Look at it this way, the US and Russia have already been reducing the number of nuclear warhead, but sad to say they reduce by getting rid of the older bombs, only to build newer more accurate warheads. 

And who is to say which country would use them first, America of course, we have used them.  And after reading some of these posts, there are private citizens that appear to be quite willing to do it again.

And I've never heard how many kilo tons need to be used to burn up the planet, but we do know that a very few fired off into near space would destroy the electronics that would take this overpopulated, greedy, broke world and send it back at least to the 18th century. After which many in this world would turn to canabalism because there would be no way to feed everyone,  no way to get food to the masses.

The only way to get out with your life is through repenting to God, our Father, through His Son, Christ Jesus.  These are the only ones that can grant eternal life.  Whom in short order are about to return,  to redeem those that believe and to distroy the rest of earth, cleanising it and setting up the new order where there will be no weapons.