23 Aug 2022
23 Aug 2022

The extremely hot and dry 2018 summer in central and northern Europe from a multi-faceted weather and climate perspective

Efi Rousi1, Andreas H. Fink2, Lauren S. Andersen1, Florian N. Becker2, Goratz Beobide-Arsuaga3,4, Marcus Breil2,5, Giacomo Cozzi6,7, Jens Heinke1, Lisa Jach8, Deborah Niermann9, Dragan Petrovic10, Andy Richling11, Johannes Riebold12, Stella Steidl9, Laura Suarez-Gutierrez13, Jordis Tradowsky6,14, Dim Coumou1,15,16, André Düsterhus17, Florian Ellsäßer18, Georgios Fragkoulidis19, Daniel Gliksman20,21, Dörthe Handorf12, Karsten Haustein22,a, Kai Kornhuber1,23,24, Harald Kunstmann7,10, Joaquim G. Pinto2, Kirsten Warrach-Sagi8, and Elena Xoplaki18,25 Efi Rousi et al.
  • 1Potsdam Institute of Climate Impact Research (PIK), Member of the Leibniz Association, Potsdam, Germany
  • 2Institute of Meteorology and Climate Research (IMK-TRO), Karlsruhe Institute of Technology, Karlsruhe, Germany
  • 3International Max Planck Research School on Earth System Modelling (IMPRS-ESM), Germany
  • 4Institute of Oceanography, Center for Earth System Sustainability, Hamburg University, Hamburg, Germany
  • 5University of Hohenheim, Hohenheim, Germany
  • 6Deutscher Wetterdienst, Regionales Klimabüro Potsdam, Stahnsdorf, Germany
  • 7University of Augsburg, Augsburg, Germany
  • 8University of Hohenheim, Hohenheim, Germany
  • 9Deutscher Wetterdienst, Offenbach, Germany
  • 10Institute of Meteorology and Climate Research (IMK-IFU), Karlsruhe Institute of Technology, Campus Alpin, Garmisch-Partenkirchen, Germany
  • 11Institute of Meteorology, Free University of Berlin, Berlin, Germany
  • 12Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Potsdam, Germany
  • 13Max-Planck-Institut für Meteorologie, Hamburg, Germany
  • 14Bodeker Scientific, Alexandra, New Zealand
  • 15IVM-Institute for Environmental Studies, Free University of Amsterdam, Amsterdam, Netherlands
  • 16Royal Netherlands Meteorological Institute (KNMI), De Bilt, Netherlands
  • 17Irish Climate Analysis and Research UnitS (ICARUS), Department of Geography, Maynooth University, Maynooth, Ireland
  • 18Centre of International Development and Environmental Research, Justus Liebig University Giessen, Giessen, Germany
  • 19Institute for Atmospheric Physics, Johannes Gutenberg University, Mainz, Germany
  • 20Institute for Hydrology and Meteorology, Faculty of Environmental Sciences, Technische Universität Dresden, Tharandt, Germany
  • 21Institute of Geography, Technische Universität Dresden, Dresden, Germany
  • 22Climate Service Center Germany (GERICS), Helmholtz-Zentrum hereon, Hamburg, Germany
  • 23Lamont-Doherty Earth observatory, Columbia University, New York, US
  • 24German Council on Foreign Relations, Berlin, Germany
  • 25Institute of Geography, Justus Liebig University Giessen, Giessen, Germany
  • anow at: Institute for Meteorology, University of Leipzig, Leipzig, Germany

Abstract. The summer of 2018 was an extraordinary season in climatological terms for northern and central Europe, bringing simultaneous, widespread, and concurrent heat and drought extremes in large parts of the continent with extensive impacts on agriculture, forests, water supply, and socio-economic sector. We present a comprehensive, multi-faceted analysis of the 2018 extreme summer in terms of heat and drought in central and northern Europe with a particular focus on Germany. The heatwave first affected Scandinavia by mid-July, shifted towards central Europe in late July, while Iberia was primarily affected in early August. The atmospheric circulation was characterized by strongly positive blocking anomalies over Europe, in combination with a positive summer North Atlantic Oscillation and a double jet stream configuration before the initiation of the heatwave. In terms of possible precursors common to previous European heatwaves, the Eurasian double jet structure and a tripolar sea-surface temperature anomaly over the North Atlantic were identified already in spring. While in the early stages over Scandinavia the air masses at mid- and upper-levels were often of remote, maritime origin, at later stages over Iberia the air masses had primarily a local to regional origin. The drought affected Germany the most, starting with warmer than average conditions in spring, associated with enhanced latent heat release that initiated a severe depletion of soil moisture. During summer, a continued precipitation deficit exacerbated the problem, leading to hydrological and agricultural drought. A probabilistic attribution assessment of the heatwave in Germany showed that the prolonged heat has become more likely due to global warming. Regarding future projections, an extreme summer such as this of 2018 is expected to occur every two out of three years in Europe under a 1.5 °C warmer world and virtually every single year under 2 °C of global warming. With such large-scale and impactful extreme events becoming more frequent and intense under anthropogenic climate change, comprehensive and multi-faceted studies like the one presented here quantify the multitude of effects and provide valuable information as basis for adaptation and mitigation strategies.

Efi Rousi et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2022-813', Anonymous Referee #1, 16 Sep 2022
  • RC2: 'Comment on egusphere-2022-813', Anonymous Referee #2, 13 Dec 2022

Efi Rousi et al.

Efi Rousi et al.


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Short summary
Here, we present a comprehensive, multi-faceted analysis of the 2018 extreme summer in terms of heat and drought in central and northern Europe with a particular focus on Germany. Using different analysis approaches we study (a) the extremeness and attribution to anthropogenic climate change (climate perspective), as well as (b) the synoptic dynamics in concert with the role of slowly varying boundary conditions at the ocean and continental surfaces (seasonal and weather perspective).