THOUGHTS
When Fire Meets Peat: Why Burning Is Not The Answer For Malaysia
By Ir Dr Azfarizal Mukhtar and Wan Mohd NurulHisam Wan Nawang
Most Malaysians have lived through at least one bad haze season. You remember because the sky went yellow before noon, and the school called to say classes were cancelled. Masks sold out at pharmacies. Elderly relatives were told to stay indoors. On the news, officials talked about hotspots across the Strait of Melaka, and somewhere a map showed fires burning in Sumatra or Kalimantan, sometimes in Johor or Pahang itself.
What most people do not know is where exactly that smoke comes from. Not from trees burning above ground, at least not primarily. Much of the worst haze comes from soil. Specifically, from peat soil that has caught fire underground and is slowly burning its way downward, sometimes for weeks on end, through deposits that took thousands of years to form.
Understanding why this happens, and why it is so difficult to stop, matters more than ever. There is growing interest in using fire deliberately as a land management tool in Malaysia, a technique called prescribed burning that is widely used in countries like the United States and Australia.
Researchers from Malaysia and the United States recently completed a study comparing soil at fire management sites in Florida with soil collected in Johor and Terengganu. What they found raises serious questions about whether that kind of fire management could ever work safely on Malaysian ground.
What prescribed fire actually is
Prescribed fire is not accidental burning. It is a planned operation, carried out under specific conditions of humidity, wind speed, and temperature, on a defined area of land.
In the United States, it is used to clear dried vegetation before it builds up into dangerous wildfire fuel. Ecologists also use it to maintain habitats that need occasional burning to stay healthy.
At Tall Timbers Research Station in Florida, fire managers have been doing this for over sixty years. The technique works there because the forests sit on mineral soil, which is the ordinary sandy or clay-based ground that most people picture when they think of soil. There is a thin layer of leaf litter on top, the fire burns through it, and then it stops. The ground beneath acts as a natural barrier. Rain can put the fire out. A gap in the vegetation, called a firebreak, can stop it from spreading sideways. The process is predictable enough that trained professionals can manage it safely.
Officers from Malaysia's Fire and Rescue Department visited Tall Timbers as part of this research collaboration. The site is impressive, and the science behind prescribed burning is genuine. But as the team spent time in the field and then compared soil samples from both countries in the laboratory, something became very clear. The ground in Florida and the ground in Malaysia are not the same thing, and that difference changes everything.
Peat is not ordinary soil
Walk across a peat swamp in Johor or Pahang and the ground feels different under your feet. Softer. Spongier. That is because you are not walking on rock and clay. You are walking on compressed plant material, accumulated layer by layer over thousands of years in waterlogged, oxygen-poor conditions where organic matter does not fully decompose. The result is a soil made almost entirely of carbon.
The research team measured carbon content in soil samples from Malaysian sites at between 49 and 56 per cent by weight. The Florida samples came in between 0.14 and 3.17 per cent. Put those numbers side by side and the scale of the difference becomes clear. Malaysian peat contains roughly 70 times more carbon than the American mineral soil where prescribed burning is safely practised.
There is another difference that matters even more from a fire safety perspective. In Florida, the carbon content drops sharply as you go deeper into the soil. At 25 centimetres down, you might measure around 3 per cent carbon. At 75 centimetres, it has fallen to roughly 1.5 per cent. Go deeper and you hit mineral substrate, which does not burn. That boundary is what limits the fire.
In the Malaysian samples, the carbon content at 25 centimetres was around 55 per cent. At 75 centimetres, it was still around 54 per cent. There was almost no difference at all. The researchers only measured to 75 centimetres, but peat deposits in Peninsular Malaysia commonly extend to three, five, sometimes 10 metres deep. The fuel load continues far below anything the sampling reached.
There is no mineral layer waiting to stop a fire. The fuel goes all the way down.
The problem with underground fire
When fire enters peat, it does not behave like an ordinary fire. It transitions into something called smouldering combustion, a slow, flameless burning process that works through the organic material using oxygen that seeps in through the tiny channels within the peat itself. No visible flame. No roar. Just heat, slowly advancing downward and outward.
This is why peat fires are so difficult to fight. You cannot see where the burning front is. Water poured on the surface does not penetrate deeply enough to cool the smouldering zone below. A firebreak stops a surface fire from spreading sideways, but the underground burning can travel beneath it. Crews have extinguished what they thought was a fire only to have smoke re-emerge days later from a different location, because the smouldering had simply moved.
