We have passed the point of no return: sea level rise will soon directly affect hundreds of millions of people around the world. They will indirectly affect many more millions of people as transport links, water supplies and factories in low-lying areas have to be lost or relocated. What exactly is in store for us? The latest research suggests we are likely to see increase by one meter by the year 2100. If you consider how much carbon dioxide is already in the air and the oceans, up to three meters can be burned in over the next 200 years. And while that may seem a long way off, coastal water tables will rise much sooner, destroying infrastructure and causing toxic pollution, long before cities like Miami, New York and San Francisco are permanently flooded.
Where will all of these people, warehouses, water treatment plants, and railroads go as the interiors of large landmasses become drier? The forced migration of hundreds of millions of people will undoubtedly lead to serious international conflicts over space and basic resources like fresh water. Conflict is another word for war.
So can we adapt rather than migrate by learning to live with higher water? It’s an ironic question to ask in English, as the language arguably owes its origin to coastal flooding. Angels, Saxons and Jutes moved into Britain from a flat area of present-day Germany and Denmark during a period of extreme flooding from about 400 to 800 AD. Wealthy families fled to Britain from around the river once known as the Fifeldor, or ‘Gate of the Monsters’, an apt name for a river that is catastrophically flooded. When these elite families arrived, some historians believe up to a third of Britain’s population was enslaved. We can probably agree that migrating elites and enslaving indigenous peoples is not a model to emulate.
The Fifeldor is now called the Eider and is equipped with a massive storm surge barrier. Major coastal structures have been part of the flood response since the 1960s, including the Thames Barrier, the Rotterdam Barrier and the new concrete and steel floodgates in New Orleans designed by Dutch engineers. These gates are the most visible parts of complex machinery that coordinate pumps, tidal gates, and high water storage systems designed to control monster tides. But these systems will require more funding and focused political will to expand as rising tides and extreme storms become more common. Walls, gates and pumps are also inherently brittle in the sense that the consequences of their failure are catastrophic. It would be wiser to have systems that are ‘safe to fail’, as city planner Nina-Marie Lister has suggested, ie systems designed to fail gradually or at a rate that avoids damage. Otherwise, coastal defense machines could become the new sea monsters themselves.
Speaking of monsters, coastal regions are often contaminated, having housed military bases, landfills, chemical plants, or oil refineries. The ancient ones can be buried under various types of “caps”, but are usually not protected from flooding coming from below or from the side, such as groundwater and rainwater. Many of these industrial and military sites are already seeping into local groundwater. As sea and coastal water tables rise, these toxins can move in unexpected directions. If a volatile chemical like vinyl chloride comes in contact with a ruptured sewer line or simply gets into the gravel around a pipe, fumes can rise into homes, schools or workplaces, causing cancer and other diseases. When such pollutants enter shallow tidal waters, they kill fish, shellfish and birds. This is already happening in San Francisco Bay, where chemicals known as persistent organic pollutants have been buried on the shore, in a place where thousands of homes are now set to be built. Multiple tumors and reproductive abnormalities have been found in fish living in the adjacent mud.
So how could we live with all of this if, globally speaking, we simply have to? One possible strategy is to dig up the contaminated soil and render it inert by combining it with other chemicals, baking it, or filtering out the worst. We could also sequester them by binding the spooky materials into blocks of concrete, compacted earth, or glass. These excavations would leave us with extensive—and useful—ponds near areas where the sea and groundwater rise and rivers flood more frequently.
The Dutch pioneered the use of floating neighborhoods in ponds sheltered from waves and tides, with flexible infrastructure connections and “slip collars” on powerful pillars that hold them to shore while allowing them to rise and fall on small tides. Such a lake town could be built in some of the newly dug ponds, while others could be used for recreation or to support the shore animals. If we surround these ponds with low dikes, they could stay in place longer as seas continue to rise over the centuries, and be part of a “managed retreat” strategy.
Of course, most of the hundreds of millions who will be affected by sea-level rise live in less affluent countries, not in Europe or the US. To avoid having to move an unimaginable number of people when most have no viable destination, strategies for living with water must be cheap. Ideally, people in developing countries would be able to build and sustain their chosen strategy themselves – without hiring European or US companies or buying equipment they cannot afford to replace. If their strategy for higher water life is to move earth to create ponds and levees, local leaders who can direct manpower and equipment must be able to execute and maintain them independently. But since adapting in place prevents conflict and makes everyone safer, we all have an interest in making the world pay for it.
Floating cities bring many challenges: They need new water supply and sanitation infrastructures that are more localized and not as centralized. It is also true that they do not come close to the density of high-rise towers. And in some places they just won’t be appropriate or appropriate. But despite these problems, they provide a template for thinking about one of our civilization’s greatest problems. For the next 200 years, every person on this planet who values peace, health, and political stability must be mindful of the rising waters around us.
Kristina Hill is Associate Professor of Environmental Planning at the University of California, Berkeley.
The Water Will Come: Rising Seas, Sinking Cities, and Remaking the Civilized World by Jeff Goodell (Back Bay, £17.99)
All We Can Save: Truth, Courage and Solutions to the Climate Crisis edited by Ayana Johnson and Katharine Wilkinson (Oneworld, £13.99)
NYC 2140 by Kim Stanley Robinson (Orbit, £9.99)