Climate change impact on underwater cultural heritage and historical stone materials

Climate change has an outstanding impact on seas and oceans, not only on the marine environment and ecosystems but also on underwater cultural heritage. This includes millions of submerged historical settlements, wrecks, artifacts, and structures worldwide, whose protection depends on the international mitigation and adaptation agenda. The EU-funded project WATERISKULT provides the first quantitative assessment of the climate change risk to underwater cultural heritage, with a focus on archaeological stone artifacts and structures. The research approach is characterized by a high degree of interdisciplinarity and is based on mixed field and laboratory experimentations. The key-factors of climate change addressed are ocean acidification and extreme weather events. Their impact on the conservation of historical materials is investigated by an array of laboratory simulations and underwater monitoring tests, studying the stages and rates of stone deterioration. The two main decay processes spotlighted are carbonate mineral dissolution at different pH levels in seawater, and surface erosion from the violent marine currents developing during storm events. The risk assessment is supported by the investigation of stone decay observed in selected underwater sites in the western, central, and eastern Mediterranean Sea (in France, Italy, and Cyprus); here, the link between biological, chemical, and physical deterioration and the variability of stone properties and environmental settings is explored. Following these research directions, WATERISKULT aims at enhancing the knowledge of the vulnerability of ancient materials in the underwater environment, providing the scientific basis for fine-tuning long-term policies for stone heritage protection.