Internal Variability Dominates the Spatial Heterogeneity of Recent Trends in Eurasian Winter Cold Extremes

Eurasia, with its large and climate-vulnerable population, has experienced increased cold extremes despite global warming, yet their pronounced spatial heterogeneity remains poorly understood. We examine low-frequency trends in Eurasian cold extremes over recent decades. Results reveal a marked zonal asymmetry, with strengthening and increasing of cold extremes over central Eurasia and weakening and decreasing of cold extremes at higher and lower latitudes. A quantitative decomposition shows that the cooling is driven primarily by internal variability rather than external forcing. The zonal asymmetry in trends is strongly associated with multidecadal variability in both the Pacific and Atlantic basins. Particularly, in the cooling region, the Atlantic-related dynamical response appears to outweigh its thermodynamic effect. Future responses, evolving through to the end of the twenty-first century, are scenario dependent: cold extremes expand under low-to-moderate emissions but decline under high emissions, as forced warming overwhelms the effect of internal variability in the far future.