This vast comet impact changed Earth forever with firestorms

Fragments of a 62 mile comet plunged Earth into a vast firestorm, scientists claim, with millions of square miles consumed by fire. The inferno took place roughly 12,800 years ago, new research has theorized. While it was, until now, effectively unknown, the scientists believe the comet's impact was greater than that which caused the dinosaurs to go extinct.

Dubbed an "extraordinary biomass-burning episode and impact winter," the unexpected ecosystem-shaking event took place when chunks of a huge comet collided with the Earth. Believed to have happened shortly after the end of an ice age, it triggered one of the largest biomass burning episodes in over 120,000 years. Moreover, it had a huge impact on human life on the planet.

The study was carried out by 24 researchers, and split into two papers that have been published in the Journal of Geology. They pinpointed the 62 mile diameter comet, fragments of which struck Earth, and the remainder of which still circulate in our solar system. The resulting fires burned approximately 9-percent of the biomass on the planet, with smoke flooding the skies and preventing sunlight from reaching the surface.

As a result, the planet began to unexpectedly cool again, with plants dying off and thus animal life struggling to find food. Glaciers which had begun to melt reformed, and the cometary impacts even changed how the ocean currents were circulating. The result, it's suggested, was a near-ice age that lasted for approximately a thousand years.

Indeed, it's theorized that it was the trigger event for the so-called Younger Dryas climate episode. That had been noted for an unexpectedly high peak in ammonium, which the researchers say could have come from the burning biomass. Soot concentrations indicate that approximately 10 million square kilometers of the Earth's surface could have been ablaze.

For larger animal species, it also meant a premature extinction, the researchers say. As for humans, populations would undoubtedly have declined, either from deaths from the fire storms, a shortage of food and shelter, or simply the longer-term health impact of the changed ecosystem. "Computations suggest that the impact would have depleted the ozone layer, causing increases in skin cancer and other negative health effects," Professor Adrian Melott, one of the authors of the paper, suggests.

The Younger Dryas period has been an anomaly in climate research, with a number of theories arising to explain why one apparently normal ice age should experience an unexpected resurgence. Indeed, speculation that a comet strike could be to blame is not new, though these two studies present some of the most extensive research into justifying that theory.

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