Scholars Advocate “Managed Retreat”—Before Climate Change Sinks Coastlines

The question is no longer if, but when and how. 

A traffic sign with the words "Stop Road Closed" submerged in several feet of water
Photograph by tornadochaser/iStock

As the climate changes and seas rise on coastal communities around the world, the best option for some will be to flee. The idea of having to move people and communities away from the coastline is usually thought of as a far-off, worst-case event—a last resort after all else fails. But in a Science paper published today, researchers argue that the relocation of coastal communities is no longer a question of if, but when and how. Rather than seeing it as a failure to adapt, they write, strategic withdrawal—a process called “managed retreat,” the carefully planned removal of residents and assets, and in some cases whole communities, from harm’s way—should be regarded as a viable option alongside ideas such as seawalls or other mitigations. “Retreat is happening,” says lead author A.R. Siders ’07, J.D.’10, who spent this past year as a fellow at Harvard’s Center for the Environment. But so far, relocations have been mostly ad hoc and individual. “For retreat to work well,” Siders says, “it needs to be part of a larger strategy, tailored to local circumstances, to long-term community goals. And it needs to be about equity, about making sure everyone is better off afterward.” 

Siders first began thinking seriously about managed retreat in 2012. That October, she was working as a postdoctoral researcher at Columbia’s Center for Climate Change Law, when Hurricane Sandy hit New York and New Jersey, causing record-breaking storm surges, floods, and destruction. Afterward, she says, she noticed something missing from the recovery discussions. “There was all this conversation about, how do we build back. And no one was having the conversation of, should we build back? Or, where should we build back.” Half the new housing units that New York City officials had proposed at the time, she says, were in Sandy’s floodplain. 

The risk from rising seas is enormous. In the United States, coastline communities account for nearly 40 percent of the population—more than 123 million Americans. Globally, three-fourths of the world’s cities are located along shorelines, home to many hundreds of millions. Siders and her co-authors are frank about the complexities involved in the changes they propose. They stress the need to reckon with numerous factors: coordinating moves across jurisdictions, or across international lines; cultural and social considerations, like the wish to remain near burial grounds or ancestral lands; reparations for losses or damage to historic practices; long-term social and psychological consequences; financial incentives that often contradict environmental imperatives; and the critical importance of managing retreat in a way that protects vulnerable and poor populations and that doesn’t exacerbate past injustices.  

“It’s a lot to think about,” Siders says. “And there are going to be hard choices. It will hurt—I mean, we have to get from here to some new future state, and that transition is going to be hard.…But the longer we put off making these decisions, the worse it will get, and the harder the decisions will become. Already, people are getting hurt. That’s happening now. People are losing their homes. They’re having to abandon their property and take that financial loss without support; their loved ones are dying in disasters.” And meanwhile, she adds, new construction continues in areas from which people will almost certainly have to retreat in the future. “There is real, significant damage in not having these conversations.” 

One problem is a lack of research to draw from. “Though there has been some experience with retreat in the world to date,” says co-author Katharine Mach ‘04, “unambiguously, we’re at square one, in terms of understanding strategy…and understanding how we innovate tools for management and deployment.” The paper lists examples of a few of those experiences from around the globe: bans on rebuilding, government buybacks of property and homes or acquisitions of at-risk land, required resettlements, and a few instances of whole-community relocations. But follow-up research has been limited, and data and recommendations are scarce. There are few records, the paper notes, of where people relocate after a retreat program, and even fewer records of how they have fared. There is little data to assess public perceptions of fairness and legitimacy. 

The authors call for comprehensive evaluations and longitudinal studies, and a “spirit of experimentation” in future retreats: “a willingness to try new things paired with rigorous research.” Co-author Miyuki Hino says that the lack of research was a serious handicap when she worked as a climate-change adaptation consultant several years ago. “I was really seeing these organizations—whether it was an international development organization or a transportation authority—grappling with really hard choices. They wanted to make sure their investments would be resilient to a changing climate; they don’t want to spend a lot of money building infrastructure that will be underwater in 20 years. And they need evidence to make decisions on.” When it came to some topics, like managed retreat, Hino found that the evidence just wasn’t there.    

Retreat won’t be the answer for every coastline, Siders says, just as rising ocean levels aren’t the only climate-related hazard forcing people to relocate: there are wildfires, droughts, flooding from lakes and rivers. In recent years, strong storms have battered her own hometown of Duluth, Minnesota, and the city has begun considering whether to move back from the shore of Lake Superior, to give the water more room. In all these discussions of managed retreat, she says, “imagination is really key.” Accepting withdrawal as a potential necessity “opens up space to start imagining all the ways it might be possible to execute, instead of focusing on all the ways it’s difficult.”  

Siders and her co-authors stress something else about the idea of retreat: that it represents not only loss, but opportunity. “People always talk about retreat as loss and failure. Like, ‘We’ve lost that battle.’…But there is an opportunity here to thrive too, to start over in some ways. The best conversation we can have about retreat is to ask, at a community level, ‘What do you want your community to look like in 50 years? In 70 years?’…That, to me, is the real lesson of climate change—none of these places will look the way they did when your grandparents were there. The question is, what do we want them to look like for our grandchildren?” 

That future is not as far away as we imagine. Headlines in recent years about climate refugees fleeing troubled areas by the millions—and the projections that as many as a billion people eventually may be displaced by sea-level rise and floods—serve as a warning, Siders says. “That’s what happens if there’s no managed retreat.”  

“The good news,” she says, “is we have a chance to do something better. We can see disaster looming, and we can do something about it. We can choose something more strategic, more effective, more fair.”

Read more articles by Lydialyle Gibson

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