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High-risk areas for global warming -

When it comes to global warming, certain areas of the world are at higher risk than others of suffering the consequences. Coastal cities, for example, are under an ever-increasing threat of flooding and storm surges.

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Hurricane Sandy -

In 2012, New York City suffered considerable damage when Hurricane Sandy flooded large parts of the city and caused widespread blackouts.

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Hurricane Ida -

Then, in 2021, more than a dozen New Yorkers lost their lives when they were unable to escape their basements that had been flooded by Hurricane Ida.

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Rising sea levels -

The city of New York is under an increased threat of flooding for two main reasons. Firstly, there is the ongoing problem of rising sea levels.

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Statistics -

According to The Guardian, the seawater that surrounds New York City has risen by around 9 inches (22 cm) since 1950.

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Predictions -

Moreover, it is predicted that major flooding events as the result of storms could be up to four times more frequent by the end of the 21st century.

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Varying degrees of risk -

As a result, the population of New York City, which is almost nine million, faces varying degrees of risk of flooding. Those who live within or directly adjacent to the floodplain face the greatest risk.

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Protective measures -

The city has already implemented some protective measures to try to mitigate this risk, such as building seawalls, raising roads, and creating artificial barriers.

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One size doesn't fit all -

However, these are one-size-fits-all solutions that are not necessarily fine-tuned to the specific requirements of New York City.

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National statistics -

Indeed, according to Forbes, by 2017 some 14% of the total US coastline had already been armored with seawalls, and that number is only set to rise.

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Subsidence -

The absence of a long-term solution to rising sea levels is compounded by the fact that relentless construction is also causing New York City to subside.

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Defining the term -

"Subsidence" is a general term used to describe the sinking of the Earth's surface. It can be the result of either natural processes or human activities.

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Important study -

In their open-access paper from May 2023, a group of researchers from the United States Geological Survey (USGS) and the University of Rhode Island (URI) looked at how the collective weight of New York's buildings is affecting its subsidence.

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The numbers -

Without going into detail on the calculations, they worked out that the more than one million buildings in New York City have a collective weight of 1.68 trillion pounds (7.64 x 10¹¹ kg).

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For context -

As per reports from CNN and The Guardian, that is the equivalent of roughly 1.9 million fully-fueled Boeing 747-400s, or 140 million elephants.

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Rate of subsidence -

As a result of this huge weight bearing down on the city, the authors of the paper concluded that NYC is sinking at an average rate of one to two millimeters (0.04-0.08 inches) per year.

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Complication -

It is important to note that this rate is an average; the actual rate at which different areas of the city are sinking depends on the material from which the ground they stand on is composed.

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Mix of materials -

There is a real mix of materials to be found in the ground of New York City. Some buildings in the city were built upon solid bedrock, such as schist.

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Exacerbated sinking effect -

Others, however, were built on softer materials, including mixtures of sand and clay, which greatly exacerbates the sinking effect.

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Some 4.5 millimeters per year -

According to the study, some areas of the city that are built on softer rock or artificial landfill are sinking as much as 4.5 millimeters (0.18 inches) per year.

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Dealing with the problem -

It is difficult to know what to do in the face of this double threat. Indeed, people are already talking about how long it will be before New York City is underwater.

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No evacuation -

However, the authors of the very enlightening paper do not call for an urgent evacuation of the city, or anything even half as drastic.

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Raising awareness -

Rather, they note that their aim with the paper is to raise awareness about how building new high-rises can contribute to the city's subsidence.

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Finding a long-term solution -

What does seem obvious is that cities will have to start planning for how to mitigate this risk in the long term, not least because repeated exposure to seawater can corrode steel and destabilize buildings.

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Other cities affected -

New York City is not alone in this struggle. One informative study from 2022 looked at subsidence rates in the 48 largest coastal cities in the world.

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Findings of the study -

Of those cities, 44 were found to have areas that are sinking faster than sea levels are rising. This statistic is particularly alarming when you consider that the 48 cities studied are home to one fifth of the global urban population.

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Drastic measures -

Rates of subsidence have already prompted some governments to take drastic measures. Indonesia, for example, is moving its capital from Jakarta to Nusantara.

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Nusantara -

Nusantara is a purpose-built city on the island of Borneo, which unfortunately comes with its own significant environmental challenges.

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Venice -

Another city often mentioned when talking about subsidence is Venice. Again, people are already talking about fears that it could become completely submerged.

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The New York case -

In the case of New York, inhabitants don't need to worry about the city being underwater next year. However, it is clear that subsidence is a real problem that the city with have to grapple with sooner rather than later.

Sources: (Forbes) (Phys.org) (The Guardian) (CNN)

See also: These cities may disappear by 2030 due to rising sea levels

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