Recent research has revealed that the city of New York is experiencing sinking due, in part, to the immense weight of its towering buildings. This subsidence exacerbates the risk of flooding faced by the city as sea levels continue to rise.
New York, a city which has one of the most famous skylines in the world, is considered a concrete jungle with 762 million tonnes of buildings. Skyscrapers, the pride of the Big Apple, which were built to accommodate the rising demand for workplaces, might just be what sinks the city.
Why is New York Sinking?
Researchers at the United States Geological Survey and the University of Rhode Island have stated that the city is sinking with a rate of 1-2 millimeters per year. It has also been reported that some areas of the city are sinking at double this rate.
While midtown Manhattan is constructed directly on solid bedrock, the lower Manhattan and southern Brooklyn areas predominantly rely on artificial fill, comprising a combination of materials. This composition renders them more susceptible to subsidence when subjected to the weight and pressure exerted by buildings.
This sinking of New York City is also due to the effects of the accelerated sea level rise, which is currently rising at approximately twice the global average. This rise is attributed to the melting of glaciers and the expansion of seawater caused by global warming.
The impact of sinking in New York City is amplified by its extensive built infrastructure. The research team determined that the combined weight of the city’s structures, including iconic landmarks like the Empire State Building and Chrysler Building, amounts to a staggering 1.68 trillion pounds. To put this into perspective, it is roughly equivalent to the weight of 140 million elephants.
This substantial mass exerts pressure on the diverse array of materials found beneath the city’s surface. While some of the tallest buildings rest on solid bedrock, such as schist, there is a mixture of sands and clays that have accumulated over time, contributing to the sinking phenomenon.
This sinking effect is not unique to New York City but is a natural occurrence observed along much of the eastern coast of the United States as the land adjusts in response to the retreat of enormous glaciers following the conclusion of the last ice age.
The lead geophysicist for this research at the US Geological Survey, Tom Parsons stated that the degree of compression from the buildings increases with the softness of the soil. He said that constructing large buildings in New York City was not an error, but it is crucial to consider that each new construction contributes to further ground subsidence.
How this is affecting the city
Over the years, the water surrounding New York City has risen by approximately 9 inches or 22 centimeters since 1950. The combination of sea level rise and hurricanes intensified by climate change is projected to increase the frequency of major flooding events from storms by up to four times the current rate until the culmination of the century.
In 2012, New York City experienced the devastating impact of Hurricane Sandy, resulting in subway flooding, extensive damage, and widespread power outages. Similarly, in 2021, Hurricane Ida caused flooding in various parts of the city, tragically leading to several drownings.
Scientists assert that the severity of both events was intensified by the consequences of global warming. The researchers stated that flooding results in the buildings being repeatedly exposed to sea water which the steel and destabilizes them. An increase in floods means an increase in the threat to people’s lives.
Other places that are sinking
In a study conducted in 2022, researchers examined 48 of the world’s largest coastal cities, which collectively house approximately one-fifth of the global urban population. The findings revealed that in 44 of these cities, certain areas were sinking at a faster rate compared to the rise in sea levels.
Concerns are mounting that Venice could eventually face complete submersion due to subsidence and rising sea levels.
In Jakarta, the city is sinking rapidly, largely because of excessive groundwater extraction. The sinking of Jakarta into the Java Sea has even prompted Indonesia to make the decision to relocate its capital to Nusantara.
San Francisco, like these cities, is exerting pressure on the ground, including the active earthquake faults present in the region.