Comment on nhess-2023-51

Abstract

<strong class="journal-contentHeaderColor">Abstract.</strong> Wildfires have reached an unprecedented scale in the Northern Hemisphere. The summers of 2021 and 2022 demonstrated the destructive power of wildfires especially in Northern America and Southern Europe. Global warming indicates that fire seasons will become more extreme and will extend to more temperate regions in northern latitudes in the future. Multiple studies claim that natural variability hides the trend of increasing fire danger in climate model simulations for future potentially fire-prone areas. Single Model Initial-Condition Large Ensembles (SMILEs) help scientists to distinguish climate trends from natural variability. So far, the SMILE framework has only been applied for fire danger estimation on a global scale. In this study, we use a regional SMILE of the Canadian regional climate model version 5 (CRCM5-LE) over Central Europe under the RCP 8.5 scenario from 1980 to 2099, to analyze fire danger trends in a currently not fire-prone area. We use the meteorological Canadian Fire Weather Index (FWI) as a fire danger indicator. The study area covers four heterogeneous landscapes, namely the Alps, the Alpine Foreland, the lowlands of the Southern German Escarpment and the Eastern Mountain Ranges of the Bavarian Forest. We demonstrate that the CRCM5-LE is a suitable dataset to disentangle climate trends from natural variability in a multivariate fire danger metric. Results show the strongest increases in the median (50^th) and extreme (90^th) percentile of the FWI in the northern parts of the study area in the summer months July and August, where high fire danger becomes the median condition and extremes occur earlier in the fire season. The southern parts of the study region are affected less strongly, but due to weaker variability in these regions, time of emergence (TOE) is reached there in the early 2040&rsquo;s. In the northern parts, the climate change trend exceeds natural variability in the late 2040&rsquo;s. We find that today&rsquo;s threshold for a 100-year FWI event, will occur every 30 years by 2050 and every 10 years by 2099. Our results highlight Central Europe&rsquo;s potential for severe fire events from a meteorological perspective and the need for fire management in the near future even in temperate regions.