Extreme rainfall risk and climate change impact assessment for Edinburgh World Heritage sites

Human-induced climate change and the resulting increase in severity and frequency of extreme weather events is a significant threat to cultural heritage. Those responsible for the care, maintenance and conservation of cultural heritage urgently need user-driven, site specific climate risk assessments. A risk assessment framework is developed: the Cultural Heritage Climate Risk Assessment (CHCRA). The CHCRA employs and combines high -resolution climate models, expert elicitation, and literature to estimate the expected damage to physical cul-tural heritage buildings from extreme events. As a pilot study, the CHCRA is applied to cultural heritage buildings in the Old and New Towns Edinburgh (ONTE), Scotland, which is part of the Edinburgh World Heritage Site. The UK Met Office UKCP18 2.2 km high-resolution climate model, regridded to 5 km, is used to analyse extreme 1 -day rainfall events during 1981-2000, 2021-40 and 2061-80, driven by the RCP8.5 scenario. Simulated pre-cipitation is combined with impact information to estimate expected damage per year. Autumn and summer expected damages are much larger than that from spring and winter. Expected damage per year, as percentage of rebuild cost, for autumn increases from 0.4% (5-95% CI: 0.2-0.6%) in the baseline period to 0.9% (0.6-1.2%) in 2021-40 and 1.2% (0.8-1.7%) in 2061-80. Summer sees a trend in expected damage per year increasing from 0.2% (0.09-0.15%) in the baseline period to 0.5% (0.3-0.8%) in 2021-40 and 1.0% (0.7-1.4%) in 2061-80. Combined annual expected damage per year increases from 0.6% (0.3-1.1%) in the baseline period to 1.5% (0.8-2.3%) in 2021-40 and 2.3% (1.4-3.3%) in 2061-80. A 3-to 4-fold increase in annual expected damage to cultural buildings in the ONTE is expected towards the end of the 21st century due to human-induced climate change.