They examined systems from the late 20th century (1979-2001) and those in recent decades (2001-2023), highlighting the increasing impact of climate change.
“Extreme heat and temperatures exceeding 45 degrees Celsius are not uncommon in Mecca during summer.
“Some studies have shown concrete evidence that over the Arabian subcontinent, temperatures are increasing due to climate change.
Relief might be in sight for Hajj pilgrims in the coming years as Deoras points out that the occurrence of the Hajj is moving away from Saudi Arabia's core summer season.
If global warming continues, the region could be witnessing even more extreme temperatures and moist conditions by then.
Saudi Arabia faced one of the most extreme heatwaves in its history, tragically resulting in the deaths of over 1300 pilgrims during the 2024 Hajj pilgrimage. The mercury in Mecca and Medina, the two central cities for the pilgrimage, soared to levels, reaching up to 52 degrees Celsius at Mecca's Grand Mosque. This heat stress claimed the lives of pilgrims, with the majority of fatalities being from Egypt, Jordan, and Iran.
The Hajj pilgrimage, an annual Islamic ritual and one of the largest global annual religious gatherings, brings millions from around the world to Mecca, to perform religious rites.
Though there have been incidents of stampedes in the past that led to the death of pilgrims, this year, climate scientists said that the Hajj and the Saudi Arabia region faced its worst and deadliest heat crisis in history aggravated by climate change. The Saudi Arabian government attributed deaths to heat stress further complicated by the presence of unauthorised pilgrims.
Analysis of the Hajj Heatwave Crisis
Heatwaves on the days of the Hajj pilgrimage, between June 16 and 18, were up to 2.5 degree Celsius more intense today than they were at the turn of the century, a recent analysis said.
Scientists from the ClimaMeter group, a European Union-funded initiative that rapidly analyses the influence of climate change on extreme weather events, used 40-year satellite data to compare meteorological patterns. They examined systems from the late 20th century (1979-2001) and those in recent decades (2001-2023), highlighting the increasing impact of climate change. This comparison revealed how the frequency and intensity of these systems have changed, reflecting the effects of global warming over time.
“Temperatures in Mecca have been unusually high this year. We can term this as a very uncommon event,” said Davide Faranda, Climameter researcher at the National Centre for Scientific Research (CNRS), France. “During the Hajj pilgrimage temperatures reached 47 degrees Celsius, with Mecca's Grand Mosque experiencing 51.8 degrees Celsius.”
Faranda said contributing factors include high-pressure anomalies (where atmospheric pressure is significantly higher than the average for that region often leading to stable, clear, and dry conditions) over Saudi Arabia, negative pressure anomalies over Egypt, and warm winds from the Red Gulf, resulted in temperature anomalies of up to over 7 degrees Celsius.
Climatologists shared similar views. “Extreme heat and temperatures exceeding 45 degrees Celsius are not uncommon in Mecca during summer. However, temperatures exceeding 51 in this region are extreme, and there have been only a few incidences exceeding that level in the past. At such a high temperature, even a bit of moisture in the air leads to extreme discomfort, which is what happened in Mecca,” said Dr Akshay Deoras, a research scientist at the University of Reading, United Kingdom.
Madhavan Rajeevan, former secretary, ministry of earth sciences said, “During the period 14-17 June, temperatures in the Mecca region were above normal by almost 6 degrees Celsius, associated with a large-scale anticyclonic flow, which is a clockwise rotation of air indicating high pressure. This results in clear skies, suppressing cloud formation and precipitation, leading to prolonged periods of heat and dryness. This high-pressure system likely contributed to the severe heat.”
The region witnessed a confluence of hot and dry surface winds from arid regions of Saudi Arabia and relatively moist surface winds from the Red Sea, added Deoras. “This combination seems to have played an important role in setting up lethal conditions,” he said.
Unusual Temperature Spikes: A Climate Crisis?
According to the Intergovernmental Panel on Climate Change (IPCC) AR6 report, the Middle East, including Mecca, has been experiencing rising temperatures, heatwaves, and droughts, which are direct manifestations of climate change. The region has seen a marked rise, especially in the occurrence of heatwaves, with these events becoming more frequent, lasting longer, and reaching higher temperatures.
Climate scientists said that this spike was not an isolated incident but part of a worrying trend. “Some studies have shown concrete evidence that over the Arabian subcontinent, temperatures are increasing due to climate change. This trend is seen everywhere. The whole planet is warming up,” said Rajeevan.
Tommaso Alberti, ClimaMeter researcher at The National Institute of Geophysics and Volcanology (INGV), Italy said, “When comparing the period 2001-2023 with 1979-2001 Mecca experienced over 1.5 degree Celsius increase which we can attribute primarily to climate change.”
Human-driven climate change is the primary factor behind rising temperatures, said Faranda. “This is linked directly to fossil fuel burning and affecting the most vulnerable pilgrims. Reducing fossil fuel use is crucial to prevent reaching critical temperature thresholds and avoiding future tragedies.”
So what does a future scenario look like? Higher temperatures result in increased evaporation rates, which shrink water resources, dry out soils, reduce river flow, and lead to longer and more intense drought spells. “The IPCC projects that the Middle East will continue to experience a strong increase in heat extremes throughout the 21st century, including more severe summer dryness and higher amplitude heatwaves,” said Alberti.
Challenge of unauthorised pilgrims
While heat has always been a risk during Hajj, the number of casualties this year is notably higher. In 2023, there were at least 240 reported deaths attributed to heat-related illnesses. In 2015 however, a stampede resulted in over 2,400 deaths, marking the highest fatalities in the history of Hajj.
This year, more than 1.8 million pilgrims have registered to arrive, according to the Saudi General Authority for Statistics. Measures taken by the authorities included medical preparedness and hydration stations. However, the Saudi government pointed to the challenge posed by unauthorised pilgrims, who often bypass official routes and safety measures. These individuals, lacking proper registration and support, are more vulnerable to extreme conditions.
Dr Youssef Al-Harbi, a public health policy expert based in Riyadh, said, “Statistics might indicate that there may have been the highest number of unauthorised pilgrims in 2024. They tend to travel in large numbers without proper logistical support, which complicates crowd management and emergency response efforts during heat stress.” He suggested better regulation and enforcement, along with more inclusive planning to tackle this.
Measures to Ensure Pilgrim Safety
In response to the crisis, the Saudi Arabian government announced measures to enhance the safety of pilgrims. These include infrastructural changes, improved medical facilities, and more stringent regulations to manage the flow of pilgrims. Climate experts said this may not be enough.
“There is a need for enhancing public health initiatives through awareness campaigns and scheduling adjustments can help, such as conducting strenuous activities during cooler parts of the day and implementing staggered timings to reduce crowd density. Technological solutions such as early warning or heat alert systems with better data analysis and planning can be effective,” said Alberti.
Meanwhile, best practices from other regions could offer valuable insights. For instance, Alberti highlighted that collaborating with international experts on managing large-scale events during hot weather, using advanced cooling technologies as seen in Doha, adopting urban greening initiatives similar to Singapore's approach, and implementing health monitoring systems like those in Japan could be beneficial.
Relief might be in sight for Hajj pilgrims in the coming years as Deoras points out that the occurrence of the Hajj is moving away from Saudi Arabia's core summer season. “However, it will return to the summer period after around 2050. If global warming continues, the region could be witnessing even more extreme temperatures and moist conditions by then. This could make it extremely challenging for pilgrims. It is crucial that local authorities develop a long-term plan,” he said.
