[ncmncm]

You have just pushed the mystery back a step. What caused the failure of the Atlantic meridional overturning circulation? What reversed the failure 1200-odd years later?

Evidence for a bolide strike producing a huge meltwater pulse, to start the process, is accumulating, coinciding with extinction of 30+ genera and the sudden end of the Clovis culture. Another strike at the Holocene boundary is less well supported; but we do need a cause.