China is Sinking: Why 45% of Urban Cities are in Danger

**Sanitized Transcript:**

We all know the struggle of rising rents, but what if the ground itself is increasing your housing costs? In China, a significant phenomenon is unfolding: nearly half of urban China, an area larger than Texas, is sinking. That’s right, megacities and bustling metropolises are slowly disappearing beneath people’s feet. Will millions be forced to become climate refugees in their own country? Or will China find what’s causing this issue and find a solution? Let’s look at what’s causing 45% of China’s urban landscape to sink.

With its massive population of 1.4 billion people, China is facing a concerning problem: the ground under many of its cities is sinking. Recently, the discussion about China’s major cities sinking has gained traction on social media, thanks to a paper published on April 18th in the scientific journal *Science*. The paper, titled “A National Scale Assessment of Land Subsidence in China’s Major Cities,” was put together by a research team led by Zurui Ao, an associate researcher at South China Normal University. Using satellite technology, they measured how the land surface changed in elevation across 82 major cities from 2015 to 2022. The findings are striking, showing that 45% of these cities are sinking faster than 3 millimeters per year, and 16% are going down at a rate faster than 10 millimeters per year, affecting about 270 million people. This issue is not limited to eastern coastal cities; it’s also happening in some northern, western, and southwestern cities.

The paper also makes a worrying prediction. By the year 2120, due to both land subsidence and rising sea levels, around 26% of China’s coastal lands could end up below sea level, impacting about 11% of the coastal population. Zurui Ao pointed out that even though only a small portion of China’s land is sinking, it still poses a significant problem. With China’s urban population being over 900 million, even a little bit of sinking land can create major issues for urban life. This research serves as a wake-up call, showing that sinking land is a serious threat. The combination of subsiding cities and rising seas means that millions of people might have to deal with the consequences much sooner than anyone expected.

Now, consider this happening over a century. If this trend continues, a quarter of China’s coastal land could end up below sea level. What makes this even more concerning is that sea levels are rising due to climate change. So, you have land sinking on one hand and water levels rising on the other—a double challenge. This isn’t some far-off scenario; it’s happening right now, affecting millions of people in China’s biggest cities. The combination of sinking land and rising seas is a real and present danger, demanding serious attention.

But one question remains: why is this happening? Is it just climate change, geographical factors, or other influences we may not even consider? Although the research paper didn’t pinpoint the exact reasons, it suggested that groundwater extraction, heavy buildings, and urban development are likely to blame. Natural factors like the geological environment and bedrock depth also play a role. Interestingly, the paper didn’t explore the issue of excessive groundwater extraction, which seems to be a significant factor. It’s not just an urban problem; the sinking land costs China over 7.5 billion yuan, which is about $1 billion every year.

A senior geological engineer explained that widespread subsidence in urban areas is a big-picture issue. Locally, it might manifest as slow sinking or sudden ground collapses, which can cause significant damage. These collapses occur because when the ground compacts, it can create voids that lose water or sediment, making the ground less stable and prone to collapse. This isn’t just a local issue affecting some parts of China; it’s a national problem, as highlighted by experts.

For example, Tianjin, a northern city with a population of over 15 million, has been significantly affected. Just last year, 3,000 residents had to be evacuated due to a sudden geological disaster caused by water depletion and the construction of geothermal wells. It serves as a reminder of how urban development and resource extraction can lead to serious, unexpected problems.

Back in 2014, research indicated that before ground collapses, there are usually warning signs like subsidence and underground cracks. These signs can help provide early warnings about potential collapses. When the ground sinks, it can lead to various problems: building foundations can settle unevenly, houses can crack, underground pipelines can get damaged, and even well casings can shift. Additionally, it worsens flooding and storm surges, which is a significant concern for any city.

Take what happened on April 18th in Lanzhou City, Gansu Province. There was a serious road collapse and cracking in the area. A local resident reported that the ground collapsed more than a meter deep over an area around 500 meters long, affecting all the storefronts along that street. Since 2019, the neighborhood and nearby roads have been dealing with continuous collapses, even swallowing cars whole in some instances. Buildings have also been impacted, with some collapsing in the neighborhood’s first phase of development.

