Weight of New York’s buildings is causing the city to sink, study says

The weight of New York City’s buildings is causing the metropolis to sink, increasing the risk of flooding, a new study said.

The city is descending at an average rate of 1-2 millimeters (0.1-0.2 centimeters) per year, according to research published this month in the peer-reviewed science journal Earth’s Future. Some areas are sinking far faster than the average.

The phenomenon, known as subsidence, puts New York City at a greater risk of floods, a danger exacerbated by rising sea levels and more intense storms.

“A deeply concentrated population of 8.4 million people faces varying degrees of hazard from inundation in New York City,” the study warned.

New York City’s buildings were estimated to weigh a cumulative 1.68 trillion pounds. There are slightly more than 1 million buildings in the five boroughs, with the average structure weighing 1.55 million pounds.

The researchers only calculated the weight of buildings and their contents, and did not include urban features such as roads, bridges and subways, meaning the actual weight of the city is likely heavier than the estimate.

The city’s skyscrapers exert the most downward pressure, but most are built on bedrock, while other structures are located on top of softer sand and clay.

New York City is built on the water, with the densely-packed central borough of Manhattan located on a narrow island.

Other cities around the world are also sinking due to denser construction patterns and face similar risks, the study’s authors said, warning of “an accelerating problem along coastal and riverfront areas.”

Natural processes, such as the effects of the tectonic plates, also contribute to the elevation change.

The scientists came to their findings by calculating the weight of the city’s buildings, modeling the downward pressure they exert, and measuring elevation change using satellite data.

In 2012, Hurricane Sandy swamped parts of New York City and caused power blackouts and lasting damage to infrastructure.

Hurricane Ida in 2021 caused massive flooding, leaving several people dead.

North America’s Atlantic Coast faces a threat of sea level rise 3-4 times higher than the global average, the study said.