The projected impacts of climate change combined with legacy development and urbanization means that more people and assets will be exposed to natural hazard risks over the coming decades. Some of these risks can be calculated and managed effectively, particularly in the short and medium term, by technical approaches designed to protect people and assets. This strategy typically seeks to scientifically characterize and quantify risks, and translate this data into language that is useful for policy and practice, such as probability assessments, cost–benefit analyses, or confidence/likelihood thresholds. However, as the projected costs of protection or damage rise, and the difficulties in predicting long-term futures become more evident, governments and communities around the world are beginning to recognize managed retreat is an important approach to reduce risk and build resilience over the long-term [1
Managed retreat can be defined as a deliberate strategy to remedy unsustainable land use patterns that expose people, ecosystems, and assets to significant natural (and socio-natural) hazard and climate change induced risks [8
]. The benefits of this strategy stretch beyond risk management to also include the restoration of land and ecosystem functions, and the removal of long-term risk management liabilities and emergency management costs. The strategy can be applied to a range of risks across varying spatio-temporal scales, and encompasses planned relocation of entire communities, strategic realignment of critical infrastructure, and more site-and asset-based, responses [1
]. It holds potential to create more equitable and sustainable outcomes compared to ad-hoc, reactive or unmanaged relocations, such as those associated with migration and displacement, or in comparison to at-risk communities remaining in situ but subjected to an uncertain future with the prospect of escalating risk and declining investment.
While managed retreat has a compelling scientific logic, in practice it has many social, cultural, political, institutional, and economic challenges. For example, controversy often surrounds the approach due to the impacts of detachment from place, the strong desire to protect property rights and maintain the status quo, large up-front costs, logistical intricacy, and the political propensity to favor easier short-term fixes over more difficult longer-term resilience options [1
]. Managed retreat can also be socially and culturally disruptive, and may actually increase, rather than reduce, vulnerability. Further, the complex power and social relations between land, people and risk means the governance of managed retreat is highly complex, involving multiple stakeholders with manifold interests. In short, at risk communities and their governing authorities face a dilemma. On the one hand, remaining in situ enables people to pursue their livelihoods and retain cultural, social and place-based community ties. However, then they may be predisposed to severe harm and even disaster. On the other, managed retreat can eliminate place-based exposure to harm. However, livelihoods may be disrupted, and community ties broken. To compound matters, the prospect of future harm is invariably shrouded in layers of uncertainty. While we can be certain risks will increase, it is hard to predict when, where and how fast this may be manifest. It is no surprise that in this ambiguous socio-political environment, despite significant investment in scientific data to increase confidence, attempts to implement managed retreat invoke public dispute and litigation [1
While the managed retreat dilemma is typically positioned between the compelling scientific risk reduction imperative and substantial political unpalatability, in this paper, we seek to reframe this dilemma as involving more complex relations between multiple intersecting uncertainties, which we argue provides deeper explanatory power and new insights about its potential resolution. Although there is considerable attention within disaster and climate research on ways to address the scientific uncertainty associated with responses to extreme events and climate change, such as confidence levels on probabilities of hazards or climate futures, this technical uncertainty is intertwined with equally complex social, cultural, political, institutional, and funding uncertainties. In practice, managed retreat provokes vexing questions, such as the ‘right’ timing for retreat to occur; the most suitable place to relocate to; or who should pay and how much. These are not simple questions that can be solved by more knowledge concerning future climatic behaviour; they are complex questions rooted in divergent values, needs, and interests that differ spatially within and between countries and communities. Put differently, these questions go well beyond scientific
risk and uncertainty. There is significant “governance uncertainty as to how communities and governments will implement adaptation” [18
] (p. 205). As such, realizing the potential contribution of managed retreat as a resilience strategy necessitates better understanding about the intertwined uncertainties and wider political risks that become visible as managed retreat experiments unfold in diverse local settings from Alaska to Australia and New Zealand [5
