Rising Temperatures Could Soon Endanger Muslim Travelers on Pilgrimage to Mecca, LMU and MIT Researchers Find

Saudi Arabia’s extreme summer heat and humidity could pose health hazards to Muslim travelers making the annual religious pilgrimage to Mecca, according to a new study co-authored by researchers from Loyola Marymount University and Massachusetts Institute of Technology.

The researchers project that future temperatures in the region around Mecca could surpass the U.S. National Weather Service’s extreme danger heat-stress threshold as soon as 2020. Published in the journal Geophysical Research Letters, the study was co-authored by Jeremy Pal, graduate program director and professor of civil engineering and environmental science in LMU’s Seaver College of Science and Engineering, and MIT researchers Elfatih Eltahir and Suchul Kang.

“Considering that Muslims represent nearly 25% of the human population and Islam is the fastest growing major religion, management strategies associated with increased temperatures during Hajj are expected to be even more challenging,” Pal said. “Fortunately, Hajj organizers have already started to adapt to climate change. In recent years they have added misters spraying water along paths, tents with air conditioning, police with water hoses to spray water, and locations with large sun umbrellas.”

Hajj is the journey that all Muslims are expected to take at least once during their lifetime if they are physically and financially able. The pilgrimage in and surrounding Mecca in the Saudi Arabian desert occurs during the last month of the Islamic calendar, and it involves a significant amount of time outdoors; a disproportionate fraction of the pilgrims is elderly. This year from Aug. 9-14, an estimated 1.5 million people completed the pilgrimage to the holy city.

“If we continue on our current greenhouse gas emissions trajectory, non-infrastructural strategies may be required, such as reducing the number overall of pilgrims and limiting them to those in good health during the high-risk Hajj decades,” Pal said.

Mitigation efforts favoring something similar to the COP21 Paris agreement of 1.5 or 2 degrees Celsius global temperature increase will likely reduce the projected heat-stress intensity and frequency, Pal said. Nevertheless, severe and extremely dangerous heatwaves are likely to occur regardless of any realistic climate change mitigation scenario.

The study predicts that hot weather in the region will exceed a wet-bulb temperature – a measurement combining temperature and humidity – of 29.1 degrees Celsius, or 84.3 degrees Fahrenheit. At the NWS’ extreme danger threshold, sweat no longer evaporates efficiently, so the human body cannot adequately cool itself.

Using atmosphere-ocean global climate models, the study states that future climate change with and without mitigation will elevate heat stress to levels that exceed the NWS’ extreme danger threshold through 2020 and during the periods of 2047 to 2052 and 2079 to 2086, with increasing frequency and intensity as the century progresses.

If climate change proceeds on the current trajectory or even on a trajectory with considerable mitigation, aggressive adaptation measures will be required during years of high heat stress risk.

Read the full study here.