The case for ‘managed retreat’ in the face of climate change


It needn’t be as drastic as it sounds, as Richard A Lovett reports. 


Flooding in the coastal city of Cebu, Philippines.

J Lloa

As climate change mounts and communities come under increasing pressure from fires, floods, heat and sea level rise, people in some areas may find it better to flee to safer ground rather than build ever-more-expensive defences against these onslaughts.

It’s a process that AR Siders, a disaster researcher specialising in climate-change adaptation at the University of Delaware, US, calls “managed retreat” in a paper published with colleagues in the journal Science.

“That has not gotten much attention,” she says, “[because] it’s been treated like a last resort, an option that people will only go to in total crisis.”

And since retreat sounds too much like defeat, managed retreat does indeed sound drastic. But it’s already being put into practice in some parts of the world.

Indonesia, Siders says, is considering moving its capital from Jakarta, a coastal city facing massive flooding by 2050. And the low-lying Pacific island nation of Kiribati, whose entire existence is threatened by sea-level rise, has purchased land in Fiji in order to give its residents a chance to relocate – something it calls “migration with dignity.”

On a smaller scale, the US city of Houston has purchased and demolished 3000 homes to make more room for high waters, in the wake of recent flooding from hurricanes.

But managed retreat doesn’t have to be that drastic. At the simplest level, Siders says, it can be done by regulating the ways people can rebuild after disasters, including such simple rules as increased setbacks from rivers, oceans, or brush lands susceptible to wildfire.

It can also involve helping people, or entire communities, relocate after a disaster, or halting development in areas that will ultimately have to be abandoned. “Why build more houses that we have to relocate 30 years from now?” Siders asks.

In the US, she says, retreat has primarily been done by purchasing homes at full market value – a potential long-term problem. “It would be less pricey if we do things like stop building in at-risk areas,” she says.

Margaret Walls, an economist at Resources for the Future, in Washington, DC, who was not part of Siders’ team, concurs. But the problem, she says, is complicated by economic pressures.

In a free-market economy, people have the right to own property. Beachfront, riverfront, and edge-of-the-forest properties are desirable, and therefore expensive. They also contribute the community’s tax base, making the local community unwilling to zone them out of existence. “So there’s this perfect storm of factors that makes this really difficult,” she says.

There are also problems of equity and social justice, Walls says – adding that this is a point that Siders also makes. “People who can move have the resources—money, and the ability to get a job in a new location,” she says.

Those who are left behind are the most vulnerable.

Worse, she says, as the rich see the writing on the wall and move away, property prices will drop, inducing the poor and vulnerable to move in. “Why do you have poor people living near refineries?” she asks, as an analogy. “Because property values are lower, and that’s where they can afford to live.”

Other scientists see managed retreat as part of the larger problem of figuring out how to adapt to a warming world.

“Efficient adaptation greatly lowers the total costs,” says Richard Alley, a climate researcher at Pennsylvania State University in the US.

Herculean efforts to defend expensive real estate, he adds, can actually make things worse, as might happen if massive amounts of money are spent in an ultimately futile effort to fortify coastal areas against sea-level rise. “People are reassured and invest more in those protected areas,” he says. “Then protection fails.”

In a recent paper, Alley’s team talks about how wise patients manage their health.

“[I]f a doctor tells you that you have an increased risk of heart disease, it might be prudent to adapt your behavior initially by moderately modifying your diet and exercise habits while leaving open the option to use more intensive approaches, such as prescription medication, if your perceived risk does not decrease sufficiently in the future,” they wrote.

Siders’ team believes that what’s called for is a “spirit of experimentation: a willingness to try new things paired with rigorous research and evaluation”.

Contrib ricklovett.jpg?ixlib=rails 2.1
Richard A. Lovett is a Portland, Oregon-based science writer and science fiction author. He is a frequent contributor to COSMOS.
  1. https://science.sciencemag.org/cgi/doi/10.1126/science.aax8346
  2. https://www.dw.com/en/indonesia-ponders-plan-to-move-capital-from-jakarta/a-50046272
  3. https://eos.org/opinions/investing-in-science-to-improve-climate-risk-management
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