Researchers from Northwestern University have installed over 100 sensors in parking garages, basement boiler rooms, and subway tunnels in Chicago’s downtown Loop to monitor underground temperatures. Their research has shown that temperatures in human-made underground structures can be as much as 77°F (25°C) higher than undisturbed ground temperature, leading to a phenomenon referred to as “underground climate change.” This issue, distinct from atmospheric climate change caused by greenhouse gases, results from heat emitted directly into the sublayers of the ground by buildings and transportation systems.
The rising underground heat can lead to ground deformations, potentially causing city structures and infrastructure to crack. Major cities like Chicago, New York, and London are at risk of sinking due to this underground climate change.
Alessandro Rotta Loria, an assistant professor of civil and environmental engineering at Northwestern University, emphasizes that the problem is a direct consequence of human structures and activities. The excess heat trapped in the ground poses threats to public health, building structures, and public transportation.
The Biden administration has recognized the importance of addressing this issue and is focusing on underground resilience as part of its climate agenda. Transportation Secretary Pete Buttigieg acknowledges the need for innovative solutions, including revising the materials used for construction in response to climate change. The administration is promoting federally funded programs to encourage municipalities to undertake area-specific mitigation and resiliency projects.
Mitigating the problem would involve thermal insulation to prevent waste heat from escaping underground and causing ground deformations. Alternatively, the excess heat could be captured and used for geothermal energy to heat and cool buildings, with an estimated return on investment in about six years.