Attribution of multidecadal summer temperature variations over Eurasia

Abstract Surface air temperature (SAT) over Eurasia exhibits a non-uniform pattern during summer, with pronounced warming over Europe and East Asia. However, the contributions of thermodynamic and dynamic processes resulting from internal climate variability and external forcing to the non-uniform warming rates remain unclear. In this study, we attribute the Eurasian multidecadal temperature variations by using a combination of low-frequency component analysis and the dynamical adjustment method. We show that anthropogenic forcing has caused pronounced non-linear warming, particularly over Europe–West Asia (EWA) and Northeast Asia (NEA). In contrast, internal variability is manifested as a meridional tripole pattern tightly linked to the Atlantic Multidecadal Oscillation and the Silk Road Pattern. Furthermore, we reveal that the forced SAT changes are strongly influenced by forced thermodynamic processes, which contribute more than 62.4% (62.4% – 99.5%) to the forced long-term warming over EWA and NEA. The contributions of internal thermodynamic and dynamic processes on decadal scales are more complex, as dynamic processes contribute ∼50% to the internal multidecadal SAT variations over NEA, while thermodynamic processes account for approximately 86% of the internal SAT variations over EWA. Our study not only detects and attributes multidecadal summer SAT variations, but also provides strong evidence for the decisive role of different thermodynamic and dynamic processes in the non-uniform multidecadal warming over Eurasia.