expression, noun
existential threat; life-or-death crisis
A crisis that threatens the very existence or survival of a person, organization, or entity. Often used in formal or serious contexts.
その会社は存亡の危機に直面している。
The company is facing an existential threat.
気候変動は人類にとって存亡の危機だ。
Climate change is a life-or-death crisis for humanity.
Compound of 存亡 (sonbō, 'existence or demise') + の (no, possessive particle) + 危機 (kiki, 'crisis'). The phrase is a straightforward combination of its parts.