A teleconnection pathway linking cross-basin extremes triggered the record-breaking 2024 marine heatwave in the East China Seas

Abstract In 2024, a record-breaking marine heatwave (MHW) occurred in the East China Seas (ECSs), lasting four months and featuring consecutive 21 d periods exceeding the extreme heatwave threshold. Based on a mixed–layer heat budget analysis, this study identifies the dominant contribution of increased shortwave radiation, which is closely linked to atmospheric high–pressure anomalies. These high-pressure anomalies were established via a teleconnection pathway triggered by a series of cross-basin extremes. Specifically, extreme warming in the North Atlantic (NA), together with slightly cooler conditions in the eastern equatorial Pacific, produced a pronounced cross-basin sea surface temperature contrast. This contrast subsequently contributed to unprecedented precipitation over North Africa. These remote extremes further excited a strong wave train, ultimately leading to the record-breaking MHW. Under the background of sustained NA warming, this teleconnection pathway becomes more pronounced and continues to facilitate MHW development. This study advances our understanding of the mechanisms by which remote signals trigger MHWs and highlights the potential for increased MHW risk in a warming climate.