Tsar's destructive force was incredible, but I think it bothers me a lot more that the US built 500 B41 bombs with a 25Mt yield during that era. What's the functional destructive difference between 50Mt and 25Mt? Zilch, any practical target hit by it is gone.
I agree it would be hard to be sure you had gotten every last one, but it would be easy to ensure that the survivors live in a new stone age with nuclear fallout making most of the earth uninhabitable for people, if not most life. I've been somewhat amazed at how resilient the biome around Chernobyl has shown itself to be, but I'm sobered by the measurable losses attributable to it that accident as well.
