Quantifying the current and future likelihood of the 2022 extreme wildfires weather conditions in France with anthropogenic climate change

Abstract. In 2022, southwestern France experienced an exceptional wildfire season, recording a burned area 14 times higher than the 2006–2023 average. Here, we assess the rarity of the fire weather conditions observed in 2022 and how anthropogenic climate change (ACC) has already altered and will continue to alter the probability of fire weather conditions associated with the three largest wildfires (Landiras-1: 12,552 ha; Landiras-2: 7,124 ha; La Teste-de-Buch: 5,709 ha). Drawing from the daily Fire Weather Index (FWI) computed from two reanalysis datasets (1959–2023) and a nationwide wildfire record dataset (2006–2023), we first sought to quantify the rarity of those conditions across a range of spatial (fire location versus regional) and temporal (fire duration versus monthly) scales. Our results show that the extremeness of FWI conditions generally increases with the spatiotemporal resolution, with the associated return periods increasing from 6 to 34 years, from 22 to 89 years, and from 6 to 101 years when moving from the coarsest to the finest spatiotemporal scale for the Landiras-1, Landiras-2, and La Teste-de-Buch wildfires, respectively. Using climate simulations from the Coupled Model Intercomparison Project Phase 6 (CMIP6), we examined how ACC has modified the probability of such fire weather conditions between 1950 and 2100. We found that by 2022, ACC at least doubled the likelihood of those FWI conditions, and will make them, by the end of the century (under the Shared Socioeconomic Pathway 2-4.5, (SSP2-4.5)) at least 10–100 times more probable, depending on the models. Our study underlines the growing influence of ACC in the risk of extreme wildfires in France across a range of scales.