Subsidence in Coastal Cities Throughout the World Observed by InSAR

We measured subsidence rates in 99 coastal cities around the world between 2015 and 2020 using the PS Interferometric Synthetic Aperture Radar method and Sentinel-1 data. In most cities, part of the land is subsiding faster than sea level is rising. If subsidence continues at present rates, these cities will be challenged by flooding much sooner than projected by sea level rise models. The most rapid subsidence is occurring in South, Southeast, and East Asia. However, rapid subsidence is also happening in North America, Europe, Africa, and Australia. Human activity-primarily groundwater extraction-is likely the main cause of this subsidence. Expanded monitoring and policy interventions are required to reduce subsidence rates and minimize their consequences.

Automated summary

We measured subsidence rates in 99 coastal cities around the world between 2015 and 2020 and found that in most cities, land is sinking faster than sea level is rising. This poses a significant threat of flooding to these cities much earlier than predicted by sea level rise models. The most rapid subsidence is occurring in Asia, but it is also happening in other continents. Human activity, particularly groundwater extraction, is believed to be the main cause of this subsidence. Expanded monitoring and policy interventions are necessary to reduce subsidence rates and minimize its consequences.