Doubt cast on global firestorm generated by dino-killing asteroid

January 22, 2015, University of Exeter
Fire propagation apparatus recreating the impact induced thermal pulse at the Cretaceous-Palaeogene (K-Pg) boundary. Halogen lamps are delivering the thermal radiation. Credit: University of Exeter

Pioneering new research has debunked the theory that the asteroid that is thought to have led to the extinction of dinosaurs also caused vast global firestorms that ravaged planet Earth.

A team of researchers from the University of Exeter, University of Edinburgh and Imperial College London recreated the immense energy released from an extra-terrestrial collision with Earth that occurred around the time that dinosaurs became extinct. They found that the intense but short-lived heat near the impact site could not have ignited live plants, challenging the idea that the impact led to global firestorms.

These firestorms have previously been considered a major contender in the puzzle to find out what caused the mass extinction of life on Earth 65 million years ago.

The researchers found that close to the impact site, a 200 km wide crater in Mexico, the heat pulse - that would have lasted for less than a minute - was too short to ignite live plant material. However they discovered that the effects of the impact would have been felt as far away as New Zealand where the heat would have been less intense but longer lasting - heating the ground for about seven minutes - long enough to ignite live plant matter.

The experiments were carried out in the laboratory and showed that dry could ignite, but live plants including green pine branches, typically do not.

Dr Claire Belcher from the Earth System Science group in Geography at the University of Exeter said: "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. 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 event."

Plants and animals are generally resistant to localised fire events - animals can hide or hibernate and plants can re-colonise from other areas, implying that wildfires are unlikely to be directly capable of leading to the extinctions. If however some animal communities, particularly large animals, were unable to shelter from the heat, they may have suffered serious losses. It is unclear whether these would have been sufficient to lead to the extinction of species.

Dr Rory Hadden from the University of Edinburgh said: "This is a truly exciting piece of inter-disciplinary research. By working together engineers and geoscientists have tackled a complex, long-standing problem in a novel way. This has allowed a step forward in the debate surrounding the end Cretaceous impact and will help Geoscientists interpret the fossil record and evaluate potential future impacts. In addition, the methods we developed in the laboratory for this research have driven new developments in our current understanding of how materials behave in fires particularly at the wildland-urban-interface, meaning that we have been able to answer questions relating to both ancient mass extinctions at the same time as developing understanding of the impact of wildfires in urban areas today."

The results of the study are published in the Journal of the Geological Society.

Explore further: Dinosaurs doing well before asteroid impact

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4.4 / 5 (9) Jan 22, 2015
Dinosaurs not extinct. See them everyday in garden. They fly over from the park. Eat them, especially at Xmas. Have their eggs as omlettes etc. or in cakes. They evolved into birds.
5 / 5 (7) Jan 22, 2015
A number of gaps appear in this model:

1. Was this a single-body impact?

2. What time of year? Dry season or wet? Flower or seed time?

3. The extent of fire would be dependent upon how much dry vegetation was present, and whether it would be sufficient to initiate and sustain burning of green vegetation.

4. Wind and other atmospheric conditions?

Those are just considerations that come to mind immediately.

Good work, but too narrow in conclusion.
2 / 5 (4) Jan 22, 2015
Garbage in garbage out. A computer model is only as good as the assumptions. Not having read the paper or tested the model one event does come to mind to kill the animals up close, Summer and the rock strikes, plenty of dry plant material and a fire in every direction. That would have a rather drastic effect on animals a lot closer than new zealand.
2 / 5 (4) Jan 22, 2015
Since at the time of the event the oxygen content of the air was 30 to 35 percent, much higher than today it would not take much heat to ignite plants. I bet this research did not up the oxygen content from today which is back to Junk science.
2 / 5 (4) Jan 22, 2015
By the way, dinosaurs did not evolve into birds, birds evolved from animals living in dinosaur time. 99.99999999999999999999999999999 percent of dinosaurs are not related to birds, only the ones which are birds just like humans and all mammals evolved from a mammal ancestor alive when dinosaurs were around.
not rated yet Jan 23, 2015
Dead pine is my favorite fire starter. It has oils all over it and it reaches high temperatures fast. There are always dead or dried up branches on pine trees.
5 / 5 (6) Jan 23, 2015
Garbage in garbage out. A computer model is only as good as the assumptions. Not having read the paper or tested the model one event does come to mind to kill the animals up close, Summer and the rock strikes, plenty of dry plant material and a fire in every direction. That would have a rather drastic effect on animals a lot closer than new zealand.

GIGO indeed. Someone or something planted a GARBAGE idea IN your head and now nothing but GARBAGE comes OUT of your mouth.

IF you knew HALF of what you thought you knew, you'd be pretty smart.

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