A new analysis has found that global heating has fundamentally altered the climate of Mecca, exposing millions of Muslim pilgrims to extreme and dangerous heat even during months outside summer. The study, conducted by scientists from the World Weather Attribution group, reveals that carbon dioxide emissions from fossil fuels now regularly cause temperatures of 40C in May, a peak that was historically rare outside the summer months.
The research indicates that without a rapid transition away from fossil fuels, the annual hajj pilgrimage to Mecca will face dangerous heat almost all year round by the end of the century. Saudi Arabia, the world's second biggest oil producer and host of the pilgrimage, has been a long-term obstructer of climate action.
In 2024, more than 1,300 pilgrims died due to extreme heat and humidity during the hajj, which took place in June. The study found that May is now 3.5C hotter on average than before human-caused global heating, making the pilgrimage in May as dangerous as the height of summer used to be. The hajj follows the Islamic lunar calendar, meaning it falls earlier each year, and by the end of the century, about 97% of all hajj pilgrimages could endure dangerous levels of heat if global temperatures rise by 3C.
The Saudi authorities have introduced heat action plans, including shaded walkways, cooling stations, and misting systems, which have helped reduce heat-related illnesses. However, Professor Friederike Otto at Imperial College London, an author of the study, stressed that reactive measures are not enough. She said: 'If we don’t rapidly reduce our dependence on fossil fuels – an industry at the very centre of the Saudi economy – we are resigning ourselves to the fact that millions of Muslims will be forced to carry out the hajj rituals in a climate that is simply unsuitable for it.'
Dr Emmanuel Raju at the Copenhagen Centre for Disaster Research added: 'Extreme heat during the hajj presents a unique humanitarian challenge because it involves millions of people moving through an outdoor environment for days on end. Measures like misting fans and water stations are vital, but we must face the reality that if temperatures continue to climb at this pace, the health and lives of millions during their pilgrimage is at risk.'