This article repositions the managed retreat dilemma and consequent inaction from being less a scientific or managerial problem—about a lack of data or policy—to be a relational challenge. This reframing highlights the uneven ways that diverse ‘uncertainties’ become known or can be known, their varied power, and the ways they are responded to, whether in formal institutional arrangements or through lived experiences. It also brings to the fore their compounding interplay, which indicates the need for deeper understanding about the relational nature of the governance challenge. We identify and analyze the intersecting uncertainties surrounding the governance of managed retreat using a real-world case study, yielding insights for both practice and theory. For practice, we identify the selective ways by which diverse uncertainties become visible within both the scientific and governance arenas, and the ways these exhibit compounding and cascading effects that inhibit action—or if action ensues, explains why action is met with resistance. Significantly, these arenas are trans-disciplinary in nature, with each requiring diverse knowledge and ‘joined up’ praxis to reveal and address their interconnected uncertainties. For theory, in situations showing significant ‘wickedness’ like managed retreat, we recommend a shift away from the traditional focus on uncertainty as a subject of knowledge—a means by which a phenomena is quantified or reduced—towards uncertainty as an object of knowledge—how it becomes known and by whom—which we argue is critical to understanding the difficulties in translating and integrating multiple knowledges, including the underlying science, local and traditional knowledges, into action. Together this perspective foregrounds a relational understanding of managed retreat that reflects the interacting and compounding nature of manifold uncertainties associated with it—the uncertainty contagion—and the ways that inaction in one arena may not be resolved by action in another.
2. Materials and Methods
The methodology involved a case study of Matatā, a small rural coastal community in the Bay of Plenty (BOP) region on the North Island of New Zealand. This site was chosen as it is the location of one of the few attempts to implement a managed retreat strategy in the country and, as such, reveals the dilemma-laden nature of this strategy, and the associated uncertainties and implementation challenges. In May 2005, a torrential downpour triggered landslips, flooded the nearby Awatarariki stream and catalyzed debris flows that destroyed 27 homes and damaged a further 87 properties in the township [24
]. Since that time there have been ongoing discussions, investigations and negotiations between the authorities, experts and the community concerning the preferred risk management approach. This process eventuated in a local government decision to activate managed retreat from the Awatarariki debris flow fanhead some 14 years after the initial disaster. As there was no suitable New Zealand precedent to draw upon, the town became a site at which the many dilemmas, uncertainties, and perspectives on managed retreat were brought into sharp focus.
The research initially involved a desktop analysis of the key planning provisions that established the framework for decision-making, the supplementary technical risk reports that provided much of the evidence base for action, and the media coverage related to the situation. This regulatory, institutional and media focus was complemented by 17 semi-structured interviews involving members of the community living within the high-risk zone, as well as technical experts, politicians, and council staff charged with the responsibility to reduce the risk. The interviewees were selected via a purposive sampling approach and snowball strategy [25
] designed to capture the diverse perspectives from the differing key actors and agencies directly associated with the case. Three broad groups were identified: involvement in governance, policy or project roles, for example, consensus development groups, regional and district council staff and politicians; technical and scientific experts related to the calculation of risk and uncertainty; and members of the community who are property owners within the high-risk zone or mentioned in media releases from 2005 to 2017. Selected participants remain anonymous, but include environmental planners, technical experts and project managers, politicians, affected community members and an iwi (Māori tribe) representative.
The interviews afforded rich interpretive data to provide insights about decision-making processes, the political issues at play, and the human costs that accumulated as uncertainties were compounded and prolonged. While the interviews were semi-structured, given the lived experiences and feelings associated with this high-profile case there were also open-ended questions to allow for flexibility and expression of thought [26
]. The structure and content of the interview questions focused on understanding the roles and experiences of participants, revealing their decision-making logics and rationales at each step of the process, how they responded to uncertainty, and the key barriers, enablers and lessons learned. Where consent was given, interviews were digitally recorded, and notes taken. Prior to conducting the interviews, the aims of the research, its scope, and ethical considerations were discussed with participants, who all gave their informed consent. The data was inductively coded, with each document and interview transcript organized thematically according to key words, phrases and topics.
