Land subsidence is a growing threat due to climate change and population growth.

Land subsidence is a growing threat 

Study: 25 American cities are at risk of submersion, and Houston could disappear completely.

Twenty-five American cities, along with many others around the world, are at risk of being submerged in the future. Among these cities is the famous and historic Houston, which a study concluded could officially declare itself submerged and disappear from the world within years.

According to a recent study published by the British newspaper Financial Times, global climate change could cause 25 American cities to disappear and sink beneath the sea. The study concluded that "the problem of land subsidence affects not only coastal areas, where sea levels are rising due to climate change, but also inland population centers, where groundwater extraction hollows out sediments beneath the surface, while urban development adds additional weight above them. The end result is a slow landslide."

This slide can weaken vital infrastructure, including buildings, bridges, and sewer systems; reduce the water-holding capacity of aquifers; increase flood risk; and cause sinkholes. The new findings from this study reinforce the need to take land subsidence seriously, a risk exacerbated by climate change and population growth in urban areas. Just because land subsidence occurs slowly doesn't mean it should be ignored. Radar satellites can be used to measure land elevation by sending microwave pulses toward the ground and measuring how long it takes for the echoes to return.

Leonard Ohnen of Columbia University's Lamont-Doherty Earth Observatory collaborated with researchers, mostly from Virginia Tech, to examine data from the Sentinel-1 satellite collected between 2015 and 2021. By comparing echoes taken at different times over the 28 most populous cities in the United States, they were able to calculate how much the ground was moving either up or down. As they reported in their study, 25 cities showed, on average, subsidence rather than rise.

Among the US cities facing subsidence and submergence, the worst-performing were Texas cities Houston, Fort Worth, and Dallas, which showed average subsidence of more than 4 mm per year. Some parts of Houston are sinking by more than 10 mm per year, which seems small by the standards of other cities experiencing severe submergence, such as Jakarta and Tehran.

Indonesia has built a new capital, Nusantara, in part due to Jakarta's ongoing subsidence of up to 15 cm per year. About half of Jakarta, home to 11 million people, is now below sea level. Due to drought and poor water management, parts of Tehran are sinking by up to 31 cm per year; cracks are appearing in roads, World Heritage sites, and the airport. The current Iranian president has floated the idea of ​​moving the capital, which faces chronic water shortages.

The Financial Times report, citing the scientific study, says that China is a deteriorating hotspot, with nearly half of its cities, including Beijing, heading for subsidence. Mexico City is another capital city heading for a slide. A 2024 research paper estimated that nearly two billion people worldwide live in areas affected by subsidence, calling it a "submergence crisis."

Current warming is exacerbating the risks. Melting permafrost is causing subsidence in Alaska; rising seas are combining with subsiding land to make floods more frequent; and climate-induced drought is exacerbating the demand for more water extraction, causing further destabilization.