Lanzhou has experienced a series of subsidence incidents. For instance, in December 2022, similar issues were reported in the Dona neighborhood of Qilihe District. Foundation subsidence has led to cracks and deformations in building walls, causing significant concern for residents. One resident expressed fear about the situation, stating, “It’s affecting our lives. I’m really scared, too, living up here. You see how the bottom of our building has cracked like this. It’s really frightening.” Another added, “The cracks in our building are getting bigger and bigger. We’re really worried about the situation we’re living in.”

In 2016, multiple road collapses occurred in just one day, with cars falling into pits and pedestrians getting injured. Recently, on April 15th, a road collapsed in Hohhot, Inner Mongolia, creating a pit about 10 meters wide and 4 meters deep. Witnesses described hearing the sound of flowing water as the ground gave way. One person recounted a close call, saying, “That bus was parked by the roadside the whole time. Just as it started moving, the ground where it had been parked suddenly collapsed.”

The issues don’t stop at just the ground sinking; it’s about feeling like your world is falling apart. It’s hard to feel safe when your home is cracking, and you can’t even open your door. China’s land subsidence issue isn’t just about rapidly expanding cities; it’s also heavily tied to the country’s old coal mining districts. Overmining has left these areas vulnerable, often forcing authorities to inject concrete into the crumbling mine shafts to prevent further sinking.

However, this problem isn’t limited to China. A study published in February revealed that about 6.3 million square kilometers of land worldwide is at risk of subsidence. Indonesia is among the hardest hit, with significant parts of its capital, Jakarta, now sitting below sea level. Experts have noted that vulnerable cities could learn from Tokyo’s experience, which stabilized after banning groundwater extraction in the 1970s.

A 2022 study from Singapore found that of the 44 major coastal cities suffering from subsidence, 30 are in Asia. This ties the issue closely to urbanization and population growth. As urban density increases, more water is extracted, leading to more subsidence. In a paper published in 2023, researchers identified five major subsiding centers in Hohhot, which sank at an average annual rate of 3.65 millimeters.

Official data released by the Chinese government in 2019 revealed alarming trends. By the end of 2015, over 50 cities at the prefecture level or above in 21 provinces had experienced ground subsidence, double the number compared to 2010. The affected area was massive, with over 12,400 square kilometers experiencing a ground subsidence rate exceeding 50 millimeters yearly.

Among all the sinking cities in China, Tangshan is sinking the fastest, with an average annual sinking rate exceeding 52 millimeters. The World Meteorological Organization noted that the average annual sea level rise from 2013 to 2022 was 4.62 millimeters. If the sinking rate in Tangshan and the sea level rise rate remain unchanged, large areas along its coast could be underwater in just 50 years.

Fast forward to May 31st, 2023, and more trouble hit Tangshan. Several high-rise apartment buildings in the Country Garden neighborhood suddenly started sinking, tilting, and experiencing foundation cracking. The situation was so dire that over 3,800 residents had to relocate urgently. This was due to long-term excessive groundwater extraction.

Monitoring data from a well near the Country Garden neighborhood showed that the water level dropped significantly over the years. Experts have identified excessive extraction of underground hot water from limestone formations as a major cause of the decrease in regional water levels. The limestone formations have weakened due to the drop in groundwater pressure, leading to collapses and sinking.

China’s capital isn’t safe either. A study published in May 2022 revealed that Beijing also has massive groundwater depression funnels, and the whole city is sinking. From April 2010 to December 2019, the subsidence rate in Beijing varied significantly. The main trouble spots are in Chaoyang District and Tongzhou District, with some subway lines experiencing serious deformation.

Shanghai has been sinking since 1921, with experts estimating it has dropped by more than 2 meters. Global warming is exacerbating the issue, as rising sea levels along the Shanghai coast contribute to subsidence. Xi’an, in central China, is also experiencing significant subsidence, with ancient structures like the bell tower and Big Wild Goose Pagoda showing signs of tilting.

The primary cause of this subsidence crisis is human activity, particularly the excessive extraction of groundwater for various uses, including agriculture and urban development. The accelerated urbanization process has led to increased demand for water, resulting in significant groundwater depletion.

To address these challenges, China must implement strict regulations on groundwater extraction, invest in alternative water sources like desalination, and crack down on illegal pollution and construction practices. Encouraging responsible urban planning and improving monitoring systems will also be essential in mitigating the impacts of land subsidence.

Collaborating with international partners could further enhance efforts to tackle groundwater depletion and subsidence challenges on a global scale. By sharing knowledge and resources, countries can work together to develop innovative solutions to address the root causes of land subsidence.