Persistent stratospheric cold-season aerosols from the 1783 Laki eruption produced winter warming over Northern Eurasia

Northern Eurasia tropospheric winter warming has been observed and modeled after major tropical volcanic eruptions. Here we show that a high-latitude eruption with a persistent stratospheric volcanic cloud from summer to early winter can also trigger winter warming. Our model simulations, incorporating updated volcanic forcing for the 1783 Laki eruption, closely align with two recent temperature reconstructions—whereas simulations of other eruptions lacking substantial cold-season aerosol loadings fail to produce such warming. The aerosol-induced mid-latitude stratospheric warming strengthens the meridional temperature gradient, enhances the polar vortex, and shifts both horizontal and vertical energy redistribution in favor of Northern Eurasia winter warming. Neutral or cold winters, nevertheless, remain possible in individual realizations due to internal variability. These findings help resolve model-observation discrepancies and highlight the crucial role of stratosphere-troposphere coupling in shaping large-scale circulation patterns in the aftermath of volcanic eruptions. The 1783 Laki eruption triggered Northern Eurasia tropospheric winter warming due to a persistent cold-season stratospheric aerosol cloud. Climate model simulations, accounting for the multi-episode nature of the eruption, were validated by observational reconstructions of the climate response.