Unravelling the uncertainties in the climate-water-energy interplay: A distributed analysis of the Italian territory

Hydropower is a critical component of Italy's renewable energy portfolio, accounting for 45 % of the nation's renewable electricity generation. However, the future of hydropower is increasingly threatened by climate change, which may alter the availability and distribution of water resources. This study investigates the potential impacts of different climate scenarios on hydropower production across Italy's electricity market areas. We employed a methodology integrating the Representative Concentration Pathways (RCPs) from the IPCC's Fifth Assessment Report with six regional climate models, downscaled using time-varying quantile mapping. These high-resolution projections of precipitation and temperature were input into the BIGBANG hydrological model, producing spatially and temporally refined estimates of surface water availability across Italy. Subsequently, a data-driven model was used to estimate the impacts of water availability scenarios on hydropower production through the century. The results reveal marked regional disparities: Southern Italy is projected to face significant declines, with reductions in hydropower potential reaching up to 30 % under the most severe climate scenario. In contrast, Northern Italy, which hosts most the country's hydropower capacity, is expected to experience minimal changes in production, with potential slight increases under certain scenarios. Overall, national hydropower production is projected to remain relatively stable under RCPs 2.6 and 4.5, while RCP 8.5 (worst-case climate change scenario) experiences a 12 % decrease by the end of the century, with peaks of 30 % during the summer peak. This study underscores the importance of targeted adaptation strategies and the critical role of emission reductions in mitigating the long-term impacts of climate change on hydropower production.