Turning ‘managed retreat’ research into practice ready tools: needed guidelines to reach stakeholders


 The study of “managed retreat” as a response to climate change impacts has emerged in recent years as an important field of inquiry that is in need of substantial further research and improved understanding—particularly in the United States (Dundon and Abkowitz, 2021; Plastrik and Cleveland, 2019; Hino, et al., 2017; Dachary-Bernard, et al., 2019). However, the critical participant stakeholders in managed retreat discussions—often city/county planning officials and community members in vulnerable areas—often do not have adequate access to meaningful planning information or other tools to support decision making. With some notable exceptions, important research in this field that could assist communities is often relegated to academic journals that are not often visited by city or county planners faced with the very decisions this research could inform. Although the realities of research careers often require a focus on publication in prestigious academic journals, more attention is now needed to get actionable research knowledge in the hands of the practitioner. The need to develop user-friendly tools that direct research information into the hands of stakeholders most likely to benefit from such work is even more urgent than ever: climate change presents current, continuing, and substantial challenges for humanity in nearly every sector of the economy. Many extreme weather events have already increased (in frequency and/or severity) because of our changing climate, including flooding, heavy precipitation, extreme heat, and other climate-induced events (U.S. EPA, n.d.).


Introduction
The study of 'managed retreat' as a response to climate change impacts has emerged in recent years as an important field of inquiry that is in need of substantial further research and improved understanding-particularly in the United States (Hino et al 2017, Dachary-Bernard and Rey-Valette 2019, Plastrik and Cleveland 2019, Dundon and Abkowitz 2021).The phrase 'managed retreat' is perhaps most often associated with the intentional removal of people or infrastructure away from coastal areas that are vulnerable to impacts from sea level rise and storm surge.(Dundon and Abkowitz 2021).Prior research has examined in detail the variety of meanings associated with the phrase 'managed retreat' that can differ across cultures, geographies, and time (Ibid.).For example, in the United Kingdom, historically the phase is most often associated with an effort to restore coastal land to its natural state to reduce flooding impacts (Townend et al 2002).Over time, however, managed retreat has expanded to encompass a wide range of transformative responses to climate change, including moving people and assets away from areas of higher risk to areas of lower risk (not limited to coastal risks) (Ajibade et al 2020).The term is often used synonymously with 'strategic' retreat and is intended to cover 'a suite of adaptation options that are both strategic and managed' as a response to the increasing frequency and severity of a range of climate change impacts across a range of geographies (Siders et al 2019c).
However, the critical participant stakeholders in managed retreat discussions-often city/county planning officials and community members in vulnerable areas-often do not have adequate access to meaningful planning information or other tools to support decision making.With some notable exceptions, important research in this field that could assist communities is often relegated to academic journals that are not often visited by city or county planners faced with the very decisions this research could inform.Researchers have recognized this barrier and the need to get practice ready tools in the hands of planners with the authority and power to implement best practices that are often identified in the research (Hull 2008, Kent 2022).Indeed, the United Nations Secretary-General's High-Level Advisory Group on sustainable transport described the progress of an 'innovation chain' that relies on moving basic research through various stages towards implementation and commercialization (in the private sector) (United Nations 2016).Indeed, the United States Environmental Protection Agency implicitly recognized the need for additional practice ready tools to support local planners in sustainability outcomes when it developed the 'tools and resources for sustainable communities' (U.S. EPA 2023).
