The impact to society would be much greater on a sociological scale then on a physical scale, many nukes are more than 8Mt, the likelihood of it hitting a highly populated area is lower still.
My point is, we have used nukes, so we know exactly what the worst case scenario is, and that’s about 20-50 million lives(hitting Tokyo or NYC). Equal to the number of deaths during the Spanish flu or half of world war 2. I think the comparison helps us understand what the risk truly is. I think the world would panic and likely loose more lives through chaos than the actual impact.
20-50 million is an extremely high worst case scenario estimate. An 8 Mt explosion detonated at a random point on earth would most likely not kill anyone.
