Global warming is leading to increased heat stress in many regions around the world. An extensive number of heat stress indicators (HSIs) has been developed to measure the associated impacts on human health. Here we calculate eight HSIs for global climate models participating in the Coupled Model Intercomparison Project Phase 6 (CMIP6). We compare their future trends as function of global mean temperature, with particular focus on highly populated regions. All analyzed HSIs increase significantly (p < 0.01) in all considered regions. Moreover, the different HSIs reveal a substantial spread ranging from trends close to the rate of global mean temperature up to an amplification of more than a factor of two. Trends change considerably when normalizing the HSIs by accounting for the different scales on which they are defined, but the large spread and strong trends remain. Consistently, exceedances of impact‐relevant thresholds are strongly increasing globally, including in several densely populated regions, but also show substantial spread across the selected HSIs. The indicators with the highest exceedance rates vary for different threshold levels, suggesting that the large indicator spread is associated both to differences in trend magnitude and the definition of threshold levels. These results highlight the importance of choosing indicators and thresholds that are appropriate for the respective impact under consideration. Additionally, further validation of HSIs regarding their capability to quantify heat impacts on human health on regional‐to‐global scales would be of great value for assessing global impacts of future heat stress more reliably.

中文翻译：

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CMIP6中的热应激指标：估计未来趋势和影响相关阈值的超出范围

全球变暖正在导致世界许多地区的热压力增加。已经开发了大量的热应激指标（HSI），以测量对人体健康的相关影响。在这里，我们为参与耦合模型比对项目第6阶段（CMIP6）的全球气候模型计算了8个HSI。我们将它们的未来趋势作为全球平均温度的函数进行比较，特别关注人口稠密的地区。所有分析的恒指均显着增加（p <0.01）。此外，不同的恒指指数显示出从接近全球平均温度的趋势到大于两倍的放大倍数的显着扩散。当通过考虑定义HSI的不同规模来对HSI进行归一化时，趋势会发生很大变化，但是仍然存在较大的传播和强劲的趋势。一致地，影响相关阈值的超出范围在全球范围内急剧增加，包括在几个人口稠密的地区，但在选定的HSI上也显示出相当大的分布。具有最高超出率的指标随阈值水平的不同而变化，这表明较大的指标价差既与趋势幅度的差异也与阈值水平的定义有关。这些结果凸显了选择适合所考虑的各个影响的指标和阈值的重要性。此外，进一步验证HSI在区域到全球范围内量化热量对人类健康的影响的能力，对于更可靠地评估未来热量压力的全球影响将具有重要的价值。