What is the biggest danger to human extinction?
Global warming will work slowly. Nuclear war would be a lot faster and probably is a our biggest concern. We can see comets and asteroids coming, hopefully in enough time to do something about it (and yes, we can do things about that). Gamma ray bursts and nearby supernova can’t be controlled but SN are rare (maybe twice a century in our galaxy and none nearby with good odds) and GRBs are very unlikely to happen in our galaxy and pointed at us (ridiculously small odds). The Sun will become a red giant star in about 5 billion years and that will be the end of the Earth.
