In Europe, three widespread extreme summer drought and heat (DH) events have occurred in 2003, 2010 and 2018. These events were comparable in magnitude but varied in their geographical distribution and biomes affected. In this study, we perform a comparative analysis of the impact of the DH events on ecosystem CO₂ fluxes over Europe based on an ensemble of 11 dynamic global vegetation models (DGVMs), and the observation-based FLUXCOM product. We find that all DH events were associated with decreases in net ecosystem productivity (NEP), but the gross summer flux anomalies differ between DGVMs and FLUXCOM. At the annual scale, FLUXCOM and DGVMs indicate close to neutral or above-average land CO₂ uptake in DH2003 and DH2018, due to increased productivity in spring and reduced respiration in autumn and winter compensating for less photosynthetic uptake in summer. Most DGVMs estimate lower gross primary production (GPP) sensitivity to soil moisture during extreme summers than FLUXCOM. Finally, we show that the different impacts of the DH events at continental-scale GPP are in part related to differences in vegetation composition of the regions affected and to regional compensating or offsetting effects from climate anomalies beyond the DH centres.

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

在欧洲，2003 年、2010 年和 2018 年发生了 3 次广泛的夏季极端干旱和炎热 (DH) 事件。 这些事件的规模相当，但其地理分布和受影响的生物群落各不相同。在本研究中，我们基于 11 个动态全球植被模型 (DGVM) 和基于观测的 FLUXCOM 产品，对 DH 事件对欧洲生态系统 CO ₂通量的影响进行了比较分析。我们发现所有 DH 事件都与净生态系统生产力 (NEP) 的下降有关，但 DGVM 和 FLUXCOM 之间的夏季总通量异常不同。在年度尺度上，FLUXCOM 和 DGVM 表明接近中性或高于平均水平的土地 CO ₂DH2003 和 DH2018 的吸收量增加，原因是春季生产力增加，秋季和冬季呼吸减少，弥补了夏季光合吸收量的减少。大多数 DGVM 估计在极端夏季对土壤水分的总初级生产 (GPP) 敏感性低于 FLUXCOM。最后，我们表明大陆尺度 GPP DH 事件的不同影响部分与受影响区域的植被组成差异以及 DH 中心以外气候异常的区域补偿或抵消效应有关。

本文是主题问题“2018 年欧洲严重干旱和热浪的影响：从场地到大陆尺度”的一部分。