2003-2010 Fire season and extreme fire events occurred in Sardinia Island (Italy): a focus on carbon loss and greenhouse gas emission

Forest fires play a crucial role in natural and unmanaged ecosystems, with both negative and positive impacts on all biosphere components, and with reverberations on different scales, from local to global. One of the main primary effects is the production of a remarkable amount of greenhouse gases and solid particulate matter due to biomass combustion. The large amounts of carbon that fires release into the atmosphere could approach levels of anthropogenic carbon emissions, especially in years of extreme fire activity (e.g Greece 2007, Portugal 2003 and 2005). The state of the art in calculating fire emissions for a specific species from vegetation fires follows the work of Seiler and Crutzen (1980), and requires quantification of three parameters: area burned, the amount of biomass burned, and the emission factors associated with each specific chemical species. A number of studies -from global to continental to national scale- used this equation. However, several errors and uncertainties can affect the emission estimation, due to the assessment consistency of the various parameters involved in the equation. It includes also the spatial and temporal distribution of burning, appropriate fuel load evaluations, and gaseous emission factors for different fuel fractions and fire types. Model approaching can contribute to appraise fuel consumption and the resultant emissions. In this context, more comprehensive and accurate data inputs would be of valuable help for predicting and quantifying the source and the composition of fire emissions. In this work, we present results of a quantitative analysis of fire emission estimate in Sardinia Island (Italy) from 2003 to 2010 fire season and extreme fire events, evaluating also the contribution to total emission of the different fuel types burned. In order to reduce bias in predicting and quantifying the source and the composition of fire emissions and achieve realistic estimates, particular attention was paid to develop and survey comprehensive and accurate data inputs.The methodology combines fuel, fire and weather observations with a fire emission model (FOFEM - First Order Fire Effect Model, Reinhardt et al., 1997). The input and output data are assembled into a Geographical Information System (GIS) to facilitate their manipulation and display. The results showed the crucial role of appropriate fuel, fire, and weather data and maps to attain reasonable simulations of fuel consumption and smoke emissions. Carbon emission estimates are sensitive to pre-fire fuel loads, so the method used to establish initial fuel conditions is crucial. The FOFEM outputs and the derived smoke emission maps are useful for several applications including emissions inventories, air quality management plans, and emission source models coupled with dispersion models and decision support systems.