If we don’t limit greenhouse gas emissions, a number of cities in the Persian Gulf will experience never-before-seen combinations of temperature and humidity events that will be beyond the limits of human survival, according to a study published by researchers at MIT and Loyola Marymount University.
“The new study thus shows that the threats to human health [from climate change] may be more severe than previously thought, and may occur in the current century,” Christoph Schär of the Institute for Atmospheric and Climate Science in Zurich writes in a commentary accompanying the study.
The study, which shows the consequences of a “business-as-usual” scenario where nothing is done about greenhouses gasses, also points out that curbing emissions could forestall deadly temperature extremes. The study was conducted by Elfatih Eltahir, a professor of civil and environmental engineering at MIT, and Jeremy Pal PhD ’01 at Loyola Marymount University.
The scientists used an ensemble of high-resolution regional climate model simulations in predicting extreme “wet-bulb” temperatures in the region around the Arabian Peninsula. The term “wet-bulb” refers to a combination of heat, humidity, and air pressure, providing a measure of mugginess.
Scientists estimate the threshold for humans is a wet-bulb temperature of 35 degrees Celsius, or 95 °F for at least six hours. To further explain this, at sea level, the threshold would be reached when the air temperature reaches 116 degrees and 50-percent humidity. The heat index, in this case, would be an unbearable 177 degrees.
At high levels of heat and humidity, a healthy, young adult could be at risk. When it gets very hot, humans sweat, and as the sweat evaporates, we cool off. But when the humidity is very high, evaporation of our sweat is impeded, making it that much harder to cool off. These conditions can cause the body to lose its ability to regulate its temperature, a condition known as hyperthermia. If this condition is not reversed, death will result.
Earlier this year, over 2,500 people died in India when temperatures reached as high as 118.4 °F. And as Digital Journalist Paul Wallis noted in an article on the India/Pakistan heatwave in June, ” Heat waves have killed nearly 80,000 people since 2003 according to one recent analysis.”
The research team says the Persian Gulf region is highly vulnerable because of its low elevation, clear skies, and a water body that increases evaporation. The Persian Gulf is shallow, and the water temperature is high. This leads to strong evaporation and very high humidity. While the wealthy may enjoy the comforts of air-conditioning, the vast majority, and especially the poor will be at great risk.
“Some of the scariest prospects from a changing clime involve conditions completely outside the range of human experience,” a Carnegie Institution for Science climate researcher, Chris Field, tells the Associated Press. “If we don’t limit climate change to avoid extreme heat or mugginess, the people in these regions will likely need to find other places to live.”
This study, “Future temperature in southwest Asia projected to exceed a threshold for human adaptability,” was published in the journal Nature Climate Change and published online October 26, 2015.
