Arctic sea ice loss drives enhanced East Asian summer temperature variability

Abstract This study investigates the link between enhanced Arctic sea ice (ASI) variability and increased summer temperature variability over East Asia since the early 2000s. We find that the rate of ASI decline has accelerated during this period, accompanied by a near doubling of its interannual variability. This heightened variability is associated with a reorganization of Arctic atmospheric circulation, characterized by the increased prominence and intensified variability of a dipole-like mode. This mode is strongly correlated with the marked increase in summer surface temperature variability across East Asia. The underlying mechanism involves the dipole-like mode driving pronounced meridional shifts in the East Asian jet stream, which reshape the upper-tropospheric structure and generate opposing cooling and warming anomalies, thereby amplifying regional temperature contrasts. These results indicate that the loss of ASI affects not only the mean-state of Arctic circulation but also enhances its dynamical variability, strengthening Arctic–midlatitude teleconnections and increasing the likelihood of extreme climate events. Our findings highlight summer ASI variability as a critical factor influencing midlatitude climate variability and prediction uncertainty, underscoring its importance for future seasonal forecasts and long-term climate risk assessments in East Asia.