In an article published in May in the journal Earth’s Future, researchers are trying to assess how the cumulative mass of the infrastructure of the megalopolis influences its subsidence, a phenomenon caused by soil erosion and human activity.
Geologists have calculated that the million buildings, towers, and skyscrapers in New York represent a total mass of 762 million tons, which exert extraordinary pressure on the soil. That is the equivalent of more than 75,000 Eiffel towers.
Under this force, the cultural and economic capital of the United States, populated by 8.5 million souls, is sinking an average of one to two millimeters per year. In some neighborhoods where buildings have been built on softer or artificial ground, subsidence could even reach 4.5 mm per year, according to the study.
But building fewer concrete, glass and steel towers won’t change that, warns the study’s lead author, Tom Parsons. “The root cause of New York and the East Coast subsidence is tectonic and cannot be stemmed,” explains this American geophysicist.
And this subsidence should accelerate the impact of rising waters caused by global warming and the melting of glaciers. According to the organization Sea Level Rise.org, the water level in New York has risen 23 centimeters compared to 1950 and the municipality predicts that it will rise another 20 to 75 cm by 2050, or even 1, 8 m before 2100 and repeated storms.
In response, the city made the fortification of its 836 kilometers of coastline a priority. A titanic plan of 20 billion dollars, dubbed “climate resilience”, has been launched with Herculean work to protect itself from the waters.
In the south of Manhattan, between the East River and an expressway, the city has been erecting a wall and dikes since 2021, and raises a green space over 4 km. Where Sandy raised the water 2.7m more than 10 years ago.
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