Poleward intensification of midlatitude extreme winds under warmer climate

Abstract

Our study investigates the global impact of midlatitude cyclones on extreme wind speed events in both hemispheres under a warmer climate. Using the latest version of the high-resolution ≈ 50 km grid-spacing atmospheric climate model AM4, developed by the Geophysical Fluid Dynamics Laboratory, we conducted simulations covering the 71-years period 1949–2019 for both the present-day climate and an idealised future global warming climate scenario with a homogeneous Sea Surface Temperature (SST) increase by 2 K. Our findings reveal that extreme near-surface wind speeds increase by up to 3% K−1 towards the poles while decrease by a similar amount in the lower midlatitudes. When considering only extreme wind speed events objectively attributed to midlatitude cyclones, we observe a migration by the same amount towards higher latitudes both in percentage per degree SST warming and absolute value. The total number of midlatitude cyclones decreases by roughly 4%, but the proportion of cyclone-associated extreme wind speed events increases by 10% in a warmer climate. Finally, Northwestern Europe, the British Isles, and the West Coast of North America are identified as hot spots with the greatest socio-economic impacts from increased cyclone-associated extreme winds.