Estimating relationships between forest fires and greenhouse gas emissions: circular and cumulative effects or unidirectional causality?

Greenhouse gas emissions have relevant implications on increases in global temperatures. In turn, forest fires cause significant damage to populations and economic activities, compromising sustainable development and sustainability. However, sometimes, these two phenomena seem to be interrelated. The objective of the study presented here is to investigate the relationship between forest fires and gas emissions. This interrelationship was analysed for the European Union countries where forest fires have had relevant consequences (Portugal, Spain, France, Italy and Greece), over the last decades (1980-2012). In a first step, the level of correlation among greenhouse gas emissions (kt of CO2 equivalent) and the dimension of the forest fires (measured through the burnt area (ha)) was analysed. In a second phase, the causality between these two variables was examined. Finally, the most adjusted model for the relationship between the dimension of the forest fires and global warming was then estimated. It is worth highlighting that, in Portugal, Spain, France and Italy, there is significant correlation among the two variables. For Greece, significant correlation was only found with the variables in growth rates. On the other hand, the most adjusted models estimated for Portugal, Spain, France and Italy are nonlinear, and for Greece, a linear relationship was found. The directional causality varies across the several countries considered. For Portugal and France, considering values of 2012, an increase of 1 ha of burnt area increased the greenhouse gas emission in around 0.09 and 2.61 kt of CO2 equivalent, respectively. In Greece, when the burnt area (ha) growth rate increases 1 percentage point, the greenhouse gas emissions (kt of CO2 equivalent) growth rate increase 0.003 percentage points. Finally, for Spain and Italy, it is the greenhouse gas emissions that cause the burnt area.