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Cities Are Sinking Under the Weight of Urban Development

A new study quantifies what big buildings are doing to the ground beneath San Francisco and other cities, as sea levels rise. 

Millennium Tower (left) in San Francisco has sunk 16 inches since construction was completed ten years ago. Other big buildings like it are contributing to sinking ground across the city, a new study warns. 

Millennium Tower (left) in San Francisco has sunk 16 inches since construction was completed ten years ago. Other big buildings like it are contributing to sinking ground across the city, a new study warns. 

Photographer: San Francisco Chronicle/Hearst N/Hearst Newspapers
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In late 2020, engineers began working on a $100 million project to stop San Francisco’s Millennium Tower from tilting and sinking further into the ground. Tenants of the beleaguered luxury condo had learned four years earlier that the 58-story high-rise had sunk some 16 inches in over a decade. But the tower’s predicament is only part of a larger problem, and not just for the Bay Area: Cities around the world are sinking under the weight of their own urban development — at the same time that sea levels are rising.

A new study seeks to quantify how much the sheer weight of the built environment contributes to the sinking of cities, a geological phenomenon known as land subsidence. While urbanization is just one small cause of this phenomenon among several, the paper in the journal AGU Advances estimates that its impact is only likely to grow as people move to cities in greater numbers. As a result, densely packed cities are likely to sink faster than less developed areas.