I imagine humans will survive all but the most devastating hit but
civilization as we know it might be doomed. We have the advantage of
being very adaptable and we can eat almost anything if we have to. We
are also dispersed uniformly around the planet, so if any area is
spared, someone will be there.
It might just set us back a thousand years.
Heluva science fair experiment huh?
According to the experts the largest impact (not necessarily due to a
direct hit, but economically) will be on the United States.