Chinese Cities Are Sinking Rapidly (npr.org) 69
An anonymous reader quotes a report from NPR: Major cities across China are sinking, putting a substantial portion of the country's rapidly urbanizing population in harm's way in the coming decades, according to a sweeping new analysis by Chinese scientists. Subsidence is the technical term for when land sinks relative to its surroundings, and it's a major threat for cities around the world. It accelerates local sea level rise from climate change, because the land is getting lower as the ocean gets higher. Urban subsidence can also affect inland cities by damaging buildings and roads, and causing drainage issues when water is trapped in sinking areas.
Out of 82 major Chinese cities, nearly half are measurably subsiding, according to the new study, which was published in the journal Science and conducted by more than 50 scientists at Chinese research institutes. The areas that are sinking are home to nearly one third of China's urban population. And the authors estimate that about a quarter of China's coastal land will be below sea level in the next hundred years, largely due to subsidence. That means tens of millions of people are already at risk, and that could grow to hundreds of millions if China's cities continue to both grow in population and subside at their current rate, and seas continue to rise. Oceans are rising steadily due to greenhouse gas emissions from burning oil, gas and coal.
This is the first time scientists have used satellite data to systematically measure how much cities are sinking across China. The study measured how much cities subsided between 2015 and 2022. Similar recent studies in Europe and the United States have also found significant subsidence in some cities, but didn't show the same widespread sinking that is present across China. "The places that really have high levels of subsidence are Asia," says Nicholls, who was one of the authors of a recent study that analyzed sinking cities across the U.S. Asia is at higher risk, he says, because many Asian cities are built on river deltas that are prone to sinking when you put heavy buildings on top and pump groundwater out from below. The places that are sinking most rapidly in the U.S., such as New Orleans, share that geology.
Out of 82 major Chinese cities, nearly half are measurably subsiding, according to the new study, which was published in the journal Science and conducted by more than 50 scientists at Chinese research institutes. The areas that are sinking are home to nearly one third of China's urban population. And the authors estimate that about a quarter of China's coastal land will be below sea level in the next hundred years, largely due to subsidence. That means tens of millions of people are already at risk, and that could grow to hundreds of millions if China's cities continue to both grow in population and subside at their current rate, and seas continue to rise. Oceans are rising steadily due to greenhouse gas emissions from burning oil, gas and coal.
This is the first time scientists have used satellite data to systematically measure how much cities are sinking across China. The study measured how much cities subsided between 2015 and 2022. Similar recent studies in Europe and the United States have also found significant subsidence in some cities, but didn't show the same widespread sinking that is present across China. "The places that really have high levels of subsidence are Asia," says Nicholls, who was one of the authors of a recent study that analyzed sinking cities across the U.S. Asia is at higher risk, he says, because many Asian cities are built on river deltas that are prone to sinking when you put heavy buildings on top and pump groundwater out from below. The places that are sinking most rapidly in the U.S., such as New Orleans, share that geology.
How fast are they sinking? (Score:5, Interesting)
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If you dig down below the surface of any European city, you will find the remains of older versions of that city underneath it. This is nothing new.
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How many Troys atop each other? How many Jerichos? Use the city until it becomes unusable and start over, nothing is permanent.
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I'm sure cities 500+ miles inland have to worry about sea level rise. Read TFA at least.
Again, nothing is permanent. Sea levels have risen above the current value and fallen way below it.
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I understand from working geologists in soil districts and the like that actions can be taken on a building by building basis, but can you apply that to an area?
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Or, you do like areas like the Netherlands or New Orleans, and you build yourself a big ass levee system to keep the ocean at bay (no pun intended).
Overall, in a battle between nature and man....nature will eventually win.
But, man CAN hold out for a long time...I mean New Orleans just recently had it's 300th anniversary, you know?
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What? No. Some things are new. LOTS of things are new.
You can build brand new cities in places where no cities have ever been placed. That's actually VERY easy to do. What's difficult is building very heavy cities very quickly in very wet areas.
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Cities build layers as the constructions degrade/erode and new stuff is built on top of that. There may or may not be sinking going on, but cities are generally rising on top of previous settlements. linky [newspire.net]
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I read this article in the news yesterday. Much of the world is sinking. It's often measured in millimeters. Tokyo sank 15 inches (just short of half a meter) one decade. That's orders of magnitude different. A few millimeters per decade is manageable. A meter per decade is not.
According to the study, "we provided a systematic assessment of land subsidence in all of China’s major cities from 2015 to 2022. Of the examined urban lands, 45% are subsiding faster than 3 millimeters per year, and 16% are subsiding faster than 10 millimeters per year, affecting 29 and 7% of the urban population, respectively."
