Researchers report that almost half of China’s major cities are experiencing sinking issues | Global News

Nearly half of China’s major cities are facing a critical issue of subsidence, as revealed by a recent study using nationwide satellite data. This alarming trend is putting millions of people at risk of flooding, especially with the rising sea levels.

The study, published in the journal Science, found that 45% of China’s urban land is sinking at a rate faster than 3 millimeters per year, with 16% sinking at a rate exceeding 10 mm per year. This subsidence is attributed to declining water tables and the weight of the built environment.

With China’s urban population already exceeding 900 million, the researchers warn that even a small portion of subsiding land could pose a significant threat to urban life. The cost of subsidence in China is already over 7.5 billion yuan annually, and within the next century, nearly a quarter of coastal land could be lower than sea levels, endangering hundreds of millions of people.

The northern city of Tianjin, home to more than 15 million people, was identified as one of the worst-hit areas. Last year, 3,000 residents were evacuated due to a “sudden geological disaster” caused by water depletion and construction activities.

This issue is not unique to China, as a separate study highlighted that around 6.3 million square kilometers of land globally are at risk of subsidence. Countries like Indonesia, with parts of Jakarta now below sea level, are also facing similar challenges.

Experts emphasize the need for serious mitigation efforts and adaptation strategies to address subsidence, highlighting the importance of learning from past experiences like Tokyo’s successful ban on groundwater extraction in the 1970s. As urbanization and population growth continue, the threat of subsidence remains a pressing concern for many coastal cities worldwide.