New York City is sinking in part because of the extraordinary weight of its staggering buildings, exacerbating the flood threat to the metropolis from rising seas, new research has found.
The Big Apple may be the city that never sleeps, but it’s a city that’s definitely sinking, falling by about 1-2mm each year on average, with some areas of New York City plunging twice as fast, according to researchers.
This view exacerbates the impact of sea level rise, which is accelerating at about twice the global average as the world’s glaciers melt away and seawater expands due to global warming. The water flanking New York City has risen by about 9 inches, or 22 cm, since 1950, and major flooding from storms may be up to four times more frequent than now by the end of the century due to the combination of sea level rise and hurricanes strengthened by climate change.
“A deeply concentrated population of 8.4 million people faces varying degrees of danger from flooding in New York City,” researchers wrote in the new study, published in the journal Earth’s Future.
The authors added that the risks facing New York City will be shared by many other coastal cities around the world as the climate crisis deepens. “The combination of tectonic and anthropogenic subsidence, sea level rise, and increasing hurricane intensity implies an accelerating problem along coastal and river front areas,” they wrote.
This trend is reinforced by the bulk of New York City’s built infrastructure. The researchers have calculated that the city’s structures, which include the famous Empire State Building and the Chrysler Building, weigh a total of 1.68 tn lbs, roughly equivalent to the weight of 140 million elephants.
This enormous weight presses down on a jumble of different materials found in the grounds of New York City. While many of the largest buildings are located on solid bedrock, such as shale, there is a mixture of other sands and clays that have been built over, contributing to a sinking effect that nevertheless occurs naturally along much of the US East Coast. land is responding to the retreat of huge glaciers after the end of the last ice age.
“It’s not something to panic about right away, but there is this ongoing process that increases the risk of inundation from floods,” said Tom Parsons, a geophysicist with the US Geological Survey who led the new research.
“The softer the ground, the more compression there is from the buildings. It wasn’t a mistake to build such large buildings in New York, but we just have to remember that every time you build something there, you push a little bit more into the ground.”
In 2012, New York was hit by Hurricane Sandy, which flooded parts of the subway and caused extensive damage, including power outages. Then, in 2021, Hurricane Ida flooded areas of the city, causing several people to drown. Scientists say both events were exacerbated by the effects of global warming.
Parsons said New York and other coastal cities “need to plan for this. Repeated exposure to seawater can corrode steel and destabilize buildings, which you obviously don’t want. Flooding also kills people, which is probably the biggest concern.”