Together this research design enabled insights into the suitability of prevailing decision-making frameworks, the ways that these were interpreted and implemented, and the economic, political, cultural, and social issues at play. More explicitly with regard to this article, it also shed light on the multiple, intersecting dimensions of uncertainty; and how an uncertain governance framework created cascading social, political, institutional, and funding uncertainties. The nature of these uncertainties contributed to protracted post-disaster trauma for the communities who remained in limbo, and at risk, 14 years later.
3. The Certainty of Managed Retreat in an Uncertain World
We now draw upon uncertainty literature to reveal the difficulties decisionmakers face in enabling managed retreat. This is delineated into two specific areas: first, how uncertainty becomes known, by whom, and how; and second, how this knowledge subsequently elicits a response, e.g., within a policy setting, or prompts more scientific investigation or innovation in praxis. These considerations are important because they can advance understanding about the relationship between the production of science and its impact upon practice, which is at the very heart of the managed retreat dilemma.
The increasing involvement of social scientists in research on climate change and natural hazard risk over the last few decades has driven new understandings regarding uncertainty as a concept and as a governance challenge. The IPCC provides a valuable foundation for unpacking how scientific uncertainty has been framed, by whom, and how this is communicated within and between scientific and policy realms. In the assessment reports we see the gradual emergence of the main concerns and the preferred response strategies, for example, the growing use of multiple models, or multiple strands of evidence beyond models, the linking of observations and models, the rise of expert judgement to help narrow uncertainty ranges, the construction of future scenarios, and the use of precisely defined language to convey the assessed likelihood of an outcome. These issues similarly underpin managed retreat deliberations in the face of climate change which, as a starting point, invariably involves a scientific calculation of the level of risk that prevails in a locality, and is typically ascertained by modelling inputs and technical risk assessments [27
]. These reports also help to highlight different dimensions
of scientific uncertainty, such as technical, methodological, epistemic and aleatory sources of uncertainty. For instance, epistemic uncertainty is the imperfection of knowledge (also termed completeness, subjective, or systematic uncertainty), and aleatory uncertainty represents the inherent randomness of human and natural systems that cannot be reduced (also referred to as variability, stochastic, random or ontic uncertainty) [27
]. Unlike aleatory uncertainty, epistemic uncertainty can be quantified and mitigated, but even then new information can reveal new uncertainties [27
This discussion of knowledge and uncertainties about what is and can be known is useful because it brings into focus the influences of the professions and disciplines that have traditionally been involved in the risk and uncertainty fields, where modelling and engineering have played a strong role, and which are gradually becoming more influenced by the social sciences. It also highlights the long-standing science-policy logic that seeks to increase confidence concerning future risks so that decision-makers can be more confident in responding in the present [32
Knowledge is not, however, simply a process of gradually accumulating evidence and confidence, or understanding variability. New science can uncover fresh issues and insights, while uncertainty ranges may even widen as a result of new data. For example, within the natural hazard and climate fields, science is uncovering new dynamic system feedbacks, a deeper understanding of compounding and cascading risks, and the complex interactions between and within natural and social worlds [33
] Meanwhile, within the social sciences, increasing attention is being focused on the political nature of science, its selective construction and representation, and the problematic ways careful caveats can be eroded in the transition from science to policy [37
]. Moreover, there are active lobby groups producing competing knowledge claims, the rise of post-truth politics, more awareness about the role of ideology and values, and even the emergence of new theoretical concepts, like agnotology, which seek to better understand the deliberate
production of uncertainty to inhibit confidence in public policy [41
]. While there will always be a role for scientific knowledge as an authoritative way to calculate risk and assess uncertainty, the increasing technical complexity also means that scientific assessments of uncertainty can be subject to ‘black-boxing’, a process whereby the inner workings are difficult to understand, even by other experts, which has wider implications for social justice, and public understanding and scrutiny [37
