CLIMATE OF PLEISTOCENE PERIOD. 



39 



the North Atlantic could ever give rise to a Siberian climate in 

 North-western Europe. Were the Gulf Stream, which so pro- 

 foundly modifies the winter temperature of Europe, to be with- 

 drawn, the winters in our islands would become colder than 

 they are at present by more than 25 . 1 Nor would this fall of 

 temperature be counterbalanced, as it were, by a corresponding 

 increase of temperature in summer. On the contrary, we might 

 look for quite an opposite result. Superficial currents of cold 

 water coming from the Arctic regions would cool the summer 

 temperature along all the west coast of Europe, just in the same 

 way as the Labrador Current affects the summer temperature of 

 the coast lands of British America and the New England States. 

 A glance at the following Table, in which are given the mean 

 winter and summer temperatures of places in the same latitudes 

 of North America and Europe, will show what effect the Gulf 

 Stream has in modifying our European climate. Were that 

 current to disappear, our coasts might well be washed by as 

 cold water as that of the Labrador Current ; and thus not only 

 the winter, but the summer also, over all Western and North- 

 western Europe would be considerably affected. 



1 The normal temperature of the latitude of London is 40°, which is 30° 

 higher than it would be were all oceanic and aerial currents to be stopped. 

 And Dr. Croll calculates that the actual rise of temperature at London due to the 

 influence of the Gulf Stream, over and above all the lowering effects produced by 

 Arctic currents, is as much as 40°. — See Climate and Time,, p. 43. 



2 The winter temperature is that of the January isothermal line, which 

 reaches the Labrador coast in lat. 55°. The July isotherm of 50° passes through 

 lat. 53° 30', the July temperature of 49° given above being only approximate. 

 The temperature for that month at Nain on the same coast, in lat. 56° 22', is 

 48°"2 ; and the mean of January is 2° - 4. 



