Land subsidence, the gradual sinking of land, can significantly amplify the effects of rising sea levels in densely populated coastal regions, according to a new study. The research, published in the journal Nature Communications, highlights that local land sinking can increase the rate of relative sea level rise, exacerbating flooding risks and threatening infrastructure, ecosystems, and communities.
Key Findings of the Study
The study, led by scientists from the University of Hawaii and the University of California, analyzed data from 99 coastal cities worldwide. It found that in many cities, land subsidence rates are higher than the global average sea level rise, making the combined effect much more severe. For example, in parts of Jakarta, Indonesia, land is sinking at a rate of up to 25 centimeters per year, while sea levels are rising by about 3 millimeters annually. This means that relative sea level rise in these areas is much faster than global projections.
Implications for Coastal Cities
Coastal cities like Tokyo, Shanghai, Bangkok, and New Orleans are also experiencing significant subsidence. The study warns that if subsidence continues unchecked, these cities could face increased flooding, saltwater intrusion into freshwater supplies, and damage to infrastructure such as roads, buildings, and ports. The researchers emphasize that reducing groundwater extraction and implementing better land-use planning can help mitigate subsidence.
Global and Local Factors
While global sea level rise is driven by climate change, land subsidence is often a local issue caused by human activities such as groundwater extraction, oil and gas drilling, and soil compaction. The study underscores the need for integrated coastal management that addresses both global and local factors to protect vulnerable communities.
Recommendations for Action
The authors call for improved monitoring of land subsidence using satellite data and ground-based sensors. They also recommend policies to limit groundwater pumping, promote water conservation, and invest in flood defenses. By addressing subsidence, cities can reduce the immediate risks associated with sea level rise and buy time for long-term adaptation measures.
Conclusion
As sea levels continue to rise due to climate change, land subsidence poses an additional and often overlooked threat to coastal regions. This study highlights the urgent need for action to mitigate both global and local factors to protect densely populated areas from the combined impacts of sinking land and rising seas.
