Hazardous haze from Indonesian fires spreads across Southeast Asia
For weeks, Indonesia has struggled to contain forest and peatland fires that are blanketing parts of Borneo and Sumatra in thick, toxic haze. The smoke has forced school closures, prompted emergency declarations and drifted across borders to Malaysia, Singapore and the Philippines, reviving one of Southeast Asia’s most persistent environmental problems.
Where the fires are burning
Most of the blazes are concentrated on Borneo island, whose vast tropical rainforest is shared by Indonesia, Malaysia and Brunei, and in Sumatra. Independent estimates from the Nusantara Atlas put the total area burned in Indonesia this year at nearly 300,000 hectares.
Satellite monitoring has also raised concerns about the scale of emissions. The Copernicus Atmosphere Monitoring Service (CAMS) said smoke and fire activity have surged since late July, and senior scientist Mark Parrington said conditions are already rivaling the last major El Niño years of 2015 and 2019.
“We’re seeing already now... really extreme fire emissions comparable to those previous strong El Niño years, and also the extent of the smoke and the haze and the air quality impacts,” Parrington said.
CAMS data show that between Aug. 28 and Sept. 3, fires in Indonesia released more than 23 million metric tons of carbon. That exceeds the 20.7 million tons released during the same period in 2015, a benchmark year for choking transboundary haze in the region.
Why this season is severe
The return of El Niño has created drier conditions that allow fires to spread quickly. The United Nations said this week that the current El Niño could become the strongest in four decades. But experts stress that the climate pattern alone is not the root cause.
“El Niño does not ignite fires. It creates the dry conditions that allow human-started fires to escape and become very large,” said David Gaveau, founder of the Nusantara Atlas.
Slash-and-burn land clearing, widely used to prepare land for farming and plantations, remains a major driver. The problem is especially severe on drained peatlands, which are naturally wet ecosystems that store large amounts of carbon but turn highly flammable once their moisture is removed.
“When peat is drained, this organic material is converted into fuel,” said Wahyu Perdana, spokesman for Indonesian peatland monitoring group Pantau Gambut. The group detected more than 210,000 hotspots in peatland areas across the country between January and August this year.
Who is being hit hardest
The health consequences are already severe. Indonesia’s deputy health minister, Dante Saksono Harbuwono, said last month that more than five million people in Borneo and Sumatra are directly exposed to the haze. More than 1.4 million students have shifted to remote learning as schools close because of dangerous air quality.
Across the border in Malaysia, authorities declared an emergency in a district of Sarawak state after pollution readings spiked, and nearly 650 schools were ordered to close. In the Philippines, smoke pushed air quality into the “very unhealthy” and “severely unhealthy” ranges for days, forcing city and provincial officials to suspend classes; readings have only recently begun improving. Singapore’s central region also logged “unhealthy” air on Friday.
Indonesia has said it is coordinating with neighbors through regional haze response mechanisms. Foreign Ministry spokesman Vahd Nabyl Achmad Mulachela said Saturday that regular meetings among Association of Southeast Asian Nations members on transboundary haze and follow-up measures continue to be held.
The current outbreak has revived memories of 2015 and 2019, when fires across Sumatra and Borneo blanketed the region for weeks and triggered diplomatic friction. With El Niño tightening its grip and peatlands still vulnerable to drainage and development, the worst of the season may not be over. Regional governments are again being tested not only on how they fight fires, but on how they prevent them from starting in the first place.