Subsidence Poses Threat to China’s Major Cities Amid Climate Change
Nearly half of China’s major cities are experiencing subsidence, a phenomenon where land sinks due to excessive groundwater extraction and the weight of sprawling urban areas. This subsidence poses a significant risk of flooding, particularly as climate change accelerates sea level rise.
According to a recent study published in a scientific journal, over 920 million people, or two-thirds of China’s population, reside in urban areas experiencing moderate to severe subsidence. Subsidence can cause severe damage to infrastructure and lead to catastrophic flooding, especially in coastal regions.
Experts warn that by 2120, up to 26 percent of China’s coast could be affected by subsidence, impacting millions of people. To mitigate this threat, a combination of subsidence reduction and adaptation measures, such as improved groundwater management and coastal defense systems, are crucial.
In cities like Tokyo and Osaka, successful efforts to reduce groundwater usage have slowed subsidence rates. Shanghai has also made progress in managing subsidence, although it continues at a slower pace.
In coastal areas where subsidence cannot be mitigated, adaptation measures, such as dike systems and land abandonment, may be necessary. However, retreat or abandonment of land is considered unlikely in China due to its high population density and economic development.
Climate Change Exacerbates Subsidence Risk
Climate change intensifies the threat of subsidence by accelerating sea level rise. As sea levels rise, coastal regions become more vulnerable to flooding and the effects of subsidence are amplified.
Experts predict that sea levels could rise by 15 to 20 feet in the coming century, requiring significant investments in sea walls and other coastal defense measures. Orrin Pilkey, a professor emeritus of geology and ocean sciences at Duke University, warns that coastal areas, including China’s, face a severe crisis in the future.
To address the complex challenges posed by subsidence and climate change, a comprehensive approach that combines mitigation and adaptation strategies is essential. By implementing measures to reduce groundwater extraction, investing in coastal defense systems, and planning for future sea level rise, China can work to minimize the risks and protect its population and infrastructure.
