Fires were back in force in 2019. In June and July, they blazed in the Arctic Circle, mostly in Alaska and Siberia. Then they ravaged tropical landscapes, burning vast tracts of land in the Brazilian Amazon and in Indonesia. Elsewhere, firefighters in Sweden, California and Australia have been kept busy trying to douse damaging infernos.
Indonesia also hit international news headlines due to persistent large-scale fires. Unusually dry weather across the archipelago this year is not fully understood, but climate scientists say that the positive Indian Ocean Dipole (IOD+), not the more familiar El Niño weather system, is likely responsible, contributing to widespread burning. IOD+ is a phenomenon that occurs when warm Pacific sea surface waters shift toward the Horn of Africa, leaving the Indonesian ocean colder than usual. Cold sea surface waters generate high pressure fronts, preventing the convection of water vapor into the atmosphere, which in turn prevents cloud formation and rainfall.
The dry season in Indonesia is now ending and the rains are beginning, raising hopes that the last fires will soon be drenched and extinguished. While there has been much speculation in the news that the heavy fire season has taken a toll on the country’s remaining rainforests, until now, there was no hard evidence to support that notion. We set out to determine how much land has burned and what type of land cover has been burning. This knowledge is crucial to understanding impacts and identifying solutions.
To provide a rapid but detailed assessment of burned areas, we analyzed time-series imagery taken by the Sentinel-2 satellites between 1 January and 31 October 2019. We performed the analysis in Google Earth Engine over seven Indonesian provinces, where fires are a recurring problem: Central Kalimantan, Jambi, West Kalimantan, South Kalimantan, Jambi and South Sumatra and Papua.
How much burned?
Our satellite assessment estimated that 1.64 million hectares burned between 1 January and 31 October in seven Indonesian provinces, including 670,000 ha (41 percent) in peatlands. This finding revealed that the scale of the 2019 fires is large, commensurate with the catastrophic 2015 fires when 2.1 million hectares burned in the same provinces.
That year, a powerful El-Niño pushed warm Pacific waters along the Equator away from the western Pacific towards the coast of Peru, and Indonesia was struck by drought-induced widespread fires. These fires were catastrophic. They burned an estimated 2.6 million hectares across Indonesia, and emitted 1.2 billion tonnes of CO2 equivalent representing half of the country’s total emissions in that year. Palangkaraya, the capital of Central Kalimantan (pop. 250,000), suffered the greatest air quality impact, and daily average PM10 concentrations often reached 1,000 to 3,000 µg m-3. This was among the worst sustained air quality measurements ever recorded worldwide. The cities of Jambi, Palembang and Pekanbaru were also affected by extreme air pollution levels from peatland fires. These cities were subjected to similar levels of fire-induced toxic smoke this year too, leading to higher than usual health risks.
Visualize 2019 burned areas in Central, South and West Kalimantan provinces with Borneo Atlas. Same can be done for Papua Province with Papua Atlas
A breakdown of the area of land burned in 2019 by province and by district is illustrated in the figure and table below. The map is available interactively for four out of seven provinces on the Borneo and Papua Atlas an independent geo-platform that improves transparency and accountability of plantation companies.
|Ogan Komering Ilir-Sumatera Selatan||239,604||2|
|Kotawaringin Timur-Kalimantan Tengah||51,664||9|
|Hulu Sungai Selatan-Kalimatan Selatan||37,886||10|
|Tanjung Jabung Timur-Jambi||37,134||11|
|Musi Banyuasin-Sumatera Selatan||35,387||12|
|Barito Selatan-Kalimantan Tengah||28,934||14|
|Tanah Laut-Kalimatan Selatan||22,857||17|
|Kota Palangkaraya-Kalimantan Tengah||22,097||18|
|Kotawaringin Barat-Kalimantan Tengah||21,310||19|
Table 1. Top 20 districts with most burning
What burned ?
Based on visual inspection of high-resolution image samples (2,920 samples) taken before fire, we found that 76 percent of burning occurred on idle lands (lahan terlantar in Indonesia). Those lands were forest a few years ago, but cycles of repeated burns have converted them to unproductive degraded scrublands.