Wildfires burning across two of Indonesia's largest island regions released a striking amount of carbon dioxide in just one week this month, drawing renewed attention to a fire pattern that recurs most years in the region.
Monitoring data showed that fires in Kalimantan, the Indonesian portion of the island of Borneo, and Sumatra produced more than 19.7 million metric tons of carbon dioxide emissions from September 1 through September 7 alone. That figure places the period among the higher weekly totals recorded for the region in recent years.
Fires in Kalimantan and Sumatra typically start during the region's dry season, when farmers and plantation operators use fire to clear land quickly and cheaply ahead of planting, a practice that becomes especially difficult to control on the peatlands that cover large parts of both islands. Peat is partially decayed organic material that can smolder underground for weeks, releasing large amounts of carbon dioxide even after surface flames are extinguished, which is part of why the region's fire seasons can produce outsized emissions relative to the visible area burned.
The smoke and haze from these fires regularly spreads beyond Indonesia's borders, affecting air quality in neighboring Malaysia and Singapore in past years, and regional governments have periodically coordinated on monitoring and firefighting support during severe seasons.
Regional air quality readings in Malaysia and Singapore over the coming weeks will show whether this year's haze spreads as widely as in past severe fire seasons.
Why are peatland fires especially significant for emissions?
Peat is decayed organic material that can smolder underground for weeks, releasing large amounts of carbon dioxide even after the surface fire appears to be out.
Does the haze affect other countries?
In past severe fire seasons, haze from Kalimantan and Sumatra has spread to neighboring Malaysia and Singapore, affecting air quality there.