New York is sinking under its own weight. The huge skyscrapers the city is known for are too heavy for the underground. That’s according to a new study that looks at how the Big Apple looks like below.
Soil subsidence is not a strange phenomenon in itself. This can happen through the extraction of minerals, but also through the drying out of peat soil, for example. There are many causes, but the weight of cities themselves has never been considered.
Now it appears that it does have an effect: New York is sinking by 1 to 2 millimeters per year due to the weight of the skyscrapers. Those few millimeters may sound harmless, but in some parts of the city it goes much faster. That could become a major problem for the already low-lying city with more than 8 million inhabitants.
Bit of awareness
The study should therefore encourage policymakers to take measures to reduce the risk of flooding. The goal of the study is to raise awareness that any tall building built along a coast, river or lake may contribute to future flood risk. University of Rhode Island.
It also makes clear what man brings about with all his structures. Scientists estimate that everything humans have ever made weighs more than anything living on Earth. Buildings and roads are heavier than all trees, shrubs and plants put together. All the plastic weighs twice as much as the weight of all animals combined.
New York weight
In this new study, the researchers calculated the total weight of New York’s more than 1 million buildings. That amounts to a staggering 764 billion kilograms. To be able to say something about the pressure that all those kilos cause on the earth, the city is divided into squares of 100 by 100 meters and then the mass is converted into downward pressure by calculating the effect of gravity.
Only the weight of the buildings was considered, not that of roads, bridges and other pavement. Despite this limitation, the researchers arrived at a better calculation of the subsidence than previous studies, because they did include the complex subsurface of the city, which consists of sand, silt and clay deposits, but also rock. And that provides interesting information: especially clay soil and artificially filled soil are vulnerable to subsidence. More elastic subsoil springs back after construction, while rock does not collapse as hard.
Not the only one
Increased urbanization, including drainage and groundwater pumping, will only add to the subsidence problem, the researchers warn. Moreover, New York is by no means the only city affected by this. A quarter of Jakarta may be under water by 2050. Parts of the Indonesian capital are sinking at almost 11 centimeters per year because groundwater is pumped up. The authorities of the city with a population of 30 million are taking into account that they will have to move if climate action is not taken quickly.
But New York is also at a huge risk of flooding. Large parts of Manhattan are only 1 to 2 meters above sea level. Previous hurricanes have already made it clear how quickly the largely paved city can flood. “New York is exemplary of a growing number of coastal cities around the world that are experiencing subsidence. So there is a shared global challenge to limit the increasing risk of flooding,” he concludes.
Worse than sea level rise
A 2022 study of the situation in 99 coastal cities showed that subsidence is a bigger – or at least underestimated – problem compared to sea level rise, when it comes to the risk of flooding. In most cities, the subsurface is subsiding faster than sea levels are rising, which means residents will experience flooding faster than currently predicted in climate models.
The Netherlands is also struggling with subsidence. Our largest urban area, the Randstad, is also below sea level. The north and west of our country in particular suffer from subsidence. In some places, the soil subsides by half an inch a year. Low water levels are usually the cause. Peat soils in particular are subsiding as a result. Damage to foundations, among other things, will run into the tens of billions until 2050, experts estimate. Soil subsidence also contributes to CO2 emissions. All the more reason to do our best to combat climate change.