Nevertheless, perhaps because managed treat is both an emerging area of robust research and an often controversial adaptation approach, practical tools and resources are still in need of being developed that reach local and community planners with decision making authority.Indeed, this challenge led directly to the development, by Georgetown University's Climate Center, of the Managed Retreat Toolkit (GCC n.d.).Indeed, the lack of practical guidance on best practices and emerging research on managed retreat has led in part to a trend, documented by some researchers, of continuing investments in long-lived infrastructure that may increase community vulnerability to climate change (Shi and Moser 2021).Although the realities of research careers often require a focus on publication in prestigious academic journals, more attention is now needed to get actionable research knowledge in the hands of the practitioner.
The need to develop user-friendly tools that direct research information into the hands of stakeholders most likely to benefit from such work is even more urgent than ever: climate change presents current, continuing, and substantial challenges for humanity in nearly every sector of the economy.Many extreme weather events have already increased (in frequency and/or severity) because of our changing climate, including flooding, heavy precipitation, extreme heat, and other climate-induced events (U.S. EPA n.d.).Among critical infrastructure sectors, transportation is a notable example of the impacts of these events.Transportation planners, local governments, and others responsible for building, maintaining, and even insuring and financing expensive and long-lived infrastructure are keenly aware of the need to adapt.Indeed, there is substantial literature documenting climate change resilience adaptation efforts ongoing around the globe involving transportation and other sectors (Shi 2020, Tonn et al 2021).Planners now recognize that the risk profile of assets exposed to such extreme weather events has permanently changed.In some localities, adapting in place will not be affordable or even possible, and the only viable option may be to 'retreat' or remove the infrastructure asset, and potentially the communities that rely on that asset, to a new, less climate-sensitive location.This adaptation strategy is most often referred to as 'managed retreat,' but also 'transformative adaptation,' 'managed relocation,' or 'strategic retreat' (Dundon and Abkowitz 2021).Under any name, it is a bourgeoning topic of emerging inquiry, and an area that will need substantial additional study in the years and decades to come.
Several researchers, including the current authors, have documented approaches and case studies to managed retreat that are intended to be useful for considering, planning, and implementing a managed retreat strategy.This work identifies critical issues of social and environmental justice, human behavior, and implementation challenges that represent critical and insightful knowledge (Hanna et al Research has also demonstrated the importance of a thoughtful and considered approach to communication, which can be the pivotal factor to determining whether a managed retreat policy response succeeds or fails (Bragg et al 2021).In particular, Shi and Moser (2021) have documented a worrisome trend of increasing infrastructure investments that may actually exacerbate climate vulnerability and contribute to climate injustices (Shi and Moser 2021).Main et al (2021) have also developed unique methods that encourage and enable interdisciplinary collaborations among the very stakeholders that will need to increasingly come together to inform land use planning and urban design.However, many of these studies are often published for an academic audience and are not often in a form that is most useful for transportation planners and community practitioners.
The approach described herein aims to fill that gap, with a particular focus on transportation infrastructure planning.Drawing on our own research and perspectives of an emerging consensus among managed retreat researchers regarding the most salient issues in managed retreat decision-making, we present a comprehensive managed retreat framework (MRF) intended to convey in a flow chart form key considerations and processes.The framework consists of two sequential components: (1) the decision of whether to retreat, and then if a decision to retreat has been made, (2) how to plan for implementation.
While the intended audience for the MRF, as described and illustrated, is primarily local transportation planners at the city, town, or county government level, the structure and logic flow is expected to be applicable in many different contexts and could be helpful to a broad and diverse range of stakeholders.While it is not meant to be the only decision-support tool applied in any given circumstance, we believe it provides an important and user-friendly means for planners to navigate through this often complex process.Importantly, it is designed to assist planners to identify and potentially strategize around barriers to implementation before they arise.While the MRF presented here is informed by, and therefore focused on, the authors extensive research experience in risk as it relates to transportation infrastructure and planning, such frameworks are increasingly needed in a broad range of disciplines.

