Major US Cities Are Sinking Due to Urbanization and Climate Change, Study Finds
Recent satellite radar research has revealed a concerning trend in the United States – the land in major cities is sinking at an alarming rate. This phenomenon is attributed to a combination of urbanization, drought, and rising sea levels, impacting the 28 most populous cities in the country.
According to the study, conducted between 2015 and 2021, at least 20 percent of urban land in every city analyzed has experienced some degree of subsidence. In 25 out of the 28 cities, more than 65 percent of the land is showing signs of sinking.
With a combined population of nearly 34 million people, these sinking cities are facing a gradual but significant threat that needs to be addressed promptly.
Geophysicist Leonard Ohenhen, who has been studying subsidence rates in the US, highlighted the importance of addressing this issue, stating that subsidence is often overshadowed by global sea level rise but plays a crucial role in the increasing water levels along the eastern coast.
The study identified cities like Chicago, Dallas, New York, and Houston as having significant portions of sinking land, with some areas experiencing rapid subsidence rates exceeding 2 millimeters per year. In Texas, cities like Fort Worth, Dallas, and Houston are particularly affected, with an average subsidence rate of over 4 mm per year.
While subsidence rates above 5 mm per year are considered a cause for concern, even lower rates can pose risks to infrastructure integrity, especially if the sinking is uneven across different areas of a city. This can lead to structural damage, including cracks in buildings, roads, and bridges, as well as increased flooding potential.
The researchers estimated that more than 29,000 buildings in major US cities are currently at high risk of damage due to subsidence, highlighting the latent nature of this threat that could lead to catastrophic consequences if left unaddressed.
Houston emerged as the fastest-sinking city among the 28 studied, with over 40 percent of its land subsiding at a rate exceeding 5 mm per year. Factors contributing to this include long-term groundwater extraction and oil and gas activities.
The study suggests that cities can potentially mitigate subsidence by reducing groundwater extraction, but the solution for each city is complex and depends on various factors such as size, geology, and specific threats. Coastal cities may need to focus on protection from rising sea levels, while flood-prone cities may require improved drainage systems.
Ultimately, the goal is to make coastlines more resilient to the effects of subsidence and climate change. By utilizing data from studies like this, cities can better plan for the future and safeguard their infrastructure from the impacts of sinking land.
The findings of this research were published in the journal Nature Cities, emphasizing the urgency of addressing subsidence in major urban centers across the US.
