New research has added to the long list of changes that are happening around our climate. The Northwestern University in Illinois, US has unearthed a unique phenomenon called underground climate change and has linked it to the shifting that is taking place underneath our cities.
According to the study, the ground beneath urban areas is warming up, leading to subsurface urban heat islands. In simple terms, it means the underneath surface expands and contracts due to this heat, and that results in a shift in the ground. This can lead to crack formations, and affect the foundations of civil infrastructures.
It can be linked to various anthropogenic activities, like underground transportation, heat emitted from the usage of vehicles like cars and trains people use for their day-to-day travel. Also, underground pipelines, sewers, high-voltage cables, and district heating systems heat the ground.
The heating up of the underground surface has been developing for years and scientists have now linked this to previous incidents of building collapse.
The study states, there is a rise in the above temperature due to the daily absorption from construction materials of solar radiation. Also, other heat sources are leading to meteorological urban heat islands.
Scientists have termed this phenomenon ‘silent hazard’, as it may have a dormant yet potential impact on the civil infrastructures due to urban heat. “The root of this issue lies in thermally induced ground deformations and displacements, which develop slowly but continuously in the urban underground,” says the study.
According to the study, while the urban heat will not lead to the crumbling of buildings and other infrastructure, it will have an effect on the durability and operational requirements and also put a dent in the aesthetic part.
Even in the past, underground climate change has affected the loop, which has led to vertical displacement of several millimeters due to waste heat rejected by underground built environments, adds the study.
Even with a potential threat, there is a small silver lining that scientists have managed to figure out. If we are able to harness energy from the underground heat, we could utilise it as an alternate form of thermal energy.
“By capturing the waste heat emitted underground from subterranean transportation systems, parking garages and basement facilities, urban planners could mitigate the effects of underground climate change as well as reuse the heat into an untapped thermal energy resource,” adds the study.