El Niño and Wildfire Risk: A Global Connection
Published: May 19, 2026 · 9 min read
Fire and the ENSO Engine
Wildfires require three ingredients: fuel, ignition, and weather that promotes burning. El Niño influences all three on a global scale. By suppressing rainfall and raising temperatures across entire continents — sometimes for months or years — it dries out vegetation, lowers fuel moisture content, and turns forests, savannas, and peatlands into tinderboxes. The link between El Niño and wildfire is one of the clearest and most destructive patterns in the ENSO science literature.
Satellite data from NASA confirms that global burned area during strong El Niño years is consistently elevated above baseline. The mechanism is straightforward: drought desiccates live and dead vegetation, making it more flammable; higher temperatures increase evapotranspiration, compounding the drying effect; and in many El Niño-affected regions, the dry season lengthens, giving fires a wider window to spread. When combined with human land-use practices like agricultural clearing, the result is catastrophic fire seasons that release billions of tons of carbon, destroy ecosystems, and cause severe public health damage.
The Fire-Weather Mechanism
El Niño creates wildfire conditions differently across regions, but several common physical mechanisms are at work:
- Precipitation deficit: The primary driver. Months of below-normal rainfall dry surface fuels (leaf litter, grass, dead wood) and then deeper soil layers, stressing live vegetation and reducing its moisture content.
- Temperature amplification: El Niño years are warmer than average across most land areas because reduced cloud cover allows more solar radiation to reach the surface and because warmer ocean temperatures warm adjacent landmasses.
- Vapor pressure deficit (VPD): This measure of atmospheric thirst rises sharply during El Niño droughts. High VPD pulls moisture out of plants and soils faster, creating what fire scientists call "flash drought" conditions that can turn a landscape flammable in weeks.
- Dry season extension: In the Amazon, Indonesia, and Central America, El Niño delays the onset of the wet season, stretching the window in which fires can ignite and spread.
Indonesia: The 1997-98 Peat Fire Catastrophe
The 1997-1998 El Niño produced the worst fire season in recorded history across Indonesia and Borneo. An estimated 8 to 10 million hectares of land burned — an area roughly the size of Portugal. The fires were not confined to surface vegetation. They burned deep into carbon-rich peat deposits that had accumulated over thousands of years, releasing an estimated 0.81 to 2.57 gigatons of carbon into the atmosphere. To put that in perspective, the Indonesian peat fires alone released the equivalent of 13 to 40 percent of global fossil fuel emissions in that year.
The public health toll was staggering. A dense haze of smoke and fine particulate matter (PM2.5) blanketed Singapore, Malaysia, Brunei, and southern Thailand for weeks. Air pollution indices exceeded 800 in parts of Borneo — a level classified as hazardous at any duration. An estimated 20 to 30 million people were exposed to severe air pollution. The United Nations Environment Programme later estimated that the haze contributed to 40,000 to 50,000 premature deaths across Southeast Asia through respiratory and cardiovascular complications.
The fires were not a natural phenomenon alone. They were ignited deliberately by plantation companies and smallholder farmers clearing land for oil palm and pulpwood. But the El Niño drought was the enabling condition — in a normal rainfall year, the fires would have been extinguished by monsoon rains within days. During the 1997 drought, there was no rain to stop them.
The Amazon Rainforest: El Niño and Fire Feedback
The Amazon rainforest is not naturally fire-prone. Its humid tropical climate normally keeps vegetation too moist to burn. But during El Niño events, the eastern and southern Amazon — particularly the states of Para, Mato Grosso, and Amazonas in Brazil — experience intense dry seasons that strip the forest of moisture. The 2015-2016 El Niño was associated with a severe drought across the Amazon basin. Rainfall in the central Amazon was 50 to 75 percent below normal. The drought, combined with anomalously high temperatures, triggered widespread forest fires in a region that had not seen significant fire in centuries.
