Oddly enough I have dreams like this all the time, they change depending on the cataclysm, sometimes it’s universal destruction, other times it’s a totally freak occurence just effecting our planet or system (like a gamma ray burst going off in our vicinity and frying us all before we can blink)
The other night I dreamt some sorta crazy kinetic storm caused our poles to shift instantly, causing our gravity to fluctuate wildly and everyone just sorta fell up into the sky and died of whatever causes got them on the way up, shock, hypothermia, lack of oxygen, a lamp post or building or various objects also getting flung up (or falling down, perspective and direction is all but lost in such a situation). I have no idea of the exact science behind what could cause such a situation but I think about things like this all the time.
I try to imagine what it would be like to suddenly have a black hole manifest next to us and just crush us into oblivion in nano seconds. Thing is, sadly, we wouldn’t even notice, we are so tiny!