For decades, scientists have debated the cause of the mass extinction that wiped out the dinosaurs and other life 65 million years ago. While the majority of researchers agree that a massive asteroid impact at Chicxulub, Mexico is the culprit, there have been some dissenters. Now, new research is questioning just a portion of the asteroid/Cretaceous-Paleogene extinction scenario. While the scientists involved in the study don’t doubt that such an asteroid impact actually happened, their research shows it is just not possible that vast global firestorms could have ravaged our planet and be the main cause of the extinction.
Researchers from the University of Exeter, University of Edinburgh and Imperial College London recreated the vast energy released from a 15-km wide asteroid slamming into Earth, which occurred around the time that dinosaurs became extinct.
They found that close to the impact site — a 180 km wide crater in Mexico — the heat pulse would have lasted for less than a minute. This intense but short-lived heat, the team says, could not have ignited live plants, challenging the idea that the impact led to global firestorms.
However, they did find that the effects of the impact would actually be worse on the other side of the planet, where less intense but longer periods of heat could have ignited live plant matter.
“By combining computer simulations of the impact with methods from engineering we have been able to recreate the enormous heat of the impact in the laboratory,” said Dr. Claire Belcher from the University of Exeter. “This has shown us that the heat was more likely to severely affect ecosystems a long distance away, such that forests in New Zealand would have had more chance of suffering major wildfires than forests in North America that were close to the impact. This flips our understanding of the effects of the impact on its head and means that palaeontologists may need to look for new clues from fossils found a long way from the impact to better understand the mass extinction event.”
The Cretaceous-Paleogene extinction was one of the biggest in Earth’s history and geologic evidence of the impact has been discovered in rock layers around the world from this time period. Some critics of the asteroid impact theory as a cause of the extinction have pointed to some of the microfossils from the Gulf of Mexico that show the impact occurred well before the extinction and could not have been its primary cause. Others point to volcanism that produced the Deccan traps of India around this time as a possible cause of the extinction.
But multiple models have showed such an impact would have instantly caused devastating shock waves, tsunamis, and the release of large amounts of dust, debris and gases that would have led to a low light levels and a prolonged cooling of Earth’s surface. The darkness and a global winter would have decimated the planet life and the dependent animals.
So while fire and brimstone may not have played a big role in the Cretaceous-Paleogene extinction, there was plenty of destruction and mayhem for the resulting extinction of more than 70% of known species.
Here’s a video from the researchers that shows their findings that close to the impact site, the heat pulse was too short to ignite live plant material.
Their research is published in the Journal of the Geological Society.
Source: University Exeter
I might be wrong but… I understand that these scientists calcultated the heat produced by the impact… and the impact alone. What about the returning rocky stuff, the ejecta? As far as I interpret the global map 65 million years ago there was an atlantic ocean, but much smaller and so this returning stuff adds to the thermal chaos in places further away. Now… once Africa is set ablaze, Europe a kiln… this will add to transform Earth into something like Riddiks Crematoria.
ejecta won’t be traveling at 20 km/s when falling back.
More like 50 meters per sec or about 200 km/h. Terminal velocity of the individual ejecta.
Hmm, if you’re going to use the resulting surf of that, wear proper heat protection, top notch ear plugs and a bucket of water.
Otherwise, be in an airballoon and see the heatwave roll under you while it pushes the airlayers up. Should be quite safe.
I have a really odd theory that is probably just non-relevant, but it seems to me that it is awfully odd that the dinosaurs were so large, and, were they living today, I doubt they could survive. The earth collects mass, a huge amount per year, and given that the dinosaurs walked the earth millions of years ago, is stands to reason that gravity was somewhat weaker than it is now. That would also explain how a pterodactyl could fly. The right size and mass objects hitting the earth could significantly increase the gravitation of the earth. Ok, I am done with my crazy theory . . .
The last time the Earth experienced a significant change in mass was when the Moon was created. It’s not that the Earth doesn’t collect mass every year, it’s just that the additional mass over millions of years is still negligible when compared to the Earth’s overall mass especially when limiting the time scale to when dinosaurs were alive.
How do they determine the increase or decrease of mass over time?
Size increase (and any other body adaptation) is a balanced co-evolution between prey and hunter’s preference for prey and the way it captures it … AND (!!!) interspecie competition.
Sumo wrestling is a sport which uses mass
Basketball prefers length etc.
Only with human sports, there is no penalty if they’re not good at the sport. They can be good at anything else and their children have that freedom of succes as well.
(Ofc. if their dad wants them to be sumo wrestler or else denounces them … that can be a penalty in the long run.)
Yes, a change in surface gravity, not an asteroid or volcanic activity, caused the extinctions. The Gravity Theory of Mass Extinction explains why some dinosaurs reached their gigantic size as well as the primary cause of all 5 mass extinctions. It is able to explain why massive flood basalt volcanism is coincident with these mass extinctions. If you search for a Youtube video of this theory you will get a brief summary.