So, not a meter per decade but per century. How significant that is depends on the numbers of people and infrastructure affected. This study claims that the affected people an
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The difference is that in the West the cities grew at a slower rate and so the sinking was more gradual while having time to find other water supplies. Chinese cities grew too fast, finding the exact same problems the West had but in a shorter time frame.. Now they get to deal with the problem if deciding if all the water goes to the new cities or if it continues to go to farmers, because there's not enough to go to both.
Population growth, or crash? (Score:5, Insightful)
FTA: "That means tens of millions of people are already at risk, and that could grow to hundreds of millions if China's cities continue to both grow in population and subside at their current rate, and seas continue to rise."
Uhhh...China's about to enter a population collapse the likes of which the world has NEVER SEEN. The cities may be sinking, but I don't think that population growth is a problem they need to worry about.
Re:Population growth, or crash? (Score:5, Insightful)
The pop. of China can decrease while the pop. of their cities can increase. People move and with the desertifcation going on in China, this will likely continue.
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You're a hundred percent correct in a general sense. However, given the massive scale of the population collapse https://www.pewresearch.org/sh... [pewresearch.org] it does seem to me that urban populations are bound to see a significant reduction as well. Going by mid range estimates they're projected to lose almost 35% of their population by 2100.
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Oddly enough, the US population is expected to decline by about the same amount... If you exclude immigration, which is what they seem to have done for China.
https://www.census.gov/newsroo... [census.gov]
They are assuming that nothing much will change in China, but that seems unlikely. If the government was willing to have a one child policy, encouraging children should be no big deal.
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If the government was willing to have a one child policy, encouraging children should be no big deal.
It turns out it is a big deal to encourage people to have children. China's one child policy has been in place from 1979 to 2015, that's long enough that the culture has changed on what it means to have more than one child. You'll have an entire generation that don't know what it means to have siblings, and have no idea what it means to manage more than one child at a time.
Consider some basic logistics of having more than one child. If there's one child then there's a bedroom for the parents and one for
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China builds entire cities in advance of expected migration. I'm sure they can supply larger homes and schools etc.
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First-world cou
Worry about the infrastructure going underwater (Score:3, Insightful)
People aren't addressing the fact that when the infrastructure goes under it will pollute and cause blockage to the coasts.
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People aren't addressing the fact that when the infrastructure goes under it will pollute and cause blockage to the coasts.
Yep. There's tons of highly polluted properties on coasts, including refineries, fuel depots, shipyards, storage yards... Even if you removed the buildings and whatnot completely the soil would still be contaminated. And then there's the nuclear plants... Over 40% of them are coastal worldwide, and that number rises to 66% if you count plants under construction.
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I wouldn't bank on it happening. If China has proven anything, it's that it's good at infrastructure programmes.
How big is the ocean? (Score:1)
It accelerates local sea level rise from climate change, because the land is getting lower as the ocean gets higher.
Isn't the ocean, like... big?
I thought the pacific ocean was like, half the planet? And a couple of miles deep?
How far down are these cities sinking?
Re:How big is the ocean? (Score:4, Informative)
For reference, Shanghai has sunk 3 meters [bbc.com] in the past 100 years.
China has a long history of dealing with subsiding land, with both Shanghai and Tianjin showing evidence of sinking back in the 1920s. Shanghai has sunk more than 3m over the past century.
Golly (Score:1, Troll)
accelerates local sea level rise from climate change, because the land is getting lower as the ocean gets higher.
Gotta tie it into global warming somehow.
This particular issue has nothing to do with it, and is at a faster rate. River deltas meander back and forth (like rivers themselves). As such, they are constantly depositing fresh silt, back and forth, back and forth.
Build a city, put in levees to guide the river, and this process stops. The weight of the city and the silt it is built on slowly squeeses out water, squeezes it down. New Orleans is 6 feet below sea level, as we found out 20 years ago.
The process
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Gotta tie it into global warming somehow.
This particular issue has nothing to do with it, and is at a faster rate.
Wrong. It is not the cause of Global Warming, and it is not caused by Global Warming. So far you would be right. But it is a problem whose consequences get worse due to Global Warming. So yes, it has to do with Global Warming.
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Gotta tie it into global warming somehow.
This is the funniest contrarian take I've seen today. I could easily respond with "gotta discredit any reference to global warming somehow". Would you have rather they said "accelerates local sea level rise from some unnamed phenomenon"? Are you disagreeing with the measurable fact that the sea level has risen as a direct result of rising temperatures, or are you simply bothered by the term "global warming" because you view any reference to it as some plot to sell you something or get someone elected?
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They are orders of magniude difference in speed. The "combined problem" of delta subsidence AND OH MY GOT GW SEA RISE is the most distorting thing since CNN ran a story with the headline "global warming sea rise will be just like the tsunami" which killed 300,000 people.
Clicking on the link, 6 paragagraphs down, they say it will be 30 feet, "like the tsunami", but over 300 years.
So learn 2 hyperbole like your power broker masters. You only think I disbelieve. Because you don't think.
