I think the parent comment was downvoted because it's not really contributing anything besides pessimism. As for us, I don't doubt the likelihood of a serious

I think the parent comment was downvoted because it's not really contributing anything besides pessimism. As for us, I don't doubt the likelihood of a serious mass extinction, including possibly a severe drop in human population, but I can't see it being so severe as to cause an existential threat to us. No other species on this planet has had the ability to change the environment to suit it, or the ease of mobility to move where they can survive. Short of earth being entirely incompatible with complex life on the surface, I don't see humanity disappearing because of climate change.