New York City is sinking, but not because of the big buildings

New York City is sinking at a rate of half a foot per century.

new Stady Released last Wednesday, a NASA-led research team used high-resolution satellite images to analyze the ground elevation of about 300 square miles of New York City. This research was ostensibly follow-up A separate study was published In May, it was hypothesized that the city’s drop in ground elevation — known as subsidence — was due in part to heavy concrete buildings pressing down on the ground.

This conclusion was not entirely correct, Although it attracted a lot of headlines

The NASA team found that the city 1.68 trillion pounds Steel and stone had little effect on sinking, unless the structures were built on landfills, a fairly common practice in New York City. Subsidence hotspots spread throughout the five boroughs.

Coney Island in Brooklyn, Arverne-By-the-Sea in Queens, and the Rikers Island prison complex were also built on a landfill. The south side of Governors Island is basically a piece of landfill built on approx 5 million cubic metres From rocks and dirt resulting from subway excavations in the early 1900s. Just outside the metropolitan area, New Jersey’s two highways, Route 440 and Interstate 78, are drowning in areas built on infill.

The unsubmerged areas that the researchers found were sinking are due mainly to the melting of ice sheets that once covered the region about 20,000 years ago. During the last ice age, New York City lay outside a nearly mile-high ice sheet that covered most of New England. The weight of the ice pushes down onto the ground beneath it while forming bulges on the edges that lift the ground. These areas slowly sink again over time.

“Much like a mattress, if you push down, you get kind of a depression at the bottom of the mattress and then a bulge on the edge.” Robert Cobb, co-author of the study and co-director of Rutgers University’s Office of Climate Action. “Those [bulges] Come as you lift yourself up [off the mattress]”.

The main concern, the researchers said, is how submerged properties will exacerbate coastal flooding as sea levels rise simultaneously due to climate change. Knowing how much the Earth is sinking along with the rate at which sea levels are rising is important to prepare and design for the future, Cobb said.

Using satellites in space, the research team measured annual changes in land elevation from 2016 to 2023. They found that while the average sinking rate is less than a tenth of an inch per year, areas of built-up landfills are sinking about three times faster.

Hotspots like Arthur Ashe Tennis Stadium, which hosts the US Open, and LaGuardia Airport, which transports 14.5 million Passengers last year decreased by 0.15 and 0.18 inches, respectively.

“It’s entirely predictable that these places will sink a little faster because they’re not relying on solid structures,” he said. Brett Bozangalead author of the study and a NASA researcher.

For nearly two centuries, water levels around New York City have risen at an average rate 0.11 inch Annually, equivalent to the average growth of an adult’s nails over the course of one month.

Busanga said officials need to consider where land is sinking as they prepare for floods and climate change.

Not everything in the Big Apple is sinking, though. Some parts are on the rise, including the Newtown Creek, East Williamsburg and Woodside areas.

“We weren’t sure what to do with it,” Cobb said.

“We haven’t seen this in other studies,” Buzanga added.

Researchers suspect that these areas of high land are mostly due to human activities such as environmental remediation at Newtown Creek, a federally designated toxic Superfund site. These activities include groundwater pumping and injection wells to address water pollution, Cobb said. Underground construction of the city’s water system in Woodside may be another reason. The ground there was rising about 0.28 inches per year during the first four years of the study, then suddenly stopped.

“This tells you something about human activities, and we’re not sure what that is, but it could be useful for environmental monitoring,” Cope said.

Finding the reason why the Earth rises and falls will require deeper analysis and observation. NASA scientists plan to expand the project to include all of North America and eventually the entire planet.