This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Forest and land fires across Indonesia have spiked once again. News and social media in the country are flooded with images of thick plumes of smoke from Kalimantan (or Borneo)—the world's third-largest island—that are choking residential areas and even drifting into neighboring countries.
It is tempting to write this off as a purely weather-driven crisis: The dry season is well underway, and a strengthening El Niño is driving temperatures toward predicted historic highs around the globe. While these conditions undoubtedly amplify the risk, the crucial question isn't just why El Niño's impact is so severe—it is why parts of the landscape have become so flammable in the first place. Unsurprisingly, human activities play a major role.
Fires don't start in a vacuum. Major infernos happen when dry weather meets a Bornean landscape that has lost its natural capacity to retain water because of the expansion of industrial plantations such as pulpwood and oil palm—a loss that has been nearly irreversible for decades. Our analysis draws on data from NASA's Fire Information for Resource Management System (FIRMS), a satellite-based monitoring system providing near-real-time fire activity data.
To track how fire activity has evolved, we analyzed detection data from two satellite instruments with different spatial resolutions: MODIS (approximately 1-kilometer resolution) and VIIRS (375-meter resolution). Analysis across Kalimantan's five provinces reveals a sharp uptick in fire activity leading into mid-August. On Aug. 18, 2026, MODIS via FIRMS detected roughly 5,206 thermal anomaly pixels across Kalimantan.
At a resolution of roughly 1 kilometer, the total observation pixel area is 520,600 hectares—though this figure does not reflect the actual burned area. Meanwhile, VIIRS data shows that West Kalimantan recorded the highest cumulative detections, with 82,728 active pixels at nominal-to-high confidence levels from Aug. 1–18, 2026. Central Kalimantan followed with 34,105 pixels, East Kalimantan with 20,686, South Kalimantan with 16,602 and North Kalimantan with 5,157.
Given the 375-meter resolution of the VIIRS sensor, these detections collectively cover a total pixel area of roughly 2.24 million hectares. It is important to note that this figure does not mean 2.24 million hectares of burned area (burn scar). That figure simply multiplies the total number of detected pixels by the area of a single pixel.
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