Nuclear War

Rising geopolitical tensions and nuclear proliferation—particularly in volatile regions like the Korean Peninsula and Middle East—create a growing risk of deliberate or accidental escalation. The erosion of arms-control treaties (e.g., New START) further reduces stability between nuclear powers. A large-scale exchange (e.g., U.S.-Russia or India-Pakistan) could ignite global firestorms, injecting vast soot into the stratosphere. This would trigger nuclear winter, collapsing agriculture worldwide and causing mass starvation within years.

Unlike slower threats (e.g., climate change), nuclear war offers a singular, rapid pathway to civilizational collapse. Proxy conflicts, misinformation-driven brinkmanship, and untested command-and-control systems amplify the danger. While not guaranteed, the convergence of technical capability, geopolitical instability, and human fallibility makes it the most probable existential threat in the near term.