Climate Catastrophe

The single most likely path to mass human extinction is catastrophic climate change. Current trajectories project 2.5–3°C of warming by 2100, triggering multiple tipping points—Amazon rainforest dieback, permafrost methane release, and ice sheet collapse. These feedback loops could push global temperatures beyond human survivability (wet-bulb temperatures >35°C in key regions), causing cascading food system collapses, societal breakdown, and billions of deaths. Unlike nuclear war or pandemics, climate change operates as a slow-motion catastrophe with irreversible momentum once critical thresholds are crossed. While geopolitical conflicts and AI risks remain serious, climate systems' inertia makes this the most probable extinction driver by 2100.