Sea level rise is a well-known threat to coastal cities, but a new study shows that land subsidence is making them even more vulnerable. Scientists at the University of Rhode Island Graduate School of Oceanography, working with the U.S. Geological Survey, used radar images of the Earth’s surface collected from orbiting satellites to measure subsidence rates in 99 coastal cities worldwide. They found that land is sinking faster than sea levels are rising in many of these cities, which could lead to increased flooding sooner than previously projected.
Cities in South, Southeast, and East Asia are experiencing the most rapid rates of subsidence. For example, Jakarta, the capital of Indonesia, is sinking at an alarming rate due to groundwater extraction, leading the government to plan a move of its capital to Nusantara. Other regions are also affected, including New York City, which is sinking between 1 to 4 centimeters per year due to glacial rebound and the weight of its buildings. This further increases its vulnerability to coastal storms, as sea levels are projected to rise significantly by 2050.
In the United States, cities on the Atlantic coast are subsiding due to glacial rebound, albeit at a low rate. However, cities in the Gulf of Mexico, such as Houston and New Orleans, also face subsidence. Governments worldwide are grappling with the challenge of subsiding coastal areas and the growing flooding hazard they present. The researchers emphasize the importance of accounting for subsidence in current planning efforts to prepare for the impacts of rising sea levels.
As the study continues to evolve, the scientists are exploring ways to improve monitoring capabilities, such as using machine learning. They urge city planners, emergency managers, and decision-makers to consider subsidence when making plans to mitigate the effects of rising sea levels in the future. This research highlights the need for proactive measures to address both rising sea levels and land subsidence to protect coastal cities from increased flooding risks.
