With the current nuclear arsenals of the world as they are. Little has changed in respect to the overall outcome of full-scale thermonuclear war.
It will simply be, the end.
The world came perilously close during the Cuban missile crisis (as in key's turned, fingers on the buttons.)
We're all still here because of the much exaggerated, yet very real phenomenon known as common sense.
It might not be so common, but it's there.
Whether or not it will remain enough? Only time will tell.
What I do know, is that at any time that is but one possible thing of many, that may at any time happen to bring on the end of the world.
- A sufficiently large volcanic eruption, could render us extinct. As has been the cause of several previous mass extinction events over earth's history.
- A sufficiently large meteor or comet strike, would send us the way of the dinosaurs. If you like science fiction. I recommend reading "Lucifer's Hammer" By Larry Niven & Jerry Pournelle. Very good fiction on the subject.
- A Gamma Ray Burst from the sun, ours or even a more distant star, could overwhelm the Earth's magnetic field. Dousing the planet in an enormous amount of gamma radiation. Imagine 10x9e Chernobyl disaster.
- Disease is always a possibility as well. Another plague to rival the Black Death of ancient Europe or the Spanish flu of the early 20th century.
You know what the one thing all of these possible events have in common?
The simple fact that right now. At this moment, there is nothing you or I, can do about it.
Nothing. Nada, zip.
So what's the sense in obsessing over it?