Many of China's biggest cities are sinking into the ground, putting them at greater risk from rising sea levels, according to startling new research published in the journal Science.
The findings reveal a growing threat not just to China but to coastal cities worldwide as increased pollution drives up ocean levels, reported the New York Times.
What's happening?
A whopping 16% of China's major cities are estimated to be sinking by over 10 millimeters (close to 0.4 inches) per year, while nearly half are subsiding by more than three millimeters (about 0.1 inches) annually, the study found.
"It's a national problem," Robert Nicholls, climate scientist and civil engineer at the University of East Anglia, told the Times.
Some areas within cities are dropping even faster than others, destabilizing buildings and infrastructure.
Subsidence is driven by factors such as the sheer weight of urban development, as well as the rapid pumping of groundwater that leaves empty pockets underground that collapse over time, as the study noted. The bustling cities of Beijing and Tianjin are among the fastest-sinking, per the Times.
Why are sinking cities concerning?
As cities sink, they become vulnerable to flooding and other threats posed by climbing sea levels. The researchers estimated that land subsidence combined with rising seas could leave a quarter of urban areas in Chinese coastal cities below sea level within 100 years, the Times noted.
This would put homes, businesses, and critical infrastructure at risk, threatening the safety and livelihoods of huge populations. Many people could be displaced or suffer poor living conditions and economic hardship as a result. Fragile coastal ecosystems would also face severe disruption.
Subsidence is often overlooked in climate adaptation plans, according to an expert quoted by the Times, meaning cities may be underestimating their exposure to flooding and failing to protect residents adequately.
Sinking land is also a concern in parts of the United States and other countries.
What's being done about sinking cities?
Reducing groundwater extraction is key to managing subsidence, according to the researchers. The Chinese city of Shanghai has already curbed its sinking by better regulating groundwater use. In Japan, improved groundwater policies have helped stabilize subsidence in Tokyo and Osaka over time, the Times reported.
Some places are experimenting with injecting water back underground to reverse the effects of over-pumping. Coastal cities are also investing in flood protection measures like seawalls and elevated buildings to adapt to higher sea levels.
On a personal level, you can advocate for sustainable groundwater practices in your own community. Supporting policies that prepare for rising seas can also help build resilience.
While subsidence can't be stopped completely, the study shows there are ways to slow it down and adapt as our planet and its cities continue to change. By confronting these risks head-on, we can work to keep our communities above water.
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