Climate change’s heat and El Nino’s drought worsened Indonesia haze: Study

SINGAPORE – Global warming, South-east Asia’s seasonal heat and dryness, and the super El Nino weather phenomenon combined to sustain the months-long inferno in Indonesia that choked the region in thick haze in 2026.

But these events are increasingly predictable, and in turn, solvable, said a new study published on Nov 13 by the World Weather Attribution group of scientists.

“El Nino conditions – even with the extra boost from climate change – are highly predictable which provides an opportunity for proactive, preventative action to stop future years from having impacts on this scale,” said Maja Vahlberg, technical adviser at the Red Cross Red Crescent Climate Centre, which was part of the study.

Ultimately, the root cause of this year’s haze is the burning of peatlands in Indonesia that had been drained decades ago for plantation land.

There is human activity setting fires every year in Indonesia, but in El Nino years, that activity ticks up because the drought conditions are sufficient for those fires to “catch and grow really severe and get out of control”, said Theodore Keeping, extreme weather and wildfire researcher at Imperial College London, who led the study.

Still, while El Nino severely suppressed rainfall, climate change had a larger effect on amplifying heat over the region, according to the study.

The seasonal dry weather from August to October was dominated by climate change, pushing up temperatures by about 1.6 deg C.

Human-induced warming made these drier atmospheric conditions about three times more likely, and El Nino made them five times more likely to occur, according to the analysis by global weather and wildfire scientists.

“This year’s record-breaking heat would have been virtually impossible without climate change, even in a similar El Nino state,” said Keeping.

El Nino – a climate pattern associated with the unusual warming of surface waters in the eastern tropical Pacific Ocean – brings hotter and drier weather over South-east Asia.

During El Nino, warm ocean water shifts across the western Pacific and away from Indonesia, and that also pulls rainfall away from the archipelago. In 2026, the phenomenon also coincided with the traditional dry season in equatorial ASEAN, which lasted from June to October.

It thus became a triple-whammy of climatic and weather drivers that exacerbated the inferno over the region.

The current El Nino seemed to have halved the amount of rainfall between July and October. Climate change was also found to have dampened the region’s rainfall by about 15%.

World Weather Attribution is an international scientific collaboration that analyses and communicates the possible influence of climate change on extreme weather events.

Its study is one of the first to quantify climate change’s role in the Indonesia fires.

Keeping added: “El Nino was the main driver of the lack of rain this year, and then climate change pushed temperatures and atmospheric dryness into extreme territory.

“When a strong El Nino hits, global warming makes the resulting fire weather significantly hotter, drier, and harder to contain.”

Pramudhian Firdaus, a meteorologist at the Indonesian Agency for Meteorology, Climatology and Geophysics who also contributed to the study, noted that September 2026 was Indonesia’s fifth driest September since 1991, with less-than-normal rainfall across about 84% of the archipelago.

The analysis was conducted by scientists from Indonesia, the United States, the Netherlands, Sweden, and the United Kingdom, who studied the August to October fire season, which saw the highest period of fire activity.

They evaluated the meteorological conditions that contributed to the severity of the fires by analysing seasonal rainfall, temperatures, and a measure of sustained periods of hot, dry air which dries vegetation and makes it more flammable.

Indonesia’s fires, which are still burning, have razed nearly 2.9 million ha of land this year, about 18 times the size of London. The haze-belching fires turned parts of Kalimantan an apocalyptic orange in October, and led to more than 400,000 respiratory infections in Indonesia.

According to the ASEAN Specialised Meteorological Centre’s website, moderate smoke plumes were observed to emanate from a few hot spots in the eastern parts of Kalimantan on Nov 12.

The crisis also prompted school closures in Malaysia, flight disruptions and in Singapore, hospitals’ emergency departments received 20% more visits for conditions potentially related to the haze.

The researchers called for peatland restoration measures and maintaining higher water tables so that the land does not turn into a tinderbox during the dry season.

They also called for efforts to reduce deforestation and incentivise land-management practices that reduce reliance on illegal slash-and-burn activities.

On Nov 12, a report led by Greenpeace recorded over 17,800 haze-source points across 23 districts in Indonesia between August and October. Haze-source points refer to the starting points of haze identified from satellite imagery.

Of these, 2,270 were detected within 264 oil palm concessions, while another 2,938 were found within 143 pulpwood concessions.