A First Assessment of the 2018 European Drought Impact on Ecosystem Evapotranspiration

Kazi Rifat Ahmed,Eugénie Paul-Limoges,Uwe Rascher,Alexander Damm

doi:10.3390/rs13010016

Abstract

The combined heatwave and drought in 2018 notably affected the state and functioning of European ecosystems. The severity and distribution of this extreme event across ecosystem types and its possible implication on ecosystem water fluxes are still poorly understood. This study estimates spatio-temporal changes in evapotranspiration (ET) during the 2018 drought and heatwave and assesses how these changes are distributed in European ecosystems along climatic gradients. We used the ET eight-day composite product from the MODerate Resolution Imaging Spectroradiometer (MODIS) together with meteorological data from the European Centre for Medium-Range Weather Forecasts (ECMWF ERA5). Our results indicate that ecosystem ET was strongly reduced (up to −50% compared to a 10-year reference period) in areas with extreme anomalies in surface air temperature (Tsa) and precipitation (P) in central, northern, eastern, and western Europe. Northern and Eastern Europe had prolonged anomalies of up to seven months with extreme intensities (relative and absolute) of Tsa, P, and ET. Particularly, agricultural areas, mixed natural vegetation, and non-irrigated agricultural areas were the most affected by the increased temperatures in northern Europe. Our results show contrasting drought impacts on ecosystem ET between the North and South of Europe as well as on ecosystem types.

Highlights

Extreme climate events can substantially alter the state and integrity of ecosystems. the increased frequency and duration of such events substantially impact energy and water fluxes in ecosystems [1,2] and cause various feedbacks between the atmosphere and the biosphere [3,4]
This study showed that during the 2003 drought, especially soil drought together with a high vapor pressure deficit (VPD) determined stomatal closure and reduced gross primary production (GPP)
The aim of this study is to quantify the impact of the combined drought and heatwave in 2018 on ecosystem ET, and to assess how these changes are distributed in different ecosystem types along climatic gradients in Europe

Summary

Introduction

Extreme climate events can substantially alter the state and integrity of ecosystems. the increased frequency and duration of such events (i.e., droughts and heatwaves) substantially impact energy and water fluxes in ecosystems [1,2] and cause various feedbacks between the atmosphere and the biosphere [3,4]. A recent example is the combined European drought and heatwave of 2018 that severely affected European ecosystems, caused severe damages and substantially altered the functioning of these ecosystems [5,6]. This extreme event has been characterized as exceptionally warm, especially around its epicenter in northern and central Europe [7]. Recent studies reported a decline in ET in the past decades and observed some substantial feedback with increasing temperature and drought [9,10] These complex interplays depend on regional climatic variability and ecosystem conditions [10,11]. Other studies indicated changing ET pattern due to climate change and related drought events [1,12,13,14,15], having

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