The only way I ever see the Earth abolishing nuclear weapons is to either A) form a single world government (which is a scary idea in of itself); B) create a new weapon that has greater utility and destructive capability rendering nuclear weapons obsolete.  Even with joint monitoring and thorough protocols for their elimination, their is simply not enough trust in the world for nations to agree to such a prohibition.  Even if they were abolished, the fear would remain that someone hid some away in a remote location, or that one nation is better equipped than others to produce a new nuclear weapon more quickly. And we have yet to even consider the widely supported view that nuclear weapons may have actually prevented WWIII by their mere existence.  Prohibition summits are an act in futility.