In Europe, regional climate change prospects indicate the urgency of adapting to extreme weather events. While increasing temperature trends have already been detected, in the last decades, the adoption of a European heatwave (HW) early-warning index is not yet consensual, partially due to the significant number of alternative algorithms, in some cases adjusted to the measurement of sector-specific impacts (as per the Expert Team on Climate Risk and Sector-specific Indices (ET-SCI)). In particular, the Excess Heat Factor (EHF) has been shown to accurately predict heat-related human health outcomes, in mid-latitude climates, provided that local summer exposure to excess heat is mostly driven by extreme air temperatures, with a lower contribution from relative humidity. Here, annual summaries of EHF-based HW detection were calculated for the European region, using daily maximum and minimum temperatures from the homogenised version of the E-OBS gridded dataset. Annual HW frequencies, duration, mean magnitude, maximum amplitude, and severity were subject to climatology and trend analysis across the European biogeographical regions, considering the 1961–1990 period as the baseline reference for anomaly detection in the more recent (1991–2018) decades. As HW-dependent morbidity/mortality affects mostly the elderly, an EHF-based HW Exposure Index was also calculated, by multiplying the recent probability of severe events per the number of people aged 65, or more, in the European Functional Urban Areas (FUAs). Results show that recent historical EHF-based patterns diverge across European Biogeographical regions, with a clear latitudinal gradient. Both the historical mean and recent trends point towards the greater exposure in the southern European Mediterranean region, driven by the significant increase of HW frequency, duration and maximum severity, especially in the last 3 decades; conversely, annual maximum EHF intensities (i.e., greatest deviations from the local 90th daily mean temperature) are mostly found in the northern and/or high altitude Boreal, Alpine and Continental regions, as a consequence of the latitudinal effect of local climatology on the HWM/HWA indices (this also translates into greater magnitudes of change, in this regions). Nonetheless, by simultaneously considering the probability of Severe HW occurrence in the last three decades, together with the log transformation of people aged 65 or more, results show that greater HW Exposure Indices affect FUAs across the whole Europe, irrespective of its regional climate, suggesting that more meaningful vulnerability assessments, early warning and adaptation measures should be prioritized accordingly.

在欧洲，区域气候变化前景表明适应极端天气事件的紧迫性。虽然已经检测到温度升高的趋势，但在过去几十年中，采用欧洲热浪 (HW) 预警指数尚未达成共识，部分原因是大量替代算法，在某些情况下调整为特定部门的影响（根据气候风险和部门特定指数专家组 (ET-SCI)）。特别是，在中纬度气候条件下，过热因子 (EHF) 已被证明可以准确预测与热相关的人类健康结果，前提是当地夏季暴露于过热主要是由极端气温驱动的，而来自相对湿度。这里，使用来自 E-OBS 网格数据集的均质版本的每日最高和最低温度计算了欧洲地区基于 EHF 的硬件检测的年度总结。考虑到 1961 年至 1990 年期间作为最近（1991 年至 2018 年）几十年中异常检测的基线参考，年度 HW 频率、持续时间、平均幅度、最大幅度和严重程度受到整个欧洲生物地理区域的气候学和趋势分析的影响. 由于硬件依赖的发病率/死亡率主要影响老年人，因此还计算了基于 EHF 的硬件暴露指数，方法是将欧洲功能性城市地区 (FUA) 中每 65 岁或以上人口的近期严重事件概率相乘）。结果表明，最近基于 EHF 的历史模式在欧洲生物地理区域之间存在分歧，具有明显的纬度梯度。历史均值和近期趋势均表明南欧地中海地区的暴露量更大，这是由于 HW 频率、持续时间和最大严重程度显着增加，特别是在过去 30 年中；相反，由于当地气候对 HWM 的纬度影响，年最大 EHF 强度（即与当地第 90 天日平均温度的最大偏差）主要出现在北部和/或高海拔的北方、高山和大陆地区/HWA 指数（这也转化为该地区更大的变化幅度）。尽管如此，通过同时考虑过去 30 年发生严重 HW 的概率，以及 65 岁或以上人群的对数变换，