A new study reveals that all 28 of the largest U.S. cities are experiencing land subsidence, with some areas sinking up to two inches per year, posing significant risks to infrastructure and increasing flood hazards.
Key Points at a Glance
- All 28 major U.S. cities analyzed are experiencing land subsidence.
- Houston leads with over 40% of its area sinking more than 5 millimeters annually.
- Groundwater extraction accounts for approximately 80% of the observed subsidence.
- Subsidence exacerbates flood risks and threatens infrastructure integrity.
- Study emphasizes the need for improved groundwater management and urban planning.
From the towering skyline of New York City to the sprawling suburbs of Phoenix, an invisible yet increasingly dangerous phenomenon is reshaping America’s urban landscapes: the ground beneath them is sinking. According to new research from the Columbia Climate School’s Lamont-Doherty Earth Observatory, every one of the 28 most populous cities in the United States is affected by vertical land motion – and in most, the trend is downward.
Using high-resolution satellite radar data from 2014 to 2020, the researchers mapped minute shifts in land elevation with unprecedented accuracy. The results are sobering: in 25 out of the 28 cities studied, more than two-thirds of the land area is sinking. In some areas, the ground is subsiding by more than two inches (5 centimeters) per year. Houston, Texas, tops the list, with over 40% of its land area sinking faster than 5 millimeters annually – in some hotspots, the figure is 10 times higher.
The culprit? Groundwater extraction, which accounts for about 80% of the observed subsidence. When cities draw excessive amounts of water from underground aquifers, particularly those composed of fine, compressible sediments, the structure collapses and compacts, causing the ground to sink. This is especially pronounced in cities like Houston and Phoenix, where population growth and industrial use place enormous pressure on water supplies. In Texas, oil and gas extraction further contributes to land deformation.
But not all causes are man-made. In northern cities such as New York and Chicago, natural geologic processes like post-glacial rebound also contribute to subsidence. These areas were once compressed by massive ice sheets during the last Ice Age. As the land continues to slowly readjust from that burden, parts of it sink. Even the very weight of a city’s buildings can have an impact – a 2023 study highlighted how the mass of New York’s infrastructure might be gradually pressing the city into the ground.
The implications of widespread urban subsidence are vast and multifaceted. Uneven sinking, known as differential subsidence, can cause roads to buckle, buildings to crack, and underground utilities to rupture. In flood-prone coastal cities, subsidence worsens the risks of storm surge and sea-level rise. For example, New Orleans and parts of Miami already sit perilously close to sea level. If land continues to drop while seas rise, their vulnerability multiplies.
In fact, the Columbia study estimates that roughly 29,000 buildings are currently at risk due to uneven ground subsidence – and the number will grow without action. As infrastructure ages, the added stress of land movement could result in mounting repair costs, insurance liabilities, and even public safety hazards.
What’s more alarming is how under-the-radar this crisis remains. Subsidence is largely invisible to the eye, gradual enough to be imperceptible until damage becomes obvious. Because of this, it often flies below the political and public radar. The researchers hope that their detailed mapping of city-wide vulnerabilities will help change that.
The study’s authors call for more robust monitoring systems, sustainable groundwater management policies, and the integration of vertical land motion data into urban planning. Solutions may include limits on groundwater withdrawals, investment in aquifer recharge technologies, and the redesign of infrastructure to accommodate slow, continuous shifts in elevation.
As climate change accelerates, subsidence could act as a silent amplifier of its worst effects. Coastal cities facing sea-level rise will suffer the most if their foundations are also sinking. The data is clear: addressing urban subsidence is no longer optional. It must become a central part of how cities prepare for a changing climate and expanding populations.
This new evidence adds a compelling layer to the broader narrative of urban resilience. For cities hoping to thrive in the 21st century, it’s not just about building upwards – it’s also about understanding what lies beneath.
Source: Columbia Climate School
