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An asteroid that led to the extinction of dinosaurs did not cause global firestorms as previously thought, research shows.
A team of researchers from the Universities of Exeter and 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 would have been too short-lived to ignite live plant material. However 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, enough to enable live plant matter to ignite.
The experiments carried out in the laboratory showed that dry plant matter could ignite, but live plants such as green pine branches typically do not. 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.
However, if some animal communities 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.
The results of the study are published in the Journal of the Geological Society.
It was supported by a European Research Council Starter Grant, a Marie Curie Career Integration Grant, the Leverhulme Trust, the EPSRC and the Austrian Science Fund.
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