Comment on essd-2022-413

Abstract

<strong class="journal-contentHeaderColor">Abstract.</strong> Human-induced climate change is increasing the incidence of fire events and associated impacts on livelihood, biodiversity, and nature across the world. Understanding current and projected fire activity together with its impacts on ecosystems is crucial to evaluate future risks and take actions to prevent such devastating events. Here we focus on fire weather, as a key driver of fire activity. Fire weather products that have global homogenous distribution in time and space provide many advantages to advance fire science and evaluate future risks. Therefore, in this study we calculate the Canadian Fire Weather Index (FWI) with all available simulations of the 6th phase of the Coupled Model Intercomparison Project (CMIP6). The algorithm used here assembles improvements from several packages for the calculation of the FWI. A sensitivity analysis of the default versus the improved version shows significant differences in final FWI. With the improved version, we calculate the FWI using average relative humidity in one case and minimum relative humidity in another case. We provide the data for both cases, while recommending the one with average relative humidity for studies requiring large ensembles and the one with minimum relative humidity for studies focused on actual FWI values. The following four annual indicators: (i) maximum value of the FWI (fwixx), (ii) number of days with extreme fire weather (<em>fwixd</em>), (iii) length of the fire season (<em>fwils</em>), and (iv) seasonal average of the FWI (<em>fwisa</em>) are made available and illustrated here. We find that at a global warming level of 3 &deg;C, the mean fire weather would on average double in duration and intensity, while associated 1-in-10-year events would triple in duration and increase by half in intensity. Ultimately, this new fire weather dataset provides a large ensemble of simulations to understand the potential impacts of climate change spanning a range of shared socioeconomic narratives with their radiative forcing trajectories. The produced full global dataset is a freely available resource at <a href="https://doi.org/10.3929/ethz-b-000583391" target="_blank" rel="noopener">https://doi.org/10.3929/ethz-b-000583391</a> for fire danger studies and beyond, which highlights the need to reduce greenhouse gas emissions for reducing fire impacts.