Given the inherent difficulties in revealing and managing uncertainties, increasing attention has been focused on how it is conceptualized. Rather incongruously, uncertainty is both fundamental to any scientific endeavor and is an amorphous and ambiguous term in its own right, due to its diverse applications in theory and practice. Academic scholarship aiming to reveal different typologies of uncertainty helps reveal new dimensions and arenas beyond a simple deficit of data or confidence. These nuanced perspectives blur the delineation between environmental and process uncertainty [43
] for decision-making, or may also question the simplistic ‘tame-wicked’ binary [44
] associated with difficult decisions. For instance, in a review of environmental risk assessments, Skinner and colleagues [27
] (p. 213–214) identify a concern regarding how uncertainty becomes known and understood by revealing inconsistencies and contradictions in the use of terminology and dimensions of interest between similar technical assessments. They develop a taxonomy that categorizes uncertainty into two main types (epistemic and aleatory), seven location-based types (system processes, data, model, human, language, variability and decision) and a further five levels of uncertainty (determinacy, statistical, scenario, ignorance and indeterminacy). Other typologies highlight the difference between fields of uncertainty. These include, for instance, geopolitical, financial, institutional, spatial, strategic, and climate change uncertainty [27
]. With particular relevance for managed retreat, Walker, et al. [51
] point out that decision-making associated with the distant future is beset by uncertainties that cannot be reduced by information gathering and statistical analysis. Such situations have been characterized as having ‘deep’ uncertainty where agreement is difficult on which model to use, how uncertainty should be represented, or the desirability of alternative outcomes [52
]. This perspective seeks to address uncertainty by linking the inevitably partial evidence base with strategies to build adaptive capacity of socio-ecological systems, enhancing flexibility to adjust to dynamic conditions [53
Revealing the complexity of uncertainty underscores its many dimensions, from a basic lack of information to what can even be knowable, the variety of means by which these could or should be mitigated, and deepening understanding about the intricate interrelationships between academic disciplines and their suitability towards revealing and understanding different dimensions of uncertainty. These insights also underscore how different approaches to conceptualizing uncertainty can lead to very contrasting methods, tools, and demands for practice [31
This theoretical reflection begins to deepen the understanding of real-world managed retreat decisions, and the vexing political and institutional questions that inhibit action, such as how managed retreat will be implemented, by whom, when, and at whose cost? To extend the uncertainty discussion, issues in this arena can result from ambiguity surrounding responsibility, laws, direction, coordination and capacity to act. Therefore, in addition to scientific uncertainty, composite problems such as managed retreat, which cross multiple disciplines and face many implementation challenges [8
] are constrained by institutional uncertainty [1
]. As recognized by Koppenjan and Klijn [50
], this can result in a high degree of doubt about how the process could or should unfold, the interactions between actors, and who is responsible for action. Institutional uncertainty can be difficult to overcome due to how existing frameworks are “anchored in formal legal frames, deeply-rooted informal institutions or long-term societal transition processes” [50
] (p. 7). A further dimension of concern is the question of ‘managed retreat to where?’, which challenges implementation prospects, effectiveness and sustainability, causing extended ‘waiting’ and temporal uncertainty about the future for affected people and communities.
This section is designed to emphasize that while there has been a tendency to consider uncertainty in the context of specific issues, or thematically as a scientific problem to be mitigated, uncertainties are complex, multifaceted and interdependent. This is, in part, due to the nature of decision-making where, for example, scientific and economic uncertainty can lead to or compound political uncertainty and inaction. This repositioning of uncertainty as comprising mutually dependent scientific and social dimensions suggests there is merit in refocusing attention towards the relations between different forms of knowledge and their application in practice. Put differently, research has tended to consider uncertainty as a research subject, a means to quantify and increase scientific confidence within discrete arenas; however, the implementation difficulties of managed retreat suggest that uncertainty could also be recast as a research object, worthy of focus in itself, to better capture its multi-faceted, compounding, and interrelated nature of risk and response. The following sections are designed to advance this reframing and deepen understanding about both the interplay of uncertainties between science and society, and within the various arenas of managed retreat decision-making and praxis. Insights gained by interrogating the Matatā experience may inform managed retreat efforts in other localities in New Zealand and elsewhere.
