Paper on Comet/Asteroid Impact Causing the Younger Dryas Cooling.

[Minimalist]

From their conclusion...Page 9.

The nature of the impactor remains unclear, although we suggest that the most likely hypothesis is that of multiple airbursts/impacts by a large comet or asteroid that fragmented in solar orbit, as is common for nearly all comets. The YD impact at 12.8 ka is coincidental with major environmental events, including abrupt cooling at the YD onset,major extinction of some end-Pleistocene megafauna, disappearance of Clovis cultural traditions, widespread biomass burning, and often, the deposition of dark, carbon-rich sediments(black mat). It is reasonable to hypothesize a relationship be-tween these events and the YDB impact, although much work remains to understand the causal mechanisms

The climate did change and the megafauna did go extinct. Moreover, Clovis artifacts are present below the YDB but not above. I don't like coincidences. They make my balls itch.