In the East European Plain, the Early 20th Century Warming (ETCW) was marked by an unprecedented rise and fall in the annual runoff of the Volga and Northern Dvina rivers in 1920-1940, recorded in the long-term, since 1882, hydrological time-series. Analysis of the temperature and precipitation anomalies and Palmer Drought Severity Index, basing on observational data (CRUTEM.5, GISS, CRU TS4.05, CRU-scPDSI) and 20th century reanalysis (ERA20C, CERA20C), proves the uniqueness of the period 1920-1940 associated with large-scale humidification extreme anomalies of both signs.

Patterns of surface atmospheric pressure anomalies (Had SLP.2), obtained for the years of maxima (1936 and 1938) and minima (1926-1928) of the drought conditions during the summer months (July-August) averaged for the sector 20-60N, 45-70 E, as well as the difference between them, indicate the circulation factors of the drought conditions of the 1930s and the accompanying remote anomalies of SLP. Propagation of the northern tropical belt eastward, beyond the Ural Ridge, and northward, to the Arctic coast and the Barents Sea, which corresponds to the extensive anticyclonic anomaly SLP centered over the Middle Urals results to conditions for the advection of hot and dry air mass from North Africa toward high latitudes. The anticyclonic anomaly is accompanied by a cyclonic anomaly over the circumpolar zone, spreading to the northeast of the Atlantic and able to intensify advection of tropical air masses through the East European Plain to the Arctic coast and Barents Sea.

The positive phase of the Atlantic Multi-decadal Oscillation considered as one of the main cause of the ETCW, can impact the formation of the circulation dipole mentioned above, as well as the loss of sea ice in the Barents and Kara Seas. The spatial features of the differences of sea ice concentration indicates the influence of the variability in the warm Atlantic water inflow to the Barents and Kara Seas. In turn, sea ice decline in the Barents Sea in spring can lead to a formation of cyclonic vortex over Barents Sea. This atmosphere circulation response, in term, can increase oceanic inflow of warm and salty Atlantic water masses. This positive feedback causes to further sea ice loss.