Global Warming May Make Persian Gulf Hotspots Too Hot for Humans by 2100

Summary: Global warming may make Persian Gulf hotspots too hot for humans by exceeding mugginess limits, a study in Oct. 26's Nature Climate Change finds.

Construction workers nap during heat/lunch break in sun-baked Al Sufouh, western Dubai: Paul Keller, CC BY 2.0, via Flickr

Increasing concentrations of man-made greenhouse gases could cause wet-bulb temperatures for Persian Gulf hotspots to exceed 35 degrees Celsius (95 degrees Fahrenheit), the critical mugginess survival limit for healthy people in well-ventilated outdoor conditions, finds a study published Oct. 26 in Nature Climate Change.

Even the fittest people are susceptible to hyperthermia, or abnormally elevated body temperature, after more than six hours of exposure to wet-bulb temperatures beyond the 35-degrees-Celsius threshold. Wet-bulb temperature considers both the air’s actual temperature, known as dry-bulb temperature or, simply, as temperature, and moisture content, known as humidity. For most people, who do not meet the ideal definition, the survivable wet-bulb temperature is lower than 35 degrees C. Such harrowing temperatures tend to be fatal for children, the elderly and individuals in poor health.

The study presents a model with an arbitrarily selected, extreme dry-bulb temperature of 60 degrees C (140 degrees F). The selected extreme temperature is a little higher than Earth’s hottest record temperature, officially reported by the World Meteorological Organization (WMO) as 56.7 degrees C (134 degrees F) at California’s Death Valley in 1913. Dry-bulb temperatures in the range of 40 to 60 degrees C (100 to 140 degrees F) affect not only the human body but also machinery, with aircraft malfunctions during takeoff and landing and rail line buckling. The Gulf’s average of maximum wet-bulb temperatures over almost three decades from 1976 to 2005 exceeds 31 degrees C (87.8 degrees F).

The study’s greenhouse gas concentration models for the end-of-the-century period from 2071 to 2100 predict annual wet-bulb temperatures in excess of 35 degrees C specifically for Abu Dhabi (United Arab Emirates), Bandar Abbas (Iran), Dhahran (Saudi Arabia), Doha (Quatar) and Dubai (United Arab Emirates). Near Mecca, Saudi Arabia, where pilgrims pray outdoors from dawn to dusk, wet-bulb temperatures are expected to rise to 32 degrees C (89.6 degrees F), with dry-bulb temperatures over 55 degrees C (131 degrees F).

A model based on measures to mitigate global warming considerably softens the dire forecasts for Persian Gulf hotspots. Wet-bulb temperatures would not exceed the 35-degrees-Celsius threshold. Actual air temperature would only exceed 55 degrees C in a few locations currently experiencing that range. With a temperature rise of only about 2 degrees C (3.6 degrees F), Mecca’s Hajj pilgrimage basically would be unaffected.

The study’s co-authors, Jeremy S. Pal, associate professor of civil engineering at Los Angeles’ Loyola Marymount University, and Elfatih A. B. Eltahir, associate department head of civil and environmental engineering at Massachusetts’ Institute of Technology (MIT), apply a regional climate model (RCM) to test the findings, published in 2013, by the physical science working group of the Fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate Change (IPCC) that manmade greenhouse gases are largely responsible for the recent decades’ global warming.

They identify their choice of the Persian Gulf, which they call the Arabian Gulf, as a major source for the local and global gas and oil that greatly contribute to past and present carbon dioxide emissions. The Gulf’s coastal geography is conducive to high humidity and high dry-bulb temperatures, with low-elevation, close-to-sea-level areas that encourage surface concentration of heat and water vapor. Cloudless skies, high absorption of solar energy (short-wave radiation), and high heat and water vapor retention due to a high evaporation rate at the surface account for the Gulf’s high wet-bulb temperatures.

The authors note: “Our results expose a specific regional hotspot where climate change, in the absence of significant mitigation, is likely to severely impact human habitability in the future.”

pilgrims in Mecca, Saudi Arabia, in September; photo by Ahmad Masood/Reuters: Assaad Razzouk @AssaadRazzouk via Twitter Oct. 26, 2015

Acknowledgment

My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.

Image credits:

construction workers during heat/lunch break in western Dubai: Paul Keller, CC BY 2.0, via Flickr @ https://www.flickr.com/photos/paulk/307513685/

pilgrims in Mecca, Saudi Arabia, in September; photo by Ahmad Masood/Reuters: Assaad Razzouk @AssaadRazzouk via Twitter Oct. 26, 2015, @ https://twitter.com/AssaadRazzouk/status/658779442693677056

For further information:

Assaad Razzouk @AssaadRazzouk. "Intolerable Heat Due To #Climate Change May Make Persian Gulf Uninhabitable Within Decades." Twitter. Oct. 26, 2015.
Available @ https://twitter.com/AssaadRazzouk/status/658779442693677056

Massachusetts Institute of Technology (MIT). "Climate change could bring deadly heat to Persian Gulf." YouTube. Oct. 26, 2015.
Available @ https://www.youtube.com/watch?v=W05c04Ge4-o

Pal, Jeremy S., and Elfatih A.B. Eltahir. "Future temperature in southwest Asia projected to exceed a threshold for human adaptability." Nature Climate Change, vol. 6: 197-200. Published online Oct. 26, 2015. DOI: 10.1038/NCLIMATE2833
Available @ http://eltahir.mit.edu/wp-content/uploads/2015/08/Paper.pdf

Warrick, Joby. "Report predicts temperatures too hot for humans in Persian Gulf." Boston Globe > Nation & World. Oct. 27, 2015.
Available @ https://www.bostonglobe.com/news/nation/2015/10/26/report-says-climate-change-could-push-persian-gulf-temperatures-lethal-extremes/8RvxLlDbgnl0co4PSywagP/story.html