Cities Around The World That Are Sinking

Human beings have always co-existed a little uneasily with nature, and perhaps no more so than in the modern age. The industrialization of the last century or so has brought with it a host of issues, none more pressing than global climate change. Unfettered burning of fossil fuels and the accompanying carbon dioxide emissions have resulted in a so-called "Greenhouse Effect" that slowly but surely warms the planet, causing ice caps to melt and sea levels to rise. Those rising sea levels are a serious problem in coastal regions, and the increasingly severe weather events caused by climate change are no joke, either — but since there's a ton of money to be made in fossil fuels, certain parties are a touch resistant to altering the status quo. Despite scientists telling anyone who will listen that green energy could literally save the planet, CO2 emissions reached their highest level ever in 2021.

About those coastal regions — when combined with the wanton extraction of groundwater, which over time causes the ground to settle (an effect referred to as ground subsidence), increased flooding brought on by climate change can contribute to a bit of a sinking feeling among residents of those regions. That is to say, there are many large urban population centers around the world that are literally sinking — and if drastic measures are not taken over the next few decades to alleviate the problem, some of them could disappear altogether under the ocean.

The city of Venice, Italy has famously been half-underwater for the entirety of its existence; that's part of its charm, as it's a lot tougher to row gondolas through dusty ditches than scenic canals. One would think that it would be more prepared than most areas to handle rising levels of water — but at the time of the city's founding roughly 16 centuries ago, those levels were about six feet lower than they are today, and there is only so much that can be done to accommodate such drastic change.

The 2022 study examining subsidence in coastal cities concluded that Venice is taking a long bath, and not the pleasant, relaxing kind. It is sinking at a rate of 1 to 2 millimeters per year, and the islands in its famed lagoon — over a hundred of them — are subsiding even faster. The city is also among those in danger of disappearing altogether, but Venice is not without a plan. Begun in 1992, Mose — a system of mobile barriers designed to protect the city from sea surges — is scheduled to finally be completed in late 2023. This, however, does nothing to combat the complicated issue of ground subsidence in Venice — and some, like nonprofit We Are Here Venice executive director Jane da Mosto, have deemed it "a highly impacting, heavily engineered and ... overly complicated solution" (via BBC).

In 2022, a study was published in the journal Nature succinctly titled "Sinking Cities, Rising Seas." The study concluded that the highest concentration of countries with out-of-control land subsidence rates was in Southeast Asia, with the highest rates of subsidence to be found in that region exceeding an eye-watering 16 millimeters per year. This is extremely bad news for very large, still-expanding cities such as Ho Chi Minh City — the Vietnamese capital, home to over 9 million people, which in recent years has been experiencing flooding like never before in its history.

As reported by Channel News Asia, government projects to raise roads and structures have been undertaken to combat the encroaching waters — but this Band-Aid approach offers nothing in the way of long-term solutions, and with the city's population (and therefore, new construction) continuing to proliferate, the Ho Chi Minh could be headed for disaster unless more pragmatic strategies are employed. Nguyen Viet Ky, who leads the Geotechnics Division at Ho Chi Minh City University of Technology, singles out all the new development as being particularly problematic, saying, "It's clear that there's too much development density concentrated in weak foundation areas." If it continues on its current course, the aforementioned study suggests that Ho Chi Minh City, too, could soon face an existential threat from the rising waters.

The Netherlands faces a land subsidence issue that is worse than most. Its famous windmills are not just for tourists to take selfies in front of; for hundreds of years, they've been used to pump water out of the ground for use in farming, and some areas of the country are sinking at the ridiculous rate of 8 millimeters annually. The Dutch, though, take a radically different approach to keeping themselves dry. Rather than trying to hold back the waters or raise structures above it, they seek to live with it — by giving the inevitable floods friendly places to go, where they will cause the least damage and hardship.

