On a morning in Palangkaraya, Central Kalimantan, schoolchildren arrived at their desks wearing masks. Orangutans were being given oxygen by rescue workers. Ely Marlina, a 46-year-old teacher and volunteer firefighter, had not opened a window in weeks. "While we sleep, the whole family is just breathing in the smoke," she told reporters.

Her city sits inside a sepia haze that stretches across borders, a visible consequence of an invisible crisis building underground. Since January, at least 895,657 hectares have burned across Indonesia — a figure that is already 34 per cent worse than the same point in 2019, itself one of the most destructive fire years on record, according to data from Nusantara Atlas, an organisation that tracks fires and deforestation across Asia. The worst-affected areas span Sumatra, Kalimantan, and Papua. David Gaveau, the landscape ecologist who directs Nusantara Atlas, describes the trajectory bluntly: "It's trending far higher than 2019 or even 2023.

What that means is that this is a terrible year." Much of the destruction is rooted in a practice as old as the plantation economy itself. Land is cleared by fire — cheaply, quickly, and often illegally — to make way for oil palm, of which Indonesia is the world's largest producer. When those fires reach drained peatland, something far harder to control begins.

Peat fires burn underground for weeks, resurfacing unpredictably; adding water produces more smoke rather than extinguishing the flames.