Nuclear War

The most probable path to global catastrophe is a nuclear conflict triggered by escalating geopolitical competition, regional wars, or miscalculation. Arms-control frameworks have weakened, nuclear arsenals are being modernized, and crises involving nuclear-armed states remain frequent. Even a limited nuclear exchange could ignite firestorms, inject soot into the stratosphere, and cause a nuclear winter, collapsing agriculture worldwide.

Climate change, ecological stress, social polarization, and disruptive technologies would not necessarily end civilization alone, but they increase the chance of conflict and reduce the capacity to manage crises. If nuclear weapons are used at scale, the combined effects of blast, radiation, infrastructure destruction, famine, and societal breakdown could make modern civilization unsustainable.