The co-occurrence of warm spells and droughts can lead to detrimental socio-economic and ecological impacts, largely surpassing the impacts of either warm spells or droughts alone. We quantify changes in the number of compound warm spells and droughts from 1979 to 2018 in the Mediterranean Basin using the ERA5 data set. We analyse two types of compound events: 1) warm season compound events, which are extreme in absolute terms in the warm season from May to October and 2) year-round deseasonalised compound events, which are extreme in relative terms respective to the time of the year. The number of compound events increases significantly and especially warm spells are increasing strongly – with an annual growth rates of 3.9 (3.5) % for warm season (deseasonalised) compound events and 4.6 (4.4) % for warm spells –, whereas for droughts the change is more ambiguous depending on the applied definition. Therefore, the rise in the number of compound events is primarily driven by temperature changes and not the lack of precipitation. The months July and August show the highest increases in warm season compound events, whereas the highest increases of deseasonalised compound events occur in spring and early summer. This increase in deseasonalised compound events can potentially have a significant impact on the functioning of Mediterranean ecosystems as this is the peak phase of ecosystem productivity and a vital phenophase.

温暖的季节和干旱并存会导致有害的社会经济和生态影响，大大超过了温暖的季节或干旱的影响。我们使用ERA5数据集量化了1979年至2018年地中海盆地复合暖期和干旱数量的变化。我们分析了两种类型的复合事件：1）暖季复合事件，在从五月到十月的暖季中，绝对值是绝对的； 2）全年淡季复合事件，相对于时间而言是相对极端的。那一年。复合事件的数量显着增加，尤其是暖场的增长迅速-暖季（淡季）复合事件的年增长率为3.9（3.5）％，暖场的年增长率为4.6（4.4）％– 而对于干旱，根据所应用的定义，变化更为模糊。因此，复合事件数量的增加主要是由温度变化而不是缺乏降水驱动。7月和8月这两个月份显示出暖季复合事件的增幅最大，而反季节复合事件的增幅最大出现在春季和初夏。季节性减少的复合事件的增加可能会对地中海生态系统的功能产生重大影响，因为这是生态系统生产力的高峰期和重要的现象期。7月和8月这两个月份显示出暖季复合事件的增幅最大，而反季节复合事件的增幅最大出现在春季和初夏。季节性减少的复合事件的增加可能会对地中海生态系统的功能产生重大影响，因为这是生态系统生产力的高峰期和重要的现象期。7月和8月这两个月份显示出暖季复合事件的增幅最大，而反季节复合事件的增幅最大出现在春季和初夏。季节性减少的复合事件的增加可能会对地中海生态系统的功能产生重大影响，因为这是生态系统生产力的高峰期和重要的现象期。