Abstract. 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 for evaluating future risks and taking actions to prevent such devastating events. Here we focus on fire weather as a key driver of fire activity. Fire weather products that have a global homogenous distribution in time and space provide many advantages to advance fire science and evaluate future risks. Therefore, in this study we calculate and provide for the first time the Canadian Fire Weather Index (FWI) with all available simulations of the 6th phase of the Coupled Model Intercomparison Project (CMIP6). Furthermore, we expand its regional applicability by combining improvements to the original algorithm for the FWI from several packages. A sensitivity analysis of the default version versus our improved version shows significant differences in the 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 minimum relative humidity for studies focused on actual FWI values and the one with average relative humidity for studies requiring larger ensembles. The following four annual indicators, (i) maximum value of the FWI (fwixx), (ii) number of days with extreme fire weather (fwixd), (iii) length of the fire season (fwils), and (iv) seasonal average of the FWI (fwisa), are made available and are illustrated here. We find that, at a global warming level of 3 ∘C, the mean fire weather would increase on average by at least 66 % in duration and frequency, while associated 1-in-10-year events would approximately triple in duration and increase by at least 31 % 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 over 1850–2100 at annual and 2.5∘ × 2.5∘ resolutions. The produced full global dataset is a freely available resource at https://doi.org/10.3929/ethz-b-000583391 (Quilcaille and Batibeniz, 2022) for fire danger studies and beyond, which highlights the need to reduce greenhouse gas emissions for reducing fire impacts.

中文翻译：

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1850年至2100年第六期耦合模型比对项目历史和共享社会经济路径预测下的火灾天气指数数据

摘要。人为引起的气候变化正在增加火灾事件的发生率以及对全世界生计、生物多样性和自然的相关影响。了解当前和预计的火灾活动及其对生态系统的影响对于评估未来风险和采取行动防止此类破坏性事件至关重要。在这里，我们关注火灾天气作为火灾活动的主要驱动因素。在时间和空间上具有全球均匀分布的火灾天气产品为推进火灾科学和评估未来风险提供了许多优势。因此，在本研究中，我们首次计算并提供了加拿大火灾天气指数 (FWI)，以及耦合模型比对项目 (CMIP6) 第 6 阶段的所有可用模拟。此外，我们通过结合几个软件包对 FWI 原始算法的改进来扩展其区域适用性。默认版本与我们的改进版本的敏感性分析显示最终 FWI 存在显着差异。在改进版本中，我们在一种情况下使用平均相对湿度计算 FWI，在另一种情况下使用最小相对湿度。我们提供这两种情况的数据，同时为侧重于实际 FWI 值的研究推荐具有最小相对湿度的数据，为需要更大集合的研究推荐具有平均相对湿度的数据。以下四个年度指标，(i) FWI 的最大值 (fwixx)，(ii) 极端火灾天气的天数 (fwixd)，(iii) 火灾季节的长度 (fwils)，以及 (iv) 季节平均值FWI (fwisa), 已提供并在此处进行了说明。我们发现，在 3 °C 的全球变暖水平下，平均火灾天气的持续时间和频率将平均增加至少 66%，而相关的 10 年一遇事件的持续时间将增加大约两倍，并增加强度至少为 31%。最终，这个新的火灾天气数据集提供了大量的模拟，以了解气候变化的潜在影响，涵盖一系列共享的社会经济叙事及其在 1850-2100 年和 2.5∘ × 2.5∘ 分辨率下的辐射强迫轨迹。生成的完整全球数据集是 https://doi.org/10.3929/ethz-b-000583391（Quilcaille 和 Batibeniz，2022 年）的免费资源，用于火灾危险研究及其他研究，强调减少温室气体排放的必要性减少火灾影响。