But who said a firestorm wiped out the dinosaurs? This is a completely new theory for me. The common theory is that the dust and aerosols that the comet strike ejected put a shroud around the planet stopping the sunlight around the Earth for decades. This lowered the temperature drastically and affected vegetation and animals badly.
Add to this that this probably created volcanic eruptions on the other side of the Earth, due to the stress on the mantel, who also spew out of dust and other particles.
Total nonsense there are too many faults in this recreation bad science is worse than a bad guess …….
Maybe someone should tell the dinosaurs.
Oh wait, they’re dead.
More bad science. The firestorm alone has not been postulated as the cause of extinction. I agree with the writer that plenty of post impact disruptions to the climate such as excess NO2, disruption of the ozone layer, aerosols & dust lowering temperatures for years killing plants that starved herbivores, which starved carnivores, etc.
‘splain to me how the ozone layer would be effected by an impact?
The Chicxulub impact was on a carbonate shelf. Gigatons/hundreds of cubic kilometers of CO2 and water vapor were release when the shelf was vaporized. Sun blocked or not, I’d say it got warmer, not colder.
And the facts are we don’t know. All we know is that there was an impact (or two or three. see boltish crater). Before the impact thar be dinosaurs, post impact, not so much.
An impact that size would do a couple of things to the ozone layer. First, The physical disruption of a meteor so large that the tail end would still be in a vacuum when the leading edge struck the ground. This would cause supersonic winds away from the epicenter to stir up all the layers of the atmosphere for thousands of miles in every direction. Most of the ejecta would not have to go through atmosphere on the way out off the planet. And some of the ejecta would be traveling near impact speed when coming down as the atmosphere still would not have reversed it’s course to fill in the whole made by the meteor. The atmosphere itself would have been superheated by this event. The questions are how far the superheating would travel away from the impact is whether we would get firestorm Earth. And is the superheating alone enough to ignite the oxygen in our atmosphere? I’m thinking no to firestorm Earth. (Most likely Firestorm Hemisphere is a given.) And yes to the superheating to ignite oxygen to leave the Earth oxygen poor (but CO2 rich for plant life). Note: Only the smallest of creatures survived which would support my theory. Small creatures use and need less oxygen to survive. And plant life flourished afterwards because of the rich CO2 environment.
I feel like dino myself now…without a planetary protection program. Looks like we can have this conversation AFTER we got our a***s covered.
After seeing Comet Shoemaker/Levy 9’s fragments smack into Jupiter like 10 times.. I realized that the object that hit Southern Mexico at Chixilub might not have been alone? Was it big enough to have a co-orbital? Perhaps this wasn’t a singular catastrophic event and we aren’t seeing the whole picture? Yeah.. maybe the Earth got the old ONE TWO punch? Or even the old ONE TWO THREE FOUR FIVE punch?
try thinking of seconds from disaster or planecrash investigation ….
only now the plane has been rusted to a mere shadow in a layer of ground …
Was it the fire?
Was it the smoke?
Was it even related?
SCIENCE on a shadow in a layer of dirt … just imagine!!
There is some evidence to suggest that the Yucutan impact was one of a series. But there is a layer of soot within the iridium layer, worldwide, and bubbles in amber indicate that the oxygen level in the atmosphere was higher than it is now (helping the pterosaurs to fly), all supporting the idea that big fires were generated locally by the ejecta. Lovelock and Allaby calculated that the groundshock worldwide would have hurled everything movable ten feet in the air, enough to kill the big dinosaurs with multiple fractures, while the small mammals would have bounced and run away to shelter. If it didn’t wipe out the dinosaurs, it really seems that it could have!
This is strange: a worldwide firestorm? That’s not what I keep hearing/reading, and it DOES sound implausible.
I usually see fallout and “foul weather” in the wake of the impact cited as the main culprits… sometimes with some concurrent volcanism added to the mix …
Some scientists have questioned the role of the asteroid impact on the demise of the dinosaurs for many years. Indeed it is likely that the extinction event had more than one cause.
However to say that a meteorite impact rated at 100 million hydrogen bombs could not start a forest fire when every year many wildfires are caused by a single lightning strike (each) is questionable.
In the Observatory we have a sample of the KT layer from Gubbio in Italy. A thin layer of soot can be clearly seen and on it rest tiny orange drops of once molten rock. The KT layer contains a “high” concentration of iridium which is an indicator of a meteorite/asteroid impact. However the main thrust of the research was to demonstrate the far reaching effect of the heat pulse. The effects at a distance are claimed to be greater than those closer to the strike site. This reinforces the theory that a single event could cause a worldwide disaster. We will continue to call our sample a 65 million year old murder weapon!
Roseland Observatory – UK (near Exeter)
When the next one hits it will end all debates.