Wow! Half of humanity is a pretty large portion. I don't know if it's really to 'mass extinction' levels at that point.
I'd say the easiest way to slice it would be a simple matter of age. The oldest 50 percent of humanity dies, leaving the 50 percent with the most potential time to flourish. While going through on a case by case basis may produce a slightly better list, it would take far too much time in an emergency.
Let's say for example about half of humanity.
Wow! Half of humanity is a pretty large portion. I don't know if it's really to 'mass extinction' levels at that point.
I'd say the easiest way to slice it would be a simple matter of age. The oldest 50 percent of humanity dies, leaving the 50 percent with the most potential time to flourish. While going through on a case by case basis may produce a slightly better list, it would take far too much time in an emergency.