Indonesia's fires worsened by climate change and El Niño, study finds

An international scientific analysis published on Thursday found that human-caused global heating and a strong El Niño combined to make Indonesia's fire season the most severe in at least a decade, as nearly 3 million hectares burned and smoke spread across Southeast Asia.

The study by World Weather Attribution, a collaboration of scientists who assess how climate change shapes extreme weather, examined conditions in Java, Kalimantan and Sumatra during the August-to-October peak of the season. Researchers from Indonesia, the United States, the Netherlands, Sweden and the United Kingdom took part, The Independent reported.

Global heating raised temperatures over those three months by about 1.6C, drying land and vegetation, the authors found. El Niño, the natural warming of the tropical Pacific that disrupts weather worldwide, added about 0.3C and cut rainfall by roughly 50 per cent.

"El Niño turned off the taps, but fossil fuel emissions turned up the heat," said Friederike Otto, professor of climate science at Imperial College London and an author of the study, in comments carried by The Guardian and The Independent.

The Guardian reported the researchers found hot, dry air conditions were made three times more likely by climate change and five times more likely by El Niño. The Independent reported El Niño made the season's heat about 11 times more likely, and that the authors called their estimates conservative. The Independent also said the models did not reproduce the study's estimate that climate change cut rainfall by about 15 per cent, and the authors described that role as uncertain.

Land use contributed. Peat swamp forest cover fell by about 45 per cent in Borneo and 63 per cent in Sumatra between 1990 and 2010, and a further 1.4 million hectares of forest on peatlands was lost nationwide between 2009 and 2019, according to the study. Drained peat can burn underground and is exceptionally hard to extinguish.

Nusantara Atlas, a deforestation monitoring group that analyses satellite imagery, put the burned area at about 2.88 million hectares by the end of October, The Independent reported, above the 2.6 million hectares recorded in 2015. Fires are still burning because El Niño has delayed the rainy season by 20 to 30 days, according to Indonesia's Meteorology, Climatology and Geophysics Agency.

Indonesia's health ministry has reported more than 400,000 respiratory infections linked to the smoke, including about 180,000 in children aged nine and under. Haze reached Singapore, Malaysia and the Philippines, and protesters in Jakarta have called on the government to declare the fires a national emergency.

At the COP31 climate talks, Indonesia's special envoy to the president on climate and energy, Hashim Djojohadikusumo, said Jakarta would not trade development for climate action. "We will not choose between development and climate action," Anadolu Agency quoted him saying.