Preprints
https://doi.org/10.5194/egusphere-2022-954
https://doi.org/10.5194/egusphere-2022-954
 
06 Oct 2022
06 Oct 2022
Status: this preprint is open for discussion.

The 2018 west-central European drought projected in a warmer climate: how much drier can it get?

Emma Elizabeth Aalbers1,2, Erik van Meijgaard1, Geert Lenderink1, Hylke de Vries1, and Bart J. J. M. van den Hurk2,3 Emma Elizabeth Aalbers et al.
  • 1Royal Netherlands Meteorological Institute (KNMI), PO Box 201, 3730 AE, De Bilt, Netherlands
  • 2Institute for Environmental Studies (IVM), VU University Amsterdam, Netherlands
  • 3Deltares, Delft, The Netherlands

Abstract. Projections of changes in extreme droughts under future climate conditions are associated with large uncertainties, owing to the complex genesis of droughts and large model uncertainty in the atmospheric dynamics. In this study we investigate the impact of global warming on soil moisture drought severity in west-central Europe by employing pseudo-global warming (PGW) experiments, which project the 1980–2020 period in a globally warmer world. The future analogues of present-day drought episodes allow investigation of changes in drought severity conditional on the historic day-to-day evolution of the atmospheric circulation.

The 2018 west-central European drought is the most severe drought in the 1980–2020 reference period in this region. Under 1.5 °C, 2 °C and 3 °C global warming, this drought episode experiences strongly enhanced summer temperatures, but a fairly modest soil moisture drying response compared to the change in climatology. This is primarily because evaporation is already strongly moisture-constrained during present-day conditions, limiting the increase in evaporation and thus the modulation of the temperature response under PGW. Increasing precipitation in winter, spring and autumn limit or prevent an earlier drought onset and duration. Nevertheless, the drought severity, defined as the cumulative soil moisture deficit volume, increases considerably, with 20 % to 39 % under 2 °C warming.

The extreme drought frequency in the 1980–2020 period strongly increases under 2 °C warming. Several years without noticeable droughts under present-day conditions show very strong drying and warming. This results in an increase in 2003-like drought occurrences, compounding with local summer temperature increases considerably above 2 °C.

Even without taking into account a (potentially large) dynamical response to climate change, drought risk in west-central Europe is strongly enhanced under global warming. Owing to increases in drought frequency, severity and compounding heat, a reduction in recovery times between drought episodes is expected to occur. Our physical climate storyline provides evidence complementing conventional large-ensemble approaches, and is intended to contribute to the formulation of effective adaptation strategies.

Emma Elizabeth Aalbers et al.

Status: open (until 14 Dec 2022)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2022-954', Patrick Ludwig, 16 Nov 2022 reply
  • RC2: 'Comment on egusphere-2022-954', Linda van Garderen, 22 Nov 2022 reply

Emma Elizabeth Aalbers et al.

Emma Elizabeth Aalbers et al.

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Short summary
To examine the impact of global warming on west-central European droughts, we have constructed future analogues of recent summers. Years that went hardly noticed in the present-day climate may emerge as very dry and hot in a warmer world. Extreme droughts like 2018 further intensify and the local temperature rise is much larger than in most summers. These changes can be directly linked to real world events, which make the results very tangible and hence useful for climate change communication.