Do air conditioners help warm cities? – release

With the hot weather that has been down again on France since Friday. Consequently, and which should continue for several days, air conditioners are running at full speed. However, these devices are as appreciated as disputed. Similarly, Beyond the greenhouse gas emissions that it generates. In addition, air conditioning is accused by environmentalists of contributing to the phenomenon of urban heat islands, by evacuating the heat from the interior of the housing to the outside. In addition, A criticism swept by the supporters of air conditioning, most often from climatosceptic spheres.

In April. Furthermore, the publication by the Parisian From an article entitled “In Paris, air conditioning swarms and puts the city overheating” had revived the debate. Therefore, On the social network X, the journalist of Point Géraldine Woessner then split this comment: “It do air conditioners help warm is obviously false. Furthermore, Even in Paris, air conditioning is not responsible for the phenomena of heat islands. For example, ” And to send back to one of his own articles. For example, published in 2023, in which we read, however: “Air conditioning is indeed a major challenge for global warming […] By rejecting the hot air in the streets, the air conditioning tends to warm dense cities up to 0.5 to 2 degrees Celsius. In addition, ” However. Nevertheless, the journalist attributed the largest part of responsibility in the phenomenon of urban heat islands at the concentration of buildings, and to the waterproofing of surfaces.

What about? However, Even before the heat releases of human origin, the sun is obviously the main source of calories in cities. “During the day, the sun heats the waterproof surfaces and those of buildings. At night, this heat is do air conditioners help warm then returned to the atmosphere. This prevents air from cooling as quickly as above the vegetation. and creates the urban heat island ”Valéry Masson diagram with CheckNews. According to this researcher in urban climatology at the National Center for Meteorological Research. it is therefore fair to say that “Air conditioning plays a secondary role in the formation of heat islets in the city”.

A study to which Valéry Masson contributed. published in 2013 in the journal International Journal of Climatologyand relating to the air conditioning park existing in 2010 in Paris, goes in the direction of a low contribution of air conditioning. She showed that “During a heat wave, air conditioning increased the heat island by 0.5 ° C” in the capital, “While the total heat island was around 8 ° C”. The air conditioning therefore only participated in 6 % in the formation of the do air conditioners help warm heat island. But the study did not focus only on the year 2010. It envisaged different scenarios, including that of a “Expansion of air conditioners” by 2030. In this context. simulations indicate that “The night overheating due to air conditioning would reach 2 ° C in certain districts of the capital”note Valéry Masson.

However, it would seem that Paris has had an increasing number of air conditioners in recent years. In any case, that was the observation made by the article of Parisian mentioned above. He resumed the first conclusions of the study carried out by an association. the Parisian urban planning workshop, whose observations were in the sense of a “Massive and rapid broadcast” air conditioning in the capital.

Other more recent studies on the effects of air conditioning in Paris draw more alarming conclusions. Requested by CheckNewsthe Environment. Energy Management do air conditioners help warm Agency (ADEME) refers in particular to the work conducted by several researchers from the International Center for Environment and Development Research (CIRED), published in 2020 in the journal Environmental Research Letters. According to this study. in the event of a heat wave, “The massive appeal to air conditioning would accentuate phenomena of urban heat islands”being able to “Climbing the external temperatures of approximately 2 to 3 ° C”summarizes Ademe.

Researchers have reached this result by modeling “An Ile-de-France struck by a heat wave similar to that of 2003. lasting nine days”, and considering “That a majority of Parisian households will have chosen air conditioning”. More “If the heat wave was even more unbearable than that of 2003, the increase could be 3.6 ° C”underlines Ademe.

Economist specializing in the impacts of climate change in Cired. Vincent Viguié admits that “Hot -out heat do air conditioners help warm releases” remain “Low compared to other causes of global warming compared to their surrounding environment”. More “They are not negligible”estimates the researcher. Especially since none of the other phenomena that come into play in the formation of urban heat islands “Does not represent. by itself, the majority of warming”. The fact remains that discharges from air conditioning have the distinction of being “Very heterogeneous” : “They will strongly warm up certain places – where hot air discharges cannot evacuate because of the geometry of the street -. will play a negligible role elsewhere”. The air conditioners. however, have an advantage: “It is possible to act easily on these heat releases, while it is very difficult to act on buildings and surfaces.” Reducing the uses of air conditioning is therefore much easier than carrying out urban development work.

For Louis-Gaëtan Giraudet. another researcher in Cired, it would do air conditioners help warm be a question of leaving“A vicious circle” : “The urban heat island increases air conditioning needs and, in return, the use of air conditioning creates heat canyons.” At this point. he explains, “It is likely that this phenomenon is still relatively moderate in Paris, the rate of adoption of air conditioning being relatively low”. But heat islets could strengthen “Under the joint effect of global warming. the growing adoption of air conditioning, and the vicious circle that follows”.