4. The New Zealand Governance Setting for Managed Retreat: A Gradual Revealing of Multiple Uncertainties
We start our analysis by revealing the various governance uncertainties that were in evidence as the Matatā situation unfolded. In New Zealand, the responsibility for managing the effects of natural hazards and adapting to climate change is devolved to local government. In practice, however, the task is inherently political involving local authorities, elected officials, affected people, sectors, and communities, iwi, banks and lending institutions, utilities, infrastructure and insurance sectors. Primary mechanisms for retreat interventions include provision of information, regulation, incentives and disincentives, and risk transfer, with regulation and incentives being key to deliver action [8
]. Managed retreat provisions are present in the New Zealand Coastal Policy Statement 2010, and it is considered, promoted, facilitated, and required in various ways in both regulatory and non-regulatory stipulations [56
]. However, in reality, the regulatory framework is not designed to deliver managed retreat, and has no funding to support it [57
]. The conceptualization and impact is evolving in response to influences of escalating risk, the consequences of extreme events, information provision, insurance retreat, evolving local policy and regulation, limited use of compulsory or negotiated land acquisition under the Public Works Act 1981 (delivering managed realignment), pilot strategies, and ad hoc government interventions and community actions.
The various retreat options can be conceptualized as situated on a spectrum between strong government intervention on one end and anarchy on the other, where people are left to respond to risk themselves; or in simple terms, from managed to unmanaged retreat [56
]. In New Zealand, the decision-making framework for managed
retreat rests predominantly with environmental planning and the mandated promotion of sustainable management of natural and physical resources under the Resource Management Act 1991 (RMA). However, as there is no single pathway to or any preferred version of retreat, the scope of possible actions effectively fosters an environment of uncertainty, as who is responsible and how managed retreat should occur varies significantly according to context and circumstance.
Under s 62(1)(i)(i) RMA, regional councils delegate the responsibility of land use control for natural hazard management to territorial authorities (i.e., district and city councils) in their respective regional policy statement (RPS) (with general exclusions for the coastal marine area, the beds of rivers and lakes, and some joint responsibilities). Territorial authorities, using district plan controls over land use activities can limit new and re-development (intensification, extensions, additions, and activity status change) in areas subject to natural hazards and the influences of climate change. In addition, this includes providing for future managed retreat (where appropriate) using relocatable building design with monitoring and review of consent conditions to safeguard and facilitate future relocation. In contrast, while there are opportunities to regulate new land uses and encourage managed retreat over time, where development already exists, territorial authorities have very limited agency as many activities have existing use rights. However, under s 20A of the RMA, if it is within the scope of a regional council’s functions, it may be possible to apply regional rules to regulate managed retreat by extinguishing existing land-use rights.
Therefore, whilst managed retreat (as a form of land use control) aligns with delegated territorial authority functions, only regional councils hold powers to enforce it for existing development, creating a jurisdictional problem that generates confusion and uncertainty for practitioners. In an attempt to address this conundrum, three regional councils explicitly recognize the jurisdictional overlap and relevant functions in their RPSs. While these councils have attempted to reduce institutional uncertainty regarding roles and responsibilities, there are still political challenges in practice, as will be discussed in Section 5
. In addition, there is a degree of legal uncertainty regarding compensation for regulatory takings (extinguishment of existing use rights) due to a lack of precedent and case law.
Although there are difficulties in achieving managed retreat of existing development using planning regulation, some councils have been able to achieve it using negotiation or compulsory property acquisition under the Public Works Act. However, this approach requires some form of public work, such as a stop bank or sea wall, and is, therefore, more correctly termed ‘managed realignment’, being a deliberate alteration to, or creation of, defenses, ideally in a way that restores natural space and enhances the capacity to cope with environmental fluctuations [9
]. Such property purchases have been occurring to manage inland flooding across New Zealand, for example, in Edgecumbe, Hutt City, and Waitakere, where willing buyer-willing seller negotiations were first attempted with property owners. The powers of the PWA were available to authorities (and declared to property owners) if owners refused to sell [58
]. However, property acquisition is difficult to achieve without a mechanism (or budget) to acquire land, unless public works are involved and the PWA is invoked. Nonetheless, there is legal uncertainty regarding whether land can be compulsorily acquired under the PWA for the creation of reserves, or whether land is only able to be purchased by agreement [20
]. In the case study of Matatā, Whakatāne District Council received legal advice that the PWA could not be used for managed retreat and subsequent reserve conversion, but, to confuse things further, the Resource Legislation Amendment Act 2017 (s 85(3A)(a)(ii)) suggests otherwise.