Speaking with The New York Times, water management expert Henk Ovink described how more traditional approaches don't make sense for cities like the slowly sinking Rotterdam, of which 90% is below sea level. "We can't just keep building higher levees ... We need to give the rivers more places to flow," he said. This includes making use of public spaces, like parks and plazas, to double as overflow areas in the event of flooding. The approach seems to be working — a recent study titled "City-To-City Learning for Urban Resilience: The Case of Water Squares in Rotterdam and Mexico City" concluded that the use of overflow areas has greatly contributed to Rotterdam having one of the more effective flood management strategies worldwide, one worthy of emulation.

With a population of over 15 million, Kolkata, India (formerly Calcutta) is another region in which a whole lot of people are threatened with displacement due to extreme flooding. Even worse, the risk to the region may have actually been underestimated in recent years, as spelled out in a study conducted by scientists at the National Center for Atmospheric Research in Boulder, Colorado, titled "Increased Exposure of Coastal Cities to Sea Level Rise Due to Internal Climate Variability." Those last three words are key: The paper suggests that current models forecasting rising sea levels fail to take into account natural fluctuations in climate, which could spell... well, an even greater disaster for low-lying areas like Kolkata.

In an interview with India Times, the study's co-author Aixie Hu sounded the alarm, saying, "In a worst-case scenario, the combined effect of climate change and internal climate variability could result in local sea levels rising by more than 50% of what is due to climate change alone." That is, obviously, incredibly significant. Compounding the issue, Kolkata's sewer network is roughly a century old and only covers about half of the city's total area. These factors, combined with an estimated subsidence rate of around 13 millimeters annually and continued development eating away at Kolkata's natural flood defenses, could spell catastrophe for the city in the near future — and currently, very little is being done to address the issue.

Florida is, obviously, surrounded by water, and the coastal city of Miami is another that is under threat from multiple angles. A 2020 study entitled "Local Land Subsidence in Miami Beach and Norfolk and its Contribution to Flooding Hazard in Coastal Communities" predictably found what its title promised: Miami is sinking at an annual rate of about 2 millimeters annually, and the study's author Shimon Wdowinski told FUI News that since the Western portion of the island offshoot of Miami Beach was built on reclaimed wetlands, it is sinking even faster.

Unfortunately, the city's government seems to have its head in the sand (figuratively, of course) with respect to the issue, because the construction of high rises and other high-end real estate development in the threatened areas has not slowed in recent years. These are the very areas that, according to University of Miami climate scientist Dr. Harold Wanless, could be literally underwater in just a few decades if climate change has its way. "Now since the ice melt started we're [seeing rising sea levels] of almost two feet per century," he told CBS News. This has contributed to higher and more frequent high tides — and if Miami's slow descent continues along with those rising water levels, Dr. Wanless' prediction is dire. "The tide is coming in," he said, "and eventually it's not going to go back out."

Like many coastal cities, the Big Apple faces plenty of threats from land subsidence and rising waters. But the city's slow sinking, at an average rate of 1 to 2 millimeters per year, is being accelerated by one unique factor: the sheer weight of all of its many massive structures. A 2023 study titled "The Weight of New York City: Possible Contributions to Subsidence From Anthropogenic Sources" singled out New York's famed skyscrapers as a partial culprit in its steady descent. The study's lead author, U.S. Geological Survey geophysicist Tom Parsons, pointed out to Live Science that although the rate of subsidence is relatively slow, rising water levels — at roughly the same rate — will eventually combine with the subsidence to "pose inundation challenges in New York."

According to The New York Times, among several possible solutions proposed by the U.S. Army Corps of Engineers, one has emerged as a front runner: a six-mile long sea wall, located a mile outside of Manhattan in New York Harbor, which would cost a staggering $119 billion. The proposal has, somewhat predictably, divided New Yorkers. While the Times reported that the barrier has strong support among some communities, some knowledgable voices — like that of Paul Gallay, head of the environmental group Riverkeeper — have been raised in dissent. "Barriers are a shiny object, a silver-bullet fix luring us away from where need to go," Gallay said. "The danger of one big wall is that if it fails, we're all in danger. We need layered solutions."