
In our annual series on forest loss trends in the Amazon (MAAP #244 & MAAP #229), we observed that the two most recent intense fire seasons, 2016 and 2024, immediately followed major El Niño events.
For example, extreme drought conditions created by a strong El Niño in late 2023 created extreme drought conditions the following year, enabling widespread fires across the Amazon in 2024. In contrast, the reduced fires of 2025 were associated with the moister conditions of La Niña.
For background, the definition of El Niño is based on warm sea surface temperature in a specific zone of the Pacific Ocean several hundred kilometers off the coast of South America (Figure 1).
Specifically, a Sea Surface Temperature Anomaly (SSTA) above 0.5 degrees Celsius in the El Niño 3.4 Zone is classified as an El Niño event (See Methods section for details). Anomalies above 1 degree C are a moderate event, and above 2 degrees C, a very strong event.
We took this SSTA data annually from 2002 to 2025 for the 3-month period of October-November-December, which typically correlates with peak temperature anomalies.
We then analyzed this data in relation to the following year’s fire-caused primary forest loss (data from the University of Maryland). We focused the analysis on years with at least a weak El Niño (SSTA > 0.5).
Results

Filtering the dataset for El Niño years (SSTA > 0.5 degrees C) isolates 8 specific historical events (2002, 2004, 2006, 2009, 2014, 2015, 2018, and 2023).
Of these events:
Four were Weak El Niño (SSTA 0.5- 0.9): 2004, 2006, 2014, and 2018;
Two were Moderate (SSTA 1.0 – 1.4): 2002, 2009;
One was Strong (SSTA 1.5 to 1.9): 2023;
And one was Very Strong (SSTA ≥ 2.0): 2015.
To analyze the delayed (lagged) impact, the SSTA from each year (Year t) is paired directly with the Fire Primary Forest Loss Area from the following year (Year t+1).
See Figure 2 for the visual correlation between El Niño events (blue) and primary forest loss from fires (red).
Note the initial observation that prompted this study: the major peak in fires in 2016 following the Very Strong El Niño of 2015, followed by the record-breaking fire season in 2024 following the Strong El Niño of 2023.
Despite a limited sample size (only 8 El Niño events since 2000) and limited statistical power, the analysis reveals a clear, strong positive relationship between the strength of El Niño events (that is, magnitude of the sea surface temperature anomaly) and the severity of the following fire season.
The strength of this relationship approaches the traditional margin of statistical significance (probability value under 0.05), with a probability value of 0.08 (see the Annex for details).
Thus, the data do indicate a potential escalating relationship between El Niño and Amazon fires.
Most notably, the two highest sea surface temperature anomalies —2015 (+2.34) and 2023 (+1.49)—directly preceded the two largest fire seasons, 2016 (1.76 million hectares) and 2024 (2.79 million hectares), respectively.
Low-tier warm anomalies (like +0.52 or +0.73) correspond to lagged fire sizes under 160,000 hectares.
Discussion
As detailed above, the available data indicates a strong positive correlation between the severity of El Niño events and the intensity of the Amazon fire season the following year.
This correlation is anchored by two key events that prompted this analysis in the first place: the peak fire season in 2016 following the Very Strong El Niño of 2015; and the record-breaking fire season in 2024 (see MAAP #229) following the Strong El Niño of 2023.
There is currently an urgency regarding these findings due to the predicted Very Strong El Niño event (that is, SSTA > 2 degrees C) in late 2026 and implications for the 2027 fire season. Some predictions have the SSTA as the highest on record, even approaching 3 degrees C by November to December 2026.
The current SSTA (for May-June-July 2026) is +0.98 degrees C (Weak to Moderate El Niño), rapidly coming out of last year’s La Niña phase, and warming fast.
Thus, the best recent analogue is the Very Strong El Niño of 2015, and the subsequent burning of nearly 1.8 million hectares of primary Amazon forest the following year in 2016. The most recent analogue is 2023 (see Figure 1), and the subsequent record-breaking fire season of 2024.
We also raise the possibility that the impact on fires carries over to a second year following a major El Niño – this could account for the severe fire seasons of 2017 (1 million hectares) and 2025 (1.5 million hectares).
The weaker El Niño years show a consistent directional pattern but without the same magnitude response.
We also note a major structural break in the data: in general, fires are much greater starting in 2016 (average fire area pre-2016: ~150k ha; Post-2016: ~1.0M ha). This time frame slightly precedes, overlaps, and then continues after the President Bolsonaro administration (2019-2023), which weakened illegal deforestation enforcement policies. Thus, there may be a new modern elevated baseline of fire activity in the Brazilian Amazon.
