Human Exposure to Extreme Heat

The largest heat exposure in human history is unfolding. In 2000, roughly 200 million people lived in cities that experienced at least one month of 95°F+ (35°C) heat. By 2050, that number reaches 1.6 billion across ~970 cities. By 2075, 2.2 billion — and by 2100, up to 3.9 billion people will face these conditions annually. Nearly 1 billion will endure six months or more — transforming extreme heat from a weather event into a permanent season. The escalation is driven by three compounding forces: population growth concentrated in the hottest regions, accelerating urbanization intensifying heat-island effects, and climate forcing adding up to 4.7°C of warming under high-emission pathways. South Asia and sub-Saharan Africa bear the heaviest burden, but no continent is untouched. This dashboard simulates that trajectory, year by year, from 2000 to 2100.