Climate change is gradually narrowing the window in which the annual hajj Muslim pilgrimage can take place safely, according to new research by the World Weather Attribution group published on Friday.
The hajj pilgrimage to Mecca in western Saudi Arabia, one of the most arid places on the planet, is one of the world's largest religious gatherings – at which hundreds of thousands of pilgrims are now being exposed to extreme heat.
This year's gathering, which ends on Friday, was again held in temperatures exceeding 40C.
Global heating has "fundamentally altered" the climate of Mecca, the study by the United Kingdom-based group World Weather Attribution said.
Temperatures recorded in Mecca in May "are now typical of summer in the 1980s, as climate change shrinks the safe window" for the hajj, the study found.
Researchers said that by the end of the century, the hajj would take place amid dangerous heat almost all year round unless there was a rapid transition away from fossil fuels.
Saudi Arabia is the world's second biggest oil producer. A 2024 study found that its state-owned oil company Aramco generated 1.7 billion tonnes of CO2 in 2024, much of it linked to oil exports.
"If it were a country, Aramco would be the world’s fifth biggest carbon polluter, just behind Russia," the Guardian newspaper recently reported.
Longer extreme heat periods
The hajj's timing is governed by the Islamic lunar calendar, and moves back by about 11 days each year in the Gregorian calendar.
After taking place for several years during the hot season, this year's pilgrimage was at the end of May, and is expected to take place in mid-May next year.
The timing will move gradually closer to winter, offering a temporary respite, but this will not be enough to offset the rise in temperatures, the researchers said.
Climate change "is extending the duration of extreme heat in Mecca into historically cooler months," the study said.
"Average temperatures above 32C – typical of summer between 1970 and 1990 – are now expected almost every year in May. Climate change has increased these averages by about 3.5C" since pre-industrial times, it said.
The mainly open-air ritual, one of the five pillars of Islam, is held over several days in and around Mecca.
After more than 1,300 people died during the 2024 pilgrimage in searing temperatures of above 50C, when the hajj was in June, Saudi authorities strengthened anti-heat measures – mainly through the use of air conditioning.
The Saudi Red Crescent said on Thursday it had provided emergency services to "more than 83,000 people since the beginning of the hajj season".
A study published in 2019 in the US journal Geophysical Research Letters said heat stress during the hajj could once again exceed the "extreme danger threshold" between 2047 and 2052, and then between 2079 and 2086.
(with newswires)
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