Increases in air temperature lead to increased dryness of the air and potentially develops increased dryness in the soil. Extreme dryness (in the soil and/or in the atmosphere) affects the capacity of ecosystems for functioning and for modulating the climate. Here, we used long-term high temporal resolution (daily) soil moisture (SM) and vapor pressure deficit (VPD) data of high spatial resolution (∼0.1° × 0.1°) to show that compared to the reference period (1950–1990), the overall frequency of extreme soil dryness, extreme air dryness, and extreme compound dryness (i.e., co-occurrence of extreme soil dryness and air dryness) has increased by 1.2-fold [0.8,1.6] (median [10,90 percentile], 1.6-fold [1,2.3], and 1.7-fold [0.9,2.5], respectively, over the last 31 years (1991–2021) across Europe. Our results also indicate that this increase in frequency of extreme compound dryness (between reference and 1991–2021 period) is largely due to increased SM-VPD coupling across Northern Europe, and due to decreasing SM and/or increasing VPD trend across Central and Mediterranean Europe. Furthermore, under the RCP8.5 (Representative Concentration Pathways 8.5) emission scenario, this increase in frequency of extreme compound dryness would be 3.3-fold [2.0,5.8], and 4.6-fold [2.3,11.9] by mid-21 century (2031–2065) and late-21 century (2066–2100), respectively. Additionally, we segregated the changes in frequency of extreme dryness across the most recent (year 2021) land cover types in Europe to show that croplands, broadleaved forest, and urban areas have experienced more than twice as much extreme dryness during 1990–2021 compared to the reference period of 1990–2021, which based on the future projection data will increase to more than three-fold by mid 21 century. Such future climate-change induced increase in extreme dryness could have negative implications for functioning of ecosystems and compromise their capacity to adapt to rapidly rising dryness levels.

中文翻译：

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到 21 世纪末，整个欧洲的复合土壤和空气干燥度将增加三倍以上

气温升高会导致空气更加干燥，并可能导致土壤更加干燥。极端干燥（土壤和/或大气）会影响生态系统的功能和调节气候的能力。在这里，我们使用高空间分辨率（∼0.1°×0.1°）的长期高时间分辨率（每日）土壤湿度（SM）和蒸气压赤字（VPD）数据来表明与参考期（1950-1990年）相比），极端土壤干燥、极端空气干燥和极端复合干燥（即极端土壤干燥和空气干燥同时出现）的总体频率增加了 1.2 倍 [0.8,1.6]（中位数 [10,90 百分位数]、1.6 倍 [1,2.3] 和 1.7 倍 [0.9,2.5]，分别是过去 31 年（1991-2021）欧洲各地的情况。我们的结果还表明，极端复合干旱的频率增加（参考值和 1991-2021 年期间之间的差异）主要是由于整个北欧的 SM-VPD 耦合增加，以及中欧和地中海欧洲的 SM 减少和/或 VPD 趋势增加。此外，根据 RCP8.5（代表性浓度路径 8.5） ）排放情景下，到 21 世纪中叶（2031-2065 年）和 21 世纪末（2066- 2100），分别。此外，我们对欧洲最近（2021 年）土地覆盖类型的极端干旱频率变化进行了分类，结果表明，1990 年至 2021 年期间农田、阔叶林和城市地区经历的极端干旱程度是 2021 年的两倍多。以1990年至2021年为参考期，根据未来的预测数据，到21世纪中叶，这一数字将增加到三倍以上。未来气候变化导致极端干旱的增加可能会对生态系统的功能产生负面影响，并损害其适应快速上升的干旱水平的能力。