Indonesia Fires Become World's Largest Source of Wildfire Emissions as Pontianak Air Quality Hits 483

Indonesia's annual dry-season fires have returned with unusual force in 2026, driven by a super El Nino that has dried out forests and carbon-rich peatlands across Borneo and Sumatra. For months, crews have battled blazes in Kalimantan and eastern Sumatra, where smouldering peat can burn metres below the surface and reignite long after flames are extinguished. The result has been a blanket of toxic haze over parts of Indonesia, Malaysia, Singapore and the Philippines, forcing school closures, flight delays and the cancellation of outdoor events. Health authorities have urged residents to stay indoors, use N95 masks and seek care for breathing difficulties.

The scale of the crisis became clearer in early September, when satellite monitoring showed that Indonesian fires had become the world's largest single source of wildfire carbon dioxide emissions. Fire Emissions Watch, a portal developed by the European Union's Copernicus climate monitoring service, reported that emissions from September 1 to September 7 reached 19.7 million metric tons. That figure overtook Russia and represented more than a third of the global total for the week. Fire emission intensity exceeded 1,500 kilograms per square kilometre, more than 10 times the Russian level, with the highest concentrations in Kalimantan in Indonesian Borneo and eastern Sumatra.

At the same time, air quality in West Kalimantan collapsed. Pontianak, the provincial capital, recorded an air quality index of 483 on September 13, according to Swiss monitoring firm IQAir, a level far above the 300 threshold that the World Health Organization considers hazardous. Earlier in the month, monitors in the city had registered readings above 900. Visibility fell below one kilometre, and at times as low as 200 to 500 metres, according to Indonesia's meteorological service. The government has responded with cloud-seeding, helicopter water-bombing and law enforcement, but officials warn that the fire season is far from over.

Key Facts

Reuters reported on September 9 that fire emissions from Indonesia from September 1 to September 7 reached 19.7 million metric tons, overtaking Russia and making up more than a third of the global total, according to Fire Emissions Watch. Emission intensity exceeded 1,500 kilograms per square kilometre, more than 10 times the Russian level, and emissions were 273 per cent higher than the seasonal average. Pontianak's air quality index was 394 on September 9. A reading of 300 is considered hazardous. Recorded hotspots from August 1 to September 8 reached 13,443, versus 9,454 in the same 2015 period, according to the forest ministry's Sipongi platform using NASA satellite data.

ABC News reported on September 7 that a super El Nino had exacerbated drought and fire conditions, with at least 200,000 hectares burned, nearly three times the size of Singapore, a figure that did not yet include August. While the ABC was in Pontianak, an air quality monitor recorded a reading of more than 900. Forestry Minister Raja Juli Antoni said the field of struggle was right there in September. Malaysia declared a state of emergency in Sarawak and reported that asthma cases surged 259 per cent in the last week of August. The ASEAN Specialised Meteorological Centre activated its level 3 alert, the highest trans-boundary haze warning, for southern South-East Asia.

CNBC Indonesia reported on September 13 that BMKG issued an urgent public advisory urging citizens and local authorities to heighten vigilance against forest and land fires, focusing on West Kalimantan and Central Kalimantan as the current epicentres. Pontianak recorded the worst air quality, with an AQI+ of 483 at 09:13 WIB, the highest of any area. Other readings in West Kalimantan included Terentang at 420, Mempawah at 214, Sintang at 191, Manismata at 173 and Bengkayang at 154. Sambas Regency was the only district with relatively cleaner air at 80, still moderate. BMKG said conditions were driven by a very strong El Nino phase, a positive Indian Ocean Dipole index and the peak of the dry season.

