WWA: climate change made Indonesia's 2026 fire season 1.6 °C hotter, intensifying the El Niño drought
A World Weather Attribution rapid analysis found El Niño cut rainfall by about 50%, while record heat came mainly from human-caused warming. Fires burned 1.9 million hectares.
A rapid analysis by World Weather Attribution (WWA), a network of researchers who assess the role of climate change in extreme weather, found that human-caused warming significantly amplified heat during Indonesia's 2026 fire season, news.mongabay.com reports. mongabay.com
news.mongabay.comnews.mongabay.comOpen source ↗ The team studied western Indonesia in the dry season from August to October 2026, when fires burned about 1.9 million hectares (4.7 million acres) of peatland and rainforest.
According to the report, the resulting haze exposed 12.5 million people across Southeast Asia to hazardous air pollution and caused more than 400,000 respiratory infections in Indonesia alone.
El Niño, record heat and drought
The researchers found that a strong El Niño was the primary driver of an “extreme lack of rainfall”, cutting seasonal precipitation by roughly 50% over the three months. Record-breaking temperatures, however, were overwhelmingly driven by global warming. Human-induced climate change made the season 1.6 °C (2.9 °F) hotter, and such extreme heat would be virtually impossible without greenhouse gas emissions, the authors found.
El Niño added 0.3 °C (0.5 °F) of warming. Climate change also tripled the likelihood of weeklong hot, dry atmospheric extremes. mongabay.com
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Co-author Theodore Keeping of Imperial College London said El Niño set the conditions for very low rainfall and a major fire-season drought, which was then exacerbated by record heat made possible by human-caused climate change. Co-author Friederike Otto, also of Imperial College London, said that in many cases the effect of climate change on temperature now surpasses the effect of El Niño.
Degraded peatlands
The WWA authors said climate change compounded decades of severe landscape degradation. Between 1990 and 2010, peat swamp forest cover declined by 45% in Borneo and 63% in Sumatra because of agricultural drainage and logging. Drained, dried-out peatlands ignite easily, and fires there smolder underground for weeks, releasing large carbon reserves.
Co-author Pramudhian Firdaus, a meteorologist at the University of Melbourne and the Indonesian meteorological agency, said that extensive peatland drainage and deforestation have made Indonesian landscapes extremely vulnerable to ignition. In his words, El Niño set the stage, but the peatland is what makes the fires so severe. mongabay.com
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The WWA researchers added that protecting intact forests, restoring drained peatlands and enforcing zero-burning land clearing are essential to prevent future catastrophic haze events as global temperatures rise further.
