Surprising new evidence reveals that the Arctic Ocean was covered with a thick layer of ice and filled with freshwater at least twice in the last 150,000 years. Ultimately the study could explain strange and bizarre climate anomalies associated with these glacial periods.
With all the human meltdown going on these days, it is hard to imagine that our world is shrouded in ice. But this has been true in recent glacial times, when large parts of North America, northern Europe, Greenland, and parts of the Bering Sea were dominated by huge ice sheets. With much of the Earth ‘s water bound in this ice, and with sea levels much lower than they are today, something very strange has happened, of which we do not have modern analogues.
Fresh evidence presented today in Nature proposes a remarkable explanation for the remarkable deficiency of thorium-230 – an isotope that accumulates on the seabed of the salt oceans – in marine deposits extracted from the sedimentary layers of the oceans. farthest north of us. This is a possible indication that the Arctic Ocean was an ocean full of clean water, cut off from the rest of the planet’s oceans, and covered with a 3,000-foot (900-meter) ice cover.
Evidence suggeststhis happened at least twice, once between 150,000 and 130,000 years ago and then again between 70,000 and 50,000 years ago. These salt-free seas were covered with a large sheet of ice and it lasted for thousands of years, according to a paper, co-authored by Walter Geibert, a marine geologist from the Helmholtz Center for Polar and Marine Research at the Alfred Wegener Institute.
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Gaps of thorium-230 have been found in sedimentary corridors extracted from the Arctic Ocean, the Fram Strait (the corridor between Greenland and Svalbard), and the Nordic Swaterfall. This isotope is the result of smelting uranium, which is naturally present in saltwater. Thorium sticks to solid particles, moves to the seabed, buries it in sediment, and waits to be discovered by scientists.
A study of key samples dating back around 200,000 years revealed at least two periods in which thorium-230 did not exist at all. For Geibert and his colleagues, this indicated the existence of salt-free bodies of water.
“We found that the natural discovery of radioactive material, which is always left over by crossing sea water, was absent over a very large area for certain periods of time,” Geibert explained in post-d.
To explain this, the authors presented a view in which large ice shelves extended far into the Viking Seas, extending from the Bering Strait all the way to the Greenland-Scotland Ridge (GSR). These ice shelves formed a large dam, separating the Arctic from the Atlantic and Pacific Salt Seas. Low sea levels, in which waters were about 430 feet (130 meters) lower than they are today, contributed to this process. The now lonely Arctic basin began to fill with melting water, creating a subterranean freshwater sea, the authors speculate.
“The freshwater accumulated in the Arctic Ocean we are talking about would be larger in size than the Mediterranean Sea, but it was covered with thick layers of ice,” Geibert said.
As the authors go on to explain, the ice dams sometimes failed, resulting in heavier salt water entering the Arctic Oc.ean. When this happened, the salt water quickly spilled out the freshwater, pushing it over the shallow border into the Atlantic Ocean. This sudden ash of cold water into the world’s oceans could explain strange climate anomalies previously discovered by scientists, including sudden temperature spikes in the ocean. Greenland.
“The effect – rapid warming in the Arctic oceans and possibly temporary cooling of the Atlantic – explained for a while, ”Geibert explained. “What we are adding now is a possible explanation for some of these large movements in temperature circulation that have not been satisfactorily explained to date.”
He added: “We are confident that this concept will stimulate much debate and research – we now need models of this very complex physical position, linking them to other higher standards.quality records, ”he said. “Ironically, some of the clear signs from very cold times we have found should now help us to celebrate with warmer Arctic times in the past with more confidence.”
But, paleoceanographer Sharon Hoffmann, writes in the accompanying News & Views article, I poured some cold water on the new findings.
“Arctic sediments to date have been particularly difficult due to the lack of microfossils, and fluctuating sediment levels. So it is not certain whether the [thorium-deficient] times in the corries were carried out simultaneously at all sites across the ocean basins, ”wrote Hoffmann, who is not connected to the new research. Also, “fresh water is not fresh water [animals] they have been identified in the sediments involved, so there is direct evidence of freshwater entering the deep Arctic basin, ”she said.
That said, Hoffman said the new research offers “exciting avenues for future research” and that future geochemical and fossil analyzes could help support or challenge the idea. that the Arctic Ocean could be new. ”