Out of the Ice-Age: Mega-Tides of the Arctic Ocean and the Bölling-Alleröd, Younger Dryas Transition

Abstract:

It has been established recently (Velay-Vitow, Peltier, and Stuhne JGR-O 2020) that a high amplitude M2 tide may have triggered and contributed to the forcing of the rapid deglaciations of the Hudson Strait ice stream, commonly referred to as Heinrich events, during the last glacial period. The required conditions for a tidally triggered marine-terminating ice stream instability include a retrograde slope of the ice stream bed at the edge of an ice sheet and high amplitude tides coincident with the grounding line. Prior to the Bölling-Alleröd, a paleo ice stream, known as the Amundsen Gulf ice stream, existed in the location of the present day Mackenzie River outlet to the Arctic Ocean. Additionally, it has been shown in Griffiths and Peltier (GRL 2008) that the Arctic Ocean was mega tidal at last glacial maximum. We find that the Arctic Ocean remained mega tidal until the beginning of Meltwater Pulse 1a, and that the amplitude of the M2 tide outboard of the Amundsen Gulf was extremely large. We show that the drainage route for Glacial lake Agassiz, the source for the freshwater which caused the Younger-Dryas, may have been initially cleared by a tidally triggered marine ice stream instability, thereby allowing the critical freshwater outlow to proceed.