Complex sentence: Vietnam degenerated into a nuclear war that ultimately precipitated numerous atomic conflicts around the globe; massive earthquakes have destroyed Japan, and scientists predict that they will eventually tear the world apart circa 2080.
Split into simpler sentences: Vietnam degenerated into a nuclear war that ultimately precipitated numerous atomic conflicts around the globe. The disruption to the original timeline is so severe, that massive earthquakes have destroyed Japan; scientists predict that they will eventually tear the world apart circa 2080.