Unravelling the Effect of Climate Change on Fire Danger and Fire Behaviour in the Transboundary Biosphere Reserve of Meseta Ibérica (Portugal-Spain)

Abstract The impacts of wildfires are increasing in the Mediterranean Basin due to more extreme fire seasons that often overwhelm the response capacity of fire suppression forces. In this study, we quantified the effect of climate change on fire danger (components of the Canadian FWI System) and wildfire behaviour characteristics (rate of spread and fireline intensity) for the four major Mediterranean forest ecosystems in the transboundary biosphere reserve of the Meseta Ibérica under RCP4.5 and RCP8.5 scenarios. The effect of climate change on wildfire behaviour was also complemented by considering changes in net primary production (NPP), and hence available fuel. Our results show that the meteorological fire season will start earlier and end later, leading to a significant increase in the number of days with weather conditions that promote large wildfires. For fire behaviour, the most relevant changes will occur in pine forests, where a wildfire with median fireline intensity will offer serious resistance to control from spring to autumn. The severity of fire behaviour in shrublands also increases substantially when considering climate change, with high-intensity wildfires potentially occurring in any time of the year. Both deciduous and evergreen broadleaves forests are predicted to typically generate wildfires that remain within suppression capability. By adjusting NPP to future climate conditions, the fireline intensity may not increase during summer in deciduous and evergreen broadleaves forests, and can even be significantly reduced in shrublands. This study suggests that improved fire planning and management of wildfire-prone landscapes will counteract the effect of climate change on fire behaviour and impacts.