A new study fuels the debate on the striking of comet which changes the world 12,800 years ago

About 12,800 years ago, when the earth emerged from its last large ice period, temperatures in the northern hemisphere suddenly went up to almost glacial conditions. The cause of this brutal change – known as the younger period of Dryas Cool – is a mystery to date, but new evidence can give credibility to its most controversial explanation.

The researchers analyzed the nuclei of sediment extracted from the seabed of Baffin Bay near Greenland, finding indicators of a cosmic impact event inside the layer which is in correlation with the youngest. The results, published on August 6 in the journal Plos One, suggest that a comet – or its remains – explored in the atmosphere of the earth at the same time as this cold cliché of 1,200 years has started.

A controversial hypothesis

The study offers new support for the hypothesis of the younger Dryas. In 2007, researchers proposed that the fragments of a comet or asteroids were disintegrated struck the earth about 12,800 years ago, triggering forest fires across North America. Such calamity would have produced enough soot and ashes to erase the sun and plunge the northern hemisphere into a colder state.

This is an elegant explanation, but a very contested explanation. The researchers did not find an impact crater which would prove this event, so the supporters are largely based on the geochemical evidence found in the sediment layers which go up just before the start of the younger Dryas.

In the midst of a definitive lack of evidence of the impact hypothesis of younger dryness, most experts rather subscribe to the hypothesis of the pulse of fusion water, which suggests that a flood of fresh water from the melting glacial cap which covered most of North America during the Pleistocene temporarily interfered with the oceanic currents of the Earth. The previous geochemical evidence of oceanic sediment nuclei support this idea, but scientists have not yet determined the exact route taken by this apparent flood.

Search for impact indices

The authors of this last study, led by the archaeologist of the University of Southern Carolina, Christopher R. Moore, suggest that the two hypotheses can be true. “The impact hypothesis (younger of Dryas) is often cited as an alternative to the hypothesis of the pulse of melting water,” said Moore in an interview with Plos One. “What many do not understand is that the YDIH offers the impact event (potentially involving several thousand impacts and explosions on a global scale) would destabilize the ice cream sketch in the northern hemisphere, leading to the collapse of the lakes of the glacial fusion and then closed the ocean transport belt.”

Previous studies on the nuclei of terrestrial sediments have found geochemical clues of an impact of comet around the appearance of the youngest Dryas, but Moore and his colleagues wanted to see if the ocean nuclei would contain the same clues. If this is the case, this would dissipate the arguments that the earthly evidence of a younger Dryas impact event result from ancient human activities, according to Moore. His team discovered several impact proxys that go back to the appropriate period of time inside the ocean cores, including metallic particles with compositions that suggest the cometary origin and microspherus rich in iron and silica.

Skepticism remains

However, not everyone is convinced. “I do not see anything in this new article which overcomes chronic and continuous problems with their previous articles,” Marko Boslough, applied physicist and research professor at the University of New Mexico, told Gizmodo. As a frank critic of the hypothesis of the impact of younger dryas, he thinks that there are much simpler explanations which are more consistent with our current understanding of the impact and physics of aircraft, earth science and astronomy.

“On the surface, they report materials that seem exotic and impressive, but these are not expected from the results of extraterrestrial events, and I do not think that the authors have seriously considered more ordinary explanations,” said Boslough.