Since El Niño typically peaks in November to December, which corresponds to the onset of the wet (monsoon) season, the mechanism for this correlation may be shutting down the convection engine driving the rainy season. The disruption of the wet season moisture flow could extend the dry and transition seasons, reducing precipitation, creating drier conditions, and preventing the soil from recovering its moisture, setting up the Amazon for an intense fire season.
It is worth noting that another recent study found that the years with the largest burned areas in the Peruvian Amazon between 2013 and 2024 coincide with the occurrence of El Niño events and drought conditions (Reference 10).
How ready are Amazonian countries for the upcoming 2027 El Niño fire season?
Experience of 2024
The 2023 El Niño and subsequent 2024 fire season exposed the depth of the preparedness gap across the Amazon basin. The responses that emerged were largely reactive, deployed well into a crisis that monitoring systems had anticipated months earlier. Brazil, Peru, and especially Bolivia were most affected among the Amazonian countries, and this review of institutional preparedness focuses on these three countries. Drier conditions created by El Niño, however, created an increased fire risk across the entire biome, affecting all countries.
Brazil mounted the most substantial national response, though it arrived belatedly. By August 2024 — almost three months since the wildfires started — a state of emergency was decreed in 45 municipalities and 48 Brazilian cities were put on high alert (Reference 1). In the end, fires directly impacted 1.9 million hectares, the highest on record (MAAP #229).
Peru also declared a national emergency during the 2024 crisis, unlocking emergency coordination powers and international assistance. In the end, however, fires impacted 47,574 hectares, more than double the previous high (MAAP #229).
Bolivia also had its worst fire season on record in 2024, as fires directly impacted 779,960 hectares, far surpassing the previous record (MAAP #229). The main cause of deforestation and subsequent fires was likely agrarian speculation. Two supreme decrees in 2024 granted zero tariffs and tax incentives to agribusiness, which triggered a surge in demand for land for monocultures of soy, sugarcane, and seed oils. This expansion was supported by existing regulations that expedite the clearing of up to 20 hectares. The government declared a national emergency and later a national disaster, but the response was hampered by weak enforcement: Bolivia’s fines for illegal forest burning (under $20/hectare) are roughly 2% of Brazil’s, and tensions between national and local government further slowed emergency coordination. To contain the disaster, the government declared an Ecological Environmental Pause, which suspended burning permits and placed the burned public lands under quarantine for five years. The Inter-American Commission on Human Rights’ special rapporteur documented how tensions between national and local governments hindered emergency responses, while policies aimed at aggressively expanding industrial agriculture had dried out large areas of the country, leaving ecosystems vulnerable to fire.
Changes implemented in 2025
Fire impact was much lower in 2025 relative to 2024 (1.5 million vs 2.8 million hectares of primary forest burned, respectively) (MAAP #244). Several Amazonian countries implemented stronger fire management policies in response to the 2024 fire season. The reduced burnt area, however, cannot be solely attributed to better institutional preparedness, as climate conditions were also more favorable, with La Niña bringing relief through higher humidity levels across the biome.
In February 2025, Brazil’s Environment Minister Marina Silva decreed a pre-emptive environmental emergency ahead of the fire season, giving authorities extra powers and resources to contain wildfires before they spread. The federal government committed to hiring an additional 250 federal firefighters and allocated 45 million reais to bolster state-level fire brigades across six Amazonian states (Reference 3). Other structural measures followed: Brazil’s Supreme Court ordered the federal government and all Amazon and Pantanal states to draw up emergency fire management plans, while the Ministry of Environment announced “governance offices” in 70 Amazon municipalities — supported by FUNBIO and UNDP — to provide vehicles, boats, drones, and training for fire prevention (Reference 4). The Prevfogo program, managed by IBAMA, was expanded as a platform integrating satellite-based detection with ground response. These combined efforts contributed to a measurable decline in fire activity in 2025 compared with the previous year (MAAP #244).
In Peru, in response to the 2024 events, the Ministry of Environment proposed a Forest Fire Prevention and Control Law to establish regional firefighting brigades and prohibit land-use change in areas affected by wildfires, though recent amendments to the Forest Law (Law No. 31973) may undermine this approach (Reference 5). Seven of Peru’s 24 regions have published forest fire prevention and risk reduction plans, and a Multisectoral Plan for Wildfire Response 2025–2027 is currently being developed, drawing on risk assessments that classify nearly 20% of national territory as high or very high fire risk.
In Bolivia, the legislative trajectory since 2024 has moved in the opposite direction. Agribusiness lobbies have pressured to roll back burning fines, and a land reform that would have accelerated deforestation in Santa Cruz and Beni, the departments that burned most severely in 2024, was enacted in the first half of 2026, and then repealed in the face of social protests (Reference 6). The country has been navigating its worst economic and political crisis in decades, and institutional preparedness for the 2027 fire season could be severely challenged under these conditions.
