American researchers conducted a study of data from many weather stations. According to the results, intolerable heat/humidity combos have recently appeared on Earth. And yet, the researchers did not expect such extreme episodes for thirty years!
Whether in extreme hot or cold climates, humans have always been able to adapt. Nevertheless, there are still limits and these can be dictated in particular by temperature and humidity levels unbearable. According to a study published in Science Advances on May 8, 2020, climate change signals the return of levels that have not existed on Earth for millions of years.
The study led by Colin Raymond of NASA's Jet Propulsion Laboratory focused on data from numerous weather stations. However, researchers have particularly studied the "wet bulb temperature" (TW), combining both heat and humidity measurements.
According to the results, between 1979 and 2017 there was a doubling of extreme weather events between between 27°C TW and 35°C TW . Scientists even mention exceeding 35°C TW in Jacobabad (Pakistan) and Ras al Khaimah (United Arab Emirates). If it was overrunsover a short period of time , these are of particular concern. By way of comparison, the 2003 heat wave which caused 70,000 deaths in Europe did not exceed 28°C TW. Fortunately, it was a dry heat wave.
Let it be said, 35°C TW is considered a lethal threshold for humans! The reason is simple:these conditions negate two body cooling mechanisms . Remember that human skin is at 35°C on the surface. However, if the outside air is at the same temperature, heat exchange is impossible. Thus, the only remaining solution to evacuate the heat is none other than sweating. On the other hand, in the case of a saturation of the air with humidity, we automatically find a strong disturbance of the sweating process. As a result, the body "overheats" and eventually gives up.
Climate scientists are considering the consequences of these high humid temperatures for only a decade. However, they very quickly identified the danger. Indeed, previous studies already predicted an overshoot of 35°C TW in the context of a particularly pessimistic scenario in terms of greenhouse gas emissions. On the other hand, this scenario estimated the appearance of the first overshoots around… 2050!
The study leaders believe that the gradual advance towards such humid temperatures represents a major challenge for humanity in the decades to come. In addition, many areas have been identified combining a presence in the subtropics and the proximity of oceans with extremely warm surface waters with continental heat waves. If Pakistan and the United Arab Emirates have already exceeded 35°C TW once, this could be the case in other areas of the Middle East and South Asia including India in the very near future.
