Indonesia’s tropical peatland fires are among the most dangerous and persistent wildfires on Earth. Instead of spreading rapidly through trees and vegetation, peat fires can smolder underground through dried peat soils and massive carbon-rich deposits. Burning at relatively low temperatures, these fires are difficult to extinguish and can release hazardous air pollution for weeks or even months.
According to published research, peat fires produce about three times more particulate matter than other tropical forest fires. They also release approximately five times more sulfur dioxide, three times more organic carbon, and twice as much methane and carbon monoxide.
Satellite images reveal Indonesia’s 2026 fire season
Indonesia’s 2026 fire season was already underway when the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument aboard NASA’s Aqua satellite captured images of the region on September 1, 2026.
In this annotated satellite map, each red dot represents a fire detection. Satellite sensors and computer algorithms identify these locations as pixels containing thermal anomalies associated with active fires. A single fire can generate multiple detections.
Peat fires are a long-standing environmental threat in Indonesia, which contains approximately 36% of the world’s tropical peatlands. During severe droughts, normally waterlogged landscapes can dry out enough to ignite. Over the past three decades, these conditions have repeatedly triggered long-lasting fires that blanketed large areas in toxic smoke and disrupted the lives of millions of people.
El Niño intensifies Indonesia’s dry season
Wildfires occur in Indonesia every year, but the most destructive fire seasons in recent decades have coincided with El Niño, particularly in 1997 and 2015.
NOAA has assessed that El Niño is currently present and could strengthen during August 2026. This climate pattern typically reduces rainfall across Indonesia. Dry conditions could become even more severe if El Niño develops alongside the Indian Ocean Dipole, which is also active.
A researcher at Columbia University uses the World Fire Weather Database to generate experimental, near-real-time fire weather forecasts.
“A strong El Niño is causing drier dry seasons and worsening fires in fire-prone areas of the country, just as we expected,” he said.
Comparisons with the 2015 disaster highlight the potential scale of Indonesia’s 2026 fires. Indonesia’s wildfires in 2015 released an estimated 1.75 billion tons of greenhouse gases after burning for more than three months—more than Japan emits in an entire year. By September 2, 2026, the current fire season had continued for about a month and had already released an estimated 10% of the emissions produced during the 2015 crisis.
Underground peat fires can burn for months
Indonesia experienced severe and widespread drought during the summer of 2026, similar to conditions in 2015. Data from the Indonesian Meteorological Department showed that approximately 90% of the country received little or no rainfall in early August.
Under normal conditions, peat deposits in Kalimantan, Sumatra, and Papua are too wet to sustain underground fires. Drought can dramatically alter that situation, allowing flames to penetrate the peat and continue smoldering beneath the surface.
“Surface fires are less of a concern, but once they move underground, they can be extremely difficult to stop,” Field said. “They will continue to burn until substantial rain arrives, potentially in October or November.”
Indonesia uses NASA and NOAA satellite observations to monitor active fires in near real time. MODIS and VIIRS are among the primary instruments used for this work. Operated by Indonesia’s Ministry of Forestry, the SiPongi fire monitoring platform uses MODIS and VIIRS data and recorded 946 hotspots on August 31, 2026.
The most intense peat fires can be hardest to detect from space
Satellite monitoring has important limitations. MODIS and VIIRS can struggle to detect fires concealed by thick smoke or clouds, burning beneath forest canopies, or smoldering deep inside peat deposits.
In fact, the number of fires detected by MODIS and VIIRS can decline when Indonesia’s fires become especially intense because dense smoke blocks the satellites’ view of the ground.
“Paradoxically, the worst smoke events are the most difficult to observe from space using MODIS and VIIRS,” said Mark Cochrane, an ecologist at the University of Maryland Center for Environmental Science who has conducted field research on Indonesian peat fires for nearly a decade.
Some of Indonesia’s vulnerability to peat fires can be traced back decades. According to Cochrane, large-scale irrigation canal construction and peat-swamp drainage during the 1990s lowered water tables across the region. The failed mega-rice project left many wetlands drier and more flammable. Oil palm plantations and other forms of plantation forestry have also expanded across parts of the region.
Following the unusually severe 2015 fire season, governments and other organizations began efforts to restore damaged peatlands and reduce fire risk. These measures include blocking drainage canals to raise water tables, strengthening firefighting capacity, and expanding programs to prevent accidental and human-caused fires.
Indonesia’s 2026 fire season could test prevention efforts
“This year will be a real stress test of the measures put in place since 2015,” said Shi Jun Wee, a graduate student at the University of Maryland.
Wee is part of a team working with NASA and MapBiomas to improve the detection of subsurface peat fires that MODIS and VIIRS may miss. The team’s approach uses shortwave-infrared observations from Landsat and Sentinel-2 satellites.
As the 2026 fire season continues, Wee plans to use several NASA and global fire-monitoring resources to track conditions, including the Worldview data browser, FIRMS (Fire Information for Resource Management System), HLS (Harmonized Landsat and Sentinel-2) observations, and GFED (Global Fire Emissions Database).
Toxic smoke is disrupting daily life
The effects of Indonesia’s peat fires are already being felt by communities across Indonesia and in neighboring countries. Indonesian authorities have warned that large portions of the population are being exposed to hazardous smoke.
News reports indicated that some schools had switched to remote learning, nine national parks had closed, and several flights had been delayed because of heavy smoke and poor visibility.
Cochrane warned that peat fires often receive intense public attention during major El Niño seasons, only to fade from view when weather conditions improve.
“During El Niño events, people tend to focus on these fires and then forget about them,” Cochrane said. “Solving this problem requires continued attention, even during less severe years. These fires produce a tremendous amount of exhaust gas.”
Source: www.sciencedaily.com