Amazon fires in 2024 may have released up to three times more carbon than earlier estimates suggested

Amazon fires in 2024 may have released up to three times more carbon than previously estimated

The fires that swept through the Amazon and the Cerrado in 2024 may have released significantly more carbon into the atmosphere than previous estimates indicated, according to new research funded by the European Space Agency. According to the results published on March 25, 2026, the actual emissions linked to that fire season could be between 1.5 and three times higher than earlier calculations. This is a finding that not only changes the view of the scale of last year’s ecological disaster in South America, but also raises serious questions about how reliable current global models are that calculate carbon flows, climate scenarios, and the burden of emissions from major fire seasons.

The research concerns fires that during 2024 affected vast areas of the Amazon rainforest and the Cerrado, a savanna and forest mosaic that covers approximately one fifth of Brazilian territory and also extends toward Bolivia and Paraguay. The European Space Agency states that this was the most intense fire activity in that zone in the last twenty years, while additional scientific papers published after the fire season warn that 2024 brought a peak of forest disturbances across the wider Amazon region, along with a sharp rise in fire-induced forest degradation. This further confirmed that last year’s season was not just another bad year, but an event that stands out in scale even compared with the already severe episodes of earlier decades.

Why the new research matters

Previous estimates of emissions from fires generally relied on classic indicators such as burned area and so-called fire radiative power, that is, the amount of energy a fire releases and that satellites can detect. Such models are useful for the rapid monitoring of fire events, but the new research shows that in the Amazon environment they may miss an important part of the real problem. Especially important is what is not easily seen in short and intense flames: the prolonged smouldering of woody material, dead wood, and vegetation remains, which can produce large amounts of gases and pollutants even after the most visible flames have weakened.

The paper published in Geophysical Research Letters was led by the Technical University of Dresden in cooperation with the Royal Netherlands Meteorological Institute, known as KNMI, and the company BeZero Carbon. The researchers focused on the fire season during August and September 2024, and for the analysis they applied artificial intelligence to satellite observations of carbon monoxide. In this case, that gas is used as a proxy for estimating carbon dioxide emissions, because it is easier to track accurately from space than CO2 itself. When such satellite data are combined with fire models, a more detailed picture is obtained of what was actually happening in the smoke plumes above the central part of South America.

According to the explanation of lead author Jos de Laat of KNMI, the research covered an area of about four million square kilometres, with the fiercest fires and the highest pollution concentrations recorded along the Brazil-Bolivia border. It was precisely there that satellite observations and modelled values did not match as would be expected. Scientists therefore concluded that there are “gaps” in current methods, that is, that some emission sources are clearly not being captured well enough by existing approaches. In other words, the problem is not only that a large area burned, but also the type of combustible material, the way it burned, and the duration of the combustion process.

Smouldering as a hidden source of large emissions

One of the key conclusions of the research is that prolonged smouldering plays a much greater role than previously assumed. When fire reaches grass or lower vegetation, combustion is usually faster and more visible. But in tropical forest and transitional ecosystems, a large share of emissions can arise when trunks, branches, and other woody remains burn for a long time. Such combustion does not necessarily create spectacular tongues of flame that would be easily registered as an extremely powerful fire, but it can still release large amounts of carbon monoxide, particles, and other compounds linked to air degradation and climate effects over a long period.

This is an important message both for climatology and for public policy. Global carbon budgets, national emission reduction strategies, and international climate models depend on knowing as accurately as possible how much greenhouse gas is released from forests, peatlands, savannas, and other fire-affected ecosystems. If emissions from one of the world’s most important forest systems are being systematically underestimated, then it is possible that part of the broader picture of the global carbon balance also needs correction. This is particularly important at a time when climate policies rely on very precise estimates of carbon sources and sinks and when every major error can spill over into estimates of future warming.

Why carbon monoxide is monitored, not just carbon dioxide

At first glance, it may seem unusual that a serious study of CO2 emissions relies on measurements of carbon monoxide. But the scientific reason is fairly clear. Carbon dioxide is the main greenhouse gas linked to human activity, but it is already naturally present in the atmosphere in high and relatively stable concentrations. Small changes linked to individual fire episodes are therefore harder to separate from the background picture from space. Carbon monoxide, by contrast, exists in much lower concentrations under natural conditions and is far more variable, so satellites can detect it more easily when fires suddenly raise its levels.

This does not mean that carbon monoxide matters only as a technical indicator. It is also a toxic gas that seriously degrades air quality, especially when smoke lingers over populated areas or travels over long distances. In the region along the Brazil-Bolivia border, on which the researchers focused especially closely, the consequences for air quality were severe. That is why this study is important not only for climatologists and emissions modellers, but also for public health, crisis management, and early warning systems during major fire seasons.

The role of Sentinel satellites and artificial intelligence

A central place in the research was held by the Sentinel-5P satellite, the first Copernicus mission dedicated to atmospheric monitoring, launched in October 2017. Its Tropomi instrument measures trace gases and aerosols, including nitrogen dioxide, ozone, formaldehyde, sulphur dioxide, methane, and carbon monoxide. The European Space Agency points out that Sentinel-5P provides global daily coverage and is particularly suitable for monitoring carbon monoxide thanks to its fine spatial resolution and more sensitive detectors than those available to earlier generations of instruments.