Reuters reported on September 10 that Indonesia's health ministry said cases of acute respiratory infections linked to smoke from the fires roughly doubled within a week. The fires, concentrated in Kalimantan on Borneo and in eastern Sumatra, blanketed parts of Indonesia, Malaysia, Singapore and the Philippines in toxic haze. Health authorities warned that children, the elderly and people with pre-existing heart and lung conditions are most at risk from PM2.5 particulates. From January to July, fires burned around 202,000 hectares, about a third of the 2015 total, said Nisa Novita of the environmental group YKAN. August data are estimated to show an increase of around 600,000 hectares. In West Kalimantan, high-concentration hotspots stood at 223 as of September 11, with peat fires smouldering and reigniting underground.

Analysis

What this really means is that Indonesia's 2026 fire season is not merely a repeat of past crises but a compounding of them. The combination of a very strong El Nino, a positive Indian Ocean Dipole and the peak of the dry season has created a tinderbox environment. Mark Parrington, a senior scientist at the Copernicus Atmosphere Monitoring Service in Bonn, said that while fires are expected across the region at this time of year, El Nino clearly gives a big enhancement. It is much drier, it is hotter, and when there is ignition, these fires burn in a far more extreme way. That meteorological setup has turned what might have been a manageable fire season into one that has already produced the world's highest wildfire emissions for a week in September.

The emissions figures are striking not only because of their absolute size but because they are likely an underestimate. Parrington warned that peat fires burning underground may sit below the detection limit of the sensors, meaning the true toll could be higher. Peatlands store vast amounts of carbon, and when they burn, they release it far more intensely than surface vegetation fires. This is why Indonesia's fire emissions can spike so dramatically even when the visible burned area seems modest compared with the 2015 season. The 202,000 hectares burned from January to July was about a third of the 2015 total, but the estimated 600,000 hectares in August alone shows how quickly the picture can change.

The health consequences are already severe, and the global climate implications are significant. Reuters reported on September 10 that respiratory infections doubled in a week, and the 2015 season, which the current one could match or exceed, was linked to more than 100,000 excess deaths. The bigger picture here is that Indonesia's peatland fires are a global climate issue, not just a regional haze problem. The 19.7 million metric tons of carbon dioxide emitted in just one week is a significant addition to the atmosphere. When emissions are 273 per cent above the seasonal average, and when the fire season is still young, the annual total could be substantial. Copernicus scientists have warned that the season could match or exceed 2015.

Why It Matters

For the people living in Kalimantan and Sumatra, the fires are an immediate health emergency. Tens of thousands of respiratory infection cases have been recorded, according to Indonesia's Health Ministry, and the haze has disrupted schools, flights and daily life. Children, the elderly and those with pre-existing conditions are most vulnerable to PM2.5 particulates. The economic costs are also mounting, from lost productivity to the expense of firefighting and cloud-seeding. Malaysia's declaration of a state of emergency in Sarawak and the 259 per cent surge in asthma cases there show how quickly the crisis crosses borders.

The regional dimension is why the ASEAN Specialised Meteorological Centre activated its highest trans-boundary haze warning. Singapore and the Philippines have also been affected. This is a reminder that environmental disasters do not respect national boundaries, and that the response must be coordinated. The 2015 fires led to more than 100,000 excess deaths, and the current season has the potential to be similarly deadly if the haze continues at hazardous levels. The fact that Pontianak recorded an AQI of 483 on September 13, and had readings above 900 earlier in the month, shows that the situation remains acute. Globally, the carbon released by burning peatlands contributes to further warming, creating a feedback loop that makes future fire seasons more extreme.

Next Up

BMKG has warned that the potential for forest and land fires remains high and could continue through September to October 2026. The agency says it is executing Weather Modification Operations in close coordination with stakeholders to support firefighting and suppression. Dry conditions are expected to persist, and Copernicus scientists say emissions could keep climbing. The government is also investigating suspected deliberate land-clearing, with 72 people arrested in August on suspicion of starting fires. Monitoring will be critical: NASA's Terra and Aqua satellites, the forest ministry's Sipongi platform, and the Copernicus Atmosphere Monitoring Service are all tracking hotspots and emissions. The coming weeks will determine whether this season matches or exceeds 2015 in terms of emissions, health impacts and regional disruption.