Fig. 8: Schematic diagrams of the physical mechanisms of summer Arctic warming influencing atmospheric blocking and summer Russian Arctic sea-ice decline affecting eastern Siberian wildfires via changes in background Arctic warming, stationary anticyclonic anomaly, and Siberian blocking (SB) events.

a Schematic diagram of the influence of summer Arctic warming on atmospheric blocking via reducing meridional background potential vorticity gradient (PV_y), in which a small PV_y favors increased persistence, zonal scale, westward movement, and slow decay of atmospheric blocking and b the pathway of the influence of Russian Arctic sea-ice loss on eastern Siberian wildfires via Arctic warming is described as follows: Russian Arctic sea-ice decline (green box) can induce background Arctic warming (BAW) and stationary anticyclonic anomaly (heavy red box) over eastern Siberia, leading to a small PV_y (blue box) in the south side of eastern Siberian high latitudes, which induces longer-lasting Siberian blocking (SB) events with larger zonal scale, less eastward movement and slower decay (purple box). The joint role of the background Arctic warming- and SB-induced wildfires (orange box) leads to increased eastern Siberian wildfires in high latitudes (coral red box).