1897.] NANSEN — POLAR EXPEDITION, 1893-96. 453 



would produce a cooling down of the polar region to a much 

 greater extent than exists to-day. 



Consequently we would have in the north a colder climate, and 

 we would at the same time have a warmer climate in the south, be- 

 cause the ocean would not be cooled down by the northern ice, and 

 it would be prevented from giving off a good deal of its heat to the 

 polar region. That might to some extent explain a colder climate 

 in the north and a warmer climate in the south, but I do not think 

 it would be sufficient to explain the glacial periods. It gives us, 

 however, some idea, or some factor that would explain the changes 

 of climate on the surface of the globe. 



You might ask what would be the result if we could open out the 

 entrance to the polar sea and let more warm water flow into it. If, 

 for instance, the Bering's Strait could be made much wider and 

 deeper than at present, so that the warm Japanese current, the 

 Kurosiwo, could run into the polar sea, its temperature would then, 

 of course, be very much higher than at present. It would still be 

 covered by a layer of fresher water from the rivers flowing out of 

 Siberia and America, but the thickness of the ice would be less than 

 at present. If we, however, could let the rivers of Siberia flow in 

 some other direction, not going into the polar sea, but somewhere 

 else, so that the polar sea would not be covered by such a layer of 

 fresh and cold water, what would be the result ? The warmer water 

 would then come up to the surface, the ice would necessarily be 

 thinner, we would get much more open sea in the north, and to 

 some extent the climate would be milder. At the same time much 

 more cold water would run out of the polar sea into the Pacific and 

 Atlantic oceans, and would cool down the temperatures in those 

 latitudes. 



I do not think this explanation is sufficient to account for the 

 much warmer climate in the north when we, for example, had a sub- 

 tropical climate in Greenland and Spitzbergen. At the same time 

 it may give you some idea of what such changes in the distribution 

 of the land and water would result in. 



I will not go further into these very difficult questions. I just 

 mention this to show you what glimpses polar exploration might 

 give us into the conditions existing during other ages of the earth. 

 This is only one side of the many results which polar explorers have 

 brought back from the polar regions. They have to a great extent 

 enlarged the knowledge of humanity. They have made it possible 



PROC. AMER. PHILOS. SOC. XXXVI. 156. 2 E. PRINTED JAN. 31, 1898, 



