By SABRINA CHEN For The News-Letter
Parts of the Persian Gulf could reach heat and humidity levels intolerable to humans by the end of the 21st century. Authors Jeremy S. Pal of the department of civil engineering and environmental science at Loyola Marymount University and Elfatih A.B. Eltahir of the Massachusetts Institute of Technology (MIT) argued that human life in some population centers in the Middle East could be threatened by heat and humidity waves in a study published on Oct. 2.
The researchers attribute the increase in heat to humanity’s contribution to climate change and noted that the source of these potential summer climate extremities is a combined effect of both heat and humidity. The muggy heat that the researchers predict for future summers due to climate change could simply be too much for the human body to handle.
Usually we reduce our body temperature through sweating. However, sweating becomes less effective when humidity is too high. Furthermore the dilating of blood vessels in our bodies leads to increased blood flow near the surface of the skin. Our body heat is then lowered through convection when air flows over the skin. This can also become less effective when the heat is too high.
The paper, published in the journal Nature Climate Change, countered previous studies suggesting that such conditions would only be reached in 200 years. The study is based on new research and climate models that focus on regional topography and conditions.
Moreover, the study noted that because today’s heat waves already cause premature deaths by the thousands, the extreme conditions would be more intolerable to even the fittest of humans and could result in hyperthermia in just six hours of exposure.
The researchers relied on a method of measuring atmospheric conditions called the wet-bulb temperature. A wet-bulb thermometer can be used to describe the extent to which evaporation and ventilation can reduce an object’s temperature. Erich M. Fischer, a scientist at the Institute of Atmospheric and Climate Science at the science and technical university ETH Zurich, explained though he was not involved in the study that humidity does indeed have a great effect on human temperature.
“Anyone can experience the fact that humidity plays a crucial role in this in the sauna,” he told The New York Times. “You can heat up a Finnish sauna up to 100 degrees Celsius since it is bone dry and the body efficiently cools down by excessive sweating even at ambient temperatures far higher than the body temperature. In a Turkish bath, on the other hand, with almost 100 percent relative humidity, you want to keep the temperatures well below 40 degrees Celsius since the body cannot get rid of the heat by sweating and starts to accumulate heat.”
Fischer said that he found the research noteworthy, although some uncertainties remained in both the temperature measurements and the models. “Whether it exceeds or just gets close to the adaptability limit and for what period (which is probably quite relevant) may need further research,” he wrote in an email to The New York Times.
The study argued further that the heat and humidity conditions would not be constant. Spikes would instead become increasingly common and intense. Eltahir noted that a temperature that rank in the 95th percentile today would become a normal summer day by the end of the century. Wet-bulb temperatures exceeding the 95-degree threshold could occur once every decade or two.
Extreme climate conditions could have severe effects on the Hajj, an annual pilgrimage drawing over two million visitors to Mecca who pray outdoors from dawn to dusk. This ritual is likely to become hazardous to human health if the heat in the Middle East increases at the rate the researchers predict.
However, preventive tactics can reduce the likelihood of these extreme conditions in the Middle East if nations of the world reduce their greenhouse gas emissions. This effort would need to be applied at the global scale in order to dramatically reduce this increasing heat.