Fig. 4: Accelerated increasing trends in European heatwaves linked to the amplified atmospheric teleconnections (AT).

Observed zonally asymmetric trends (units: gpm decade^-1) in (a) high-pressure intensity and (b) low-pressure intensity. Number of most-connected high-pressure (red markers) and low-pressure (green markers) grid cells (units: 1) for (c) Western and (d) Eastern European heatwaves. Normalized time series of g \({{PC}}_{{west}}\) and h \({{PC}}_{{east}}\), which are the principal components associated to the leading EOF mode for V500 over the Western-Europe extended region (20°–70°N, 45°W–30°E) and Eastern-Europe extended region (20°–70°N, 20°–90°E), respectively. Regressed patterns of heatwave cumulative intensity (HWI; shadings; units: K) and atmospheric circulations at 500 hPa (vectors; units: m s^-1) onto e \({{PC}}_{{west}}\) and f \({{PC}}_{{east}}\). Significant trends (\(p < 0.1\)) and significant anomalies (\(p < 0.05\)) are hatched in (a, b) and (e, f), respectively. Only the significant atmospheric circulations (\(p < 0.05\)) are plotted in (e, f). Western Europe (WE; 35°–55°N, 10°W–25°E) and Eastern Europe (EE; 45°–65°N, 25°–55°E) are outlined by the red boxes in (a). Northeastern Atlantic (40°–60°N, 45°W–0°), northern Africa (22°–38°N, 5°–25°E), central Asia-central Russia (25°–60°N, 58°–85°E, and 60°–75°N, 58°–102°E) are outlined by the blue boxes in (b–d). The red boxes in (e, f) present the domains of Western-Europe extended region and Eastern-Europe extended region for EOF analysis.