Sea’ties (Ocean & Climate Platform) New Special Report “Managed Retreat: Preparing coastal cities to sea level rise”

By Sarah Palazot, Tess Segonds, Théophile Bongarts-Lebbe 23 April, 2025

Given the rapid rate of sea level rise, perhaps a 'managed retreat' is your best option. The Authors of The Ocean Climate Platform & Sea'ties latest report breakdown the pros & cons of this adaptation strategy

Sea levels could rise by >1m without drastic GHG cuts; Whilst several adaptation solutions are possible, a planned relocation or 'managed retreat' will sometimes be inevitable
It goes beyond protection & being a last resort; Its a transformative territorial project offering a chance to design a better future for coastal cities - but there's are multiple uncertainties to be aware of
In the US, managed retreat is foremost a question of social justice; Relocation should be integrated into natural life cycles like job changes & retirements; But also we need to learn from past experiences & plan ahead

By 2100, sea levels could rise by more than a meter without drastic reductions in our greenhouse gas emissions, according to the latest IPCC report. This global average encompasses diverse local realities for coastal cities, and many uncertainties remain. One thing is certain: cities must adapt immediately and sustainably.

Sea levels could rise by >1m without drastic GHG cuts…

…several adaptation solutions are possible but planned relocation or ‘managed retreat’ will sometimes be inevitable

Several adaptation solutions are possible and can be combined in space and time to meet local needs: planned relocation is one of them. Also known as managed retreat, this strategy, although complex to implement, will sometimes be inevitable. Unlike emergency management, it can be defined as a planned effort to permanently move people, buildings, and activities away from vulnerable coastal areas.

Because of its complexity, managed retreat is a topic which attracts much debate and resistance. To better anticipate, design, and implement this adaptation strategy, it is essential to bring about changes in narratives and to work towards a shared understanding of the issues and the methodologies that can accompany its deployment. With this in mind, the Sea’ties project (Ocean & Climate Platform), publishes a special report on “Managed Retreat: Preparing Coastal Cities for Sea Level Rise”. 

Intended for policymakers, and key stakeholders involved in the adaptation of coastlines, this special report proposes an in-depth analysis of managed retreat and methods for its implementation.

Five testimonies – from Guadeloupe to Martinique, through the Southwest of France, from Saint-Louis in Senegal to the United States – shed light on the key challenges of managed retreat.

They underscore that while the path of managed retreat is complex, it is not impossible and can even be an opportunity to profoundly and sustainably transform cities for the benefit of societies and biodiversity.

Why ? Choosing managed retreat as an adaptation solution

Managed retreat should not be seen as a last-resort solution or a failure of adaptation; rather, it is a proactive adaptation strategy in order to safeguard vulnerable populations. Given the significant economic, social, and environmental costs of maintaining infrastructure and populations in high-risk areas, managed retreat can often emerge as a more effective and sustainable solution over time. It is already in regions like Saint-Louis in Senegal. In this case study, Al Hassane Loum, Head of the Saint-Louis Municipal Development Agency, highlights the need for anticipating early enough managed retreat to avoid the unintended and often maladaptive consequences of emergency relocations. 

It goes beyond protection & being a last resort…

…it’s a transformative territorial project that offers a chance to collectively design a more desirable future for coastal cities

Managed retreat goes beyond simply protecting assets and populations; it is a transformative territorial project capable of driving social, economic, institutional, and environmental change. It offers an opportunity to collectively design a more desirable future for coastal cities. Examples from Petit-Bourg in Guadeloupe and Le Prêcheur in Martinique highlight the critical importance of engaging residents and all relevant stakeholders for gaining acceptance of these transformations, which have the potential to disrupt established lifestyles and reshape both individual and collective histories.

Where? Spatial scales of managed retreat

Risk exposure is the primary factor for determining relocation sites but choosing the appropriate responses requires a comparison of the social, economic, and environmental costs, at short, mid and long terms. Regarding destination locations, while proximity within the same city is often preferable, it may not always be feasible.

The main factor for determining relocation sites is risk exposure…

…appropriate responses require comparing social, economic, environ costs over short, mid & long terms

In any case, relocation frequently disrupts connections between territories and involves numerous stakeholders and levels of governance. The testimony from the Southwest of France, demonstrates the importance of coordinating managed retreat at all governance and geographic scales – from neighbourhoods to municipalities, municipal partnerships and regional councils, and up to governments – to ensure policy coherence and overcome fragmented initiatives.

When? Dynamic approach to managed retreat

Adapting coastal cities to rising sea levels involves navigating multiple uncertainties regarding both climate change and the evolutions of our societies. To meet this challenge, the scientific community and practitioners recommend a dynamic approach based on the concept of adaptation pathways. In this context, managed retreat is envisioned as a gradual process over time, progressing step by step towards large-scale relocations, thanks to transitional and supportive policies.

