NOAA/WDS Paleoclimatology - Tree-ring Reconstruction of Trans-Eurasian Heatwave and Drought (TEHD) 1741-2022 CE and Circum-Global Teleconnection (CGT) 1708-2022 CE

Since the late 20th century, an emerging atmospheric teleconnection pattern, the trans-Eurasian heatwave-drought train, has intensified remarkably during summer, correlating with a surge in concurrent heatwave-drought events from Eastern Europe to East Asia. Tree-ring proxies, spanning three centuries, reveal that the recent intensity of this pattern is unprecedented in the historical records. In contrast, the circumglobal teleconnection, which historically dominated the continental-scale Eurasian heatwave occurrences, has shown no discernible trend amid global warming. Consequently, this emerging pattern signifies a radical shift in Eurasian heatwave-drought climatologies. The mechanism involves Rossby wave propagation linked to warming sea surface temperatures in the Northwestern Atlantic and enhanced Sahel precipitation, both amplified recently by overlapping effects of anthropogenic warming and natural variability. Land-atmosphere interactions driven by soil moisture deficits further intensified the pattern regionally. Climate models predict that anthropogenic forcings will continue to strengthen the pattern throughout this century.