Forget about nuclear winter. Humans are resilient. We will survive. So how many nukes will it take to destroy every single human being in the planet, on first blast? Here's the calculation in graphic form—with a surprising answer.
The first part of the graphics—created by David McCandless—shows how much space is actually used by the entire population. According to the Guardian Datablog and the Bulletin of Atomic Scientists, only 12.5 per cent of the planet's surface is actually occupied by humans. A total of 18,617,500 square kilometres.
Now, the most powerful active nuclear warhead in the world is the B83, which has a destructive power of two hundreds Fat Boys, the bomb that destroyed part of Hiroshima. That's a 14.9 square kilometre total destruction area. Complete instant tanning, and obliteration of anything in sight. To give you an idea of what this space means, Manhattan is 58.8 square kilometres. Central London is 26 square kilometres.
Now divide the total number of square kilometres by the destruction radius of the B83 to get the total number of nukes required for instant annihilation. As you can see, we need 123.36 times the amount of nukes available today.
Conclusion: WE NEED MORE NUKES, NO LESS. Better die instantly than having to survive nuclear winter and another yet another horrible movie with Mel Gibson playing Mad Max. One that would last for a few hundred years at that. [David McCandless—Thanks David Keyes]