In recent decades wildfires have occurred frequently over eastern Siberia, which favors increased atmospheric carbon dioxide and air pollution. However, it is not well understood what factors have contributed to the recent increase in these wildfires. Here, we analyzed meteorological and satellite data to show that background Arctic warming related to summer Russian Arctic sea-ice decline can account for about 84% of the increase in eastern Siberian wildfires during 2004-2021 with the remaining 16% related to internal atmospheric variability associated with changes in Siberian blocking events.
We further demonstrate that Siberian blocking events occur at higher latitudes, are more persistent and have larger zonal scales over 2004-2021 than during 1979-2003 due to reduced meridional potential vorticity gradients caused by background Arctic warming during the latter period. These changes lead to more persistent, widespread and intense wildfires and their poleward migation, thus contributing to the recent increases in eastern Siberian wildfires.