As rising oceans threaten NYC, study documents another risk: The city is sinking

Channel 3000 News/AP ^ | May 31, 2023 | AP Staff

[Diana in Wisconsin]

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 recently 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 of concrete, metal and glass — about the mass of 4,700 Empire State buildings — pressing down on the Earth.

The rate of compression varies throughout the city. 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. At some point, those two levels will meet," said Parsons, whose job is to forecast hazardous events from earthquakes and tsunamis to incremental shifts of the ground below us.

But no need to invest in life preservers just yet, Parsons assured.

[woodbutcher1963]

Manhattan is a very interesting study in geology. Lower Manhattan is all rock. Therefore, the large buildings especially down by Wall Street.

Then going north there is very little of any height until you get up to the Empire State building on 23rd street. Then a whole bunch up through Mid Town and on each side of Central Park.

Greenwich Village is all land filled swamp.

[Gay State Conservative]

I'll believe the oceans are rising when Osama Obama,algore and Zuckerberg sell their beachfront mansions and move to Colorado.

[Gay State Conservative]

I've read that midtown and the southern tip are the only parts with bedrock that's sturdy enough to handle skyscrapers.

[woodbutcher1963]

That is my understanding too. If you look at the old maps of Manhattan, from the 1700s there was a wet area where Greenwich Village is now. That is why all the buildings are only 4 stories tall.

Unlike the Back Bay section of Boston where there was rock underneath that water in the Charles River. Which is why the John Hancock tower and the Prudential building are there.

I remember walking from the USS Intrepid on the West Hudson River back up to the Hotel Penn on the south side of Macy’s between 6th & 7th avenue. It is surprisingly UP hill in elevation to the middle of the island.

[SamAdams76]

I believe you are referring to the old Collect Pond. The below is a rendering of what it might have looked like during the Colonial era. Hard to believe Manhattan used to be so pastoral.

[woodbutcher1963]

Yes, and the reason it is called Wall Street is because in the mid 1600s the Dutch Settlers built a 12’ high WALL. It ran east to west (where Wall street runs today) to keep the Indians out.

[JimRed]

That natural process happens everywhere as ground is compressed, but the study published recently in the journal Earth's Future sought to estimate how the massive weight of the city itself is hurrying things along.

It is probably still rebounding from the hundreds of feet of ice that covered it until 12-15,000 years ago.