Wildfire-generated ozone undermines Amazon's carbon-absorbing capacity
New research from the University of Exeter, ETH Zurich, and James Cook University reveals that ground-level ozone produced by Amazon wildfires significantly impairs the rainforest's ability to absorb atmospheric carbon dioxide. The study calculated that fire-driven ozone damage reduces Amazon carbon uptake by approximately 24% of the carbon emitted by the fires themselves, creating a dual climate impact through both direct emissions and reduced absorption capacity. This effect intensifies during major droughts, particularly those linked to El Niño events, with forecasters warning of a potentially intense El Niño developing in 2026.
Ground-level ozone forms when wildfire emissions interact with sunlight in the atmosphere. This pollutant damages leaf tissue in surviving trees, impairing their capacity to extract CO2 from the air—a process essential to the forest's role as a global carbon sink. The research team analyzed three decades of data to quantify this effect, finding it particularly pronounced during severe drought conditions.
The timing of wildfires relative to climate cycles amplifies the damage. Major Amazon droughts have coincided with El Niño warming events in 1997–98, 2015–16, and 2023–24, each creating conditions that intensify both fire activity and ozone formation. The 2023–24 event showed nearly double the ozone damage compared to the previous decade's average, suggesting a concerning pattern as another potentially intense El Niño cycle approaches.
This research may influence climate modeling and carbon credit frameworks, as previous calculations of Amazon carbon sequestration may have overlooked ozone-induced losses. Agricultural regions bordering the rainforest could face increased pressure for stricter fire management practices if policymakers incorporate these findings into environmental regulations. The results may also inform disaster preparedness strategies, particularly in years when El Niño conditions are forecast, potentially affecting land-use planning and international climate agreements that depend on accurate forest carbon assessments.