Climate change could erase ancient Indonesian cave art

Credit: Basran Burhan

Griffith University-led researchhas revealedthat some of the world’s earliest known rock art is disappearing atan alarming rate. This includescave paintingsdated to at least 44,000 years ago that are believed to be the oldest survivingartisticdepictionsofhunting scenesand supernatural beings.

In a study published inScientific Reports, a team of Australian and Indonesian archaeological scientists,conservation specialists and heritage managers documentedthe mechanisms behind increasing loss ofpainted limestone cave surfaces in southern Sulawesi, Indonesia.

Staff from the BPCB conservation agency undertaking rock art monitoring in Maros-Pangkep. Credit: Rustan Lebe

Their findings indicate thatdeteriorationof these globally significant artworksisaccelerating instep withclimate change.

Thestudy revealedevidenceforsaltcrystallisation(haloclasty) on Pleistocene-aged rock artpanels at 11 limestone cave sites inMaros-Pangkep.

Study lead,Dr Jillian Huntleyfrom the GriffithCentre for Social and Cultural Research,specialisesin rock art conservation. Her research scientificallydescribes the properties of rock art and the caves or rock shelter environments where it survives today.

DrHuntley said shewas shocked by the extent of salt weathering on thepaintedlimestonecavesurfaces in Sulawesi.

“I wasgobsmackedby how prevalent the destructive salt crystals and their chemistry were on therockart panels,some of which we know to be more than 40,000 years old,she said.

Unlike the temperate climates where famous European ice age cave art sites such as Altamira andLascauxare found, the ancient Indonesian paintings are located in the tropics,the most atmosphericallydynamic region on the planet. The mid-latitudes act as the heat engine for global climate cycles, and globalwarming can be up to three times higher in the tropics as a result.

Dr Huntley said high temperatures and more consecutive dry dayswere combining with the retention of monsoonal rainsinrice fields and aquaculture ponds to provide ideal conditions for stone decay.

“Our analysesshowthathaloclastyis not only chemically weakening the cave surfaces, the growth of salt crystals behind ancientrock art is causing it toflake off the walls — it is disappearing before our eyes,shesaid.

“In myopinion, degradation of this incredible rock art is set to worsen the higher global temperatures climb.

The research collaboration was undertaken with specialists from Indonesian peak bodies, the National Research Centre for Archaeology (ARKENAS) and Makassar’s culture heritage department,BalaiPelestarianCagarBudaya(BPCB).

ARKENASdirector I. MadeGeriasaid: “The rock art ofMaros-Pangkepprovides crucial insight into the world of ancient Indonesia. Preserving this art for future generations requires the cooperation and long-term commitment of scientific research institutions, cultural heritage agencies, government authorities, and local communities. It also requires us to educate people in Indonesia – and throughout the world – about the urgent need to study and safeguard this irreplaceable evidence of past human civilization.”

AdhiAgusOktaviana, anIndonesian rock art expert withARKENASand Griffith PhD scholar,saidthetrue extent of the region’s rock art remainedunknown.

“We have recorded over 300 cave art sites inMaros-Pangkep. Our teams continue to survey the area,finding new artworks every year. Almost without exception the paintings are exfoliating and in advanced stages of decay. We are in a race against time,” he said.

RustanLebe, aBPCBarchaeologist based inMaros-Pangkep, coordinates an emerging program of rock art and microclimate monitoring in the region. According toRustan“we have recorded rapid loss of hand-sized spall flakes from these ancient art panels over a single season (less than five months)”.

“Apart from studying how the salts are forming on the cave walls, it is important to consider the analysis of rock art pigment composition and image production techniques, which could possibly provide insight into why some individual motifs exfoliate more quickly than others.”

Sulawesianarchaeologist and Griffith PhD scholarBasranBurhanwas also an integral member of the studyteam.

Credit: Linda Siagian

“Cave art discoveries are revealing more and more about how advanced the cultural lives of the first peoples living in Sulawesi were. Detailed paintings of animals, hand stencils and narrative scenes of greatantiquity show that people have been connected to this place for tens of thousands of years,” he said.

Aside from the directimpactsassociated with industrial development such asmining, altered climatestatesresulting from global warming are the biggest threat to the preservation of the ice age art of the tropics.

“The challenges of climate change adaptation for the Indonesian Maritime Continent are complex,DrHuntleysaid.

“Understanding the mechanisms of rock art weathering is even more critical in this context. Someof the solutions of looming food insecurity such as the expansion of rice fields and aquaculture ponds canhave unintended consequences. Holding surface water in these ways enhances humidity, prolonging theseasonal shrink and swell of geological salts, as well as leading to more mineral deposition. All of whichleads to rock art degradation.

“We urgently need further rock art and conservation research to have the best chance of preserving the Pleistocene cave paintings of Indonesia.”