The impact of a six-mile long asteroid believed to have hit the earth and wiped out the dinosaurs 66 million years ago would have sparked a cataclysmic firestorm, scientists say.
Over the past three decades scientists have argued about what caused the extinction 66 million years ago – changes to climate, volcano activity or an asteroid.
Research has already shown that the prehistoric animals died out around the same time a six-mile long object hit the planet, and a new model of the disaster suggests the asteroid’s impact would have sent vaporised particles of rock high above Earth’s atmosphere which in turn would have turned the sky bright red as they heated the upper atmosphere to 2,700 degrees Fahrenheit on re-entry.
‘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,’ study researcher Douglas Robertson, of the Cooperative Institute for Research in Environmental Sciences, or CIRES, said in a statement reported in LiveScience.com.
To put this into perspective, a 1-megaton hydrogen bomb is said to be the equivalent of 80 Hiroshima-type nuclear bombs.
The model, detailed this week in the Journal of Geophysical Research-Biogeosciences shows how the ‘heat pulse’ would have incinerated the world’s forests and everything else not protected underground or underwater.
The global firestorm theory has been aired before, with some scientists claiming that much of the intense radiation would have been shielded from Earth by the falling rock.
Factoring in this heat reduction, Roberts and his team maintain the atmosphere would still have been hot enough to ignite the world’s forests.
The team’s claim is bolstered by evidence of a layer of soot at the Earth’s 65 million-year-old Cretaceous-Paleogene boundary which would be consistent with global fires.
Some scientists argue that the charcoal’s presence is in fact from the impact of the asteroid itself – an argument countered by Robertson who says the asteroid alone would not have created quite this much.
Our data show the conditions back then are consistent with widespread fires across the planet,’ said Robertson.
‘Those conditions resulted in 100 per cent extinction rates for about 80 percent of all life on Earth.’
The asteroid’s impact near the town of Chicxulub in Mexico left a crater more than 110 miles (180 kilometers) wide.
The explosion itself would have released as much energy as 100 trillion tons of TNT, more than a billion times more than the atom bombs that destroyed Hiroshima and Nagasaki.
While the impact may not have been the sole cause of the dinosaur extinction, it almost definitely dealt the death blow, said researchers in February at Berkeley University’s Geochronology Centre in California.
Director Paul Renne said: ‘We have shown that these events are synchronous to within a gnat’s eyebrow.
‘Therefore the impact clearly played a major role in extinctions, but it probably wasn’t just the impact. The impact was clearly the final straw that pushed Earth past the tipping point.’
The asteroid collision with Earth has now been dated to 66,038,000 years ago. The new extinction date is precise to within 11,000 years.
Before the cosmic explosion, many creatures were brought to the brink of extinction by dramatic climate swings in the preceding million years, including long cold snaps.
Researchers used high-precision radiometric dating analysis of debris kicked up by the impact which would have radioactive materials within them.
The extinction of the dinosaurs was first linked to a comet or asteroid impact in 1980 by the late UC Berkeley Nobel Laureate Luis Alvarez and his son, Walter, who is a UC Berkeley professor emeritus of earth and planetary science.