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12

The most accepted theory is that the Younger Dryas was caused by a large reduction or shutdown of the North Atlantic "Conveyor" because of a sudden influx of fresh water from Lake Agassiz and deglaciation in North America. (Although evidence for such an event is thus far lacking.) The global climate would then have become locked into this new state until ...

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Some authors thinks that the extinction of the Pleistocene megafauna (large mammals such as mammoths, etc.) was contemporaneous with the Younger Dryas (Firestone et al. 2007; Faith & Surovell 2009), while some thinks that it predates it by a couple thousand years (Gill et al. 2009). Whether or not it was contemporaneous with the Younger Dryas, it ...

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In addition to the theories mentioned by Azzie Rogers, there is another intriguing (but highly tentative) hypothesis: the YD may have been triggered by a large cosmic impact event. The results of a major study of impact-derived spherules at the time of the YD were recently published by Wittke et al. (2013). I should reiterate, though, that this is not ...

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The apparent contradiction comes primarily from #1 but #2 also pays a small role here... Temperature decreases during the Younger Dryas greater than $2^{\circ}$C are believed to have occurred almost exclusively above $30^{\circ}$N in latitude. The bulk of the tropics are thought to have been relatively stable during this time and the southern polar region ...

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The best graphic I can find is a chart from NOAA covering various changes across the Younger Dryas: GISP2 data is inferred from ice cores in Greenland, Cariaco is shallow sea temperature inferred from sea-shell deposits in Venezuela. The indication is an abrupt 10 C drop in temperatures in Greenland, and about 3 C in Venezuala. Note that these are two ...

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