Nuclear War

Nuclear war remains the most probable near-term existential risk due to escalating geopolitical tensions, proliferation of nuclear arsenals, and fragile command-and-control systems. Current flashpoints—including the Russia-Ukraine conflict, US-China tensions over Taiwan, North Korea's expanding arsenal, and Iran's nuclear program—create multiple pathways to catastrophic escalation.

Even a "limited" exchange could trigger nuclear winter through soot injection into the stratosphere, collapsing global agriculture and causing mass starvation. Modern arsenals contain thousands of warheads with yields far exceeding Cold War-era bombs; a full-scale exchange could kill billions directly and indirectly through cascading environmental and societal collapse. Unlike slower threats like climate change, nuclear war's destructive potential could unfold within weeks, making it the most immediate existential risk based on current global trajectories.