Alright, so we pump energy into a chaotic system and obviously the extremes will get more exteme. Stronger hurricanse, colder hurricanse and snap freezes, deeper floods, wet bulb events further north than you think possible, whatever. This is the known unknown.
I am existentially afraid of the unknown unknowns. At what point do the phytoplankton I'm currently breathing the poop of have a mass extinction event? All of human civilization is about to drown on dry land and I spend 5 days a week maintaining software that charges people for turning on their lights.
I crave death I crave oblivion death to america death to capitalism death to me.
There's a Buddhist parable about getting hit with two arrows. You could imagine it in a scenario where you are on a battlefield and are struck by an arrow. But for some reason you freeze up and stare at it, so you get hit by a second. You should have taken cover.
Another way, more secular if you prefer that, is shooting yourself in the foot. That only happens when you're not watching what you are doing or thinking.
Existential fear and the unknown unknowns aren't something that you should seriously be afraid of. They are fears of fears, that something potential may be potential. Two degrees removed from reality. At least something more immediately threatening, you can act against.
Those more abstract dangers are for humanity as a group to deal with. Tackling them as individuals will result in anxiety. Focus on more immediate problems, or find others to tackle the more abstract problems together, knowing you still might not achieve anything material just yet