Satellite Data Reveals a Third of China's Urban Population at Risk Due to Land Subsidence

A recent study using satellite data has found that about a third of China's urban population, potentially affecting 55 to 128 million residents by 2120, is at risk due to land subsidence. The research, published in the journal Science, studied 82 cities including Beijing, Tianjin, and Shanghai, with a collective population of nearly 700 million people.

The study found that 45% of the urban land area analyzed was sinking, with 16% sinking at a rate of 10 millimeters per year. Hotspots include Beijing and the coastal city of Tianjin. The researchers estimate that 270 million urban residents could be affected, with nearly 70 million experiencing rapid subsidence of 10 millimeters per year or more.

The land subsidence is primarily driven by groundwater withdrawal and can reinforce climate change and sea level rise, especially affecting coastal cities. The researchers caution that not accounting for land sinking in adaptation and resilience plans could risk destruction of lives and infrastructure in the coming decades.

Why this matters: The widespread land subsidence in China's cities poses a significant threat to critical infrastructure and the lives of millions of residents. Addressing this issue requires a collaborative national and global response to mitigate the risks through robust urban planning and infrastructure resilience strategies.

Coastal cities like Tianjin are particularly vulnerable as subsidence reinforces the impacts of climate change and sea-level rise. The researchers call for a national response to address this widespread problem, which also affects cities outside of China, and emphasize the need to move from measurement to understanding the implications and supporting responses.

The main driver of land subsidence is groundwater withdrawal, combined with the weight of buildings and geological factors. Addressing this issue requires moving from measurement to understanding the implications and supporting responses to mitigate the risks. The researchers warn that this could be catastrophic without a strong societal response, as land sinking can reinforce climate change and sea-level rise, particularly affecting significant coastal cities.

Key Takeaways

• 1/3 of China's urban population at risk of city sinking by 2120.
• 45% of urban land area analyzed was sinking, 16% at 10mm/year.
• Groundwater withdrawal and climate change are primary drivers of subsidence.
• Coastal cities like Tianjin are particularly vulnerable to subsidence and sea-level rise.
• Addressing this issue requires national and global response to mitigate risks.