Climate change risk assessment of built cultural heritage sites in Italy

Abstract Italy, which hosts the largest number of UNESCO World Heritage Sites, is increasingly threatened by climate change, a major driver of physical, chemical and biological deterioration in built cultural heritage worldwide. This study evaluates future climate-driven risks to Italian heritage using high-resolution (~5.5 km) projections from seven bias-corrected CMIP6 models and six material damage functions. Under SSP3-7.0 (2070–2100), national mean temperature may exceed +4.0 °C, while relative humidity declines by ~4% and precipitation drops by ~84 mm. These shifts produce a general decrease in biomass, reduced lichen richness across central and southern regions, and enhanced thermoclastism in northern regions. In contrast, salt crystallization cycles (NaCl, Na₂SO₄) decline over most areas. The Composite Prioritization Index indicates a spatial reconfiguration of risk, with impacts increasingly concentrated in northern regions. Overall, climate change reshapes heritage threats rather than reducing them, strengthening some processes while weakening others, highlighting the need for adaptive and protection strategies.