The 2015 El Niño Amazon fire season produced an estimated 1.6 to 3.0 gigatons of CO2 emissions. Satellite imagery showed fire scars extending deep into previously undisturbed forest. The fires created a dangerous feedback loop: burned forests are more vulnerable to future burning because they receive less shade, and the loss of tree cover reduces evapotranspiration, which in turn reduces regional rainfall, reinforcing the drying trend. This "savannization" feedback is one of the most concerning long-term risks for the Amazon under a changing climate with more frequent extreme El Niño events.
Australia: Bushfire Risk Amplified
Eastern Australia is one of the regions most consistently affected by El Niño-driven drought, and the bushfire risk that follows is well documented. During strong El Niño events, spring and summer rainfall across Queensland, New South Wales, and Victoria typically falls well below average, drying out eucalypt forests and grasslands that are already among the most flammable ecosystems on Earth. The 2019-2020 "Black Summer" fire season, while occurring during a weak El Niño phase that did not fully develop, demonstrated what happens when extreme drought and heat converge. Strong El Niño events have historically produced severe fire seasons in Australia, including 1982-83 (the Ash Wednesday fires), 1994, and 2002-03.
The mechanism in Australia is particularly potent because of the combination of drought and the Indian Ocean Dipole (IOD), which often co-occurs with El Niño. A positive IOD strengthens the drying effect over Australia. When both ENSO and IOD are in their dry phases simultaneously — as happened in 1997 and 2015 — the impact on fuel dryness is compounded, creating conditions in which fires can jump containment lines and produce extreme fire behavior.
North America and Other Fire-Prone Regions
The El Niño-wildfire connection in North America is more complex than in the tropics. El Niño typically brings wetter conditions to California and the southern United States, which can suppress fire risk by building up fuel moisture. However, wet winters also promote heavy grass growth, which then dries out in summer and can increase fire risk in the following fire season — a "fuel loading" effect that depends on the timing of the wet-to-dry transition. This is known as the "El Niño hangover" effect. British Columbia and the Pacific Northwest can experience drier-than-normal summers during El Niño, particularly during the decaying phase of strong events, increasing forest fire risk in Canada's western provinces.
In Central America, El Niño-driven drought creates conditions for large fire seasons in the "Dry Corridor" stretching from Guatemala through Honduras and Nicaragua. The 2015-2016 event produced an unprecedented fire season in the Maya Biosphere Reserve in Guatemala, burning 15,000 hectares of protected tropical forest.
Regional Fire Risk Summary
| Region | El Niño Fire Risk | Primary Fuel Type | Historical Worst Event |
|---|---|---|---|
| Indonesia / Borneo | Very High | Peat swamp forest, rainforest | 1997-98: 8-10 million ha burned |
| Amazon (eastern & southern) | High | Tropical moist forest | 2015-16: 1.6-3.0 Gt CO2 emissions |
| Eastern Australia | High | Eucalypt forest, grassland | 1982-83 Ash Wednesday fires |
| Southern Africa | Moderate-High | Savanna, woodland | 1991-92: widespread savanna fires |
| Central America Dry Corridor | Moderate | Tropical dry forest | 2015: Maya Biosphere fires |
| Pacific Northwest (US/Canada) | Moderate | Conifer forest | Variable by event strength |
Climate Change and Future Fire Risk
As the global climate warms, El Niño-driven wildfire risk is expected to increase across multiple dimensions. Higher background temperatures mean that the additional warming during El Niño events pushes fire weather conditions beyond critical thresholds more often. Studies projecting fire risk under climate scenarios consistently show that the area burned in El Niño-affected regions will increase substantially by mid-century. This is particularly concerning for the Amazon, where the combination of deforestation, selective logging, and more frequent extreme El Niño events could push large portions of the forest past a tipping point into a fire-prone, degraded state. The global tally of fire emissions during El Niño years, already a significant contributor to the carbon cycle, is projected to grow — adding yet another feedback loop between climate and fire.