Sources: All information stated in this article is based on reliable information, and is summarized at the end of this article.
The area with an average annual settlement rate faster than 3 mm/year accounted for 44.7%, and the area with an average annual settlement rate faster than 2 10 mm/year accounted for 15.8%.
Experts say that by 2120, up to 26% of China's coastal cities will be below sea level.
In addition, due to global warming, it may directly affect 275 million people.
In the next century, nearly a quarter of coastal land will be below sea level, and nearly 300 million people will be homeless?
"Urban sinking" has become an international problem
"Urban sinking", which sounds only magical, only appears in the scene of science fiction movies, has been included in the academic topics of many researchers, and a recent article from an international academic journal "Land subsidence assessment of major cities across the country" has detonated the topic of the topic.
Researchers from 28 institutions, including the Center for Ecological Research of Peking University, used satellite remote sensing data to evaluate the degree of land subsidence in 82 large and medium-sized cities across the country.
The area of the city is sinking much faster than expected.
The proportion of urban areas with an average annual subsidence rate of more than 3 mm/year alone is 44.7%, and the proportion of areas with an average annual subsidence rate faster than 10 mm/year has reached 15.8%.
Cities are sinking, their area is declining, and they are "disappearing" at an average rate of a few millimeters every year, so where will the cities of the future go?
The report's assessment predicts that up to 26 percent of China's coastal cities will be below sea level by 2120.
What sounds like a worrying result is actually playing out around the world.
In 2023, foreign media reported in the magazine "The Future of the Earth", saying that New York will subside an average of 1 to 2 millimeters per year.
And this is only the average data of subsidence in New York, some areas have a large burden, and the subsidence will be greater, such as the lower Manhattan in the United States, the average annual subsidence rate reaches 4.5 mm.
It may sound like a small number, but according to American researchers, parts of New York City will be inundated by rising sea levels, and even more bluntly, the sea level around New York City is rising more than twice as fast as the global level.
New York is still subsidencing at an average rate of a few millimetres per year, and in many other parts of the world, there are even cases of "a few centimetres of subsidence" on average.
As the capital of Indonesia, Jakarta is considered to be one of the fastest subsidence cities in the world.
The rate of subsidence in Jakarta has shifted from about 2 to 5 centimeters per year to 10 centimeters per year.
At this rate, 27% of Jakarta will be completely submerged by 2025.
North America, Europe, Africa and Australia have also begun to subside to varying degrees, with at least 33 of them falling by more than 1 centimeter per year, which may seem light, but it is five times the rate of sea level rise.
That's strange, how do different cities in different countries around the world do it, and how do they "meet together" to settle down to varying degrees?
Is the city saved?
The number one issue is climate.
Global warming has become the consensus of the world, and despite the efforts of countries around the world, judging from the key words put forward at the United Nations climate conferences held in recent years, "warming" is still a problem of continuous development.
Even the statement of "3 degrees Celsius" has been expected by the academic community.
Global warming of 3 degrees Celsius has already affected hundreds of millions of people, and a research institute in the United States said that it will directly affect 275 million people, especially in densely populated Asian metropolises.
In addition, the compaction of natural sediments, "heavy loading" is a factor that cannot be ignored.
In New York, for example, 1,084,954 buildings are built on 777 square kilometers of land, and the total weight of these buildings is about 762 million tons, which is equivalent to 1.9 million fully loaded Boeing 747-400 aircraft parked in the entire city.
Even these calculations do not include the weight of concrete, rebar, glass, etc., nor do they take into account the fixtures, fittings, and furniture in the building, as well as the weight of New York's approximately 8.5 million people.
The pressure on the ground has suppressed the "breathlessness" of the surface layer.
Is the surface so fragile? In fact, the weight is carried above the surface, and the ground is "emptied" from the surface.
The extraction of groundwater, the extraction of oil and gas, etc., are all gradually impacting the forces beneath the earth's surface, and the groundwater appears to be pumped for drinking and other purposes, and the overexploitation of oil and gas is also weakening the surface structure.
Coupled with the accumulation of urban population weight, it is inevitable that the city "cannot hold on".
The cause and effect of global warming and accelerating sea level rise have also become a vicious circle.
As early as 2021, a team of researchers in Spain conducted model tests, which showed that by 2040, nearly one-fifth of the world's population will face subsidence, underground water storage, surface area will be greatly impacted, buildings will be destroyed, and so on.
The next step would be to bring the surface elevation closer to sea level, making cities vulnerable to flooding.
Today, places such as Jakarta and Java have been flooded by seawater, and the safety of the city is in jeopardy.
If as many as 26% of China's coastal cities are expected to fall below sea level by 2120, and nearly 300 million people will live as a result of global warming, is there no remedy?
In fact, in 2012, the British newspaper The Guardian reported that the Shanghai government had already begun to deal with the hidden dangers of flooding, building the country's largest deep drainage system.
In addition, the "Comprehensive Land Subsidence Prevention and Control Plan" (2011-2020) issued by the mainland clearly proposes to promote land subsidence in key areas in North China, Chang Triangle and other regions.
As the American professor said, it may be too late to strengthen groundwater management, build and maintain flood control measures, and restore natural coastal wetlands.
Resources:
More than a million buildings are "pressing", and New York is sinking - Jiefang Daily, CNKI
Research says that nearly half of China's big cities are sinking! How to save our homeland?—— Yangcheng faction