Basements and train tunnels constantly leak heat, causing the land to sink and straining building foundations. Scientists call it “underground climate change.”
Alessandro F. Rotta Loria, an assistant professor at Northwestern University, walked through a boiler room of the Union League Club of Chicago to examine a temperature sensor. Credit... Rc Motor Heat Sink
Photographs by Jamie Kelter Davis
Raymond Zhong and Jamie Kelter Davis explored basements, rail platforms and a parking garage to understand how the ground beneath Chicago is heating up.
Underneath downtown Chicago’s soaring Art Deco towers, its multilevel roadways and its busy subway and rail lines, the land is sinking, and not only for the reasons you might expect.
Since the mid-20th century, the ground between the city surface and the bedrock has warmed by 5.6 degrees Fahrenheit on average, according to a new study out of Northwestern University. All that heat, which comes mostly from basements and other underground structures, has caused the layers of sand, clay and rock beneath some buildings to subside or swell by several millimeters over the decades, enough to worsen cracks and defects in walls and foundations.
“All around you, you have heat sources,” said the study’s author, Alessandro F. Rotta Loria, walking with a backpack through Millennium Station, a commuter rail terminal underneath the city’s Loop district. “These are things that people don’t see, so it’s like they don’t exist.”
It isn’t just Chicago. In big cities worldwide, humans’ burning of fossil fuels is raising the mercury at the surface. But heat is also pouring out of basements, parking garages, train tunnels, pipes, sewers and electrical cables and into the surrounding earth, a phenomenon that scientists have taken to calling “underground climate change.”
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