A fire of this kind can burn through a rainstorm. It can last for weeks. And the carbon it releases is substantial. Based on the soil measurements from the Malaysian sites in this study, burning just one centimetre of peat across one-hectare releases around 55 tonnes of carbon into the atmosphere. Recorded peat fires in Malaysia and Indonesia have consumed between 25 centimetres and more than a metre of peat depth in a single event. The carbon released during the 1997-1998 haze crisis, when fires burned for months across Sumatra and Kalimantan, was estimated at nearly one billion tonnes.
The smoke itself is also different from ordinary fire smoke. Smouldering peat produces relatively more carbon monoxide and methane compared to a normal flame, both of which are potent greenhouse gases. It also generates very fine particulate matter, the kind that penetrates deep into the lungs and contributes to the respiratory illness spikes that Malaysian hospitals record during every serious haze event.
Open burning: a different category, the same risk
Prescribed fire and open burning are not the same thing. Prescribed burning is planned, controlled, and carried out by trained personnel following protocols designed to keep it manageable. Open burning is informal, often illegal, and almost always uncontrolled.
Under the Environmental Quality Act 1974, open burning of vegetation in Malaysia is restricted, and burning on peatland is prohibited. In practice, enforcement is uneven, particularly in rural areas where farmers have long used fire as the cheapest and fastest way to clear land between planting seasons.
The danger specific to peatland is this. A farmer might burn crop residue on the edge of a drained peat area and extinguish the surface fire before going home. But if the burning reached the peat below the surface, the fire did not stop when the flames went out. It continued underground. Days later, smoke emerges from a location no one was watching, and the fire has now established itself in the soil. At that point, no amount of water poured on the surface will reliably put it out.
Drained peat is particularly vulnerable. When drainage canals are dug through peatland for agriculture or plantation use, they lower the water table. The peat that was once saturated becomes dry enough to catch fire. Research has estimated that drained peatlands across Southeast Asia already release around 500 million tonnes of carbon every year just through slow decomposition, before any fire is considered. A fire event on top of that decomposition loss is the difference between a manageable problem and a regional crisis.
So, what should be done?
The straightforward answer from the science is: keep peat wet. Saturated peat cannot smoulder. If the water table stays high enough, ignition is prevented. This is not a complicated principle. The difficulty lies in applying it across large areas of land that have already been drained.
Peatland rewetting involves blocking drainage canals with structures that raise the local water table. It is not cheap, and it takes time to work. But studies have shown that rewetting drained peatlands can reduce carbon emissions from those areas by 40 to 90 per cent, and the fire risk falls along with the emissions because wet peat simply will not ignite.
Malaysia has made policy commitments in this direction. The ASEAN Peatland Management Strategy, to which Malaysia is a signatory, commits member countries to avoiding burning on peatlands and promotes rewetting as the primary restoration tool. The gap between policy and implementation on the ground remains the practical challenge.
Satellite monitoring has improved significantly in recent years. Systems like NASA's MODIS fire detection programme track active fires across Southeast Asia daily, and Malaysian authorities now receive near-real-time alerts when hotspots appear. Faster detection means faster response, though once a peat fire is established underground, response options remain limited.
Community awareness matters enormously. People who live near peatlands often notice the early signs of fire before any satellite does. They smell smoke when there is no visible flame. They see the ground steaming in the early morning. Channels for reporting those observations quickly, and confidence that the report will be acted on, are part of what determines whether a small underground fire becomes a large one.
A carbon store we cannot replace
The peat that lies beneath large parts of lowland Malaysia is not an obstacle to development. It is a carbon archive that took thousands of years to form. Once burned, it is gone.
The researchers involved in this study came to understand that difference not through numbers alone but through fieldwork. Standing in a Florida pine forest watching a low fire move through the understorey and then quietly die at the edge of a firebreak, it is possible to see why prescribed burning has a legitimate place in land management.
Standing at the edge of a Malaysian peat swamp, knowing what lies below, you understand equally clearly that the two places are not the same. What works in one does not transfer to the other.
The haze that periodically disrupts life across Malaysia and its neighbours is not inevitable. It has causes, and those causes are connected to decisions about how peatland is drained, managed, and whether fire is used near it. The research being done by teams from Malaysian universities, fire agencies, and international partners aims to give decision-makers better information for those choices.
For now, the clearest message from the soil samples is also the simplest one. Malaysian peat is not American mineral soil. The fire management techniques developed for one cannot be borrowed for the other. And the most effective thing that can be done to protect peatland, the communities near it, and the regional air quality that everyone depends on, is to keep water in the ground and keep fire away from it entirely.
-- BERNAMA
Ir Dr Azfarizal Mukhtar is a Senior Lecturer at Universiti Tenaga Nasional (UNITEN) while Wan Mohd NurulHisam Wan Nawang is a Senior Fire Superintendent II at the Fire and Rescue Department of Malaysia (FRDM).