But the researchers did not stop at a single satellite. The paper also combined data from the Sentinel-2 and Sentinel-3 missions to improve both the estimation and verification of emissions. Such integration of multiple sources makes it possible to better understand burned areas, vegetation characteristics, fuel conditions, biomass moisture, and the dynamics of the fire itself. Artificial intelligence was not used as a replacement for physical models, but as a tool to accelerate highly demanding calculations. The scientists state that this is precisely what made comparisons across multiple years and multiple regions possible, something that would have been much slower and harder to carry out with conventional computational methods.

Such an approach is especially important because modern fire monitoring is increasingly shifting from the simple recording of what has already burned toward understanding why combustion was so intense and what its actual consequences are for the atmosphere. In that sense, satellites are not just a tool for producing impressive images of smoke from space, but a key source of data for testing the models on which international emissions estimates are based. If a satellite consistently “sees” more pollution than models predict, that is a warning that an important part of the process is missing somewhere in the methodology.

Broader context: fires, drought, and deforestation

Fires in central South America are not a new phenomenon, but their destructiveness grows when prolonged drought, high temperatures, forest degradation, and human activities such as land clearing or burning vegetation for land conversion come together. In official statements by the Brazilian government during 2024 and 2025, it was repeatedly stated that the region had been hit by one of the most severe droughts in recent years, while European and international sources warned that heatwaves and a lack of rainfall had further increased the flammability of the landscape. In such conditions, even ecosystems that are not usually prone to frequent fires become more vulnerable, especially when they have already been weakened by logging, fragmentation, and edge effects.

It is especially important to understand that a decline in officially recorded deforestation does not automatically mean lower fire risk in the short term. In November 2024, Brazil announced that the official deforestation rate in the Amazon in the period from August 2023 to July 2024 had fallen by more than 30 percent, while the Cerrado recorded its first decline in five years. That is a politically and environmentally important shift. Yet scientific papers analysing 2024 show that forest degradation and burning, especially during the extreme drought, still reached levels that cause deep concern. In other words, fewer felled trees in official statistics do not cancel out the fact that a huge area of forest may have been damaged by fire, smoke, and prolonged smouldering.

That difference between deforestation and degradation is often overlooked in public debate. Deforestation usually means a more complete loss of forest cover, while degradation may include partial forest damage, reduced biomass, structural disruption, and greater vulnerability to future fires. That is precisely why 2024 represents a special warning for the Amazon: even when part of formal clearing slows down, extreme drought and fires can weaken the resilience of the forest system from within and push it toward a state in which it is harder to recover.

Consequences for climate models and future policies

The finding that emissions may have been up to three times higher than earlier estimates could have concrete consequences for several levels of decision-making. First, it could lead to corrections in operational databases that track fire emissions in near real time. Second, it could affect scientific models that estimate how much carbon tropical forests can still absorb and how much they are beginning to return to the atmosphere because of degradation, drought, and fires. Third, such results are also important for political debates on climate commitments, because decisions on climate change mitigation depend on the most accurate possible understanding of actual emission sources.

The European Space Agency emphasises that the methodologies and data developed in this project will be included in future European research projects and in the Copernicus Atmosphere Monitoring Service, known as CAMS. That service already uses systems for estimating fire emissions based on satellite observations, above all through the Global Fire Assimilation System. The new research suggests that precisely such operational systems could benefit from improvements that better recognise slower, longer-lasting, and at first glance less conspicuous forms of combustion, which in Amazon conditions carry a large emissions burden.

In a broader sense, the case of the Amazon and the Cerrado shows how dangerous it is in climate science to rely on simplified assumptions. A fire is not just a red dot on a map and a number of burned hectares. It is a combination of fuel, moisture, burn time, meteorological conditions, vegetation structure, and human activity. When one of those elements remains underestimated, the total climate damage may also be underestimated. That is precisely why the new analysis from 2026 goes beyond the story of one fire season: it warns that the true climate cost of major fires could be greater than we were prepared to admit, and for the Amazon, as one of the world’s key reservoirs of carbon and biodiversity, this has global significance.

Sources:
- European Space Agency (ESA) – official announcement of the new research and the estimate that wildfire emissions in the Amazon in 2024 may have been 1.5 to 3 times higher than earlier estimates (link)
- Geophysical Research Letters – scientific paper on satellite observations, carbon monoxide, and underestimated wildfire emissions in the Amazon in 2024 (link)
- European Space Agency (ESA) – data on the Sentinel-5P mission and the Tropomi instrument, including daily global coverage and atmospheric gas monitoring (link)
- Government of Brazil / Planalto – official data on the decline of deforestation in the Amazon and the Cerrado during 2024, important for the broader context of fires and forest degradation (link)
- Biogeosciences – paper on extensive Amazon forest degradation caused by the 2024 fires and record emissions associated with that season (link)
- Copernicus Atmosphere Monitoring Service (CAMS) – explanation of operational global fire monitoring and emission estimation through the GFAS system (link)
- Sense4Fire – official project page on satellite monitoring of fuel, fire dynamics, and emissions, with a focus on the Amazon and the Cerrado (link)