vertical circulation would be intensified and this would partially increase the entrance of Atlantic 

 water into the Arctic Basin. 



Considering that the layer of surface arctic water is formed partly by precipitation but chiefly 

 by coastal drainage, Nansen came to the conclusion that if the Siberian and American rivers had 

 emptied into the Pacific or Atlantic Ocean in the early geological periods, arctic surface water 

 would be warmer. But, adds Nansen, such great changes in the direction of coastal drainage could 

 barely have occurred in comparatively recent geological periods. It seems to me that Nansen 

 somewhat exaggerates the role of coastal drainage in this respect. Actually, we have seen that on 

 account of repeated melting and freezing as well as for other reasons, the arctic surface water in 

 the central part of the Arctic Basin is fresher (less saUne) than on the periphery. 



Nansen considered that possible variations in depth and outlines of shores and sea bottom in 

 the northern seas might be another cause of variation in climate. 



The underwater ridges between Greenland, Iceland and Norway, and likewise between Novaya 

 Zemlya, Franz Joseph Land, Spitzbergen and Greenland certainly retard the water exchange be- 

 tween the Atlantic Ocean and the Arctic Basin. 



In recent geological periods there were evidently fluctuations of sea level along the coasts of 

 the North Atlantic, Norwegian Sea, and the Arctic Basin, reaching amplitudes of 1000 m at the 

 very least. The lowering of the land level and the ocean bottom brought about a milder climate in 

 the arctic regions, particularly in Scandinavia and to some extent in Northern Russia and Siberia. 



On the other hand, a lowering of sea level, let us say by 500 m, would cause still greater 

 changes. The Baffin, Greenland and Norwegian Seas would be almost completely cut off from the 

 Atlantic Ocean. The warm Atlantic water would not enter these seas and the ice would not be 

 carried out of these seas into the Atlantic. Under such conditions a glacial period would begin in 

 Scandinavia and its climate would become like the present climate in southern Greenland. 



However, in Nansen's opinion, such fluctuations in sea level and other variations in the circu- 

 lation of the hydrosphere in the northern seas cannot explain the tremendous changes in climate 

 noted by geologists in Spitzbergen, the New Siberian Islands, western Greenland, etc. 



LITERATURE: 62, 77, 165. 



Section 160. Climatic Factors 



There are as yet no complete and generally accepted hypotheses to explain the short-term and 

 long-term deviations from the norm of ice abundance and their connection with variations in hydro- 

 spheric and atmospheric conditions. This is, of course, due to the unusual complexity of the 

 question. Actually, while the behavior of the trade winds in the Atlantic Ocean affects the behavior 

 of the Gulf Stream, and while the intensity of the southwestern air current affects the behavior of the 

 North Atlantic drift, the Gulf Stream and the North Atlantic drift on the other hand cause the max- 

 imum anomalies of air temperature and pressure which are to be observed on the earth's surface. 



Of greatest importance for the ice abundance of the seas in the Soviet sector of the arctic, due 

 to their eastern position relative to the northern part of the Atlantic Ocean, are the temperature 

 conditions of the Gulf Stream and its offshoots. The Atlantic water not only heats the Arctic Ocean 

 but also, by indirect influence, creates the temperature and wind conditions of the air masses. 



462 



