Vienna, Austria - A new study warns that climate change is creating serious and growing risks for millions of pilgrims performing Hajj, with extreme heat and humidity already pushing human physiological limits during the 2024 pilgrimage. This research, led by Atta Ullah and his team from the Weather and Climate Services, Islamabad, Pakistan and Climate Analytics, Berlin, Germany respectively, suggests that, without urgent adaptation and global climate mitigation, the world's largest religious gathering could become increasingly dangerous in the decades ahead.
The findings show that during several hours of the 2024 Hajj, heat stress conditions exceeded survivability thresholds even for young, healthy adults.
The authors also state that in June 2024, the combined impact of heat and humidity created a period of approximately four consecutive hours during which prolonged outdoor exposure became potentially fatal without access to cooling or immediate relief. The danger is intensified during physically demanding rituals, when walking and movement can push the human body beyond safe limits even faster.
Our analysis shows that on June 17, 2024, the combined effect of heat and humidity breached the survivability threshold for even young, healthy adults for approximately four consecutive hours. During this period, the human body cannot maintain a safe core temperature through sweating alone, making unshaded outdoor exposure life-threatening. Says Atta Ullah.
Hajj is one of the five pillars of Islam and a mandatory pilgrimage for Muslims who are physically and financially able to perform it at least once in their lifetime. Each year, millions of pilgrims travel to Makkah to carry out a five-day sequence of rituals that includes circling the Kaaba, walking between Safa and Marwa, standing in prayer at Mount Arafat, spending nights in Mina and Muzdalifah, and the stoning of the devil, known as Rami al-Jamarat. These rituals take place in hot outdoor conditions that are becoming increasingly difficult to endure as global temperatures rise.
The study identifies the Day of Arafat as the highest-risk ritual, since pilgrims spend the entire day outdoors on the open plain of Arafat with minimal shade infrastructure. The research suggests that this part of the pilgrimage will be especially difficult to maintain in its traditional form if heat conditions continue to worsen. While some adaptations are already visible, including indoor performance of Sa'i and the construction of more permanent shelters and structures in Mina, these changes improve safety while also altering the traditional setting of the pilgrimage.
The authors note that future Hajj seasons will face a shifting climate pattern. Although the pilgrimage will occur during relatively cooler seasons for the next 20 to 30 years, it is expected to move back into hotter periods around 2050. At that point, the risks of extreme heat exposure are projected to intensify again, making future pilgrimages even more vulnerable to dangerous conditions.
The study combines sub-daily station-based temperature and humidity data from the 2024 pilgrimage with climate model projections to assess both current and future risks. Its conclusion is clear: adaptation measures can reduce some of the danger, but they cannot fully eliminate the threat if warming continues. The authors argue that mitigation is essential not only to protect pilgrims, but also to preserve the essence and traditional practice of Hajj itself.
Climate change is no longer only an environmental issue: It is now affecting religious practice, human health, and mass gatherings on a global scale. For Hajj, one of the most sacred and physically demanding journeys in the world, the threat is immediate, severe, and growing.
Text written by Asmae Ourkiya.
