40,000-Year-Old Rock Art Is Being Destroyed by Climate Change

The climate crisis has taken so much away from us that we’ll never get back: people, places, wildlife, even languages. Now, it’s destroying some of the oldest art on Earth, new research led by Griffith University shows.

The study focuses on ancient paintings in the limestone caves of southern Sulawesi, Indonesia. Drawn between 20,000 and 40,000 years ago, these are some of the world’s first known cave paintings.

The paintings depict people, symbols, and animals and include the earliest known drawing of an animal. But now, they’re degrading, because bits of the caves’ rock walls are flaking off. The paintings’ deterioration has been documented since the 1950s, and it’s gotten worse over that time.

To see why this is happening, the authors examined 11 different cave painting sites, using powerful microscopes and chemical analysis. They found that a large part of the problem is that salt crystals are forming on the cave’s walls, penetrating deep into them and then expanding and contracting with the air temperatures’ fluctuations. That’s making the rock weaker, causing it to crack and flake.

“In some cases, the result is the stone surface crumbling into a powder,” the authors wrote in a commentary about the study. “In other instances, salt crystals form columns under the hard outer shell of the old limestone, lifting the art panel and separating it from the rest of the rock, obliterating the art.”

The findings suggest that the effects of climate change are to blame for this. The region has also gotten hotter overall, causing the salt crystals in the caves’ walls to expand more often. The rapid oscillation between drought and heavy downpours of monsoon rains also seem to create the perfect conditions for more salt crystals to form and expand. Indonesia’s weather was already highly dynamic, but amid the climate crisis, the rapid shifts have become even more dramatic. Global warming may be driving more intense El Niños, a climate phenomenon characterized by warmer-than-normal waters in the eastern Pacific Ocean. El Niño ups the odds of drought in Indonesia as well as more heat.

As a result, the caves’ deterioration has sped up over the past four decades. And if the climate crisis gets worse, so will the paintings’ rate of decay.

Even if the world adheres to the goals of the Paris Climate Accord—which, frankly, is not a given—the Earth warming by between 1.5 to 2 degrees Celsius (2.7 to 3.6 degrees Fahrenheit) will “have grave implications for the conservation of this globally significant cultural heritage,” the study says.

The authors call for more research to look into the effects of the climate crisis on ancient treasures, and for more researchers to work to find more of these ancient art sites before they disappear. To preserve the world’s oldest paintings, they also suggest that scientists could use 3-D scanning to ensure we document them before it’s too late. And of course, we must work to curb greenhouse gas emissions to slow warming and thereby preserve what’s there while we still can.