NEW YORK — If rising oceans aren’t worry enough, add this to the risks New York City faces: The metropolis is slowly sinking under the weight of its skyscrapers, homes, asphalt and humanity itself.
New research estimates the city’s landmass is sinking at an average rate of 1 to 2 millimeters per year, something referred to as “subsidence.”
That natural process happens everywhere as ground is compressed, but the study published this month in the journal Earth’s Future sought to estimate how the massive weight of the city itself is hurrying things along.
More than 1 million buildings are spread across the city’s five boroughs. The research team calculated that all those structures add up to about 1. 7 trillion tons (1. 5 trillion metric tons) of concrete, metal and glass — about the mass of 4,700 Empire State buildings — pressing down on the Earth.
The city’s rate of compression is different. Midtown Manhattan’s skyscrapers are largely built on rock, which compresses very little, while some parts of Brooklyn, Queens and downtown Manhattan are on looser soil and sinking faster, the study revealed.
While the process is slow, lead researcher Tom Parsons of the U.S. Geological Survey said parts of the city will eventually be under water.
“It’s inevitable. The ground is going down, and the water’s coming up. Parsons’ job involves forecasting hazardous events, from tsunamis and earthquakes, to small shifts in the earth below.
But no need to invest in life preservers just yet, Parsons assured.
The study only notes that buildings are contributing to the changing landscape in a small way, Parsons said. Parsons and his team of researchers reached their conclusions using satellite imaging, data modeling and a lot of mathematical assumptions.
It’ll take hundreds of year — the exact date is not known — for New York to become America’s Venice. Venice is famously sinking in the Adriatic Sea.
But parts of the city are more at risk.
“There’s a lot of weight there, a lot of people there,” Parsons said, referring specifically to Manhattan. “The average elevation in the southern part of the island is only 1 or 2 meters (3. 2 or 6. 5 feet) above sea level — it is very close to the waterline, and so it is a deep concern.”
Because the ocean is rising at a similar rate as the land is sinking, the Earth’s changing climate could accelerate the timeline for parts of the city to disappear under water.
“This does not mean we should stop building. This doesn’t necessarily mean the buildings themselves are the only cause. Parsons explained that there are many factors. “The purpose was to point this out in advance before it becomes a bigger problem.”
Already, New York City is at risk of flooding because of massive storms that can cause the ocean to swell inland or inundate neighborhoods with torrential rain.
The resulting flooding could have destructive and deadly consequences, as demonstrated by Superstorm Sandy a decade ago and the still-potent remnants of Hurricane Ida two years ago.
“This study is important from a scientific standpoint, said Andrew Kruczkiewicz a senior research scientist at Columbia University’s Climate School who wasn’t involved with the research.
The findings of the study could be used to inform future plans by policymakers in order to prevent or combat rising tides.
“We can’t sit around and wait for a critical threshold of sea level rise to occur,” he said, “because waiting could mean we would be missing out on taking anticipatory action and preparedness measures.”
New Yorkers such as Tracy Miles can be incredulous at first.
“I don’t believe it. Miles replied. He thought again while looking at sailboats bobbing in the water edging downtown Manhattan. “We do have an excessive amount of skyscrapers, apartment buildings, corporate offices and retail spaces.”
New York City isn’t the only place sinking. San Francisco is also putting pressure on the earth and active faults in the area. Indonesia is planning to move from Jakarta which is sinking in the Java Sea and build a new capital on a higher island.
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