Cave paintings on the Indonesian island of Sulawesi, believed to be the world’s oldest, are decaying at a rapid pace because of salt erosion likely caused by climate change, archaeologists warn.
The paintings in the Maros-Pangkep region include depictions of a group of therianthropes, or humans with animal characteristics, appearing to hunt animals that were found in a limestone cave in 2017 and dated to about 44,000 years ago.
Another painting of a Sulawesi warty pig was recently dated as at least 45,500 years old.
Experts are now racing against time to find ways to preserve the priceless Pleistocene artworks.
“The impact is very severe and will destroy the paintings,” Basran Burhan, an archaeologist from Australia’s Griffith University, said.
Warming temperatures and the increasing severity of El Niño events has helped speed up salt crystallisation in the cave, effectively “exfoliating” the painting, according to a study by Australian and Indonesian archaeologists published in Scientific Reports last month.
Prolonged drought combined with heavy monsoonal rainfall has created “highly favourable” conditions that have intensified the salt crystallisation, the study said.
“The pigment that makes up the image on the cave wall is peeling off,” said archaeologist Rustan Labe, pointing at images on his laptop showing the scale of exfoliation between October 2018 and March 2019.
The picture documentation showed nearly 1.5 square centimetres had peeled off within those six months.
Dr Labe, who works at the Indonesian Ministry of Education and Culture’s Cultural Heritage Conservation Centre, said archaeologists would work in small teams to monitor the growth of salt crystals and other tiny organisms on the cave wall.
“We will prevent and tackle the factors that might be a threat, and address the matter immediately,” Dr Labe said.