If a Hydrogen Bomb was dropped on New York City, how much damage would it cause?

There was, but it destroyed the user’s computer.

This gadget vividly suggests two things:

  1. Most nuclear explosions are surprisingly manageable. A 140-kiloton ICBM warhead detonated above Manhattan results in “sunburn-like discomfort and skin redness” in Greenwich Village.

  2. An asteroid impact is less manageable than a nuclear explosion.