The influence of variability on fire weather conditions in high latitude regions under present and future global warming

Abstract Recent years have seen unprecedented fire activity at high latitudes and knowledge of future wildfire risk is key for adaptation management. Here we present a systematic characterization the probability distributions (PDFs) weather conditions, how it arises from underlying meteorological drivers change, in five boreal forest regions, pre-industrial conditions different global warming levels. Using initial condition ensembles two climate models to characterize regional variability, quantify PDFs daily maximum surface air temperature (SAT max ), precipitation, wind, minimum relative humidity (RH min their evolution with temperature. The resulting aggregate change quantified using Canadian Fire Weather Index (FWI). In all regions find increases both means upper tails FWI distribution, widening suggesting increased variability. main are projected increase mean SAT decline RH , marked already +1 +2 °C warming. largest changes occur Canada, where estimate doubling days moderate-or-higher between +4 warming, smallest Alaska. While exhibit same general features differences magnitude shifts exist, particularly bias compared reanalysis also largest. Given its importance FWI, identified as an area need further research. occurrence severity wildfires ultimately depend on factors such ignition fuel, show improved conducive risk, changing across latitudes, can be used first indication near-term changes. Our results confirm that continued rapidly push into increasingly unfamiliar regimes.