Crater hidden under Greenland may explain a sudden climate change
Crater hidden under Greenland may explain a sudden climate change
Those who seek to reinforce their argument that not all climate changes are man-made may have received a pre-Christmas gift: researchers found a huge impact box of asteroids hidden in Greenland, whose age coincides with the beginning of a period of previously inexplicable cooling about 12,000 years ago. Does this change everything?
"The crater is exceptionally well preserved, and that is surprising, because the ice of the glacier is an incredibly efficient erosive agent that would have quickly eliminated the traces of the impact. But that means that the crater must be quite young from a geological perspective. "
in a Press release announcing the studyA large impact crater below the Hiawatha glacier in northwest Greenland", Published in the current edition of Science Advances, the co-author, Professor Kurt H. Kjær, of the Geo-Genetics Center of the Natural History Museum of Denmark, describes how researchers found for the first time signs pointing to the existence of the crater under the Greenland ice sheet in July 2015. It was not far from where a 20-ton iron meteorite had been discovered, but that was not enough to connect the dots.
Is not part of Greenland covered by glaciers?
A German research aircraft from the Alfred Wegener Institute flew over the Hiawatha glacier and, using a new ice radar system, could better see the image of the depression and added to the evidence, the enthusiastic NASA glaciologist Joseph MacGregor. (Photos here.)
"A clearly circular edge, central uplift, layers of disordered and undisturbed ice, and basal debris. It's all there. "
Surface expeditions in 2016 and 2017 collected sediment samples that were removed from the depression and found the missing link.
"Part of the quartz sand washed from the crater had planar deformation characteristics indicative of a violent impact, and this is conclusive proof that the depression beneath the Hiawatha glacier is a meteorite crater."
The crater measures more than 31 km (19.25 miles) in diameter, which places the size of the iron meteorite at 1 km (.6 miles) wide and places the impact on the 25 major impact craters on Earth, so which is a good candidate for causing ecological disasters. The ice sheets show that it is at least 12,000 years old and rock erosion samples say they are no more than 3 million years old.
It is the most recent date in which scientists link the event with the Younger Dryas period, a sudden and inexplicable cooling during a period of global warming after the last ice age. Occurring about 12,900 to 11,700 years ago, geological records in the Northern Hemisphere indicate a rapid drop in temperatures of 2 to 6 degrees Celsius (3.6 to 10.8 degrees Fahrenheit), increases in glacial ice and cold waters in the Atlantic and the drier general conditions. Although the cooling was generalized, some areas, in the southeast of North America, had a slight warming. The younger Dryas coincided with several human cultures that went from hunting and nomadic life to agriculture and settlements. In North America, the Clovis culture declined and several animal species became extinct.
All these things could certainly have been caused by a meteor impact of catastrophic size. Is that the answer to the cause of the younger Dryas that scientists have been looking for?
"The next step in the investigation will be to date the impact with confidence." This will be a challenge, because it will probably require the recovery of the material that melted during the impact from the bottom of the structure, but this is crucial if we want to understand how the Hiawatha's impact affected life on Earth. "
It seems that Kjær is making his plans for next summer. Pack a parka, professor!
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