54°C on a playground in Toulouse, when the “City Makers” collective notices that the Pink City is seeing red
In Toulouse (Haute-Garonne), the “City Makers” collective has launched a campaign to measure ground temperature. The objective in this period of heat wave, raise awareness and raise awareness of the presence of certain phenomena in the Pink City, such as heat islands.
The heat wave, or when the Pink City sees red… The high temperatures are well established in Occitania, and Toulouse is not immune to heat islands.
“First measurement point at 9:40 a.m. in the sun… 28.4 degrees. In the shade, 25.3. Let’s see the surface of the cycle path? 25.2. Finally, on the grass, 20.1… . For an ambient temperature of 27 degrees.” Asphalt, cobblestones, lawn… Arnaud Rivière is one of the “City Makers”a collective of a dozen members based in Toulouse.
As an amateur, armed with an infrared laser thermometer, the 44-year-old man instantly measures the temperature of the ground. The objective is to observe the evolution of the heat stored in the different types of soil over the course of the day and compare them to the ambient air temperature.
These surface temperature differences vary according to the different coatings, depending on the sunlight and the nature of the materials. Measuring them can complement the models made by scientists and help to understand how to reduce this urban heat island phenomenon.
Arnaud Rivière, collective The city makers
In the future Parc du Ramier, a major city hall project, the observation is unequivocal : there is a severe lack of shade, while the sun beats down on the concrete slabs.
The purpose of this measurement campaign is to understand what development policy can be implemented in each area. Here, more vegetation is needed.
Arnaud Rivière, City Makers Collective
A Paris investigation showed that revegetation can lower the temperature by precious few degrees. “This therefore gives us some leads to halve this heat island phenomenon here in Toulouse”says the volunteer.
For example, this playground within the park is deserted. Maybe because the ground is 54 degrees at 10 a.m….
Moreover, one can observe a slight difference in temperature between the blue colored coating and the light colored one, which indicates 52 degrees. On the new bridge, same observation. Proof that painting certain surfaces in white requires relieving these heat islands a little ?
“Materials that store heat release it at night”, explains Arnaud. This is also the case of the famous Toulouse red brick, which indicates a temperature of 36°C from 10 am.
Thus, a vicious circle sets in and if nothing is put in place, the heat island is fed continuously and autonomously.
The price of the canopy
At the end of August 2019, the structure of the first urban canopy in France was installed in Toulouse, in the heart of the Saint-Cyprien district. Imagined by the Parisian company Urban Canopy, it was to accommodate climbing plants, with the aim of revegetating the city center. The whole had to cover 100 m² and thus offer islands of freshness.
But, despite an autonomous watering system, problem : nothing or almost nothing has grown in three years and the corollas do not bring the expected shade. The Covid-19 and the choice of plant species not adapted to the Toulouse climate can explain the failure of the project… Qui cost between 5 and 10 000 euros. On the road, planting a tree would cost around 4 500 euros ; a price that could double depending on the work to be done on the surrounding ground.
If the town hall could appeal to the collective of City Makers, this is not the case.
It’s interesting to see how the city and public policies evolve over time in relation to climate change, in particular on the measures available, the training of staff in climate issues… We are just a collective, what we do can very well be done by the public authorities…
Arnaud Rivière, collective The city makers
In other larger districts, such as that of Montaudran, redeveloped three years ago, “Today the question of revegetation arises. What could have been an integral part of the project at the base…” regret Arnaud.
To escape the scorching heat, Toulouse residents and tourists walking the Place du Capitole crowd in the shade of the arcades. It must be said that the mercury already indicates more than 34 degrees… At 11 o’clock in the morning.
After a ride in a small train to visit the city, Dolores and her husband settled under the umbrellas equipped with misters of a café terrace. : “Then we will surely go to the cinema. The hardest part is in places where there are no trees … Fortunately there are parasols otherwise we would be in the heat wave !”, she exclaims. A server at the establishment shares the same sentiment : “We need foggers and air conditioning everywhere… Already doing nine-hour shifts is complicated, so with this heat…”
As for Thomas, on vacation in the Pink City with his two young children : “We stay inside, shutters and windows closed !”
If the famous Toulouse square has been the subject of a greening proposal, this does not seem to be on the agenda. Despite theaid of 500 million euros from the State to develop islands of freshness, last June, the City expressed itself on the constraints of such a project on the square : “IThere is a parking lot below Place du Capitole, so there is no land. And as it is a historical monument, we must have the approval of the architect of the buildings of France”.