Heat Stress During Arba’een Foot‐Pilgrimage (World’s Largest Gathering) Projected to Reach “Dangerous” Levels Due To Climate Change

Abstract Arba'een, a Muslim pilgrimage, is one of the largest annual mass gatherings in world, with date fixed according to lunar calendar. Most pilgrims start their long walking journey from Basra/Najaf toward Karbala (about 70–500 km) and are significantly affected by outdoor weather conditions during this period. Here, based on simulations performed using carefully‐selected climate models, we project that heat stress pilgrimage likely reach “dangerous” level, defined US National Weather Service criteria, end century. Moreover, significant increase consecutive occurrence hot days nights expected within coming decades, which may cause high incidence heat‐related disorders as human body not recover daytime loads. Our study suggests sound adaptation measures stringent mitigation actions must be established ensure safe future.