Are coastal cities sinking faster than we think? Here’s the shocking reality!

From documentaries to Hollywood movies, the scary depiction of oceans gullping down coastal cities around the world and causing an apocalypse has also sent chills down the spine, but a recent report now indicates that the screen nightmare is slowly turning into a reality. Here’s a recent report that is alarming, and here’s how ocean waters are slowly consuming the coastal cities. Coastal populations worldwide face a double threat from rising waters. While oceans are expanding due to climate change, the ground beneath many densely populated regions is actively sinking. According to a study published in the digital journal of ScienceDaily by researchers from the Technical University of Munich (TUM) and Tulane University published in Nature Communications, this downward movement of land is drastically accelerating the sea level rise experienced by millions of people living near the coast.Faster rises for coastal populationsMore than half a billion people reside in low-lying coastal zones, putting them on the front lines of environmental shifts. The research reveals that people living in heavily populated coastal areas experience an average relative sea level rise of roughly 6 millimeters per year.This rate is almost three times the global coastline-weighted average of 2.1 millimeters per year and nearly double the climate-driven absolute sea level rise of about 3.15 millimeters per year. The primary driver behind this disparity is land subsidence—the gradual sinking of the ground. What causes coastal land to sink?Figuring out why land sinks is tricky because nature and human activity usually team up at the same time. Heavy groundwater pumping, pulling oil and gas from the earth, the natural packing down of young river delta mud, and the crushing weight of growing cities all push the ground downward. At the same time, natural forces like tectonic shifts and the Earth's crust slowly bouncing back after ancient ice sheets melted add to the problem.Lead author Dr. Julius Oelsmann from DGFI-TUM emphasizes that looking only at the ocean misses half the problem. Human activities like excessive resource extraction destabilize the subsurface, compounding the effects of climate-driven sea level rise.Global hot spots and extreme ratesThe crisis varies heavily by region. Population-weighted coastal averages range from 7 to 10 millimeters per year in countries like Thailand, Bangladesh, Nigeria, Egypt, China, and Indonesia. Meanwhile, the United States, the Netherlands, and Italy average around 4 to 5 millimeters per year. Several major coastal cities stand out for rapid sinking:Jakarta: 13.7 mm/year (with some areas dropping up to 42 mm/year)Tianjin: 13.5 mm/yearBangkok: 8.5 mm/yearLagos: 6.7 mm/yearAlexandria: 4 mm/yearConditions can vary drastically even within the same city; for instance, while parts of Jakarta plunge rapidly, other neighborhoods in the city are rising.The exceptionNot all coastlines are sinking. In parts of Sweden and Finland, geological uplift is causing a relative drop in sea level. Known as postglacial rebound, the land in these regions continues to bounce upward after the heavy ice sheets of the last Ice Age melted—moving faster than the sea itself is rising.Hope through groundwater policyWhile some geological causes are out of human hands, groundwater extraction is a factor governments can directly control. Improved water management, strict withdrawal rules, and recharging aquifers can slow or completely stop the ground from sinking, notes Professor Florian Seitz, Director of DGFI-TUM. History shows this strategy works. Tokyo used to sink by more than 10 centimeters a year, with the worst spots dropping 24 centimeters annually, but government rules and alternative water supplies successfully brought those numbers down. A similar effort started in Texas when officials created the Harris-Galveston Subsidence District in 1975 to regulate groundwater pumping and push for water conservation.