Managed retreat is a strategic approach to adapting to coastal erosion and sea-level rise by relocating structures and ceasing development in high-risk areas. This policy is considered sustainable as it allows natural coastal processes to occur without human interference, thereby preserving ecosystems and reducing long-term economic costs associated with maintaining artificial defenses. By contrast, building extensive sea defenses, such as pouring thousands or millions of tons of concrete, represents an unsustainable solution. Such practices not only disrupt marine and coastal ecosystems but also entail massive financial outlays for construction and ongoing maintenance. Moreover, these defenses often protect only specific, limited areas, benefiting a small number of people while potentially exacerbating erosion and flooding problems elsewhere.
