New York City may be sinking under its own weight because the buildings are too heavy, scientists warn

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Scientists estimate the mass of the 1,084,954 buildings within the five boroughs of New York City is 1.68 trillion pounds.

An aerial view of the New York City skyline from the south.
New York City is slowly sinking under its own weight. (Image credit: Alexander Spatari via Getty Images)

The combined weight of New York City's buildings may be causing the metropolis to sink, researchers have said. However, there may be other reasons why the city is sinking — including the way the earth continues to shift after the end of the last ice age more than 10,000 years ago, scientists added.

Understanding how and why areas such as New York City may be sinking helps researchers estimate the flood risks these areas may face in the future because of climate change. Sea levels along the Atlantic Coast of North America are expected to rise three to four times faster than the global average, researchers noted.

"Sea level rise is eventually going to pose inundation challenges in New York and globally," study lead author Tom Parsons, a geophysicist at the U.S. Geological Survey, told Live Science.

GPS data suggest lower Manhattan is sinking, or subsiding, at the rate of about 0.08 inch (2.1 millimeters) per year. 

In addition to this natural cause of subsidence, Parsons and his colleagues wanted to explore the potential effects of artificial causes, such as buildings. He came up with the idea while visiting his wife's family in Belgium in 2019.

"We happened to be staying next to the cathedral in Antwerp," Parsons said. "I kept looking at the huge foundation stones and thinking about how they all had to have been brought from many miles away, and then piled up in one concentrated spot, like building a small mountain. I got curious about what that might be doing to the earth below it."

All buildings will sink into the ground or "settle" a little after they are built, "even those built on hard rock," Parsons said. "Those on softer soils will settle more."

The scientists estimated that the mass of the 1,084,954 buildings within New York City’s five boroughs equaled 1.68 trillion pounds (762 billion kilograms) distributed over a 300-square-mile (778 square kilometers) area.

Still, the scientists also found some parts of the city displayed much faster subsidence rates. They noted this may be due to the weight of buildings, although they cautioned there might be other possible causes.

Parsons noted that New York City is on average only sinking a tiny amount per year. "However, sea level rise at New York is about 1 to 2 millimeters per year, so every millimeter of subsidence is equivalent to moving a year ahead in time with regard to rising ocean levels," he said.

The scientists published their findings May 8 in the journal Earth's Future.

Charles Q. Choi
Charles Q. Choi
Live Science Contributor
Charles Q. Choi is a contributing writer for Live Science and Space.com. He covers all things human origins and astronomy as well as physics, animals and general science topics. Charles has a Master of Arts degree from the University of Missouri-Columbia, School of Journalism and a Bachelor of Arts degree from the University of South Florida. Charles has visited every continent on Earth, drinking rancid yak butter tea in Lhasa, snorkeling with sea lions in the Galapagos and even climbing an iceberg in Antarctica.