Example frameworks
Figures 1 and 2 depict the aforementioned framework involving the respective decisions of whether to retreat and how to plan for implementation While not every item on these flowcharts will be relevant to every interested party, the approaches represent an adaptable format that can aid communities in considering-and planning for-the benefits and challenges likely to arise when considering managed retreat actions.The steps documented in Figures 1 and 2 were collected and adapted from a wide variety of relevant literature cited herein (see e.g.GCC n.d.), including case studies (Kool et al 2020), but also emerge from the authors' own views and experiences, in particular in working with local and state transportation agencies and municipalities in addressing climate change impacts to infrastructure, and retreat planning and decision making.Future work in other fields could follow a similar approach, collecting and assembling into an easy-touse framework the primary relevant considerations  that have emerged in the academic literature, but also from practioner-focussed non-governmental organizations, in the respective field.
Figure 1 represents a framework for early stages of determining the potential for managed retreat as a policy response option to a particular climate impact or stressor.This specific example is aimed at a decision of whether to move or remove an individual piece of public infrastructure, such as a road or a bridge, but could be easily utilized in a wide range of managed retreat planning scenarios.The framework with an assessment of whether the asset has experienced prior loss and damage from extreme weather.See figure 1.This initial understanding is important in determining the potential financial cost to a community of continuing to rebuild in place (Tonn et al 2021).If continued or future climate impacts are expected, the user is directed through a series of considerations, including whether adapting in place may be feasible.If retreat needs to be considered, the framework then identifies specific factors (such as equity or cost impacts of a managed retreat decision) that can further inform whether retreat may be appropriate depending on individual circumstances.
If, based on the considerations identified in figure 1, a decision to consider retreat is reached, figure 2 can then be utilized to provide guidance to planners, communities, and other stakeholders on the types of retreat mechanisms that may be considered and the planning processes and elements necessary to facilitate a successful retreat strategy.Evaluation of some of these factors may lead a community to reverse its decision to pursue retreat; for example, in the case of publicly owned assets such as roads or bridges, the government may have a legal obligation to upkeep and maintain the asset, including constant rebuilding after storm events despite costs.Figure 2 assists planners to understand possible barriers early in the process, and provides greater potential to develop strategies in advance that may be needed to overcome such barriers.

Conclusion
While the framework we have introduced is not intended to account for every factual element that a community or planner may address when considering managed retreat, it represents an important effort at synthesizing and disseminating available knowledge in a systematic and structured fashion.The characteristics of different communities, asset types, and exposure levels to different climate stressors will of course dictate the needs and approaches of any particular decision on managed retreat.
Despite critical knowledge emerging in the last 5-10 years, substantial future work regarding managed retreat is still needed.This is true with respect to all facets of managed retreat, including communication methods, likely human responses, and the phenomenon of 'place attachment' that can be a barrier to retreat solutions (Agyeman et al 2009).Taxpayers bear a huge financial burden of the impact of extreme weather events on both public and private infrastructure-whether directly through increased private insurance premiums or the increased cost of public maintenance or costs of responding to extreme weather events.Managed retreat research is sorely needed to better inform when communities should continue to invest in restoration and when relocation may be the best response.
In 2022 alone, the U.S. experienced over $165 billion in damage from extreme weather events (this is a low estimate because it only includes the total from events that individually caused $1 billion in damage or more) (Smith 2023).This is a trend that is steadily increasing, in part because disasters are becoming more frequent or more intense due to climate change.Improved methods for identifying costsboth economic and non-economic-and translating them into meaningful and relevant information for community stakeholders can better inform the decision of whether to retreat.
Research is also needed at all scales to inform managed retreat decision making regarding individual assets, to the community and even nationstate level.Relocation of entire communities within the U.S. from Louisiana's Isle de Jean Charles to native Alaska villages has already occurred.Entire island nations in the Pacific Ocean see the livability of their homeland under threat, and some human migration can now be attributed to climate-induced impacts (Zeya 2022).Society will benefit from increased understanding of how managed retreat can be successfully implemented to improve human livelihoods, and from a continued increase in the development of tools and frameworks that widely disseminate that knowledge in a practical manner.
Because the focus of this framework is on practiceready solutions, we would like to especially acknowledge the work of the Georgetown Climate Center (GCC) in developing GCC's Managed Retreat Toolkit (GCC n.d.), and which informed the development of our Framework.Like the attached Framework, GCC's Toolkit was developed with practice-ready application in mind.After determining which aspects of the attached Framework may be most applicable to a particular circumstance, the GCC Toolkit can serve as an important reference to provide more detail on key decision points, as well case studies that planners may wish to consult.The work presented in this paper was supported by the U.S. Department of Transportation under Grant Award Number 69A3551747130.The work was conducted through the Maritime Transportation Research and Education Center at the University of Arkansas.

Figure 1 .
Figure 1.Managed retreat framework-the decision to retreat.