YD Boundary event again

3 Apr 2010

At www.physorg.com/print189257699.html the cause of the Younger Dryas rapid cooling event 12,900 years ago has been discovered according to an article in Nature (March 31st) - and is perhaps designed to quash the comet airburst theory. A mega-flood of water across the top of North America channelled melt-water from the ice sheet - which inconveniently disappeared several thousand years earlier (but there is no reason why it might not have been locked up as a huge lake in the meantime). The sudden inflow of fresh water into the North Atlantic, and presumably the North Pacific too, triggered the world into a near Ice Age scenario, glaciers returning to NW Scotland, across Ranoch Moor for example, and the extreme cool phase of weather lasted some 1400 years. Previously, it had been assumed melt-water had rushed down the St Lawrence defile and poured directly into the North Atlantic - shutting down the ocean circulation system in the process. Doubt was cast on this idea from two fronts. In Greenland ice cores the cooling happened abruptly - too quickly perhaps. Secondly, geologists could find no evidence of such a flood at that point in time. Now, in this revival of the theme, it is being suggested the flood waters went northwards - and poured into the Arctic Ocean. The combination of fresh water and salt water led to the creation of greater amounts of sea ice, it is then deduced, which in turn moved into the North Atlantic causing the Ocean Circulation system to shut down. The lack of heat, it is seriously touted, caused the Gulf Stream to come to a halt - and it must have been quick. The failure of the Gulf Stream caused temperatures in Europe to plunge to an average of minus 25 in winter - for well over a thousand years. Evidence of sediment loading along the coast of the Arctic Ocean was discovered - especially in the Mackenzie delta system. However, this would be expected after the melting of the ice sheet in any case - so the actual dating of these sediments is paramount to the thesis. There is bound to be a reaction against this article - in the long term. For the moment it is convenient as an argument against Firestone and West el al. We may note that it is not actually the Gulf Stream that warms NW Europe - apart from the coastal margins from Cornwall to Norway. The reason why the weather of Britain and Ireland is so wet and mild during winter is simply because as the earth rotates the winds blow from west to east - and it is the wind off the Atlantic that gives us the weather. This has been pointed out on numerous occasions, especially in the AGW debate - yet here we have scientists saying exactly the same thing. Why? 

We may note that like Firestone and West el al, this new research ignores the problem that there were three dryas events in the final stages of the Pleistocene epoch - and the Younger Dryas was not the worst of them. Now, if the ice sheet that reached to the Great Lakes region was in effect a polar ice cap set some miles south of the present pole the melting of that ice cap - much of it held in the Great Lakes and the myriad lakes that dot the Canadian Shield and further west, most of it would have run off into the Arctic Ocean via the extensive drainage system that can be seen on a map of Canada. Naturally, some evidence of this happening should be visible on the ground - in the appropriate geological drift system - which may actually what has been found by the researchers. Is it an article of faith that the sediments belong to the onset of the Younger Dryas? Of course, if the Arctic Ocean was a frozen body of water, as necessary in the Ice Age scenario, could so much water have flowed into the sea. It could if it had not been frozen - and there is evidence that large parts of Alaska and the Yukon were not frozen. Some geologists have even suggested Alberta and Saskatchewan may not have been buried under ice but were perhaps tundra - or something like that. How do you prove that? It requires reinterpretation of some of the geology - which is not about to happen. Hence, this new theory probably has mileage. Never the less it will be interesting in how the story progresses in the coming months and what exactly has been found.