Science explains the Younger Dryas freeze by the Gulf Stream shutting down but never explains what shut it down, and a comet impact is the elegant answer.

But what’s not really been addressed before is why that happened, why the Gulf Stream was cut, why a sudden pulse of meltwater went into the world ocean, and it was so much of it and it was so cold that it actually stopped the Gulf Stream in its tracks. And that’s where the Younger Dryas impact hypothesis offers a very elegant and very satisfactory solution to the problem.