NASA shares alarming map of US sinking cities: Millions at risk; urgent action needed

A new NASA-led study has revealed a hidden but growing threat to millions of Americans living in coastal cities. Land in several urban areas is sinking at rates faster than sea level rise, compounding the risk of flooding and infrastructure damage. Using high-resolution satellite radar data collected between 2015 and 2023, scientists have identified key hotspots where the ground is subsiding significantly. The study warns that without urgent mitigation measures, millions of residents could face severe impacts from flooding, property loss, and economic disruption, highlighting the critical need to include local land motion in climate and coastal planning.The research, published in Science Advances and conducted by NASA’s Jet Propulsion Laboratory, Caltech, and NOAA, shows that some of California’s lowest-lying coastal regions could experience relative sea level rise of over 17 inches by 2050. Certain areas are sinking at more than 0.4 inches (10 millimeters) per year, accelerating the risks posed by climate-driven sea level rise. Lead author Marin Govorcin emphasized that in many reclaimed and urbanized areas, local land motion exceeds sea level rise itself, making traditional flood risk models insufficient.The study highlights multiple regions where land subsidence is particularly severe. Coastal urban areas, especially in the San Francisco Bay Area, Los Angeles, and San Diego, are experiencing accelerated sinking. The phenomenon is driven by groundwater extraction, oil and gas drilling, and soil compaction—activities linked to decades of urban and industrial development. These factors increase uncertainty in future flood projections and complicate planning for infrastructure and disaster management.Beyond natural geological processes, human activities play a major role in amplifying subsidence. Excessive groundwater pumping, urban development, and hydrocarbon extraction are accelerating vertical land motion in already vulnerable regions. In some parts of Los Angeles and San Diego counties, these factors could contribute up to 15 additional inches of local land motion over the coming decades, highlighting the need for sustainable resource management alongside climate adaptation.NASA’s findings underline the importance of incorporating vertical land motion into sea level rise assessments. Without accounting for subsidence, existing flood models may underestimate risks, leaving millions of residents, businesses, and ecosystems exposed. The study calls for urgent coastal management strategies, improved urban planning, and adaptive infrastructure investment to protect communities from the compounded effects of sinking land and rising seas.As millions of Americans live in coastal zones, these insights serve as a wake-up call for policymakers, planners, and residents. Mitigation measures such as regulating groundwater use, reinforcing vulnerable infrastructure, and updating flood models are essential to minimize the devastating impacts of sinking cities. Without prompt action, the combination of subsidence and rising seas could transform familiar urban landscapes into disaster-prone areas within decades. Scientists stress that the window for effective action is rapidly closing. The choices made today will decide whether coastal cities adapt—or are lost to the sea.