Researchers believe that an asteroid impact near what is now Sudbury, Ontario, Canada some 1.85 billion years ago may have triggered massive forest fires that filled the atmosphere with smoke and dust, blocking sunlight and causing a global cooling.
The Sudbury impact theory challenges the long-held belief that Earth's early atmosphere, which lacked significant amounts of oxygen, would not have been able to sustain crown fires over such a wide area.
"Our research suggests that the conventional view is not entirely correct," said lead researcher Chris Yakymchuk of the University of Calgary in Canada.
"While it is true that Earth's atmosphere at that time had very little oxygen, the impact itself and the subsequent burning of an estimated 10% of the world's forests, would have released enough carbon into the atmosphere to support widespread fires."
The study was published in the journal Nature Communications on Monday.
Meteor impact caused global 'nuclear winter'
Researchers used a combination of climate modeling and geological evidence to understand the impact of the Sudbury collision on Earth's environment and climate.
They found that the impact generated intense heat, which ignited forests across the globe and caused a 20-degree Celsius (36-degrees Fahrenheit) drop in average global temperatures. This extreme weather event, known as an impact winter, lasted for several years.
The massive amount of carbon dioxide released into the atmosphere from the fires created a greenhouse effect, warming the planet enough to support crown fires, but not enough to reverse the global cooling trend caused by the impact.
"The results suggest that the initial fires may have created the conditions necessary for more long-lived, self-sustaining fires, which could have contributed to the dramatic and enduring environmental changes observed in the geologic record," Yakymchuk said.
The Sudbury impact is believed to have coincided with a significant increase in the abundance and complexity of life on Earth, known as the Huronian glaciation.
While the mechanisms underlying the emergence of complex life during this period are still not fully understood, the researchers suggest that the unique environmental conditions created by the impact and the subsequent fires may have played a role.
"Our findings provide a new perspective on the relationship between large meteorite impacts and the evolution of life on Earth," Yakymchuk said.
