There are natural apocalypse like meteor strikes and super volcanoes. Then there are unnatural ones like Anthropogenic Global Warming is entirely human made. Also a nuclear war can cool things down for maybe a decade and might be as bad as a caldera explosion. Release of genetically modified life-forms that become hazardous or even dangerous should they get loose and alter once in the wild.
I could make the list much longer. But you get the idea.
June 13, 2017