Fingerprint of ancient abrupt climate change (Younger Dryas) found in Arctic

[muriel_volestrangler]

A research team led by Woods Hole Oceanographic Institution (WHOI) found the fingerprint of a massive flood of fresh water in the western Arctic, thought to be the cause of an ancient cold snap that began around 13,000 years ago.

"This abrupt climate change -- known as the Younger Dryas -- ended more than 1,000 years of warming," explains Lloyd Keigwin, an oceanographer at WHOI and lead author of the paper published online July 9, 2018, in the journal Nature Geocscience.

The cause of the cooling event, which is named after a flower (Dryas octopetala) that flourished in the cold conditions in Europe throughout the time, has remained a mystery and a source of debate for decades.
...
In 2013, a team of researchers from WHOI, Scripps Institution of Oceanography at the University of California San Diego, and Oregon State University, set sail to the eastern Beaufort Sea in search of evidence for the flood near where the Mackenzie River enters the Arctic Ocean, forming the border between Canada's Yukon and Northwest territories. From aboard the U.S. Coast Guard Cutter Healy, the team gathered sediment cores from along the continental slope east of the Mackenzie River. After analyzing the shells of fossil plankton found in the sediment cores, they found the long sought-after geochemical signal from the flood.

https://www.sciencedaily.com/releases/2018/07/180709111132.htm

A period of cooling about 13,000 years ago interrupted about 2,000 years of deglacial warming. Known as the Younger Dryas (YD), the event is thought to have resulted from a slowdown of the Atlantic meridional overturning circulation in response to a sudden flood of Laurentide Ice Sheet meltwater that reached the Nordic Seas. Oxygen isotope evidence for a local source of meltwater to the open western North Atlantic from the Gulf of St Lawrence has been lacking. Here we report that the eastern Beaufort Sea contains the long-sought signal of 18O-depleted water. Beginning at ~12.94?±?0.15 thousand years ago, oxygen isotopes in the planktonic foraminifera from two sediment cores as well as sediment and seismic data indicate a flood of meltwater, ice and sediment to the Arctic via the Mackenzie River that lasted about 700 years. The minimum in the oxygen isotope ratios lasted ~130 years. We suggest that the floodwater travelled north along the Canadian Archipelago and then through the Fram Strait to the Nordic Seas, where freshening and freezing near sites of deep-water formation would have suppressed convection and caused the YD cooling by reducing the meridional overturning.

https://www.nature.com/articles/s41561-018-0169-6

[Fred Sanders]

1. The McKenzie River Valley all the way along most of the Arctic Ocean shoreline

were near 30 degrees C. yesterday...almost 90F...incredible.

[Nitram]

2. It is interesting that a long period of warming could result in an event that suddenly reverses

the trend and initiates a very cold period. The variables are huge and involve things like the reflectivity of ice vs snow vs water. Ocean currents play a huge role in climate and can be suddenly disrupted by such an event. I always keep in mind the fact that the British Isles are habitable mainly because of the warm water current that moderates the colder temperatures at that latitude.