A tenth of the Earth’s surface was suddenly engulfed in raging flames 12,800 years ago.
The conflagration rivaled the one that took out the dinosaurs, and it was most likely produced by pieces of a comet 100 kilometers (62 miles) wide.
As dust clouds engulfed Earth, they triggered a mini-ice age that held the planet chilly for another thousand years, just as it was emerging from 100,000 years of glaciation. Life might resume after the flames were extinguished.
Adrian Melott from the University of Kansas, who co-authored a 2018 study detailing this catastrophic event, stated:
“The hypothesis is that a large comet fragmented and the chunks impacted the Earth, causing this disaster. A number of different chemical signatures – carbon dioxide, nitrate, ammonia and others – all seem to indicate that an astonishing 10 percent of the Earth’s land surface, or about 10 million square kilometers [3.86 million square miles], was consumed by fires.”
A vast number of geochemical and isotopic markers were measured from more than 170 locations throughout the globe, including a team of 24 experts, to peep back into the scorching flames and shock waves of this massive event.
One of the analyses performed was on pollen levels, which revealed that pine forests were abruptly burnt out and replaced with poplar trees – a species that specializes in covering barren area, as you could get if your planet was struck by a succession of large fireballs.
Parts of the comet that disintegrated in orbit are likely still drifting about our Solar System 13,000 years later.
High concentrations of platinum, which is commonly found in asteroids and comets, as well as high levels of dust, were found in the samples analyzed by the researchers, along with increased concentrations of combustion aerosols that would be expected if a lot of biomass was burned: ammonium, nitrate, and others.
Plants would have died off, food supplies would have been limited, and previously receding glaciers would have begun to advance again, according to the scientists. Human civilization would have had to adjust to the harsher environment, resulting in population decline.
“Computations suggest that the impact would have depleted the ozone layer, causing increases in skin cancer and other negative health effects,” notes Melott.
The scientists theorized that the broad impact of comet pieces, and the resulting firestorm, is to blame for the additional bit of cooling known as the Younger Dryas era. This transient increase in global temperature has been attributed to shifting ocean currents.
The comet impact, on the other hand, isn’t an entirely novel concept, despite the fact that this current study goes into great detail to try and discover evidence for it. For many years, scientists have debated whether a comet collision triggered the Younger Dryas event.
Not everyone thinks that the data indicates to a comet hit, but this extensive study adds to the evidence, as do ancient engravings discovered in Turkey in 2017 – carvings depicting a deadly impact from an interstellar object.
“The impact hypothesis is still a hypothesis, but this study provides a massive amount of evidence, which we argue can only be all explained by a major cosmic impact,” added Melott.
The study was published in the Journal of Geology here and here.