In terms of regional cooperation, the most significant recent development is the Operational Understanding for Preparedness and Response, approved by ACTO member countries in early 2026. This non-binding regional cooperation framework establishes mechanisms for coordinating mutual assistance among Amazonian countries when the magnitude of forest fires requires a joint response, facilitating the articulation of national capacities, exchange of operational information, and technical support during fire-related emergencies. Concurrent with its adoption, member countries agreed to establish the Forest Fire Response Committee (CRIF), a regional body tasked with developing technical instruments, operational procedures, and coordination mechanisms to improve preparedness and joint response (Reference 7).
In conclusion, the reduction in burnt area observed across the three countries in 2025 occurred under favorable climate conditions, which, as our analysis shows, are unlikely to be seen in 2027. The true test of institutional preparedness will come under El Niño-driven stress. The regional architecture, meanwhile, can only perform as well as its weakest national link. Under a degraded political landscape and without policy improvements since 2024, Bolivia could become the epicenter of the 2027 fire season.
Outlook for 2026 – 2027
From the FAO’s El Niño Fire Readiness checklist (Reference 8), there are five major components of readiness for next year’s 2027 fire season.
First is “Fire Awareness”, which includes understanding historical trends that distinguish an average season from an anomaly season, and what drives major fires (such as fuel load from recently deforested areas) that could be incorporated into Risk Reduction strategies.
As noted above, annual MAAP reports (MAAP #229, MAAP #244) provide historical trends for the Amazon regarding fire impact to primary forests. These reports allow for the identification of intense, or anomalous, fire seasons (such as 2024).
In terms of what drives major fires, previous MAAP reports have revealed the tight link between deforestation and fires in the Amazon (MAAP #189). That is, most major fires are burning recently deforested areas, and then may escape into surrounding forests, especially with extended dry conditions such as 2016 and 2024. For example, over 70% of major fires in the Brazilian Amazon burn recently deforested areas (MAAP #189). There is also a strong link between deforestation and fire in the Bolivian Amazon, where deforestation also often precedes fires, which may then escape into surrounding forests or savannahs.
Thus, one of the key strategies to minimize major fires in 2027 is to minimize new deforestation in 2026.
Second is the establishment of “Fire Danger Rating and Early Warning” systems and the provision of this information to stakeholders.
As the El Niño intensifies throughout 2026, this could include the monitoring of moisture or drought conditions and issuing respective warnings.
Third is “Fire Preparedness,” and includes guidance for prevention, detection, and suppression of fires based on the above rating and warning system.
In terms of prevention, fire-free agricultural practices could be promoted in 2026 and more strictly enforced in 2027, coordinating closely with local rural unions and cooperatives (Reference 9). Local community initiatives represent a critical component of this preparedness, serving as tangible examples of prevention, detection, and suppression mechanisms.
For instance, the Territorial Strengthening Actions implemented across the Amazon basin demonstrate this integrated approach: communities in Colombia, Peru, Bolivia and Ecuador are actively developing local capacities for fire detection, sustainable management (safe fire use) and early response, while promoting alternative practices to slash-and-burn agriculture.
This community-based approach is further strengthened by broader regional efforts, such as the CoRAmazonia program. This initiative promotes an Integrated Fire Management strategy that integrates technical, scientific, and traditional indigenous knowledge. Through platforms like ExpoMIF and the Amazon Network for Integrated Fire Management (RAMIF), the program highlights the crucial role of Indigenous peoples and traditional communities in fire governance, emphasizing the importance of community brigades, territorial monitoring, and the rescue of affected wildlife.
Fourth is “Pre-fire Season Activities,” which highlights whether agencies are adequately engaging stakeholders and setting up national agreements.
Fifth is “Fire Detection, Communication, and Dispatching,” which forms the real-time fire Response procedures and mechanisms.
In terms of detection, real-time fire monitoring should be integrated into national response protocols and field-level coordination.
For communication and dispatching, there could be the establishment of contingency plans to extinguish forest fires rapidly before they spread, focusing heavily on fires starting in recently deforested areas and expanding towards protected areas or Indigenous territories.
In Peru specifically (Reference 10), the most critical districts are concentrated in the Ucayali, Madre de Dios, and Huánuco regions. Regarding public budget allocation, there are gaps in the prevention of and response to forest fires, resulting in limited operational capabilities and significant disparities in the allocation and execution of public resources for disaster risk management. Overall, there is the need to strengthen systems for monitoring, early warning, planning, and institutional response regarding forest fires, prioritizing areas with the greatest historical vulnerability.
Methods
The analysis combined two primary data sources: 1) Relative Oceanic Niño Index (RONI) based on sea surface temperature anomaly (SSTA) and 2) annual primary forest loss from fires.
