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Sea level rise is unstoppable. Cities can adapt, but they need to think bigger

Sea level rise will erase entire cities and render homes, buildings, and roads unusable. A new book lays out key design strategies to help us adapt.

Sea level rise is unstoppable. Cities can adapt, but they need to think bigger
[Photos: Eirik Soldal/Unsplash, Nirzar Pangarkar/Unsplash]
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The climate and the oceans have warmed beyond the point of no return. According to a new book from oceanographer John Englander, there is nothing we can do to stop the melting of the Greenland and Antarctic ice sheets. Rising sea levels are now inevitable. By the end of this century, sea levels could be 10 feet higher than they are today.

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The societal impacts of sea level rise will be immense. The shoreline as we know it will be completely reshaped, inundating parts of 10,000 coastal communities around the globe and rendering millions of homes, buildings, roads, and other infrastructure worthless or unusable. Some coastal cities could see flooding every day by mid century, less than 30 years from now. Low-lying cities like Miami, New Orleans, Copenhagen, and Shanghai could be virtually erased.

“It’s pretty bad,” Englander says. “But it’s also a design challenge.”

[Photo: courtesy of Moving to Higher Ground]
Englander’s book, Moving to Higher Ground: Rising Sea Level and the Path Forward, makes the case that we need to start planning and designing for this massive disruption today. The book is oriented toward those most directly able to help the world’s coastal communities redesign themselves: engineers, urban planners, architects, and policymakers, plus the financiers and insurance companies that often determine what actually gets developed.

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“Once you understand that we could have meters of rise in a century, you realize we can’t wait for the water to arrive. You need to change infrastructure, where your ports and airports are, and how coastal development happens,” Englander says. “At the moment we’re thinking small. We’re putting in pumps and raising streets 50 centimeters at a time. We need to think bigger.”

Building on his previous book, High Tide on Main Street, Englander offers a series of strategies for beginning the process of rethinking coastal and flood-prone communities for a near future with much higher seas.

Accept the inevitability of sea level rise

The sea level is already rising, and will rise much faster in the decades to come, Englander says. “Sea level in the last century has risen about 20 centimeters. And that’s happened gradually enough that we didn’t really notice it. But it’s accelerating. In fact, it’s been almost doubling every decade for the past 30 years. So we’re just in a new reality,” he says.

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The rising temperature of the oceans means that melting will continue to increase. “The planet’s already warmed one degree celsius. We’re talking about whether we can keep the warming to another degree celsius, and most people are starting to doubt that’s possible,” Englander says. “But even if we could keep it to the Paris climate accord goal through all sorts of renewable energy and efforts to reduce greenhouse gases, which would be great, we’re still going to have more sea level rise. The fact that sea level rise is unstoppable is the first thing we have to really look at squarely.”

Move inland and rethink the coast

Several feet of sea level rise will put parts of many cities under water. Recognizing this and mapping the areas most likely to be affected will help governments and planners understand if and how existing development will need to adapt. For some places, that may mean raising structures. For others, it may mean abandoning entire parts of town and redeveloping on higher elevations—relocations that can be difficult prospects, especially for what may already be marginalized communities.

“We have to move some things further inland, we have to move somethings higher, put some things on floats. We’ll have to become very inventive,” Englander says. “The good news is we have decades to begin adapting. But it means a fundamental rethinking of our infrastructure.”

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And that means more than just roads and electrical lines. In many cities, coastal infrastructure is vital to regional civil operations and national economies. “We’re not going to abandon the coast. You can’t give up the coast for ports and fisheries and hydropower and cooling of industrial plants, for all sorts of reasons,” Englander says. Redesigning and rethinking these coastal infrastructures will be essential.

Plan for the next century’s rise

Englander says governments, urban planners, and developers need to be thinking not just about the sea level increase in the next 20 or 30 years, but what could come in the next century. There’s a functional lifespan of about 100 years for major infrastructure projects like subway tunnels and bridges.

The same long lifespans apply to cities themselves, and planners are beginning to take sea level rise into consideration when outlining long-term plans. Boston’s Coastal Flood Resilience Design Guidelines plan for around a 1% chance of flood risk in the year 2070, on top of 40 inches, or 1 meter, of sea level rise. Other city efforts plan around 5 feet of sea level rise. “That’s probably the most ambitious plan in the United States right now,” he says. The design guidelines include ideas for making smooth transitions a few feet up from the street level to the raised lowest levels of buildings, and using waterfront parks and vegetated berms for flood control. “They’re even looking at in this century some streets could become canals. That’s pretty bold thinking.”

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He also points to the example of low-lying Singapore, where the government is requiring that the construction of a new airport terminal be at least 5 meters above sea level.

Design for adaptation

Adaptation efforts and rebuilding don’t have to happen all at once. Englander suggests engineers and builders think about the concept of adaptive engineering, or designing a project today so that it can be easily amended or adapted many years in the future.

Take a new bridge, for example. Given the sea level rise in the coming decades, that bridge would likely be designed to accommodate at least three feet of potential rise. “If you contemplated that you need to raise it three meters at some point in the future, you might build the foundation so that it can support a higher structure,” Englander says.

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“I suggest planning for the first meter as soon as possible,” he adds, noting that the cost of raising a building three feet is much less than raising it 10. “We don’t know exactly when mid-century that’s going to happen. But most places can design for a meter of sea level rise.” If designed for later adaptation, those projects could be adjusted when the pace and scale of sea level rise demands it. Because whether we’re ready for it or not, the sea level is going to significantly alter what we now know as the coast.

“There are a lot of things you know, like technology or politics, that might change. This isn’t going away,” he says. “There is no other option to melting the ice and raising the sea level by meters. So this will be the story of the century.”