Surface temperatures have risen in decades,with an increasing frequency of summer heat waves over most land areas,particularly across Eurasia.This rapid warming and the intensification of extreme temperatures have significant environmental,economic,and societal impacts,making it crucial to understand the underlying causes.Observational data indicate that since the mid-1990s,summer warming has been remarkably amplified over Europe and East Asia,revealing non-uniform decadal warming rates across Eurasia.This heterogenous warming pattern may result from internal multidecadal variability—such as the Atlantic Multidecadal Oscillation (AMO)—as well as changes in anthropogenic greenhouse gases (GHGs) and aerosols.However,the relative contributions of these factors to Eurasia's summer warming patterns remain unclear.A more precise quantification of the roles played by the AMO,decadal variations in aerosol,and other external forcing mechanisms could improve our understanding of recent non-uniform warming trends.Results indicate that GHG-induced surface air temperature (SAT) increases are most pronounced over the driest regions of Eurasia and North Africa,though decadal variations in GHG-induced SAT changes are minimal.To isolate external forcing effects unrelated to the steady rise in GHGs,this study removes the GHG-induced SAT component from observations and applies an empirical orthogonal function analysis to the residuals (referred to as GHG-detrended SAT),identifying the dominant spatial and temporal characteristics of Eurasian SAT variability.The GHG-detrended SAT exhibits strong multidecadal fluctuations,with negative anomalies from the 1960s to the mid-1990s and positive anomalies during the 1950s,early 1960s and post-1990s.Between 1984 and 2014,significant warming occurred over Europe-West Asia and Central East Asia,whereas 1953—1984 saw widespread cooling.Central Asia,however,experienced only weak out-of-phase variations.The estimated internal variability component reveals a similar tripole pattern,with a pronounced negative center over Central Asia,closely correlated with GHG-detrended SAT variations.These findings confirm that the AMO is the dominant driver of multidecadal SAT variability over Eurasia.Meanwhile,the estimated externally forced component exhibits comparable multidecadal fluctuations but with consistent spatial coefficients across Eurasia.Over the period 1950—2014,externally forced changes accounted for approximately 55% of the GHG-detrended multidecadal SAT variations over Europe-West Asia and ～51% over East Asia,with the remainder attributed to internal variability.These results suggest that,contrary to previous assumptions,more than half of Eurasia's multidecadal SAT variability since 1950 has been externally forced rather than predominantly driven by internal variability.Furthermore,the primary driver of externally forced non-uniform multidecadal SAT variations is identified as anthropogenic aerosols.This study demonstrates that both external forcing and internally driven variability originating from the Atlantic Ocean have contributed to Eurasia's multidecadal SAT variations since 1950.Looking ahead,continued reductions in aerosol concentrations,the likely persistence of the AMO in its positive phase,and ongoing increases in GHGs are expected to future intensify warm-season temperatures across Europe-West Asia and East Asia in the coming decade.