Originally Posted by Moulin
I would think breaking up would be more devastating regarding extinctions world wide
Actually, likely to be less, but there are those variables.
A single mass broken into several smaller will usually offer mopre surface area upon atmospheric entry to result in a greater mass reduction.
Destruction in general is a basic equation of mass times velocity(near constant for any sized object due to Earth's gravity well) equals impact results. Reducing a large single mass into many smaller ones will usually increase the total surface area subject to abolation~atmospheric resistence=heat burn off and in essense usually mean a smaller mass impacting.
However, spreading one LARGE impact into say a Dozen smaller impacts could result in a larger scale of destruction, especially from a human perspective/effects, but here the veriable is in the where and when. If mostly upon ocean could likely be "small scale", but if upon the right locations of hard land, say cities/urban areas could be very devestating.
Net "bottom-line", not something to roll dice on if avoidable.