Climate Change and Its Potential Impact on the Conservation of Wooden Pile Dwellings in Lake Bolsena: Insights from Climate Proxy Data and High-Frequency Water Monitoring

This study examines the impact of recent climatic trends on the preservation of submerged wooden structures at the Gran Carro archaeological site in Lake Bolsena, Italy. Climatic data from the Bolsena Meteorological Station were analysed alongside in situ water quality measurements collected at a depth of 4 meters near the archaeological remains. Key parameters included water temperature (Tw), redox potential (Eh), dissolved oxygen (DO), and total dissolved solids (TDS). Over the past decade, there has been an increase in days with air temperatures exceeding 30 °C and a general rise in mean temperatures. In 2022 and 2023, elevated air temperatures correlated with increased water temperatures, decreased redox potential, and reduced dissolved oxygen levels. Additionally, high evapotranspiration rates and declining water levels, as confirmed by UAV analyses, suggest intensified stress on the lake ecosystem, particularly due to increased water extraction for irrigation. These conditions may have created an environment with heightened anaerobicity, favouring the activity of erosion bacteria known to degrade submerged wood. Conversely, higher evapotranspiration rates could facilitate oxygen penetration to lower depths, potentially reactivating decay agents such as soft rot fungi and tunnelling bacteria. Overall, these climatic changes appear to have a detrimental effect on the preservation of submerged wooden structures in the lake. Consequently, adaptive management strategies will be necessary to mitigate these impacts and ensure the protection of both the lake environment and the archaeological wooden remains.