Аннотация:This study presents a spatio-temporal analysis of changes in long-term river runoff and the frequency of years with extremely low flows in European Russia (ER) in the 21st century. The analysis is based on climate projections from an ensemble of the 12 models of the global coupled ocean-atmosphere general circulation models (GCMs) of Phase 5 of the Coupled Model Intercomparison Project (CMIP5) that most reliably reflect the regional climate. We found that the mean long-term river runoff is not credibly reproduced by the ensemble of models. To evaluate the characteristics of annual runoff and its variability index, we propose several methods based on water-balance relations. According to RCP (representative concentration pathway) 4.5 and RCP 8.5 scenarios, these methods predict multidirectional changes in the frequency of extremely dry years in European Russia. While an insignificant decrease in the probability of extremely dry years is predicted in the centre of the study area throughout the 21st century, a significant increase — by a factor of 2 to 4 times — is predicted for southern European Russia. The most unfavourable projections of the future regional climate suggest a possible increase in the probability of low-water years of 6–8 times and catastrophic reduction of the annual river runoff of less than half the modern flow.
