The summer of 2024 shattered global temperature records, with extreme heat events contributing to thousands of excess deaths and billions of dollars in economic losses from reduced labor productivity, agricultural damage, and strain on fragile energy infrastructure. Conditions were particularly severe in parts of South Asia and the Mediterranean, where prolonged heat waves pushed human heat stress to dangerous levels. Understanding and preparing for extreme heat is an ever-urgent challenge, and one where climate science, public health, and urban planning meet. What drives deadly heat stress, and how is it expected to evolve as the planet continues to warm? How accurately can heat waves be projected, and what uncertainties remain in forecasting local impacts? How can societies better protect people from extreme heat, now and in a hotter fu...