In short, despite managed retreat being possible under prevailing legislative provisions, there is limited national guidance on how to frame and implement it, when, or at whose cost. This is exacerbated by the scope of possible actions, whether site-based and incremental, or those requiring major strategic changes to land use. Such fundamental questions present multiple sources of uncertainty for both policymakers and affected parties. The implications of this uncertain governance framework were gradually revealed in Matatā as managed retreat became a political imperative, that then became subject to compounding uncertainties that essentially demanded a process of policy exploration and learning. This had consequences for both the planning regime and the people living in Matatā, who became the proverbial ‘guinea pigs’ and bore much of the costs of efforts to resolve the underlying uncertainties. The following analysis highlights the cascade of uncertainties that built up over time within the governance arena and provides insights about the real-world consequences.
In the case of Matatā, compounding and cascading uncertainties spread like a contagion and exacerbated the managed retreat dilemma. In the first instance, without a clear risk reduction and strategic recovery response framework to direct decision-making following the 2005 debris flow, WDC and the community became focused on absorptive resilience, seeking to bounce back from the extreme event, settling on a risk mitigation rationale when, in hindsight, managed retreat was the only viable option to deal with the ongoing risk to life. While the hazard mitigation method initially proposed provided fleeting assurance, this short-term certainty was traded for longer-term uncertainties and stress as the managed retreat imperative came to the fore, and implementation became fraught.
Developing and implementing a managed retreat strategy without adequate policy guidance, regulatory tools and funding provisions is nigh impossible. To enable managed retreat within the prevailing planning system, fit-for-purpose mechanisms and national support and policy provisions are necessary to provide direction, enabling institutional capability, and surety to affected parties, and the decisionmakers and practitioners responsible for managing retreat, and to reduce cascading political, financial, institutional, cultural and social risks. Managed retreat is not a cheap undertaking, requiring funds for risk assessment, community support and engagement, strategic planning, policy development, disestablishment of development and restoration of land, not to mention potential financial incentives and associated property valuation and negotiation processes. Limited local government capacity to attain funds to reduce technical uncertainty [4
], let alone undertake strategic, anticipatory adaptation and risk reduction planning, means that managed retreat is laden with risks for councils. Funding clarification is necessary to ensure legitimate, incentivized managed retreat, and to balance the social costs of relocation. Jones and Clark [78
] confirm that perceived social costs and benefits of policies influence levels of public acceptability, and that social capital parameters, including institutional trust, also have an impact.
Trust is important to achieve successful cooperation within and between spheres of government and communities at risk under conditions of uncertainty [50
]. It is an important feature of social capital, developing from relationships based on belief in the care, honesty, and good faith efforts of others, which can mitigate risk, and help address vulnerability based upon positive expectations of the intentions or behaviors of others [79
]. In attempting managed retreat, trust is essential, and is particularly delicate when actors are highly vulnerable to harm from intervening authorities. Koppenjan and Klijn [50
] recognize that inconsistent actor strategies and changing circumstances may negatively affect trust, as was also revealed in this case study as residents’ trust in authorities was diminished as a result of compounding and cascading governance, funding and socio-cultural uncertainties. While trust can help to overcome uncertainty [81
], when uncertainties are compounding and pervasive, trust between communities and their governing authorities may be undermined, reconsidered or dwindle altogether [50
In Matatā, the local council had to overcome many challenges to arrive at and deliver managed retreat in the absence of a guiding governance framework, regulatory tools and funds. The process of policy experimentation and learning resulted in contention between some of the residents and local government, enduring trauma, and stress for the community and staff involved 14 years on from the debris flow. While regional and central government agreed finally, in 2019, to co-fund the buyout, the ad hoc approach to managed retreat policy and funding are disruptive and inequitable, and create reactive strategies that are consistent with a fragmented risk management. These compounding uncertainties challenge the realization of managed retreat and increase the potential for cascading social costs and accumulating mistrust, aspects that may not be resolved by measures designed to increase scientific certainty. The prospect of uncertainty contagion is not limited to Matatā. Many other New Zealand communities, such as Mōkau, Marokopa, Kaiaua, Franz Josef, South Dunedin, Port Waikato, Hector, Ngakawau, and Granity, face similar challenges. Internationally, these multiple uncertainties associated with managed retreat also compound and cascade and hamper effective action [1