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Err....we've knows NOLA was below sea level for many MANY years....decades....a century or more even.....
What we found out with Katrina was...that the US Army Corps of Engineers had made some serious mistakes and short cuts in the levee system they had built and overrated.
This isn't something new to man....go ask those nice folks in the Netherlands that fight off the ocean like we do here....they know a thing of two about living below se
Re: Golly (Score:2)
"What we found out with Katrina was...that the US Army Corps of Engineers had made some serious mistakes and short cuts in the levee system they had built and overrated."
That is far from the most important thing we found out. For example, deforestation was predicted to make storm surges worse and what happened was exactly in line with those predictions.
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A climate story consistent with geology! (Score:2)
I'm very happy to see a "climate change" article that is consistent with geologic facts, that is an excellent development. Land subsidence is naturally occurring and happens all the time, but it can be significantly accelerated by draining aquifers, which lowers the water table and compacts the soils. This is definitely a direct consequence of urbanization, especially in arid climates.
Subsidence is typically quite localized, if by "localized" we mean an entire geographic region. For example, all of the land
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EU must get involved (Score:2)
The EU needs to pass a law, making it illegal for China's territory to sink. This is the way!
The NPR article does not mention "rapidly"... (Score:2)
... sinking Chinese cities. Maybe that's in the linked Science article (which I can't access).
So.... not global warming? (Score:1)
The fine article points out that the cities are built on silt and with the pumping out of drinking water from beneath the city the cities are sinking in the mud. Seems to me like the cities have a problem with sinking into the sea regardless of how much the sea level rises. Not only that there's a mention that they might be able to reverse the process by pumping water back under the city.
So, first, the rate of the cities sinking into the sea is something like an inch per year so clearly something that the
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Desalination has serious drawbacks. If you chuck the resulting brine back into the ocean you create a massive dead zone.
You apparently missed the part where the brine was pumped under the city. If the brine isn't dumped into the sea then it's not going to create some dead zone in the sea.
And rather than create yet more waste with nuclear, just use solar/wind since created fresh water can be easily stored - the intermittent nature of renewables isn't an issue.
Fine, whatever, use wind and solar power instead, the point is that they already recognized the cause of the cities sinking into the sea so they know how to reverse the process. Pumping water back under the city would be expensive so there would be a matter of how to pay for it. Freshwater is valuable so the funding of pumping water under
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Why is this an issue? Solved problem. (Score:2)
Lots of the Netherlands sits below sea level.
So why should we be concerned even slightly about cities subsiding when we already can easily deal with places that exist many meters below sea level?
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Look out! The sky is falling! Didn't you get the memo?
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Ounce of prevention vs pound of cure etal.
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Because it costs trillions of dollars to retrofit a city?
Source? Billions at worst. Like I said, this is a solved problem, and places like Amsterdam have solved this for way less than "Trillions".
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Far cheaper to work to prevent it from coming to pass.
Removal of ground water (Score:2)
now counts towards Global Warming. Good to know.
No problem (Score:2)
Sea walls are a thing (Score:2)
The Netherlands have proven without question that you can build and maintain sea walls for centuries at marginal cost to the economy. Building a seawall is very straightforward and a seawall of any length can be built in under a decade.
Any engineers here know anything about seawalls? (Score:2)
You're correct the Dutch do a good job with this. Then I think of this https://www.santacruzsentinel.... [santacruzsentinel.com] where protecting San Francisco all by itself with sea walls and whatnot is projected to cost over a hundred billion.
I'd be curious to hear from engineers familiar with this type of thing in regards to what the Dutch are doing versus something like what's being projected around SF.
Re: Any engineers here know anything about seawall (Score:2)
That's for the entire bay, though? San Francisco the city only needs about 14 miles of seawall. Then it's another 50+ miles to San Jose, and 65+ miles up to Richmond point. I would imagine each city will tackle the problem different as they're in different counties, different soil types and most importantly different elevations
Re: Sea walls are a thing (Score:2)
Oh look, it's the "it's to hard qq" crew. Go back home nobody needs your doomer shit
Much overlooked, and not just in China (Score:2)
In all the arguments over climate change and shouting about rising sea levels, most people have completely ignored some rather basic science and statistics. If you look at a country like the USA with a map that shows population density, you see that a huge portion of the population has concentrated itself next to the water. It's understandable - it's often much nicer there. Given that such areas are quite pleasant, a lot of the more affluent like to be there, and the companies they run tend to be there. Thi
No Big Deal. (Score:2)
People, lives, communities are not significant in China. Don't get me wrong... their importance in other countries is always less than advertised. But they especially do not matter to the centralized powers in China. So the subsidence isn't on the list of things to worry about. When it truly becomes a problem, the expectation will be that those affected will just move.
Mayday! Mayday! We are sinking! (Score:2)
https://www.youtube.com/watch?... [youtube.com]