Pre-publish article: http://www.theregister.co.uk/2013/0...d_for_triggering_younger_dryas_climate_shift/ Mukul Sharma of Dartmouth claims there is very good evidence that the extremely rapid draining of Lake Agassiz about 12900ya is only a partial contributor to the cold period (Younger Dryas) that started 12900ya. There is geological evidence of a large meteor impact in Quebec at the same time. He claims that is the primary cause. The register article mentions other posited effects: start of the Megafauna extinction, an increase agriculture by Native American peoples. I think we should reserve judgement until the paper is out. But a "head's up" is in order. This will be out shortly in PNAS, which is kind of home to somewhat speculative articles sometimes. IMO. Obviously they are refereed papers.