2023-07-27 18:41:00
Scientists define the underground climate change as a “silent danger” that lurks below great cities. Until recently, its effects on civilian infrastructure had not been thoroughly investigated. They did know their links to groundwater contamination and even health conditions such as asthma and heart attacks.
But, a recent study from Northwestern University in the United States relates for the first time this phenomenon to the transformation of the soil under urban areas.
“The soil deforms as a result of temperature variations and there are no civil structures designed to withstand these variations”, says the study leader, professor of civil and environmental engineering Alessandro Rotta Loria.
You can also take advantage of this threat. According to Rotta Loria, this heating can be used as an energy resource if it is captured under the right conditions.
“It is a term that is used to describe the increase in temperature below the surface” summarizes Rotta Loria in conversation with BBC Mundo. “It is called so because involves changes in underground weather conditionsbut this has nothing to do with him climate change from the surface, even if it is another sign of human impact on Earth”, adds the expert.
In many urban areas of the world, heat is constantly diffused from cellars, underground transport systems, car parks, heating networks and the building materials themselves, which absorb and retain heat during the day and release it at night.
Underground climate change can cause subway tracks to deform, requiring frequent expensive repairsGETTY IMAGES
That is why cities are generally hotter than rural areas and are more exposed to the consequences of this phenomenon.
The first investigations on climate change underground began about 25 years ago. These temperature variations can affect normal plant growth, the way groundwater flows, people’s health, and the condition of underground transportation pathways, causing costly disruption each year.
Rotta Loria’s studies are the first to track the effects of this phenomenon on civil infrastructure. AND found that severe deformations of the subsoil can cause problems on the aesthetics and operational function of buildings, potentially necessitating costly, economical repairs.
Rotta Loria and his team’s study is the first to study in depth the effects of underground climate change on buildings, calling it a “silent danger.”
The safety of people, for the moment, does not seem to be compromised. “It’s not like a building is suddenly going to collapse. The structures are slowly sinking. The consequences could be very bad, but it will take a long time to see them”, says the expert.
“It is very likely that underground climate change has already caused cracks that we do not associate with this phenomenon because we were not aware of it,” he adds. Many buildings, even modern ones, were not designed to tolerate today’s temperature variations..
In any case, Rotta Loria says that modern buildings will cope better than older structures, for example in the historic centers of Europe, where many foundations of medieval origin persist. Each city would need an individual evaluation and further studiesbut in the case of Latin America, Rotta Loria points out that “the densest, on unstable and soft ground, will be more prone to suffer damage as a result of underground climate change.”
According to simulations made by Rotta Loria’s team, warmer temperatures can cause the soil to swell and expand upward by a dozen millimeters. They would also cause the ground to contract and sink several millimeters under the weight of a building, up to 8 millimeters.
And while this may seem subtle, it’s more than many building components and foundation systems can handle without compromising their operational requirements.
Route Loria pide that new constructions take this phenomenon into account so that the structures are more resistant and their dangers are mitigated in the long term. He also says that it is possible to install thermal insulation in existing buildings and minimize the amount of heat entering the ground.
Finally, it points out the energy opportunity that this warming represents if it is used appropriately. “There are geothermal technologies that can collect heat and manage it in heating buildingssurely enough to cover their demand”, explains the researcher.
The Northwestern University team installed a wireless network of more than 150 temperature sensors in a neighborhood of Chicago.
Chicago, in the state of Illinois in the United States, was used as a model to study how underground climate change affects the soil and foundations of buildingsNORTHWESTERN UNIVERSITY
For comparison, they also buried sensors in Grant Park, a green space far from buildings and subways. The data indicated that underground temperatures in the Chicago borough were up to 10 degrees warmer than those in Grant Park..
“We use Chicago as our living laboratory, but underground climate change is common to all dense urban areas around the world,” says Rotta Loria. Now These studies need to be replicated in other cities around the world to evaluate each case separately.
*By Jose Carlos Cueto
BBC Mundo
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