canton of bernWhat the measurements of a climatologist in Biel say
Urban areas are more affected than the countryside, according to data collected by Mortiz Gubler.
The heat is stronger in cities than in the countryside. Climatologist Moritz Gubler, who installed a temperature measurement network in Biel, demonstrated this, reports “Le Journal du Jura”.
At 31, Moritz Gubler is a climatologist and professor. He conducts research on urban climate and heat islands at the Institute of Geography at the University of Bern. Before installing its thermometers in Biel, its climatology research group operated a similar measurement network in the city of Bern for four years.
If cities overheat, it is due to a lack of vegetation, but Moritz Gubler highlights the impact of the sun’s rays on urban materials: concrete, stone and asphalt have a great capacity to accumulate heat.
In cities, buildings retain the rays: the heat absorbed is sent back to the ground instead of spreading into the atmosphere. Held back by buildings, the wind does not serve as natural air conditioning.
The size and density of buildings are very important to Moritz Gubler. In large Swiss cities, temperature differences linked to buildings can reach six to eight degrees. Globally, differences of up to 12 degrees were observed in Montreal or Mexico City.
The variations occur mainly at night: the phenomenon of urban heat islands is a nocturnal phenomenon. “During the night, the surrounding rural areas cool more quickly, while the city retains more heat”, the researcher told the “Journal du Jura”.
“We can expect a climate similar to that of Valencia in the city of Bern in the future”, predicts Moritz Gubler. Biel is located 100 m below Bern and, above all, the watchmaking city has a lake. During the day, this body of water causes a cooling effect through increased evaporation. At night, on the other hand, the lake has a heating effect, the water being a heat accumulator.
Bern has neither the Jura nor the Taubenloch gorge, from which cold air is channeled to the city of Biel. It is about reinforcing the revegetation with the planting of trees, when there is room for the roots. Temporary plantations are useful, such as the containers placed in the pedestrian zone of Bienne. Another idea is to reflect some of the radiation through lighter surfaces: Los Angeles is experimenting with white paint on the streets.
Gravel surfaces are also interesting. They reflect light several times in different directions and allow water to evaporate from the ground. According to Markus Brentano, head of the Department of Green Spaces of the City of Biel, “trees are mandatory”, as he told the “Jura Journal”.
Markus Brentano’s thermometer is his wet shorts as he walks past the reflective black facade of the Manor store. “Today in Biel is like in Montpellier a few decades ago,” he said.
Olive trees have returned to bloom in a vacant lot on rue Alfred-Aebi. As for the almond trees planted experimentally in the municipal park, they hibernated without any problems.
Trees ingest large amounts of water: an adult linden drinks 200 liters a day in hot weather, an oak up to 1000 liters.