Dinosaur-Killing Asteroid Impact Not Followed by Wildfires

Dinosaur-Killing Asteroid Impact Not Followed by Wildfires

29 December 2009

published by news.softpedia.com

Global — For a long time, experts have believed that the asteroid that killed off the dinosaurs was followed, immediately after the impact, by a combustion of the world’s forests. The scientists thought that droplets of molten rock that were formed when the space rock hit heated up the atmosphere by a few degrees for more than 20 minutes, causing trees around the globe to spontaneously catch fire. Now, new evidence seems to suggest that this was not the case,Space reports.

It is widely believed among scientists in the international community that the last extinction event, the disappearance of dinosaurs, was caused by an asteroid hitting the Yucatan Peninsula in Mexico. They believe that the impact created the Chicxulub crater, one of the largest on our planet.

The extinction event, which took place more than 65 million years ago, is generally accepted as the time when the dinosaurs went extinct, and is referred to as the Cretaceous–Tertiary (K-T) boundary.

According to previous models, when the asteroid struck, massive amounts of liquefied rock droplets known as spherules formed. It was proposed that these structures heated the atmosphere considerably while raining down from the sky, and that the sudden increase in temperature would be enough to spark a global wildfire. However, in a new report, scientists present acomputer model that disproves this idea. Published in the latest issue of the respected scientific journal Geology, the model shows that the first incoming wave of spherules might have coalesced into an opaque cloud above the surface.

The new simulation also proposes that the opaque formation, which appeared at an altitude of about 40 miles (70 kilometers), essentially acted as a shield, catching all the spherules raining from above, and preventing them from causing excessive warming. “As more and more spherules are injected into the upper atmosphere, the cloud of settling spherules becomes thicker and denser. So previously entered spherules help to shield the ground of some fraction of the thermal radiation from the subsequently entering spherules,” University of Vienna team member Tamara Goldin explains.

“If you were on the ground, it would feel at the maximum like you’re under a broiler in your oven. It would not be very comfortable, but it would not be instant immolation,” she adds. The expert says that the new model does not disprove the idea that dinosaurs were indeed killed by an asteroid impact. Goldin emphasizes the fact that her research was aimed at understanding whether or not wildfires followed soon after the impact or not.

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