In 2018, central and northern parts of Europe experienced heat and drought conditions over many months from spring to autumn, strongly affecting both natural ecosystems and crops. Besides their impact on nature and society, events like this can be used to study the impact of climate variations on the terrestrial carbon cycle, which is an important determinant of the future climate trajectory. Here, variations in the regional net ecosystem exchange (NEE) of CO₂ between terrestrial ecosystems and the atmosphere were quantified from measurements of atmospheric CO₂ mole fractions. Over Europe, several observational records have been maintained since at least 1999, giving us the opportunity to assess the 2018 anomaly in the context of at least two decades of variations, including the strong climate anomaly in 2003. In addition to an atmospheric inversion with temporally explicitly estimated anomalies, we use an inversion based on empirical statistical relations between anomalies in the local NEE and anomalies in local climate conditions. For our analysis period 1999–2018, we find that higher-than-usual NEE in hot and dry summers may tend to arise in Central Europe from enhanced ecosystem respiration due to the elevated temperatures, and in Southern Europe from reduced photosynthesis due to the reduced water availability. Despite concerns in the literature, the level of agreement between regression-based NEE anomalies and temporally explicitly estimated anomalies indicates that the atmospheric CO₂ measurements from the relatively dense European station network do provide information about the year-to-year variations of Europe’s carbon sources and sinks, at least in summer.

This article is part of the theme issue ‘Impacts of the 2018 severe drought and heatwave in Europe: from site to continental scale’.

2018年，从春季到秋季，欧洲中部和北部地区经历了数月的高温和干旱，严重影响了自然生态系统和农作物。除了它们对自然和社会的影响外，类似的事件还可以用来研究气候变化对陆地碳循环的影响，这是未来气候轨迹的重要决定因素。在此，从大气CO _2的测量值量化了陆地生态系统与大气之间CO ₂的区域净生态系统交换（NEE）的变化。摩尔分数。在欧洲范围内，至少自1999年以来一直保持着一些观测记录，这使我们有机会在至少两十年的变化背景下评估2018年的异常，包括2003年的强烈气候异常。显式估计的异常，我们使用基于当地NEE异常与当地气候条件异常之间经验统计关系的反演。在我们的1999-2018年分析期间，我们发现，中高温地区由于高温导致生态系统呼吸增强，而在炎热干燥的夏季可能会出现高于正常水平的NEE；而南欧地区由于温度降低而导致的光合作用降低，可能会产生高于常规水平的NEE。可用水量。尽管有文献关注，至少在夏季，来自相对密集的欧洲站点网络的_2次测量确实提供了有关欧洲碳源和汇的年度变化的信息。

本文是主题问题``欧洲2018年严重干旱和热浪的影响：从站点到大陆范围的影响''的一部分。