CONCLUSION 



A multitude of factors act in different ways on hydrospheric and atmospheric conditions. In 

 certain years and periods these factors may coincide in their direction of action and cause striking 

 deviations from the average climatic and oceanographic conditions. Certain of these factors have 

 been noted and their actions studied. Other factors have likewise been noted, but their meaning has 

 not yet been properly evaluated due to insufficiency of data and too short time range of observations. 

 Finally, as more detailed examinations are made and disseminated around the world, more and 

 more new factors appear. 



Along with the continual accumulation of factual material goes a deeper and deeper develop- 

 ment of theoretical questions which permits, on the one hand, a summing up of the results of ob- 

 servations, and on the other, verifying the hypotheses reached. The development of this process 

 will be hastened if it is realized that only constant , systematic , multifold observations of hydro- 

 spheric and atmospheric conditions, made simultaneously at many points, can give us the shortest 

 road and the cheapest road (in the final result) to the solution of the important theoretical and 

 practical questions concerning the causes of long-term and seasonal fluctuations in ice abundance in 

 the various seas and concerning forecasting of such conditions in advance. 



The importance of ice in the life of the world is sufficiently defined by the fact that about 2 per 

 cent of the water on the earth is in solid form. Ice has particular importance for life in the ocean. 



During the great periods of freezing, the accumulated ice broke through the earth's crust with 

 its weight. With the onset of the warm periods, the melting of ice occurred faster than the return 

 upheaval of the land, and the ocean flooded the hollows which were formed, thus creating the 

 epicontinental seas. 



Present day ice likewise reacts on ocean conditions in a most substantial manner. Due to ice, 

 the shoreline and relief of bottom near the shore changes . The products of destruction of the 

 shores, not only in the form of fragmented material but also in the form of great blocks of shore 

 rock, are carried by ice far out from the shores and fall to the bottom of the open sea. Ice forma- 

 tion and melting change the salinity of the ocean. Ice creates favorable biological conditions in 

 certain regions, unfavorable in others, and in certain regions the transfer from one type of condi- 

 tion to the other is seasonal ui nature. The influence of ice on climate is very great. The sea 

 covered by ice is not only protected from deep winter cooling but is also isolated from summer 

 heating. 



The great quantities of heat given off in the process of ice formation mitigate the winter air 

 temperatures, while the heat absorbed in melting lowers the summer temperatures of the corre- 

 sponding ocean regions. The constant transfer of ice from the polar areas into the lower latitudes 

 is of still greater climatic significance. The quantity of ice which forms and melts away in place, 

 and the quantity carried out of the polar regions changes from year to year to a considerable degree, 

 and significant changes in world weather are connected with this. 



The ice in the sea directly reflects on the practical activity of man, making navigation diffi- 

 cult in certain regions. Icebergs carried by the Labrador current into the Atlantic Ocean are, in 

 certain years and months, a constant threat to sea routes of communication between the main ports 

 of Europe and America. 



477 



