Adapting to shoreline retreat: Finding a path forward

Abstract

Global sea level is rising at an increasing rate and communities and cities around the planet are in the way. While we know the historic and recent rates of sea level rise, projections for the future are difficult due to political, economic, and social unknowns, as well as uncertainties in how the vast ice sheets and glaciers of Antarctica and Greenland will respond to continued warming of the atmosphere and the oceans. It is clear, however, that sea level will continue to rise for centuries due to the greenhouse gases already in the atmosphere as well as those we continue to produce. A rising ocean leads to a retreating coastline, whether gradual inundation of low-lying shoreline areas or increased erosion of cliffs, bluffs, and dunes. Coastal armoring and beach nourishment have been the historical approaches to address coastal or shoreline erosion, but these are laden with economic and environmental costs, often short-lived, and have significant impacts on beaches; their approval by permitting agencies is also becoming more difficult, at least in California (Griggs and Patsch 2019) but also in a number of other states. Coastal communities and cities are already experiencing the impacts of rising seas and more will experience these impacts in the decades ahead. Many cities in California are beginning to discuss, consider, and plan for how they will adapt to higher sea levels, but not without controversy, especially concerning managed retreat. However, over the long run, they all will respond through relocation or retreat of some sort, whether managed or unmanaged. Sea level rise will not stop at 2050 or 2100. Effective adaptation will require a collaborative process involving many stakeholders, including coastal home and business owners, local governments, and state permitting agencies in order to develop and implement policies, plans and pathways for deliberate adaptation to the inevitable future. For many reasons, this is a complex problem with no easy or inexpensive solutions, but the sooner the science is understood and all parties are engaged, the sooner plans can be developed with clear trigger points for adaptive action, ultimately relocation or retreat.

Reframing strategic, managed retreat for transformative climate adaptation

“…Retreat has figured into disaster risk management and adaptation portfolios largely as a deprioritized, politically perilous option (7,15,20,32,33), in part because the motivation in most cases has been to avoid transformation: to enable people to continue living where and how they have in the past. Yet as climate conditions shift outside the bounds of CLIMATE-INDUCED RELOCATION historical human experience, the need for transformational adaptation that fundamentally alters systems will likely increase (5,9,11,14,35,36).…”

“…Other concerns, especially those about unintended harms, may be addressed by developing flexible pathways: steps bridging the present and future that allow for and even encourage revision (7,45,57). Current choices create path dependence and potential maladaptation, equally through conversations that are not happening right now as through those that are (20,22). For example, conversations about how to help shrinking settlements thrive or how to address historic injustices may be crucial for future adaptation responses, and these options may be limited because such discussions are currently inhibited by social or political risks.…”

“…For example, conversations about how to help shrinking settlements thrive or how to address historic injustices may be crucial for future adaptation responses, and these options may be limited because such discussions are currently inhibited by social or political risks. Key features of effective adaptation processes and decision support therefore involve: (i) flexible, diverse responses that can be adjusted through time; (ii) active monitoring and evaluation to guide necessary changes along the way; (iii) integration of local, Indigenous, scientific, and other scholarly knowledge to assess contextspecific risks; and (iv) meaningful public deliberation to promote learning, consensus building, conflict resolution, and fair and just responses (7,20,24,28,45,48,50,57).…”

“…Each adaptation action represents a distinct value-laden decision about what to preserve, purposefully change, or allow to change unguided (16). Retreat has often been viewed as a failure to adapt or considered only when all other options are exhausted (12,(17)(18)(19)(20)(21). But this conceptualization ignores lessons from numerous disciplines drawing on a long history of human movement and limits adaptation researchers and decision-makers in preparing for a broad range of futures.…”

Introduction: Managed retreat and environmental justice in a changing climate

“…People may move autonomously or through managed retreat (also called planned retreat, relocation, or resettlement): the purposeful, planned, and coordinated movement of people away from hazardous areas or areas of extreme environmental degradation (Hino et al 2017;Ajibade et al 2020). Managed retreat has long been recognized as a potential adaptation strategy and has been used to address floods and other hazards, but it has often been considered a last resort-an option to be pursued only where in situ adaptation or risk reduction measures are ineffective or prohibitively costly (IPCC 2007;Siders 2019;Anderson et al 2020). However, as the effects of climate change have become more apparent and more severe, there has been a growing recognition among scholars and practitioners that incremental adaptation or armoring may be insufficient in the face of future change (Kates et al 2012).…”