Abstract
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'.
Highlights
In the last two decades, Europe has been affected by extreme summer drought and heat (DH) events, each characterized by record-breaking climate anomalies and large associated economic, social and environmental costs [1,2,3]
DH2018 affected higher latitude and less drought-prone regions compared to DH2003, which was centred in western Europe, including Mediterranean ecosystems [1]
We have compared the impacts of the three extreme summers in the past two decades on European ecosystems’ CO2 uptake
Summary
In the last two decades, Europe has been affected by extreme summer drought and heat (DH) events, each characterized by record-breaking climate anomalies and large associated economic, social and environmental costs [1,2,3]. Both the 2003 and 2010 extreme summers in western Europe and western Russia, respectively, were caused by a combination of atmospheric circulation anomalies and landatmosphere feedbacks [4,5,6], on top of anthropogenic climate change [7]. In 2018, the extreme warm and sunny conditions in spring and concurrent increase in evapotranspiration have contributed significantly to amplify the summer drought
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