Abstract/Summary

Extreme wind speeds associated with midlatitude cyclones pose a hazard tolives, businesses and infrastructure, and thus changes in their pattern and mag-nitude have important implications under human-induced global climate change.Here, we systematically explore, at a global scale, the contribution of midlatitudecyclones to extreme wind speed events occurring in both the Northern Hemi-sphere (NH) and Southern Hemisphere (SH) under a present and an idealisedglobal warming scenario with a homogeneous SST increase of 2 K. Using theNOAA’s Geophysical Fluid Dynamics Laboratory’s new high-resolution globalclimate model, we find that extreme near-surface wind speeds intensify by upto 3% K−1towards the poles, while they decrease by up to the same amountin the lower midlatitudes. When considering only cyclone-associated extremewind speed events, the same migration towards higher latitudes is found inboth percentage per degree warming and absolute value. Although the totalnumber of midlatitude cyclones decreases by roughly 4%, the proportion ofcyclone-associated near-surface extreme wind speed events in the warmer climatesimulation compared to the present climate simulation increases by 10%. Overall,the objective attribution of extreme wind speed events to midlatitude cyclonesdemonstrates that the poleward shift of midlatitude cyclones tracks and intensityresults into a poleward migration of cyclone-associated extreme wind speeds inboth hemispheres, leading to large impacts over the inhabited areas of the NH,including North-Western Europe, the British Isles, and the West Coast of NorthAmerica.