Forest fires burning across the islands of Borneo and Sumatra have blanketed large areas of Indonesia in thick smoke, pushing toxic haze across national borders into Malaysia, Singapore, and the Philippines. Borneo is shared between Indonesia, Malaysia, and Brunei, and the cross-border smoke has created severe public health hazards across the region. In Indonesia's West Kalimantan province, disaster management authorities reported that air quality dropped to dangerous levels on Thursday, reducing visibility below one kilometre. Across the border in the Malaysian state of Sarawak, authorities declared a state of emergency in Serian district after air pollution crossed hazardous thresholds on Friday. The persistent haze has forced school closures in both Indonesia and Malaysia as hospitals report rising cases of respiratory illness. Indonesian authorities have deployed thousands of emergency workers and volunteers to combat blazes that have consumed nearly 300,000 hectares of land since the start of 2026.
Fires have also encroached on the periphery of Nusantara, the new Indonesian capital currently under construction in East Kalimantan. Roughly 400 hectares have burned around the planned city, including a primary blaze that burned 300 hectares inside a nearby forest park. In response, national authorities announced plans to accelerate helicopter water bombing and attempt cloud seeding to induce artificial rainfall. Firefighters face particular difficulties in peatland zones, where partially decomposed organic matter ignites underground and smoulders for weeks. The non-governmental organisation Pantau Gambut recorded more than 210,000 hotspots across Indonesian peatlands between January and August. David Gaveau, founder of forest monitoring organisation Nusantara Atlas, points to historical logging and land clearing as the underlying driver of the crisis.
“The cause is deforestation and forest degradation over the past 50 years.”
Data from the Copernicus Atmosphere Monitoring Service shows that Indonesian fires generated more than 23 million tonnes of carbon emissions during the seven-day period leading up to 5 September. That volume exceeds the 20.7 million tonnes recorded during a comparable peak week during the strong El Niño episode of 2015. United Nations forecasts indicate the current El Niño could be the strongest recorded in four decades, causing prolonged drought that dries out vegetation and leaves drained peat swamps vulnerable to ignition. While slash-and-burn clearing remains illegal except for traditional smallholder farmers, commercial agricultural operators, including palm oil producers, continue to face scrutiny for deliberate burning. Carbon emissions have climbed steadily since late July, matching emission patterns seen in 2015 and 2019.
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“We are already observing really extreme fire emissions, comparable to previous strong El Niño years, as well as the scale of smoke, haze and air quality impacts.”
The rapid expansion of fires has intensified threats to endangered wildlife populations endemic to Borneo and Sumatra. In the Ketapang district of West Kalimantan, the conservation organisation YIARI evacuated a female orangutan and her baby on Thursday after monitoring the pair near an agricultural plantation since July. That rescue was the second mother-infant evacuation within days, bringing the total number of orangutans evacuated from fire zones in the district to nine in less than a month. A comprehensive survey conducted between 2021 and 2023 estimated the wild orangutan population at approximately 57,000 individuals in Borneo and 11,000 in Sumatra. Rescued primates remain under veterinary care while teams continue field monitoring across surrounding forest tracts.
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Intense forest and peatland fires in Borneo and Sumatra have burned nearly 300,000 hectares, triggering school closures in Indonesia and an emergency declaration in Malaysia.
AI text based on reports by rts.ch, RTBF, Ouest France and other publishers. Published .