Non-linear responses of the stratosphere and the European climate to global warming

The effects of global warming are experienced in terms of changes in meteorological phenomena, such as the storms that reach Europe, from their region of origin in the western North Atlantic. Dr Elisa Manzini and Dr Luis Kornblueh from the Max Planck Institute for Meteorology (MPI-M), and Dr Alexey Y. Karpechko from the Finnish Meteorological Institute have investigated how the atmospheric circulation changes for consecutive periods of global warming of 2 K. They found out that the atmospheric response does not scale linearly with global warming.

In their recent study, the scientists examine changes of the stratospheric polar vortex and of near-surface circulation and how both may be linked. The response of the northern winter atmospheric circulation for two consecutive global warming periods of 2 K is examined in a grand ensemble (68 members) of idealized CO2 increase experiments performed with the Max Planck Institute for Meteorology Earth System Model at Low Resolution (MPI-ESM-LR) for the prediction of the atmospheric response to an idealized scenario of global warming. Analysing the changes for an initial 2K warming and a follow-up 2-K warming provides answers to the questions if circulation changes are linear with increasing global warming and if patterns of changes scale with global warming.

The comparison of the atmospheric responses for the two periods shows remarkable differences, indicating the nonlinearity of the response. The stratospheric vortex response shifts from an easterly wind change for the first 2 K to a westerly wind change for the second 2 K. The North Atlantic storm track shifts poleward only in the second period. A weaker November Arctic amplification during the second period suggests that differences in Arctic sea ice changes can act to trigger the atmospheric nonlinear response. Stratosphere-troposphere coupling thereafter can provide for the persistence of this nonlinearity throughout the winter.

Original publication:
Manzini, E., Karpechko, A. Y., & Kornblueh, L. (2018). Nonlinear response of the stratosphere and the North Atlantic-European climate to global warming. Geophysical Research Letters, 45. Doi: 2018GL077826

More information:
Grand Ensemble

Dr Elisa Manzini
Max Planck Institute for Meteorology
Phone: +49 (0) 40 41173 317
Email: elisa.manzini@we dont want