Imagine a fire you cannot see, cannot easily reach, and cannot simply douse with water. It smolders beneath your feet, consuming the ground itself, and it can keep burning through monsoon rains for months on end. This is a peat fire, and it represents one of the most stubborn and carbon-intensive natural disasters on Earth.
What Exactly Is Peat?
Peat is partially decomposed organic matter, mostly dead plant material, that has accumulated in waterlogged, oxygen-poor conditions over thousands of years. Without sufficient oxygen, the normal process of decay slows almost to a halt. Instead of breaking down fully, the dead moss, reeds, and other vegetation compress into a dense, spongy material that can build up to depths of several meters.
Peatlands cover roughly three percent of Earth’s land surface, but they store a disproportionate amount of carbon. UNEP estimates that peatlands hold roughly twice as much carbon as the biomass of all the world’s forests combined, much of it accumulated since the last ice age. Tropical peatlands, particularly those in Southeast Asia, are also vast carbon stores despite covering a smaller total area.
The key to peat’s flammability lies in exactly what makes it so carbon-rich. It is, in essence, a slow-motion form of fossil fuel: dense, dried-out organic carbon waiting for an ignition source. When peatlands are drained for agriculture or timber, the water table drops and the upper layers dry out. At that point, a spark from a land-clearing fire or a lightning strike can ignite it.
Why Peat Fires Are Nearly Impossible to Extinguish
A surface wildfire burns through available fuel and moves on. A peat fire burns downward and laterally through the soil itself, with no clear front to fight and no obvious boundary to contain. Firefighters working a peat fire face a fundamental problem: the combustion is happening underground, sometimes a meter or more below the surface, where water poured on top cannot reliably reach it.
The fires also persist through weather that would extinguish almost any surface blaze. A heavy rainstorm wets the top layer of soil but may not penetrate deeply enough to reach the burning peat. Some peat fires have been documented burning for months or years, and in boreal and Arctic regions some fires smolder through the winter and re-emerge in spring as so-called “zombie fires.”
Indonesia provides the starkest illustration of the consequences. The country contains some of the world’s most extensive tropical peatlands, and drainage for palm oil and pulpwood plantations has left large areas vulnerable to fire. In 2015, an exceptionally strong El Niño event combined with widespread drainage to produce a catastrophic fire season. Estimates from researchers at the time suggested that the fires emitted greenhouse gases at a daily rate that, on many days in autumn 2015, exceeded the average daily emissions of the entire US economy, though precise figures varied across studies. The smoke blanketed parts of Southeast Asia, causing serious public health crises across multiple countries.
The Climate Feedback Nobody Wants
Peat fires matter beyond their immediate destruction because they create a troubling feedback loop. As the climate warms, droughts become more frequent and severe in many peat-rich regions. Drier conditions make peatlands more fire-prone. When they burn, they release carbon dioxide and methane that had been locked away for millennia, accelerating the warming that made the fires more likely in the first place.
Permafrost peatlands in Siberia, Canada, and Alaska add another layer of concern. As permafrost thaws, previously frozen peat can dry out and become combustible. Scientists have documented a rise in high-latitude peat fires in recent decades, and research suggests these fires are releasing carbon from deposits that had been frozen for thousands of years.
Restoring peatlands, primarily by rewetting drained areas, is considered by many researchers to be among the more cost-effective strategies for reducing emissions. Several national and international efforts to protect and restore peatlands have been announced in recent years, though the scale of implementation has generally lagged behind the scale of the problem.
Peat fires are, in many ways, a slow-motion climate emergency hiding just below the surface. Understanding what they are is the first step toward taking them seriously enough to act.