Kai Kornhuber, Scott Osprey, Dim Coumou, Stefan Petri, Vladimir Petoukhov, Stefan Rahmstorf, Lesley Gray

Environmental Research Letters

Published date April 26, 2019

Extreme weather events in early summer 2018 connected by a recurrent hemispheric wave-7 pattern

Our study shows that the specific locations and timing of the 2018 summer extremes weren't random but directly connected to the emergence of a re-occurring pattern in the jet stream that stretches around the entire Northern Hemisphere.

Kai Kornhuber, lead author of the study

  • The summer of 2018 witnessed a number of extreme weather events such as heatwaves in North America, Western Europe and the Caspian Sea region, and rainfall extremes in South-East Europe and Japan that occurred near-simultaneously
  • Shows that some of these extremes were connected by an amplified hemisphere-wide wavenumber 7 circulation pattern
  • Shows that this pattern constitutes an important teleconnection in Northern Hemisphere summer associated with prolonged and above-normal temperatures in North America, Western Europe and the Caspian Sea region
  • Finds that this pattern was also observed during the European heatwaves of 2003, 2006 and 2015 among others
  • Shows that the occurrence of this wave 7 pattern has increased over recent decades