The volunteers risking their lives to defuse Indonesia's wildfire 'carbon bombs'

In Borneo, the fire is burning beneath the ground as much as above it. Smoke steams from the soil, while an amber haze has spread across borders to Singapore, Manila and Kuala Lumpur.

For volunteer firefighter Dwi Sujatmoko, the air feels like tear gas. “It hits your nose straight away, your eyes burn, that’s more or less what it’s like,” he says. Sujatmoko, 35, has spent more than a month working through the haze, using hand tools, carts and portable pumps against fires that have already carbonised about 200,000 hectares of forest and farmland across Indonesian Borneo.

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It hits your nose straight away, your eyes burn, that’s more or less what it’s like.

Thousands of volunteers, many of them Indigenous Dayak or Banjar people, are fighting a fire front that seems impossible to extinguish. The most dangerous flames are often out of sight. Giant peat fires continue to smoulder underground, filling the air with poisonous fumes and making the blaze difficult to control.

“Once a fire becomes uncontrolled, it harms many people. Not just humans, but also animals and plants,” Sujatmoko says. “If underground fire spreads and can no longer be controlled, the losses are enormous.”

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Once a fire becomes uncontrolled, it harms many people. Not just humans, but also animals and plants.

The fires are spreading during a so-called “Super El Niño,” which has intensified drought conditions and helped drive thousands of active hotspots across Indonesia. The resulting haze crisis is described as the region’s worst in more than a decade.

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Peatlands are incredibly effective carbon stores because their waterlogged conditions slow decomposition, allowing carbon to accumulate underground for thousands of years.

Borneo’s peatlands make the disaster especially significant. The ecosystem covers 4.5 million hectares of forest and swamp and normally stores ancient carbon in waterlogged soil. When peatlands are drained or burned, that carbon can escape quickly as carbon dioxide, carbon monoxide and methane.

Dr Nisa Novita of the conservation group Yayasan Konservasi Alam Nusantara explains that peatlands store carbon for thousands of years because water slows decomposition. Once they dry out or catch fire, she says, they can become a “carbon bomb,” releasing that stored carbon into the atmosphere.

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But this also means they can become a ‘carbon bomb’ when they are drained or burned, because that carbon can be rapidly released into the atmosphere.