Abstract
Abstract. Atmospheric emissions from wildfires in Portugal were estimated yearly over the period 1990–2008 using Landsat-based burnt area maps and land cover maps, national forest inventory data, biometric models, and literature review data. Emissions were calculated as the product of area burnt, biomass loading per unit area, combustion factor, and emission factor, using land cover specific values for all variables. Uncertainty associated with each input variable was quantified with a probability density function or a standard deviation value. Uncertainty and sensitivity analysis of estimates were performed with Monte Carlo and variance decomposition techniques. Area burnt varied almost 50-fold during the study period, from about 9000 ha in 2008 to 440 000 ha in 2003. Emissions reach maximum and minimum in the same years, with carbon dioxide equivalent (CO2eq.) values of 159 and 5655 Gg for 2008 and 2003, respectively. Emission factors, and the combustion factor for shrubs were identified as the variables with higher impact on model output variance. There is a very strong correlation between area burnt and emissions, allowing for good emissions estimates once area burnt is quantified. Pyrogenic emissions were compared against those from various economy sectors and found to represent 1% to 9% of the total.
Highlights
Environmental impacts of wildfires affect abiotic and biotic ecosystem components, including flora, fauna, soil, water, air, and cultural resources (Brown and Smith, 2000)
Barbosa et al (2009) presented an analysis of wildfire numbers and area burnt in Europe using data from the European Forest Fire Information System (EFFIS), which show that an annual average (2000– 2005) of about 95 000 fires occurred and 600 000 ha were burnt in 23 European countries
Inter-annual variability in area burnt was very high during the study period, ranging from over 300 000 ha and over 400 000 ha in 2005 and 2003, respectively, to a low of 9000 ha in 2008, i.e., over one order of magnitude (Fig. 1)
Summary
Environmental impacts of wildfires affect abiotic and biotic ecosystem components, including flora, fauna, soil, water, air, and cultural resources (Brown and Smith, 2000). Several studies have analysed various aspects of the atmospheric impacts of wildfires in Europe, ranging from the more general, such as air quality issues (Miranda et al, 2009a) and emissions assessment (Barbosa et al, 2009), to more specific or local, including particulate matter emissions, transport, and radiative effects (Hodzic et al, 2007), mercury emissions (Cinnirella and Pirrone, 2006), emissions and global warming relationships (Miranda et al, 1994), the impact of Eastern European agricultural fires on Arctic air pollution (Stohl et al, 2007), and satellite tracking of emission and transport of pollution from an extreme fire episode (Turquety et al, 2009). About two-thirds of the fires were recorded in five southern European countries (France, Greece, Italy, Portugal, and Spain) where an annual average of about 500 000 burnt every year.
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