Posted by Design Studio
9 December 2025
Challenge 1: Tree Biomass
Context
Fires have shaped Earth’s ecosystems for hundreds of millions of years. Nowadays fires, both natural and human-induced, remain a major source of greenhouse gases and aerosols, affecting atmospheric composition, climate, and air quality. Since the early 2000s, global estimates of carbon emissions from landscape fires (covering forests, savannas, croplands, etc.) generally converged around ~2 petagrams of carbon per year (Pg C yr⁻¹), based on coarse satellite burned-area products and biogeochemical modelling. However, many fires, particularly small or agricultural ones, were likely missed because satellite resolution was too coarse. There has been growing recognition that those “small fires” may be frequent and cumulatively significant, meaning the earlier global fire carbon budgets might substantially underestimate actual emissions.
Methods
The new version of the Global Fire Emissions Database version 5 (GFED5) integrates several methodological improvements over its predecessors: higher-resolution satellite data (including fine-scale burned area mapping from e.g. Sentinel-2 and Landsat), better modelling of fuel loads using a 500-m spatial-resolution biogeochemical model, and revised emission factors (the amount of gas or aerosol emissions produced per unit vegetation burned) using updated databases.
Results
With GFED5, we estimate a global average of 3.4 Pg C yr⁻¹ from landscape fires over 2002–2022, significantly higher than previous global estimates used in many climate assessments and carbon budgets. The inclusion of small fires and improved burned-area mapping brings emission estimates more in line with atmospheric observations (e.g., satellite measurements of carbon monoxide or aerosols) especially during major regional fire events. The revised dataset provides a more comprehensive record, supporting better fire modelling and improving interpretation of fire impacts on atmospheric trace gases, aerosol burden, and long-term carbon cycling. The data is publicly available from https://www.globalfiredata.org
Mean annual fire carbon emissions, averaged over 2002-2022. Most emissions stem from frequently burning landscapes, such as savannas, where vegetation is adapted to fire. Fires used in the deforestation frontiers in South America and Asia are a net source of carbon as their emissions are usually not compensated for regrowth after a fire, and although fires also occur naturally in the boreal region, the frequency and intensity is increasing there due to climate change.
