Climate-driven Mediterranean fire hazard assessments for 2020-2100 on the light of past millennial variability

In the Mediterranean basin, Corsica (French island) harbours among the best-preserved Mediterranean forest ecosystems. However, its high biodiversity could be threatened by the climate and disturbance-regime changes due to the global warming. This study aims (i) to estimate the future climate-related fire hazard in Corsica for the current century (2020-2100) based on two RCP scenarios (RCP4.5 and RCP8.5) and (ii) to compare the predicted trends with the entire Holocene period for which fire hazard has previously been assessed. An ensemble of future climate simulations from two IPCC RCP scenarios has been used to compute the Monthly Drought Code (MDC) and the Fire Season Length (FSL) and to assess the level of fire hazard. Here, we show that the MDC and the FSL would both strongly increase over the next decades due to the combined effect of temperature increase and precipitation decrease in the Corsica region. Moreover, the maximum Holocene FLS (7000 to 9000 years ago) will be reached (and even exceeded depending upon the scenario) after 2040. For the first time in the Holocene, we may be confronted to an increase in the number of fire-prone months driven by climate combined with many human-caused ignitions. This combination should increase the burned area from 15 to 140% according to scenarios. For the next 30 years, the game seems to be already played as both RCP scenarios resulted in similar increase in fire hazard in terms of drought and duration. It is thus mandatory to reconsider fire-management and fire-prevention policy to mitigate the future fire risk and its catastrophic consequences for ecosystems, population, and economy.