Study: The ground underneath Chicago city is gradually deforming due to ‘underground climate change’

Scientists are claiming that the ground beneath Chicago is experiencing gradual deformation due to what they call “underground climate change.” This phenomenon, known as “subsurface heat islands,” is caused by the heat released by buildings and subterranean transportation systems like subways. The research suggests that rising temperatures are leading to significant changes in the land in urban areas, which could pose a threat to buildings and infrastructure, jeopardizing their long-term durability.

Lead study author Alessandro Rotta Loria, an assistant professor of civil and environmental engineering at Northwestern University, explains that temperature variations are impacting the soil, rocks, and construction materials. For instance, when the ground underneath buildings heats up, it can contract and cause undesired settlement.

Although the deformations caused by underground climate change may be relatively small in magnitude, they develop continuously and can become significant over time, particularly affecting the operational performance of civil infrastructure like building foundations, water retaining walls, and tunnels.

This study comes after scientists announced in May that New York City may be sinking under the weight of its own buildings, with approximately 1.68 trillion pounds pressing down on the ground beneath.

To reach their conclusions, the researchers installed 150 temperature sensors across the Chicago Loop district, both above and below ground, in various locations such as basements, tunnels, and parking garages. Additional sensors were placed in Grant Park along Lake Michigan to compare temperatures in an unbuilt area without excess heat from construction or transportation.

Data collected over the past 25 years revealed that the ground under the Loop was up to 18 degrees Fahrenheit (10 degrees Celsius) warmer than the ground beneath the park. This temperature difference leads to the diffusion of heat towards the ground over time, giving rise to the phenomenon of underground climate change.

Loria points out that the consequences of underground climate change can include groundwater contamination, problems with underground railways, such as track buckling, and discomfort or health issues for passengers due to excessive heat.