Reduced European aerosol emissions suppress winter extremes over northern Eurasia

Winter extreme weather events receive major public attention due to their serious impacts[1], but the dominant factors regulating their interdecadal trends have not been clearly established[2,3]. Here we show that the radiative forcing due to geospatially redistributed anthropogenic aerosols mainly determined the spatial variations of winter extreme weather in the northern hemisphere during 1970-2005, a unique transition period for global aerosol forcing[4]. Over this period, the local Rossby wave activity and extreme events (top 10% in wave amplitude) exhibited marked declining trends at high latitudes, mainly in northern Eurasia. The combination of long-term observational data and a state-of-the-art climate model reveals the unambiguous signature of anthropogenic aerosols on the wintertime jet stream, planetary wave activity, and surface temperature variability on inter-decadal timescales. In particular, warming due to aerosol reductions in Europe enhances the meridional temperature gradient on the jet’s poleward flank and strengthens the zonal wind, resulting in a significant suppression in extreme events over Northern Eurasia. These results exemplify how aerosol forcing can impact large-scale extratropical atmospheric dynamics and illustrate the importance of anthropogenic aerosols and their spatiotemporal variability in assessing the drivers of extreme weather in historical and future climate.