The annual Islamic pilgrimage known as the Hajj sees thousands of Muslims from different countries make the journey to Mecca during the summer as part of their religious obligations.

The sheer number of participants of the Hajj, which could reach up to two million people, makes it one of the largest gatherings in the world.

However, a new climate study conducted by Massachusetts Institute of Technology (MIT) and Loyala Marymount University (LMU) scientists has found that the continued rise in global temperatures threatens to bring intolerable heat to the Middle East in the next few years.

Through the use of standard models of global climates, researchers Elfatih Eltahir of MIT and Jeremy Pal of LMU made forecasts of future humidity in the Middle East in order to determine "wet-bulb" temperatures.

Scientists use wet-bulb temperatures to measure the ability of individuals to tolerate intense temperatures, which is dependent on how the body can cool itself off through sweating.

Eltahir said that wet-bulb temperatures that reach up to 35 degrees Celsius (95 degrees Fahrenheit) severely impair the ability of the human body to tolerate such heating.

Compared to dry-bulb temperatures, wet-bulb temperatures have lower degrees of heat. The difference between the two measurements is greater in dry air settings and less in humid air environments. This explains why people often note that muggy heat is much more difficult to endure compared to dry heat.

Matthew Huber, a climate researcher from Purdue University but who was not involved in the recent study, explained how wet-bulb temperatures affect the function of the human body.

"It is often assumed that humans would be able to adapt to any possible warming," Huber said.

"But any wet-bulb temperature over 35°C for extended periods should induce hyperthermia, as dissipation of metabolic heat becomes impossible."

Current measurements of global wet-bulb temperatures seldom reach beyond 31 degrees Celsius (87.8 degrees Fahrenheit), according to Eltahir and Pal.

Countries surrounding the Persian Gulf, however, are registering temperatures near the 35-degree Celsius mark (95-degree Fahrenheit). This is believed to be caused by a combination of high temperatures and high levels of air humidity produced by the Gulf's warm waters.

In July, scientists detected dry-bulb temperatures in the Persian Gulf that reached beyond 50 degrees Celsius (122 degrees Fahrenheit). This translated to wet-bulb temperatures that reached 34.6 degrees Celsius (94.3 degrees Fahrenheit).

Impact of High Wet-Bulb Temperatures in the Gulf

In an accompanying essay to the MIT and LMU paper, ETH Zurich researcher Christoph Schär wrote that the study is the first of its kind to predict the potential effects of high wet-bulb temperatures on people living in around the Persian Gulf.

Schär stated that despite staying in covered and well-ventilated areas, people in the Gulf could still suffer the fatal impact of such extreme temperatures. Urban centers around the coast, such as Abu Dhabi, Doha and Dubai, have been found to be at a particularly high risk.

To help combat the effects of climate change, leaders of the Islamic community called on their fellow Muslims, including those living in oil-producing nations, to take an active stance in helping eliminate greenhouse-gas emissions.

However, governments in the Gulf region have made no assurances to the upcoming climate conference in Paris that they will conform to the limitation of carbon emissions.

The findings of the Massachusetts Institute of Technology and Loyala Marymount University are featured in the journal Nature Climate Change.

Photo: Muhammad Ghouri | Flickr