Wildfires on Indonesia's Sulawesi island threatened prehistoric cave paintings, including works described as among the world's oldest. Heat and smoke could accelerate deterioration even without flames reaching the art, while soot could build up on rock walls and obscure the images.

The fires, which have hit Sumatra and Borneo hardest, had also spread to Sulawesi. Firefighters were working to contain them. Higher temperatures and reduced rainfall linked in the reports to El Niño had left forests and peatlands particularly vulnerable.