Study provides new evidence ancient asteroid caused global firestorm on Earth

Mar 27, 2013
A new CU-Boulder study shows that an asteroid believed to have smacked Earth some 66 million years ago likely caused a global firestorm that led to extensive plant and animal extinctions. Credit: NASA/JPL

A new look at conditions after a Manhattan-sized asteroid slammed into a region of Mexico in the dinosaur days indicates the event could have triggered a global firestorm that would have burned every twig, bush and tree on Earth and led to the extinction of 80 percent of all Earth's species, says a new University of Colorado Boulder study.

Led by Douglas Robertson of the Cooperative Institute for Research in Environmental Sciences, or CIRES, the team used models that show the collision would have vaporized huge amounts of rock that were then blown high above Earth's atmosphere. The re-entering ejected material would have heated the enough to glow red for several hours at roughly 2,700 degrees Fahrenheit—about the temperature of an oven broiler element—killing every living thing not sheltered underground or underwater.

The CU-led team developed an alternate explanation for the fact that there is little charcoal found at the Cretaceous-, or K-Pg, boundary some 66 million years ago when the asteroid struck Earth and the cataclysmic fires are believed to have occurred. The CU researchers found that similar studies had corrected their data for changing sedimentation rates. When the charcoal data were corrected for the same changing sedimentation rates they show an excess of charcoal, not a deficiency, Robertson said.

"Our data show the conditions back then are consistent with widespread fires across the planet," said Robertson, a research scientist at CIRES, which is a joint institute of CU-Boulder and the . "Those conditions resulted in 100 percent for about 80 percent of all life on Earth."

A paper on the subject was published online this week in the Journal of Geophysical Research-Biogeosciences, a publication of the American Geophysical Union. Co-authors on the study include CIRES Interim Director William Lewis, CU Professor Brian Toon of the atmospheric and oceanic sciences department and the Laboratory for Atmospheric and Space Physics and Peter Sheehan of the Milwaukee Public Museum in Wisconsin.

Geological evidence indicates the asteroid collided with Earth about 66 million years ago and carved the Chicxulub crater in Mexico's Yucatan Peninsula that is more than 110 miles in diameter. In 2010, experts from 33 institutions worldwide issued a report that concluded the impact at Chicxulub triggered mass extinctions, including dinosaurs, at the K-Pg boundary.

The conditions leading to the global firestorm were set up by the vaporization of rock following the impact, which condensed into sand-grain-sized spheres as they rose above the atmosphere. As the ejected material re-entered Earth's atmosphere, it dumped enough heat in the upper atmosphere to trigger an infrared "heat pulse" so hot it caused the sky to glow red for several hours, even though part of the radiation was blocked from Earth by the falling material, he said.

But there was enough infrared radiation from the upper atmosphere that reached Earth's surface to create searing conditions that likely ignited tinder, including dead leaves and pine needles. If a person was on Earth back then, it would have been like sitting in a broiler oven for two or three hours, said Robertson.

The amount of energy created by the infrared radiation the day of the asteroid-Earth collision is mind-boggling, said Robertson. "It's likely that the total amount of infrared heat was equal to a 1 megaton bomb exploding every four miles over the entire Earth."

A 1-megaton hydrogen bomb has about the same explosive power as 80 Hiroshima-type nuclear bombs, he said. The asteroid-Earth collision is thought to have generated about 100 million megatons of energy, said Robertson.

Some researchers have suggested that a layer of soot found at the K-Pg boundary layer roughly 66 million years ago was created by the impact itself. But Robertson and his colleagues calculated that the amount of soot was too high to have been created during the massive impact event and was consistent with the amount that would be expected from global fires.

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User comments : 12

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hemitite
1 / 5 (1) Mar 27, 2013
It could be that some species could actually have been saved from burning up by the tsunamis caused directly or indirectly by the impact. If some of these organisms could have survived the tsunami, the sea water may have protected them from the intense radiant heat long enough to escape being killed.
jwillis84
1 / 5 (3) Mar 27, 2013

bad day on planet Earth

- anybody for steamed vegetables?
MrVibrating
1 / 5 (1) Mar 27, 2013
Fascinating findings. I hadn't previously heard of this heating mechanism, all the more remarkable for the scale and speed of the cataclysm.
Silverhill
not rated yet Mar 27, 2013
roughly 2,700 degrees Fahrenheit—about the temperature of an oven broiler element
I suppose this is a typo, since it's too high by about 1000°. 2700° is almost enough to melt iron.
Argiod
1 / 5 (3) Mar 27, 2013
roughly 2,700 degrees Fahrenheit—about the temperature of an oven broiler element
I suppose this is a typo, since it's too high by about 1000°. 2700° is almost enough to melt iron.


In fact; though the oven itself only goes to about 500 degrees or so, depending on make and model, the element itself gets much hotter.
mikefiggs
not rated yet Mar 27, 2013
roughly 2,700 degrees Fahrenheit—about the temperature of an oven broiler element
I suppose this is a typo, since it's too high by about 1000°. 2700° is almost enough to melt iron.


The material re-entering was 2700 degrees, not the temp on the ground. The space shuttle gets to 1700 degrees on reentry and thats without an asteroid impact sending it up.
Sinister1811
1.7 / 5 (6) Mar 27, 2013
Which was it? An asteroid as this article claims, or a comet as the following article suggests.

http://phys.org/n...ter.html
Silverhill
not rated yet Mar 28, 2013
The material re-entering was 2700 degrees
Aha--I should have said that the temperature of the oven element was mis-stated, not the temperature of the infalling material.
dschlink
5 / 5 (1) Mar 28, 2013
I suspect there were a large number of earthquakes and increased volcanic activity as well. You can't smack a planet that hard without flexing the crust.
mikefiggs
not rated yet Mar 28, 2013
The material re-entering was 2700 degrees
Aha--I should have said that the temperature of the oven element was mis-stated, not the temperature of the infalling material.


LOL gotcha and I agree most nickel-chromium heating elements would melt at that temp but I still have to say a quartz-tungsten heating element can operate at 2500 to 3500 degrees fahrenheit normally. So I guess the question becomes who broils with infrared unless its an industrial kitchen. I would stick with a glass melting analogy for simple imagery with accuracy.
nebeeseer
1 / 5 (1) Mar 31, 2013
Sorry doesn't fit the Strata formation. The K-Pg boundary has high levels of Iridium...not naturally occurring on Earth. For this much Iridium to be deposited everywhere across the earth except New Jersey...yes New Jersey is exempt..Ha. Iridium is produced from the intense heat of an atomic blast. An atomic blast would have had to happen simultaneously everywhere on earth. Manhattan is big but not everywhere.
I am a biblical creationist.
Gen. 1:1-27? explains what we see.Pre-Adamic creation Lucifer and his angels populated the earth Is. 14 Ezk. 28 included dinosaurs ect. the earth was destroyed and (all) living things on it! Fossil record bares this out. THe earth was recreated with what we see today.
Any wisdom without a biblical base..... fairy tails for adults....don't hold water. <3
Silverhill
5 / 5 (1) Apr 01, 2013
Iridium does naturally occur on Earth, just not in great quantities. (Unless you meant that high iridium levels are not naturally occurring; that much is correct.)

Iridium is *not* produced simply by thermal effects of nuclear detonations. Some nuclei might be formed as fission fragments, but very little. Most fission fragments are lighter nuclei (such as barium and krypton).

The fossil record does *not* bear [note spelling] out the simultaneity of dinosaurs and modern life forms.

Note: Biblical creationists tend to get short shrift here, because this is a site for science, not fairy tales [note spelling].

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