This paper has revealed multiple arenas in which uncertainty about managed retreat becomes manifest, and outlines how it spreads between what are very different albeit interconnected domains, from technical risk, to the governance arena with its funding and legal ramifications, to public acceptability, and the socio-cultural and political arenas. Significantly, we argue that to address the uncertainty contagion, the different arenas of uncertainty need to be revealed, and ‘joined up’ responses are required by different actors within different networks. The potential for multiple, cascading and compounding uncertainties underscores the inherent difficulty of enacting managed retreat in a coordinated fashion. There is an arena of scientific or technical uncertainty, where quantification is often invoked in efforts to clarify and contain the scope of uncertainty, or which receives new demands for authority in response to political or social uncertainty. There is an arena of governance uncertainty, where politicians, policymakers and practitioners, and governance actors more generally, clamor for clarity on direction, process and responsibilities. There is an arena of political and economic uncertainty where decisionmakers and communities strive with each other to secure agreement regarding compensation or incentives (not to mention potential damage claims and reparation [83
]). Finally, there are arenas of social and cultural uncertainty, where communities and individuals reflect upon and interact with others about their values, needs, and ethics associated with their connection to place and each other, their trust in authorities, and their willingness to accept or resist managed retreat. While a discussion of taxonomy is useful in demonstrating the scope of the challenge, we argue that the way that uncertainty spreads between domains means that a relational understanding of uncertainty needs to be developed to better comprehend and address the managed retreat dilemma. For example, in Matatā, governance uncertainty compounded political uncertainty, which was further compounded by financial uncertainty, which eroded public trust in both authorities, the underlying science and local government strategy. While, in situations like these, there may typically be a call for more technical data to increase scientific certainty and reduce political risk, it is clear that, on its own, this response would not reduce the considerable uncertainty manifest in other domains. Further, new dimensions of uncertainty may yet be discovered. For example, in New Zealand, attachment to place differs within and between Māori and other cultural groups, and much remains to be done to build shared understanding and enable tikanga Māori (customs) for retreat from Māori land.
The potential of managed retreat is hampered by concatenated uncertainties that can only be addressed if they are identified [27
], but they also need to be considered in relation to each other and addressed across different arenas—from the techno-scientific to governance, financial, spatio-temporal and socio-cultural—in a coordinated manner. The Matatā experience demonstrates that, in the absence of strong policy direction and ‘joined up’ praxis, uncertainty can spread like a contagion. Our perspective offers a new frame to understand the considerable difficulties experienced in implementing managed retreat in New Zealand and potentially elsewhere. While governance frameworks, and economic and socio-cultural settings inevitably differ, there is noteworthy commonality in the intersecting layers of scientific, institutional, financial and social uncertainty that bedevil managed retreat efforts in divergent settings from Alaska [5
] to Australia [16
] and New Zealand.
More broadly, our perspective highlights the value of conceiving uncertainty as a distinct research object in itself. Regardless of the context within which managed retreat is applied, there will inevitably be both scientific and governance uncertainties in evidence, such as the level of natural hazard risk and the level of political risk associated with questions such as how managed retreat is to be applied, by whom, at whose cost, when, and to where? Policy learning is occurring to progress managed retreat, but its socially disruptive nature means that every trial counts. At present, managed retreat interventions are professionally, politically, financially, culturally and socially risky, as the necessary frameworks and resources are seldom in place to support effective, equitable, responsive, and robust decision-making. Uncertainty over governance essentially means that these risks persist and, as such, may compound future risks, whether due to maladaptation or inability to adapt due to limited capacity to enable managed retreat. While managed retreat holds potential as a risk reduction approach, without acknowledging how scientific, governance, financial, political, spatial and socio-cultural uncertainties are entwined, and require distinctive but coherent strategies, the managed retreat dilemma will prevail.