Climate change may be accelerating the degradation of ancient Indonesian rock paintings, including the world’s oldest manual template, dating back 39,900 years.
Rock paintings made with red and purple pigments in the limestone caves and rock shelters of Maros-Pangkep, Indonesia, have been dated to between 20,000 and 45,000 years old. Evidence suggests that the paintings have been deteriorating at a rapid rate in recent decades, but the reasons are unclear.
The scientists investigated the possible causes of the accelerated degradation of the rock art in 11 sites of Maros-Pangkep, analyzing the rock scales that had begun to detach from the cave surfaces. They publish results in Scientific Reports.
They found salts, such as calcium sulfate and sodium chloride, in the rock flakes of three of the deposits. These salts are known to form crystals on the surface of rocks, causing them to break down.
They also found high levels of sulfur, a component of various salts, in the 11 deposits. The results may indicate that the degradation process of salt-related rock art is widespread in Maros-Pangkep.
The researchers suggest that repeated changes in temperature and humidity caused by alternating periods of seasonal rain and drought create conditions that favor the formation of salt crystals and the degradation of rock art.
For this reason, they propose that these changes may be accelerated by the increase in global temperatures and the greater frequency and severity of extreme meteorological phenomena due to climate change and El Niño phenomena. And they conclude that long-term monitoring and conservation efforts are necessary to protect ancient rock art in tropical regions.