Sometimes human activities have implications that we are still unaware of. About our cities, we learn today from researchers. The result of overheating did not necessarily suspect.
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Underground global warming is a silent menace. » It is faith Northwestern University researchers (USA) after the work they just published. “Under the influence of temperature changes, the earth deforms. There is no civil structure or infrastructure designed to withstand these kinds of variations.” Even if the reasons are very different, there is no need to live in Venice, therefore, to live in a city threatened with collapse.
We already knew that as a result of human activities, the atmosphere is warming. The ocean too. But the land? According to the researchers, it is also warming up. by SpreadSpread Heat from buildings in our cities and underground transportation infrastructure. Studies have estimated this warming at between 0.1 and 2.5°C per decade in shallow soils. It’s massive!
Researchers already know that this underground global warming causes environmental problems – risks radioactive contaminationradioactive contamination Ground water, for example – and even health problems – are mounting in casesasthmaasthma or blows heatheat. They now know more about its impact on civilian infrastructure.
Ancient cities most at risk
For three years, the Northwestern University team patiently collected data from more than 150 researchers tentaclestentacles Installed everywhere in Chicago (USA). Including sensors buried in a green space on the edge of Lake Michigan. Researchers note that temperatures underground often appear 10 degrees Celsius higher than those below the park. As for temperaturesairair In underground structures, it can be up to 25 degrees Celsius higher than the ground temperature “not disturbed”. This phenomenon will be common in all densely populated urban areas of the world.
In another phase of their work, the researchers simulated underground warming to the year 2051 and how the Earth would deform in response. Because when heat spreads towards the ground, it exerts a pressurepressure important on the material. Some, like clay, knot and others, like limestone, expand. Models show that Chicago soils can swell up to 13 mm or sink as little as 8 mm. With the risk of seeing the appearance of cracks or settlements that are detrimental to the performance of the structures. but “Not enough to cause a building to suddenly collapse.”Reassure scientists.
“As the heat spreads towards the Earth, it exerts great pressure on the materials“
Still, researchers at Northwestern University believe that the oldest buildings, in the oldest cities like our European ones, can be seriously affected. However, they caution against the temptation to want to cool underground structures. This would be useless consumptionenergyenergy. While there are technologies that can recover waste heat and return it to buildings for heating. Or it is enough to install thermal insulation in buildings to reduce the amount of heat that penetrates the ground.
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