24th Pacific Science Congress (PSC-24)

Winter warming (WW) over Northern Eurasia has been observed and modeled after major tropical volcanic eruptions, though recent studies suggest this response may be masked by internal climate variability. Here, we provide the first evidence that a high-latitude volcanic eruption can also trigger WW, using the 1783 Icelandic Laki eruption as a case study. We show that its persistent stratospheric volcanic cloud from summer to early winter and the resulting mid-latitude stratospheric warming play a key role in driving this effect. Our climate model simulations, incorporating updated volcanic forcing for the Laki eruption, closely align with two recent temperature reconstructions—whereas model simulations of other eruptions lacking substantial cold-season aerosol loadings fail to produce WW. The abnormal stratospheric warming strengthens the meridional temperature gradient, enhances the polar vortex, and shifts both horizontal and vertical energy redistribution, ultimately leading to WW. These findings help resolve discrepancies between model simulations and observational reconstructions of post-eruption winter climate responses. They also highlight the crucial role of stratosphere-troposphere coupling in shaping large-scale circulation patterns in the aftermath of volcanic eruptions.

Laki volcanic eruption;,winter warming,CESM,stratosphere-troposphere coupling