Researchers from the Institute of Information and Communications Technologies (ITACA) at the Universitat Politècnica de València (UPV), in collaboration with the Natural Resources Institute Finland (Luke), have developed a methodology that enables more accurate estimates of greenhouse gas emissions from large Mediterranean forest fires.
The method has been applied to the 2022 Bejís fire (Castellón), which affected 18,538 hectares. According to the study, the fire had an impact on global warming equivalent to 626,000 tonnes of carbon dioxide (CO₂), a figure higher than the emissions generated in a year by the city of Valencia and close to 0.22 per cent of Spain’s annual greenhouse gas emissions.
The study, published in the scientific journal «Fire«, was developed by Helena van den Berg Sesma, Edgar Lorenzo-Sáez, Victoria Lerma-Arce, and José Vicente Oliver-Villanueva from ITACA-UPV, together with Mauricio Acuna from the Natural Resources Institute Finland.
«The results highlight that wildfires not only cause economic, environmental, social and emotional losses, but also have a significant impact on the climate», says Helena van den Berg Sesma, a researcher at ITACA-UPV and lead author of the study.
A less visible consequence of wildfires
When a forest burns, some of the carbon stored over many years in trees, shrubs, and other vegetation is released back into the atmosphere as greenhouse gases. At the same time, the loss of forest cover can temporarily reduce the ecosystem’s capacity to absorb CO₂.
«Global warming resulting from climate change creates conditions that increase the risk of fire, while large wildfires can release greenhouse gases into the atmosphere and temporarily reduce ecosystems’ capacity to absorb carbon», explains Edgar Lorenzo-Sáez, a researcher at ITACA-UPV.
The authors therefore emphasise the importance of tackling large-scale wildfires not only through firefighting, but also through prevention, adaptation to climate change and sustainable forest management.
The importance of the Mediterranean landscape diversity
One of the key innovations of the research is its consideration of the Mediterranean landscape’s diversity.
To this end, the methodology combines Sentinel-2 satellite imagery with information on the amount of biomass present before the fire, the type of vegetation, and the intensity of burning in each area.
«Unlike models that assign a single type of vegetation to each area, the new approach identifies the coexistence of different types of vegetation cover within the same area,» explains José Vicente Oliver-Villanueva, a researcher at ITACA-UPV.
This information enables a more realistic representation of landscapes where conifers, scrub, herbaceous vegetation, and deciduous trees coexist.
Areas containing conifers, particularly where these coexisted with scrub and herbaceous vegetation, contributed the most. The study thus demonstrates that it is not enough to know how many hectares have been burnt to calculate a wildfire’s climate footprint: one must also know what vegetation was present, how much biomass it contained, and how intensely it burnt.
«The results from the Bejís fire show that, overall, the highest emissions were concentrated in the most severely affected areas. Areas with high and moderate-to-high damage levels together accounted for more than 81 per cent of the estimated emissions,» says Victoria Lerma-Arce.
A tool for better prevention and management
This information can be particularly useful for preventive forest management, as it allows identification of areas and vegetation types that could generate the highest emissions in the event of a major fire.
«Incorporating this data into forest planning can help prioritise actions relating to vegetation and forest fuels, promote more resilient landscapes, and reduce both the risk of high-intensity fires and their potential climate impact,» emphasise the authors of the research.
Finally, they highlight that the developed methodology can help improve regional and national greenhouse gas inventories and can be applied to other large Mediterranean wildfires, provided that adequate information on vegetation and biomass is available.
The research was carried out with support from the European projects INFORMA Forests, which focuses on science-based integrated forest management, and URBAN-FLOW.
DOI: Severity-Driven Assessment of Greenhouse Gas Emissions from Large Mediterranean Wildfires Using Remote Sensing and Vegetation Mosaics. Helena van den Berg Sesma, Edgar Lorenzo-Sáez, Victoria Lerma-Arce, José Vicente Oliver-Villanueva, Mauricio Acuna. Fire. https://doi.org/10.3390/fire9040167