Abstract
An extreme heat wave hit western Russia in the summer of 2010. To investigate the contribution of anthropogenic climate change to this event, 100-member ensembles of atmospheric general circulation model (AGCM) experiments, with and without possible human-induced changes in sea surface temperature (SST) and sea ice, were generated. The AGCM can reproduce monthly surface air temperature (SAT) anomalies for the past 30 years over the continental area, indicating a significant influence of the anomalous boundary conditions on the surface climate variability. While the ensemble average does not capture the extremely high SAT anomaly over western Russia observed in August 2010, the ensemble covers the anomaly with the probability of occurrence at 3.3%. Without the anthropogenic change in SST and sea ice, the ensemble fails to capture the observed SAT anomaly, reducing the probability of occurrence to 0.6%. The atmospheric response to the tropical precipitation change associated with anthropogenic SST increase leads to warming over Eurasia through northward temperature advection, consistent with the observed upward SAT trend. Drying of the land surface in spring may also have favored the summer warming over western Russia.