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Younger Dryas … once more to the gates

7 August 2013

At http://phys.org/print295014415.html … there is a nice graph here to start the ball rolling, using five cores that show, with the aid of a blue band as highlight, the drop in temperature during the Younger Dryas (from Greenland, the tropics, and Antarctica). The graph purports to show a warming in Antarctica (Camp Century core) and this sticks out like a sore thumb, being slightly skew whiff from the other cores. This appears to be a leftover from the days when it was the clever thing to do to show Antarctica experiencing a downturn just before the North Atlantic, as a result of the ocean conveyor belt system (the consensus theory being that this was what had caused the Younger Dryas). Basically, the idea was that warm water from the Pacific equatorial zone was first pushed by currents into the Southern Ocean and then channelled up the Atlantic in the direction of Greenland – and there had to be a lag (which was duly found in the relevant ice cores). So, not only has the hockey stick graph been created in order to deny a medieval warm period or little ice age but it seems the favoured theory for the Younger Dryas may also have been given a little help on the way.

That is not of course the object of this story as Antarctic ice cores have problems of their own (see http://malagabay.wordpress.com/2013/07/19/etch-a-sketch-ice-sheets/ for example) but the graph is included only to show that the Younger Dryas had a global impact and it is PhysOrg catching up on the Harvard team and their paper in PNAS – as described in an earlier post. This concerns the discovery of a hundred fold increase in platinum in Greenland ice cores at the YD boundary – which the authors claim is evidence of some kind of cosmic impact.

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