452 NANSEN — POLAR EXPEDITION, 1893-96. [Oct. 29, 



It may seem rather striking that the sea should be so warm in the 

 depths and so cold on the surface. The reason is natural. I may 

 say first that the cold surface layer of water was fresher than the 

 lower warm layers. The deeper water had a high salinity very 

 much like the Atlantic water. That is the reason why this warm 

 water is heavier than the cold water and keeps below. All this 

 salt and comparatively warm water runs into the polar sea from the 

 Atlantic ocean, filling the whole depth of the polar basin, while its 

 surface water to some extent is mixed up with the fresh water run- 

 ning in from the American and Siberian rivers. 



The Atlantic water is slowly cooled down and is gradually, to 

 some extent, mixed with the fresher water of the surface and is then 

 again carried out into the Atlantic ocean as water with less salinity 

 than the Atlantic water and much colder; and on that account is 

 heavier and sinks and fills the bottom of the sea. What is the 

 result of these conditions? The result is that the fresh water 

 floating on the top of the salt warm water protects the ice to some 

 extent from the influence of the heat which is carried into the polar 

 sea by the Atlantic water. It allows that ice to grow slowly year 

 after year. If this fresh water had not existed the Atlantic water 

 would come to the surface in the polar sea, and this covering of ice 

 would consequently be very much thinner. 



If we look backward through the ages and ask what the result 

 would have been if the geographical distribution of the land and 

 water were a little different from what it is to-day, what result would 

 we expect? What would the result be if we were to shut up the 

 whole polar basin, not allowing this warm water to flow into it and 

 not allowing the ice and the cold water to float out of this polar sea? 

 If we had a bridge of land passing from Greenland to Iceland and 

 across to the Faroe and Shetland Islands, uniting Scotland and 

 England with Greenland, and consequently closing up the whole 

 entrance to the polar sea, what would be the result ? 



The result would be that no warm water would be carried from 

 the south to the polar region ; the ice would be allowed to block 

 up there year after year and would not be allowed to drift across 

 and out, and by and by the whole polar sea would necessarily be 

 covered with a very much thicker layer of ice and snow than at 

 present. This layer would at last have no more motion and the 

 thickness of the ice would allow the temperature to fall during the 

 winter on account of the radiation of heat from the surface. This 



