"Alarming Sinkage: China's Major Cities in Rapid Decline"
As the world grapples with the devastating impacts of climate change, a new scientific study has revealed a startling reality unfolding in China – nearly half of the country's major cities are sinking, with some doing so at an alarming rate.
The research, published in the prestigious journal Science, paints a sobering picture. According to the study, a staggering 16% of China's urban areas are sinking rapidly, at a rate exceeding 10 millimetres per year. An even larger swath, roughly 45% of the mapped regions, is experiencing a "moderate" rate of subsidence, greater than 3 millimetres annually.
The affected cities span a diverse geographic landscape, from the coastal megalopolises to the inland hubs of the southwest. Even cities like Kunming, Nanning, and Guiyang, which are not as densely populated or industrialized as others, are grappling with this alarming issue.
"Subsidence is certainly not only a problem in China. Many other parts of the world share the same problem," says Ding Xiaoli, a geodesist at the Hong Kong Polytechnic University. Indeed, the study notes that by 2040, almost one-fifth of the world's population is projected to be living on sinking land, with the Netherlands and Jakarta facing particularly severe challenges.
The researchers attribute this alarming trend to a complex interplay of natural and human-driven factors, including groundwater depletion, the weight of buildings, and underground mining activities. Excessive groundwater extraction, in particular, has been identified as a key driver of land subsidence in cities across the globe.
The implications of this phenomenon are nothing short of staggering. The study estimates that within a century, one in ten residents of China's coastal cities could find themselves living below sea level, as a result of both land subsidence and the relentless rise of global sea levels. In fact, the researchers project that a quarter of China's coastal lands could slip below the waterline within just a few decades.
This "double whammy" of sinking land and rising seas poses a grave threat to the hundreds of millions of people who call these vulnerable regions home. Flooding, infrastructure damage, and even entire communities being submerged are all very real possibilities.
Yet, the study also offers a glimmer of hope. The experience of cities like Tokyo and Shanghai, which have successfully slowed their rates of subsidence through regulatory measures and environmental controls, demonstrates that with concerted action, this crisis can be mitigated.
"The key to addressing China's city subsidence could lie in the long-term, sustained control of groundwater extraction," the paper asserts. Dike systems and other adaptive measures could also play a crucial role in safeguarding these sinking coastlines.
As the world watches with bated breath, the fate of China's urban centers hangs in the balance. The race is on to find solutions that can preserve the homes and livelihoods of millions, before the ground quite literally slips away beneath their feet.
Source: https://www.nature.com/articles/d41586-024-01149-7
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