Illustration of a dynamic pathway to managed retreat

How? Pillars of a just and sustainable managed retreat

Managed retreat requires ambitious public policies, with appropriate governance frameworks, sufficient and long-term funding for municipalities. Importantly, social justice lies at the heart of every relocation effort. In the United States, cases such as Jean-Charles Island in Louisiana and Grand Forks in North Dakota illustrate how relocations not only expose but can also deepen disparities in power and wealth. A.R. Siders underscores the critical need to acknowledge and address these systemic imbalances. 

In the United States, like anywhere else, managed retreat is foremost a question of social justice

Around the world, communities are relocated from prone-risk coastal areas, either as an emergency response or – in still very rare cases – as a planned solution. Regardless of the circumstances, those relocated must be rehoused. Do such rehousing plans incorporate social justice? “There are far more cases where social justice is lacking than where it is upheld,” signals A.R Siders, associate researcher at the University of Delaware, USA, “but things are progressing”.

Sometimes pre-existing inequalities are exposed…

…e.g. on Isle de Jean Charles, federal regulations denied a Native community’s tribal status & blocked their rehousing…

…& low-income households often struggle to secure suitable housing

While managed retreat can create situations of injustice, it’s not necessarily the cause. Sometimes it merely exposes pre-existing inequalities. On the Isle de Jean Charles, off the coast of Louisiana, a Native community was relocated in response to rising sea levels exacerbated by nearby oil-drilling operations. Although the relocations were well prepared, federal regulations denied these communities’ official tribal status, thus impeding them from obtaining the right to be rehoused in the new town which had been designated for them. “In this precise case, the lack of social justice pre-dated considerably the question of relocation, yet it had a direct impact,” explains A.R Siders. A similar injustice occurs when displaced individuals receive financial compensation but are left to navigate the housing market on their own. While wealthier families can manage this transition, low-income households often struggle to secure suitable housing. “Once again, relocation often merely exposes existing social injustices.

Another place, a different example: a relocation plan organised in Grand Forks in North Dakota, USA, did indeed offer new housing but came to an abrupt end. “These houses were two to three times more expensive than the ones previously lived in,” reveals the researcher. “The people simply could not afford them. ”Most of the time the people running the rehousing plans do their utmost to help, but find themselves thwarted by a lack of funding.

Relocation should be integrated into natural life cycles, like job changes, retirements…

…we need to learn from past experiences & plan ahead

The objective is to plan ahead. In many places we know precisely what could occur in 20 or 30 years’ time. And yet, nothing is done until the disaster happens. “In the immediate aftermath, families are traumatised and in a great state of distress, sometimes having lost everything. Moreover, they must make the difficult decision to move out. This is not an effective approach. We must plan for the long term. Instead, relocation should be integrated into natural life cycles, such as job changes, retirements, or the desire to move to a different climate,  then resettlements could be achieved more smoothly.” It is obviously much easier to regularly help small groups of people to move house than it is to move an entire community in one fell swoop. “If we look at the example of Grand Forks, the idea of building houses was a good one. But by neglecting to think carefully about who they were being built for rendered the plan ineffective. We need to learn from these previous experiences.” Learn from past failures, therefore, to better manage retreat in the future

Author: Marielle Court

 

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Author: Sarah Palazot
Sarah Palazot is Project Officer for coastal adaptation and science mediation at the Ocean & Climate Platform. She holds an MSc in International Affairs from Sciences Po Bordeaux, France, and specialised in Environmental Policy at the Middlebury Institute of International Studies, U.S.A. At the OCP, she works on the Sea’ties project and has led publications translating key scientific reports, including the IPCC, for decision-makers on the interactions between the ocean, climate and biodiversity.
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Author: Tess Segonds
Tess Segonds is a Coastal Adaptation Intern at the Ocean & Climate Platform. She holds a Bachelor’s degree in Humanities – Law, Economics, and Management from the University of Paris Nanterre and was enrolled in a Master’s program in Environnemental Territorial Planning at the University of Strasbourg. She then pursued a Master’s degree in “Knowledge on Ecology” at Sciences Po Strasbourg and is particularly interested in cities’ adaptation to climate change.
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Author: Théophile Bongarts-Lebbe
Theophile Bongarts is Head of Coastal Adaptation at the Ocean & Climate Platform. He holds a master's degree in economic policy and agricultural development from the Université Panthéon-Sorbonne. At OCP, he was first involved in coordinating scientific activities, in particular the revision of the IPCC report on the ocean and cryosphere (SROCC) for the French and Monegasque governments. For the past five years, he has been coordinating the Sea'ties Initiative, dedicated to the adaptation of coastal cities to sea-level rise.
Read more from Théophile Bongarts-Lebbe →
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