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<p> Researchers collect sediment cores of the Beaufort Sea during the 2013 fieldwork. LLOYD KEIGWIN / WHOI </p>
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<p> A team of researchers from the Scripps Institution of Oceanography at the University of California at San Diego and Woods Hole Oceanographic Institution found evidence of a mbadive flood of freshwater in the area. 39, west of the Arctic. about 13,000 years ago. </p>
<p> The discovery could put an end to a question open to scientists for more than 100 years. The existence of the cold snap, called the Younger Dryas, had been known for decades but the physical cause of its origin had eluded researchers who were traveling to points in the Atlantic Ocean, the east. from the United States and Canada. </p>
<p> In 2013, Scripps' Neal Driscoll, Woods Hole's Lloyd Keigwin and his colleagues set sail for the east of the Beaufort Sea to find evidence of the flooding of the Mackenzie River, which is the boundary between the Yukon and the Northwest. Onboard US Coast Guard Cutter Healy, the team collected sediment cores containing fossils of microscopic organisms known as foraminifers along the continental slope north of the Mackenzie River [19659010]. kilometers (~ 135 miles) from the mouth of the river. The oxygen isotopes conserved in foraminifera shells were proportional to a strong freshwater incursion derived from glaciers. </p>
<p> "The signature of the oxygen isotopes recorded in the foraminifera shells conserved in the sediments allowed us to take the source of the" 13,000 years ago, the glacial lake spilled on along the Mackenzie River, "said Driscoll, a geologist at Scripps and co-author of the study funded by the National Science Foundation." Radiocarbon dating on shells provided age constraints. It's exciting when pieces of a puzzle of more than 100 years come together. "</p>
<p> The brutal climate change triggered by the freshwater flood has ended more than 2000 years of warming," said Keigwin, oceanographer at WHOI and lead author of the study, published online today in the journal Nature Geoscience </p>
<p> Younger Dryas have triggered dramatic changes in regional climates: fresh water from glaciers has shifted from the Arctic to the Arctic. North Atlantic Ocean and disturbed a circulation circuit of Greenland.This model, the Atlantic Transverse Meridian Circulation (AMOC), transports equatorial warm waters to the pole and releases heat into the atmosphere. </p>
<p> This disruption caused significant cooling in Europe, The Younger Dryas takes its name from a flower (Dryas octopetala) that thrived in the colder conditions of the continent at that time. </p>
<p> The Younger Dryas n & # 39; lasted only 200 It's a period of warming that has lasted 20,000 years, but for scientists like Driscoll, it's an important example of how feedbacks affect the climate system. Global warming or cooling trends on Earth are not linear but are punctuated by inversions and accelerations like this one. Such events help scientists interpret current trends by distinguishing global climate signals from regional signals. </p>
<p> The next steps of future research, Keigwin says, will be for scientists to answer the remaining questions about the amount of fresh water delivered to the North Atlantic. "Events like this are really important, and we need to understand them better," added Keigwin. "In the long run, I think the results of this paper will stimulate further research on the amount of fresh water actually needed to bring about a change in the system and the weakening of AMOC, which certainly calls for more attention to the warming we see. in the Arctic today and the accelerated melting of Greenland ice. "</p>
<p> Earlier this year, an article from researchers at University College London and OMSI showed that AMOC had not reached its peak since the mid-nineteenth century, currently at its weakest point in the past 1600 years.The continuous weakening could disrupt the weather patterns of the United States and from Europe to the African Sahel. </p>
<p> In addition to Keigwin and Driscoll , Ning Zhao and Liviu Giosan of OMSI, Shannon Klotsko of Scripps Oceanography and Brendan Reilly of Oregon are co-authors of the document. State University. </p>
<p> For more information, please contact: information, visit scripps.ucsd.edu.found-arctic
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