therefore, believes that the impact of Yarrabubba could not have had such a profound effect on a global level.
Erickson and colleagues believe however that the impact of Yarrabubba has played some role in the global thaw. Maybe it was helpful acting together with the supposed volcanic eruptions that are believed to have caused carbon dioxide to be released into the air, causing global warming of the planet and therefore its thawing.
Precisely for this reason, they have created a computer model of the impact of a 5 miles wide asteroid that hits an ice cap with a thickness between 2 and 5 miles. The simulation showed that the impact can cause the spread of dust for thousands of kilometers, darkening the ice and therefore improving its ability to absorb heat.
Furthermore, such an impact can send hundreds of billions of tons of steam into the stratosphere, which would help the atmosphere trap heat.
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