Shanghai streets flooded after heavy rain on July 21, 2023 - Photo: AFP
According to the South China Morning Post on October 17, a new study published in the journal Nature warns that China is facing a "double threat": land subsidence and sea level rise, the fastest in 4,000 years, which could cause severe flooding in economic centers such as Shanghai, Shenzhen, and Hong Kong.
A research team comprising scientists from the UK, the US, and China stated that China's major cities are concentrated in coastal delta regions, which are favorable for economic development but highly vulnerable to climate change.
These areas were formed from thick, soft layers of sediment, causing the ground to naturally subside.
"It is highly likely that the average rate of global sea level rise since 1900 has exceeded any centennial rate in at least the last 4,000 years," the research team said. According to the data, the average rate of sea level rise is currently around 1.5 mm/year.
Scientists say that 94% of the current rapid urban subsidence is caused by humans, mainly due to excessive groundwater extraction, which causes land to sink faster than normal.
Shanghai has been experiencing land subsidence since 1921. By the 1960s, when groundwater extraction reached 200 million tons per year, the ground was sinking by as much as 10.5 cm annually.
Meanwhile, climate change is causing the oceans to absorb heat and expand, combined with melting ice in Greenland and Antarctica, leading to a rise in global sea levels.
According to Lin Yucheng, a researcher at Rutgers University (USA), some areas of Shanghai have subsided by more than 1 meter in the past century due to excessive groundwater extraction, at a rate many times faster than the current rate of sea level rise.
He warned that even a rise in sea level of just a few centimeters would increase the risk of flooding in delta regions, which are home to many industrial areas and global manufacturing centers.
"If a natural disaster occurs here, the international supply chain will be severely affected," he said.
However, while Shanghai has slowed its subsidence rate thanks to strict management of groundwater extraction, other cities such as Jakarta, Manila, and New York face similar risks because they are located in low-lying coastal areas.
Another study published in June also indicated that the severe subsidence in Shanghai has spread to industrial and coastal areas over the past 30 years, but the rate of subsidence has slowed thanks to measures such as pumping in additional groundwater. It is estimated that China loses approximately $1.5 billion annually due to subsidence, with Shanghai alone losing more than $3 billion between 2001 and 2020.
Source: https://tuoitre.vn/thuong-hai-tham-quyen-doi-mat-nguy-co-chim-vi-dat-lun-va-nuoc-bien-dang-20251018105338648.htm
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