Weakened Circum-global Teleconnection Pattern under global warming would exacerbate heat extremes across Eurasia

The boreal summer Circum-global teleconnection (CGT) pattern is identified as a stationary Rossby wave train propagating along the subtropical jet at interannual timescale. The variation of CGT is closely linked to the occurrence of heat extremes over mid-latitude regions. How CGT would change under global warming and the associated climatic effect remains unclear. Here, based on 34 models from Coupled Model Intercomparison Project phase 6 (CMIP6), we show evidence that the amplitude of CGT wave train will reduce robustly by 2100, with multi-model ensemble mean decrease of 31.8%. The reduction of CGT amplitude is reflected in the decrease of Rossby wave source (RWS) anomalies, with upstream signal located at jet entrance over eastern Mediterranean. The weakening of eastern Mediterranean RWS anomalies is further resulted from decreased circulation anomalies. The weakened CGT further alters the pattern of associated heat extreme events. Heat extreme days during each positive CGT event significantly increase from 5.5 days to 7.0 days at four hotspot regions across mid-latitudes: eastern Europe, Tibetan Plateau, northeastern Asia and southern Great Plains. Our findings highlight the aggravation of heat extremes induced by change of atmospheric teleconnection under global warming and additional burden on food security and ecosystems for policymakers to consider.