New York city sinking under its own buildings weight, study reveals

New York City is facing a pressing issue as a recent study reveals that the cumulative weight of its buildings is causing the city to sink. 

The implications of this gradual sinking process are particularly troubling for a city that is experiencing sea level rise at a rate more than twice the global average. By 2050, the sea level around New York City is projected to rise between 8 and 30 inches, exacerbating the challenges posed by the sinking phenomenon. 

Furthermore, scientists anticipate that the human-driven climate crisis will lead to more frequent and intense rainfall events, including nor'easters and hurricanes.

Tom Parsons, the lead study author and a research geophysicist at the US Geological Survey, commented, "We're a ways off from the ocean simply moving in... But we've had a couple of major hurricane events with Sandy and Ida in New York where heavy rainfall caused inundation in the city, and some of the effects of urbanisation have allowed water to come in." 

The study, published in the journal Earth's Future, aims to shed light on the potential future flood risks associated with high-rise buildings situated in coastal, riverfront, or lakefront areas. The researchers emphasise the importance of mitigating the hazardous impacts that may arise.

To determine the sinking rate, the study team calculated the combined mass of the 1,084,954 buildings across New York City's five boroughs, which amounted to approximately 1.68 trillion pounds (762 billion kilograms) — equivalent to the weight of roughly 1.9 million fully loaded Boeing 747-400s. 

Using simulations and satellite data, the researchers assessed the effects of this weight on the ground. They discovered an average sinking rate of 1 to 2 millimetres per year, with certain areas experiencing subsidence of up to 4.5 millimetres annually. The sinking, also known as subsidence, is influenced by various factors such as construction on soft soils, artificial fill, and post-glacial relaxation.

The study highlights that subsidence can pose a flooding threat even before the impacts of sea level rise become significant. This issue extends beyond New York City, with numerous coastal and inland cities grappling with subsidence problems worldwide. 

To address the risks associated with sinking cities, it is crucial to understand the effects of urban building loads on coastal land subsidence and identify vulnerable areas. As one of the most densely populated coastal areas in the world, New York City must comprehend the changing landscape, assess flood vulnerability, and make necessary preparations to mitigate future sea level rise.