Academic Bun Fight: Was There or Was There NOT an Impact at the Beginning of the Younger Dryas?

No:

Wittke et al. (1) present evidence of a major cosmic impact at the onset of the Younger Dryas (YD) episode, including some markers found in the top of the well-known Usselo marker horizon (UH). This finding is contrary to our extensive radiocarbon dating effort from this horizon (2), which shows that the UH at Aalsterhut postdates the onset of the YD. Furthermore, Wittke et al. (1) misinterpret the origin of the UH: this horizon is a well-defined paleosoil that formed during the Allerød and the early YD in the top part of coversand. This coversand was deposited before the Allerød, during cold and dry conditions, and is part of the European Sandbelt. Wildfires were common and occurred throughout this period, rather than synchronously with the onset of the YD (3).

Yes!

Van Hoesel et al. (1) refer to nanodiamonds at the top of the Usselo horizon at Aalsterhut, The Netherlands, having an average age of 10.845 ± 0.015 14C ka (12.70 ± 0.06 cal ka) (1); they found no nanodiamonds outside hat layer. Earlier, nanodiamonds were reported at the top of theUsselo in Lommel, Belgium,∼30 km southwest of Aalsterhut, acknowledged as the Younger Dryas boundary layer (YDB) [Tian et al. (2)]; those researchers also found no nanodiamonds outside that layer.

It all comes down to dating.