Climate crisis hastening decline of world’s oldest cave paintings

The climate crisis is speeding up the deterioration of some of the world’s oldest cave paintings, experts say.

The paintings in Indonesia, which are up to 45,000 years old, include the oldest known hand stencil, dating from 39,900 years ago, according to a study in Scientific Reports.

Rising temperatures and more consecutive dry days, combined with standing water from monsoon rains, are increasingly creating ideal conditions for weathering caused by salt crystals, the researchers found.

The art was drawn in caves in Maros-Pangkep on the island of Sulawesi during the Pleistocene – ice age – era.

Scientists investigated 11 cave art sites to find out why the images had deteriorated, by analysing flakes of rock that had begun to detach from cave surfaces.

At three sites they found salts that form crystals on the rock surfaces, causing them to break apart.

They also found high levels of sulphur, a component of several salts, at all 11 sites.

The findings suggest the process of salt-related rock art degradation is widespread in the area.

It’s believed that alternating periods of seasonal rainfall and drought are being accelerated by rising global temperatures and El Niño events – when the sea surface in the Pacific warms every few years.

The researchers warned that continually rising temperatures had “grave implications for the conservation of this globally significant cultural heritage”.

“The equatorial tropics house some of the earliest rock art yet known, and it is weathering at an alarming rate,” they said.

“Aside from continuing limestone quarrying for the burgeoning domestic cement and marmer (marble) industries, global warming should be regarded as the greatest threat to the preservation of the ancient rock art that survives in Sulawesi and other parts of tropical Indonesia,” the report says.

Long-term monitoring and conservation efforts are needed to protect ancient rock art in tropical regions, the authors conclude.