Weakened Circum-Global Teleconnection Pattern Under Global Warming Can Modulate Heat Extremes Across Eurasia

Abstract

The boreal summer interannual Circum-global teleconnection (CGT) manifests as a Rossby wave propagating along subtropical jet. The variation of CGT effectively influences occurrence of heatwaves over mid-latitude. However, how CGT will change under global warming and its climatic impact remains unclear. Here, we use 34 Coupled Model Intercomparison Project Phase 6 models to show that the amplitude of CGT will reduce robustly by 31.8% under global warming. The reduction of CGT amplitude is reflected in decrease of Rossby wave source (RWS) anomalies, with upstream signal located at jet entrance over eastern Mediterranean. The weakening of RWS is resulted from decreased Mediterranean circulation anomalies. The weakened CGT further alters the pattern of associated heatwave events. Regional changes of heatwave duration range from 18% (1.7 days) shorter to 44% (1.9 days) longer in different hotspots. Our findings highlight the future change of atmospheric mode of variability and the associated heatwave changes.