Would a full scale thermonuclear war where Thousands of thermonuclear warheads are exchanged world-wide, result in the extinction of the human species?
Or would only about Three or Four Billion out of Seven Billion people in the world be annihilated in a single day?
The nuclear stockpiles today aren't even a tiny fraction of what they used to be during the peak years of the cold war. So a nuclear war in today's world wouldn't result in half of the losses in a massive nuclear exchange between the West and the old USSR.
Would human civilization rebuild itself and start over? Only to eventually become just as cruel, heartless, greedy
, and corrupt as it is today, and repeat that process indefinitely?
I'm sure there would be many places on Earth completely unaffected by the hypothetical global nuclear holocaust where many people would survive. Like small islands in the middle of the ocean, neutral countries like iceland and greenland, etc... I'm not sure about how the global nuclear fallout would effect the world and the survivors of the nuclear fire (birth defects and genetic mutations to the entire human gene pool caused by radioactive fallout) for Centuries or even Millenia after such cataclysm.
At the end of the movie "Terminator 3" there was an all-out nuclear war called "judgment day" triggered by a rogue artificial intelligence called "Skynet" which was given control of the missile defense systems in the North America. In the film, the protagonist named "John Connor" says that Three Billion (about half) of the entire human race was annihilated in a single day. It was a fictitious movie, but do those numbers sound accurate?
It's unlikely that we'll see anything like this happen in our lifetime, the time for this sort of thing came and went with the cold war. The political relations between all of the nuclear superpowers (US, Russia, China, UK, France) appear to be very stable, with the exception of North Korea. But there is still that small possibility all of that could change some day.