Decorated caves under climate change: Redefining an effective conservation strategy – DECACLIM

The common conservation strategy of decorated caves focuses on maintaining a stable underground microclimate with time. Cave paintings are generally situated at a rock/thin water film/atmosphere interface that should remain as constant as possible. The current environmental monitoring of shallow decorated caves (< 40 m) reveals (i) a general increase of underground temperatures that can be significantly accentuated (up to 2°C per decade) by a change in the cave internal aerology; (i) an increase of CO2 level in the ambient cave atmosphere that sometimes limits the access to the cave. These two processes, related to the anthropogenic climate change, destabilize the thin water film that covers cave paintings (growth by condensation that may wash out the paintings, or evaporation with formation of carbonate concretions). A supplementary risk amplified by a change in the cave internal aerology, is the rapid propagation of microorganisms that can cause huge crises in decorated caves.
Based on the detailed studies of three decorated caves with contrasted geographical settings (Gargas cave, Points cave, and Villars cave), this project aims at identifying the tipping points that may lead to an alteration (physical and/or biological) of cave paintings. It relies on (i) an innovative environmental survey in the caves (thickness of the thin water film, CO2 production in soil, drip rate measurements, identification and counting of airborne and wall microorganisms...); (ii) a combined modelling of cave microclimate and thermal/fluids transfer through the soil/epikarst/karst system, that will allow the use of meteorological parameters generated by down-scaled versions of climate change scenarios.
This project will define an innovative conservatory approach to protect intangible cultural heritage in the context of climate change (measurement instrumentation, appropriate diagnostic tools, management of surface land...).