SCIENCE

Cities are in danger: climate change undermines their foundations

Scientific research has been able, for the first time, to quantify the effects of the climate change we are witnessing in recent years on soil, city foundations and modern infrastructure.

The study was conducted by Northwestern University and published in Communications Engineering, a journal of the Nature group. The group also developed a forecasting model up to 2050, taking the US city of Chicago as an example of other modern megacities.

What emerged from this research is that the effects of climate change on the soil, especially of so-called 'subterranean heat bubbles', are serious and incisive, but could also represent an asset, if technology is able to store and reuse all the heat that propagates underground in cities.

Di Terabass - Opera propria, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=11848631
Climate change endangers the foundations of cities
Scientific research has been able, for the first time, to quantify the effects of the climate change we are witnessing in recent years on soil, city foundations and modern infrastructure.
Ansa foto
The study
The study was conducted by Northwestern University and published in Communications Engineering, a journal of the Nature Group. The group also developed a forecasting model up to 2050, taking the US city of Chicago as an example of other modern megacities.
Di Sea Cow - Opera propria, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=124625428
What the scholars revealed
As the ground heats up, it deforms. This phenomenon causes the foundations of surrounding buildings to shift excessively, and also encourages the creation of cracks, which affects the long-term operational performance and durability of structures. Scholars have also realised that these phenomena are caused by global warming, and therefore warn that it is not a problem that will solve itself, but rather one that will worsen.
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Because it could be an opportunity
If a way could be found to capture the waste heat that is emitted underground from underground transport systems and also from the sun heating the ground, from car parks and underground structures, urban planners would be able to mitigate the effects of climate change underground and, above all, a way could be found to reuse this heat as a source of heat energy that has never before been exploited. A solution that would therefore go precisely in the direction of the 'green' that has been sought in recent years.
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The words of Alessandro Rotta Loria
Alessandro Rotta Loria of Northwestern, who led this groundbreaking study, said: 'Underground climate change is a silent danger. The ground is deforming due to temperature variations and no existing structure or civil infrastructure is designed to withstand these variations; although this phenomenon is not necessarily dangerous to people's safety, it will affect the normal day-to-day functioning of foundation systems and civil infrastructure in general'.
Di Lol19 - Opera propria, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=12225530
The case of Chicago
Recently, Rotta Loria and his team placed a wireless network of more than 150 temperature sensors throughout the Chicago Loop, both above and below ground. The sensors were placed in places such as building basements, underground tunnels, underground car parks and underground streets such as Lower Wacker Drive. Once enough temperature data had been collected for three years, the researchers built a 3D computer model to simulate the evolution of ground temperatures from 1951, the year Chicago completed the underground tunnels, to the present day and found values consistent with those measured in the field. They then used this data to build a predictive model up to 2050.
https://upload.wikimedia.org/wikipedia/commons/5/54/Jay_Pritzker_Pavilion,_Chicago,_Illinois,_Estado
The underground of Chicago
Loria again talks about how the subsoil of Chicago, the city that was sampled in the study, is set: ''Chicago's clay can contract when heated, like many other fine-grained soils. As a result of rising temperatures in the subsoil, many foundations in the city centre are undergoing undesirable, slow but continuous settlement; in other words, you don't have to live in Venice to live in a city that is sinking, even though the causes of these phenomena are completely different'.
Di Mark Fischer - Bangkok Expressway, CC BY-SA 2.0, https://commons.wikimedia.org/w/index.php?curid=
Why cities are warmer
The answer is actually quite simple. Speaking in general terms, cities are warmer than rural areas because building materials periodically trap heat from human activity and solar radiation and then release it into the atmosphere.
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19/04/2024
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