An Ultrametric Composite Indicator for Ranking the Environmental Sustainability Performance of Italian Provinces

Assessing environmental sustainability is a critical challenge for policymakers, requiring robust and objective methodologies to evaluate and compare territorial performance. This study proposes the Ultrametric Composite Indicator (UCI) model as a statistically rigorous approach to ranking the environmental sustainability of Italian provinces, offering a hierarchical framework for variables aggregation. The UCI model employs a datadriven approach to integrate key sustainability measures (i.e. air quality, waste management, and soil consumption) into a structured ranking system. An exploratory analysis facilitates the identification of latent relationships among variables, organizing them within a hierarchical structure. Composite scores are then computed at each level and normalized to generate the final ranking. The results provide policymakers with an interpretable and reliable tool for monitoring sustainability trends and designing targeted interventions.