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Abstract Given the inevitability of sea-level rise, investigating processes of human-altered coastlines at the intermediate timescales of years to decades can sometimes feel like an exercise in futility. Returning to the big picture and long view of feedbacks, emergent dynamics, and wider context, here we offer 10 existential questions for research into human–coastal coupled systems. 

Abstract The discussion of adaptation to climate change in coastal areas has focused on short-term risk reduction and climate-proofing, but there is growing recognition that—at some point in the future—relocation to less vulnerable geographical areas will become necessary for large numbers of residents in many coastal communities. Spontaneous relocations that occur after catastrophic events can entail high costs, both for those who resettle elsewhere and for the remaining community. Managed retreat attempts to reduce such costs, thereby facilitating the relocation process. Property buyouts, the most prominently discussed policy tool for managed retreat, present significant challenges in terms of equity, timing, finance, and scale. We discuss innovation in buyout policy that allows residents to remain in their homes as renters after being bought out. We develop the basic structure of such a policy and show the pathways through which it can help to finance buyouts, harmonize public and private decision-making, and manage the timing of community transition. We also recommend funding mechanisms and other details to overcome the substantial barriers to implementation. Although buyouts with rentbacks will require institutional innovation in order to serve as an effective policy framework, the policy has the potential to improve social, economic, and environmental outcomes from the eventual unfortunate but necessary migration away from coastal areas. 

Abstract Empirical diagnosis of stability has received considerable attention, often focused on variance metrics for early warning signals of abrupt system change or delicate techniques measuring Lyapunov spectra. The theoretical foundation for the popular early warning signal approach has been limited to relatively simple system changes such as bifurcating fixed points where variability is extrinsic to the steady state. We offer a novel measurement of stability that applies in wide ranging systems that contain variability in both internal steady state dynamics and in response to external perturbations. Utilizing connections between stability, dissipation, and phase space flow, we show that stability correlates with temporal asymmetry in a measure of phase space flow contraction. Our method is general as it reveals stability variation independent of assumptions about the nature of system variability or attractor shape. After showing efficacy in a variety of model systems, we apply our technique for measuring stability to monthly returns of the S&P 500 index in the time periods surrounding the global stock market crash of October 1987. Market stability is shown to be higher in the several years preceding and subsequent to the 1987 market crash. We anticipate our technique will have wide applicability in climate, ecological, financial, and social systems where stability is a pressing concern.