As if rising sea levels weren’t enough of a concern, add to it the risks facing New York City: the metropolis is slowly sinking under the weight of its skyscrapers, houses, asphalt and humanity itself.
New research estimates that the city’s land mass is sinking at an average pace of 1 to 2 millimeters per year, something known as “subsidence”.
This natural process occurs everywhere as the ground compresses, but the study published this month in the journal Earth’s Future tried to calculate how the enormous weight of the city itself speed up the process.
a million buildings
There are more than a million buildings spread over the five neighborhoods of the city. The research team calculated that all these structures add up to about 1.7 billion tons of concrete, metal and glass -approximately the weight of 4,700 Empire State Buildings- pressing down on the Earth.
The rate of compression varies by city. The skyscrapers of midtown Manhattan are built largely on rock, which compresses very little, while parts of Brooklyn, Queens, and midtown Manhattan are on looser soils and they sink faster, the study reveals.
Although the process is slow, lead researcher Tom Parsons of the US Geological Survey said some areas of the city They will end up underwater.
The ground goes down, the water rises
“It is unavoidable. The ground is going down and the water is rising. At some point, those two levels will meet,” said Parsons, whose job it is to forecast dangerous events, from earthquakes and tsunamis to gradual shifting of the ground under our feet.
But Parsons said there is no need to invest in life preservers yet.
The study is limited to pointing out that the buildings themselves are contributing, albeit gradually, to the modification of the landscape. Parsons and his research team reached these conclusions using satellite imagery, data modeling, and numerous mathematical hypotheses.
they will have to pass hundreds of years – the exact date is unclear – before New York becomes America’s version of Venice, sinking into the Adriatic.
But there are parts of the city that are in more danger.
“There’s a lot of weight there, a lot of people,” Parsons said, referring specifically to Manhattan. “The average elevation in the southern part of the island is only 1 or 2 meters above sea level: It is very close to the water level, so it generates deep concern”.
Since the ocean rises at a rate similar to the land sinking, Earth’s climate change could speed up the times for parts of the city to disappear under water.
“It doesn’t mean we should stop building buildings. It doesn’t mean buildings are the only cause of this. There are many factors“, said Parsons. “The purpose was to highlight this in advance, before it becomes a bigger problem.”
New York City is already at risk of flooding due to big storms that can cause the sea to penetrate inland or flood neighborhoods with torrential rains.
The resulting flooding can have destructive and deadly consequences, as demonstrated by Superstorm Sandy a decade ago and the still-potent remnants of Hurricane Ida two years ago.
“Scientifically, this is an important study,” said Andrew Kruczkiewicz, a principal investigator at Columbia University’s School of Climate, who was not involved in the research.
Their findings could help political officials draw up plans to combat, or at least prevent, rising tides.
“We cannot sit back and wait for a critical sea level rise threshold to be reached,” he said, “because waiting could mean missing out on take preventive measures and enlistment”.
New Yorkers like Tracy Miles may be skeptical at first.
“I think it’s a made-up story”, Miles said. He reflected again as he watched the sailboats bobbing in the water off midtown Manhattan. “We have an excessive amount of skyscrapers, apartment buildings, corporate offices and commercial spaces.”
New York is not the only place that is sinking. San Francisco also puts considerable pressure on the ground and active seismic faults in the region.
In Indonesia, the government is preparing a possible withdrawal from Jakarta, which is sinking into the Java Sea, to build a new capital on the higher ground of another island.
Bobby Caina Calvan is a journalist for the Associated Press
Translation: Elisa Carnelli