Amazon's old-growth forest wildfires surge 152% in 2023, study show

Despite a decrease in the rate of deforestation in the Brazilian Amazon in 2023, the region now faces a new challenge: wildfires that are affecting the untouched native vegetation.

A recent study published in the journal Global Change Biology highlights a concerning trend, with wildfires in old-growth forests increasing by 152% compared to 2022. This surge comes despite an overall decrease of 16% in the total number of fires across the Amazon and a 22% drop in deforestation.

Forest fires surge due to drought

Satellite image analysis conducted by the authors revealed a significant rise in forest wildfires, from 13,477 in 2022 to 34,012 in 2023. Drought emerges as the primary culprit behind this escalation, as the region experiences longer and more frequent dry periods. Previous droughts in 2010 and 2015-16 left the forest vulnerable to fire and caused fragmentation of the plant cover. The situation worsened with another severe drought that began last year and persists to this day.

Data from the National Space Research Institute (INPE) indicates a notable increase in the number of fires throughout the Amazon during the first three months of 2023, reaching 7,861. This figure surpasses the numbers observed in the previous eight years and constitutes more than half of Brazil's total fires.

The Amazon takes precedence, followed by the Cerrado region, which recorded 25% of the fires. Previously, the highest number of first-quarter fires recorded was 8,240 in 2016.

Guilherme Augusto Verola Mataveli, the corresponding author of the study and a remote sensing specialist with INPE's Earth Observation and Geoinformatics Division, emphasized the significance of understanding the geographic pattern of the fires, stating, "Each of the areas concerned requires a different response. Our analysis pointed to more fires in old-growth forest areas than in previous years, which is alarming not just because of the loss of vegetation, which is invariably followed by deforestation, but also because the carbon stored by the forest becomes carbon emissions when it burns."

More fires near deforestation frontier

Last year, some members of the research group published another article indicating a surge in wildfires along an emerging deforestation frontier in the Boca do Acre area in the southwest of Amazonas state, North Brazil, between 2003 and 2019.

"Old-growth forest stores larger amounts of carbon, which becomes greenhouse gas emissions when it burns, contributing to climate change. Another negative effect relates to public health problems. In October 2023, Manaus [the capital of Amazonas state] had the worst air quality of any city in the world bar one," highlighted Mataveli.

Furthermore, burnings escalated in other states, notably in Pará, where the number of old-growth forest fires surged to 13,804 in 2023, up from 4,217 in 2022.

The situation in Roraima is dire, with over half of the fires detected in the Amazon in 2024 occurring in this state, which boasts the fifth-largest Indigenous population in Brazil (97,320). Fourteen out of its 15 municipalities declared a state of emergency in March due to fires. The severe drought left Indigenous communities without access to food and exposed to respiratory disorders, among other issues, forcing schools to close due to smoke.

In response to Agência FAPESP, the National Center for Forest Fire Fighting and Prevention (PREVFOGO), an arm of IBAMA, the main federal environmental agency, affirmed its collaboration with other institutions since November 2023 to combat and prevent forest fires in Roraima. More than 300 firefighters and four aircraft have been deployed in this campaign since January.

"Climate change is a key driver of the increase in forest fires, and El Niño has also added risk owing to its links with the prolonged drought in the region. We stress the importance of the firefighting efforts of state and municipal environmental authorities in collaboration with federal agencies. This partnership is fundamental to assure strategic and effective prevention of forest fires," emphasized the IBAMA/PREVFOGO statement.

Forest resilience

Tree mortality due to fire in primary forest areas often exceeds 50% of the above-ground biomass, significantly reducing the volume of carbon stored in the Amazon over the long term.

In February, Brazil witnessed the highest carbon emissions from fires in 20 years, totaling 4.1 megatons, with Roraima leading the tally, according to the Copernicus Atmospheric Monitoring Service, a part of the European Union's space program.

Additionally, wildfires weaken forest resilience, impacting the forest's ability to maintain a humid microclimate under the canopy that retains and recycles moisture within the ecosystem.

The researchers also highlight the challenge posed to traditional subsistence farmers by the increase in invasive wildfires, as these farmers typically use controlled fire as a land management strategy.

According to Luiz Aragão, the leader of the research group and the paper's last author, "The Amazon is becoming increasingly vulnerable environmentally, socially, and economically due to the persistent fire problem." Despite recent decreases in deforestation rates, the affected area continues to expand.

"We predicted this in an article published by our group in 2010 in the journal Science," Aragão remarked. "Both deforested areas and areas where the forest is currently being destroyed serve as active sources of fire ignition by humans. Deforestation fragments the landscape, creating more boundaries between forested and open areas, rendering old-growth forest areas more susceptible to fire."

"The aggregate impact of extreme droughts like the current one, alongside landscape fragmentation, continuous use of fire, more areas of fire-degraded forest, illegal logging, and edge effects will make the forest increasingly flammable. Urgent measures are needed to mitigate fires and maintain the Amazon as Brazil's greatest asset to achieve sustainable national development," highlighted the report.

Furthermore, the paper advocates for more command-and-control operations, the establishment of more numerous and better-equipped fire brigades, and the constant improvement of monitoring systems.

"Through the use of artificial intelligence, we can develop systems that not only indicate where fires are occurring but also predict where they're most likely to break out in the future. This allows us to focus preventive action on specific areas," added Mataveli.