Future Heat Stress During Muslim Pilgrimage (Hajj) Projected to Exceed “Extreme Danger” Levels

The Muslim pilgrimage or Hajj, which is one of the five pillars of Muslim faith, takes place outdoors in and surrounding Mecca in the Saudi Arabian desert. The U.S. National Weather Service defines an extreme danger heat stress threshold which is approximately equivalent to a wet‐bulb temperature of about 29.1 °C—a combined measure of temperature and humidity. Here, based on results of simulations using an ensemble of coupled atmosphere‐ocean...