Assessment of climate change impacts in the North Adriatic coastal area. Part I: A multi-model chain for the definition of climate change hazard scenarios

Climate scenarios produce climate change-related information and data at a geographical scale generally not useful for coastal planners to study impacts locally. To provide a suitable characterization of climate-related hazards in the North Adriatic Sea coast, a model chain, with progressively higher resolution was developed and implemented. It includes Global and Regional Circulation Models representing atmospheric and oceanic dynamics for the global and sub-continental domains, and hydrodynamic/wave models useful to analyze physical impacts of sea-level rise and coastal erosion at a sub-national/local scale. The model chain, integrating multiple types of numerical models running at different spatial scales, provides information about spatial and temporal patterns of relevant hazard metrics (e.g., sea temperature, atmospheric pressure, wave height), usable to represent climate-induced events causing potential environmental or socio-economic damages. Furthermore, it allows the discussion of some methodological problems concerning the application of climate scenarios and their dynamical downscaling to the assessment of the impacts in coastal zones. Based on a balanced across all energy sources emission scenario, the multi-model chain applied in the North Adriatic Sea allowed to assess the change in frequency of exceedance of wave height and bottom stress critical thresholds for sediment motion in the future scenario (2070-2100) compared to the reference period 1960 to 1990. As discussed in the paper, such projections can be used to develop coastal erosion hazard scenarios, which can then be applied to risk assessment studies, providing valuable information to mainstream climate change adaptation in coastal zone management.