Unveiling the Hidden Green House Gases Footprint of Amazonian Forest Fires

Frequent and extensive fires, which do not occur naturally in Amazonia, are a neglected net source of anthropogenic emissions in national and global carbon budgets. More fires are expected in Amazonian humid forests with the increase of severe droughts combined with land cover change. However, it is challenging to integrate them into estimates of emissions from Land Use, Land-use Change and Forestry (LULUCF). Amazonian forest fires are still not accurately represented in the global carbon budgets. A key reason for that is the absence of long-term carbon fluxes (post-fire decomposition emissions and uptake from regrowth) in the models. Here, we combine spatial datasets with a large-scale in-situ assessment of carbon stocks to quantify the unaccounted emissions from burned standing forests. We developed a spatial bookkeeping model and applied it over 3 decades to estimate GHG emissions in burned standing forests at 30m resolution. We found that 187,900km ² of remaining forests have burned at least once across the Brazilian Amazon, emitting 1.8 Pg of CO ₂ eq over 33 years. Our results highlight the crucial importance of immediately accounting for Amazonian forest fires emissions, as they are additional to deforestation net emissions and their lagged effects should be accounted into both national and global emission systems. One-Sentence Summary : Amazon forest fires are additional to deforestation and represent a significant unaccounted source of carbon emissions.