The ice-core and dendrochron records make it clear that the YD began with a precipitous temp drop, followed in 1200 years by a precipitous temp climb. Any alternative hypotheses have to explain those changes, well-established worldwide, simultaneous Pt and Ir deposits, two well-established gigantic meltwater pulses, and hundreds of well-established megafaunal extinctions, all falling among a period of deglaciation with a fuzzy timeline. For starters.

It's a tall order, and recent and ongoing discoveries have made it less-and-less fringey. Fascinating to watch the the responses and what they tell us about 'well-established' orthodoxy.