Cave Conservation and Microclimates
Caves operate as nearly-closed microclimate systems. The temperature is constant year-round; humidity is high and stable; the atmosphere has its own CO2 balance. Visitors disrupt all three. Lascaux's mould outbreaks are the canonical warning.
Why caves are vulnerable
A cave atmosphere reflects long-term geological equilibrium. Inside, CO2 from soil percolation is balanced by outgassing; warm visitor breath introduces 10-50,000 ppm CO2 spikes that temporarily alter the speleothem equilibrium. Body heat raises local temperature by 1-3°C, encouraging mould growth on paintings or organic remains.
Lighting impact
Artificial light promotes "lampenflora" — algae, mosses and lichens growing under cave lights. Visible green or yellow patches on lit show-cave walls are the most common symptom; they consume calcium and disfigure formations.
Mitigation
Modern show caves use LED lighting (lower heat, narrower spectrum), strict visitor numbers, ventilation controls, and in some cases CO2 monitoring with capacity limits. Many caves close annually for "rest periods" to allow microclimate recovery.
Lascaux as cautionary tale
When Lascaux opened in 1948, no one anticipated how rapidly the microclimate would shift. Within 15 years, paintings 17,000 years old had been damaged irreparably. Closure in 1963 stopped the fastest damage, but mould outbreaks have continued.
Best practices for visitors
Never touch formations or paintings — skin oils chemically contaminate calcite. Don't enter caves with wet boots from muddy surfaces (mould spores). Follow tour pathways exactly — formations are often centimetres from path edge. Do not leave trash or food.
Cave bacteria research
Cave microbial communities are valuable scientific resources yielding novel antibiotics. Tourist impact contaminates them with surface bacteria; preservation of cave biology depends on restricting access to scientifically critical sites.
Explore on the map
See caves with conservation programs on the interactive map.