If, over the summers, you feel like you are getting hotter and hotter when you fall asleep, you are unfortunately right. The week of July 18, for example, the inhabitants of the United Kingdom experienced the hottest night on record, with temperatures around 25.9°C in certain regions, accustomed to much milder climates.
However, while rising nighttime temperatures are a phenomenon that is becoming increasingly common across the globe, scientists have so far been unable to determine why nights seem to be warming faster than days. reports New Scientist magazine.
A recent analysis of the temperatures of the past seventy years carried out by researchers from the China University of Geosciences in Wuhan could provide some answers. Their study published on June 29 in the journal Geophysical Research Letters revealed that since 1951, “the difference between night and daytime temperatures has reduced by 0.41°C”.
After considering a number of scenarios, “including a world without human influence, another with greenhouse gases from human activities and another with air pollution”, scientists have come to the conclusion that most of this warming is due to greenhouse gas emissions. In question : “Warmer air has more humidity, which increases the chances of cloudy skies, which reflect the sun’s rays during the day but retain heat at night.”
A worsening of the situation
“Due to Clean Air Laws, aerosol emissions have declined in Europe since the 1980s, leading to a reversal of the trend towards solar obscuration (pollution particles reflect light from the sun to space) in favor of clarification”explains Xihui Gu, a member of the research team behind the study.
Scientists also point out that hot and humid nights can be dangerous, because the sweat then evaporates with difficulty. This can, among other things, put a strain on some of our organs, such as the heart.
The study also specifies that this phenomenon could worsen over the years. The simulations have indeed revealed that the difference between night and daytime temperatures will continue to shrink and cannot be stabilized. “only if we reduce greenhouse gas emissions sufficiently”.