Claim: Climate change could pose danger for Muslim pilgrimage

When the Hajj comes in summertime, in some years it may not be safe for participants to remain outdoors

Pilgrims at the Great Mosque of Mecca on Hajj in 2008 Image: Wikipedia


For the world’s estimated 1.8 billion Muslims — roughly one-quarter of the world population — making a pilgrimage to Mecca is considered a religious duty that must be performed at least once in a lifetime, if health and finances permit. The ritual, known as the Hajj, includes about five days of activities, of which 20 to 30 hours involve being outside in the open air.

According to a new study by researchers at MIT and in California, because of climate change there is an increasing risk that in coming years, conditions of heat and humidity in the areas of Saudi Arabia where the Hajj takes place could worsen, to the point that people face “extreme danger” from harmful health effects.

In a paper in the journal Geophysical Review Letters, MIT professor of civil and environmental engineering Elfatih Eltahir and two others report the new findings, which show risks to Hajj participants could already be serious this year and next year, as well as when the Hajj, whose timing varies, again takes place in the hottest summer months, which will be from 2047 to 2052 and from 2079 to 2086. This will happen even if substantial measures are taken to limit the impact of climate change, the study finds, and without those measures, the dangers would be even greater. Planning for countermeasures or restrictions on participation in the pilgrimage may thus be needed.

The timing of the Hajj varies from one year to the next, Eltahir explains, because it is based on the lunar calendar rather than the solar calendar. Each year the Hajj occurs about 11 days earlier, so there are only certain spans of years when it takes place during the hottest summer months. Those are the times that could become dangerous for participants, says Eltahir, who is the Breene M. Kerr Professor at MIT. “When it comes in the summer in Saudi Arabia, conditions become harsh, and a significant fraction of these activities are outdoors,” he says.

There have already been signs of this risk becoming real. Although the details of the events are scant, there have been deadly stampedes during the Hajj in recent decades: one in 1990 that killed 1,462 people, and one in 2015 that left 769 dead and 934 injured. Eltahir says that both of these years coincided with peaks in the combined temperature and humidity in the region, as measured by the “wet bulb temperature,” and the stress of elevated temperatures may have contributed to the deadly events.

“If you have crowding in a location,” Eltahir says, “the harsher the weather conditions are, the more likely it is that crowding would lead to incidents” such as those.

Wet bulb temperature (abbreviated as TW), which is measured by attaching a wet cloth to the bulb of a thermometer, is a direct indicator of how effectively perspiration can cool off the body. The higher the humidity, the lower the absolute temperature that can trigger health problems. At anything above a wet bulb temperature of 103 degrees Fahrenheit, the body can no longer cool itself, and such temperatures are classified as a “danger” by the U.S. National Weather Service. A TW above 124 F is classified as “extreme danger,” at which heat stroke, which can damage the brain, heart, kidneys, and muscles, is “highly likely” after prolonged exposure.

Climate simulations considered by Eltahir and his co-investigators, using both “business as usual” scenarios and scenarios that include significant countermeasures against climate change, show that the likelihood of exceeding these thresholds for extended periods will increase steadily over the course of this century with the countermeasures, and very severely so without them.

Because evaporation is so crucial to maintaining a safe body temperature, the level of humidity in the air is key. Even an actual temperature of just 90 F, if the humidity rises to 95 percent, is enough to reach the 124 degree TW threshold for “extreme danger.” At a lower humidity of 45 percent, the 124 degree TW threshold would not be reached until the actual temperature climbed to 104 F. (At very low humidity, the wet bulb temperature equals the actual temperature).

Climate change will significantly increase the number of days each summer where wet bulb temperatures in the region will exceed the “extreme danger” limit. Even with mitigation measures in place, Eltahir says, “it will still be severe. There will still be problems, but not as bad” as would occur without those measures.

The Hajj is “a very strong part of the culture” in Muslim communities, Eltahir says, so preparing for these potentially unsafe conditions will be important for officials in Saudi Arabia. A variety of protective measures have been in place in recent years, including nozzles that provide a mist of water in some of the outdoor locations to provide some cooling for participants, and widening some of the locations to reduce overcrowding. In the most potentially risky years ahead, Eltahir says, it may become necessary to severely limit the number of participants allowed to take part in the ritual. This new research “should help in informing policy choices, including climate change mitigation policies as well as adaptation plans,” he says.


The research team included Suchul Kang, an MIT postdoc, and Jeremy Pal, a professor of civil engineering and environmental science at Loyola Marymount University in Los Angeles. The work was supported by a seed grant from the MIT Environmental Solutions Initiative.

Written by David L. Chandler, MIT News Office

Note: While it is my viewpoint that the science claims made in this study are speculative, and pander to climate alarmism, I realize that the topic could be an inflammatory one that may invite comments that would violate our policy and the policy of WordPress. Therefore, so that we won’t be a target of those who would seek to deplatform this website, I’m leaving comments turned off. -Anthony

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August 23, 2019 2:14 pm

So a fraction of a degree hotter 30+ years from now is going to cause WHAT to happen to people the vast majority of whom live in a DESERT climate?

Jeremiah Puckett
August 23, 2019 2:26 pm

It can’t be that important to them since only 0.1% of the Muslim population are doing it this year. If you had different people do it every year, you’d still only see 8% of the population do it assuming an 80 year lifespan. If they can’t do it now with trains, planes, and automobiles… well, just turn to Christ and all your troubles will be over. Read up on your teachings of Muhammad where he said to obey the teachings of Abraham. Abraham spoke about the coming of the Lamb. He didn’t speak of Muhammad who never prophecied anything specific.

August 23, 2019 2:32 pm

No commenting at all or just really time delayed until verified? Why not build an indoor type stadium perimeter around the site with a fabric roof that is inflated with air pressure, so it can be enclosed and air conditioned? Sort of like some of the football/baseball sports stadium’s that do the same but on a smaller scale. It would be doable, perhaps at great expense, but Saudi Arabia has a lot of monies from oil revenues and this would be one way they could make it safe and enjoyable for all Muslim’s to utilize in air conditioned comfort for a very long time to come.

August 23, 2019 2:37 pm

Correction: The Green New Deal will DESTROY Muslim Pilgrimage (Hajj) … by banning air travel for all but the politburo elites

August 23, 2019 2:38 pm

“Climate change could pose danger for Muslim pilgrimage”: the good news about Global Warming just keeps on coming out all the time!

Pop Piasa
August 23, 2019 2:43 pm

Anthony, it appears that comments are active.

August 23, 2019 2:44 pm

Just add more A/C. This is their air-conditioned tent city that can house 3 million people.

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August 23, 2019 2:44 pm

Wet bulb/dry bulb temperature explanation is utterly and totally wrong.
This is way more wrong than the usual fact mangling in a typical press release.

michael hart
August 23, 2019 3:11 pm


South River Independent
August 23, 2019 3:19 pm

Resistance is futile. According to Muslim beliefs, things happen only because Allah wills it. Allah controls the climate.

ferd berple
August 23, 2019 3:20 pm

A cheap umbrella more than solves the problem of standing in the hot sun.

And is à heck of a lot more reliable than trying to control the weather 50 years in the future.

August 23, 2019 3:21 pm

This is a fake science story written by someone who doesn’t understand the physics. Even the original story was wrong and had to be corrected. T sub w is never greater than the thermometer reading (dry).

James Poulos
August 23, 2019 3:24 pm

Yeah… I think most Muslims will simply accept this as they do in all other things. It is the will of Allah.

August 23, 2019 4:13 pm

Islam in danger of cooking itself.

Do I care?

No more than for any other fanatical god squad cooking themselves.

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