Future equivalent of 2010 Russian heatwave intensified by weakening soil moisture constraints

The 2010 heatwave in eastern Europe and Russia (EHW) ranks among the hottest events ever recorded in the region. The excessive summer warmth was related to an anomalously widespread and intense quasi-stationary anticyclonic circulation anomaly over western Russia, reinforced by depletion of spring soil moisture. At present, high soil moisture levels and strong surface evaporation generally tend to cap maximum summer temperatures, but these constraints may weaken under future warming. Here, we use a data assimilation technique in which future climate model simulations are nudged to realistically represent the persistence and strength of the 2010 blocked atmospheric flow. In the future, synoptically-driven extreme warming under favourable large-scale atmospheric conditions will no longer be suppressed by abundant soil moisture, leading to a disproportional intensification of future heat waves. This implies that future mid-latitude heat waves analogous to the2010 event will become even more extreme than previously thought, with temperature extremes increasing by 8.4C over Western Russia. Thus, the socioeconomic impacts of future heatwaves may likely be amplified beyond current estimates.