RONI, the standard used by NOAA for classifying El Niño (warm) and La Niña (cool) events in the eastern tropical Pacific, is the running 3-month average sea surface temperature (SST) for the Niño 3.4 region, minus the overall average tropical 3-month sea surface temperature anomaly (SSTA). For this study, we used the 3-month period of October-December for each year.
Events are defined as 5 consecutive overlapping 3-month periods at or above the +0.5 anomaly for warm (El Niño) events and at or below the -0.5 anomaly for cool (La Niña) events. The threshold is further broken down into Weak (with a 0.5 to 0.9 SST anomaly), Moderate (1.0 to 1.4), Strong (1.5 to 1.9), and Very Strong (≥ 2.0) events.
In addition to warm SSTA in the Pacific Ocean, Amazon drought conditions may also be influenced by warm SSTA in the North Tropical Atlantic Ocean (Reference 10), but our study did not account for this.
The fire analysis was based on 30-meter resolution annual forest loss data produced by the University of Maryland and also presented by Global Forest Watch. This Global Forest Loss due to fire dataset is unique in terms of being consistent across the Amazon (in contrast to country-specific estimates) and distinguishes forest loss caused directly by fire (note that virtually all Amazon fires are human-caused). The values included were ‘medium’ and ‘high’ confidence levels (code 3-4).
For the baseline, it was defined to establish areas with >30% tree canopy density in 2000. Importantly, we applied a filter to calculate only primary forest loss by intersecting the forest cover loss data with the additional dataset “primary humid tropical forests” as of 2001 (Turubanova et al 2018). For more details on this part of the methodology, see the Technical Blog from Global Forest Watch (Goldman and Weisse 2019).
The analysis was supported and reviewed by AI: Gemini and Claude
Annex
Because we have a constrained subset (N = 8), the statistical power is limited, but a clear, strong positive pattern is evident across several major metrics.
The Pearson Linear Correlation indicates a strong positive linear relationship between the magnitude of the warm anomaly and the next year’s fire area (r = +0.6146), approaching the traditional margin of statistical significance (p-value = 0.1049). This correlation is even stronger when we take the natural log of the fire area to account for natural fire activity (p-value = 0.0827).
Spearman Rank Correlation reaffirms that higher SSTA values rank alongside worse fire outcomes in the succeeding year ( +0.5476; p-value= 0.1600).
- Log-Transformed Pearson Correlation (r log): +0.6474
- Wildfire spread typically behaves exponentially rather than linearly. When we take the natural log of the fire area (ln{Fire}_t+1) to correct for this, the correlation strengthens to nearly +0.65, approaching the traditional margin of statistical significance (p < 0.10).
References
1. Lancet Regional Health – Americas / PMC. (2025). The 2024 South America ablaze: Health impacts and policy imperatives for protecting population health in an era of wildfires
2. IACHR (2025) REDESCA publishes report on wildfires in Bolivia and calls for urgent action to address impacts on human rights and ecosystems
3. Mongabay (2025). Brazil declares environmental emergency ahead of 2025 fire season.
4. Muggah, R., & Szabo, I. / Mongabay. (2025). Brazil is speeding-up forest fire prevention to avoid dangerous tipping points in the Amazon.
5. Lancet Regional Health – Americas / PMC. (2025). The 2024 South America ablaze. (See footnote 3.) Peru-specific governance section
6. Copa Pabón, M. V. (2026, May 15). Indigenous protest forces repeal of land privatization law in Bolivia.
7. ACTO. (2026, February–March). ACTO member countries approve Operational Understanding for Preparedness and Response to Forest Fires in the Amazon Region.
8. FAO El Niño Fire Readiness checklist (2024) As presented in the Global Fire Management Hub and informed by its Integrated Fire Management Voluntary Guidelines
9. Brown F, et al (2026). Alert related to the coming severe dry period, heat waves, fires, smoke and climate in the Madre de Dios-Peru, Acre-Brazil, Pando-Bolivia (MAP) Region – 30 April 2026. Foster Brown
10. ACCA (2026) El Niño y los incendios forestales en la Amazonía peruana, ¿qué podemos esperar para la temporada 2026-2027?
Citation
Finer M, Bodin B (2026) Implications of upcoming major El Niño event on Amazon fires. MAAP: 248.
Acknowledgements
We thank colleagues from the following organizations for helpful comments on the report: Conservación Amazónica – ACEAA in Bolivia and Conservación Amazónica – ACCA in Peru.
This work was supported by Norad (Norwegian Agency for Development Cooperation).
















































Per the Brazilian Constitution, the concession of “lavra garimpeira” or exploitation permit for artisanal mining is irregular within indigenous territories






























































