Nearly 2 million Muslims are concluding their haj pilgrimage this week, but the extreme heat has been deadly for hundreds.

Since the journey to the Kaaba at the Grand Mosque in Mecca began last Friday, at least 562 people have died, according to a Reuters tally from foreign ministry statements and other sources.

Egypt has reported 307 deaths and 118 missing, with temperatures soaring past 51 degrees Celsius (124 Fahrenheit).
"The heat was unbearable," said Wilayet Mustafa, a Pakistani pilgrim. Witnesses reported seeing bodies covered with white Ihram cloth on the roadside near Mina, just outside Mecca, until medical vehicles arrived.

Climate scientists warn that such fatalities are a preview of the future challenges for the tens of millions of Muslims expected to undertake the haj in the coming decades. Carl-Friedrich Schleussner, a scientific advisor at Climate Analytics in Germany, noted that while the haj has always been conducted in hot climates, the current climate crisis is exacerbating the conditions.

Rituals like the climb of Mount Arafat have become "incredibly dangerous to human health."

The timing of the haj, determined by the lunar calendar, means it will shift back by 10 days annually. While the haj is moving toward winter now, by the 2040s, it will occur during Saudi Arabia's peak summer. "It is going to be very fatal," said Fahad Saeed, a climate scientist at Climate Analytics in Pakistan.

Heat-related deaths during the haj have been recorded since the 1400s, with a lack of acclimatization to high temperatures, intense physical exertion, exposed spaces, and an older population making pilgrims particularly vulnerable.

Last year, over 2,000 people suffered from heat stress, according to Saudi officials. The situation is expected to worsen as the world warms. A 2021 study by Saeed and Schleussner found that if global temperatures rise by 1.5 C (2.7 F) above pre-industrial levels, the risk of heat stroke for pilgrims will increase fivefold. The world is on track to reach this level of warming in the 2030s.

Saudi Arabia implemented a heat strategy in 2016, which included constructing shaded areas, establishing drinking water points every 500 meters, and improving healthcare capacity.

Health authorities advised pilgrims to stay hydrated and avoid being outdoors between 11 a.m. and 3 p.m. during this haj. However, Pakistani pilgrim Mustafa reported that when he tried to rest while pushing his 75-year-old mother in a wheelchair, police told him to keep moving. He criticized the lack of shelter and water.

The Saudi government did not respond to requests for comment. An Egyptian medical source indicated that the highest death tolls were among unregistered pilgrims who were forced to stay on the streets, exposed to the heat. Egyptian pilgrim Sameh Al-Zayni mentioned receiving water from Saudi authorities, and a Reuters witness saw police distributing water and spraying crowds to cool them.

However, scientists noted that spraying water is only effective at temperatures below about 35 C (95 F). At higher temperatures, it can be counterproductive in humid conditions, making it harder for people to cool down through sweating.