Major coastal cities are sinking faster than sea levels are rising

Other research has shown that global warming is melting ice around the world and sea levels are rising as a result. This worries the cities that are on the coasts. However, that is not the only problem.

Major coastal cities are sinking

In the article published in the journal Nature Sustainability, a group of researchers revealed that several coastal cities around the world are sinking faster than the sea level is rising. Through satellite radar, they measured the subsidence of the ground in 47 cities during a period of time from 2014 to 2022.

Some of the cities were Lima (Peru), New York (United States), Barcelona (Spain), Tokyo (Japan), Istanbul (Turkey), Alexandria (Egypt), Bombay (India), Luanda (Angola), Buenos Aires ( Argentina) and Rio de Janeiro (Brazil).

In the new study, scientists found that sea level rise combined with land subsidence could spell major trouble for coastal cities in years to come.

As a result, they found that almost all cities exhibited some degree of land subsidence. And 44 of them were sinking at a rate faster than the sea rises. The one that presented the most alarming figure was Ho Chi Minh (Vietnam) with 16.2 mm/year. To give you an idea of gravity, the global average increase is 3.7 mm/year.

Global average sea level rise is 3.7 mm/year

The 48 cities surveyed as part of the NTU study were selected based on a minimum population of five million in 2020 and located within 50 kilometres of the coast. A comparison of coastal cities around the world shows that the fastest rates of relative local land subsidence are concentrated in Asia, especially Southeast Asia.

Land subsidence varies at the neighbourhood and even block level, but in the 48 cities surveyed, the team found an average subsidence rate of 16.2 millimetres (mm) per year, while some of them have land that is sinks at 43 mm per year. The current global average sea level rise is 3.7 mm/year. Coastal cities experiencing notable land subsidence at rates greater than 20mm per year include Tianjin (China), Ho Chi Minh City (Vietnam), Chittagong (Bangladesh), Yangon (Myanmar), Jakarta (Indonesia), and Ahmedabad (India).

The findings are an example of groundbreaking research that seeks to address humanity's grand sustainability challenges and accelerate the translation of research discoveries into innovations that mitigate human impact on the environment.

“Rapid land subsidence is frequently caused by groundwater extraction,” Tay said. "This is worrying in Asia, where many coastal cities are now centers of growth and their high demand for groundwater extraction to meet the water needs of growing populations."

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