Venice and its lagoon under sea-level rise: transformative choices for a coastal socio-ecological system

Venice and its lagoon form a tightly coupled coastal socio-ecological system in which urban fabric, cultural heritage, lagoon ecosystems and regional infrastructures jointly determine vulnerability and resilience to sea-level rise. As relative sea level continues to increase due to climate change and subsidence, adaptation in Venice cannot be limited to incremental risk reduction but requires transitions between fundamentally different strategies.This contribution applies an adaptation pathways perspective to the Venice–lagoon system to examine how the available solution space decreases under rising sea level. Four adaptation strategies are considered: an open-lagoon configuration based on mobile barriers and accommodation measures, ring-diking that isolates the historic city and other settlements from the lagoon, (closed-lagoon configuration with permanent coastal barriers), and retreat through relocation or abandonment. The analysis focuses on how physical constraints, ecological impacts, social acceptability and long lead times interact to shape transitions between these strategies as sea level rise continues.The Venice case illustrates how climate and geo-processes, infrastructures, available technical solutions and cultural values condition the timing and characteristics of adaptation tipping points, beyond which strategies can no longer meet their intended goals. By explicitly linking alternative strategies to distinct socio-ecological transformations of the city and its surrounding environment, the pathways approach helps clarify trade-offs, irreversibilities and decision time windows for urban transformation under deep uncertainty.The results highlight the importance of early, anticipatory planning for coastal cities facing long-term sea-level rise, and demonstrate how geoscience-informed adaptation pathways can support governance of transformative change in complex urban regions.