Abstract

Near the end of the last deglaciation, as increasing Northern Hemisphere insolation was driving gradual warming, the northern hemisphere experienced a pronounced 1,300-year cold reversal known as the Younger Dryas Event. This period corresponds approximately with Greenland Stadial-1, the final stadial before the onset of the Holocene. Despite over a century of research, the origin of the Younger Dryas Event remains unresolved. The leading hypothesis, proposed in the 1980s, suggests that a meltwater pulse disrupted North Atlantic oceanic circulation, triggering widespread cooling. In 2007, an alternative theory emerged, proposing that a bolide either impacted or exploded above the Laurentide Ice Sheet, initiating not only the Younger Dryas Event but also numerous other global changes, including the extinction of North American Pleistocene megafauna and the rise of agriculture in the Middle East. More recently, volcanic activity has gained attention as a plausible trigger. This talk will explore these competing hypotheses, ranging from the conventional to the extraordinary, by evaluating the supporting evidence, strengths, and limitations of each, including insights from recent studies.